Merge pull request #2286 from github/proxy-from-env

Support HTTPS_PROXY, NO_PROXY from environment

features/steps.rb

@@ -157,12 +157,6 @@ Given(/^the GitHub API server:$/) do |endpoints_str|
   set_environment_variable 'HUB_TEST_HOST', "http://127.0.0.1:#{@server.port}"
 end
 
-Given(/^I use a debugging proxy(?: at "(.+?)")?$/) do |address|
-  address ||= 'localhost:8888'
-  set_environment_variable 'HTTP_PROXY', address
-  set_environment_variable 'HTTPS_PROXY', address
-end
-
 Then(/^shell$/) do
   cd('.') do
     system '/bin/bash -i'

github/http.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/github/hub/ui"
 	"github.com/github/hub/utils"
+	"golang.org/x/net/http/httpproxy"
 )
 
 const apiPayloadVersion = "application/vnd.github.v3+json;charset=utf-8"
@@ -197,28 +198,13 @@ func cloneRequest(req *http.Request) *http.Request {
 	return dup
 }
 
-// An implementation of http.ProxyFromEnvironment that isn't broken
-func proxyFromEnvironment(req *http.Request) (*url.URL, error) {
-	proxy := os.Getenv("http_proxy")
-	if proxy == "" {
-		proxy = os.Getenv("HTTP_PROXY")
-	}
-	if proxy == "" {
-		return nil, nil
-	}
+var proxyFunc func(*url.URL) (*url.URL, error)
 
-	proxyURL, err := url.Parse(proxy)
-	if err != nil || !strings.HasPrefix(proxyURL.Scheme, "http") {
-		if proxyURL, err := url.Parse("http://" + proxy); err == nil {
-			return proxyURL, nil
-		}
-	}
-
-	if err != nil {
-		return nil, fmt.Errorf("invalid proxy address %q: %v", proxy, err)
+func proxyFromEnvironment(req *http.Request) (*url.URL, error) {
+	if proxyFunc == nil {
+		proxyFunc = httpproxy.FromEnvironment().ProxyFunc()
 	}
-
-	return proxyURL, nil
+	return proxyFunc(req.URL)
 }
 
 type simpleClient struct {

go.mod

@@ -14,7 +14,8 @@ require (
 	github.com/mitchellh/go-homedir v0.0.0-20161203194507-b8bc1bf76747
 	github.com/russross/blackfriday v0.0.0-20180526075726-670777b536d3
 	github.com/shurcooL/sanitized_anchor_name v0.0.0-20170918181015-86672fcb3f95 // indirect
-	golang.org/x/crypto v0.0.0-20180127211104-1875d0a70c90
+	golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2
+	golang.org/x/net v0.0.0-20191002035440-2ec189313ef0
 	golang.org/x/sys v0.0.0-20190531175056-4c3a928424d2 // indirect
 	gopkg.in/yaml.v2 v2.0.0-20190319135612-7b8349ac747c
 )

go.sum

@@ -22,8 +22,15 @@ github.com/shurcooL/sanitized_anchor_name v0.0.0-20170918181015-86672fcb3f95 h1:
 github.com/shurcooL/sanitized_anchor_name v0.0.0-20170918181015-86672fcb3f95/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
 golang.org/x/crypto v0.0.0-20180127211104-1875d0a70c90 h1:DNyuYmiOz3AH2rGH1n4YsZUvxVhkeMvSs8s31jiWpm0=
 golang.org/x/crypto v0.0.0-20180127211104-1875d0a70c90/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20191002035440-2ec189313ef0 h1:2mqDk8w/o6UmeUCu5Qiq2y7iMf6anbx+YA8d1JFoFrs=
+golang.org/x/net v0.0.0-20191002035440-2ec189313ef0/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190531175056-4c3a928424d2 h1:T5DasATyLQfmbTpfEXx/IOL9vfjzW6up+ZDkmHvIf2s=
 golang.org/x/sys v0.0.0-20190531175056-4c3a928424d2/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.0.0-20190319135612-7b8349ac747c h1:nsJYChHWxeFA6+48RmvBXEvQNanNyh933kZYWiu2HBE=

vendor/golang.org/x/crypto/ssh/terminal/terminal.go

@@ -159,6 +159,10 @@ func bytesToKey(b []byte, pasteActive bool) (rune, []byte) {
 			return keyClearScreen, b[1:]
 		case 23: // ^W
 			return keyDeleteWord, b[1:]
+		case 14: // ^N
+			return keyDown, b[1:]
+		case 16: // ^P
+			return keyUp, b[1:]
 		}
 	}
 

vendor/golang.org/x/crypto/ssh/terminal/util.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux,!appengine netbsd openbsd
+// +build aix darwin dragonfly freebsd linux,!appengine netbsd openbsd
 
 // Package terminal provides support functions for dealing with terminals, as
 // commonly found on UNIX systems.
@@ -25,7 +25,7 @@ type State struct {
 	termios unix.Termios
 }
 
-// IsTerminal returns true if the given file descriptor is a terminal.
+// IsTerminal returns whether the given file descriptor is a terminal.
 func IsTerminal(fd int) bool {
 	_, err := unix.IoctlGetTermios(fd, ioctlReadTermios)
 	return err == nil
@@ -108,9 +108,7 @@ func ReadPassword(fd int) ([]byte, error) {
 		return nil, err
 	}
 
-	defer func() {
-		unix.IoctlSetTermios(fd, ioctlWriteTermios, termios)
-	}()
+	defer unix.IoctlSetTermios(fd, ioctlWriteTermios, termios)
 
 	return readPasswordLine(passwordReader(fd))
 }

vendor/golang.org/x/crypto/ssh/terminal/util_aix.go

+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build aix
+
+package terminal
+
+import "golang.org/x/sys/unix"
+
+const ioctlReadTermios = unix.TCGETS
+const ioctlWriteTermios = unix.TCSETS

vendor/golang.org/x/crypto/ssh/terminal/util_plan9.go

@@ -21,7 +21,7 @@ import (
 
 type State struct{}
 
-// IsTerminal returns true if the given file descriptor is a terminal.
+// IsTerminal returns whether the given file descriptor is a terminal.
 func IsTerminal(fd int) bool {
 	return false
 }

vendor/golang.org/x/crypto/ssh/terminal/util_solaris.go

@@ -14,10 +14,10 @@ import (
 
 // State contains the state of a terminal.
 type State struct {
-	state *unix.Termios
+	termios unix.Termios
 }
 
-// IsTerminal returns true if the given file descriptor is a terminal.
+// IsTerminal returns whether the given file descriptor is a terminal.
 func IsTerminal(fd int) bool {
 	_, err := unix.IoctlGetTermio(fd, unix.TCGETA)
 	return err == nil
@@ -75,47 +75,43 @@ func ReadPassword(fd int) ([]byte, error) {
 // restored.
 // see http://cr.illumos.org/~webrev/andy_js/1060/
 func MakeRaw(fd int) (*State, error) {
-	oldTermiosPtr, err := unix.IoctlGetTermios(fd, unix.TCGETS)
+	termios, err := unix.IoctlGetTermios(fd, unix.TCGETS)
 	if err != nil {
 		return nil, err
 	}
-	oldTermios := *oldTermiosPtr
-
-	newTermios := oldTermios
-	newTermios.Iflag &^= syscall.IGNBRK | syscall.BRKINT | syscall.PARMRK | syscall.ISTRIP | syscall.INLCR | syscall.IGNCR | syscall.ICRNL | syscall.IXON
-	newTermios.Oflag &^= syscall.OPOST
-	newTermios.Lflag &^= syscall.ECHO | syscall.ECHONL | syscall.ICANON | syscall.ISIG | syscall.IEXTEN
-	newTermios.Cflag &^= syscall.CSIZE | syscall.PARENB
-	newTermios.Cflag |= syscall.CS8
-	newTermios.Cc[unix.VMIN] = 1
-	newTermios.Cc[unix.VTIME] = 0
-
-	if err := unix.IoctlSetTermios(fd, unix.TCSETS, &newTermios); err != nil {
+
+	oldState := State{termios: *termios}
+
+	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
+	termios.Oflag &^= unix.OPOST
+	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
+	termios.Cflag &^= unix.CSIZE | unix.PARENB
+	termios.Cflag |= unix.CS8
+	termios.Cc[unix.VMIN] = 1
+	termios.Cc[unix.VTIME] = 0
+
+	if err := unix.IoctlSetTermios(fd, unix.TCSETS, termios); err != nil {
 		return nil, err
 	}
 
-	return &State{
-		state: oldTermiosPtr,
-	}, nil
+	return &oldState, nil
 }
 
 // Restore restores the terminal connected to the given file descriptor to a
 // previous state.
 func Restore(fd int, oldState *State) error {
-	return unix.IoctlSetTermios(fd, unix.TCSETS, oldState.state)
+	return unix.IoctlSetTermios(fd, unix.TCSETS, &oldState.termios)
 }
 
 // GetState returns the current state of a terminal which may be useful to
 // restore the terminal after a signal.
 func GetState(fd int) (*State, error) {
-	oldTermiosPtr, err := unix.IoctlGetTermios(fd, unix.TCGETS)
+	termios, err := unix.IoctlGetTermios(fd, unix.TCGETS)
 	if err != nil {
 		return nil, err
 	}
 
-	return &State{
-		state: oldTermiosPtr,
-	}, nil
+	return &State{termios: *termios}, nil
 }
 
 // GetSize returns the dimensions of the given terminal.

vendor/golang.org/x/crypto/ssh/terminal/util_windows.go

@@ -26,7 +26,7 @@ type State struct {
 	mode uint32
 }
 
-// IsTerminal returns true if the given file descriptor is a terminal.
+// IsTerminal returns whether the given file descriptor is a terminal.
 func IsTerminal(fd int) bool {
 	var st uint32
 	err := windows.GetConsoleMode(windows.Handle(fd), &st)
@@ -64,13 +64,15 @@ func Restore(fd int, state *State) error {
 	return windows.SetConsoleMode(windows.Handle(fd), state.mode)
 }
 
-// GetSize returns the dimensions of the given terminal.
+// GetSize returns the visible dimensions of the given terminal.
+//
+// These dimensions don't include any scrollback buffer height.
 func GetSize(fd int) (width, height int, err error) {
 	var info windows.ConsoleScreenBufferInfo
 	if err := windows.GetConsoleScreenBufferInfo(windows.Handle(fd), &info); err != nil {
 		return 0, 0, err
 	}
-	return int(info.Size.X), int(info.Size.Y), nil
+	return int(info.Window.Right - info.Window.Left + 1), int(info.Window.Bottom - info.Window.Top + 1), nil
 }
 
 // ReadPassword reads a line of input from a terminal without local echo.  This
@@ -89,9 +91,7 @@ func ReadPassword(fd int) ([]byte, error) {
 		return nil, err
 	}
 
-	defer func() {
-		windows.SetConsoleMode(windows.Handle(fd), old)
-	}()
+	defer windows.SetConsoleMode(windows.Handle(fd), old)
 
 	var h windows.Handle
 	p, _ := windows.GetCurrentProcess()

vendor/golang.org/x/net/AUTHORS

+# This source code refers to The Go Authors for copyright purposes.
+# The master list of authors is in the main Go distribution,
+# visible at http://tip.golang.org/AUTHORS.

vendor/golang.org/x/net/CONTRIBUTORS

+# This source code was written by the Go contributors.
+# The master list of contributors is in the main Go distribution,
+# visible at http://tip.golang.org/CONTRIBUTORS.

vendor/golang.org/x/net/LICENSE

+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/golang.org/x/net/PATENTS

+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

vendor/golang.org/x/net/http/httpproxy/proxy.go

+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package httpproxy provides support for HTTP proxy determination
+// based on environment variables, as provided by net/http's
+// ProxyFromEnvironment function.
+//
+// The API is not subject to the Go 1 compatibility promise and may change at
+// any time.
+package httpproxy
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"net/url"
+	"os"
+	"strings"
+	"unicode/utf8"
+
+	"golang.org/x/net/idna"
+)
+
+// Config holds configuration for HTTP proxy settings. See
+// FromEnvironment for details.
+type Config struct {
+	// HTTPProxy represents the value of the HTTP_PROXY or
+	// http_proxy environment variable. It will be used as the proxy
+	// URL for HTTP requests and HTTPS requests unless overridden by
+	// HTTPSProxy or NoProxy.
+	HTTPProxy string
+
+	// HTTPSProxy represents the HTTPS_PROXY or https_proxy
+	// environment variable. It will be used as the proxy URL for
+	// HTTPS requests unless overridden by NoProxy.
+	HTTPSProxy string
+
+	// NoProxy represents the NO_PROXY or no_proxy environment
+	// variable. It specifies a string that contains comma-separated values
+	// specifying hosts that should be excluded from proxying. Each value is
+	// represented by an IP address prefix (1.2.3.4), an IP address prefix in
+	// CIDR notation (1.2.3.4/8), a domain name, or a special DNS label (*).
+	// An IP address prefix and domain name can also include a literal port
+	// number (1.2.3.4:80).
+	// A domain name matches that name and all subdomains. A domain name with
+	// a leading "." matches subdomains only. For example "foo.com" matches
+	// "foo.com" and "bar.foo.com"; ".y.com" matches "x.y.com" but not "y.com".
+	// A single asterisk (*) indicates that no proxying should be done.
+	// A best effort is made to parse the string and errors are
+	// ignored.
+	NoProxy string
+
+	// CGI holds whether the current process is running
+	// as a CGI handler (FromEnvironment infers this from the
+	// presence of a REQUEST_METHOD environment variable).
+	// When this is set, ProxyForURL will return an error
+	// when HTTPProxy applies, because a client could be
+	// setting HTTP_PROXY maliciously. See https://golang.org/s/cgihttpproxy.
+	CGI bool
+}
+
+// config holds the parsed configuration for HTTP proxy settings.
+type config struct {
+	// Config represents the original configuration as defined above.
+	Config
+
+	// httpsProxy is the parsed URL of the HTTPSProxy if defined.
+	httpsProxy *url.URL
+
+	// httpProxy is the parsed URL of the HTTPProxy if defined.
+	httpProxy *url.URL
+
+	// ipMatchers represent all values in the NoProxy that are IP address
+	// prefixes or an IP address in CIDR notation.
+	ipMatchers []matcher
+
+	// domainMatchers represent all values in the NoProxy that are a domain
+	// name or hostname & domain name
+	domainMatchers []matcher
+}
+
+// FromEnvironment returns a Config instance populated from the
+// environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the
+// lowercase versions thereof). HTTPS_PROXY takes precedence over
+// HTTP_PROXY for https requests.
+//
+// The environment values may be either a complete URL or a
+// "host[:port]", in which case the "http" scheme is assumed. An error
+// is returned if the value is a different form.
+func FromEnvironment() *Config {
+	return &Config{
+		HTTPProxy:  getEnvAny("HTTP_PROXY", "http_proxy"),
+		HTTPSProxy: getEnvAny("HTTPS_PROXY", "https_proxy"),
+		NoProxy:    getEnvAny("NO_PROXY", "no_proxy"),
+		CGI:        os.Getenv("REQUEST_METHOD") != "",
+	}
+}
+
+func getEnvAny(names ...string) string {
+	for _, n := range names {
+		if val := os.Getenv(n); val != "" {
+			return val
+		}
+	}
+	return ""
+}
+
+// ProxyFunc returns a function that determines the proxy URL to use for
+// a given request URL. Changing the contents of cfg will not affect
+// proxy functions created earlier.
+//
+// A nil URL and nil error are returned if no proxy is defined in the
+// environment, or a proxy should not be used for the given request, as
+// defined by NO_PROXY.
+//
+// As a special case, if req.URL.Host is "localhost" (with or without a
+// port number), then a nil URL and nil error will be returned.
+func (cfg *Config) ProxyFunc() func(reqURL *url.URL) (*url.URL, error) {
+	// Preprocess the Config settings for more efficient evaluation.
+	cfg1 := &config{
+		Config: *cfg,
+	}
+	cfg1.init()
+	return cfg1.proxyForURL
+}
+
+func (cfg *config) proxyForURL(reqURL *url.URL) (*url.URL, error) {
+	var proxy *url.URL
+	if reqURL.Scheme == "https" {
+		proxy = cfg.httpsProxy
+	}
+	if proxy == nil {
+		proxy = cfg.httpProxy
+		if proxy != nil && cfg.CGI {
+			return nil, errors.New("refusing to use HTTP_PROXY value in CGI environment; see golang.org/s/cgihttpproxy")
+		}
+	}
+	if proxy == nil {
+		return nil, nil
+	}
+	if !cfg.useProxy(canonicalAddr(reqURL)) {
+		return nil, nil
+	}
+
+	return proxy, nil
+}
+
+func parseProxy(proxy string) (*url.URL, error) {
+	if proxy == "" {
+		return nil, nil
+	}
+
+	proxyURL, err := url.Parse(proxy)
+	if err != nil ||
+		(proxyURL.Scheme != "http" &&
+			proxyURL.Scheme != "https" &&
+			proxyURL.Scheme != "socks5") {
+		// proxy was bogus. Try prepending "http://" to it and
+		// see if that parses correctly. If not, we fall
+		// through and complain about the original one.
+		if proxyURL, err := url.Parse("http://" + proxy); err == nil {
+			return proxyURL, nil
+		}
+	}
+	if err != nil {
+		return nil, fmt.Errorf("invalid proxy address %q: %v", proxy, err)
+	}
+	return proxyURL, nil
+}
+
+// useProxy reports whether requests to addr should use a proxy,
+// according to the NO_PROXY or no_proxy environment variable.
+// addr is always a canonicalAddr with a host and port.
+func (cfg *config) useProxy(addr string) bool {
+	if len(addr) == 0 {
+		return true
+	}
+	host, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		return false
+	}
+	if host == "localhost" {
+		return false
+	}
+	ip := net.ParseIP(host)
+	if ip != nil {
+		if ip.IsLoopback() {
+			return false
+		}
+	}
+
+	addr = strings.ToLower(strings.TrimSpace(host))
+
+	if ip != nil {
+		for _, m := range cfg.ipMatchers {
+			if m.match(addr, port, ip) {
+				return false
+			}
+		}
+	}
+	for _, m := range cfg.domainMatchers {
+		if m.match(addr, port, ip) {
+			return false
+		}
+	}
+	return true
+}
+
+func (c *config) init() {
+	if parsed, err := parseProxy(c.HTTPProxy); err == nil {
+		c.httpProxy = parsed
+	}
+	if parsed, err := parseProxy(c.HTTPSProxy); err == nil {
+		c.httpsProxy = parsed
+	}
+
+	for _, p := range strings.Split(c.NoProxy, ",") {
+		p = strings.ToLower(strings.TrimSpace(p))
+		if len(p) == 0 {
+			continue
+		}
+
+		if p == "*" {
+			c.ipMatchers = []matcher{allMatch{}}
+			c.domainMatchers = []matcher{allMatch{}}
+			return
+		}
+
+		// IPv4/CIDR, IPv6/CIDR
+		if _, pnet, err := net.ParseCIDR(p); err == nil {
+			c.ipMatchers = append(c.ipMatchers, cidrMatch{cidr: pnet})
+			continue
+		}
+
+		// IPv4:port, [IPv6]:port
+		phost, pport, err := net.SplitHostPort(p)
+		if err == nil {
+			if len(phost) == 0 {
+				// There is no host part, likely the entry is malformed; ignore.
+				continue
+			}
+			if phost[0] == '[' && phost[len(phost)-1] == ']' {
+				phost = phost[1 : len(phost)-1]
+			}
+		} else {
+			phost = p
+		}
+		// IPv4, IPv6
+		if pip := net.ParseIP(phost); pip != nil {
+			c.ipMatchers = append(c.ipMatchers, ipMatch{ip: pip, port: pport})
+			continue
+		}
+
+		if len(phost) == 0 {
+			// There is no host part, likely the entry is malformed; ignore.
+			continue
+		}
+
+		// domain.com or domain.com:80
+		// foo.com matches bar.foo.com
+		// .domain.com or .domain.com:port
+		// *.domain.com or *.domain.com:port
+		if strings.HasPrefix(phost, "*.") {
+			phost = phost[1:]
+		}
+		matchHost := false
+		if phost[0] != '.' {
+			matchHost = true
+			phost = "." + phost
+		}
+		c.domainMatchers = append(c.domainMatchers, domainMatch{host: phost, port: pport, matchHost: matchHost})
+	}
+}
+
+var portMap = map[string]string{
+	"http":   "80",
+	"https":  "443",
+	"socks5": "1080",
+}
+
+// canonicalAddr returns url.Host but always with a ":port" suffix
+func canonicalAddr(url *url.URL) string {
+	addr := url.Hostname()
+	if v, err := idnaASCII(addr); err == nil {
+		addr = v
+	}
+	port := url.Port()
+	if port == "" {
+		port = portMap[url.Scheme]
+	}
+	return net.JoinHostPort(addr, port)
+}
+
+// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
+// return true if the string includes a port.
+func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
+
+func idnaASCII(v string) (string, error) {
+	// TODO: Consider removing this check after verifying performance is okay.
+	// Right now punycode verification, length checks, context checks, and the
+	// permissible character tests are all omitted. It also prevents the ToASCII
+	// call from salvaging an invalid IDN, when possible. As a result it may be
+	// possible to have two IDNs that appear identical to the user where the
+	// ASCII-only version causes an error downstream whereas the non-ASCII
+	// version does not.
+	// Note that for correct ASCII IDNs ToASCII will only do considerably more
+	// work, but it will not cause an allocation.
+	if isASCII(v) {
+		return v, nil
+	}
+	return idna.Lookup.ToASCII(v)
+}
+
+func isASCII(s string) bool {
+	for i := 0; i < len(s); i++ {
+		if s[i] >= utf8.RuneSelf {
+			return false
+		}
+	}
+	return true
+}
+
+// matcher represents the matching rule for a given value in the NO_PROXY list
+type matcher interface {
+	// match returns true if the host and optional port or ip and optional port
+	// are allowed
+	match(host, port string, ip net.IP) bool
+}
+
+// allMatch matches on all possible inputs
+type allMatch struct{}
+
+func (a allMatch) match(host, port string, ip net.IP) bool {
+	return true
+}
+
+type cidrMatch struct {
+	cidr *net.IPNet
+}
+
+func (m cidrMatch) match(host, port string, ip net.IP) bool {
+	return m.cidr.Contains(ip)
+}
+
+type ipMatch struct {
+	ip   net.IP
+	port string
+}
+
+func (m ipMatch) match(host, port string, ip net.IP) bool {
+	if m.ip.Equal(ip) {
+		return m.port == "" || m.port == port
+	}
+	return false
+}
+
+type domainMatch struct {
+	host string
+	port string
+
+	matchHost bool
+}
+
+func (m domainMatch) match(host, port string, ip net.IP) bool {
+	if strings.HasSuffix(host, m.host) || (m.matchHost && host == m.host[1:]) {
+		return m.port == "" || m.port == port
+	}
+	return false
+}

vendor/golang.org/x/net/idna/idna9.0.0.go

+// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
+
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !go1.10
+
+// Package idna implements IDNA2008 using the compatibility processing
+// defined by UTS (Unicode Technical Standard) #46, which defines a standard to
+// deal with the transition from IDNA2003.
+//
+// IDNA2008 (Internationalized Domain Names for Applications), is defined in RFC
+// 5890, RFC 5891, RFC 5892, RFC 5893 and RFC 5894.
+// UTS #46 is defined in https://www.unicode.org/reports/tr46.
+// See https://unicode.org/cldr/utility/idna.jsp for a visualization of the
+// differences between these two standards.
+package idna // import "golang.org/x/net/idna"
+
+import (
+	"fmt"
+	"strings"
+	"unicode/utf8"
+
+	"golang.org/x/text/secure/bidirule"
+	"golang.org/x/text/unicode/norm"
+)
+
+// NOTE: Unlike common practice in Go APIs, the functions will return a
+// sanitized domain name in case of errors. Browsers sometimes use a partially
+// evaluated string as lookup.
+// TODO: the current error handling is, in my opinion, the least opinionated.
+// Other strategies are also viable, though:
+// Option 1) Return an empty string in case of error, but allow the user to
+//    specify explicitly which errors to ignore.
+// Option 2) Return the partially evaluated string if it is itself a valid
+//    string, otherwise return the empty string in case of error.
+// Option 3) Option 1 and 2.
+// Option 4) Always return an empty string for now and implement Option 1 as
+//    needed, and document that the return string may not be empty in case of
+//    error in the future.
+// I think Option 1 is best, but it is quite opinionated.
+
+// ToASCII is a wrapper for Punycode.ToASCII.
+func ToASCII(s string) (string, error) {
+	return Punycode.process(s, true)
+}
+
+// ToUnicode is a wrapper for Punycode.ToUnicode.
+func ToUnicode(s string) (string, error) {
+	return Punycode.process(s, false)
+}
+
+// An Option configures a Profile at creation time.
+type Option func(*options)
+
+// Transitional sets a Profile to use the Transitional mapping as defined in UTS
+// #46. This will cause, for example, "ß" to be mapped to "ss". Using the
+// transitional mapping provides a compromise between IDNA2003 and IDNA2008
+// compatibility. It is used by most browsers when resolving domain names. This
+// option is only meaningful if combined with MapForLookup.
+func Transitional(transitional bool) Option {
+	return func(o *options) { o.transitional = true }
+}
+
+// VerifyDNSLength sets whether a Profile should fail if any of the IDN parts
+// are longer than allowed by the RFC.
+func VerifyDNSLength(verify bool) Option {
+	return func(o *options) { o.verifyDNSLength = verify }
+}
+
+// RemoveLeadingDots removes leading label separators. Leading runes that map to
+// dots, such as U+3002 IDEOGRAPHIC FULL STOP, are removed as well.
+//
+// This is the behavior suggested by the UTS #46 and is adopted by some
+// browsers.
+func RemoveLeadingDots(remove bool) Option {
+	return func(o *options) { o.removeLeadingDots = remove }
+}
+
+// ValidateLabels sets whether to check the mandatory label validation criteria
+// as defined in Section 5.4 of RFC 5891. This includes testing for correct use
+// of hyphens ('-'), normalization, validity of runes, and the context rules.
+func ValidateLabels(enable bool) Option {
+	return func(o *options) {
+		// Don't override existing mappings, but set one that at least checks
+		// normalization if it is not set.
+		if o.mapping == nil && enable {
+			o.mapping = normalize
+		}
+		o.trie = trie
+		o.validateLabels = enable
+		o.fromPuny = validateFromPunycode
+	}
+}
+
+// StrictDomainName limits the set of permissable ASCII characters to those
+// allowed in domain names as defined in RFC 1034 (A-Z, a-z, 0-9 and the
+// hyphen). This is set by default for MapForLookup and ValidateForRegistration.
+//
+// This option is useful, for instance, for browsers that allow characters
+// outside this range, for example a '_' (U+005F LOW LINE). See
+// http://www.rfc-editor.org/std/std3.txt for more details This option
+// corresponds to the UseSTD3ASCIIRules option in UTS #46.
+func StrictDomainName(use bool) Option {
+	return func(o *options) {
+		o.trie = trie
+		o.useSTD3Rules = use
+		o.fromPuny = validateFromPunycode
+	}
+}
+
+// NOTE: the following options pull in tables. The tables should not be linked
+// in as long as the options are not used.
+
+// BidiRule enables the Bidi rule as defined in RFC 5893. Any application
+// that relies on proper validation of labels should include this rule.
+func BidiRule() Option {
+	return func(o *options) { o.bidirule = bidirule.ValidString }
+}
+
+// ValidateForRegistration sets validation options to verify that a given IDN is
+// properly formatted for registration as defined by Section 4 of RFC 5891.
+func ValidateForRegistration() Option {
+	return func(o *options) {
+		o.mapping = validateRegistration
+		StrictDomainName(true)(o)
+		ValidateLabels(true)(o)
+		VerifyDNSLength(true)(o)
+		BidiRule()(o)
+	}
+}
+
+// MapForLookup sets validation and mapping options such that a given IDN is
+// transformed for domain name lookup according to the requirements set out in
+// Section 5 of RFC 5891. The mappings follow the recommendations of RFC 5894,
+// RFC 5895 and UTS 46. It does not add the Bidi Rule. Use the BidiRule option
+// to add this check.
+//
+// The mappings include normalization and mapping case, width and other
+// compatibility mappings.
+func MapForLookup() Option {
+	return func(o *options) {
+		o.mapping = validateAndMap
+		StrictDomainName(true)(o)
+		ValidateLabels(true)(o)
+		RemoveLeadingDots(true)(o)
+	}
+}
+
+type options struct {
+	transitional      bool
+	useSTD3Rules      bool
+	validateLabels    bool
+	verifyDNSLength   bool
+	removeLeadingDots bool
+
+	trie *idnaTrie
+
+	// fromPuny calls validation rules when converting A-labels to U-labels.
+	fromPuny func(p *Profile, s string) error
+
+	// mapping implements a validation and mapping step as defined in RFC 5895
+	// or UTS 46, tailored to, for example, domain registration or lookup.
+	mapping func(p *Profile, s string) (string, error)
+
+	// bidirule, if specified, checks whether s conforms to the Bidi Rule
+	// defined in RFC 5893.
+	bidirule func(s string) bool
+}
+
+// A Profile defines the configuration of a IDNA mapper.
+type Profile struct {
+	options
+}
+
+func apply(o *options, opts []Option) {
+	for _, f := range opts {
+		f(o)
+	}
+}
+
+// New creates a new Profile.
+//
+// With no options, the returned Profile is the most permissive and equals the
+// Punycode Profile. Options can be passed to further restrict the Profile. The
+// MapForLookup and ValidateForRegistration options set a collection of options,
+// for lookup and registration purposes respectively, which can be tailored by
+// adding more fine-grained options, where later options override earlier
+// options.
+func New(o ...Option) *Profile {
+	p := &Profile{}
+	apply(&p.options, o)
+	return p
+}
+
+// ToASCII converts a domain or domain label to its ASCII form. For example,
+// ToASCII("bücher.example.com") is "xn--bcher-kva.example.com", and
+// ToASCII("golang") is "golang". If an error is encountered it will return
+// an error and a (partially) processed result.
+func (p *Profile) ToASCII(s string) (string, error) {
+	return p.process(s, true)
+}
+
+// ToUnicode converts a domain or domain label to its Unicode form. For example,
+// ToUnicode("xn--bcher-kva.example.com") is "bücher.example.com", and
+// ToUnicode("golang") is "golang". If an error is encountered it will return
+// an error and a (partially) processed result.
+func (p *Profile) ToUnicode(s string) (string, error) {
+	pp := *p
+	pp.transitional = false
+	return pp.process(s, false)
+}
+
+// String reports a string with a description of the profile for debugging
+// purposes. The string format may change with different versions.
+func (p *Profile) String() string {
+	s := ""
+	if p.transitional {
+		s = "Transitional"
+	} else {
+		s = "NonTransitional"
+	}
+	if p.useSTD3Rules {
+		s += ":UseSTD3Rules"
+	}
+	if p.validateLabels {
+		s += ":ValidateLabels"
+	}
+	if p.verifyDNSLength {
+		s += ":VerifyDNSLength"
+	}
+	return s
+}
+
+var (
+	// Punycode is a Profile that does raw punycode processing with a minimum
+	// of validation.
+	Punycode *Profile = punycode
+
+	// Lookup is the recommended profile for looking up domain names, according
+	// to Section 5 of RFC 5891. The exact configuration of this profile may
+	// change over time.
+	Lookup *Profile = lookup
+
+	// Display is the recommended profile for displaying domain names.
+	// The configuration of this profile may change over time.
+	Display *Profile = display
+
+	// Registration is the recommended profile for checking whether a given
+	// IDN is valid for registration, according to Section 4 of RFC 5891.
+	Registration *Profile = registration
+
+	punycode = &Profile{}
+	lookup   = &Profile{options{
+		transitional:      true,
+		useSTD3Rules:      true,
+		validateLabels:    true,
+		removeLeadingDots: true,
+		trie:              trie,
+		fromPuny:          validateFromPunycode,
+		mapping:           validateAndMap,
+		bidirule:          bidirule.ValidString,
+	}}
+	display = &Profile{options{
+		useSTD3Rules:      true,
+		validateLabels:    true,
+		removeLeadingDots: true,
+		trie:              trie,
+		fromPuny:          validateFromPunycode,
+		mapping:           validateAndMap,
+		bidirule:          bidirule.ValidString,
+	}}
+	registration = &Profile{options{
+		useSTD3Rules:    true,
+		validateLabels:  true,
+		verifyDNSLength: true,
+		trie:            trie,
+		fromPuny:        validateFromPunycode,
+		mapping:         validateRegistration,
+		bidirule:        bidirule.ValidString,
+	}}
+
+	// TODO: profiles
+	// Register: recommended for approving domain names: don't do any mappings
+	// but rather reject on invalid input. Bundle or block deviation characters.
+)
+
+type labelError struct{ label, code_ string }
+
+func (e labelError) code() string { return e.code_ }
+func (e labelError) Error() string {
+	return fmt.Sprintf("idna: invalid label %q", e.label)
+}
+
+type runeError rune
+
+func (e runeError) code() string { return "P1" }
+func (e runeError) Error() string {
+	return fmt.Sprintf("idna: disallowed rune %U", e)
+}
+
+// process implements the algorithm described in section 4 of UTS #46,
+// see https://www.unicode.org/reports/tr46.
+func (p *Profile) process(s string, toASCII bool) (string, error) {
+	var err error
+	if p.mapping != nil {
+		s, err = p.mapping(p, s)
+	}
+	// Remove leading empty labels.
+	if p.removeLeadingDots {
+		for ; len(s) > 0 && s[0] == '.'; s = s[1:] {
+		}
+	}
+	// It seems like we should only create this error on ToASCII, but the
+	// UTS 46 conformance tests suggests we should always check this.
+	if err == nil && p.verifyDNSLength && s == "" {
+		err = &labelError{s, "A4"}
+	}
+	labels := labelIter{orig: s}
+	for ; !labels.done(); labels.next() {
+		label := labels.label()
+		if label == "" {
+			// Empty labels are not okay. The label iterator skips the last
+			// label if it is empty.
+			if err == nil && p.verifyDNSLength {
+				err = &labelError{s, "A4"}
+			}
+			continue
+		}
+		if strings.HasPrefix(label, acePrefix) {
+			u, err2 := decode(label[len(acePrefix):])
+			if err2 != nil {
+				if err == nil {
+					err = err2
+				}
+				// Spec says keep the old label.
+				continue
+			}
+			labels.set(u)
+			if err == nil && p.validateLabels {
+				err = p.fromPuny(p, u)
+			}
+			if err == nil {
+				// This should be called on NonTransitional, according to the
+				// spec, but that currently does not have any effect. Use the
+				// original profile to preserve options.
+				err = p.validateLabel(u)
+			}
+		} else if err == nil {
+			err = p.validateLabel(label)
+		}
+	}
+	if toASCII {
+		for labels.reset(); !labels.done(); labels.next() {
+			label := labels.label()
+			if !ascii(label) {
+				a, err2 := encode(acePrefix, label)
+				if err == nil {
+					err = err2
+				}
+				label = a
+				labels.set(a)
+			}
+			n := len(label)
+			if p.verifyDNSLength && err == nil && (n == 0 || n > 63) {
+				err = &labelError{label, "A4"}
+			}
+		}
+	}
+	s = labels.result()
+	if toASCII && p.verifyDNSLength && err == nil {
+		// Compute the length of the domain name minus the root label and its dot.
+		n := len(s)
+		if n > 0 && s[n-1] == '.' {
+			n--
+		}
+		if len(s) < 1 || n > 253 {
+			err = &labelError{s, "A4"}
+		}
+	}
+	return s, err
+}
+
+func normalize(p *Profile, s string) (string, error) {
+	return norm.NFC.String(s), nil
+}
+
+func validateRegistration(p *Profile, s string) (string, error) {
+	if !norm.NFC.IsNormalString(s) {
+		return s, &labelError{s, "V1"}
+	}
+	for i := 0; i < len(s); {
+		v, sz := trie.lookupString(s[i:])
+		// Copy bytes not copied so far.
+		switch p.simplify(info(v).category()) {
+		// TODO: handle the NV8 defined in the Unicode idna data set to allow
+		// for strict conformance to IDNA2008.
+		case valid, deviation:
+		case disallowed, mapped, unknown, ignored:
+			r, _ := utf8.DecodeRuneInString(s[i:])
+			return s, runeError(r)
+		}
+		i += sz
+	}
+	return s, nil
+}
+
+func validateAndMap(p *Profile, s string) (string, error) {
+	var (
+		err error
+		b   []byte
+		k   int
+	)
+	for i := 0; i < len(s); {
+		v, sz := trie.lookupString(s[i:])
+		start := i
+		i += sz
+		// Copy bytes not copied so far.
+		switch p.simplify(info(v).category()) {
+		case valid:
+			continue
+		case disallowed:
+			if err == nil {
+				r, _ := utf8.DecodeRuneInString(s[start:])
+				err = runeError(r)
+			}
+			continue
+		case mapped, deviation:
+			b = append(b, s[k:start]...)
+			b = info(v).appendMapping(b, s[start:i])
+		case ignored:
+			b = append(b, s[k:start]...)
+			// drop the rune
+		case unknown:
+			b = append(b, s[k:start]...)
+			b = append(b, "\ufffd"...)
+		}
+		k = i
+	}
+	if k == 0 {
+		// No changes so far.
+		s = norm.NFC.String(s)
+	} else {
+		b = append(b, s[k:]...)
+		if norm.NFC.QuickSpan(b) != len(b) {
+			b = norm.NFC.Bytes(b)
+		}
+		// TODO: the punycode converters require strings as input.
+		s = string(b)
+	}
+	return s, err
+}
+
+// A labelIter allows iterating over domain name labels.
+type labelIter struct {
+	orig     string
+	slice    []string
+	curStart int
+	curEnd   int
+	i        int
+}
+
+func (l *labelIter) reset() {
+	l.curStart = 0
+	l.curEnd = 0
+	l.i = 0
+}
+
+func (l *labelIter) done() bool {
+	return l.curStart >= len(l.orig)
+}
+
+func (l *labelIter) result() string {
+	if l.slice != nil {
+		return strings.Join(l.slice, ".")
+	}
+	return l.orig
+}
+
+func (l *labelIter) label() string {
+	if l.slice != nil {
+		return l.slice[l.i]
+	}
+	p := strings.IndexByte(l.orig[l.curStart:], '.')
+	l.curEnd = l.curStart + p
+	if p == -1 {
+		l.curEnd = len(l.orig)
+	}
+	return l.orig[l.curStart:l.curEnd]
+}
+
+// next sets the value to the next label. It skips the last label if it is empty.
+func (l *labelIter) next() {
+	l.i++
+	if l.slice != nil {
+		if l.i >= len(l.slice) || l.i == len(l.slice)-1 && l.slice[l.i] == "" {
+			l.curStart = len(l.orig)
+		}
+	} else {
+		l.curStart = l.curEnd + 1
+		if l.curStart == len(l.orig)-1 && l.orig[l.curStart] == '.' {
+			l.curStart = len(l.orig)
+		}
+	}
+}
+
+func (l *labelIter) set(s string) {
+	if l.slice == nil {
+		l.slice = strings.Split(l.orig, ".")
+	}
+	l.slice[l.i] = s
+}
+
+// acePrefix is the ASCII Compatible Encoding prefix.
+const acePrefix = "xn--"
+
+func (p *Profile) simplify(cat category) category {
+	switch cat {
+	case disallowedSTD3Mapped:
+		if p.useSTD3Rules {
+			cat = disallowed
+		} else {
+			cat = mapped
+		}
+	case disallowedSTD3Valid:
+		if p.useSTD3Rules {
+			cat = disallowed
+		} else {
+			cat = valid
+		}
+	case deviation:
+		if !p.transitional {
+			cat = valid
+		}
+	case validNV8, validXV8:
+		// TODO: handle V2008
+		cat = valid
+	}
+	return cat
+}
+
+func validateFromPunycode(p *Profile, s string) error {
+	if !norm.NFC.IsNormalString(s) {
+		return &labelError{s, "V1"}
+	}
+	for i := 0; i < len(s); {
+		v, sz := trie.lookupString(s[i:])
+		if c := p.simplify(info(v).category()); c != valid && c != deviation {
+			return &labelError{s, "V6"}
+		}
+		i += sz
+	}
+	return nil
+}
+
+const (
+	zwnj = "\u200c"
+	zwj  = "\u200d"
+)
+
+type joinState int8
+
+const (
+	stateStart joinState = iota
+	stateVirama
+	stateBefore
+	stateBeforeVirama
+	stateAfter
+	stateFAIL
+)
+
+var joinStates = [][numJoinTypes]joinState{
+	stateStart: {
+		joiningL:   stateBefore,
+		joiningD:   stateBefore,
+		joinZWNJ:   stateFAIL,
+		joinZWJ:    stateFAIL,
+		joinVirama: stateVirama,
+	},
+	stateVirama: {
+		joiningL: stateBefore,
+		joiningD: stateBefore,
+	},
+	stateBefore: {
+		joiningL:   stateBefore,
+		joiningD:   stateBefore,
+		joiningT:   stateBefore,
+		joinZWNJ:   stateAfter,
+		joinZWJ:    stateFAIL,
+		joinVirama: stateBeforeVirama,
+	},
+	stateBeforeVirama: {
+		joiningL: stateBefore,
+		joiningD: stateBefore,
+		joiningT: stateBefore,
+	},
+	stateAfter: {
+		joiningL:   stateFAIL,
+		joiningD:   stateBefore,
+		joiningT:   stateAfter,
+		joiningR:   stateStart,
+		joinZWNJ:   stateFAIL,
+		joinZWJ:    stateFAIL,
+		joinVirama: stateAfter, // no-op as we can't accept joiners here
+	},
+	stateFAIL: {
+		0:          stateFAIL,
+		joiningL:   stateFAIL,
+		joiningD:   stateFAIL,
+		joiningT:   stateFAIL,
+		joiningR:   stateFAIL,
+		joinZWNJ:   stateFAIL,
+		joinZWJ:    stateFAIL,
+		joinVirama: stateFAIL,
+	},
+}
+
+// validateLabel validates the criteria from Section 4.1. Item 1, 4, and 6 are
+// already implicitly satisfied by the overall implementation.
+func (p *Profile) validateLabel(s string) error {
+	if s == "" {
+		if p.verifyDNSLength {
+			return &labelError{s, "A4"}
+		}
+		return nil
+	}
+	if p.bidirule != nil && !p.bidirule(s) {
+		return &labelError{s, "B"}
+	}
+	if !p.validateLabels {
+		return nil
+	}
+	trie := p.trie // p.validateLabels is only set if trie is set.
+	if len(s) > 4 && s[2] == '-' && s[3] == '-' {
+		return &labelError{s, "V2"}
+	}
+	if s[0] == '-' || s[len(s)-1] == '-' {
+		return &labelError{s, "V3"}
+	}
+	// TODO: merge the use of this in the trie.
+	v, sz := trie.lookupString(s)
+	x := info(v)
+	if x.isModifier() {
+		return &labelError{s, "V5"}
+	}
+	// Quickly return in the absence of zero-width (non) joiners.
+	if strings.Index(s, zwj) == -1 && strings.Index(s, zwnj) == -1 {
+		return nil
+	}
+	st := stateStart
+	for i := 0; ; {
+		jt := x.joinType()
+		if s[i:i+sz] == zwj {
+			jt = joinZWJ
+		} else if s[i:i+sz] == zwnj {
+			jt = joinZWNJ
+		}
+		st = joinStates[st][jt]
+		if x.isViramaModifier() {
+			st = joinStates[st][joinVirama]
+		}
+		if i += sz; i == len(s) {
+			break
+		}
+		v, sz = trie.lookupString(s[i:])
+		x = info(v)
+	}
+	if st == stateFAIL || st == stateAfter {
+		return &labelError{s, "C"}
+	}
+	return nil
+}
+
+func ascii(s string) bool {
+	for i := 0; i < len(s); i++ {
+		if s[i] >= utf8.RuneSelf {
+			return false
+		}
+	}
+	return true
+}

vendor/golang.org/x/net/idna/punycode.go

+// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
+
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package idna
+
+// This file implements the Punycode algorithm from RFC 3492.
+
+import (
+	"math"
+	"strings"
+	"unicode/utf8"
+)
+
+// These parameter values are specified in section 5.
+//
+// All computation is done with int32s, so that overflow behavior is identical
+// regardless of whether int is 32-bit or 64-bit.
+const (
+	base        int32 = 36
+	damp        int32 = 700
+	initialBias int32 = 72
+	initialN    int32 = 128
+	skew        int32 = 38
+	tmax        int32 = 26
+	tmin        int32 = 1
+)
+
+func punyError(s string) error { return &labelError{s, "A3"} }
+
+// decode decodes a string as specified in section 6.2.
+func decode(encoded string) (string, error) {
+	if encoded == "" {
+		return "", nil
+	}
+	pos := 1 + strings.LastIndex(encoded, "-")
+	if pos == 1 {
+		return "", punyError(encoded)
+	}
+	if pos == len(encoded) {
+		return encoded[:len(encoded)-1], nil
+	}
+	output := make([]rune, 0, len(encoded))
+	if pos != 0 {
+		for _, r := range encoded[:pos-1] {
+			output = append(output, r)
+		}
+	}
+	i, n, bias := int32(0), initialN, initialBias
+	for pos < len(encoded) {
+		oldI, w := i, int32(1)
+		for k := base; ; k += base {
+			if pos == len(encoded) {
+				return "", punyError(encoded)
+			}
+			digit, ok := decodeDigit(encoded[pos])
+			if !ok {
+				return "", punyError(encoded)
+			}
+			pos++
+			i += digit * w
+			if i < 0 {
+				return "", punyError(encoded)
+			}
+			t := k - bias
+			if t < tmin {
+				t = tmin
+			} else if t > tmax {
+				t = tmax
+			}
+			if digit < t {
+				break
+			}
+			w *= base - t
+			if w >= math.MaxInt32/base {
+				return "", punyError(encoded)
+			}
+		}
+		x := int32(len(output) + 1)
+		bias = adapt(i-oldI, x, oldI == 0)
+		n += i / x
+		i %= x
+		if n > utf8.MaxRune || len(output) >= 1024 {
+			return "", punyError(encoded)
+		}
+		output = append(output, 0)
+		copy(output[i+1:], output[i:])
+		output[i] = n
+		i++
+	}
+	return string(output), nil
+}
+
+// encode encodes a string as specified in section 6.3 and prepends prefix to
+// the result.
+//
+// The "while h < length(input)" line in the specification becomes "for
+// remaining != 0" in the Go code, because len(s) in Go is in bytes, not runes.
+func encode(prefix, s string) (string, error) {
+	output := make([]byte, len(prefix), len(prefix)+1+2*len(s))
+	copy(output, prefix)
+	delta, n, bias := int32(0), initialN, initialBias
+	b, remaining := int32(0), int32(0)
+	for _, r := range s {
+		if r < 0x80 {
+			b++
+			output = append(output, byte(r))
+		} else {
+			remaining++
+		}
+	}
+	h := b
+	if b > 0 {
+		output = append(output, '-')
+	}
+	for remaining != 0 {
+		m := int32(0x7fffffff)
+		for _, r := range s {
+			if m > r && r >= n {
+				m = r
+			}
+		}
+		delta += (m - n) * (h + 1)
+		if delta < 0 {
+			return "", punyError(s)
+		}
+		n = m
+		for _, r := range s {
+			if r < n {
+				delta++
+				if delta < 0 {
+					return "", punyError(s)
+				}
+				continue
+			}
+			if r > n {
+				continue
+			}
+			q := delta
+			for k := base; ; k += base {
+				t := k - bias
+				if t < tmin {
+					t = tmin
+				} else if t > tmax {
+					t = tmax
+				}
+				if q < t {
+					break
+				}
+				output = append(output, encodeDigit(t+(q-t)%(base-t)))
+				q = (q - t) / (base - t)
+			}
+			output = append(output, encodeDigit(q))
+			bias = adapt(delta, h+1, h == b)
+			delta = 0
+			h++
+			remaining--
+		}
+		delta++
+		n++
+	}
+	return string(output), nil
+}
+
+func decodeDigit(x byte) (digit int32, ok bool) {
+	switch {
+	case '0' <= x && x <= '9':
+		return int32(x - ('0' - 26)), true
+	case 'A' <= x && x <= 'Z':
+		return int32(x - 'A'), true
+	case 'a' <= x && x <= 'z':
+		return int32(x - 'a'), true
+	}
+	return 0, false
+}
+
+func encodeDigit(digit int32) byte {
+	switch {
+	case 0 <= digit && digit < 26:
+		return byte(digit + 'a')
+	case 26 <= digit && digit < 36:
+		return byte(digit + ('0' - 26))
+	}
+	panic("idna: internal error in punycode encoding")
+}
+
+// adapt is the bias adaptation function specified in section 6.1.
+func adapt(delta, numPoints int32, firstTime bool) int32 {
+	if firstTime {
+		delta /= damp
+	} else {
+		delta /= 2
+	}
+	delta += delta / numPoints
+	k := int32(0)
+	for delta > ((base-tmin)*tmax)/2 {
+		delta /= base - tmin
+		k += base
+	}
+	return k + (base-tmin+1)*delta/(delta+skew)
+}

vendor/golang.org/x/net/idna/trie.go

+// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
+
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package idna
+
+// appendMapping appends the mapping for the respective rune. isMapped must be
+// true. A mapping is a categorization of a rune as defined in UTS #46.
+func (c info) appendMapping(b []byte, s string) []byte {
+	index := int(c >> indexShift)
+	if c&xorBit == 0 {
+		s := mappings[index:]
+		return append(b, s[1:s[0]+1]...)
+	}
+	b = append(b, s...)
+	if c&inlineXOR == inlineXOR {
+		// TODO: support and handle two-byte inline masks
+		b[len(b)-1] ^= byte(index)
+	} else {
+		for p := len(b) - int(xorData[index]); p < len(b); p++ {
+			index++
+			b[p] ^= xorData[index]
+		}
+	}
+	return b
+}
+
+// Sparse block handling code.
+
+type valueRange struct {
+	value  uint16 // header: value:stride
+	lo, hi byte   // header: lo:n
+}
+
+type sparseBlocks struct {
+	values []valueRange
+	offset []uint16
+}
+
+var idnaSparse = sparseBlocks{
+	values: idnaSparseValues[:],
+	offset: idnaSparseOffset[:],
+}
+
+// Don't use newIdnaTrie to avoid unconditional linking in of the table.
+var trie = &idnaTrie{}
+
+// lookup determines the type of block n and looks up the value for b.
+// For n < t.cutoff, the block is a simple lookup table. Otherwise, the block
+// is a list of ranges with an accompanying value. Given a matching range r,
+// the value for b is by r.value + (b - r.lo) * stride.
+func (t *sparseBlocks) lookup(n uint32, b byte) uint16 {
+	offset := t.offset[n]
+	header := t.values[offset]
+	lo := offset + 1
+	hi := lo + uint16(header.lo)
+	for lo < hi {
+		m := lo + (hi-lo)/2
+		r := t.values[m]
+		if r.lo <= b && b <= r.hi {
+			return r.value + uint16(b-r.lo)*header.value
+		}
+		if b < r.lo {
+			hi = m
+		} else {
+			lo = m + 1
+		}
+	}
+	return 0
+}

vendor/golang.org/x/net/idna/trieval.go

+// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
+
+package idna
+
+// This file contains definitions for interpreting the trie value of the idna
+// trie generated by "go run gen*.go". It is shared by both the generator
+// program and the resultant package. Sharing is achieved by the generator
+// copying gen_trieval.go to trieval.go and changing what's above this comment.
+
+// info holds information from the IDNA mapping table for a single rune. It is
+// the value returned by a trie lookup. In most cases, all information fits in
+// a 16-bit value. For mappings, this value may contain an index into a slice
+// with the mapped string. Such mappings can consist of the actual mapped value
+// or an XOR pattern to be applied to the bytes of the UTF8 encoding of the
+// input rune. This technique is used by the cases packages and reduces the
+// table size significantly.
+//
+// The per-rune values have the following format:
+//
+//   if mapped {
+//     if inlinedXOR {
+//       15..13 inline XOR marker
+//       12..11 unused
+//       10..3  inline XOR mask
+//     } else {
+//       15..3  index into xor or mapping table
+//     }
+//   } else {
+//       15..14 unused
+//       13     mayNeedNorm
+//       12..11 attributes
+//       10..8  joining type
+//        7..3  category type
+//   }
+//      2  use xor pattern
+//   1..0  mapped category
+//
+// See the definitions below for a more detailed description of the various
+// bits.
+type info uint16
+
+const (
+	catSmallMask = 0x3
+	catBigMask   = 0xF8
+	indexShift   = 3
+	xorBit       = 0x4    // interpret the index as an xor pattern
+	inlineXOR    = 0xE000 // These bits are set if the XOR pattern is inlined.
+
+	joinShift = 8
+	joinMask  = 0x07
+
+	// Attributes
+	attributesMask = 0x1800
+	viramaModifier = 0x1800
+	modifier       = 0x1000
+	rtl            = 0x0800
+
+	mayNeedNorm = 0x2000
+)
+
+// A category corresponds to a category defined in the IDNA mapping table.
+type category uint16
+
+const (
+	unknown              category = 0 // not currently defined in unicode.
+	mapped               category = 1
+	disallowedSTD3Mapped category = 2
+	deviation            category = 3
+)
+
+const (
+	valid               category = 0x08
+	validNV8            category = 0x18
+	validXV8            category = 0x28
+	disallowed          category = 0x40
+	disallowedSTD3Valid category = 0x80
+	ignored             category = 0xC0
+)
+
+// join types and additional rune information
+const (
+	joiningL = (iota + 1)
+	joiningD
+	joiningT
+	joiningR
+
+	//the following types are derived during processing
+	joinZWJ
+	joinZWNJ
+	joinVirama
+	numJoinTypes
+)
+
+func (c info) isMapped() bool {
+	return c&0x3 != 0
+}
+
+func (c info) category() category {
+	small := c & catSmallMask
+	if small != 0 {
+		return category(small)
+	}
+	return category(c & catBigMask)
+}
+
+func (c info) joinType() info {
+	if c.isMapped() {
+		return 0
+	}
+	return (c >> joinShift) & joinMask
+}
+
+func (c info) isModifier() bool {
+	return c&(modifier|catSmallMask) == modifier
+}
+
+func (c info) isViramaModifier() bool {
+	return c&(attributesMask|catSmallMask) == viramaModifier
+}

vendor/golang.org/x/text/AUTHORS

+# This source code refers to The Go Authors for copyright purposes.
+# The master list of authors is in the main Go distribution,
+# visible at http://tip.golang.org/AUTHORS.

vendor/golang.org/x/text/CONTRIBUTORS

+# This source code was written by the Go contributors.
+# The master list of contributors is in the main Go distribution,
+# visible at http://tip.golang.org/CONTRIBUTORS.

vendor/golang.org/x/text/LICENSE

+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/golang.org/x/text/PATENTS

+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

vendor/golang.org/x/text/secure/bidirule/bidirule.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package bidirule implements the Bidi Rule defined by RFC 5893.
+//
+// This package is under development. The API may change without notice and
+// without preserving backward compatibility.
+package bidirule
+
+import (
+	"errors"
+	"unicode/utf8"
+
+	"golang.org/x/text/transform"
+	"golang.org/x/text/unicode/bidi"
+)
+
+// This file contains an implementation of RFC 5893: Right-to-Left Scripts for
+// Internationalized Domain Names for Applications (IDNA)
+//
+// A label is an individual component of a domain name.  Labels are usually
+// shown separated by dots; for example, the domain name "www.example.com" is
+// composed of three labels: "www", "example", and "com".
+//
+// An RTL label is a label that contains at least one character of class R, AL,
+// or AN. An LTR label is any label that is not an RTL label.
+//
+// A "Bidi domain name" is a domain name that contains at least one RTL label.
+//
+//  The following guarantees can be made based on the above:
+//
+//  o  In a domain name consisting of only labels that satisfy the rule,
+//     the requirements of Section 3 are satisfied.  Note that even LTR
+//     labels and pure ASCII labels have to be tested.
+//
+//  o  In a domain name consisting of only LDH labels (as defined in the
+//     Definitions document [RFC5890]) and labels that satisfy the rule,
+//     the requirements of Section 3 are satisfied as long as a label
+//     that starts with an ASCII digit does not come after a
+//     right-to-left label.
+//
+//  No guarantee is given for other combinations.
+
+// ErrInvalid indicates a label is invalid according to the Bidi Rule.
+var ErrInvalid = errors.New("bidirule: failed Bidi Rule")
+
+type ruleState uint8
+
+const (
+	ruleInitial ruleState = iota
+	ruleLTR
+	ruleLTRFinal
+	ruleRTL
+	ruleRTLFinal
+	ruleInvalid
+)
+
+type ruleTransition struct {
+	next ruleState
+	mask uint16
+}
+
+var transitions = [...][2]ruleTransition{
+	// [2.1] The first character must be a character with Bidi property L, R, or
+	// AL. If it has the R or AL property, it is an RTL label; if it has the L
+	// property, it is an LTR label.
+	ruleInitial: {
+		{ruleLTRFinal, 1 << bidi.L},
+		{ruleRTLFinal, 1<<bidi.R | 1<<bidi.AL},
+	},
+	ruleRTL: {
+		// [2.3] In an RTL label, the end of the label must be a character with
+		// Bidi property R, AL, EN, or AN, followed by zero or more characters
+		// with Bidi property NSM.
+		{ruleRTLFinal, 1<<bidi.R | 1<<bidi.AL | 1<<bidi.EN | 1<<bidi.AN},
+
+		// [2.2] In an RTL label, only characters with the Bidi properties R,
+		// AL, AN, EN, ES, CS, ET, ON, BN, or NSM are allowed.
+		// We exclude the entries from [2.3]
+		{ruleRTL, 1<<bidi.ES | 1<<bidi.CS | 1<<bidi.ET | 1<<bidi.ON | 1<<bidi.BN | 1<<bidi.NSM},
+	},
+	ruleRTLFinal: {
+		// [2.3] In an RTL label, the end of the label must be a character with
+		// Bidi property R, AL, EN, or AN, followed by zero or more characters
+		// with Bidi property NSM.
+		{ruleRTLFinal, 1<<bidi.R | 1<<bidi.AL | 1<<bidi.EN | 1<<bidi.AN | 1<<bidi.NSM},
+
+		// [2.2] In an RTL label, only characters with the Bidi properties R,
+		// AL, AN, EN, ES, CS, ET, ON, BN, or NSM are allowed.
+		// We exclude the entries from [2.3] and NSM.
+		{ruleRTL, 1<<bidi.ES | 1<<bidi.CS | 1<<bidi.ET | 1<<bidi.ON | 1<<bidi.BN},
+	},
+	ruleLTR: {
+		// [2.6] In an LTR label, the end of the label must be a character with
+		// Bidi property L or EN, followed by zero or more characters with Bidi
+		// property NSM.
+		{ruleLTRFinal, 1<<bidi.L | 1<<bidi.EN},
+
+		// [2.5] In an LTR label, only characters with the Bidi properties L,
+		// EN, ES, CS, ET, ON, BN, or NSM are allowed.
+		// We exclude the entries from [2.6].
+		{ruleLTR, 1<<bidi.ES | 1<<bidi.CS | 1<<bidi.ET | 1<<bidi.ON | 1<<bidi.BN | 1<<bidi.NSM},
+	},
+	ruleLTRFinal: {
+		// [2.6] In an LTR label, the end of the label must be a character with
+		// Bidi property L or EN, followed by zero or more characters with Bidi
+		// property NSM.
+		{ruleLTRFinal, 1<<bidi.L | 1<<bidi.EN | 1<<bidi.NSM},
+
+		// [2.5] In an LTR label, only characters with the Bidi properties L,
+		// EN, ES, CS, ET, ON, BN, or NSM are allowed.
+		// We exclude the entries from [2.6].
+		{ruleLTR, 1<<bidi.ES | 1<<bidi.CS | 1<<bidi.ET | 1<<bidi.ON | 1<<bidi.BN},
+	},
+	ruleInvalid: {
+		{ruleInvalid, 0},
+		{ruleInvalid, 0},
+	},
+}
+
+// [2.4] In an RTL label, if an EN is present, no AN may be present, and
+// vice versa.
+const exclusiveRTL = uint16(1<<bidi.EN | 1<<bidi.AN)
+
+// From RFC 5893
+// An RTL label is a label that contains at least one character of type
+// R, AL, or AN.
+//
+// An LTR label is any label that is not an RTL label.
+
+// Direction reports the direction of the given label as defined by RFC 5893.
+// The Bidi Rule does not have to be applied to labels of the category
+// LeftToRight.
+func Direction(b []byte) bidi.Direction {
+	for i := 0; i < len(b); {
+		e, sz := bidi.Lookup(b[i:])
+		if sz == 0 {
+			i++
+		}
+		c := e.Class()
+		if c == bidi.R || c == bidi.AL || c == bidi.AN {
+			return bidi.RightToLeft
+		}
+		i += sz
+	}
+	return bidi.LeftToRight
+}
+
+// DirectionString reports the direction of the given label as defined by RFC
+// 5893. The Bidi Rule does not have to be applied to labels of the category
+// LeftToRight.
+func DirectionString(s string) bidi.Direction {
+	for i := 0; i < len(s); {
+		e, sz := bidi.LookupString(s[i:])
+		if sz == 0 {
+			i++
+			continue
+		}
+		c := e.Class()
+		if c == bidi.R || c == bidi.AL || c == bidi.AN {
+			return bidi.RightToLeft
+		}
+		i += sz
+	}
+	return bidi.LeftToRight
+}
+
+// Valid reports whether b conforms to the BiDi rule.
+func Valid(b []byte) bool {
+	var t Transformer
+	if n, ok := t.advance(b); !ok || n < len(b) {
+		return false
+	}
+	return t.isFinal()
+}
+
+// ValidString reports whether s conforms to the BiDi rule.
+func ValidString(s string) bool {
+	var t Transformer
+	if n, ok := t.advanceString(s); !ok || n < len(s) {
+		return false
+	}
+	return t.isFinal()
+}
+
+// New returns a Transformer that verifies that input adheres to the Bidi Rule.
+func New() *Transformer {
+	return &Transformer{}
+}
+
+// Transformer implements transform.Transform.
+type Transformer struct {
+	state  ruleState
+	hasRTL bool
+	seen   uint16
+}
+
+// A rule can only be violated for "Bidi Domain names", meaning if one of the
+// following categories has been observed.
+func (t *Transformer) isRTL() bool {
+	const isRTL = 1<<bidi.R | 1<<bidi.AL | 1<<bidi.AN
+	return t.seen&isRTL != 0
+}
+
+// Reset implements transform.Transformer.
+func (t *Transformer) Reset() { *t = Transformer{} }
+
+// Transform implements transform.Transformer. This Transformer has state and
+// needs to be reset between uses.
+func (t *Transformer) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+	if len(dst) < len(src) {
+		src = src[:len(dst)]
+		atEOF = false
+		err = transform.ErrShortDst
+	}
+	n, err1 := t.Span(src, atEOF)
+	copy(dst, src[:n])
+	if err == nil || err1 != nil && err1 != transform.ErrShortSrc {
+		err = err1
+	}
+	return n, n, err
+}
+
+// Span returns the first n bytes of src that conform to the Bidi rule.
+func (t *Transformer) Span(src []byte, atEOF bool) (n int, err error) {
+	if t.state == ruleInvalid && t.isRTL() {
+		return 0, ErrInvalid
+	}
+	n, ok := t.advance(src)
+	switch {
+	case !ok:
+		err = ErrInvalid
+	case n < len(src):
+		if !atEOF {
+			err = transform.ErrShortSrc
+			break
+		}
+		err = ErrInvalid
+	case !t.isFinal():
+		err = ErrInvalid
+	}
+	return n, err
+}
+
+// Precomputing the ASCII values decreases running time for the ASCII fast path
+// by about 30%.
+var asciiTable [128]bidi.Properties
+
+func init() {
+	for i := range asciiTable {
+		p, _ := bidi.LookupRune(rune(i))
+		asciiTable[i] = p
+	}
+}
+
+func (t *Transformer) advance(s []byte) (n int, ok bool) {
+	var e bidi.Properties
+	var sz int
+	for n < len(s) {
+		if s[n] < utf8.RuneSelf {
+			e, sz = asciiTable[s[n]], 1
+		} else {
+			e, sz = bidi.Lookup(s[n:])
+			if sz <= 1 {
+				if sz == 1 {
+					// We always consider invalid UTF-8 to be invalid, even if
+					// the string has not yet been determined to be RTL.
+					// TODO: is this correct?
+					return n, false
+				}
+				return n, true // incomplete UTF-8 encoding
+			}
+		}
+		// TODO: using CompactClass would result in noticeable speedup.
+		// See unicode/bidi/prop.go:Properties.CompactClass.
+		c := uint16(1 << e.Class())
+		t.seen |= c
+		if t.seen&exclusiveRTL == exclusiveRTL {
+			t.state = ruleInvalid
+			return n, false
+		}
+		switch tr := transitions[t.state]; {
+		case tr[0].mask&c != 0:
+			t.state = tr[0].next
+		case tr[1].mask&c != 0:
+			t.state = tr[1].next
+		default:
+			t.state = ruleInvalid
+			if t.isRTL() {
+				return n, false
+			}
+		}
+		n += sz
+	}
+	return n, true
+}
+
+func (t *Transformer) advanceString(s string) (n int, ok bool) {
+	var e bidi.Properties
+	var sz int
+	for n < len(s) {
+		if s[n] < utf8.RuneSelf {
+			e, sz = asciiTable[s[n]], 1
+		} else {
+			e, sz = bidi.LookupString(s[n:])
+			if sz <= 1 {
+				if sz == 1 {
+					return n, false // invalid UTF-8
+				}
+				return n, true // incomplete UTF-8 encoding
+			}
+		}
+		// TODO: using CompactClass results in noticeable speedup.
+		// See unicode/bidi/prop.go:Properties.CompactClass.
+		c := uint16(1 << e.Class())
+		t.seen |= c
+		if t.seen&exclusiveRTL == exclusiveRTL {
+			t.state = ruleInvalid
+			return n, false
+		}
+		switch tr := transitions[t.state]; {
+		case tr[0].mask&c != 0:
+			t.state = tr[0].next
+		case tr[1].mask&c != 0:
+			t.state = tr[1].next
+		default:
+			t.state = ruleInvalid
+			if t.isRTL() {
+				return n, false
+			}
+		}
+		n += sz
+	}
+	return n, true
+}

vendor/golang.org/x/text/secure/bidirule/bidirule10.0.0.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.10
+
+package bidirule
+
+func (t *Transformer) isFinal() bool {
+	return t.state == ruleLTRFinal || t.state == ruleRTLFinal || t.state == ruleInitial
+}

vendor/golang.org/x/text/secure/bidirule/bidirule9.0.0.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !go1.10
+
+package bidirule
+
+func (t *Transformer) isFinal() bool {
+	if !t.isRTL() {
+		return true
+	}
+	return t.state == ruleLTRFinal || t.state == ruleRTLFinal || t.state == ruleInitial
+}

vendor/golang.org/x/text/unicode/bidi/bidi.go

+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:generate go run gen.go gen_trieval.go gen_ranges.go
+
+// Package bidi contains functionality for bidirectional text support.
+//
+// See http://www.unicode.org/reports/tr9.
+//
+// NOTE: UNDER CONSTRUCTION. This API may change in backwards incompatible ways
+// and without notice.
+package bidi // import "golang.org/x/text/unicode/bidi"
+
+// TODO:
+// The following functionality would not be hard to implement, but hinges on
+// the definition of a Segmenter interface. For now this is up to the user.
+// - Iterate over paragraphs
+// - Segmenter to iterate over runs directly from a given text.
+// Also:
+// - Transformer for reordering?
+// - Transformer (validator, really) for Bidi Rule.
+
+// This API tries to avoid dealing with embedding levels for now. Under the hood
+// these will be computed, but the question is to which extent the user should
+// know they exist. We should at some point allow the user to specify an
+// embedding hierarchy, though.
+
+// A Direction indicates the overall flow of text.
+type Direction int
+
+const (
+	// LeftToRight indicates the text contains no right-to-left characters and
+	// that either there are some left-to-right characters or the option
+	// DefaultDirection(LeftToRight) was passed.
+	LeftToRight Direction = iota
+
+	// RightToLeft indicates the text contains no left-to-right characters and
+	// that either there are some right-to-left characters or the option
+	// DefaultDirection(RightToLeft) was passed.
+	RightToLeft
+
+	// Mixed indicates text contains both left-to-right and right-to-left
+	// characters.
+	Mixed
+
+	// Neutral means that text contains no left-to-right and right-to-left
+	// characters and that no default direction has been set.
+	Neutral
+)
+
+type options struct{}
+
+// An Option is an option for Bidi processing.
+type Option func(*options)
+
+// ICU allows the user to define embedding levels. This may be used, for example,
+// to use hierarchical structure of markup languages to define embeddings.
+// The following option may be a way to expose this functionality in this API.
+// // LevelFunc sets a function that associates nesting levels with the given text.
+// // The levels function will be called with monotonically increasing values for p.
+// func LevelFunc(levels func(p int) int) Option {
+// 	panic("unimplemented")
+// }
+
+// DefaultDirection sets the default direction for a Paragraph. The direction is
+// overridden if the text contains directional characters.
+func DefaultDirection(d Direction) Option {
+	panic("unimplemented")
+}
+
+// A Paragraph holds a single Paragraph for Bidi processing.
+type Paragraph struct {
+	// buffers
+}
+
+// SetBytes configures p for the given paragraph text. It replaces text
+// previously set by SetBytes or SetString. If b contains a paragraph separator
+// it will only process the first paragraph and report the number of bytes
+// consumed from b including this separator. Error may be non-nil if options are
+// given.
+func (p *Paragraph) SetBytes(b []byte, opts ...Option) (n int, err error) {
+	panic("unimplemented")
+}
+
+// SetString configures p for the given paragraph text. It replaces text
+// previously set by SetBytes or SetString. If b contains a paragraph separator
+// it will only process the first paragraph and report the number of bytes
+// consumed from b including this separator. Error may be non-nil if options are
+// given.
+func (p *Paragraph) SetString(s string, opts ...Option) (n int, err error) {
+	panic("unimplemented")
+}
+
+// IsLeftToRight reports whether the principle direction of rendering for this
+// paragraphs is left-to-right. If this returns false, the principle direction
+// of rendering is right-to-left.
+func (p *Paragraph) IsLeftToRight() bool {
+	panic("unimplemented")
+}
+
+// Direction returns the direction of the text of this paragraph.
+//
+// The direction may be LeftToRight, RightToLeft, Mixed, or Neutral.
+func (p *Paragraph) Direction() Direction {
+	panic("unimplemented")
+}
+
+// RunAt reports the Run at the given position of the input text.
+//
+// This method can be used for computing line breaks on paragraphs.
+func (p *Paragraph) RunAt(pos int) Run {
+	panic("unimplemented")
+}
+
+// Order computes the visual ordering of all the runs in a Paragraph.
+func (p *Paragraph) Order() (Ordering, error) {
+	panic("unimplemented")
+}
+
+// Line computes the visual ordering of runs for a single line starting and
+// ending at the given positions in the original text.
+func (p *Paragraph) Line(start, end int) (Ordering, error) {
+	panic("unimplemented")
+}
+
+// An Ordering holds the computed visual order of runs of a Paragraph. Calling
+// SetBytes or SetString on the originating Paragraph invalidates an Ordering.
+// The methods of an Ordering should only be called by one goroutine at a time.
+type Ordering struct{}
+
+// Direction reports the directionality of the runs.
+//
+// The direction may be LeftToRight, RightToLeft, Mixed, or Neutral.
+func (o *Ordering) Direction() Direction {
+	panic("unimplemented")
+}
+
+// NumRuns returns the number of runs.
+func (o *Ordering) NumRuns() int {
+	panic("unimplemented")
+}
+
+// Run returns the ith run within the ordering.
+func (o *Ordering) Run(i int) Run {
+	panic("unimplemented")
+}
+
+// TODO: perhaps with options.
+// // Reorder creates a reader that reads the runes in visual order per character.
+// // Modifiers remain after the runes they modify.
+// func (l *Runs) Reorder() io.Reader {
+// 	panic("unimplemented")
+// }
+
+// A Run is a continuous sequence of characters of a single direction.
+type Run struct {
+}
+
+// String returns the text of the run in its original order.
+func (r *Run) String() string {
+	panic("unimplemented")
+}
+
+// Bytes returns the text of the run in its original order.
+func (r *Run) Bytes() []byte {
+	panic("unimplemented")
+}
+
+// TODO: methods for
+// - Display order
+// - headers and footers
+// - bracket replacement.
+
+// Direction reports the direction of the run.
+func (r *Run) Direction() Direction {
+	panic("unimplemented")
+}
+
+// Position of the Run within the text passed to SetBytes or SetString of the
+// originating Paragraph value.
+func (r *Run) Pos() (start, end int) {
+	panic("unimplemented")
+}
+
+// AppendReverse reverses the order of characters of in, appends them to out,
+// and returns the result. Modifiers will still follow the runes they modify.
+// Brackets are replaced with their counterparts.
+func AppendReverse(out, in []byte) []byte {
+	panic("unimplemented")
+}
+
+// ReverseString reverses the order of characters in s and returns a new string.
+// Modifiers will still follow the runes they modify. Brackets are replaced with
+// their counterparts.
+func ReverseString(s string) string {
+	panic("unimplemented")
+}

vendor/golang.org/x/text/unicode/bidi/bracket.go

+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bidi
+
+import (
+	"container/list"
+	"fmt"
+	"sort"
+)
+
+// This file contains a port of the reference implementation of the
+// Bidi Parentheses Algorithm:
+// http://www.unicode.org/Public/PROGRAMS/BidiReferenceJava/BidiPBAReference.java
+//
+// The implementation in this file covers definitions BD14-BD16 and rule N0
+// of UAX#9.
+//
+// Some preprocessing is done for each rune before data is passed to this
+// algorithm:
+//  - opening and closing brackets are identified
+//  - a bracket pair type, like '(' and ')' is assigned a unique identifier that
+//    is identical for the opening and closing bracket. It is left to do these
+//    mappings.
+//  - The BPA algorithm requires that bracket characters that are canonical
+//    equivalents of each other be able to be substituted for each other.
+//    It is the responsibility of the caller to do this canonicalization.
+//
+// In implementing BD16, this implementation departs slightly from the "logical"
+// algorithm defined in UAX#9. In particular, the stack referenced there
+// supports operations that go beyond a "basic" stack. An equivalent
+// implementation based on a linked list is used here.
+
+// Bidi_Paired_Bracket_Type
+// BD14. An opening paired bracket is a character whose
+// Bidi_Paired_Bracket_Type property value is Open.
+//
+// BD15. A closing paired bracket is a character whose
+// Bidi_Paired_Bracket_Type property value is Close.
+type bracketType byte
+
+const (
+	bpNone bracketType = iota
+	bpOpen
+	bpClose
+)
+
+// bracketPair holds a pair of index values for opening and closing bracket
+// location of a bracket pair.
+type bracketPair struct {
+	opener int
+	closer int
+}
+
+func (b *bracketPair) String() string {
+	return fmt.Sprintf("(%v, %v)", b.opener, b.closer)
+}
+
+// bracketPairs is a slice of bracketPairs with a sort.Interface implementation.
+type bracketPairs []bracketPair
+
+func (b bracketPairs) Len() int           { return len(b) }
+func (b bracketPairs) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
+func (b bracketPairs) Less(i, j int) bool { return b[i].opener < b[j].opener }
+
+// resolvePairedBrackets runs the paired bracket part of the UBA algorithm.
+//
+// For each rune, it takes the indexes into the original string, the class the
+// bracket type (in pairTypes) and the bracket identifier (pairValues). It also
+// takes the direction type for the start-of-sentence and the embedding level.
+//
+// The identifiers for bracket types are the rune of the canonicalized opening
+// bracket for brackets (open or close) or 0 for runes that are not brackets.
+func resolvePairedBrackets(s *isolatingRunSequence) {
+	p := bracketPairer{
+		sos:              s.sos,
+		openers:          list.New(),
+		codesIsolatedRun: s.types,
+		indexes:          s.indexes,
+	}
+	dirEmbed := L
+	if s.level&1 != 0 {
+		dirEmbed = R
+	}
+	p.locateBrackets(s.p.pairTypes, s.p.pairValues)
+	p.resolveBrackets(dirEmbed, s.p.initialTypes)
+}
+
+type bracketPairer struct {
+	sos Class // direction corresponding to start of sequence
+
+	// The following is a restatement of BD 16 using non-algorithmic language.
+	//
+	// A bracket pair is a pair of characters consisting of an opening
+	// paired bracket and a closing paired bracket such that the
+	// Bidi_Paired_Bracket property value of the former equals the latter,
+	// subject to the following constraints.
+	// - both characters of a pair occur in the same isolating run sequence
+	// - the closing character of a pair follows the opening character
+	// - any bracket character can belong at most to one pair, the earliest possible one
+	// - any bracket character not part of a pair is treated like an ordinary character
+	// - pairs may nest properly, but their spans may not overlap otherwise
+
+	// Bracket characters with canonical decompositions are supposed to be
+	// treated as if they had been normalized, to allow normalized and non-
+	// normalized text to give the same result. In this implementation that step
+	// is pushed out to the caller. The caller has to ensure that the pairValue
+	// slices contain the rune of the opening bracket after normalization for
+	// any opening or closing bracket.
+
+	openers *list.List // list of positions for opening brackets
+
+	// bracket pair positions sorted by location of opening bracket
+	pairPositions bracketPairs
+
+	codesIsolatedRun []Class // directional bidi codes for an isolated run
+	indexes          []int   // array of index values into the original string
+
+}
+
+// matchOpener reports whether characters at given positions form a matching
+// bracket pair.
+func (p *bracketPairer) matchOpener(pairValues []rune, opener, closer int) bool {
+	return pairValues[p.indexes[opener]] == pairValues[p.indexes[closer]]
+}
+
+const maxPairingDepth = 63
+
+// locateBrackets locates matching bracket pairs according to BD16.
+//
+// This implementation uses a linked list instead of a stack, because, while
+// elements are added at the front (like a push) they are not generally removed
+// in atomic 'pop' operations, reducing the benefit of the stack archetype.
+func (p *bracketPairer) locateBrackets(pairTypes []bracketType, pairValues []rune) {
+	// traverse the run
+	// do that explicitly (not in a for-each) so we can record position
+	for i, index := range p.indexes {
+
+		// look at the bracket type for each character
+		if pairTypes[index] == bpNone || p.codesIsolatedRun[i] != ON {
+			// continue scanning
+			continue
+		}
+		switch pairTypes[index] {
+		case bpOpen:
+			// check if maximum pairing depth reached
+			if p.openers.Len() == maxPairingDepth {
+				p.openers.Init()
+				return
+			}
+			// remember opener location, most recent first
+			p.openers.PushFront(i)
+
+		case bpClose:
+			// see if there is a match
+			count := 0
+			for elem := p.openers.Front(); elem != nil; elem = elem.Next() {
+				count++
+				opener := elem.Value.(int)
+				if p.matchOpener(pairValues, opener, i) {
+					// if the opener matches, add nested pair to the ordered list
+					p.pairPositions = append(p.pairPositions, bracketPair{opener, i})
+					// remove up to and including matched opener
+					for ; count > 0; count-- {
+						p.openers.Remove(p.openers.Front())
+					}
+					break
+				}
+			}
+			sort.Sort(p.pairPositions)
+			// if we get here, the closing bracket matched no openers
+			// and gets ignored
+		}
+	}
+}
+
+// Bracket pairs within an isolating run sequence are processed as units so
+// that both the opening and the closing paired bracket in a pair resolve to
+// the same direction.
+//
+// N0. Process bracket pairs in an isolating run sequence sequentially in
+// the logical order of the text positions of the opening paired brackets
+// using the logic given below. Within this scope, bidirectional types EN
+// and AN are treated as R.
+//
+// Identify the bracket pairs in the current isolating run sequence
+// according to BD16. For each bracket-pair element in the list of pairs of
+// text positions:
+//
+// a Inspect the bidirectional types of the characters enclosed within the
+// bracket pair.
+//
+// b If any strong type (either L or R) matching the embedding direction is
+// found, set the type for both brackets in the pair to match the embedding
+// direction.
+//
+// o [ e ] o -> o e e e o
+//
+// o [ o e ] -> o e o e e
+//
+// o [ NI e ] -> o e NI e e
+//
+// c Otherwise, if a strong type (opposite the embedding direction) is
+// found, test for adjacent strong types as follows: 1 First, check
+// backwards before the opening paired bracket until the first strong type
+// (L, R, or sos) is found. If that first preceding strong type is opposite
+// the embedding direction, then set the type for both brackets in the pair
+// to that type. 2 Otherwise, set the type for both brackets in the pair to
+// the embedding direction.
+//
+// o [ o ] e -> o o o o e
+//
+// o [ o NI ] o -> o o o NI o o
+//
+// e [ o ] o -> e e o e o
+//
+// e [ o ] e -> e e o e e
+//
+// e ( o [ o ] NI ) e -> e e o o o o NI e e
+//
+// d Otherwise, do not set the type for the current bracket pair. Note that
+// if the enclosed text contains no strong types the paired brackets will
+// both resolve to the same level when resolved individually using rules N1
+// and N2.
+//
+// e ( NI ) o -> e ( NI ) o
+
+// getStrongTypeN0 maps character's directional code to strong type as required
+// by rule N0.
+//
+// TODO: have separate type for "strong" directionality.
+func (p *bracketPairer) getStrongTypeN0(index int) Class {
+	switch p.codesIsolatedRun[index] {
+	// in the scope of N0, number types are treated as R
+	case EN, AN, AL, R:
+		return R
+	case L:
+		return L
+	default:
+		return ON
+	}
+}
+
+// classifyPairContent reports the strong types contained inside a Bracket Pair,
+// assuming the given embedding direction.
+//
+// It returns ON if no strong type is found. If a single strong type is found,
+// it returns this this type. Otherwise it returns the embedding direction.
+//
+// TODO: use separate type for "strong" directionality.
+func (p *bracketPairer) classifyPairContent(loc bracketPair, dirEmbed Class) Class {
+	dirOpposite := ON
+	for i := loc.opener + 1; i < loc.closer; i++ {
+		dir := p.getStrongTypeN0(i)
+		if dir == ON {
+			continue
+		}
+		if dir == dirEmbed {
+			return dir // type matching embedding direction found
+		}
+		dirOpposite = dir
+	}
+	// return ON if no strong type found, or class opposite to dirEmbed
+	return dirOpposite
+}
+
+// classBeforePair determines which strong types are present before a Bracket
+// Pair. Return R or L if strong type found, otherwise ON.
+func (p *bracketPairer) classBeforePair(loc bracketPair) Class {
+	for i := loc.opener - 1; i >= 0; i-- {
+		if dir := p.getStrongTypeN0(i); dir != ON {
+			return dir
+		}
+	}
+	// no strong types found, return sos
+	return p.sos
+}
+
+// assignBracketType implements rule N0 for a single bracket pair.
+func (p *bracketPairer) assignBracketType(loc bracketPair, dirEmbed Class, initialTypes []Class) {
+	// rule "N0, a", inspect contents of pair
+	dirPair := p.classifyPairContent(loc, dirEmbed)
+
+	// dirPair is now L, R, or N (no strong type found)
+
+	// the following logical tests are performed out of order compared to
+	// the statement of the rules but yield the same results
+	if dirPair == ON {
+		return // case "d" - nothing to do
+	}
+
+	if dirPair != dirEmbed {
+		// case "c": strong type found, opposite - check before (c.1)
+		dirPair = p.classBeforePair(loc)
+		if dirPair == dirEmbed || dirPair == ON {
+			// no strong opposite type found before - use embedding (c.2)
+			dirPair = dirEmbed
+		}
+	}
+	// else: case "b", strong type found matching embedding,
+	// no explicit action needed, as dirPair is already set to embedding
+	// direction
+
+	// set the bracket types to the type found
+	p.setBracketsToType(loc, dirPair, initialTypes)
+}
+
+func (p *bracketPairer) setBracketsToType(loc bracketPair, dirPair Class, initialTypes []Class) {
+	p.codesIsolatedRun[loc.opener] = dirPair
+	p.codesIsolatedRun[loc.closer] = dirPair
+
+	for i := loc.opener + 1; i < loc.closer; i++ {
+		index := p.indexes[i]
+		if initialTypes[index] != NSM {
+			break
+		}
+		p.codesIsolatedRun[i] = dirPair
+	}
+
+	for i := loc.closer + 1; i < len(p.indexes); i++ {
+		index := p.indexes[i]
+		if initialTypes[index] != NSM {
+			break
+		}
+		p.codesIsolatedRun[i] = dirPair
+	}
+}
+
+// resolveBrackets implements rule N0 for a list of pairs.
+func (p *bracketPairer) resolveBrackets(dirEmbed Class, initialTypes []Class) {
+	for _, loc := range p.pairPositions {
+		p.assignBracketType(loc, dirEmbed, initialTypes)
+	}
+}

vendor/golang.org/x/text/unicode/bidi/prop.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bidi
+
+import "unicode/utf8"
+
+// Properties provides access to BiDi properties of runes.
+type Properties struct {
+	entry uint8
+	last  uint8
+}
+
+var trie = newBidiTrie(0)
+
+// TODO: using this for bidirule reduces the running time by about 5%. Consider
+// if this is worth exposing or if we can find a way to speed up the Class
+// method.
+//
+// // CompactClass is like Class, but maps all of the BiDi control classes
+// // (LRO, RLO, LRE, RLE, PDF, LRI, RLI, FSI, PDI) to the class Control.
+// func (p Properties) CompactClass() Class {
+// 	return Class(p.entry & 0x0F)
+// }
+
+// Class returns the Bidi class for p.
+func (p Properties) Class() Class {
+	c := Class(p.entry & 0x0F)
+	if c == Control {
+		c = controlByteToClass[p.last&0xF]
+	}
+	return c
+}
+
+// IsBracket reports whether the rune is a bracket.
+func (p Properties) IsBracket() bool { return p.entry&0xF0 != 0 }
+
+// IsOpeningBracket reports whether the rune is an opening bracket.
+// IsBracket must return true.
+func (p Properties) IsOpeningBracket() bool { return p.entry&openMask != 0 }
+
+// TODO: find a better API and expose.
+func (p Properties) reverseBracket(r rune) rune {
+	return xorMasks[p.entry>>xorMaskShift] ^ r
+}
+
+var controlByteToClass = [16]Class{
+	0xD: LRO, // U+202D LeftToRightOverride,
+	0xE: RLO, // U+202E RightToLeftOverride,
+	0xA: LRE, // U+202A LeftToRightEmbedding,
+	0xB: RLE, // U+202B RightToLeftEmbedding,
+	0xC: PDF, // U+202C PopDirectionalFormat,
+	0x6: LRI, // U+2066 LeftToRightIsolate,
+	0x7: RLI, // U+2067 RightToLeftIsolate,
+	0x8: FSI, // U+2068 FirstStrongIsolate,
+	0x9: PDI, // U+2069 PopDirectionalIsolate,
+}
+
+// LookupRune returns properties for r.
+func LookupRune(r rune) (p Properties, size int) {
+	var buf [4]byte
+	n := utf8.EncodeRune(buf[:], r)
+	return Lookup(buf[:n])
+}
+
+// TODO: these lookup methods are based on the generated trie code. The returned
+// sizes have slightly different semantics from the generated code, in that it
+// always returns size==1 for an illegal UTF-8 byte (instead of the length
+// of the maximum invalid subsequence). Most Transformers, like unicode/norm,
+// leave invalid UTF-8 untouched, in which case it has performance benefits to
+// do so (without changing the semantics). Bidi requires the semantics used here
+// for the bidirule implementation to be compatible with the Go semantics.
+//  They ultimately should perhaps be adopted by all trie implementations, for
+// convenience sake.
+// This unrolled code also boosts performance of the secure/bidirule package by
+// about 30%.
+// So, to remove this code:
+//   - add option to trie generator to define return type.
+//   - always return 1 byte size for ill-formed UTF-8 runes.
+
+// Lookup returns properties for the first rune in s and the width in bytes of
+// its encoding. The size will be 0 if s does not hold enough bytes to complete
+// the encoding.
+func Lookup(s []byte) (p Properties, sz int) {
+	c0 := s[0]
+	switch {
+	case c0 < 0x80: // is ASCII
+		return Properties{entry: bidiValues[c0]}, 1
+	case c0 < 0xC2:
+		return Properties{}, 1
+	case c0 < 0xE0: // 2-byte UTF-8
+		if len(s) < 2 {
+			return Properties{}, 0
+		}
+		i := bidiIndex[c0]
+		c1 := s[1]
+		if c1 < 0x80 || 0xC0 <= c1 {
+			return Properties{}, 1
+		}
+		return Properties{entry: trie.lookupValue(uint32(i), c1)}, 2
+	case c0 < 0xF0: // 3-byte UTF-8
+		if len(s) < 3 {
+			return Properties{}, 0
+		}
+		i := bidiIndex[c0]
+		c1 := s[1]
+		if c1 < 0x80 || 0xC0 <= c1 {
+			return Properties{}, 1
+		}
+		o := uint32(i)<<6 + uint32(c1)
+		i = bidiIndex[o]
+		c2 := s[2]
+		if c2 < 0x80 || 0xC0 <= c2 {
+			return Properties{}, 1
+		}
+		return Properties{entry: trie.lookupValue(uint32(i), c2), last: c2}, 3
+	case c0 < 0xF8: // 4-byte UTF-8
+		if len(s) < 4 {
+			return Properties{}, 0
+		}
+		i := bidiIndex[c0]
+		c1 := s[1]
+		if c1 < 0x80 || 0xC0 <= c1 {
+			return Properties{}, 1
+		}
+		o := uint32(i)<<6 + uint32(c1)
+		i = bidiIndex[o]
+		c2 := s[2]
+		if c2 < 0x80 || 0xC0 <= c2 {
+			return Properties{}, 1
+		}
+		o = uint32(i)<<6 + uint32(c2)
+		i = bidiIndex[o]
+		c3 := s[3]
+		if c3 < 0x80 || 0xC0 <= c3 {
+			return Properties{}, 1
+		}
+		return Properties{entry: trie.lookupValue(uint32(i), c3)}, 4
+	}
+	// Illegal rune
+	return Properties{}, 1
+}
+
+// LookupString returns properties for the first rune in s and the width in
+// bytes of its encoding. The size will be 0 if s does not hold enough bytes to
+// complete the encoding.
+func LookupString(s string) (p Properties, sz int) {
+	c0 := s[0]
+	switch {
+	case c0 < 0x80: // is ASCII
+		return Properties{entry: bidiValues[c0]}, 1
+	case c0 < 0xC2:
+		return Properties{}, 1
+	case c0 < 0xE0: // 2-byte UTF-8
+		if len(s) < 2 {
+			return Properties{}, 0
+		}
+		i := bidiIndex[c0]
+		c1 := s[1]
+		if c1 < 0x80 || 0xC0 <= c1 {
+			return Properties{}, 1
+		}
+		return Properties{entry: trie.lookupValue(uint32(i), c1)}, 2
+	case c0 < 0xF0: // 3-byte UTF-8
+		if len(s) < 3 {
+			return Properties{}, 0
+		}
+		i := bidiIndex[c0]
+		c1 := s[1]
+		if c1 < 0x80 || 0xC0 <= c1 {
+			return Properties{}, 1
+		}
+		o := uint32(i)<<6 + uint32(c1)
+		i = bidiIndex[o]
+		c2 := s[2]
+		if c2 < 0x80 || 0xC0 <= c2 {
+			return Properties{}, 1
+		}
+		return Properties{entry: trie.lookupValue(uint32(i), c2), last: c2}, 3
+	case c0 < 0xF8: // 4-byte UTF-8
+		if len(s) < 4 {
+			return Properties{}, 0
+		}
+		i := bidiIndex[c0]
+		c1 := s[1]
+		if c1 < 0x80 || 0xC0 <= c1 {
+			return Properties{}, 1
+		}
+		o := uint32(i)<<6 + uint32(c1)
+		i = bidiIndex[o]
+		c2 := s[2]
+		if c2 < 0x80 || 0xC0 <= c2 {
+			return Properties{}, 1
+		}
+		o = uint32(i)<<6 + uint32(c2)
+		i = bidiIndex[o]
+		c3 := s[3]
+		if c3 < 0x80 || 0xC0 <= c3 {
+			return Properties{}, 1
+		}
+		return Properties{entry: trie.lookupValue(uint32(i), c3)}, 4
+	}
+	// Illegal rune
+	return Properties{}, 1
+}

vendor/golang.org/x/text/unicode/bidi/trieval.go

+// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
+
+package bidi
+
+// Class is the Unicode BiDi class. Each rune has a single class.
+type Class uint
+
+const (
+	L       Class = iota // LeftToRight
+	R                    // RightToLeft
+	EN                   // EuropeanNumber
+	ES                   // EuropeanSeparator
+	ET                   // EuropeanTerminator
+	AN                   // ArabicNumber
+	CS                   // CommonSeparator
+	B                    // ParagraphSeparator
+	S                    // SegmentSeparator
+	WS                   // WhiteSpace
+	ON                   // OtherNeutral
+	BN                   // BoundaryNeutral
+	NSM                  // NonspacingMark
+	AL                   // ArabicLetter
+	Control              // Control LRO - PDI
+
+	numClass
+
+	LRO // LeftToRightOverride
+	RLO // RightToLeftOverride
+	LRE // LeftToRightEmbedding
+	RLE // RightToLeftEmbedding
+	PDF // PopDirectionalFormat
+	LRI // LeftToRightIsolate
+	RLI // RightToLeftIsolate
+	FSI // FirstStrongIsolate
+	PDI // PopDirectionalIsolate
+
+	unknownClass = ^Class(0)
+)
+
+var controlToClass = map[rune]Class{
+	0x202D: LRO, // LeftToRightOverride,
+	0x202E: RLO, // RightToLeftOverride,
+	0x202A: LRE, // LeftToRightEmbedding,
+	0x202B: RLE, // RightToLeftEmbedding,
+	0x202C: PDF, // PopDirectionalFormat,
+	0x2066: LRI, // LeftToRightIsolate,
+	0x2067: RLI, // RightToLeftIsolate,
+	0x2068: FSI, // FirstStrongIsolate,
+	0x2069: PDI, // PopDirectionalIsolate,
+}
+
+// A trie entry has the following bits:
+// 7..5  XOR mask for brackets
+// 4     1: Bracket open, 0: Bracket close
+// 3..0  Class type
+
+const (
+	openMask     = 0x10
+	xorMaskShift = 5
+)

vendor/golang.org/x/text/unicode/norm/composition.go

+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package norm
+
+import "unicode/utf8"
+
+const (
+	maxNonStarters = 30
+	// The maximum number of characters needed for a buffer is
+	// maxNonStarters + 1 for the starter + 1 for the GCJ
+	maxBufferSize    = maxNonStarters + 2
+	maxNFCExpansion  = 3  // NFC(0x1D160)
+	maxNFKCExpansion = 18 // NFKC(0xFDFA)
+
+	maxByteBufferSize = utf8.UTFMax * maxBufferSize // 128
+)
+
+// ssState is used for reporting the segment state after inserting a rune.
+// It is returned by streamSafe.next.
+type ssState int
+
+const (
+	// Indicates a rune was successfully added to the segment.
+	ssSuccess ssState = iota
+	// Indicates a rune starts a new segment and should not be added.
+	ssStarter
+	// Indicates a rune caused a segment overflow and a CGJ should be inserted.
+	ssOverflow
+)
+
+// streamSafe implements the policy of when a CGJ should be inserted.
+type streamSafe uint8
+
+// first inserts the first rune of a segment. It is a faster version of next if
+// it is known p represents the first rune in a segment.
+func (ss *streamSafe) first(p Properties) {
+	*ss = streamSafe(p.nTrailingNonStarters())
+}
+
+// insert returns a ssState value to indicate whether a rune represented by p
+// can be inserted.
+func (ss *streamSafe) next(p Properties) ssState {
+	if *ss > maxNonStarters {
+		panic("streamSafe was not reset")
+	}
+	n := p.nLeadingNonStarters()
+	if *ss += streamSafe(n); *ss > maxNonStarters {
+		*ss = 0
+		return ssOverflow
+	}
+	// The Stream-Safe Text Processing prescribes that the counting can stop
+	// as soon as a starter is encountered. However, there are some starters,
+	// like Jamo V and T, that can combine with other runes, leaving their
+	// successive non-starters appended to the previous, possibly causing an
+	// overflow. We will therefore consider any rune with a non-zero nLead to
+	// be a non-starter. Note that it always hold that if nLead > 0 then
+	// nLead == nTrail.
+	if n == 0 {
+		*ss = streamSafe(p.nTrailingNonStarters())
+		return ssStarter
+	}
+	return ssSuccess
+}
+
+// backwards is used for checking for overflow and segment starts
+// when traversing a string backwards. Users do not need to call first
+// for the first rune. The state of the streamSafe retains the count of
+// the non-starters loaded.
+func (ss *streamSafe) backwards(p Properties) ssState {
+	if *ss > maxNonStarters {
+		panic("streamSafe was not reset")
+	}
+	c := *ss + streamSafe(p.nTrailingNonStarters())
+	if c > maxNonStarters {
+		return ssOverflow
+	}
+	*ss = c
+	if p.nLeadingNonStarters() == 0 {
+		return ssStarter
+	}
+	return ssSuccess
+}
+
+func (ss streamSafe) isMax() bool {
+	return ss == maxNonStarters
+}
+
+// GraphemeJoiner is inserted after maxNonStarters non-starter runes.
+const GraphemeJoiner = "\u034F"
+
+// reorderBuffer is used to normalize a single segment.  Characters inserted with
+// insert are decomposed and reordered based on CCC. The compose method can
+// be used to recombine characters.  Note that the byte buffer does not hold
+// the UTF-8 characters in order.  Only the rune array is maintained in sorted
+// order. flush writes the resulting segment to a byte array.
+type reorderBuffer struct {
+	rune  [maxBufferSize]Properties // Per character info.
+	byte  [maxByteBufferSize]byte   // UTF-8 buffer. Referenced by runeInfo.pos.
+	nbyte uint8                     // Number or bytes.
+	ss    streamSafe                // For limiting length of non-starter sequence.
+	nrune int                       // Number of runeInfos.
+	f     formInfo
+
+	src      input
+	nsrc     int
+	tmpBytes input
+
+	out    []byte
+	flushF func(*reorderBuffer) bool
+}
+
+func (rb *reorderBuffer) init(f Form, src []byte) {
+	rb.f = *formTable[f]
+	rb.src.setBytes(src)
+	rb.nsrc = len(src)
+	rb.ss = 0
+}
+
+func (rb *reorderBuffer) initString(f Form, src string) {
+	rb.f = *formTable[f]
+	rb.src.setString(src)
+	rb.nsrc = len(src)
+	rb.ss = 0
+}
+
+func (rb *reorderBuffer) setFlusher(out []byte, f func(*reorderBuffer) bool) {
+	rb.out = out
+	rb.flushF = f
+}
+
+// reset discards all characters from the buffer.
+func (rb *reorderBuffer) reset() {
+	rb.nrune = 0
+	rb.nbyte = 0
+}
+
+func (rb *reorderBuffer) doFlush() bool {
+	if rb.f.composing {
+		rb.compose()
+	}
+	res := rb.flushF(rb)
+	rb.reset()
+	return res
+}
+
+// appendFlush appends the normalized segment to rb.out.
+func appendFlush(rb *reorderBuffer) bool {
+	for i := 0; i < rb.nrune; i++ {
+		start := rb.rune[i].pos
+		end := start + rb.rune[i].size
+		rb.out = append(rb.out, rb.byte[start:end]...)
+	}
+	return true
+}
+
+// flush appends the normalized segment to out and resets rb.
+func (rb *reorderBuffer) flush(out []byte) []byte {
+	for i := 0; i < rb.nrune; i++ {
+		start := rb.rune[i].pos
+		end := start + rb.rune[i].size
+		out = append(out, rb.byte[start:end]...)
+	}
+	rb.reset()
+	return out
+}
+
+// flushCopy copies the normalized segment to buf and resets rb.
+// It returns the number of bytes written to buf.
+func (rb *reorderBuffer) flushCopy(buf []byte) int {
+	p := 0
+	for i := 0; i < rb.nrune; i++ {
+		runep := rb.rune[i]
+		p += copy(buf[p:], rb.byte[runep.pos:runep.pos+runep.size])
+	}
+	rb.reset()
+	return p
+}
+
+// insertOrdered inserts a rune in the buffer, ordered by Canonical Combining Class.
+// It returns false if the buffer is not large enough to hold the rune.
+// It is used internally by insert and insertString only.
+func (rb *reorderBuffer) insertOrdered(info Properties) {
+	n := rb.nrune
+	b := rb.rune[:]
+	cc := info.ccc
+	if cc > 0 {
+		// Find insertion position + move elements to make room.
+		for ; n > 0; n-- {
+			if b[n-1].ccc <= cc {
+				break
+			}
+			b[n] = b[n-1]
+		}
+	}
+	rb.nrune += 1
+	pos := uint8(rb.nbyte)
+	rb.nbyte += utf8.UTFMax
+	info.pos = pos
+	b[n] = info
+}
+
+// insertErr is an error code returned by insert. Using this type instead
+// of error improves performance up to 20% for many of the benchmarks.
+type insertErr int
+
+const (
+	iSuccess insertErr = -iota
+	iShortDst
+	iShortSrc
+)
+
+// insertFlush inserts the given rune in the buffer ordered by CCC.
+// If a decomposition with multiple segments are encountered, they leading
+// ones are flushed.
+// It returns a non-zero error code if the rune was not inserted.
+func (rb *reorderBuffer) insertFlush(src input, i int, info Properties) insertErr {
+	if rune := src.hangul(i); rune != 0 {
+		rb.decomposeHangul(rune)
+		return iSuccess
+	}
+	if info.hasDecomposition() {
+		return rb.insertDecomposed(info.Decomposition())
+	}
+	rb.insertSingle(src, i, info)
+	return iSuccess
+}
+
+// insertUnsafe inserts the given rune in the buffer ordered by CCC.
+// It is assumed there is sufficient space to hold the runes. It is the
+// responsibility of the caller to ensure this. This can be done by checking
+// the state returned by the streamSafe type.
+func (rb *reorderBuffer) insertUnsafe(src input, i int, info Properties) {
+	if rune := src.hangul(i); rune != 0 {
+		rb.decomposeHangul(rune)
+	}
+	if info.hasDecomposition() {
+		// TODO: inline.
+		rb.insertDecomposed(info.Decomposition())
+	} else {
+		rb.insertSingle(src, i, info)
+	}
+}
+
+// insertDecomposed inserts an entry in to the reorderBuffer for each rune
+// in dcomp. dcomp must be a sequence of decomposed UTF-8-encoded runes.
+// It flushes the buffer on each new segment start.
+func (rb *reorderBuffer) insertDecomposed(dcomp []byte) insertErr {
+	rb.tmpBytes.setBytes(dcomp)
+	// As the streamSafe accounting already handles the counting for modifiers,
+	// we don't have to call next. However, we do need to keep the accounting
+	// intact when flushing the buffer.
+	for i := 0; i < len(dcomp); {
+		info := rb.f.info(rb.tmpBytes, i)
+		if info.BoundaryBefore() && rb.nrune > 0 && !rb.doFlush() {
+			return iShortDst
+		}
+		i += copy(rb.byte[rb.nbyte:], dcomp[i:i+int(info.size)])
+		rb.insertOrdered(info)
+	}
+	return iSuccess
+}
+
+// insertSingle inserts an entry in the reorderBuffer for the rune at
+// position i. info is the runeInfo for the rune at position i.
+func (rb *reorderBuffer) insertSingle(src input, i int, info Properties) {
+	src.copySlice(rb.byte[rb.nbyte:], i, i+int(info.size))
+	rb.insertOrdered(info)
+}
+
+// insertCGJ inserts a Combining Grapheme Joiner (0x034f) into rb.
+func (rb *reorderBuffer) insertCGJ() {
+	rb.insertSingle(input{str: GraphemeJoiner}, 0, Properties{size: uint8(len(GraphemeJoiner))})
+}
+
+// appendRune inserts a rune at the end of the buffer. It is used for Hangul.
+func (rb *reorderBuffer) appendRune(r rune) {
+	bn := rb.nbyte
+	sz := utf8.EncodeRune(rb.byte[bn:], rune(r))
+	rb.nbyte += utf8.UTFMax
+	rb.rune[rb.nrune] = Properties{pos: bn, size: uint8(sz)}
+	rb.nrune++
+}
+
+// assignRune sets a rune at position pos. It is used for Hangul and recomposition.
+func (rb *reorderBuffer) assignRune(pos int, r rune) {
+	bn := rb.rune[pos].pos
+	sz := utf8.EncodeRune(rb.byte[bn:], rune(r))
+	rb.rune[pos] = Properties{pos: bn, size: uint8(sz)}
+}
+
+// runeAt returns the rune at position n. It is used for Hangul and recomposition.
+func (rb *reorderBuffer) runeAt(n int) rune {
+	inf := rb.rune[n]
+	r, _ := utf8.DecodeRune(rb.byte[inf.pos : inf.pos+inf.size])
+	return r
+}
+
+// bytesAt returns the UTF-8 encoding of the rune at position n.
+// It is used for Hangul and recomposition.
+func (rb *reorderBuffer) bytesAt(n int) []byte {
+	inf := rb.rune[n]
+	return rb.byte[inf.pos : int(inf.pos)+int(inf.size)]
+}
+
+// For Hangul we combine algorithmically, instead of using tables.
+const (
+	hangulBase  = 0xAC00 // UTF-8(hangulBase) -> EA B0 80
+	hangulBase0 = 0xEA
+	hangulBase1 = 0xB0
+	hangulBase2 = 0x80
+
+	hangulEnd  = hangulBase + jamoLVTCount // UTF-8(0xD7A4) -> ED 9E A4
+	hangulEnd0 = 0xED
+	hangulEnd1 = 0x9E
+	hangulEnd2 = 0xA4
+
+	jamoLBase  = 0x1100 // UTF-8(jamoLBase) -> E1 84 00
+	jamoLBase0 = 0xE1
+	jamoLBase1 = 0x84
+	jamoLEnd   = 0x1113
+	jamoVBase  = 0x1161
+	jamoVEnd   = 0x1176
+	jamoTBase  = 0x11A7
+	jamoTEnd   = 0x11C3
+
+	jamoTCount   = 28
+	jamoVCount   = 21
+	jamoVTCount  = 21 * 28
+	jamoLVTCount = 19 * 21 * 28
+)
+
+const hangulUTF8Size = 3
+
+func isHangul(b []byte) bool {
+	if len(b) < hangulUTF8Size {
+		return false
+	}
+	b0 := b[0]
+	if b0 < hangulBase0 {
+		return false
+	}
+	b1 := b[1]
+	switch {
+	case b0 == hangulBase0:
+		return b1 >= hangulBase1
+	case b0 < hangulEnd0:
+		return true
+	case b0 > hangulEnd0:
+		return false
+	case b1 < hangulEnd1:
+		return true
+	}
+	return b1 == hangulEnd1 && b[2] < hangulEnd2
+}
+
+func isHangulString(b string) bool {
+	if len(b) < hangulUTF8Size {
+		return false
+	}
+	b0 := b[0]
+	if b0 < hangulBase0 {
+		return false
+	}
+	b1 := b[1]
+	switch {
+	case b0 == hangulBase0:
+		return b1 >= hangulBase1
+	case b0 < hangulEnd0:
+		return true
+	case b0 > hangulEnd0:
+		return false
+	case b1 < hangulEnd1:
+		return true
+	}
+	return b1 == hangulEnd1 && b[2] < hangulEnd2
+}
+
+// Caller must ensure len(b) >= 2.
+func isJamoVT(b []byte) bool {
+	// True if (rune & 0xff00) == jamoLBase
+	return b[0] == jamoLBase0 && (b[1]&0xFC) == jamoLBase1
+}
+
+func isHangulWithoutJamoT(b []byte) bool {
+	c, _ := utf8.DecodeRune(b)
+	c -= hangulBase
+	return c < jamoLVTCount && c%jamoTCount == 0
+}
+
+// decomposeHangul writes the decomposed Hangul to buf and returns the number
+// of bytes written.  len(buf) should be at least 9.
+func decomposeHangul(buf []byte, r rune) int {
+	const JamoUTF8Len = 3
+	r -= hangulBase
+	x := r % jamoTCount
+	r /= jamoTCount
+	utf8.EncodeRune(buf, jamoLBase+r/jamoVCount)
+	utf8.EncodeRune(buf[JamoUTF8Len:], jamoVBase+r%jamoVCount)
+	if x != 0 {
+		utf8.EncodeRune(buf[2*JamoUTF8Len:], jamoTBase+x)
+		return 3 * JamoUTF8Len
+	}
+	return 2 * JamoUTF8Len
+}
+
+// decomposeHangul algorithmically decomposes a Hangul rune into
+// its Jamo components.
+// See http://unicode.org/reports/tr15/#Hangul for details on decomposing Hangul.
+func (rb *reorderBuffer) decomposeHangul(r rune) {
+	r -= hangulBase
+	x := r % jamoTCount
+	r /= jamoTCount
+	rb.appendRune(jamoLBase + r/jamoVCount)
+	rb.appendRune(jamoVBase + r%jamoVCount)
+	if x != 0 {
+		rb.appendRune(jamoTBase + x)
+	}
+}
+
+// combineHangul algorithmically combines Jamo character components into Hangul.
+// See http://unicode.org/reports/tr15/#Hangul for details on combining Hangul.
+func (rb *reorderBuffer) combineHangul(s, i, k int) {
+	b := rb.rune[:]
+	bn := rb.nrune
+	for ; i < bn; i++ {
+		cccB := b[k-1].ccc
+		cccC := b[i].ccc
+		if cccB == 0 {
+			s = k - 1
+		}
+		if s != k-1 && cccB >= cccC {
+			// b[i] is blocked by greater-equal cccX below it
+			b[k] = b[i]
+			k++
+		} else {
+			l := rb.runeAt(s) // also used to compare to hangulBase
+			v := rb.runeAt(i) // also used to compare to jamoT
+			switch {
+			case jamoLBase <= l && l < jamoLEnd &&
+				jamoVBase <= v && v < jamoVEnd:
+				// 11xx plus 116x to LV
+				rb.assignRune(s, hangulBase+
+					(l-jamoLBase)*jamoVTCount+(v-jamoVBase)*jamoTCount)
+			case hangulBase <= l && l < hangulEnd &&
+				jamoTBase < v && v < jamoTEnd &&
+				((l-hangulBase)%jamoTCount) == 0:
+				// ACxx plus 11Ax to LVT
+				rb.assignRune(s, l+v-jamoTBase)
+			default:
+				b[k] = b[i]
+				k++
+			}
+		}
+	}
+	rb.nrune = k
+}
+
+// compose recombines the runes in the buffer.
+// It should only be used to recompose a single segment, as it will not
+// handle alternations between Hangul and non-Hangul characters correctly.
+func (rb *reorderBuffer) compose() {
+	// UAX #15, section X5 , including Corrigendum #5
+	// "In any character sequence beginning with starter S, a character C is
+	//  blocked from S if and only if there is some character B between S
+	//  and C, and either B is a starter or it has the same or higher
+	//  combining class as C."
+	bn := rb.nrune
+	if bn == 0 {
+		return
+	}
+	k := 1
+	b := rb.rune[:]
+	for s, i := 0, 1; i < bn; i++ {
+		if isJamoVT(rb.bytesAt(i)) {
+			// Redo from start in Hangul mode. Necessary to support
+			// U+320E..U+321E in NFKC mode.
+			rb.combineHangul(s, i, k)
+			return
+		}
+		ii := b[i]
+		// We can only use combineForward as a filter if we later
+		// get the info for the combined character. This is more
+		// expensive than using the filter. Using combinesBackward()
+		// is safe.
+		if ii.combinesBackward() {
+			cccB := b[k-1].ccc
+			cccC := ii.ccc
+			blocked := false // b[i] blocked by starter or greater or equal CCC?
+			if cccB == 0 {
+				s = k - 1
+			} else {
+				blocked = s != k-1 && cccB >= cccC
+			}
+			if !blocked {
+				combined := combine(rb.runeAt(s), rb.runeAt(i))
+				if combined != 0 {
+					rb.assignRune(s, combined)
+					continue
+				}
+			}
+		}
+		b[k] = b[i]
+		k++
+	}
+	rb.nrune = k
+}

vendor/golang.org/x/text/unicode/norm/transform.go

+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package norm
+
+import (
+	"unicode/utf8"
+
+	"golang.org/x/text/transform"
+)
+
+// Reset implements the Reset method of the transform.Transformer interface.
+func (Form) Reset() {}
+
+// Transform implements the Transform method of the transform.Transformer
+// interface. It may need to write segments of up to MaxSegmentSize at once.
+// Users should either catch ErrShortDst and allow dst to grow or have dst be at
+// least of size MaxTransformChunkSize to be guaranteed of progress.
+func (f Form) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+	n := 0
+	// Cap the maximum number of src bytes to check.
+	b := src
+	eof := atEOF
+	if ns := len(dst); ns < len(b) {
+		err = transform.ErrShortDst
+		eof = false
+		b = b[:ns]
+	}
+	i, ok := formTable[f].quickSpan(inputBytes(b), n, len(b), eof)
+	n += copy(dst[n:], b[n:i])
+	if !ok {
+		nDst, nSrc, err = f.transform(dst[n:], src[n:], atEOF)
+		return nDst + n, nSrc + n, err
+	}
+	if n < len(src) && !atEOF {
+		err = transform.ErrShortSrc
+	}
+	return n, n, err
+}
+
+func flushTransform(rb *reorderBuffer) bool {
+	// Write out (must fully fit in dst, or else it is an ErrShortDst).
+	if len(rb.out) < rb.nrune*utf8.UTFMax {
+		return false
+	}
+	rb.out = rb.out[rb.flushCopy(rb.out):]
+	return true
+}
+
+var errs = []error{nil, transform.ErrShortDst, transform.ErrShortSrc}
+
+// transform implements the transform.Transformer interface. It is only called
+// when quickSpan does not pass for a given string.
+func (f Form) transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+	// TODO: get rid of reorderBuffer. See CL 23460044.
+	rb := reorderBuffer{}
+	rb.init(f, src)
+	for {
+		// Load segment into reorder buffer.
+		rb.setFlusher(dst[nDst:], flushTransform)
+		end := decomposeSegment(&rb, nSrc, atEOF)
+		if end < 0 {
+			return nDst, nSrc, errs[-end]
+		}
+		nDst = len(dst) - len(rb.out)
+		nSrc = end
+
+		// Next quickSpan.
+		end = rb.nsrc
+		eof := atEOF
+		if n := nSrc + len(dst) - nDst; n < end {
+			err = transform.ErrShortDst
+			end = n
+			eof = false
+		}
+		end, ok := rb.f.quickSpan(rb.src, nSrc, end, eof)
+		n := copy(dst[nDst:], rb.src.bytes[nSrc:end])
+		nSrc += n
+		nDst += n
+		if ok {
+			if n < rb.nsrc && !atEOF {
+				err = transform.ErrShortSrc
+			}
+			return nDst, nSrc, err
+		}
+	}
+}