xend_internal.c

/*
 * xend_internal.c: access to Xen though the Xen Daemon interface
 *
 * Copyright (C) 2005
 *
 *      Anthony Liguori <aliguori@us.ibm.com>
 *
 *  This file is subject to the terms and conditions of the GNU Lesser General
 *  Public License. See the file COPYING.LIB in the main directory of this
 *  archive for more details.
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/errno.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#include <math.h>
#include <stdarg.h>
#include <malloc.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <netdb.h>

#include "sexpr.h"
#include "xend_internal.h"

/**
 * xend_connection_type:
 *
 * The connection to the Xen Daemon can be done either though a normal TCP
 * socket or a local domain direct connection.
 */
enum xend_connection_type {
    XEND_DOMAIN,
    XEND_TCP,
};

/**
 * xend:
 *
 * Structure associated to a connection to a Xen daemon
 */
struct xend {
    int len;
    int type;
    struct sockaddr *addr;
    struct sockaddr_un addr_un;
    struct sockaddr_in addr_in;
};

#define foreach(iterator, start) \
       	for (_for_i = (start), *iterator = (start)->car; \
             _for_i->kind == SEXPR_CONS; \
             _for_i = _for_i->cdr, iterator = _for_i->car)

#define foreach_node(iterator, start, path) \
        foreach(iterator, start) \
            if (sexpr_lookup(iterator, path))

/**
 * do_connect:
 * @xend: pointer to the Xen Daemon structure
 *
 * Internal routine to (re)connect to the daemon
 *
 * Returns the socket file descriptor or -1 in case of error
 */
static int
do_connect(struct xend *xend)
{
    int s;
    int serrno;

    s = socket(xend->type, SOCK_STREAM, 0);
    if (s == -1)
        return -1;

    if (connect(s, xend->addr, xend->len) == -1) {
        serrno = errno;
        close(s);
        errno = serrno;
        s = -1;
    }

    return s;
}

/**
 * wr_sync:
 * @fd:  the file descriptor
 * @buffer: the I/O buffer
 * @size: the size of the I/O
 * @do_read: write operation if 0, read operation otherwise
 *
 * Do a synchronous read or write on the file descriptor
 *
 * Returns the number of bytes exchanged, or -1 in case of error
 */
static size_t
wr_sync(int fd, void *buffer, size_t size, int do_read)
{
    size_t offset = 0;

    while (offset < size) {
        ssize_t len;

        if (do_read) {
            len = read(fd, ((char *)buffer) + offset, size - offset);
        } else {
            len = write(fd, ((char *)buffer) + offset, size - offset);
        }

        /* recoverable error, retry  */
        if ((len == -1) && ((errno == EAGAIN) || (errno == EINTR))) {
            continue;
        }

        /* eof */
        if (len == 0) {
            break;
        }

        /* unrecoverable error */
        if (len == -1) {
            return(-1);
        }

        offset += len;
    }

    return offset;
}

/**
 * sread:
 * @fd:  the file descriptor
 * @buffer: the I/O buffer
 * @size: the size of the I/O
 *
 * Internal routine to do a synchronous read
 *
 * Returns the number of bytes read, or -1 in case of error
 */
static ssize_t
sread(int fd, void *buffer, size_t size)
{
    return wr_sync(fd, buffer, size, 1);
}

/**
 * swrite:
 * @fd:  the file descriptor
 * @buffer: the I/O buffer
 * @size: the size of the I/O
 *
 * Internal routine to do a synchronous write
 *
 * Returns the number of bytes written, or -1 in case of error
 */
static ssize_t
swrite(int fd, const void *buffer, size_t size)
{
    return wr_sync(fd, (void *) buffer, size, 0);
}

/**
 * swrites:
 * @fd:  the file descriptor
 * @string: the string to write
 *
 * Internal routine to do a synchronous write of a string
 *
 * Returns the number of bytes written, or -1 in case of error
 */
static ssize_t
swrites(int fd, const char *string)
{
    return swrite(fd, string, strlen(string));
}

/**
 * sreads:
 * @fd:  the file descriptor
 * @buffer: the I/O buffer
 * @n_buffer: the size of the I/O buffer
 *
 * Internal routine to do a synchronous read of a line
 *
 * Returns the number of bytes read, or -1 in case of error
 */
static ssize_t
sreads(int fd, char *buffer, size_t n_buffer)
{
    size_t offset;

    if (n_buffer < 1)
        return(-1);

    for (offset = 0; offset < (n_buffer - 1); offset++) {
        ssize_t ret;

        ret = sread(fd, buffer + offset, 1);
        if (ret == 0)
            break;
        else if (ret == -1)
            return ret;

        if (buffer[offset] == '\n') {
            offset++;
            break;
        }
    }
    buffer[offset] = 0;

    return offset;
}

static int
istartswith(const char *haystack, const char *needle)
{
    return (strncasecmp(haystack, needle, strlen(needle)) == 0);
}

/**
 * xend_req:
 * @fd: the file descriptor
 * @content: the buffer to store the content
 * @n_content: the size of the buffer
 *
 * Read the HTTP response from a Xen Daemon request.
 *
 * Returns the HTTP return code.
 */
static int
xend_req(int fd, char *content, size_t n_content)
{
    char buffer[4096];
    int content_length = -1;
    int retcode = 0;


    while (sreads(fd, buffer, sizeof(buffer)) > 0) {
        if (strcmp(buffer, "\r\n") == 0)
            break;

        if (istartswith(buffer, "Content-Length: "))
            content_length = atoi(buffer + 16);
        else if (istartswith(buffer, "HTTP/1.1 "))
            retcode = atoi(buffer + 9);
    }

    if (content_length > -1) {
        ssize_t ret;

        if ((unsigned int) content_length > (n_content + 1))
            content_length = n_content - 1;

        ret = sread(fd, content, content_length);
        if (ret < 0)
            return -1;

        content[ret] = 0;
    } else {
        content[0] = 0;
    }

    return retcode;
}

/**
 * xend_get:
 * @xend: pointer to the Xen Daemon structure
 * @path: the path used for the HTTP request
 * @content: the buffer to store the content
 * @n_content: the size of the buffer
 *
 * Do an HTTP GET RPC with the Xen Daemon
 *
 * Returns the HTTP return code or -1 in case or error.
 */
static int
xend_get(struct xend *xend, const char *path,
         char *content, size_t n_content)
{
    int ret;
    int s = do_connect(xend);

    if (s == -1)
        return s;

    swrites(s, "GET ");
    swrites(s, path);
    swrites(s, " HTTP/1.1\r\n");

    swrites(s,
            "Host: localhost:8000\r\n"
            "Accept-Encoding: identity\r\n"
            "Content-Type: application/x-www-form-urlencoded\r\n" "\r\n");

    ret = xend_req(s, content, n_content);
    close(s);

    return ret;
}

/**
 * xend_post:
 * @xend: pointer to the Xen Daemon structure
 * @path: the path used for the HTTP request
 * @ops: the informations sent for the POST
 * @content: the buffer to store the content
 * @n_content: the size of the buffer
 *
 * Do an HTTP POST RPC with the Xen Daemon, this usually makes changes at the
 * Xen level.
 *
 * Returns the HTTP return code or -1 in case or error.
 */
static int
xend_post(struct xend *xend, const char *path, const char *ops,
          char *content, size_t n_content)
{
    char buffer[100];
    int ret;
    int s = do_connect(xend);

    if (s == -1)
        return s;

    swrites(s, "POST ");
    swrites(s, path);
    swrites(s, " HTTP/1.1\r\n");

    swrites(s,
            "Host: localhost:8000\r\n"
            "Accept-Encoding: identity\r\n"
            "Content-Type: application/x-www-form-urlencoded\r\n"
            "Content-Length: ");
    snprintf(buffer, sizeof(buffer), "%d", strlen(ops));
    swrites(s, buffer);
    swrites(s, "\r\n\r\n");
    swrites(s, ops);

    ret = xend_req(s, content, n_content);
    close(s);

    return ret;
}

/**
 * http2unix:
 * @ret: the http return code
 *
 * Convert the HTTP return code to 0/-1 and set errno if needed
 *
 * Return -1 in case of error code 0 otherwise
 */
static int
http2unix(int ret)
{
    switch (ret) {
        case -1:
            break;
        case 200:
        case 201:
        case 202:
            return 0;
        case 404:
            errno = ESRCH;
            break;
        default:
            printf("unknown error code %d\n", ret);
            errno = EINVAL;
            break;
    }
    return -1;
}

/**
 * xend_op_ext2:
 * @xend: pointer to the Xen Daemon structure
 * @path: path for the object
 * @error: buffer for the error output
 * @n_error: size of @error
 * @key: the key for the operation
 * @ap: input values to pass to the operation
 *
 * internal routine to run a POST RPC operation to the Xen Daemon
 *
 * Returns 0 in case of success, -1 in case of failure.
 */
static int
xend_op_ext2(struct xend *xend, const char *path, char *error,
             size_t n_error, const char *key, va_list ap)
{
    char ops[1024];
    const char *k = key, *v;
    int offset = 0;

    while (k) {
        v = va_arg(ap, const char *);

        offset += snprintf(ops + offset, sizeof(ops) - offset, "%s", k);
        offset += snprintf(ops + offset, sizeof(ops) - offset, "%s", "=");
        offset += snprintf(ops + offset, sizeof(ops) - offset, "%s", v);
        k = va_arg(ap, const char *);

        if (k)
            offset += snprintf(ops + offset,
                               sizeof(ops) - offset, "%s", "&");
    }

    return http2unix(xend_post(xend, path, ops, error, n_error));
}

/**
 * xend_node_op:
 * @xend: pointer to the Xen Daemon structure
 * @path: path for the object
 * @key: the key for the operation
 * @...: input values to pass to the operation
 *
 * internal routine to run a POST RPC operation to the Xen Daemon
 *
 * Returns 0 in case of success, -1 in case of failure.
 */
static int
xend_node_op(struct xend *xend, const char *path, const char *key, ...)
{
    va_list ap;
    int ret;
    char error[1024];

    va_start(ap, key);
    ret = xend_op_ext2(xend, path, error, sizeof(error), key, ap);
    va_end(ap);

    return ret;
}

/**
 * xend_node_op:
 * @xend: pointer to the Xen Daemon structure
 * @name: the domain name target of this operation
 * @error: buffer for the error output
 * @n_error: size of @error
 * @key: the key for the operation
 * @ap: input values to pass to the operation
 * @...: input values to pass to the operation
 *
 * internal routine to run a POST RPC operation to the Xen Daemon targetting
 * a given domain.
 *
 * Returns 0 in case of success, -1 in case of failure.
 */
static int
xend_op_ext(struct xend *xend, const char *name, char *error,
            size_t n_error, const char *key, ...)
{
    char buffer[1024];
    va_list ap;
    int ret;

    snprintf(buffer, sizeof(buffer), "/xend/domain/%s", name);

    va_start(ap, key);
    ret = xend_op_ext2(xend, buffer, error, n_error, key, ap);
    va_end(ap);

    return ret;
}

#define xend_op(xend, name, key, ...) ({char error[1024]; xend_op_ext(xend, name, error, sizeof(error), key, __VA_ARGS__);})

/**
 * sexpr_get:
 * @xend: pointer to the Xen Daemon structure
 * @fmt: format string for the path of the operation
 * @...: extra data to build the path of the operation
 *
 * Internal routine to run a simple GET RPC operation to the Xen Daemon
 *
 * Returns a parsed S-Expression in case of success, NULL in case of failure
 */
static struct sexpr *
sexpr_get(struct xend *xend, const char *fmt, ...)
{
    char buffer[4096];
    char path[1024];
    va_list ap;
    int ret;

    va_start(ap, fmt);
    vsnprintf(path, sizeof(path), fmt, ap);
    va_end(ap);

    ret = xend_get(xend, path, buffer, sizeof(buffer));
    ret = http2unix(ret);
    if (ret == -1)
        return NULL;

    return string2sexpr(buffer);
}

/**
 * sexpr_append_str:
 * @sexpr: an S-Expression
 * @name: the name of the property
 * @value: the string value
 *
 * convenience function appending a (name value) property to the S-Expression
 *
 * Returns the augmented S-Expression
 */
static struct sexpr *
sexpr_append_str(struct sexpr *sexpr, const char *name, const char *value)
{
    struct sexpr *lst;

    if (!value)
        return sexpr;

    lst = sexpr_append(sexpr_nil(), sexpr_string(name, -1));
    lst = sexpr_append(lst, sexpr_string(value, -1));
    return sexpr_append(sexpr, lst);
}

/**
 * sexpr_append_u64:
 * @sexpr: an S-Expression
 * @name: the name of the property
 * @value: a 64 bits unsigned int value
 *
 * convenience function appending a (name value) property to the S-Expression
 *
 * Returns the augmented S-Expression
 */
static struct sexpr *
sexpr_append_u64(struct sexpr *sexpr, const char *name, uint64_t value)
{
    char buffer[1024];

    snprintf(buffer, sizeof(buffer), "%llu", value);
    return sexpr_append_str(sexpr, name, buffer);
}

/**
 * sexpr_append_int:
 * @sexpr: an S-Expression
 * @name: the name of the property
 * @value: an int value
 *
 * convenience function appending a (name value) property to the S-Expression
 *
 * Returns the augmented S-Expression
 */
static struct sexpr *
sexpr_append_int(struct sexpr *sexpr, const char *name, int value)
{
    char buffer[1024];

    snprintf(buffer, sizeof(buffer), "%d", value);
    return sexpr_append_str(sexpr, name, buffer);
}

/**
 * sexpr_append_uuid:
 * @sexpr: an S-Expression
 * @name: the name of the property
 * @uuid: an unique identifier for a domain
 *
 * convenience function appending a (name uuid) property to the S-Expression
 *
 * Returns the augmented S-Expression
 */
static struct sexpr *
sexpr_append_uuid(struct sexpr *sexpr,
                  const char *name, unsigned char *uuid)
{
    char buffer[1024];

    if (uuid == NULL)
        return sexpr;

    snprintf(buffer, sizeof(buffer),
             "%02x%02x%02x%02x-"
             "%02x%02x%02x%02x-"
             "%02x%02x%02x%02x-"
             "%02x%02x%02x%02x",
             uuid[0], uuid[1], uuid[2], uuid[3],
             uuid[4], uuid[5], uuid[6], uuid[7],
             uuid[8], uuid[9], uuid[10], uuid[11],
             uuid[12], uuid[13], uuid[14], uuid[15]);

    return sexpr_append_str(sexpr, name, buffer);
}

/**
 * sexpr_int:
 * @sexpr: an S-Expression
 * @name: the name for the value
 *
 * convenience function to lookup an int value in the S-Expression
 *
 * Returns the value found or 0 if not found (but may not be an error)
 */
static int
sexpr_int(struct sexpr *sexpr, const char *name)
{
    const char *value = sexpr_node(sexpr, name);

    if (value) {
        return strtol(value, NULL, 0);
    }
    return 0;
}

/**
 * sexpr_float:
 * @sexpr: an S-Expression
 * @name: the name for the value
 *
 * convenience function to lookup a float value in the S-Expression
 *
 * Returns the value found or 0 if not found (but may not be an error)
 */
static double
sexpr_float(struct sexpr *sexpr, const char *name)
{
    const char *value = sexpr_node(sexpr, name);

    if (value) {
        return strtod(value, NULL);
    }
    return 0;
}

/**
 * sexpr_u64:
 * @sexpr: an S-Expression
 * @name: the name for the value
 *
 * convenience function to lookup a 64bits unsigned int value in the
 * S-Expression
 *
 * Returns the value found or 0 if not found (but may not be an error)
 */
static uint64_t
sexpr_u64(struct sexpr *sexpr, const char *name)
{
    const char *value = sexpr_node(sexpr, name);

    if (value) {
        return strtoll(value, NULL, 0);
    }
    return 0;
}

/**
 * sexpr_u64:
 * @sexpr: an S-Expression
 * @name: the name for the value
 *
 * convenience function to lookup a value describing the default process when
 * a domain stops
 *
 * Returns the value found or 0 if not found (but may not be an error)
 */
static enum xend_domain_restart
sexpr_poweroff(struct sexpr *sexpr, const char *name)
{
    const char *value = sexpr_node(sexpr, name);

    if (value) {
        if (strcmp(value, "poweroff") == 0) {
            return XEND_DESTROY;
        } else if (strcmp(value, "restart") == 0) {
            return XEND_RESTART;
        } else if (strcmp(value, "preserve") == 0) {
            return XEND_PRESERVE;
        } else if (strcmp(value, "rename-restart") == 0) {
            return XEND_RENAME_RESTART;
        }
    }
    return XEND_DEFAULT;
}

static int
sexpr_strlen(struct sexpr *sexpr, const char *path)
{
    const char *r = sexpr_node(sexpr, path);

    return r ? (strlen(r) + 1) : 0;
}

static const char *
sexpr_strcpy(char **ptr, struct sexpr *node, const char *path)
{
    const char *ret = sexpr_node(node, path);

    if (ret) {
        strcpy(*ptr, ret);
        ret = *ptr;
        *ptr += (strlen(ret) + 1);
    }
    return ret;
}

/**
 * sexpr_mode:
 * @sexpr: an S-Expression
 * @name: the name for the value
 *
 * convenience function to lookup a value describing a virtual block device
 * mode from the S-Expression
 *
 * Returns the value found or 0 if not found (but may not be an error)
 */
static enum xend_device_vbd_mode
sexpr_mode(struct sexpr *node, const char *path)
{
    const char *mode = sexpr_node(node, path);
    enum xend_device_vbd_mode ret;

    if (!mode) {
        ret = XEND_DEFAULT;
    } else if (strcmp(mode, "r") == 0) {
        ret = XEND_READ_ONLY;
    } else if (strcmp(mode, "w") == 0) {
        ret = XEND_READ_WRITE;
    } else if (strcmp(mode, "w!") == 0) {
        ret = XEND_READ_WRITE_FORCE;
    } else {
        ret = XEND_DEFAULT;
    }

    return ret;
}

/**
 * sexpr_node_system:
 * @sexpr: an S-Expression
 * @name: the name for the value
 *
 * convenience function to lookup a value describing the kind of system
 * from the S-Expression
 *
 * Returns the value found or 0 if not found (but may not be an error)
 */
static enum xend_node_system
sexpr_node_system(struct sexpr *node, const char *path)
{
    const char *syst = sexpr_node(node, path);

    if (syst) {
        if (strcmp(syst, "Linux") == 0) {
            return XEND_SYSTEM_LINUX;
        }
    }

    return XEND_DEFAULT;
}

/**
 * sexpr_node_system:
 * @mac: return value for the MAC address
 * @sexpr: an S-Expression
 * @name: the name for the value
 *
 * convenience function to lookup a MAC address (assumed ethernet and hence
 * six bytes in length) from the S-Expression
 * The value is returned in @mac
 */
static void
sexpr_mac(uint8_t * mac, struct sexpr *node, const char *path)
{
    const char *r = sexpr_node(node, path);
    int mmac[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
    if (r) {
        int i;

        sscanf(r, "%02x:%02x:%02x:%02x:%02x:%02x",
               mmac + 0, mmac + 1, mmac + 2, mmac + 3, mmac + 4, mmac + 5);
        for (i = 0; i < 6; i++)
            mac[i] = mmac[i] & 0xFF;
    }
}

/**
 * sexpr_uuid:
 * @ptr: where to store the UUID, incremented
 * @sexpr: an S-Expression
 * @name: the name for the value
 *
 * convenience function to lookup an UUID value from the S-Expression
 *
 * Returns a pointer to the stored UUID or NULL in case of error.
 */
static unsigned char *
sexpr_uuid(char **ptr, struct sexpr *node, const char *path)
{
    const char *r = sexpr_node(node, path);
    int uuid[16];
    unsigned char *dst_uuid = NULL;
    int ret;
    int i;

    memset(uuid, 0xFF, sizeof(uuid));

    if (r == NULL)
        goto error;

    ret = sscanf(r,
                 "%02x%02x%02x%02x-"
                 "%02x%02x-"
                 "%02x%02x-"
                 "%02x%02x-"
                 "%02x%02x%02x%02x%02x%02x",
                 uuid + 0, uuid + 1, uuid + 2, uuid + 3,
                 uuid + 4, uuid + 5, uuid + 6, uuid + 7,
                 uuid + 8, uuid + 9, uuid + 10, uuid + 11,
                 uuid + 12, uuid + 13, uuid + 14, uuid + 15);
    if (ret == 16)
        goto done;

    ret = sscanf(r,
                 "%02x%02x%02x%02x-"
                 "%02x%02x%02x%02x-"
                 "%02x%02x%02x%02x-"
                 "%02x%02x%02x%02x",
                 uuid + 0, uuid + 1, uuid + 2, uuid + 3,
                 uuid + 4, uuid + 5, uuid + 6, uuid + 7,
                 uuid + 8, uuid + 9, uuid + 10, uuid + 11,
                 uuid + 12, uuid + 13, uuid + 14, uuid + 15);
    if (ret != 16)
        goto error;

  done:
    dst_uuid = (unsigned char *) *ptr;
    *ptr += 16;

    for (i = 0; i < 16; i++)
        dst_uuid[i] = uuid[i] & 0xFF;

  error:
    return dst_uuid;
}


/**
 * urlencode:
 * @string: the input URL
 *
 * Encode an URL see RFC 2396 and following
 *
 * Returns the new string or NULL in case of error.
 */
static char *
urlencode(const char *string)
{
    size_t len = strlen(string);
    char *buffer = malloc(len * 3 + 1);
    char *ptr = buffer;
    size_t i;

    if (buffer == NULL)
        return(NULL);
    for (i = 0; i < len; i++) {
        switch (string[i]) {
            case ' ':
            case '\n':
                sprintf(ptr, "%%%02x", string[i]);
                ptr += 3;
                break;
            default:
                *ptr = string[i];
                ptr++;
        }
    }

    *ptr = 0;

    return buffer;
}

/**
 * xend_device_vbd_to_sexpr:
 * @vbd: a virtual block device pointer
 *
 * Encode a virtual block device as an S-Expression understood by the
 * Xen Daemon
 *
 * Returns the result S-Expression pointer
 */
static struct sexpr *
xend_device_vbd_to_sexpr(const struct xend_device_vbd *vbd)
{
    struct sexpr *device = sexpr_nil();
    const char *mode[] = { NULL, "r", "w", "w!" };

    sexpr_append(device, sexpr_string("vbd", -1));
    sexpr_append_str(device, "dev", vbd->dev);
    sexpr_append_str(device, "uname", vbd->uname);
    sexpr_append_int(device, "backend", vbd->backend);
    sexpr_append_str(device, "mode", mode[vbd->mode]);

    return device;
}

/**
 * xend_device_vif_to_sexpr:
 * @vif: a virtual network interface pointer
 *
 * Encode a virtual network interface as an S-Expression understood by the
 * Xen Daemon
 *
 * Returns the result S-Expression pointer
 */
static struct sexpr *
xend_device_vif_to_sexpr(const struct xend_device_vif *vif)
{
    struct sexpr *device;
    char buffer[1024];

    device = sexpr_append(sexpr_nil(), sexpr_string("vif", -1));

    snprintf(buffer, sizeof(buffer),
             "%02x:%02x:%02x:%02x:%02x:%02x",
             vif->mac[0], vif->mac[1], vif->mac[2],
             vif->mac[3], vif->mac[4], vif->mac[5]);
    device = sexpr_append_str(device, "mac", buffer);
    device = sexpr_append_int(device, "backend", vif->backend);
    device = sexpr_append_str(device, "bridge", vif->bridge);
    device = sexpr_append_str(device, "ip", vif->ip);
    device = sexpr_append_str(device, "script", vif->script);
    device = sexpr_append_str(device, "vifname", vif->vifname);

    return device;
}

/* PUBLIC FUNCTIONS */

/**
 * xend_new_unix:
 * @path: the path for the Xen Daemon socket
 *
 * Creates a localhost Xen Daemon connection
 * Note: this doesn't try to check if the connection actually works
 *
 * Returns the new pointer or NULL in case of error.
 */
struct xend *
xend_new_unix(const char *path)
{
    struct xend *xend = malloc(sizeof(*xend));
    struct sockaddr_un *addr;

    if (!xend)
        return NULL;

    addr = &xend->addr_un;
    addr->sun_family = AF_UNIX;
    memset(addr->sun_path, 0, sizeof(addr->sun_path));
    strncpy(addr->sun_path, path, sizeof(addr->sun_path));

    xend->len = sizeof(addr->sun_family) + strlen(addr->sun_path);
    if ((unsigned int) xend->len > sizeof(addr->sun_path))
        xend->len = sizeof(addr->sun_path);

    xend->addr = (struct sockaddr *) addr;
    xend->type = PF_UNIX;

    return xend;
}

/**
 * xend_new_unix:
 * @host: the host name for the Xen Daemon
 * @port: the port 
 *
 * Creates a possibly remote Xen Daemon connection
 * Note: this doesn't try to check if the connection actually works
 *
 * Returns the new pointer or NULL in case of error.
 */
struct xend *
xend_new_tcp(const char *host, int port)
{
    struct xend *xend = malloc(sizeof(*xend));
    struct in_addr ip;
    struct hostent *pent;

    if (!xend)
        return NULL;

    pent = gethostbyname(host);
    if (pent == NULL) {
        if (inet_aton(host, &ip) == 0) {
            errno = ESRCH;
            return NULL;
        }
    } else {
        memcpy(&ip, pent->h_addr_list[0], sizeof(ip));
    }

    xend->len = sizeof(struct sockaddr_in);
    xend->addr = (struct sockaddr *) &xend->addr_in;
    xend->type = PF_INET;

    xend->addr_in.sin_family = AF_INET;
    xend->addr_in.sin_port = htons(port);
    memcpy(&xend->addr_in.sin_addr, &ip, sizeof(ip));

    return xend;
}

/**
 * xend_new:
 *
 * Creates a localhost Xen Daemon connection
 * Note: this doesn't try to check if the connection actually works
 *
 * Returns the new pointer or NULL in case of error.
 */
struct xend *
xend_new(void)
{
    return xend_new_unix("/var/lib/xend/xend-socket");
}

/**
 * xend_delete:
 *
 * Free a Xen Daemon connection
 */
void
xend_delete(struct xend *xend)
{
    free(xend);
}

/**
 * xend_wait_for_devices:
 * @xend: pointer to the Xem Daemon block
 * @name: name for the domain
 *
 * Block the domain until all the virtual devices are ready. This operation
 * is needed when creating a domain before resuming it.
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_wait_for_devices(struct xend *xend, const char *name)
{
    return xend_op(xend, name, "op", "wait_for_devices", NULL);
}

/**
 * xend_pause:
 * @xend: pointer to the Xem Daemon block
 * @name: name for the domain
 *
 * Pause the domain, the domain is not scheduled anymore though its resources
 * are preserved. Use xend_unpause() to resume execution.
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_pause(struct xend *xend, const char *name)
{
    return xend_op(xend, name, "op", "pause", NULL);
}

/**
 * xend_unpause:
 * @xend: pointer to the Xem Daemon block
 * @name: name for the domain
 *
 * Resume the domain after xend_pause() has been called
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_unpause(struct xend *xend, const char *name)
{
    return xend_op(xend, name, "op", "unpause", NULL);
}

/**
 * xend_rename:
 * @xend: pointer to the Xem Daemon block
 * @old: old name for the domain
 * @new: new name for the domain
 *
 * Rename the domain
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_rename(struct xend *xend, const char *old, const char *new)
{
    if ((xend == NULL) || (old == NULL) || (new == NULL))
        return(-1);
    return xend_op(xend, old, "op", "rename", "name", new, NULL);
}

/**
 * xend_reboot:
 * @xend: pointer to the Xem Daemon block
 * @name: name for the domain
 *
 * Reboot the domain, the OS is properly shutdown and restarted
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_reboot(struct xend *xend, const char *name)
{
    if ((xend == NULL) || (name == NULL))
        return(-1);
    return xend_op(xend, name, "op", "shutdown", "reason", "reboot", NULL);
}

/**
 * xend_shutdown:
 * @xend: pointer to the Xem Daemon block
 * @name: name for the domain
 *
 * Shutdown the domain, the OS is properly shutdown and the resources allocated
 * for the domain are freed.
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_shutdown(struct xend *xend, const char *name)
{
    if ((xend == NULL) || (name == NULL))
        return(-1);
    return xend_op(xend, name,
                   "op", "shutdown", "reason", "shutdown", NULL);
}

/**
 * xend_sysrq:
 * @xend: pointer to the Xem Daemon block
 * @name: name for the domain
 * @key: the SysReq key
 *
 * Send a SysReq key which is used to debug Linux kernels running in the domain
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_sysrq(struct xend *xend, const char *name, const char *key)
{
    if ((xend == NULL) || (name == NULL) || (key == NULL))
        return(-1);
    return xend_op(xend, name, "op", "sysrq", "key", key, NULL);
}

/**
 * xend_destroy:
 * @xend: pointer to the Xem Daemon block
 * @name: name for the domain
 *
 * Abruptly halt the domain, the OS is not properly shutdown and the
 * resources allocated for the domain are immediately freed, mounted
 * filesystems will be marked as uncleanly shutdown.
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_destroy(struct xend *xend, const char *name)
{
    if ((xend == NULL) || (name == NULL))
        return(-1);
    return xend_op(xend, name, "op", "destroy", NULL);
}

/**
 * xend_save:
 * @xend: pointer to the Xem Daemon block
 * @name: name for the domain
 * @filename: path for the output file
 *
 * This method will suspend a domain and save its memory contents to
 * a file on disk.  Use xend_restore() to restore a domain after
 * saving.
 * Note that for remote Xen Daemon the file path will be interpreted in
 * the remote host.
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_save(struct xend *xend, const char *name, const char *filename)
{
    if ((xend == NULL) || (filename == NULL))
        return(-1);
    return xend_op(xend, name, "op", "save", "file", filename, NULL);
}

/**
 * xend_restore:
 * @xend: pointer to the Xem Daemon block
 * @filename: path for the output file
 *
 * This method will restore a domain saved to disk by xend_save().
 * Note that for remote Xen Daemon the file path will be interpreted in
 * the remote host.
 *
 * Returns 0 in case of success, -1 (with errno) in case of error.
 */
int
xend_restore(struct xend *xend, const char *filename)
{
    if ((xend == NULL) || (filename == NULL))
        return(-1);
    return xend_op(xend, "", "op", "restore", "file", filename, NULL);
}

/**
 * xend_get_domains:
 * @xend: pointer to the Xem Daemon block
 *
 * This method will return an array of names of currently running
 * domains.  The memory should be released will a call to free().
 *
 * Returns a list of names or NULL in case of error.
 */
char **
xend_get_domains(struct xend *xend)
{
    size_t extra = 0;
    struct sexpr *root = NULL;
    char **ret = NULL;
    int count = 0;
    int i;
    char *ptr;
    struct sexpr *_for_i, *node;

    root = sexpr_get(xend, "/xend/domain");
    if (root == NULL)
        goto error;

    for (_for_i = root, node = root->car; _for_i->kind == SEXPR_CONS;
         _for_i = _for_i->cdr, node = _for_i->car) {
        if (node->kind != SEXPR_VALUE)
            continue;
        extra += strlen(node->value) + 1;
        count++;
    }

    ptr = malloc((count + 1) * sizeof(char *) + extra);
    if (ptr == NULL)
        goto error;

    ret = (char **) ptr;
    ptr += sizeof(char *) * (count + 1);

    i = 0;
    for (_for_i = root, node = root->car; _for_i->kind == SEXPR_CONS;
         _for_i = _for_i->cdr, node = _for_i->car) {
        if (node->kind != SEXPR_VALUE)
            continue;
        ret[i] = ptr;
        strcpy(ptr, node->value);
        ptr += strlen(node->value) + 1;
        i++;
    }

    ret[i] = NULL;

  error:
    sexpr_free(root);
    return ret;
}

/**
 * xend_domain_to_sexpr:
 * @domain: a domain pointer 
 *
 * Internal function converting the domain informations into an S-Expression
 * that the Xen Daemon can use to create instances
 *
 * Returns the new S-Expression or NULL in case of error.
 */
static struct sexpr *
xend_domain_to_sexpr(const struct xend_domain *domain)
{
    struct sexpr *lst = sexpr_nil();
    struct sexpr *image = sexpr_nil();
    struct sexpr *builder = sexpr_nil();
    const char *restart[] = { NULL, "restart",
        "preserve", "rename-restart"
    };
    size_t i;

    if (domain == NULL)
        return(NULL);

    lst = sexpr_append(lst, sexpr_string("vm", -1));
    lst = sexpr_append_str(lst, "name", domain->name);
    lst = sexpr_append_uuid(lst, "uuid", domain->uuid);
    lst = sexpr_append_u64(lst, "memory", domain->memory);
    lst = sexpr_append_int(lst, "ssidref", domain->ssidref);
    lst = sexpr_append_u64(lst, "maxmem", domain->max_memory);
    lst =
        sexpr_append_str(lst, "on_poweroff", restart[domain->on_poweroff]);
    lst = sexpr_append_str(lst, "on_reboot", restart[domain->on_reboot]);
    lst = sexpr_append_str(lst, "on_crash", restart[domain->on_crash]);
    lst = sexpr_append_int(lst, "vcpus", domain->vcpus);

    builder = sexpr_append(builder, sexpr_string("linux", -1));
    builder = sexpr_append_str(builder, "kernel", domain->image.kernel);
    builder = sexpr_append_str(builder, "ramdisk", domain->image.ramdisk);
    builder = sexpr_append_str(builder, "root", domain->image.root);
    builder = sexpr_append_str(builder, "args", domain->image.extra);

    image = sexpr_append(image, sexpr_string("image", -1));
    image = sexpr_append(image, builder);

    lst = sexpr_append(lst, image);

    for (i = 0; i < domain->n_vbds; i++) {
        struct sexpr *device = sexpr_nil();
        struct sexpr *vbd = xend_device_vbd_to_sexpr(&domain->vbds[i]);

        device = sexpr_append(device, sexpr_string("device", -1));
        device = sexpr_append(device, vbd);
        lst = sexpr_append(lst, device);
    }

    for (i = 0; i < domain->n_vifs; i++) {
        struct sexpr *device = sexpr_nil();
        struct sexpr *vif = xend_device_vif_to_sexpr(&domain->vifs[i]);

        device = sexpr_append(device, sexpr_string("device", -1));
        device = sexpr_append(device, vif);
        lst = sexpr_append(lst, device);
    }

    for (i = 0; i < domain->n_ioports; i++) {
        struct sexpr *device = sexpr_nil();
        struct sexpr *ioport = sexpr_nil();

        ioport = sexpr_append(ioport, sexpr_string("ioports", -1));
        ioport = sexpr_append_int(ioport, "from", domain->ioports[i].from);
        ioport = sexpr_append_int(ioport, "to", domain->ioports[i].to);

        device = sexpr_append(device, sexpr_string("device", -1));
        device = sexpr_append(device, ioport);
        lst = sexpr_append(lst, device);
    }

    return lst;
}

/**
 * xend_create:
 * @xend: A xend instance
 * @info: A struct xen_domain instance describing the domain
 *
 * This method will create a domain based the passed in description.  The
 * domain will be paused after creation and must be unpaused with
 * xend_unpause() to begin execution.
 *
 * Returns 0 for success, -1 (with errno) on error
 */

int
xend_create(struct xend *xend, const struct xend_domain *dom)
{
    int ret, serrno;
    struct sexpr *sexpr;
    char buffer[4096];
    char *ptr;

    sexpr = xend_domain_to_sexpr(dom);
    sexpr2string(sexpr, buffer, sizeof(buffer));
    ptr = urlencode(buffer);

    ret = xend_op(xend, "", "op", "create", "config", ptr, NULL);

    serrno = errno;
    free(ptr);
    sexpr_free(sexpr);
    errno = serrno;

    return ret;
}

/**
 * xend_set_max_memory:
 * @xend: A xend instance
 * @name: The name of the domain
 * @value: The maximum memory in bytes
 *
 * This method will set the maximum amount of memory that can be allocated to
 * a domain.  Please note that a domain is able to allocate up to this amount
 * on its own (although under normal circumstances, memory allocation for a
 * domain is only done through xend_set_memory()).
 *
 * Returns 0 for success; -1 (with errno) on error
 */
int
xend_set_max_memory(struct xend *xend, const char *name, uint64_t value)
{
    char buf[1024];

    snprintf(buf, sizeof(buf), "%llu", value >> 20);
    return xend_op(xend, name, "op", "maxmem_set", "memory", buf, NULL);
}

/**
 * xend_set_memory:
 * @xend: A xend instance
 * @name: The name of the domain
 * @value: The desired allocation in bytes
 *
 * This method will set a target memory allocation for a given domain and
 * request that the guest meet this target.  The guest may or may not actually
 * achieve this target.  When this function returns, it does not signify that
 * the domain has actually reached that target.
 *
 * Memory for a domain can only be allocated up to the maximum memory setting.
 * There is no safe guard for allocations that are too small so be careful
 * when using this function to reduce a domain's memory usage.
 *
 * Returns 0 for success; -1 (with errno) on error
 */
int
xend_set_memory(struct xend *xend, const char *name, uint64_t value)
{
    char buf[1024];

    snprintf(buf, sizeof(buf), "%llu", value >> 20);
    return xend_op(xend, name, "op", "mem_target_set", "target", buf,
                   NULL);
}

/**
 * xend_vbd_create:
 * @xend: A xend instance
 * @name: The name of the domain
 * @vbd: A virtual block device description
 *
 * This method creates and attachs a block device to a domain.  A successful
 * return value does not indicate that the device successfully attached,
 * rather, one should use xend_wait_for_devices() to block until the device
 * has been successfully attached.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_vbd_create(struct xend *xend,
                const char *name, const struct xend_device_vbd *vbd)
{
    char buffer[4096];
    char *ptr;
    int ret;
    struct sexpr *device;

    device = xend_device_vbd_to_sexpr(vbd);

    sexpr2string(device, buffer, sizeof(buffer));
    ptr = urlencode(buffer);

    ret = xend_op(xend, name, "op", "device_create", "config", ptr, NULL);

    sexpr_free(device);

    return ret;
}

/**
 * xend_vbd_destroy:
 * @xend: A xend instance
 * @name: The name of the domain
 * @vbd: A virtual block device description
 *
 * This method detachs a block device from a given domain.  A successful return
 * value does not indicate that the device successfully detached, rather, one
 * should use xend_wait_for_devices() to block until the device has been
 * successfully detached.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_vbd_destroy(struct xend *xend,
                 const char *name, const struct xend_device_vbd *vbd)
{
    return xend_op(xend, name, "op", "device_destroy", "type", "vbd",
                   "dev", vbd->dev, NULL);
}

/**
 * xend_vif_create:
 * @xend: A xend instance
 * @name: The name of the domain
 * @vif: A virtual network device description
 *
 * This method creates and attachs a network device to a domain.  A successful
 * return value does not indicate that the device successfully attached,
 * rather, one should use xend_wait_for_devices() to network until the device
 * has been successfully attached.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_vif_create(struct xend *xend,
                const char *name, const struct xend_device_vif *vif)
{
    char buffer[4096];
    char *ptr;
    int ret;
    struct sexpr *device;

    device = xend_device_vif_to_sexpr(vif);

    sexpr2string(device, buffer, sizeof(buffer));
    ptr = urlencode(buffer);

    ret = xend_op(xend, name, "op", "device_create", "config", ptr, NULL);

    sexpr_free(device);

    return ret;
}

static int
get_vif_handle(struct xend *xend,
               const char *name,
               const struct xend_device_vif *vif,
               char *buffer, size_t n_buffer)
{
    struct sexpr *root;
    char path[4096];
    int ret = -1;
    struct sexpr *_for_i, *node;

    root = sexpr_get(xend, "/xend/domain");
    if (root == NULL)
        goto error;

    errno = ESRCH;

    for (_for_i = root, node = root->car; _for_i->kind == SEXPR_CONS;
         _for_i = _for_i->cdr, node = _for_i->car) {
        uint8_t mac[6];

        if (node->car->kind != SEXPR_VALUE)
            continue;

        snprintf(path, sizeof(path), "%s/mac", node->car->value);
        sexpr_mac(mac, node, path);
        if (memcmp(mac, vif->mac, 6) == 0) {
            snprintf(buffer, n_buffer, "%s", node->car->value);
            ret = 0;
            break;
        }
    }

  error:
    sexpr_free(root);
    return ret;

}

/**
 * xend_vif_destroy:
 * @xend: A xend instance
 * @name: The name of the domain
 * @vif: A virtual network device description
 *
 * This method detachs a network device from a given domain.  A successful
 * return value does not indicate that the device successfully detached,
 * rather, one should use xend_wait_for_devices() to network until the device
 * has been successfully detached.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_vif_destroy(struct xend *xend,
                 const char *name, const struct xend_device_vif *vif)
{
    char handle[1024];

    if (get_vif_handle(xend, name, vif, handle, sizeof(handle)) == -1)
        return -1;

    return xend_op(xend, name, "op", "device_destroy", "type", "vif",
                   "dev", handle, NULL);
}

/**
 * sexpr_to_xend_domain_size:
 * @sexpr: the S-Expression
 * @n_vbds: the number of virtual block devices used (OUT)
 * @n_vifs: the number of network interface devices used (OUT)
 *
 * Helper function to compute the size in byte needed for the strings
 * of a domain.
 *
 * Returns the number of bytes and the output parameters
 */
static size_t
sexpr_to_xend_domain_size(struct sexpr *root, int *n_vbds, int *n_vifs)
{
    size_t size = 0;
    struct sexpr *_for_i, *node;

    size += sexpr_strlen(root, "domain/name");
    size += sexpr_strlen(root, "domain/image/linux/kernel");
    size += sexpr_strlen(root, "domain/image/linux/ramdisk");
    size += sexpr_strlen(root, "domain/image/linux/root");
    size += sexpr_strlen(root, "domain/image/linux/args");
    if (sexpr_node(root, "domain/uuid"))
        size += 16;

    for (_for_i = root, node = root->car; _for_i->kind == SEXPR_CONS;
         _for_i = _for_i->cdr, node = _for_i->car) {
	if (sexpr_lookup(node, "device/vbd")) {
	    size += sexpr_strlen(node, "device/vbd/dev");
	    size += sexpr_strlen(node, "device/vbd/uname");
	    (*n_vbds)++;
	}
    }

    for (_for_i = root, node = root->car; _for_i->kind == SEXPR_CONS;
         _for_i = _for_i->cdr, node = _for_i->car) {
	if (sexpr_lookup(node, "device/vif")) {
	    size += sexpr_strlen(node, "device/vif/bridge");
	    size += sexpr_strlen(node, "device/vif/ip");
	    size += sexpr_strlen(node, "device/vif/script");
	    size += sexpr_strlen(node, "device/vif/vifname");
	    (*n_vifs)++;
        }
    }

    size += (*n_vbds) * sizeof(struct xend_device_vbd *);
    size += (*n_vbds) * sizeof(struct xend_device_vbd);

    size += (*n_vifs) * sizeof(struct xend_device_vif *);
    size += (*n_vifs) * sizeof(struct xend_device_vif);

    size += sizeof(struct xend_domain_live);

    size += sizeof(struct xend_domain);

    return size;
}

/**
 * sexpr_to_xend_domain:
 * @root: an S-Expression describing a domain
 *
 * Internal routine creating a domain node based on the S-Expression
 * provided by the Xen Daemon
 *
 * Returns a new structure or NULL in case of error.
 */
static struct xend_domain *
sexpr_to_xend_domain(struct sexpr *root)
{
    struct xend_domain *dom = NULL;
    char *ptr;
    int i;
    int n_vbds = 0;
    int n_vifs = 0;
    struct sexpr *_for_i, *node;

    ptr = malloc(sexpr_to_xend_domain_size(root, &n_vbds, &n_vifs));
    if (ptr == NULL)
        goto error;

    dom = (struct xend_domain *) ptr;
    ptr += sizeof(struct xend_domain);

    dom->vbds = (struct xend_device_vbd *) ptr;
    dom->n_vbds = n_vbds;
    ptr += n_vbds * sizeof(struct xend_device_vbd);

    dom->vifs = (struct xend_device_vif *) ptr;
    dom->n_vifs = n_vifs;
    ptr += n_vifs * sizeof(struct xend_device_vif);

    dom->live = (struct xend_domain_live *) ptr;
    ptr += sizeof(struct xend_domain_live);

    dom->name = sexpr_strcpy(&ptr, root, "domain/name");
    dom->uuid = sexpr_uuid(&ptr, root, "domain/uuid");
    dom->image.kernel =
        sexpr_strcpy(&ptr, root, "domain/image/linux/kernel");
    dom->image.ramdisk =
        sexpr_strcpy(&ptr, root, "domain/image/linux/ramdisk");
    dom->image.root = sexpr_strcpy(&ptr, root, "domain/image/linux/root");
    dom->image.extra = sexpr_strcpy(&ptr, root, "domain/image/linux/args");
    dom->memory = sexpr_u64(root, "domain/memory") << 20;
    dom->max_memory = sexpr_u64(root, "domain/maxmem") << 20;
    dom->ssidref = sexpr_int(root, "domain/ssidref");
    dom->on_poweroff = sexpr_poweroff(root, "domain/on_poweroff");
    dom->on_reboot = sexpr_poweroff(root, "domain/on_reboot");
    dom->on_crash = sexpr_poweroff(root, "domain/on_crash");
    dom->vcpus = sexpr_int(root, "domain/vcpus");

    {
        const char *flags = sexpr_node(root, "domain/state");

        if (flags) {
            dom->live->running = strchr(flags, 'r');
            dom->live->crashed = strchr(flags, 'c');
            dom->live->blocked = strchr(flags, 'b');
            dom->live->dying = strchr(flags, 'd');
            dom->live->paused = strchr(flags, 'p');
            dom->live->poweroff = false;
            dom->live->reboot = false;
            dom->live->suspend = false;
            if (strchr(flags, 's') &&
                (flags = sexpr_node(root, "domain/shutdown_reason"))) {
                if (strcmp(flags, "poweroff") == 0) {
                    dom->live->poweroff = true;
                } else if (strcmp(flags, "reboot") == 0) {
                    dom->live->reboot = true;
                } else if (strcmp(flags, "suspend") == 0) {
                    dom->live->suspend = true;
                }
            }
        }
    }

    dom->live->cpu_time = sexpr_float(root, "domain/cpu_time");
    dom->live->up_time = sexpr_float(root, "domain/up_time");
    dom->live->start_time = sexpr_float(root, "domain/start_time");
    dom->live->online_vcpus = sexpr_int(root, "domain/online_vcpus");
    dom->live->vcpu_avail = sexpr_int(root, "domain/vcpu_avail");

    i = 0;
    for (_for_i = root, node = root->car; _for_i->kind == SEXPR_CONS;
         _for_i = _for_i->cdr, node = _for_i->car) {
	if (sexpr_lookup(node, "device/vbd")) {
	    dom->vbds[i].dev = sexpr_strcpy(&ptr, node, "device/vbd/dev");
	    dom->vbds[i].uname = sexpr_strcpy(&ptr, node, "device/vbd/uname");
	    dom->vbds[i].backend = sexpr_int(node, "device/vbd/backend");
	    dom->vbds[i].mode = sexpr_mode(node, "device/vbd/mode");
	    i++;
	}
    }

    i = 0;
    for (_for_i = root, node = root->car; _for_i->kind == SEXPR_CONS;
         _for_i = _for_i->cdr, node = _for_i->car) {
	if (sexpr_lookup(node, "device/vif")) {
	    dom->vifs[i].backend = sexpr_int(node, "device/vif/backend");
	    dom->vifs[i].bridge =
		sexpr_strcpy(&ptr, node, "device/vif/bridge");
	    dom->vifs[i].ip = sexpr_strcpy(&ptr, node, "device/vif/ip");
	    sexpr_mac(dom->vifs[i].mac, node, "device/vif/mac");
	    dom->vifs[i].script =
		sexpr_strcpy(&ptr, node, "device/vif/script");
	    dom->vifs[i].vifname =
		sexpr_strcpy(&ptr, node, "device/vif/vifname");
	    i++;
        }
    }

error:
    return dom;
}

/**
 * xend_get_domain:
 * @xend: A xend instance
 * @name: The name of the domain
 *
 * This method looks up information about a domain and returns
 * it in the form of a struct xend_domain.  This should be
 * free()'d when no longer needed.
 *
 * Returns domain info on success; NULL (with errno) on error
 */
struct xend_domain *
xend_get_domain(struct xend *xend, const char *domname)
{
    struct sexpr *root;
    struct xend_domain *dom = NULL;

    root = sexpr_get(xend, "/xend/domain/%s?detail=1", domname);
    if (root == NULL)
        goto error;

    dom = sexpr_to_xend_domain(root);

  error:
    sexpr_free(root);
    return dom;
}

/**
 * xend_get_node:
 * @xend: A xend instance
 *
 * This method returns information about the physical host
 * machine running Xen.
 *
 * Returns node info on success; NULL (with errno) on error
 */
struct xend_node *
xend_get_node(struct xend *xend)
{
    struct sexpr *root;
    struct xend_node *node = NULL;
    size_t size;
    char *ptr;

    root = sexpr_get(xend, "/xend/node/");
    if (root == NULL)
        goto error;

    size = sizeof(struct xend_node);
    size += sexpr_strlen(root, "node/host");
    size += sexpr_strlen(root, "node/release");
    size += sexpr_strlen(root, "node/version");
    size += sexpr_strlen(root, "node/machine");
    size += sexpr_strlen(root, "node/hw_caps");
    size += sexpr_strlen(root, "node/xen_caps");
    size += sexpr_strlen(root, "node/platform_params");
    size += sexpr_strlen(root, "node/xen_changeset");
    size += sexpr_strlen(root, "node/cc_compiler");
    size += sexpr_strlen(root, "node/cc_compile_by");
    size += sexpr_strlen(root, "node/cc_compile_domain");
    size += sexpr_strlen(root, "node/cc_compile_date");

    ptr = malloc(size);
    if (ptr == NULL)
        goto error;

    node = (struct xend_node *) ptr;
    ptr += sizeof(struct xend_node);

    node->system = sexpr_node_system(root, "node/system");
    node->host = sexpr_strcpy(&ptr, root, "node/host");
    node->release = sexpr_strcpy(&ptr, root, "node/release");
    node->version = sexpr_strcpy(&ptr, root, "node/version");
    node->machine = sexpr_strcpy(&ptr, root, "node/machine");
    node->nr_cpus = sexpr_int(root, "node/nr_cpus");
    node->nr_nodes = sexpr_int(root, "node/nr_nodes");
    node->sockets_per_node = sexpr_int(root, "node/sockets_per_node");
    node->cores_per_socket = sexpr_int(root, "node/cores_per_socket");
    node->threads_per_core = sexpr_int(root, "node/threads_per_core");
    node->cpu_mhz = sexpr_int(root, "node/cpu_mhz");
    node->hw_caps = sexpr_strcpy(&ptr, root, "node/hw_caps");
    node->total_memory = sexpr_u64(root, "node/total_memory") << 12;
    node->free_memory = sexpr_u64(root, "node/free_memory") << 12;
    node->xen_major = sexpr_int(root, "node/xen_major");
    node->xen_minor = sexpr_int(root, "node/xen_minor");
    {
        const char *tmp;

        tmp = sexpr_node(root, "node/xen_extra");
        if (tmp) {
            if (*tmp == '.')
                tmp++;
            node->xen_extra = atoi(tmp);
        } else {
            node->xen_extra = 0;
        }
    }
    node->xen_caps = sexpr_strcpy(&ptr, root, "node/xen_caps");
    node->platform_params =
        sexpr_strcpy(&ptr, root, "node/platform_params");
    node->xen_changeset = sexpr_strcpy(&ptr, root, "node/xen_changeset");
    node->cc_compiler = sexpr_strcpy(&ptr, root, "node/cc_compiler");
    node->cc_compile_by = sexpr_strcpy(&ptr, root, "node/cc_compile_by");
    node->cc_compile_domain =
        sexpr_strcpy(&ptr, root, "node/cc_compile_domain");
    node->cc_compile_date =
        sexpr_strcpy(&ptr, root, "node/cc_compile_date");

  error:
    sexpr_free(root);
    return node;
}

/**
 * xend_node_shutdown:
 * @xend: A xend instance
 *
 * This method shuts down the physical machine running Xen.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_node_shutdown(struct xend *xend)
{
    return xend_node_op(xend, "/xend/node/", "op", "shutdown", NULL);
}

/**
 * xend_node_restart:
 * @xend: A xend instance
 *
 * This method restarts the physical machine running Xen.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_node_restart(struct xend *xend)
{
    return xend_node_op(xend, "/xend/node/", "op", "restart", NULL);
}

/**
 * xend_dmesg:
 * @xend: A xend instance
 * @buffer: A buffer to hold the messages
 * @n_buffer: Size of buffer (including null terminator)
 *
 * This function will place the debugging messages from the
 * hypervisor into a buffer with a null terminator.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_dmesg(struct xend *xend, char *buffer, size_t n_buffer)
{
    return http2unix(xend_get(xend, "/xend/node/dmesg", buffer, n_buffer));
}

/**
 * xend_dmesg_clear:
 * @xend: A xend instance
 *
 * This function will clear the debugging message ring queue
 * in the hypervisor.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_dmesg_clear(struct xend *xend)
{
    return xend_node_op(xend, "/xend/node/dmesg", "op", "clear", NULL);
}

/**
 * xend_log:
 * @xend: A xend instance
 * @buffer: The buffer to hold the messages
 * @n_buffer: Size of buffer (including null terminator)
 *
 * This function will place the Xend debugging messages into
 * a buffer with a null terminator.
 *
 * Returns 0 on success; -1 (with errno) on error
 */
int
xend_log(struct xend *xend, char *buffer, size_t n_buffer)
{
    return http2unix(xend_get(xend, "/xend/node/log", buffer, n_buffer));
}