* Add certificate bundle capability to WiFiClientSecure

Enable usage of the ESP32 IDF's certificate bundle for WiFiClientSecure connections.

Adds the ability to load a bundle or root certificates and use them for authenticating SSL servers.

Based on work from Onno-Dirkzwager, Duckle29, kubo6472, meltdown03, kinafu and others.

See also:
- https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/protocols/esp_crt_bundle.html
- https://github.com/espressif/arduino-esp32/issues/3646
- libraries/WiFiClientSecure/README.md

* Fix build issues

* Clean up old bundle index when NULL bundle is attached

This adds a function to WiFiClientSecure to set the ALPN protocol.

This is required for an MQTT client to connect to AWS IoT when using an AWS Custom Authorizer, as described here.

Example code snippet:

...
WiFiClientSecure wiFiClient;

// ALPN protocol, needed with AWS custom authorizer
const char *aws_protos[] = {"mqtt", NULL};

void setup() {
  wiFiClient.setCACert(AWSCAPEM);
  wiFiClient.setAlpnProtocols(aws_protos);
}
...

Add the ability to get the peer certificate of an SSL connection; useful for IoT when the root/cert trust chain has a shorter lifecylce than the device itself. Includes example

Closes #5398

Using the same non-blocking socket connect pattern for respecting connection timeout, copied from WiFiClient::connect.

WiFiClient::connect uses lwip_connect_r, whereas start_ssl_client uses lwip_connect. I haven't found what is the difference between them. I tested both, both work ok, so I kept lwip_connect.

Fixes: https://github.com/espressif/arduino-esp32/issues/4960

mbedTLS requires repeated calls to mbedtls_ssl_write() whenever it returns MBEDTLS_ERR_SSL_WANT_READ or MBEDTLS_ERR_SSL_WANT_WRITE. this happens when the client sends data faster then the server or the connection can handle.

Replace (depricated) bzero with memset.

Fixes: #3460

This code has been run in production for 1 month and it looks stable, no data dropped and it definitely fixes the issue described. I think that this can be merged to avoid using custom package referencing in PlatformIO that has been used in quite a few projects for now.
Co-authored-by: NIvan Golubic <ivan@mvt-solutions.com>

* Add an aditional (void *) arg to the RMT callback - to allow more flexible handling of the callback (e.g. by passing a private struct or a class pointer). Same pattern as used by the Ticker() and many others. Example updated & new example with a trapoline added.

* Fix example for new API

* Fix lint warnings

* Add a second missed example.

* Correct timeout & improve socket error handling.

I met problem while I was working with the WiFiClientSecure.
I tried to found the source of the problem, and I found it in the sll_client.cpp.
Please check my contribution.

I've open this problem in #4335 but received no response.

Especially if the user wants to use the library as component in IDF,
there are some pitfalls while doing make menuconfig. One is this missing
dependency which will now fail with a better error message with a hint to
the user how to fix it.

refs #2154 #3215

* Shows only free internal heap on logs

Since Mbedtls is running only on internal heap, show internal + PSRAM available memory on logs can confuse the users

* Clarify logs

* WiFiClientSecure: add support for PSK (pre-shared key) ciphers

* add example for WiFiClientSecure PSK

* WiFiClientSecure: added README

* issue #2041

* handshake timeout

* seconds to milliseconds

* fix sdmmc config

* Fix warnings in EEPROM

from @Curclamas

* remove leftover TAG in EEPROM

* Initial add of @stickbreaker i2c

* Add log_n

* fix warnings when log is off

* i2c code clean up and reorganization

* add flags to interrupt allocator

* fix sdmmc config

* Fix warnings in EEPROM

from @Curclamas

* remove leftover TAG in EEPROM

* fix errors with latest IDF

* fix debug optimization (#1365)

incorrect optimization for debugging tick markers.

* Fix some missing BT header

* Change BTSerial log calls

* Update BLE lib

* Arduino-ESP32 release management scripted (#1515)

* Calculate an absolute path for a custom partitions table (#1452)

* * Arduino-ESP32 release management scripted
(ready-to-merge)

* * secure env for espressif/arduino-esp32

* * build tests enabled
* gitter webhook enabled

* * gitter room link fixed
* better comment

* * filepaths fixed

* BT Serial adjustments

* * don't run sketch builds & tests for tagged builds

* Return false from WiFi.hostByName() if hostname is not resolved

* Free BT Memory when BT is not used

* WIFI_MODE_NULL is not supported anymore

* Select some key examples to build with PlatformIO to save some time

* Update BLE lib

* Fixed BLE lib

* Major WiFi overhaul

- auto reconnect on connection loss now works
- moved to event groups
- some code clean up and procedure optimizations
- new methods to get a more elaborate system ststus

* Add cmake tests to travis

* Add initial AsyncUDP

* Add NetBIOS lib and fix CMake includes

* Add Initial WebServer

* Fix WebServer and examples

* travis not quiting on build fail

* Try different travis build

* Update IDF to aaf1239

* Fix WPS Example

* fix script permission and add some fail tests to sketch builder

* Add missing space in WiFiClient::write(Stream &stream)

If you develop on windows and need cr/lf files, see this:

    https://git-scm.com/book/en/v2/Customizing-Git-Git-Configuration#_formatting_and_whitespace

    Git can handle this by auto-converting CRLF line endings into LF
    when you add a file to the index, and vice versa when it checks out
    code onto your filesystem. You can turn on this functionality with
    the core.autocrlf setting. If you're on a Windows machine, set it
    to true - this converts LF endings into CRLF when you check out code:

    $ git config --global core.autocrlf true

This reduce net_would_block calls and CPU utilization

Server Name Indication (SNI) support for WiFiClientSecure

Fix https://github.com/espressif/arduino-esp32/issues/571 and https://github.com/espressif/arduino-esp32/issues/550

* Remove duplicated include

* Clear certificates just after handshake

It can save up to 7k of heap

* Fix possible infinite loop in the example

* Remove workaround of sockets always return -76 

Remove workaround of sockets always return -76 (because it's fixed on IDF now)
Remove delay during handshake (improving stability)

* Remove unusable mbedtls_net of context creation

* Fix bad destructor

* Compatibility with WiFiClient for HTTPClient

* Initial port from ESP8266

Changed SHA1 fingerprint by Root CA verification
Changed log system

* Remove deprecated function

* Support self signed certificates

Fix for https://github.com/espressif/arduino-esp32/issues/265

mbedtls_ssl_conf_authmode was defined before mbedtls_ssl_config_defaults causing several bugs when no CA certificate is defined.

* Implement Arduino's log facility

Replace printf by ESP log handling

* Remove \n from debug messages

log_ doesn't need \n to break line.

* Add CA certificate in example

SHA1 fingerprint is broken now: more info: https://shattered.io

* Best error handling

When occur an error in WiFiClientSecure library just return the error message
and clean the context avoiding crash - fix for https://github.com/espressif/arduino-esp32/issues/211

Translate MbedTLS error codes in messages for best understanding

* Declarate certificates as const

mbedtls_pk_parse_key needs a const unsigned char * certificate. In old implementation the certificate was declarated as char * so first it converts to unsigned and after to const.

When we convert signed to unsigned it may result in a +1 larger output.

Fix issue https://github.com/espressif/arduino-esp32/issues/223

* Provide SSL/TLS functions to ESP32 with Arduino IDE

* Generate a new random number in case of reconnection