Feature/mbedtls (#84)

* try to import mbedtls and build it

* add stubs socket class

* some boilterplate, read and write function implemented

* more boilterplate / current error in handshake because no CA cert is setup

* add something so skip ca verification, can ws curl https://google.com !

* cleanup / close implemented

* tweak CMakefiles

* typo in include

* update readme

* disable unittests

third_party/mbedtls/tests/scripts/key-exchanges.pl

@@ -0,0 +1,62 @@
+#!/usr/bin/env perl
+
+# key-exchanges.pl
+#
+# Copyright (c) 2015-2017, ARM Limited, All Rights Reserved
+#
+# Purpose
+#
+# To test the code dependencies on individual key exchanges in the SSL module.
+# is a verification step to ensure we don't ship SSL code that do not work
+# for some build options.
+#
+# The process is:
+#       for each possible key exchange
+#           build the library with all but that key exchange disabled
+#
+# Usage: tests/scripts/key-exchanges.pl
+#
+# This script should be executed from the root of the project directory.
+#
+# For best effect, run either with cmake disabled, or cmake enabled in a mode
+# that includes -Werror.
+
+use warnings;
+use strict;
+
+-d 'library' && -d 'include' && -d 'tests' or die "Must be run from root\n";
+
+my $sed_cmd = 's/^#define \(MBEDTLS_KEY_EXCHANGE_.*_ENABLED\)/\1/p';
+my $config_h = 'include/mbedtls/config.h';
+my @kexes = split( /\s+/, `sed -n -e '$sed_cmd' $config_h` );
+
+system( "cp $config_h $config_h.bak" ) and die;
+sub abort {
+    system( "mv $config_h.bak $config_h" ) and warn "$config_h not restored\n";
+    # use an exit code between 1 and 124 for git bisect (die returns 255)
+    warn $_[0];
+    exit 1;
+}
+
+for my $kex (@kexes) {
+    system( "cp $config_h.bak $config_h" ) and die "$config_h not restored\n";
+    system( "make clean" ) and die;
+
+    print "\n******************************************\n";
+    print "* Testing with key exchange: $kex\n";
+    print "******************************************\n";
+
+    # full config with all key exchanges disabled except one
+    system( "scripts/config.pl full" ) and abort "Failed config full\n";
+    for my $k (@kexes) {
+        next if $k eq $kex;
+        system( "scripts/config.pl unset $k" )
+            and abort "Failed to disable $k\n";
+    }
+
+    system( "make lib CFLAGS='-Os -Werror'" ) and abort "Failed to build lib: $kex\n";
+}
+
+system( "mv $config_h.bak $config_h" ) and die "$config_h not restored\n";
+system( "make clean" ) and die;
+exit 0;