Add websocket example that supports permessage-deflate extension

examples/websocket_mbedtls/include/mbedtls/config.h

@@ -0,0 +1,27 @@
+/* Special mbedTLS config file for http_get_mbedtls example,
+   overrides supported cipher suite list.
+
+   Overriding the set of cipher suites saves small amounts of ROM and
+   RAM, and is a good practice in general if you know what server(s)
+   you want to connect to.
+
+  However it's extra important here because the howsmyssl API sends
+  back the list of ciphers we send it as a JSON list in the, and we
+  only have a 4096kB receive buffer. If the server supported maximum
+  fragment length option then we wouldn't have this problem either,
+  but we do so this is a good workaround.
+
+  The ciphers chosen below are common ECDHE ciphers, the same ones
+  Firefox uses when connecting to a TLSv1.2 server.
+*/
+#ifndef MBEDTLS_CONFIG_H
+
+/* include_next picks up default config from extras/mbedtls/include/mbedtls/config.h */
+#include_next<mbedtls/config.h>
+
+#define MBEDTLS_SSL_CIPHERSUITES MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,MBEDTLS_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,MBEDTLS_TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
+
+/* uncomment next line to include debug output from example */
+//#define MBEDTLS_DEBUG_C
+
+#endif