Send a ClientHello to start TLS negotiation

src/charon/plugins/eap_tls/tls/tls_peer.c

@@ -21,6 +21,11 @@
 
 typedef struct private_tls_peer_t private_tls_peer_t;
 
+typedef enum {
+	STATE_INIT,
+	STATE_HELLO_SENT,
+} peer_state_t;
+
 /**
  * Private data of an tls_peer_t object.
  */
@@ -35,6 +40,11 @@ struct private_tls_peer_t {
 	 * TLS crypto context
 	 */
 	tls_crypto_t *crypto;
+
+	/**
+	 * State we are in
+	 */
+	peer_state_t state;
 };
 
 METHOD(tls_handshake_t, process, status_t,
@@ -43,10 +53,84 @@ METHOD(tls_handshake_t, process, status_t,
 	return NEED_MORE;
 }
 
+/**
+ * Build the Client Hello using a given set of ciphers
+ */
+static chunk_t build_hello(int count, tls_cipher_suite_t *suite, rng_t *rng)
+{
+	int i;
+
+	struct __attribute__((packed)) {
+		u_int16_t version;
+		struct __attribute__((packed)) {
+			u_int32_t gmt;
+			u_int8_t bytes[28];
+		} random;
+		struct __attribute__((packed)) {
+			/* never send a session identifier */
+			u_int8_t len;
+			u_int8_t id[0];
+		} session;
+		struct __attribute__((packed)) {
+			u_int16_t len;
+			u_int16_t suite[count];
+		} cipher;
+		struct __attribute__((packed)) {
+			/* currently NULL compression only */
+			u_int8_t len;
+			u_int8_t method[1];
+		} compression;
+		u_int8_t extensions[0];
+	} hello;
+
+	htoun16(&hello.session.len, 0);
+	htoun16(&hello.version, TLS_1_2);
+	htoun32(&hello.random.gmt, time(NULL));
+	rng->get_bytes(rng, sizeof(hello.random.bytes), (char*)&hello.random.bytes);
+	htoun16(&hello.cipher.len, count * 2);
+	for (i = 0; i < count; i++)
+	{
+		htoun16(&hello.cipher.suite[i], suite[i]);
+	}
+	hello.compression.len = 1;
+	hello.compression.method[0] = 0;
+	return chunk_clone(chunk_create((char*)&hello, sizeof(hello)));
+}
+
+/**
+ * Send a client hello
+ */
+static status_t send_hello(private_tls_peer_t *this,
+						   tls_handshake_type_t *type, chunk_t *data)
+{
+	tls_cipher_suite_t *suite;
+	int count;
+	rng_t *rng;
+
+	rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
+	if (!rng)
+	{
+		return FAILED;
+	}
+	count = this->crypto->get_cipher_suites(this->crypto, &suite);
+	*data = build_hello(count, suite, rng);
+	*type = TLS_CLIENT_HELLO;
+	free(suite);
+	rng->destroy(rng);
+	return NEED_MORE;
+}
+
 METHOD(tls_handshake_t, build, status_t,
 	private_tls_peer_t *this, tls_handshake_type_t *type, chunk_t *data)
 {
-	return INVALID_STATE;
+	switch (this->state)
+	{
+		case STATE_INIT:
+			this->state = STATE_HELLO_SENT;
+			return send_hello(this, type, data);
+		default:
+			return INVALID_STATE;
+	}
 }
 
 METHOD(tls_handshake_t, destroy, void,
@@ -68,6 +152,7 @@ tls_peer_t *tls_peer_create(tls_crypto_t *crypto)
 			.build = _build,
 			.destroy = _destroy,
 		},
+		.state = STATE_INIT,
 		.crypto = crypto,
 	);