tls: add function for decoding client_hello

Add function TLSDecodeHandshakeHello() to enable using the same code
for decoding both client_hello and server_hello.

src/app-layer-ssl.c

@@ -230,21 +230,14 @@ int SSLGetAlstateProgress(void *tx, uint8_t direction)
     return TLS_STATE_IN_PROGRESS;
 }
 
-static int SSLv3ParseHandshakeType(SSLState *ssl_state, uint8_t *input,
+static int TLSDecodeHandshakeHello(SSLState *ssl_state, uint8_t *input,
                                    uint32_t input_len)
 {
-    void *ptmp;
     uint8_t *initial_input = input;
-    uint32_t parsed = 0;
-    int rc;
 
-    if (input_len == 0) {
+    /* only parse the message if it is complete */
+    if (input_len < ssl_state->curr_connp->message_length || input_len < 40)
         return 0;
-    }
-
-    switch (ssl_state->curr_connp->handshake_type) {
-        case SSLV3_HS_CLIENT_HELLO:
-            ssl_state->current_flags = SSL_AL_FLAG_STATE_CLIENT_HELLO;
 
     /* skip version */
     input += SSLV3_CLIENT_HELLO_VERSION_LEN;
@@ -352,8 +345,7 @@ static int SSLv3ParseHandshakeType(SSLState *ssl_state, uint8_t *input,
                 if (unlikely(ssl_state->curr_connp->sni == NULL))
                     goto end;
 
-                        memcpy(ssl_state->curr_connp->sni, input,
-                               sni_strlen - 1);
+                memcpy(ssl_state->curr_connp->sni, input, sni_strlen - 1);
                 ssl_state->curr_connp->sni[sni_strlen-1] = 0;
 
                 input += sni_len;
@@ -367,7 +359,32 @@ static int SSLv3ParseHandshakeType(SSLState *ssl_state, uint8_t *input,
         }
         processed_len += ext_len + 4;
     }
+
 end:
+    return 0;
+}
+
+static int SSLv3ParseHandshakeType(SSLState *ssl_state, uint8_t *input,
+                                   uint32_t input_len)
+{
+    void *ptmp;
+    uint8_t *initial_input = input;
+    uint32_t parsed = 0;
+    int rc;
+
+    if (input_len == 0) {
+        return 0;
+    }
+
+    switch (ssl_state->curr_connp->handshake_type) {
+        case SSLV3_HS_CLIENT_HELLO:
+            ssl_state->current_flags = SSL_AL_FLAG_STATE_CLIENT_HELLO;
+
+            rc = TLSDecodeHandshakeHello(ssl_state, input, input_len);
+
+            if (rc < 0)
+                return rc;
+
             break;
 
         case SSLV3_HS_SERVER_HELLO: