Fix multiple begin message cbs when response starts with CR/LF

PR-URL: #432
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Jon Moss <me@jonathanmoss.me>

http_parser.c

@@ -758,21 +758,16 @@ size_t http_parser_execute (http_parser *parser,
 
       case s_start_res:
       {
+        if (ch == CR || ch == LF)
+          break;
         parser->flags = 0;
         parser->content_length = ULLONG_MAX;
 
-        switch (ch) {
-          case 'H':
-            UPDATE_STATE(s_res_H);
-            break;
-
-          case CR:
-          case LF:
-            break;
-
-          default:
-            SET_ERRNO(HPE_INVALID_CONSTANT);
-            goto error;
+        if (ch == 'H') {
+          UPDATE_STATE(s_res_H);
+        } else {
+          SET_ERRNO(HPE_INVALID_CONSTANT);
+          goto error;
         }
 
         CALLBACK_NOTIFY(message_begin);

test.c

@@ -2094,6 +2094,7 @@ int
 message_begin_cb (http_parser *p)
 {
   assert(p == &parser);
+  assert(!messages[num_messages].message_begin_cb_called);
   messages[num_messages].message_begin_cb_called = TRUE;
   return 0;
 }
@@ -4189,6 +4190,7 @@ main (void)
   test_simple_type("HTTP/11.1 200 OK\r\n\r\n", HPE_INVALID_VERSION, HTTP_RESPONSE);
   test_simple_type("HTTP/1.01 200 OK\r\n\r\n", HPE_INVALID_VERSION, HTTP_RESPONSE);
   test_simple_type("HTTP/1.1\t200 OK\r\n\r\n", HPE_INVALID_VERSION, HTTP_RESPONSE);
+  test_simple_type("\rHTTP/1.1\t200 OK\r\n\r\n", HPE_INVALID_VERSION, HTTP_RESPONSE);
 
   for (i = 0; i < ARRAY_SIZE(responses); i++) {
     test_message(&responses[i]);