Add on_status_complete callback.

Add a "status complete" callback to support Simple-Response handling with HTTP
version <= 1.0.

Patch by Tóth Tamás, tests by Corey Richardson.

http_parser.c

@@ -866,6 +866,7 @@ size_t http_parser_execute (http_parser *parser,
       case s_res_line_almost_done:
         STRICT_CHECK(ch != LF);
         parser->state = s_header_field_start;
+        CALLBACK_NOTIFY(status_complete);
         break;
 
       case s_start_req:

http_parser.h

@@ -141,6 +141,7 @@ enum flags
                                                                      \
   /* Callback-related errors */                                      \
   XX(CB_message_begin, "the on_message_begin callback failed")       \
+  XX(CB_status_complete, "the on_status_complete callback failed")   \
   XX(CB_url, "the on_url callback failed")                           \
   XX(CB_header_field, "the on_header_field callback failed")         \
   XX(CB_header_value, "the on_header_value callback failed")         \
@@ -221,6 +222,7 @@ struct http_parser {
 struct http_parser_settings {
   http_cb      on_message_begin;
   http_data_cb on_url;
+  http_cb      on_status_complete;
   http_data_cb on_header_field;
   http_data_cb on_header_value;
   http_cb      on_headers_complete;

test.c

@@ -1491,6 +1491,13 @@ request_url_cb (http_parser *p, const char *buf, size_t len)
   return 0;
 }
 
+int
+status_complete_cb (http_parser *p) {
+  assert(p == parser);
+  p->data++;
+  return 0;
+}
+
 int
 header_field_cb (http_parser *p, const char *buf, size_t len)
 {
@@ -3089,6 +3096,20 @@ create_large_chunked_message (int body_size_in_kb, const char* headers)
   return buf;
 }
 
+void
+test_status_complete (void)
+{
+  parser_init(HTTP_RESPONSE);
+  parser->data = 0;
+  http_parser_settings settings = settings_null;
+  settings.on_status_complete = status_complete_cb;
+
+  char *response = "don't mind me, just a simple response";
+  http_parser_execute(parser, &settings, response, strlen(response));
+  assert(parser->data == (void*)0); // the status_complete callback was never called
+  assert(parser->http_errno == HPE_INVALID_CONSTANT); // the errno for an invalid status line
+}
+
 /* Verify that we can pause parsing at any of the bytes in the
  * message and still get the result that we're expecting. */
 void
@@ -3396,6 +3417,8 @@ main (void)
            , &requests[CONNECT_REQUEST]
            );
 
+  test_status_complete();
+
   puts("requests okay");
 
   return 0;