http_fopen_wrapper.c - Ignore "100 Continue" responses

ext/standard/http_fopen_wrapper.c

@@ -699,6 +699,24 @@ php_stream *php_stream_url_wrap_http_ex(php_stream_wrapper *wrapper,
 			if ((options & STREAM_ONLY_GET_HEADERS) || ignore_errors) {
 				reqok = 1;
 			}
+
+			/* status codes of 1xx are "informational", and will be followed by a real response
+			 * e.g "100 Continue". RFC 7231 states that unexpected 1xx status MUST be parsed,
+			 * and MAY be ignored. As such, we need to skip ahead to the "real" status*/
+			if (response_code >= 100 && response_code < 200) {
+				/* consume lines until we find a line starting 'HTTP/1' */
+				while (
+					!php_stream_eof(stream)
+					&& php_stream_get_line(stream, tmp_line, sizeof(tmp_line) - 1, &tmp_line_len) != NULL
+					&& ( tmp_line_len < 6 || strncasecmp(tmp_line, "HTTP/1", 6) )
+				);
+
+				if (tmp_line_len > 9) {
+					response_code = atoi(tmp_line + 9);
+				} else {
+					response_code = 0;
+				}
+			}
 			/* all status codes in the 2xx range are defined by the specification as successful;
 			 * all status codes in the 3xx range are for redirection, and so also should never
 			 * fail */

ext/standard/tests/http/bug73297.phpt

@@ -0,0 +1,33 @@
+--TEST--
+Bug #73297 (Ignore 100 Continue returned by HTTP/1.1 servers)
+--INI--
+allow_url_fopen=1
+--SKIPIF--
+<?php require 'server.inc'; http_server_skipif('tcp://127.0.0.1:12342'); ?>
+--FILE--
+<?php
+require 'server.inc';
+
+$options = [
+  'http' => [
+    'protocol_version' => '1.1',
+    'header' => 'Connection: Close'
+  ],
+];
+
+$ctx = stream_context_create($options);
+
+$responses = [
+  "data://text/plain,HTTP/1.1 100 Continue\r\n\r\nHTTP/1.1 200 OK\r\n\r\n"
+    . "Hello"
+];
+$pid = http_server('tcp://127.0.0.1:12342', $responses);
+
+echo file_get_contents('http://127.0.0.1:12342/', false, $ctx);
+echo "\n";
+
+http_server_kill($pid);
+
+?>
+--EXPECT--
+Hello