Receiving Connection: Proxy-Bypass induces proxy fallback.

net/proxy/proxy_service.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/proxy/proxy_service.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 1156 matching lines @@
 
   // We don't have new proxy settings to try, try to fallback to the next proxy
   // in the list.
   bool did_fallback = result->Fallback(net_log);
 
   // Return synchronous failure if there is nothing left to fall-back to.
   // TODO(eroman): This is a yucky API, clean it up.
   return did_fallback ? OK : ERR_FAILED;
 }
 
+bool ProxyService::MarkProxyAsBad(const ProxyInfo& result,
+                                  const BoundNetLog& net_log) {
+  result.proxy_list_.UpdateRetryInfoOnFallback(&proxy_retry_info_, net_log);
+  // Since we haven't modified proxy_list_, require at least two entries
+  // to return true. With 1 or 0, we won't have any remaining proxy entries
+  // to try after incorporating our bad proxy list, which now includes
+  // the first entry of result.proxy_list_.
+  return result.proxy_list_.size() > 1;

[eroman, 2012/10/08 22:29:25]

I don't believe this is good enough to prevent loops.

Note that the "ProxyRetryInfoMap" is not used to remove proxies from being tried
-- it is only used to "deprioritize" them. In other words, the proxy list will
be re-ordered, and so-called "bad proxies" may still be tried during fallback.

So for instance, if the proxy list was:

"foobar:80; foobar80: foobar80:", then I expect MarkProxyAsBad() would return
true every time, and we would be stuck in a resend loop if the proxy returns
proxy-bypass.

[Michael Piatek, 2012/10/09 21:05:08]

Done.

+}
+
 void ProxyService::ReportSuccess(const ProxyInfo& result) {
   DCHECK(CalledOnValidThread());
 
   const ProxyRetryInfoMap& new_retry_info = result.proxy_retry_info();
   if (new_retry_info.empty())
     return;
 
   for (ProxyRetryInfoMap::const_iterator iter = new_retry_info.begin();
        iter != new_retry_info.end(); ++iter) {
     ProxyRetryInfoMap::iterator existing = proxy_retry_info_.find(iter->first);
@@ skipping 365 matching lines @@
     OnCompletion(result_);
   }
 }
 
 void SyncProxyServiceHelper::OnCompletion(int rv) {
   result_ = rv;
   event_.Signal();
 }
 
 }  // namespace net