SanitizeProxyAuth: Whitelist all hop-by-hop headers

net/http/proxy_client_socket.cc

Index: net/http/proxy_client_socket.cc
diff --git a/net/http/proxy_client_socket.cc b/net/http/proxy_client_socket.cc
index 3c539c6895e295a98f9645070e4258bbf78b5d73..3c0d12d5cb2ada770a0e8114c867a44c1fe059fd 100644
--- a/net/http/proxy_client_socket.cc
+++ b/net/http/proxy_client_socket.cc
@@ -95,9 +95,19 @@ bool ProxyClientSocket::SanitizeProxyAuth(HttpResponseInfo* response) {
   scoped_refptr<HttpResponseHeaders> new_headers = new HttpResponseHeaders(
       HttpUtil::AssembleRawHeaders(kHeaders, arraysize(kHeaders)));
 
+  // Copy status line and all hop-by-hop headers to preserve keep-alive
+  // behavior.

[wtc, 2015/03/06 02:22:40]

The comment for ProxyClientSocket::SanitizeProxyAuth in proxy_client_socket.h
should be updated. In particular, that comment should say which headers (at
least give some representative examples) must be stripped and why (for security
reasons?).

   new_headers->ReplaceStatusLine(old_headers->GetStatusLine());
-  CopyHeaderValues(old_headers, new_headers, "Connection");
-  CopyHeaderValues(old_headers, new_headers, "Proxy-Authenticate");
+  CopyHeaderValues(old_headers, new_headers, "connection");
+  CopyHeaderValues(old_headers, new_headers, "proxy-connection");
+  CopyHeaderValues(old_headers, new_headers, "keep-alive");
+  CopyHeaderValues(old_headers, new_headers, "trailer");
+  CopyHeaderValues(old_headers, new_headers, "transfer-encoding");
+  CopyHeaderValues(old_headers, new_headers, "upgrade");
+
+  CopyHeaderValues(old_headers, new_headers, "content-length");
+
+  CopyHeaderValues(old_headers, new_headers, "proxy-authenticate");

[wtc, 2015/03/06 02:22:40]

This list of headers looks very ad hoc to me. I'm curious how you determined
which headers must be copied. Some are obvious, such as "proxy-connection" and
"keep-alive", which are needed for keep-alive/persistent connections. Perhaps we
can group the headers, something like:

  // For keep-alive/persistent connections
  ... "connection");
  ... "proxy-connection");
  ... "keep-alive");

  // For chunked encoding or content length.
  ... "trailer");
  ... "transfer-encoding");
  ... "content-length");

  etc.

 
   response->headers = new_headers;
   return true;