allow gzipped data to be passed back to the user in psx proxy mode

fixup the logic for accepting gzip

install/debug.conf.template

@@ -1899,6 +1899,19 @@ ModPagespeedMessagesDomains Allow localhost
   ModPagespeedFileCachePath "@@MOD_PAGESPEED_CACHE@@_mpr"
   ModPagespeedExperimentalProxyAllRequests on
   ModPagespeedExperimentalMeasurementProxy "http://mpr.example.com" secret
+  ModPagespeedFetchWithGzip on
+</VirtualHost>
+
+# For testing measurement proxy things, passthrough.
+<VirtualHost localhost:@@APACHE_SECONDARY_PORT@@>
+  ServerName mprpass.example.com
+  DocumentRoot "@@APACHE_DOC_ROOT@@"
+  ModPagespeedFileCachePath "@@MOD_PAGESPEED_CACHE@@_mprpass"
+  ModPagespeedExperimentalProxyAllRequests on
+  ModPagespeedExperimentalMeasurementProxy "http://mprpass.example.com" secret
+  ModPagespeedFetchWithGzip on
+  ModPagespeedRewriteLevel PassThrough
+  ModPagespeedInPlaceResourceOptimization off
 </VirtualHost>
 
 # For testing how we handle process-scope options.

pagespeed/apache/instaweb_handler.cc

@@ -518,7 +518,6 @@ bool InstawebHandler::HandleAsProxy() {
 }
 
 void InstawebHandler::HandleAsProxyForAll() {
-  static const char kLoopHeader[] = "X-PageSpeed-Loop";
   static const char kLoopValue[] = "MPS";
 
   // Note: we can't use MakeFetch here as we want ProxyInterface to create the
@@ -527,14 +526,13 @@ void InstawebHandler::HandleAsProxyForAll() {
   ApacheRequestToRequestHeaders(*request_, request_headers.get());
 
   // Do loop detection.
-  if (request_headers->HasValue(kLoopHeader, kLoopValue)) {
+  if (request_headers->HasValue(HttpAttributes::kXPageSpeedLoop, kLoopValue)) {
     write_handler_response("Loop detected on fetch in ProxyAllRequests mode; "
                            "you may need to authorize more domains. ",
                            request_);
     return;
   }
-  request_headers->Add(kLoopHeader, kLoopValue);
-
+  request_headers->Add(HttpAttributes::kXPageSpeedLoop, kLoopValue);
   SimpleBufferedApacheFetch fetch(request_context_,
                                   request_headers.release(),
                                   server_context_->thread_system(),

pagespeed/apache/system_test.sh

@@ -1052,6 +1052,19 @@ if [ "$SECONDARY_HOSTNAME" != "" ]; then
   OUT=$($CURL --silent --include --proxy $SECONDARY_HOSTNAME\
       http://mpr.example.com/h/b/secret/www.gstatic.com/psa/static/A.0e5d6484d7bf84edf94c17a8d6a6c6de-mobilize.css+0f58e3ef023072001e64bba88abaeeeb-mobilize.css,Mcc.JzQiGpc0_X.css.pagespeed.cf.0slDU6deBr.css)
   check_from "$OUT" fgrep -q "psmob-map-button"
+
+  start_test Measurement proxy mode passthrough gzip
+  URL="http://mprpass.example.com/h/b/secret/www.gstatic.com/psa/static/57ea3579bb97c7b4ca6658061d5c765b-mobilize.js"
+  http_proxy=${SECONDARY_HOSTNAME} fetch_until -gzip $URL "wc -c" 69551 "" -le
+  start_test Measurement proxy mode rewrite gzip
+  URL="http://mpr.example.com/h/b/secret/www.gstatic.com/psa/static/57ea3579bb97c7b4ca6658061d5c765b-mobilize.js"
+  http_proxy=${SECONDARY_HOSTNAME} fetch_until -gzip $URL "wc -c" 65151 "" -le
+  start_test Measurement proxy mode passthrough nogzip
+  URL="http://mprpass.example.com/h/b/secret/www.gstatic.com/psa/static/57ea3579bb97c7b4ca6658061d5c765b-mobilize.js"
+  http_proxy=${SECONDARY_HOSTNAME} fetch_until $URL "wc -c" 288467 "" -ge
+  start_test Measurement proxy mode rewrite nogzip
+  URL="http://mpr.example.com/h/b/secret/www.gstatic.com/psa/static/57ea3579bb97c7b4ca6658061d5c765b-mobilize.js"
+  http_proxy=${SECONDARY_HOSTNAME} fetch_until $URL "wc -c" 241055 "" -ge
 fi
 
 start_test Make sure Disallow/Allow overrides work in htaccess hierarchies

pagespeed/automatic/proxy_interface.cc

@@ -267,7 +267,13 @@ void ProxyInterface::GetRewriteOptionsDone(RequestData* request_data,
 
   // Update request_headers.
   // We deal with encodings. So strip the users Accept-Encoding headers.
-  async_fetch->request_headers()->RemoveAll(HttpAttributes::kAcceptEncoding);
+  if (!async_fetch->request_headers()->Lookup1(
+          HttpAttributes::kXPageSpeedLoop)) {
+    // In proxy mode (mpr) we must pass through the accept encoding to be able
+    // to tell if the origin server is sending gzipped content when the client
+    // is requesting it.
+    async_fetch->request_headers()->RemoveAll(HttpAttributes::kAcceptEncoding);
+  }
   // Note: We preserve the User-Agent and Cookies so that the origin servers
   // send us the correct HTML. We will need to consider this for caching HTML.
 

pagespeed/kernel/http/headers.cc

@@ -275,6 +275,7 @@ bool IsCommaSeparatedField(const StringPiece& name) {
       StringCaseEqual(name, HttpAttributes::kCacheControl) ||
       StringCaseEqual(name, HttpAttributes::kContentEncoding) ||
       StringCaseEqual(name, HttpAttributes::kConnection) ||
+      StringCaseEqual(name, HttpAttributes::kAcceptEncoding) ||
       StringCaseEqual(name, HttpAttributes::kVary)) {
     return true;
   } else {

pagespeed/kernel/http/http_names.cc

@@ -125,6 +125,7 @@ const char HttpAttributes::kXUACompatible[] = "X-UA-Compatible";
 const char HttpAttributes::kXPsaSplitConfig[] = "X-PSA-Split-Config";
 const char HttpAttributes::kXSendfile[] = "X-Sendfile";
 const char HttpAttributes::kXAccelRedirect[] = "X-Accel-Redirect";
+const char HttpAttributes::kXPageSpeedLoop[] = "X-PageSpeed-Loop";
 
 const char* HttpStatus::GetReasonPhrase(HttpStatus::Code rc) {
   switch (rc) {

pagespeed/kernel/http/http_names.h

@@ -153,6 +153,8 @@ struct HttpAttributes {
   // Sendfile type responses.
   static const char kXSendfile[];
   static const char kXAccelRedirect[];
+  // PageSpeed Loop detection for proxy mode.
+  static const char kXPageSpeedLoop[];
 
   // Gets a sorted StringPieceVector containing all the end-to-end headers.
   // Any fields listed in here should be ignored during sanitization when they