Multiple Vary headers hotfix Hans

multiple-vary-hans-hotfix.patch

diff --git a/src/ngx_pagespeed.cc b/src/ngx_pagespeed.cc
index 1f8f2e2..4fc26ed 100644
--- a/src/ngx_pagespeed.cc
+++ b/src/ngx_pagespeed.cc
@@ -492,7 +492,6 @@ ngx_int_t copy_response_headers_to_ngx(
   for (i = 0 ; i < pagespeed_headers.NumAttributes() ; i++) {
     const GoogleString& name_gs = pagespeed_headers.Name(i);
     const GoogleString& value_gs = pagespeed_headers.Value(i);
-
     if (preserve_caching_headers == kPreserveAllCachingHeaders) {
       if (StringCaseEqual(name_gs, "ETag") ||
           StringCaseEqual(name_gs, "Expires") ||
@@ -570,6 +569,16 @@ ngx_int_t copy_response_headers_to_ngx(
       continue;
     } else if (STR_EQ_LITERAL(name, "Transfer-Encoding")) {
       continue;
+    } else if (STR_EQ_LITERAL(name, "Vary") && value.len
+        && STR_EQ_LITERAL(value, "Accept-Encoding")) {
+      ps_request_ctx_t* ctx = ps_get_request_context(r);
+      // TODO(oschaaf): temporary hack to prevent cascading that PSOL emits 
+      // multiple Vary: Accept-Encoding headers. Remove this once the PSOL fix
+      // is released.
+      if ( ctx->psol_vary_accept_only ) {
+        continue;
+      }
+      ctx->psol_vary_accept_only = true;
     }
 
     u_char* name_s = ngx_pstrdup(r->pool, &name);
@@ -1268,6 +1277,7 @@ ngx_int_t ps_decline_request(ngx_http_request_t* r) {
   ctx->driver->Cleanup();
   ctx->driver = NULL;
   ctx->location_field_set = false;
+  ctx->psol_vary_accept_only = false;
 
   // re init ctx
   ctx->html_rewrite = true;
@@ -1838,6 +1848,7 @@ ngx_int_t ps_resource_handler(ngx_http_request_t* r,
     ctx->recorder = NULL;
     ctx->url_string = url_string;
     ctx->location_field_set = false;
+    ctx->psol_vary_accept_only = false;
 
     // Set up a cleanup handler on the request.
     ngx_http_cleanup_t* cleanup = ngx_http_cleanup_add(r, 0);
@@ -2155,6 +2166,13 @@ ngx_int_t ps_etag_header_filter(ngx_http_request_t* r) {
       break;
     }
   }
+
+  ps_request_ctx_t* ctx = ps_get_request_context(r);
+#if (NGX_HTTP_GZIP)
+  if (ctx && ctx->psol_vary_accept_only) {
+    r->gzip_vary = 0;
+  }
+#endif
   return ngx_http_ef_next_header_filter(r);
 }
 
diff --git a/src/ngx_pagespeed.h b/src/ngx_pagespeed.h
index cae895a..a531bc3 100644
--- a/src/ngx_pagespeed.h
+++ b/src/ngx_pagespeed.h
@@ -108,6 +108,7 @@ typedef struct {
   // we should mirror that when we write it back. nginx may absolutify
   // Location: headers that start with '/' without regarding X-Forwarded-Proto.
   bool location_field_set;
+  bool psol_vary_accept_only;
 } ps_request_ctx_t;
 
 ps_request_ctx_t* ps_get_request_context(ngx_http_request_t* r);
diff --git a/test/nginx_system_test.sh b/test/nginx_system_test.sh
index ff52a7c..5bd8984 100644
--- a/test/nginx_system_test.sh
+++ b/test/nginx_system_test.sh
@@ -1241,6 +1241,22 @@ check_from "$OUT" fgrep -qi '404'
 MATCHES=$(echo "$OUT" | grep -c "Cache-Control: override") || true
 check [ $MATCHES -eq 1 ]
 
+start_test Single Vary: Accept-Encoding header in IPRO flow
+URL=http://psol-vary.example.com/mod_pagespeed_example/styles/index_style.css
+OUT=$(http_proxy=$SECONDARY_HOSTNAME $WGET_DUMP -O /dev/null -S $URL 2>&1)
+# First hit will be recorded and passed on untouched
+MATCHES=$(echo "$OUT" | grep -c "Vary: Accept-Encoding") || true
+check [ $MATCHES -eq 1 ]
+
+# Fetch until we get a fully optimized response
+http_proxy=$SECONDARY_HOSTNAME \
+  fetch_until $URL "fgrep -c W/\"PSA" 1 --save-headers
+
+# Test the optimized response.
+OUT=$(http_proxy=$SECONDARY_HOSTNAME $WGET_DUMP -O /dev/null -S $URL 2>&1)
+MATCHES=$(echo "$OUT" | grep -c "Vary: Accept-Encoding") || true
+check [ $MATCHES -eq 1 ]
+
 start_test Shutting down.
 
 # Fire up some heavy load if ab is available to test a stressed shutdown
diff --git a/test/pagespeed_test.conf.template b/test/pagespeed_test.conf.template
index d05f92a..35a7616 100644
--- a/test/pagespeed_test.conf.template
+++ b/test/pagespeed_test.conf.template
@@ -1463,6 +1463,14 @@ http {
     pagespeed GlobalAdminDomains
      Allow everything-explicitly-allowed.example.com;
   }
+  server {
+    listen @@SECONDARY_PORT@@;
+    listen [::]:@@SECONDARY_PORT@@;
+    server_name psol-vary.example.com;
+    pagespeed on;
+    pagespeed InPlaceResourceOptimization on;
+    pagespeed FileCachePath "@@FILE_CACHE@@";
+  }
 
   server {
     listen @@PRIMARY_PORT@@;