Fix possible bypass-retry loop for 4xx responses with missing Via header

Data reduction proxy can get stuck in a bypass-retry loop on slow
networks with >1second RTT, for the URL requests returning 4XX error.
The reason is due to the 1-second bypass triggered on 4xx errors with no
Via header.

The fix is to change the 1-second bypass to block-once for the current
request.

BUG=502045

Review URL: https://codereview.chromium.org/1766633002

Cr-Commit-Position: refs/heads/master@{#380044}

4 files changed, 48 insertions, 10 deletions

diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol_unittest.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol_unittest.cc
index aff833d..ff58e6c 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol_unittest.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol_unittest.cc
@@ -536,9 +536,9 @@ TEST_F(DataReductionProxyProtocolTest, BypassLogic) {
       "Server: proxy\r\n\r\n",
       true,
       false,
-      1u,
+      0u,
       true,
-      1,
+      0,
       BYPASS_EVENT_TYPE_MISSING_VIA_HEADER_4XX
     },
     // Invalid data reduction proxy response. Missing Via header.
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_stats_unittest.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_stats_unittest.cc
index 0deda3d..b6469ba 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_stats_unittest.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_stats_unittest.cc
@@ -888,9 +888,6 @@ TEST_F(DataReductionProxyBypassStatsEndToEndTest,
     const char* initial_response_headers;
   };
   const TestCase test_cases[] = {
-    { "DataReductionProxy.BypassedBytes.MissingViaHeader4xx",
-      "HTTP/1.1 414 Request-URI Too Long\r\n\r\n",
-    },
     { "DataReductionProxy.BypassedBytes.MissingViaHeaderOther",
       "HTTP/1.1 200 OK\r\n\r\n",
     },
@@ -952,4 +949,42 @@ TEST_F(DataReductionProxyBypassStatsEndToEndTest, BypassedBytesNetErrorOther) {
       -net::ERR_PROXY_CONNECTION_FAILED, 1);
 }
 
+TEST_F(DataReductionProxyBypassStatsEndToEndTest,
+       BypassedBytesMissingViaHeader4xx) {
+  InitializeContext();
+  const char* test_case_response_headers[] = {
+      "HTTP/1.1 414 Request-URI Too Long\r\n\r\n",
+      "HTTP/1.1 404 Not Found\r\n\r\n",
+  };
+  for (const char* test_case : test_case_response_headers) {
+    ClearBadProxies();
+    // The first request should be bypassed for missing Via header.
+    {
+      base::HistogramTester histogram_tester;
+      CreateAndExecuteRequest(GURL("http://foo.com"), test_case,
+                              kErrorBody.c_str(), "HTTP/1.1 200 OK\r\n\r\n",
+                              kBody.c_str());
+
+      histogram_tester.ExpectUniqueSample(
+          "DataReductionProxy.BypassedBytes.MissingViaHeader4xx", kBody.size(),
+          1);
+      ExpectOtherBypassedBytesHistogramsEmpty(
+          histogram_tester,
+          "DataReductionProxy.BypassedBytes.MissingViaHeader4xx");
+    }
+    // The second request should be sent via the proxy.
+    {
+      base::HistogramTester histogram_tester;
+      CreateAndExecuteRequest(GURL("http://bar.com"),
+                              "HTTP/1.1 200 OK\r\n"
+                              "Via: 1.1 Chrome-Compression-Proxy\r\n\r\n",
+                              kNextBody.c_str(), nullptr, nullptr);
+      histogram_tester.ExpectUniqueSample(
+          "DataReductionProxy.BypassedBytes.NotBypassed", kNextBody.size(), 1);
+      ExpectOtherBypassedBytesHistogramsEmpty(
+          histogram_tester, "DataReductionProxy.BypassedBytes.NotBypassed");
+    }
+  }
+}
+
 }  // namespace data_reduction_proxy
diff --git a/components/data_reduction_proxy/core/common/data_reduction_proxy_headers.cc b/components/data_reduction_proxy/core/common/data_reduction_proxy_headers.cc
index 8945a02..fa9b6da 100644
--- a/components/data_reduction_proxy/core/common/data_reduction_proxy_headers.cc
+++ b/components/data_reduction_proxy/core/common/data_reduction_proxy_headers.cc
@@ -258,10 +258,10 @@ DataReductionProxyBypassType GetDataReductionProxyBypassType(
         headers->response_code() < net::HTTP_INTERNAL_SERVER_ERROR) {
       // At this point, any 4xx response that is missing the via header
       // indicates an issue that is scoped to only the current request, so only
-      // bypass the data reduction proxy for a second.
-      // TODO(sclittle): Change this to only bypass the current request once
-      // that is fully supported, see http://crbug.com/418342.
-      data_reduction_proxy_info->bypass_duration = TimeDelta::FromSeconds(1);
+      // bypass the data reduction proxy for the current request.
+      data_reduction_proxy_info->bypass_all = true;
+      data_reduction_proxy_info->mark_proxies_as_bad = false;
+      data_reduction_proxy_info->bypass_duration = TimeDelta();
       return BYPASS_EVENT_TYPE_MISSING_VIA_HEADER_4XX;
     }
 
diff --git a/components/data_reduction_proxy/core/common/data_reduction_proxy_headers.h b/components/data_reduction_proxy/core/common/data_reduction_proxy_headers.h
index f243675..44f4528 100644
--- a/components/data_reduction_proxy/core/common/data_reduction_proxy_headers.h
+++ b/components/data_reduction_proxy/core/common/data_reduction_proxy_headers.h
@@ -34,7 +34,10 @@ enum DataReductionProxyBypassType {
 };
 
 // Values for the bypass actions that can be specified by the Data Reduction
-// Proxy in response to a client request.
+// Proxy in response to a client request. These are explicit bypass actions
+// specified by the Data Reduction Proxy in the Chrome-Proxy header, block-once,
+// bypass=1, block=300, etc. These are not used for Chrome initiated bypasses
+// due to a server error, missing Via header, etc.
 enum DataReductionProxyBypassAction {
 #define BYPASS_ACTION_TYPE(label, value) BYPASS_ACTION_TYPE_##label = value,
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_bypass_action_list.h"