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Unified Diff: net/filter/sdch_policy_delegate.cc

Issue 1662763002: [ON HOLD] Implement pull-based design for content decoding (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Created 4 years, 10 months ago
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« net/filter/gzip_stream_source.cc ('K') | « net/filter/sdch_policy_delegate.h ('k') | net/filter/sdch_policy_delegate_unittest.cc » ('j') | net/filter/stream_source.h » ('J')
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Index: net/filter/sdch_policy_delegate.cc
diff --git a/net/filter/sdch_policy_delegate.cc b/net/filter/sdch_policy_delegate.cc
new file mode 100644
index 0000000000000000000000000000000000000000..acfc8822c387c6c5ad1884e88a9c66aa4fda53bc
--- /dev/null
+++ b/net/filter/sdch_policy_delegate.cc
@@ -0,0 +1,226 @@
+// Copyright 2016 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 "base/metrics/histogram_macros.h"
+#include "net/filter/sdch_policy_delegate.h"
+#include "net/filter/sdch_stream_source.h"
+
+namespace {
+
+const char kRefreshHtml[] =
+ "<head><META HTTP-EQUIV=\"Refresh\" CONTENT=\"0\"></head>";
+
+// Measures the eventual fate of the stream handled by this delegate.
+enum StreamFate {
+ STREAM_FATE_OK,
+ STREAM_FATE_STOP_DECODING,
+ STREAM_FATE_REFRESH,
+ STREAM_FATE_FAIL
+};
+
+// Causes for the fates given above. FATE_OK is always CAUSE_NONE.
+enum StreamFateCause {
+ STREAM_FATE_CAUSE_NONE,
+ STREAM_FATE_CAUSE_404,
+ STREAM_FATE_CAUSE_NOT_200,
+ STREAM_FATE_CAUSE_OLD_UNENCODED,
+ STREAM_FATE_CAUSE_TENTATIVE_SDCH,
+ STREAM_FATE_CAUSE_NO_DICTIONARY,
+ STREAM_FATE_CAUSE_CORRUPT_SDCH,
+ STREAM_FATE_CAUSE_ENCODING_LIE,
+ STREAM_FATE_CAUSE_MAX
+};
+
+} // namespace
+
+namespace net {
+
+SdchPolicyDelegate::SdchPolicyDelegate(scoped_ptr<Context> context)
+ : dictionary_requested_(false),
+ context_(std::move(context)),
+ did_meta_refresh_(false),
+ did_stop_decoding_(false),
+ did_fail_request_(false) {}
+
+SdchPolicyDelegate::~SdchPolicyDelegate() {}
+
+// Dictionary errors are often the first indication that the SDCH stream has
+// become corrupt. There are many possible causes: non-200 response codes, a
+// cached non-SDCH-ified reply, the server opting not to use SDCH, a cached
+// SDCH-ified reply for which the SdchManager did not have the dictionary, a
+// corrupted response, or a response that claims to be SDCH but isn't actually.
+// These are handled here by issuing a meta-refresh or swapping to passthrough
+// mode if appropriate, or failing the request if the error is unrecoverable.
+bool SdchPolicyDelegate::HandleDictionaryError(SdchStreamSource* source) {
+ GURL url;
+ if (!context_->GetURL(&url)) {
+ did_fail_request_ = true;
+ return false;
+ }
+
+ LogSdchDictionaryError();
+
+ // HTTP 404 might be an unencoded error page, so if decoding failed, pass it
+ // through. TODO(516773)
+ if (context_->GetResponseCode() == 404) {
+ did_stop_decoding_ = true;
+ source->StopDecoding();
+ return true;
+ }
+
+ // HTTP !200 gets a meta-refresh for HTML and a hard failure otherwise.
+ if (context_->GetResponseCode() != 200)
+ return IssueMetaRefreshIfPossible(source);
+
+ // If this is a cached result and the source hasn't requested a dictionary, it
+ // probably never had a dictionary to begin and is an unencoded response from
+ // earlier. If the source has requested a dictionary, but there was still a
+ // dictionary error, then the SdchManager does not have it so this method
+ // needs to issue a meta-refresh to get it.
+ if (context_->IsCachedContent() && !dictionary_requested_) {
+ did_stop_decoding_ = true;
+ source->StopDecoding();
+ return true;
+ }
+
+ // Ow. The original request didn't advertise any dictionaries, but the
+ // response claimed to be SDCH, but did not have a plausible dictionary hash.
+ // There is no way to repair this situation: the original request already
+ // didn't advertise any dictionaries, and retrying it would likely have the
+ // same result. Blacklist the domain and try passing through.
+ if (!context_->SdchDictionariesAdvertised() && !dictionary_requested_) {
+ did_stop_decoding_ = true;
+ source->StopDecoding();
+ context_->GetSdchManager()->BlacklistDomain(url,
+ SDCH_PASSING_THROUGH_NON_SDCH);
+ return true;
+ }
+
+ return IssueMetaRefreshIfPossible(source);
+}
+
+// A decoding error, as opposed to a dictionary error, indicates a decompression
+// failure partway through the payload of the SDCH stream, which means that the
+// filter already witnessed a valid dictionary ID and successfully retrieved a
+// dictionary for it. Decoding errors are not recoverable and it is not
+// appropriate to stop decoding, so there are relatively few error cases here.
+//
+// In particular, a decoding error for an HTML payload is recoverable by issuing
+// a meta-refresh, but to avoid having that happen too often, this class also
+// temporarily blacklists the domain. A decoding error for a non-HTML payload is
+// unrecoverable, so such an error gets a permanent blacklist entry. If the
+// content was cached, no blacklisting is needed.
+bool SdchPolicyDelegate::HandleDecodingError(SdchStreamSource* source) {
+ LogSdchDecodingError();
+ return IssueMetaRefreshIfPossible(source);
+}
+
+bool SdchPolicyDelegate::GetDictionary(const std::string& server_id,
+ const std::string** text) {
+ dictionary_requested_ = true;
+ SdchManager::DictionarySet* set = context_->SdchDictionariesAdvertised();
+ if (set) {
+ *text = set->GetDictionaryText(server_id);
+ if (!(*text)->empty()) {
+ LOG(ERROR) << "GetDictionary success!";
+ return true;
+ }
+ }
+ GURL url;
+ if (!context_->GetURL(&url))
+ return false;
+ SdchProblemCode rv = SDCH_OK;
+ unexpected_dictionary_set_ =
+ context_->GetSdchManager()->GetDictionarySetByHash(url, server_id, &rv);
+ if (unexpected_dictionary_set_) {
+ *text = unexpected_dictionary_set_->GetDictionaryText(server_id);
+ // XXX: log fallback here (UNADVERTISED_DICTIONARY_USED etc)
+ if (!(*text)->empty())
+ return true;
+ }
+ // XXX: check for HASH_NOT_FOUND / HASH_MALFORMED here? or in
+ // SdchStreamSource?
+ return false;
+}
+
+void SdchPolicyDelegate::NotifyStreamDone() {
+// Don't understand what to do with these.
+#if 0
+ if (did_fail_request_)
+ UMA_HISTOGRAM_COUNTS("Sdch4.StreamFate", STREAM_FATE_FAIL);
+ else if (did_meta_refresh_)
+ UMA_HISTOGRAM_COUNTS("Sdch4.StreamFate", STREAM_FATE_REFRESH);
+ else if (did_stop_decoding_)
+ UMA_HISTOGRAM_COUNTS("Sdch4.StreamFate", STREAM_FATE_STOP_DECODING);
+ else
+ UMA_HISTOGRAM_COUNTS("Sdch4.StreamFate", STREAM_FATE_OK);
+#endif
+}
+
+bool SdchPolicyDelegate::IssueMetaRefreshIfPossible(SdchStreamSource* source) {
+ std::string mime_type;
+ if (!context_->GetMimeType(&mime_type)) {
+ did_fail_request_ = true;
+ return false;
+ }
+ GURL url;
+ if (!context_->GetURL(&url)) {
+ did_fail_request_ = true;
+ return false;
+ }
+ SdchManager* manager = context_->GetSdchManager();
+
+ // Errors for non-HTML payloads are unrecoverable and get the domain
+ // blacklisted indefinitely.
+ if (mime_type.npos == mime_type.find("text/html")) {
+ SdchProblemCode problem =
+ (context_->IsCachedContent() ? SDCH_CACHED_META_REFRESH_UNSUPPORTED
+ : SDCH_META_REFRESH_UNSUPPORTED);
+ manager->BlacklistDomainForever(url, problem);
+ did_fail_request_ = true;
+ return false;
+ }
+
+ if (!context_->IsCachedContent())
+ manager->BlacklistDomain(url, SDCH_META_REFRESH_RECOVERY);
+
+ source->ReplaceOutput(kRefreshHtml, strlen(kRefreshHtml));
+ did_meta_refresh_ = true;
+ return true;
+}
+
+// Old histograms: Sdch3.
+// FilterUseBeforeDisabling
+// PartialBytesIn, PartialVcdiffIn, PartialVcdiffOut
+// UnflushedBytesIn, UnflushedBufferSize, UnflushedVcdiffIn,
+// UnflushedVcdiffOut
+// Network_Decode_Ratio_a
+// Network_Decode_Bytes_VcdiffOut_a
+// NetworkBytesSavedByCompression
+// ResponseCorruptionDetection.{Cached,Uncached}
+
+// Decoding errors only produce Sdch3.ResponseCorruptionDetection histograms. To
+// have a decoding error, the dictionary header must have been valid, and the
+// dictionary must have been loaded successfully, but the response doesn't
+// decode successfully, so it is corrupt.
+void SdchPolicyDelegate::LogSdchDecodingError() {
+ if (context_->IsCachedContent()) {
+ UMA_HISTOGRAM_ENUMERATION("Sdch3.ResponseCorruptionDetection.Cached",
+ STREAM_FATE_CAUSE_CORRUPT_SDCH,
+ STREAM_FATE_CAUSE_MAX);
+ } else {
+ UMA_HISTOGRAM_ENUMERATION("Sdch3.ResponseCorruptionDetection.Uncached",
+ STREAM_FATE_CAUSE_CORRUPT_SDCH,
+ STREAM_FATE_CAUSE_MAX);
+ }
+}
+
+void SdchPolicyDelegate::LogSdchDictionaryError() {
+ std::string mime_type;
+ if (!context_->GetMimeType(&mime_type))
+ return;
+ // TODO(ellyjones): figure out what stats to gather here
+}
+
+} // namespace net
« net/filter/gzip_stream_source.cc ('K') | « net/filter/sdch_policy_delegate.h ('k') | net/filter/sdch_policy_delegate_unittest.cc » ('j') | net/filter/stream_source.h » ('J')

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