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1 // Copyright 2016 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "net/filter/sdch_policy_delegate.h" | |
6 | |
7 #include "base/metrics/histogram_macros.h" | |
8 #include "base/strings/string_util.h" | |
9 #include "base/values.h" | |
10 #include "net/base/sdch_net_log_params.h" | |
11 #include "net/base/sdch_problem_codes.h" | |
12 #include "net/log/net_log.h" | |
13 #include "net/log/net_log_event_type.h" | |
14 #include "net/url_request/url_request_http_job.h" | |
15 #include "sdch/open-vcdiff/src/google/vcdecoder.h" | |
16 | |
17 namespace net { | |
18 | |
19 namespace { | |
20 | |
21 const char kRefreshHtml[] = | |
22 "<head><META HTTP-EQUIV=\"Refresh\" CONTENT=\"0\"></head>"; | |
23 // Mime types: | |
24 const char kTextHtml[] = "text/html"; | |
25 | |
26 } // namespace | |
27 | |
28 SdchPolicyDelegate::SdchPolicyDelegate( | |
29 URLRequestHttpJob* job, | |
30 std::string mime_type, | |
31 const GURL& url, | |
32 bool is_cached_content, | |
33 SdchManager* sdch_manager, | |
34 std::unique_ptr<SdchManager::DictionarySet> dictionary_set, | |
35 int response_code, | |
36 const NetLogWithSource& net_log) | |
37 : job_(job), | |
38 mime_type_(mime_type), | |
39 url_(url), | |
40 is_cached_content_(is_cached_content), | |
41 sdch_manager_(sdch_manager), | |
42 dictionary_set_(std::move(dictionary_set)), | |
43 response_code_(response_code), | |
44 net_log_(net_log) {} | |
45 | |
46 SdchPolicyDelegate::~SdchPolicyDelegate() {} | |
47 | |
48 // static | |
49 void SdchPolicyDelegate::FixUpSdchContentEncodings( | |
50 const NetLogWithSource& net_log, | |
51 const std::string& mime_type, | |
52 SdchManager::DictionarySet* dictionary_set, | |
53 std::vector<SourceStream::SourceType>* types) { | |
54 // If content encoding included SDCH, then everything is "relatively" fine. | |
55 if (!types->empty() && types->front() == SourceStream::TYPE_SDCH) { | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:25
This looks to me like a functionality change? In
xunjieli
2016/10/14 18:23:34
Done. Sorry about that! Now it should match to Fix
| |
56 // Some proxies (found currently in Argentina) strip the Content-Encoding | |
57 // text from "sdch,gzip" to a mere "sdch" without modifying the compressed | |
58 // payload. To handle this gracefully, we simulate the "probably" deleted | |
59 // ",gzip" by appending a tentative gzip decode, which will default to a | |
60 // no-op pass through filter if it doesn't get gzip headers where | |
61 // expected. | |
62 if (1 == types->size()) { | |
63 types->push_back(SourceStream::TYPE_GZIP_FALLBACK); | |
64 LogSdchProblem(net_log, SDCH_OPTIONAL_GUNZIP_ENCODING_ADDED); | |
65 } | |
66 return; | |
67 } | |
68 | |
69 // If sdch dictionary is advertised, we might need to add some decoding, as | |
70 // some proxies strip encoding completely. | |
71 if (!dictionary_set) | |
72 return; | |
73 | |
74 // There are now several cases to handle for an SDCH request. Foremost, if | |
75 // the outbound request was stripped so as not to advertise support for | |
76 // encodings, we might get back content with no encoding, or (for example) | |
77 // just gzip. We have to be sure that any changes we make allow for such | |
78 // minimal coding to work. That issue is why we use TENTATIVE filters if we | |
79 // add any, as those filters sniff the content, and act as pass-through | |
80 // filters if headers are not found. | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:26
This is how they should work, but IIUC TENTATIVE f
xunjieli
2016/10/14 18:23:34
Done.
| |
81 | |
82 // If the outbound GET is not modified, then the server will generally try to | |
83 // send us SDCH encoded content. As that content returns, there are several | |
84 // corruptions of the header "content-encoding" that proxies may perform (and | |
85 // have been detected in the wild). We already dealt with the a honest | |
86 // content encoding of "sdch,gzip" being corrupted into "sdch" with on change | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:25
nit: "on" -> "no"
xunjieli
2016/10/14 18:23:34
Done.
| |
87 // of the actual content. Another common corruption is to either disscard | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:25
nit: "discard"
xunjieli
2016/10/14 18:23:34
Done.
| |
88 // the accurate content encoding, or to replace it with gzip only (again, with | |
89 // no change in actual content). The last observed corruption it to actually | |
90 // change the content, such as by re-gzipping it, and that may happen along | |
91 // with corruption of the stated content encoding (wow!). | |
92 | |
93 // The one unresolved failure mode comes when we advertise a dictionary, and | |
94 // the server tries to *send* a gzipped file (not gzip encode content), and | |
95 // then we could do a gzip decode :-(. Since SDCH is only (currently) | |
96 // supported server side on paths that only send HTML content, this mode has | |
97 // never surfaced in the wild (and is unlikely to). | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:25
Sadly, this last sentence is no longer true. I ha
xunjieli
2016/10/14 18:23:34
Done.
| |
98 // We will gather a lot of stats as we perform the fixups | |
99 if (base::StartsWith(mime_type, kTextHtml, | |
100 base::CompareCase::INSENSITIVE_ASCII)) { | |
101 // Suspicious case: Advertised dictionary, but server didn't use sdch, and | |
102 // we're HTML tagged. | |
103 if (types->empty()) { | |
104 LogSdchProblem(net_log, SDCH_ADDED_CONTENT_ENCODING); | |
105 } else if (1 == types->size()) { | |
106 LogSdchProblem(net_log, SDCH_FIXED_CONTENT_ENCODING); | |
107 } else { | |
108 LogSdchProblem(net_log, SDCH_FIXED_CONTENT_ENCODINGS); | |
109 } | |
110 } else { | |
111 // Remarkable case!?! We advertised an SDCH dictionary, content-encoding | |
112 // was not marked for SDCH processing: Why did the server suggest an SDCH | |
113 // dictionary in the first place??. Also, the content isn't | |
114 // tagged as HTML, despite the fact that SDCH encoding is mostly likely | |
115 // for HTML: Did some anti-virus system strip this tag (sometimes they | |
116 // strip accept-encoding headers on the request)?? Does the content | |
117 // encoding not start with "text/html" for some other reason?? We'll | |
118 // report this as a fixup to a binary file, but it probably really is | |
119 // text/html (some how). | |
120 if (types->empty()) { | |
121 LogSdchProblem(net_log, SDCH_BINARY_ADDED_CONTENT_ENCODING); | |
122 } else if (1 == types->size()) { | |
123 LogSdchProblem(net_log, SDCH_BINARY_FIXED_CONTENT_ENCODING); | |
124 } else { | |
125 LogSdchProblem(net_log, SDCH_BINARY_FIXED_CONTENT_ENCODINGS); | |
126 } | |
127 } | |
128 | |
129 // Leave the existing encoding type to be processed first, and add our | |
130 // tentative decodings to be done afterwards. Vodaphone UK reportedyl will | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:25
nit: "reportedly"
xunjieli
2016/10/14 18:23:34
Done.
| |
131 // perform a second layer of gzip encoding atop the server's sdch,gzip | |
132 // encoding, and then claim that the content encoding is a mere gzip. As a | |
133 // result we'll need (in that case) to do the gunzip, plus our tentative | |
134 // gunzip and tentative SDCH decoding. This approach nicely handles the | |
135 // empty() list as well, and should work with other (as yet undiscovered) | |
136 // proxies the choose to re-compressed with some other encoding (such as | |
137 // bzip2, etc.). | |
138 types->insert(types->begin(), SourceStream::TYPE_GZIP_FALLBACK); | |
139 types->insert(types->begin(), SourceStream::TYPE_SDCH_POSSIBLE); | |
140 } | |
141 | |
142 // Dictionary id errors are often the first indication that the SDCH stream has | |
143 // become corrupt. There are many possible causes: non-200 response codes, a | |
144 // cached non-SDCH-ified reply, or a response that claims to be SDCH but isn't | |
145 // actually. These are handled here by issuing a meta-refresh or swapping to the | |
146 // "passthrough" mode if appropriate, or failing the request if the error is | |
147 // unrecoverable. | |
148 SdchPolicyDelegate::ErrorRecovery SdchPolicyDelegate::OnDictionaryIdError( | |
149 bool possible_pass_through, | |
150 std::string* replace_output) { | |
151 if (possible_pass_through) { | |
152 LogCorruptionDetection(RESPONSE_TENTATIVE_SDCH); | |
153 return PASS_THROUGH; | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:26
Sadly, I think this is a change from the original
xunjieli
2016/10/14 18:23:34
Done. Ah, you are right! I didn't realize that.
| |
154 } | |
155 // HTTP 404 might be an unencoded error page, so if decoding failed, pass it | |
156 // through. TODO(xunjieli): Remove this. crbug.com/516773. | |
157 if (response_code_ == 404) { | |
158 LogSdchProblem(net_log_, SDCH_PASS_THROUGH_404_CODE); | |
159 LogCorruptionDetection(RESPONSE_404); | |
160 return PASS_THROUGH; | |
161 } | |
162 | |
163 // HTTP !200 gets a meta-refresh for HTML. | |
164 // TODO(xunjieli): remove this. crbug.com/654393. | |
165 if (response_code_ != 200) { | |
166 LogCorruptionDetection(RESPONSE_NOT_200); | |
167 return IssueMetaRefreshIfPossible(replace_output); | |
168 } | |
169 | |
170 // If this is a cached result and the source hasn't requested a dictionary, it | |
171 // probably never had a dictionary to begin and is an unencoded response from | |
172 // earlier. | |
173 if (is_cached_content_) { | |
174 LogSdchProblem(net_log_, SDCH_PASS_THROUGH_OLD_CACHED); | |
175 LogCorruptionDetection(RESPONSE_OLD_UNENCODED); | |
176 return PASS_THROUGH; | |
177 } | |
178 | |
179 // The original request didn't advertise any dictionaries, but the | |
180 // response claimed to be SDCH. There is no way to repair this situation: the | |
181 // original request already didn't advertise any dictionaries, and retrying it | |
182 // would likely have the/ same result. Blacklist the domain and try passing | |
183 // through. | |
184 if (!dictionary_set_) { | |
185 sdch_manager_->BlacklistDomain(url_, SDCH_PASSING_THROUGH_NON_SDCH); | |
186 LogCorruptionDetection(RESPONSE_ENCODING_LIE); | |
187 return PASS_THROUGH; | |
188 } | |
189 return IssueMetaRefreshIfPossible(replace_output); | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:26
Hmmm. In the old code, no matter how we left the
xunjieli
2016/10/14 18:23:34
Done.
| |
190 } | |
191 | |
192 // Dictionary fails to load when we have a plausible dictionay id. There are | |
193 // many possible causes: a cached SDCH-ified reply for which the SdchManager did | |
194 // not have the dictionary or a corrupted response. These are handled here by | |
195 // issuing a meta-refresh except the case where response code is 404. | |
196 SdchPolicyDelegate::ErrorRecovery SdchPolicyDelegate::OnGetDictionaryError( | |
197 bool possible_pass_through, | |
198 std::string* replace_output) { | |
199 if (possible_pass_through) { | |
200 LogCorruptionDetection(RESPONSE_TENTATIVE_SDCH); | |
201 return PASS_THROUGH; | |
202 } | |
203 // HTTP 404 might be an unencoded error page, so if decoding failed, pass it | |
204 // through. TODO(xunjieli): Remove this case crbug.com/516773. | |
205 if (response_code_ == 404) { | |
206 LogSdchProblem(net_log_, SDCH_PASS_THROUGH_404_CODE); | |
207 LogCorruptionDetection(RESPONSE_404); | |
208 return PASS_THROUGH; | |
209 } | |
210 return IssueMetaRefreshIfPossible(replace_output); | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:26
Much like the above, the lack of a LogCorruptionDe
xunjieli
2016/10/14 18:23:34
Done.
| |
211 } | |
212 | |
213 SdchPolicyDelegate::ErrorRecovery SdchPolicyDelegate::OnDecodingError( | |
214 std::string* replace_output) { | |
215 // A decoding error, as opposed to a dictionary error, indicates a | |
216 // decompression failure partway through the payload of the SDCH stream, | |
217 // which means that the filter already witnessed a valid dictionary ID and | |
218 // successfully retrieved a dictionary for it. Decoding errors are not | |
219 // recoverable and it is not appropriate to stop decoding, so there are | |
220 // relatively few error cases here. | |
221 // | |
222 // In particular, a decoding error for an HTML payload is recoverable by | |
223 // issuing a meta-refresh, but to avoid having that happen too often, this | |
224 // class also temporarily blacklists the domain. A decoding error for a | |
225 // non-HTML payload is unrecoverable, so such an error gets a permanent | |
226 // blacklist entry. If the content was cached, no blacklisting is needed. | |
227 // TODO(xunjieli): This case should be removed. crbug.com/651821. | |
228 return IssueMetaRefreshIfPossible(replace_output); | |
229 } | |
230 | |
231 bool SdchPolicyDelegate::OnGetDictionary(const std::string& server_id, | |
232 const std::string** text) { | |
233 if (dictionary_set_) { | |
234 *text = dictionary_set_->GetDictionaryText(server_id); | |
235 if (*text) { | |
236 server_id_ = server_id; | |
237 return true; | |
238 } | |
239 } | |
240 // This is a hack. Naively, the dictionaries available for | |
241 // decoding should be only the ones advertised. However, there are | |
242 // cases, specifically resources encoded with old dictionaries living | |
243 // in the cache, that mean the full set of dictionaries should be made | |
244 // available for decoding. It's not known how often this happens; | |
245 // if it happens rarely enough, this code can be removed. | |
246 // | |
247 // TODO(rdsmith): Long-term, a better solution is necessary, since | |
248 // an entry in the cache being encoded with the dictionary doesn't | |
249 // guarantee that the dictionary is present. That solution probably | |
250 // involves storing unencoded resources in the cache, but might | |
251 // involve evicting encoded resources on dictionary removal. | |
252 // See http://crbug.com/383405. | |
253 SdchProblemCode rv = SDCH_OK; | |
254 unexpected_dictionary_set_ = | |
255 sdch_manager_->GetDictionarySetByHash(url_, server_id, &rv); | |
256 if (unexpected_dictionary_set_) { | |
257 *text = unexpected_dictionary_set_->GetDictionaryText(server_id); | |
258 LogSdchProblem(net_log_, is_cached_content_ | |
259 ? SDCH_UNADVERTISED_DICTIONARY_USED_CACHED | |
260 : SDCH_UNADVERTISED_DICTIONARY_USED); | |
261 if (*text) { | |
262 server_id_ = server_id; | |
263 return true; | |
264 } | |
265 } else { | |
266 LogSdchProblem(net_log_, SDCH_DICTIONARY_HASH_NOT_FOUND); | |
267 LogCorruptionDetection(RESPONSE_NO_DICTIONARY); | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:25
This seems like the wrong place to log a corruptio
xunjieli
2016/10/14 18:23:34
Done.
| |
268 } | |
269 return false; | |
270 } | |
271 | |
272 void SdchPolicyDelegate::OnStreamDestroyed( | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:26
Why a separate function rather than in ~SdchPolicy
xunjieli
2016/10/14 18:23:34
I used a separate function to pass in |input_state
Randy Smith (Not in Mondays)
2016/10/19 19:49:41
Ah, good point; I should have thought of that.
xunjieli
2016/10/20 00:09:14
Done.
| |
273 SdchSourceStream::InputState input_state, | |
274 const std::string& buffered_output, | |
275 open_vcdiff::VCDiffStreamingDecoder* decoder) { | |
276 if (decoder) { | |
277 if (!decoder->FinishDecoding()) { | |
278 LogSdchProblem(net_log_, SDCH_INCOMPLETE_SDCH_CONTENT); | |
279 // Make it possible for the user to hit reload, and get non-sdch content. | |
280 // Note this will "wear off" quickly enough, and is just meant to assure | |
281 // in some rare case that the user is not stuck. | |
282 sdch_manager_->BlacklistDomain(url_, SDCH_INCOMPLETE_SDCH_CONTENT); | |
283 } | |
284 } | |
285 // Filter chaining error, or premature teardown. | |
286 if (!buffered_output.empty()) | |
287 LogSdchProblem(net_log_, SDCH_UNFLUSHED_CONTENT); | |
288 | |
289 // FIXME(xunjieli): Why do we do an early return here? | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:25
For the logging, maybe because we've already recor
xunjieli
2016/10/14 18:23:34
Done. Ah, that makes sense. I added a comment.
| |
290 if (is_cached_content_) { | |
291 // Not a real error, but it is useful to have this tally. | |
292 // TODO(jar): Remove this stat after SDCH stability is validated. | |
293 LogSdchProblem(net_log_, SDCH_CACHE_DECODED); | |
294 return; // We don't need timing stats, and we aready got ratios. | |
295 } | |
296 switch (input_state) { | |
297 case SdchSourceStream::STATE_DECODE: { | |
298 job_->RecordPacketStats(FilterContext::StatisticSelector::SDCH_DECODE); | |
299 // Allow latency experiments to proceed. | |
300 sdch_manager_->SetAllowLatencyExperiment(url_, true); | |
301 | |
302 // Notify successful dictionary usage. | |
303 DCHECK(!server_id_.empty()); | |
304 sdch_manager_->OnDictionaryUsed(server_id_); | |
305 return; | |
306 } | |
307 case SdchSourceStream::STATE_LOAD_DICTIONARY: | |
308 LogSdchProblem(net_log_, SDCH_PRIOR_TO_DICTIONARY); | |
309 return; | |
310 case SdchSourceStream::STATE_PASS_THROUGH: | |
311 job_->RecordPacketStats( | |
312 FilterContext::StatisticSelector::SDCH_PASSTHROUGH); | |
313 return; | |
314 case SdchSourceStream::STATE_OUTPUT_REPLACE: | |
315 // This is meta refresh case. Already accounted for when set. | |
316 return; | |
317 } // end of switch. | |
318 } | |
319 | |
320 // TODO(xunjieli): Remove meta refresh. crbug.com/651821. | |
321 SdchPolicyDelegate::ErrorRecovery | |
322 SdchPolicyDelegate::IssueMetaRefreshIfPossible(std::string* replace_output) { | |
323 // Errors for non-HTML payloads are unrecoverable and get the domain | |
324 // blacklisted indefinitely. | |
325 if (mime_type_.npos == mime_type_.find("text/html")) { | |
326 SdchProblemCode problem = | |
327 (is_cached_content_ ? SDCH_CACHED_META_REFRESH_UNSUPPORTED | |
328 : SDCH_META_REFRESH_UNSUPPORTED); | |
329 sdch_manager_->BlacklistDomainForever(url_, problem); | |
330 LogSdchProblem(net_log_, problem); | |
331 return NONE; | |
332 } | |
333 | |
334 if (is_cached_content_) { | |
335 // Cached content is a probably startup tab, so just get the fresh content | |
336 // and try again, without disabling SDCH. | |
337 LogSdchProblem(net_log_, SDCH_META_REFRESH_CACHED_RECOVERY); | |
338 } else { | |
339 // Since it wasn't in the cache, blacklist for some period to get the | |
340 // correct content. | |
341 sdch_manager_->BlacklistDomain(url_, SDCH_META_REFRESH_RECOVERY); | |
342 LogSdchProblem(net_log_, SDCH_META_REFRESH_RECOVERY); | |
343 } | |
344 | |
345 *replace_output = std::string(kRefreshHtml, strlen(kRefreshHtml)); | |
346 return REPLACE_OUTPUT; | |
347 } | |
348 | |
349 void SdchPolicyDelegate::LogSdchProblem(NetLogWithSource netlog, | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:26
nit: // static
xunjieli
2016/10/14 18:23:34
Done.
| |
350 SdchProblemCode problem) { | |
351 SdchManager::SdchErrorRecovery(problem); | |
352 netlog.AddEvent(NetLogEventType::SDCH_DECODING_ERROR, | |
353 base::Bind(&NetLogSdchResourceProblemCallback, problem)); | |
354 } | |
355 | |
356 void SdchPolicyDelegate::LogCorruptionDetection( | |
Randy Smith (Not in Mondays)
2016/10/13 22:05:25
Suggestion: It feels weird/inconsistent to have tw
xunjieli
2016/10/14 18:23:34
Done.
| |
357 ResponseCorruptionDetectionCause cause) { | |
358 // Use if statement rather than ?: because UMA_HISTOGRAM_ENUMERATION | |
359 // caches the histogram name based on the call site. | |
360 if (is_cached_content_) { | |
361 UMA_HISTOGRAM_ENUMERATION("Sdch3.ResponseCorruptionDetection.Cached", cause, | |
362 RESPONSE_MAX); | |
363 } else { | |
364 UMA_HISTOGRAM_ENUMERATION("Sdch3.ResponseCorruptionDetection.Uncached", | |
365 cause, RESPONSE_MAX); | |
366 } | |
367 net_log_.AddEvent(NetLogEventType::SDCH_RESPONSE_CORRUPTION_DETECTION, | |
368 base::Bind(&NetLogResponseCorruptionDetectionCallback, | |
369 cause, is_cached_content_)); | |
370 } | |
371 | |
372 // static. | |
373 const char* SdchPolicyDelegate::ResponseCorruptionDetectionCauseToString( | |
374 ResponseCorruptionDetectionCause cause) { | |
375 const char* cause_string = "<unknown>"; | |
376 switch (cause) { | |
377 case RESPONSE_NONE: | |
378 cause_string = "NONE"; | |
379 break; | |
380 case RESPONSE_404: | |
381 cause_string = "404"; | |
382 break; | |
383 case RESPONSE_NOT_200: | |
384 cause_string = "NOT_200"; | |
385 break; | |
386 case RESPONSE_OLD_UNENCODED: | |
387 cause_string = "OLD_UNENCODED"; | |
388 break; | |
389 case RESPONSE_TENTATIVE_SDCH: | |
390 cause_string = "TENTATIVE_SDCH"; | |
391 break; | |
392 case RESPONSE_NO_DICTIONARY: | |
393 cause_string = "NO_DICTIONARY"; | |
394 break; | |
395 case RESPONSE_CORRUPT_SDCH: | |
396 cause_string = "CORRUPT_SDCH"; | |
397 break; | |
398 case RESPONSE_ENCODING_LIE: | |
399 cause_string = "ENCODING_LIE"; | |
400 break; | |
401 case RESPONSE_MAX: | |
402 cause_string = "<Error: max enum value>"; | |
403 break; | |
404 } | |
405 return cause_string; | |
406 } | |
407 | |
408 // static. | |
409 std::unique_ptr<base::Value> | |
410 SdchPolicyDelegate::NetLogResponseCorruptionDetectionCallback( | |
411 ResponseCorruptionDetectionCause cause, | |
412 bool cached, | |
413 NetLogCaptureMode capture_mode) { | |
414 std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue()); | |
415 dict->SetString("cause", ResponseCorruptionDetectionCauseToString(cause)); | |
416 dict->SetBoolean("cached", cached); | |
417 return std::move(dict); | |
418 } | |
419 | |
420 } // namespace net | |
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