Sdch view for net-internals

net/base/sdch_manager.h

 // Copyright (c) 2011 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.
 
 #ifndef NET_BASE_SDCH_MANAGER_H_
 #define NET_BASE_SDCH_MANAGER_H_
 
 #include <map>
 #include <set>
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "net/base/net_export.h"
+#include "net/base/sdch_problem_codes.h"
 #include "url/gurl.h"
 
+namespace base {
+class Value;
+}
+
 namespace net {
 
 class SdchObserver;
 
 // Provides global database of differential decompression dictionaries for the
 // SDCH filter (processes sdch enconded content).
 //
 // The SdchManager maintains a collection of memory resident dictionaries. It
 // can find a dictionary (based on a server specification of a hash), store a
 // dictionary, and make judgements about what URLs can use, set, etc. a
 // dictionary.
 
 // These dictionaries are acquired over the net, and include a header
 // (containing metadata) as well as a VCDIFF dictionary (for use by a VCDIFF
 // module) to decompress data.
 class NET_EXPORT SdchManager {
  public:
-  // A list of errors that appeared and were either resolved, or used to turn
-  // off sdch encoding.
-  enum ProblemCodes {
-    MIN_PROBLEM_CODE,
-
-    // Content-encoding correction problems.
-    ADDED_CONTENT_ENCODING = 1,
-    FIXED_CONTENT_ENCODING = 2,
-    FIXED_CONTENT_ENCODINGS = 3,
-
-    // Content decoding errors.
-    DECODE_HEADER_ERROR = 4,
-    DECODE_BODY_ERROR = 5,
-
-    // More content-encoding correction problems.
-    OPTIONAL_GUNZIP_ENCODING_ADDED = 6,
-
-    // Content encoding correction when we're not even tagged as HTML!?!
-    BINARY_ADDED_CONTENT_ENCODING = 7,
-    BINARY_FIXED_CONTENT_ENCODING = 8,
-    BINARY_FIXED_CONTENT_ENCODINGS = 9,
-
-    // Dictionary selection for use problems.
-    DICTIONARY_FOUND_HAS_WRONG_DOMAIN = 10,
-    DICTIONARY_FOUND_HAS_WRONG_PORT_LIST = 11,
-    DICTIONARY_FOUND_HAS_WRONG_PATH = 12,
-    DICTIONARY_FOUND_HAS_WRONG_SCHEME = 13,
-    DICTIONARY_HASH_NOT_FOUND = 14,
-    DICTIONARY_HASH_MALFORMED = 15,
-
-    // Dictionary saving problems.
-    DICTIONARY_HAS_NO_HEADER = 20,
-    DICTIONARY_HEADER_LINE_MISSING_COLON = 21,
-    DICTIONARY_MISSING_DOMAIN_SPECIFIER = 22,
-    DICTIONARY_SPECIFIES_TOP_LEVEL_DOMAIN = 23,
-    DICTIONARY_DOMAIN_NOT_MATCHING_SOURCE_URL = 24,
-    DICTIONARY_PORT_NOT_MATCHING_SOURCE_URL = 25,
-    DICTIONARY_HAS_NO_TEXT = 26,
-    DICTIONARY_REFERER_URL_HAS_DOT_IN_PREFIX = 27,
-
-    // Dictionary loading problems.
-    DICTIONARY_LOAD_ATTEMPT_FROM_DIFFERENT_HOST = 30,
-    DICTIONARY_SELECTED_FOR_SSL = 31,
-    DICTIONARY_ALREADY_LOADED = 32,
-    DICTIONARY_SELECTED_FROM_NON_HTTP = 33,
-    DICTIONARY_IS_TOO_LARGE= 34,
-    DICTIONARY_COUNT_EXCEEDED = 35,
-    DICTIONARY_ALREADY_SCHEDULED_TO_DOWNLOAD = 36,
-    DICTIONARY_ALREADY_TRIED_TO_DOWNLOAD = 37,
-    DICTIONARY_FETCH_READ_FAILED = 38,
-
-    // Failsafe hack.
-    ATTEMPT_TO_DECODE_NON_HTTP_DATA = 40,
-
-
-    // Content-Encoding problems detected, with no action taken.
-    MULTIENCODING_FOR_NON_SDCH_REQUEST = 50,
-    SDCH_CONTENT_ENCODE_FOR_NON_SDCH_REQUEST = 51,
-
-    // Dictionary manager issues.
-    DOMAIN_BLACKLIST_INCLUDES_TARGET = 61,
-
-    // Problematic decode recovery methods.
-    META_REFRESH_RECOVERY = 70,            // Dictionary not found.
-    // defunct =  71, // Almost the same as META_REFRESH_UNSUPPORTED.
-    // defunct = 72,  // Almost the same as CACHED_META_REFRESH_UNSUPPORTED.
-    // defunct = 73,  // PASSING_THROUGH_NON_SDCH plus
-                      // RESPONSE_TENTATIVE_SDCH in ../filter/sdch_filter.cc.
-    META_REFRESH_UNSUPPORTED = 74,         // Unrecoverable error.
-    CACHED_META_REFRESH_UNSUPPORTED = 75,  // As above, but pulled from cache.
-    PASSING_THROUGH_NON_SDCH = 76,  // Tagged sdch but missing dictionary-hash.
-    INCOMPLETE_SDCH_CONTENT = 77,   // Last window was not completely decoded.
-    PASS_THROUGH_404_CODE = 78,     // URL not found message passing through.
-
-    // This next report is very common, and not really an error scenario, but
-    // it exercises the error recovery logic.
-    PASS_THROUGH_OLD_CACHED = 79,   // Back button got pre-SDCH cached content.
-
-    // Common decoded recovery methods.
-    META_REFRESH_CACHED_RECOVERY = 80,  // Probably startup tab loading.
-    // defunct = 81, // Now tracked by ResponseCorruptionDetectionCause histo.
-
-    // Non SDCH problems, only accounted for to make stat counting complete
-    // (i.e., be able to be sure all dictionary advertisements are accounted
-    // for).
-
-    UNFLUSHED_CONTENT = 90,    // Possible error in filter chaining.
-    // defunct = 91,           // MISSING_TIME_STATS (Should never happen.)
-    CACHE_DECODED = 92,        // No timing stats recorded.
-    // defunct = 93,           // OVER_10_MINUTES (No timing stats recorded.)
-    UNINITIALIZED = 94,        // Filter never even got initialized.
-    PRIOR_TO_DICTIONARY = 95,  // We hadn't even parsed a dictionary selector.
-    DECODE_ERROR = 96,         // Something went wrong during decode.
-
-    // Problem during the latency test.
-    LATENCY_TEST_DISALLOWED = 100,  // SDCH now failing, but it worked before!
-
-    MAX_PROBLEM_CODE  // Used to bound histogram.
-  };
-
   // Use the following static limits to block DOS attacks until we implement
   // a cached dictionary evicition strategy.
   static const size_t kMaxDictionarySize;
   static const size_t kMaxDictionaryCount;
 
   // There is one instance of |Dictionary| for each memory-cached SDCH
   // dictionary.
   class NET_EXPORT_PRIVATE Dictionary : public base::RefCounted<Dictionary> {
    public:
     // Sdch filters can get our text to use in decoding compressed data.
@@ skipping 12 matching lines @@
                const std::string& client_hash,
                const GURL& url,
                const std::string& domain,
                const std::string& path,
                const base::Time& expiration,
                const std::set<int>& ports);
     virtual ~Dictionary();
 
     const GURL& url() const { return url_; }
     const std::string& client_hash() const { return client_hash_; }
+    const std::string& domain() const { return domain_; }
+    const std::string& path() const { return path_; }
+    const base::Time& expiration() const { return expiration_; }
+    const std::set<int>& ports() const { return ports_; }
 
     // Security method to check if we can advertise this dictionary for use
     // if the |target_url| returns SDCH compressed data.
-    bool CanAdvertise(const GURL& target_url);
+    SdchProblemCode CanAdvertise(const GURL& target_url) const;
 
     // Security methods to check if we can establish a new dictionary with the
     // given data, that arrived in response to get of dictionary_url.
-    static bool CanSet(const std::string& domain, const std::string& path,
-                       const std::set<int>& ports, const GURL& dictionary_url);
+    static SdchProblemCode CanSet(const std::string& domain,
+                                  const std::string& path,
+                                  const std::set<int>& ports,
+                                  const GURL& dictionary_url);
 
     // Security method to check if we can use a dictionary to decompress a
     // target that arrived with a reference to this dictionary.
-    bool CanUse(const GURL& referring_url);
+    SdchProblemCode CanUse(const GURL& referring_url) const;
 
     // Compare paths to see if they "match" for dictionary use.
     static bool PathMatch(const std::string& path,
                           const std::string& restriction);
 
     // Compare domains to see if the "match" for dictionary use.
     static bool DomainMatch(const GURL& url, const std::string& restriction);
 
-
     // The actual text of the dictionary.
     std::string text_;
 
     // Part of the hash of text_ that the client uses to advertise the fact that
     // it has a specific dictionary pre-cached.
     std::string client_hash_;
 
     // The GURL that arrived with the text_ in a URL request to specify where
     // this dictionary may be used.
     const GURL url_;
 
     // Metadate "headers" in before dictionary text contained the following:
     // Each dictionary payload consists of several headers, followed by the text
     // of the dictionary. The following are the known headers.
     const std::string domain_;
     const std::string path_;
     const base::Time expiration_;  // Implied by max-age.
     const std::set<int> ports_;
 
     DISALLOW_COPY_AND_ASSIGN(Dictionary);
   };
 
   SdchManager();
   ~SdchManager();
 
   // Clear data (for browser data removal).
   void ClearData();
 
   // Record stats on various errors.
-  static void SdchErrorRecovery(ProblemCodes problem);
+  static void SdchErrorRecovery(SdchProblemCode problem);
 
   // Enables or disables SDCH compression.
   static void EnableSdchSupport(bool enabled);
 
   static bool sdch_enabled() { return g_sdch_enabled_; }
 
   // Enables or disables SDCH compression over secure connection.
   static void EnableSecureSchemeSupport(bool enabled);
 
   static bool secure_scheme_supported() { return g_secure_scheme_supported_; }
 
   // Briefly prevent further advertising of SDCH on this domain (if SDCH is
   // enabled). After enough calls to IsInSupportedDomain() the blacklisting
   // will be removed. Additional blacklists take exponentially more calls
   // to IsInSupportedDomain() before the blacklisting is undone.
   // Used when filter errors are found from a given domain, but it is plausible
   // that the cause is temporary (such as application startup, where cached
   // entries are used, but a dictionary is not yet loaded).
-  void BlacklistDomain(const GURL& url, ProblemCodes blacklist_reason);
+  void BlacklistDomain(const GURL& url, SdchProblemCode blacklist_reason);
 
   // Used when SEVERE filter errors are found from a given domain, to prevent
   // further use of SDCH on that domain.
-  void BlacklistDomainForever(const GURL& url, ProblemCodes blacklist_reason);
+  void BlacklistDomainForever(const GURL& url,
+                              SdchProblemCode blacklist_reason);
 
   // Unit test only, this function resets enabling of sdch, and clears the
   // blacklist.
   void ClearBlacklistings();
 
   // Unit test only, this function resets the blacklisting count for a domain.
   void ClearDomainBlacklisting(const std::string& domain);
 
   // Unit test only: indicate how many more times a domain will be blacklisted.
   int BlackListDomainCount(const std::string& domain);
 
   // Unit test only: Indicate what current blacklist increment is for a domain.
   int BlacklistDomainExponential(const std::string& domain);
 
   // Check to see if SDCH is enabled (globally), and the given URL is in a
   // supported domain (i.e., not blacklisted, and either the specific supported
   // domain, or all domains were assumed supported). If it is blacklist, reduce
   // by 1 the number of times it will be reported as blacklisted.
-  bool IsInSupportedDomain(const GURL& url);
+  SdchProblemCode IsInSupportedDomain(const GURL& url);
 
   // Send out appropriate events notifying observers that a Get-Dictionary
   // header has been seen.
-  void OnGetDictionary(const GURL& request_url, const GURL& dictionary_url);
+  SdchProblemCode OnGetDictionary(const GURL& request_url,
+                                  const GURL& dictionary_url);
 
   // Find the vcdiff dictionary (the body of the sdch dictionary that appears
   // after the meta-data headers like Domain:...) with the given |server_hash|
   // to use to decompreses data that arrived as SDCH encoded content. Check to
   // be sure the returned |dictionary| can be used for decoding content supplied
   // in response to a request for |referring_url|.
   // Return null in |dictionary| if there is no matching legal dictionary.
-  void GetVcdiffDictionary(const std::string& server_hash,
-                           const GURL& referring_url,
-                           scoped_refptr<Dictionary>* dictionary);
+  // Returns SDCH_OK if dictionary is not found, SDCH(-over-https) is disabled,
+  // or if matching legal dictionary exists. Otherwise returns the
+  // corresponding problem code.
+  SdchProblemCode GetVcdiffDictionary(const std::string& server_hash,
+                                      const GURL& referring_url,
+                                      scoped_refptr<Dictionary>* dictionary);
 
   // Get list of available (pre-cached) dictionaries that we have already loaded
   // into memory. The list is a comma separated list of (client) hashes per
   // the SDCH spec.
   void GetAvailDictionaryList(const GURL& target_url, std::string* list);
 
   // Construct the pair of hashes for client and server to identify an SDCH
   // dictionary. This is only made public to facilitate unit testing, but is
   // otherwise private
   static void GenerateHash(const std::string& dictionary_text,
                            std::string* client_hash, std::string* server_hash);
 
   // For Latency testing only, we need to know if we've succeeded in doing a
   // round trip before starting our comparative tests. If ever we encounter
   // problems with SDCH, we opt-out of the test unless/until we perform a
   // complete SDCH decoding.
   bool AllowLatencyExperiment(const GURL& url) const;
 
   void SetAllowLatencyExperiment(const GURL& url, bool enable);
 
+  base::Value* SdchInfoToValue() const;
+
   // Add an SDCH dictionary to our list of availible
   // dictionaries. This addition will fail if addition is illegal
   // (data in the dictionary is not acceptable from the
   // dictionary_url; dictionary already added, etc.).
-  void AddSdchDictionary(const std::string& dictionary_text,
-                         const GURL& dictionary_url);
+  // Returns SDCH_OK if the addition was successfull, and corresponding error
+  // code otherwise.
+  SdchProblemCode AddSdchDictionary(const std::string& dictionary_text,
+                                    const GURL& dictionary_url);
 
   // Registration for events generated by the SDCH subsystem.
   void AddObserver(SdchObserver* observer);
   void RemoveObserver(SdchObserver* observer);
 
  private:
   struct BlacklistInfo {
-    BlacklistInfo()
-        : count(0),
-          exponential_count(0),
-          reason(MIN_PROBLEM_CODE) {}
+    BlacklistInfo() : count(0), exponential_count(0), reason(SDCH_OK) {}
 
-    int count;                   // # of times to refuse SDCH advertisement.
-    int exponential_count;       // Current exponential backoff ratchet.
-    ProblemCodes reason;         // Why domain was blacklisted.
-
+    int count;               // # of times to refuse SDCH advertisement.
+    int exponential_count;   // Current exponential backoff ratchet.
+    SdchProblemCode reason;  // Why domain was blacklisted.
   };
   typedef std::map<std::string, BlacklistInfo> DomainBlacklistInfo;
   typedef std::set<std::string> ExperimentSet;
 
   // Determines whether a "Get-Dictionary" header is legal (dictionary
   // url has appropriate relationship to referrer url) in the SDCH
-  // protocol.  Return true if fetch is legal.
-  bool CanFetchDictionary(const GURL& referring_url,
-                          const GURL& dictionary_url) const;
+  // protocol.  Return SDCH_OK if fetch is legal.
+  SdchProblemCode CanFetchDictionary(const GURL& referring_url,
+                                     const GURL& dictionary_url) const;
 
   // A map of dictionaries info indexed by the hash that the server provides.
   typedef std::map<std::string, scoped_refptr<Dictionary> > DictionaryMap;
 
   // Support SDCH compression, by advertising in headers.
   static bool g_sdch_enabled_;
 
   // Support SDCH compression for HTTPS requests and responses. When supported,
   // HTTPS applicable dictionaries MUST have been acquired securely via HTTPS.
   static bool g_secure_scheme_supported_;
 
   // A simple implementation of a RFC 3548 "URL safe" base64 encoder.
   static void UrlSafeBase64Encode(const std::string& input,
                                   std::string* output);
+
   DictionaryMap dictionaries_;
 
   // List domains where decode failures have required disabling sdch.
   DomainBlacklistInfo blacklisted_domains_;
 
   // List of hostnames for which a latency experiment is allowed (because a
   // round trip test has recently passed).
   ExperimentSet allow_latency_experiment_;
 
   // Observers that want to be notified of SDCH events.
   // Assert list is empty on destruction since if there is an observer
   // that hasn't removed itself from the list, that observer probably
   // has a reference to the SdchManager.
   ObserverList<SdchObserver, true> observers_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(SdchManager);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_SDCH_MANAGER_H_