Avoid plausible DOS attack by malicious SDCH server

Restrict SDCH to ONLY work with HTTP (fail safe security policy for this
experimental protocol).

Also add a histogram to see how often we encounter dictionary corruption
(which will evidence itself by having a multitude of dicitionaries
adverttised, with no real use server side).

r=ajenjo,kmixter

Review URL: http://codereview.chromium.org/11209

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@5628 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 17 insertions, 0 deletions

diff --git a/net/base/sdch_manager.h b/net/base/sdch_manager.h
index 69055f1..3a8158406 100644
--- a/net/base/sdch_manager.h
+++ b/net/base/sdch_manager.h
@@ -85,15 +85,27 @@ class SdchManager {
     DICTIONARY_SPECIFIES_TOP_LEVEL_DOMAIN,
     DICTIONARY_DOMAIN_NOT_MATCHING_SOURCE_URL,
     DICTIONARY_PORT_NOT_MATCHING_SOURCE_URL,
+    DICTIONARY_HAS_NO_TEXT,
 
     // Dictionary loading problems.
     DICTIONARY_LOAD_ATTEMPT_FROM_DIFFERENT_HOST = 30,
     DICTIONARY_SELECTED_FOR_SSL,
     DICTIONARY_ALREADY_LOADED,
+    DICTIONARY_SELECTED_FROM_NON_HTTP,
+    DICTIONARY_IS_TOO_LARGE,
+    DICTIONARY_COUNT_EXCEEDED,
+
+    // Failsafe hack.
+    ATTEMPT_TO_DECODE_NON_HTTP_DATA = 40,
 
     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 Dictionary : public base::RefCounted<Dictionary> {
@@ -197,6 +209,11 @@ class SdchManager {
   // cached in memory.
   void FetchDictionary(const GURL& referring_url, const GURL& dictionary_url);
 
+  // Security test function used before initiating a fetch.
+  // Return true if fetch is legal.
+  bool CanFetchDictionary(const GURL& referring_url,
+                          const GURL& dictionary_url) const;
+
   // Add an SDCH dictionary to our list of availible dictionaries. This addition
   // will fail (return false) if addition is illegal (data in the dictionary is
   // not acceptable from the dictionary_url; dictionary already added, etc.).