Bug 628197. Implement do-not-track HTTP header to express user intent to halt tracking across site. r=dwitte, a=jst.

--HG--
extra : rebase_source : 29550c73f45bfefac311cdce4eef80e947869738

modules/libpref/src/init/all.js

@@ -586,6 +586,9 @@ pref("content.sink.pending_event_mode", 0);
 //   2 = openAbused
 pref("privacy.popups.disable_from_plugins", 2);
 
+// "do not track" HTTP header, disabled by default
+pref("privacy.donottrackheader.enabled",    false);
+
 pref("dom.event.contextmenu.enabled",       true);
 
 pref("javascript.enabled",                  true);

netwerk/protocol/http/nsHttpAtomList.h

@@ -77,6 +77,7 @@ HTTP_ATOM(DAV,                       "DAV")
 HTTP_ATOM(Depth,                     "Depth")
 HTTP_ATOM(Derived_From,              "Derived-From")
 HTTP_ATOM(Destination,               "Destination")
+HTTP_ATOM(DoNotTrack,                "DNT")
 HTTP_ATOM(ETag,                      "Etag")
 HTTP_ATOM(Expect,                    "Expect")
 HTTP_ATOM(Expires,                   "Expires")

netwerk/protocol/http/nsHttpHandler.cpp

@@ -130,6 +130,7 @@ static NS_DEFINE_CID(kSocketProviderServiceCID, NS_SOCKETPROVIDERSERVICE_CID);
 #define INTL_ACCEPT_CHARSET     "intl.charset.default"
 #define NETWORK_ENABLEIDN       "network.enableIDN"
 #define BROWSER_PREF_PREFIX     "browser.cache."
+#define DONOTTRACK_HEADER_ENABLED "privacy.donottrackheader.enabled"
 
 #define UA_PREF(_pref) UA_PREF_PREFIX _pref
 #define HTTP_PREF(_pref) HTTP_PREF_PREFIX _pref
@@ -198,6 +199,7 @@ nsHttpHandler::nsHttpHandler()
     , mPromptTempRedirect(PR_TRUE)
     , mSendSecureXSiteReferrer(PR_TRUE)
     , mEnablePersistentHttpsCaching(PR_FALSE)
+    , mDoNotTrackEnabled(PR_FALSE)
 {
 #if defined(PR_LOGGING)
     gHttpLog = PR_NewLogModule("nsHttp");
@@ -262,6 +264,7 @@ nsHttpHandler::Init()
         prefBranch->AddObserver(INTL_ACCEPT_CHARSET, this, PR_TRUE);
         prefBranch->AddObserver(NETWORK_ENABLEIDN, this, PR_TRUE);
         prefBranch->AddObserver(BROWSER_PREF("disk_cache_ssl"), this, PR_TRUE);
+        prefBranch->AddObserver(DONOTTRACK_HEADER_ENABLED, this, PR_TRUE);
 
         PrefsChanged(prefBranch, nsnull);
     }
@@ -406,6 +409,13 @@ nsHttpHandler::AddStandardRequestHeaders(nsHttpHeaderArray *request,
         request->SetHeader(nsHttp::Connection, close);
     }
 
+    // Add the "Do-Not-Track" header
+    if (mDoNotTrackEnabled) {
+      rv = request->SetHeader(nsHttp::DoNotTrack,
+                              NS_LITERAL_CSTRING("1"));
+      if (NS_FAILED(rv)) return rv;
+    }
+
     const nsHttpAtom &header = useProxy ? nsHttp::Proxy_Connection
                                         : nsHttp::Connection;
     return request->SetHeader(header, *connectionType);
@@ -1126,6 +1136,18 @@ nsHttpHandler::PrefsChanged(nsIPrefBranch *prefs, const char *pref)
             mIDNConverter = nsnull;
     }
 
+    //
+    // Tracking options
+    //
+
+    if (PREF_CHANGED(DONOTTRACK_HEADER_ENABLED)) {
+        cVar = PR_FALSE;
+        rv = prefs->GetBoolPref(DONOTTRACK_HEADER_ENABLED, &cVar);
+        if (NS_SUCCEEDED(rv)) {
+            mDoNotTrackEnabled = cVar;
+        }
+    }
+
 #undef PREF_CHANGED
 #undef MULTI_PREF_CHANGED
 }

netwerk/protocol/http/nsHttpHandler.h

@@ -326,6 +326,9 @@ private:
 
     // Persistent HTTPS caching flag
     PRPackedBool   mEnablePersistentHttpsCaching;
+
+    // For broadcasting the preference to not be tracked
+    PRPackedBool   mDoNotTrackEnabled;
 };
 
 //-----------------------------------------------------------------------------