Issue 5283 - Add support for $websocket and $webrtc

lib/abp2blocklist.js

Index: lib/abp2blocklist.js
===================================================================
--- a/lib/abp2blocklist.js
+++ b/lib/abp2blocklist.js
@@ -28,16 +28,18 @@
                                    | typeMap.STYLESHEET
                                    | typeMap.SCRIPT
                                    | typeMap.FONT
                                    | typeMap.MEDIA
                                    | typeMap.POPUP
                                    | typeMap.OBJECT
                                    | typeMap.OBJECT_SUBREQUEST
                                    | typeMap.XMLHTTPREQUEST
+                                   | typeMap.WEBSOCKET
+                                   | typeMap.WEBRTC
                                    | typeMap.PING
                                    | typeMap.SUBDOCUMENT
                                    | typeMap.OTHER);
 
 function parseDomains(domains, included, excluded)
 {
   for (let domain in domains)
   {
@@ -59,16 +61,41 @@
   return s.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
 }
 
 function matchDomain(domain)
 {
   return "^https?://([^/:]*\\.)?" + escapeRegExp(domain).toLowerCase() + "[/:]";
 }
 
+function getURLSchemes(contentType)
+{
+  // If the given content type includes all supported URL schemes, simply
+  // return a single generic URL scheme pattern. This minimizes the size of the
+  // generated rule set. The downside to this is that it will also match
+  // schemes that we do not want to match (e.g. "ftp://"), but this can be
+  // mitigated by adding exceptions for those schemes.
+  if (contentType & typeMap.WEBSOCKET && contentType & typeMap.WEBRTC &&
+      contentType & ~(typeMap.WEBSOCKET | typeMap.WEBRTC))
+    return ["[^:]+:(//)?"];
+
+  let urlSchemes = [];
+
+  if (contentType & typeMap.WEBSOCKET)
+    urlSchemes.push("wss?://");
+
+  if (contentType & typeMap.WEBRTC)
+    urlSchemes.push("stuns?:", "turns?:");
+
+  if (contentType & ~(typeMap.WEBSOCKET | typeMap.WEBRTC))
+    urlSchemes.push("https?://");
+
+  return urlSchemes;
+}
+
 function findSubdomainsInList(domain, list)
 {
   let subdomains = [];
   let suffixLength = domain.length + 1;
 
   for (let name of list)
   {
     if (name.length > suffixLength && name.slice(-suffixLength) == "." + domain)
@@ -104,26 +131,27 @@
 
 /**
  * Parse the given filter "regexpSource" string. Producing a regular expression,
  * extracting the hostname (if any), deciding if the regular expression is safe
  * to be converted + matched as lower case and noting if the source contains
  * anything after the hostname.)
  *
  * @param   {string} text regexpSource property of a filter
+ * @param   {string} urlScheme The URL scheme to use in the regular expression
  * @returns {object} An object containing a regular expression string, a bool
  *                   indicating if the filter can be safely matched as lower
  *                   case, a hostname string (or undefined) and a bool
  *                   indicating if the source only contains a hostname or not:
  *                     {regexp: "...",
  *                      canSafelyMatchAsLowercase: true/false,
  *                      hostname: "...",
  *                      justHostname: true/false}
  */
-function parseFilterRegexpSource(text)
+function parseFilterRegexpSource(text, urlScheme)
 {
   let regexp = [];
 
   // Convert the text into an array of Unicode characters.
   //
   // In the case of surrogate pairs (the smiley emoji, for example), one
   // Unicode code point is represented by two JavaScript characters together.
   // We want to iterate over Unicode code points rather than JavaScript
@@ -132,16 +160,19 @@
 
   let lastIndex = characters.length - 1;
   let hostname;
   let hostnameStart = null;
   let hostnameFinished = false;
   let justHostname = false;
   let canSafelyMatchAsLowercase = false;
 
+  if (!urlScheme)
+    urlScheme = getURLSchemes()[0];
+
   for (let i = 0; i < characters.length; i++)
   {
     let c = characters[i];
 
     if (hostnameFinished)
       justHostname = false;
 
     // If we're currently inside the hostname we have to be careful not to
@@ -180,17 +211,17 @@
         if (!justHostname)
           alphabet = "A-Z" + alphabet;
         let digits = "0-9";
         // Note that the "-" must appear first here in order to retain its
         // literal meaning within the brackets.
         let specialCharacters = "-_.%";
         let separator = "[^" + specialCharacters + alphabet + digits + "]";
         if (i == 0)
-          regexp.push("^https?://(.*" + separator + ")?");
+          regexp.push("^" + urlScheme + "(.*" + separator + ")?");
         else if (i == lastIndex)
           regexp.push("(" + separator + ".*)?$");
         else
           regexp.push(separator);
         break;
       case "|":
         if (i == 0)
         {
@@ -201,17 +232,17 @@
         {
           regexp.push("$");
           break;
         }
         if (i == 1 && characters[0] == "|")
         {
           hostnameStart = i + 1;
           canSafelyMatchAsLowercase = true;
-          regexp.push("https?://([^/]+\\.)?");
+          regexp.push(urlScheme + "([^/]+\\.)?");
           break;
         }
         regexp.push("\\|");
         break;
       case "/":
         if (!hostnameFinished &&
             characters[i - 2] == ":" && characters[i - 1] == "/")
         {
@@ -236,72 +267,177 @@
   return {
     regexp: regexp.join(""),
     canSafelyMatchAsLowercase: canSafelyMatchAsLowercase,
     hostname: hostname,
     justHostname: justHostname
   };
 }
 
-function getResourceTypes(filter)
+function getResourceTypes(contentType)
 {
   let types = [];
 
-  if (filter.contentType & typeMap.IMAGE)
+  if (contentType & typeMap.IMAGE)
     types.push("image");
-  if (filter.contentType & typeMap.STYLESHEET)
+  if (contentType & typeMap.STYLESHEET)
     types.push("style-sheet");
-  if (filter.contentType & typeMap.SCRIPT)
+  if (contentType & typeMap.SCRIPT)
     types.push("script");
-  if (filter.contentType & typeMap.FONT)
+  if (contentType & typeMap.FONT)
     types.push("font");
-  if (filter.contentType & (typeMap.MEDIA | typeMap.OBJECT))
+  if (contentType & (typeMap.MEDIA | typeMap.OBJECT))
     types.push("media");
-  if (filter.contentType & typeMap.POPUP)
+  if (contentType & typeMap.POPUP)
     types.push("popup");
-  if (filter.contentType & (typeMap.XMLHTTPREQUEST |
-                            typeMap.OBJECT_SUBREQUEST |
-                            typeMap.PING |
-                            typeMap.OTHER))
+  if (contentType & (typeMap.XMLHTTPREQUEST |
+                     typeMap.WEBSOCKET |
+                     typeMap.WEBRTC |
+                     typeMap.OBJECT_SUBREQUEST |
+                     typeMap.PING |
+                     typeMap.OTHER))
+  {
     types.push("raw");
-  if (filter.contentType & typeMap.SUBDOCUMENT)
+  }
+  if (contentType & typeMap.SUBDOCUMENT)
     types.push("document");
 
   return types;
 }
 
+function makeRuleCopies(trigger, action, urlSchemes)
+{
+  let copies = [];
+
+  // Always make a deep copy of the rule, since rules may have to be
+  // manipulated individually at a later stage.
+  let stringifiedTrigger = JSON.stringify(trigger);
+
+  let filterPattern = trigger["url-filter"].substring(1);
+  let startIndex = 0;
+
+  // If the URL filter already begins with the first URL scheme pattern, skip
+  // it.
+  if (trigger["url-filter"].startsWith("^" + urlSchemes[0]))
+  {
+    filterPattern = filterPattern.substring(urlSchemes[0].length);
+    startIndex = 1;
+  }
+  else
+  {
+    filterPattern = ".*" + filterPattern;
+  }
+
+  for (let i = startIndex; i < urlSchemes.length; i++)
+  {
+    let copyTrigger = Object.assign(JSON.parse(stringifiedTrigger), {
+      "url-filter": "^" + urlSchemes[i] + filterPattern
+    });
+    copies.push({trigger: copyTrigger, action});
+  }
+
+  return copies;
+}
+
+function excludeTopURLFromTrigger(trigger)
+{
+  trigger["unless-top-url"] = [trigger["url-filter"]];
+  if (trigger["url-filter-is-case-sensitive"])
+    trigger["top-url-filter-is-case-sensitive"] = true;
+}
+
 function convertFilterAddRules(rules, filter, action, withResourceTypes,
-                               exceptionDomains)
+                               exceptionDomains, contentType)
 {
-  let parsed = parseFilterRegexpSource(filter.regexpSource);
+  if (!contentType)
+    contentType = filter.contentType;
+
+  // If WebSocket or WebRTC are given along with other options but not
+  // including all three of WebSocket, WebRTC, and XMLHttpRequest, we must
+  // generate multiple rules. For example, for the filter
+  // "foo$websocket,image", we must generate one rule with "^wss?://" and "raw"
+  // and another rule with "^https?://" and "image". If we merge the two, we
+  // end up blocking requests of type XMLHttpRequest inadvertently.
+  if ((contentType & typeMap.WEBSOCKET && contentType != typeMap.WEBSOCKET &&
+       !(contentType & typeMap.WEBRTC &&
+         contentType & typeMap.XMLHTTPREQUEST)) ||
+      (contentType & typeMap.WEBRTC && contentType != typeMap.WEBRTC &&
+       !(contentType & typeMap.WEBSOCKET &&
+         contentType & typeMap.XMLHTTPREQUEST)))
+  {
+    if (contentType & typeMap.WEBSOCKET)
+    {
+      convertFilterAddRules(rules, filter, action, withResourceTypes,
+                            exceptionDomains, typeMap.WEBSOCKET);
+    }
+
+    if (contentType & typeMap.WEBRTC)
+    {
+      convertFilterAddRules(rules, filter, action, withResourceTypes,
+                            exceptionDomains, typeMap.WEBRTC);
+    }
+
+    contentType &= ~(typeMap.WEBSOCKET | typeMap.WEBRTC);
+
+    if (!contentType)
+      return;
+  }
+
+  let urlSchemes = getURLSchemes(contentType);
+  let parsed = parseFilterRegexpSource(filter.regexpSource, urlSchemes[0]);
 
   // For the special case of $document whitelisting filters with just a domain
   // we can generate an equivalent blocking rule exception using if-domain.
   if (filter instanceof filterClasses.WhitelistFilter &&
-      filter.contentType & typeMap.DOCUMENT &&
+      contentType & typeMap.DOCUMENT &&
       parsed.justHostname)
   {
     rules.push({
       trigger: {
         "url-filter": ".*",
         "if-domain": ["*" + parsed.hostname]
       },
       action: {type: "ignore-previous-rules"}
     });
     // If the filter contains other supported options we'll need to generate
     // further rules for it, but if not we can simply return now.
-    if (!(filter.contentType & whitelistableRequestTypes))
+    if (!(contentType & whitelistableRequestTypes))
       return;
   }
 
   let trigger = {"url-filter": parsed.regexp};
 
-  // Limit rules to HTTP(S) URLs
-  if (!/^(\^|http)/i.test(trigger["url-filter"]))
-    trigger["url-filter"] = "^https?://.*" + trigger["url-filter"];
+  // If the URL filter begins with one of the URL schemes for this content
+  // type, we generate additional rules for all the URL scheme patterns;
+  // otherwise, if the start of the URL filter literally matches the first URL
+  // scheme pattern, we just generate additional rules for the remaining URL
+  // scheme patterns.
+  //
+  // For example, "stun:foo$webrtc" will give us "stun:foo", then we add a "^"
+  // in front of this and generate two additional rules for
+  // "^stuns?:.*stun:foo" and "^turns?:.*stun:foo". On the other hand,
+  // "||foo$webrtc" will give us "^stuns?:([^/]+\\.)?foo", so we just generate
+  // "^turns?:([^/]+\\.)?foo" in addition.
+  //
+  // Note that the filter can be already anchored to the beginning
+  // (e.g. "|stun:foo$webrtc"), in which case we do not generate any additional
+  // rules.
+  let needAltRules = trigger["url-filter"][0] != "^" ||
+                     trigger["url-filter"].startsWith("^" + urlSchemes[0]);
+
+  if (trigger["url-filter"][0] != "^")
+  {
+    if (!urlSchemes.some(scheme => new RegExp("^" + scheme)
+                                   .test(trigger["url-filter"])))
+    {
+      trigger["url-filter"] = urlSchemes[0] + ".*" + trigger["url-filter"];
+    }
+
+    trigger["url-filter"] = "^" + trigger["url-filter"];
+  }
 
   // For rules containing only a hostname we know that we're matching against
   // a lowercase string unless the matchCase option was passed.
   if (parsed.canSafelyMatchAsLowercase && !filter.matchCase)
     trigger["url-filter"] = trigger["url-filter"].toLowerCase();
 
   if (parsed.canSafelyMatchAsLowercase || filter.matchCase)
     trigger["url-filter-is-case-sensitive"] = true;
@@ -311,17 +447,17 @@
 
   parseDomains(filter.domains, included, excluded);
 
   if (exceptionDomains)
     excluded = excluded.concat(exceptionDomains);
 
   if (withResourceTypes)
   {
-    let resourceTypes = getResourceTypes(filter);
+    let resourceTypes = getResourceTypes(contentType);
 
     // Content blocker rules can't differentiate between sub-document requests
     // (iframes) and top-level document requests. To avoid too many false
     // positives, we prevent rules with no hostname part from blocking document
     // requests.
     //
     // Once Safari 11 becomes our minimum supported version, we could change
     // our approach here to use the new "unless-top-url" property instead.
@@ -332,16 +468,18 @@
       return;
 
     trigger["resource-type"] = resourceTypes;
   }
 
   if (filter.thirdParty != null)
     trigger["load-type"] = [filter.thirdParty ? "third-party" : "first-party"];
 
+  let addTopLevelException = false;
+
   if (included.length > 0)
   {
     trigger["if-domain"] = [];
 
     for (let name of included)
     {
       // If this is a blocking filter or an element hiding filter, add the
       // subdomain wildcard only if no subdomains have been excluded.
@@ -371,22 +509,33 @@
   {
     // Rules with a hostname part are still allowed to block document requests,
     // but we add an exception for top-level documents.
     //
     // Note that we can only do this if there's no "unless-domain" property for
     // now. This also only works in Safari 11 onwards, while older versions
     // simply ignore this property. Once Safari 11 becomes our minimum
     // supported version, we can merge "unless-domain" into "unless-top-url".
-    trigger["unless-top-url"] = [trigger["url-filter"]];
-    if (trigger["url-filter-is-case-sensitive"])
-      trigger["top-url-filter-is-case-sensitive"] = true;
+    addTopLevelException = true;
+    excludeTopURLFromTrigger(trigger);
   }
 
   rules.push({trigger: trigger, action: {type: action}});
+
+  if (needAltRules)
+  {
+    // Generate additional rules for any alternative URL schemes.
+    for (let altRule of makeRuleCopies(trigger, {type: action}, urlSchemes))
+    {
+      if (addTopLevelException)
+        excludeTopURLFromTrigger(altRule.trigger);
+
+      rules.push(altRule);
+    }
+  }
 }
 
 function convertIDSelectorsToAttributeSelectors(selector)
 {
   // First we figure out where all the IDs are
   let sep = "";
   let start = null;
   let positions = [];