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rules.js
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rules.js
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"use strict";
// Stubs so this runs under nodejs. They get overwritten later by util.js
var VERB=1;
var DBUG=2;
var INFO=3;
var NOTE=4;
var WARN=5;
function log(){}
// To reduce memory usage for the numerous rules/cookies with trivial rules
const trivial_rule_to = "https:";
const trivial_rule_from_c = new RegExp("^http:");
const trivial_cookie_name_c = new RegExp(".*");
const trivial_cookie_host_c = new RegExp(".*");
/**
* A single rule
* @param from
* @param to
* @constructor
*/
function Rule(from, to) {
if (from === "^http:" && to === "https:") {
// This is a trivial rule, rewriting http->https with no complex RegExp.
this.to = trivial_rule_to;
this.from_c = trivial_rule_from_c;
} else {
// This is a non-trivial rule.
this.to = to;
this.from_c = new RegExp(from);
}
}
/**
* Regex-Compile a pattern
* @param pattern The pattern to compile
* @constructor
*/
function Exclusion(pattern) {
this.pattern_c = new RegExp(pattern);
}
/**
* Generates a CookieRule
* @param host The host regex to compile
* @param cookiename The cookie name Regex to compile
* @constructor
*/
function CookieRule(host, cookiename) {
if (host === ".*" || host === ".+" || host === ".") {
// Some cookie rules trivially match any host.
this.host_c = trivial_cookie_host_c;
} else {
this.host_c = new RegExp(host);
}
if (cookiename === ".*" || cookiename === ".+" || cookiename === ".") {
// About 50% of cookie rules trivially match any name.
this.name_c = trivial_cookie_name_c;
} else {
this.name_c = new RegExp(cookiename);
}
}
/**
*A collection of rules
* @param set_name The name of this set
* @param default_state activity state
* @param note Note will be displayed in popup
* @constructor
*/
function RuleSet(set_name, default_state, note) {
this.name = set_name;
this.rules = [];
this.exclusions = null;
this.cookierules = null;
this.active = default_state;
this.default_state = default_state;
this.note = note;
}
RuleSet.prototype = {
/**
* Check if a URI can be rewritten and rewrite it
* @param urispec The uri to rewrite
* @returns {*} null or the rewritten uri
*/
apply: function(urispec) {
var returl = null;
// If we're covered by an exclusion, go home
if (this.exclusions !== null) {
for (var i = 0; i < this.exclusions.length; ++i) {
if (this.exclusions[i].pattern_c.test(urispec)) {
log(DBUG, "excluded uri " + urispec);
return null;
}
}
}
// Okay, now find the first rule that triggers
for(var i = 0; i < this.rules.length; ++i) {
returl = urispec.replace(this.rules[i].from_c,
this.rules[i].to);
if (returl != urispec) {
return returl;
}
}
return null;
}
};
/**
* Initialize Rule Sets
* @param ruleActiveStates default state for rules
* @constructor
*/
function RuleSets(ruleActiveStates) {
// Load rules into structure
this.targets = {};
// A cache for potentiallyApplicableRulesets
this.ruleCache = new Map();
// A cache for cookie hostnames.
this.cookieHostCache = new Map();
// A hash of rule name -> active status (true/false).
this.ruleActiveStates = ruleActiveStates;
// A regex to match platform-specific features
this.localPlatformRegexp = new RegExp("chromium");
}
RuleSets.prototype = {
/**
* Iterate through data XML and load rulesets
*/
addFromXml: function(ruleXml) {
var sets = ruleXml.getElementsByTagName("ruleset");
for (var i = 0; i < sets.length; ++i) {
try {
this.parseOneRuleset(sets[i]);
} catch (e) {
log(WARN, 'Error processing ruleset:' + e);
}
}
},
/**
* Load a user rule
* @param params
* @returns {boolean}
*/
addUserRule : function(params) {
log(INFO, 'adding new user rule for ' + JSON.stringify(params));
var new_rule_set = new RuleSet(params.host, true, "user rule");
var new_rule = new Rule(params.urlMatcher, params.redirectTo);
new_rule_set.rules.push(new_rule);
if (!(params.host in this.targets)) {
this.targets[params.host] = [];
}
this.ruleCache.delete(params.host);
// TODO: maybe promote this rule?
this.targets[params.host].push(new_rule_set);
if (new_rule_set.name in this.ruleActiveStates) {
new_rule_set.active = (this.ruleActiveStates[new_rule_set.name] == "true");
}
log(INFO, 'done adding rule');
return true;
},
/**
* Does the loading of a ruleset.
* @param ruletag The whole <ruleset> tag to parse
*/
parseOneRuleset: function(ruletag) {
var default_state = true;
var note = "";
var default_off = ruletag.getAttribute("default_off");
if (default_off) {
default_state = false;
note += default_off + "\n";
}
// If a ruleset declares a platform, and we don't match it, treat it as
// off-by-default. In practice, this excludes "mixedcontent" & "cacert" rules.
var platform = ruletag.getAttribute("platform");
if (platform) {
if (platform.search(this.localPlatformRegexp) == -1) {
default_state = false;
}
note += "Platform(s): " + platform + "\n";
}
var rule_set = new RuleSet(ruletag.getAttribute("name"),
default_state,
note.trim());
// Read user prefs
if (rule_set.name in this.ruleActiveStates) {
rule_set.active = (this.ruleActiveStates[rule_set.name] == "true");
}
var rules = ruletag.getElementsByTagName("rule");
for(var j = 0; j < rules.length; j++) {
rule_set.rules.push(new Rule(rules[j].getAttribute("from"),
rules[j].getAttribute("to")));
}
var exclusions = ruletag.getElementsByTagName("exclusion");
if (exclusions.length > 0) {
rule_set.exclusions = [];
for (var j = 0; j < exclusions.length; j++) {
rule_set.exclusions.push(
new Exclusion(exclusions[j].getAttribute("pattern")));
}
}
var cookierules = ruletag.getElementsByTagName("securecookie");
if (cookierules.length > 0) {
rule_set.cookierules = [];
for(var j = 0; j < cookierules.length; j++) {
rule_set.cookierules.push(
new CookieRule(cookierules[j].getAttribute("host"),
cookierules[j].getAttribute("name")));
}
}
var targets = ruletag.getElementsByTagName("target");
for(var j = 0; j < targets.length; j++) {
var host = targets[j].getAttribute("host");
if (!(host in this.targets)) {
this.targets[host] = [];
}
this.targets[host].push(rule_set);
}
},
/**
* Return a list of rulesets that apply to this host
* @param host The host to check
* @returns {*} (empty) list
*/
potentiallyApplicableRulesets: function(host) {
// Have we cached this result? If so, return it!
var cached_item = this.ruleCache.get(host);
if (cached_item !== undefined) {
log(DBUG, "Ruleset cache hit for " + host + " items:" + cached_item.length);
return cached_item;
}
log(DBUG, "Ruleset cache miss for " + host);
var tmp;
var results = [];
if (this.targets[host]) {
// Copy the host targets so we don't modify them.
results = results.concat(this.targets[host]);
}
// Ensure host is well-formed (RFC 1035)
if (host.indexOf("..") != -1 || host.length > 255) {
log(WARN,"Malformed host passed to potentiallyApplicableRulesets: " + host);
return null;
}
// Replace each portion of the domain with a * in turn
var segmented = host.split(".");
for (var i = 0; i < segmented.length; ++i) {
tmp = segmented[i];
segmented[i] = "*";
results = results.concat(this.targets[segmented.join(".")]);
segmented[i] = tmp;
}
// now eat away from the left, with *, so that for x.y.z.google.com we
// check *.z.google.com and *.google.com (we did *.y.z.google.com above)
for (var i = 2; i <= segmented.length - 2; ++i) {
var t = "*." + segmented.slice(i,segmented.length).join(".");
results = results.concat(this.targets[t]);
}
// Clean the results list, which may contain duplicates or undefined entries
var resultSet = new Set(results);
resultSet.delete(undefined);
log(DBUG,"Applicable rules for " + host + ":");
if (resultSet.size == 0) {
log(DBUG, " None");
} else {
for (let target of resultSet.values()) {
log(DBUG, " " + target.name);
}
}
// Insert results into the ruleset cache
this.ruleCache.set(host, resultSet);
// Cap the size of the cache. (Limit chosen somewhat arbitrarily)
if (this.ruleCache.size > 1000) {
// Map.prototype.keys() returns keys in insertion order, so this is a FIFO.
this.ruleCache.delete(this.ruleCache.keys().next().value);
}
return resultSet;
},
/**
* Check to see if the Cookie object c meets any of our cookierule criteria for being marked as secure.
* @param cookie The cookie to test
* @returns {*} ruleset or null
*/
shouldSecureCookie: function(cookie) {
var hostname = cookie.domain;
// cookie domain scopes can start with .
while (hostname.charAt(0) == ".") {
hostname = hostname.slice(1);
}
if (!this.safeToSecureCookie(hostname)) {
return null;
}
var potentiallyApplicable = this.potentiallyApplicableRulesets(hostname);
for (let ruleset of potentiallyApplicable) {
if (ruleset.cookierules !== null && ruleset.active) {
for (var j = 0; j < ruleset.cookierules.length; j++) {
var cr = ruleset.cookierules[j];
if (cr.host_c.test(cookie.domain) && cr.name_c.test(cookie.name)) {
return ruleset;
}
}
}
}
return null;
},
/**
* Check if it is secure to secure the cookie (=patch the secure flag in).
* @param domain The domain of the cookie
* @returns {*} true or false
*/
safeToSecureCookie: function(domain) {
// Check if the domain might be being served over HTTP. If so, it isn't
// safe to secure a cookie! We can't always know this for sure because
// observing cookie-changed doesn't give us enough context to know the
// full origin URI.
// First, if there are any redirect loops on this domain, don't secure
// cookies. XXX This is not a very satisfactory heuristic. Sometimes we
// would want to secure the cookie anyway, because the URLs that loop are
// not authenticated or not important. Also by the time the loop has been
// observed and the domain blacklisted, a cookie might already have been
// flagged as secure.
if (domainBlacklist.has(domain)) {
log(INFO, "cookies for " + domain + "blacklisted");
return false;
}
var cached_item = this.cookieHostCache.get(domain);
if (cached_item !== undefined) {
log(DBUG, "Cookie host cache hit for " + domain);
return cached_item;
}
log(DBUG, "Cookie host cache miss for " + domain);
// If we passed that test, make up a random URL on the domain, and see if
// we would HTTPSify that.
var nonce_path = "/" + Math.random().toString();
var test_uri = "http://" + domain + nonce_path + nonce_path;
// Cap the size of the cookie cache (limit chosen somewhat arbitrarily)
if (this.cookieHostCache.size > 250) {
// Map.prototype.keys() returns keys in insertion order, so this is a FIFO.
this.cookieHostCache.delete(this.cookieHostCache.keys().next().value);
}
log(INFO, "Testing securecookie applicability with " + test_uri);
var potentiallyApplicable = this.potentiallyApplicableRulesets(domain);
for (let ruleset of potentiallyApplicable) {
if (!ruleset.active) {
continue;
}
if (ruleset.apply(test_uri)) {
log(INFO, "Cookie domain could be secured.");
this.cookieHostCache.set(domain, true);
return true;
}
}
log(INFO, "Cookie domain could NOT be secured.");
this.cookieHostCache.set(domain, false);
return false;
},
/**
* Rewrite an URI
* @param urispec The uri to rewrite
* @param host The host of this uri
* @returns {*} the new uri or null
*/
rewriteURI: function(urispec, host) {
var newuri = null;
var potentiallyApplicable = this.potentiallyApplicableRulesets(host);
for (let ruleset of potentiallyApplicable) {
if (ruleset.active && (newuri = ruleset.apply(urispec))) {
return newuri;
}
}
return null;
}
};
// Export for HTTPS Rewriter if applicable.
if (typeof exports != 'undefined') {
exports.RuleSets = RuleSets;
}