gecko/toolkit/components/url-classifier/content/multi-querier.js

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#   Tony Chang <tony@google.com> (original author)
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/**
 * This class helps us batch a series of async calls to the db.
 * If any of the tokens is in the database, we fire callback with
 * true as a param.  If all the tokens are not in the  database,
 * we fire callback with false as a param.
 * This is an "Abstract" base class.  Subclasses need to supply
 * the condition_ method.
 *
 * @param tokens Array of strings to lookup in the db
 * @param tableName String name of the table
 * @param callback Function callback function that takes true if the condition
 *        passes.
 */
function MultiQuerier(tokens, tableName, callback) {
  this.tokens_ = tokens;
  this.tableName_ = tableName;
  this.callback_ = callback;
  this.dbservice_ = Cc["@mozilla.org/url-classifier/dbservice;1"]
                    .getService(Ci.nsIUrlClassifierDBService);
  // We put the current token in this variable.
  this.key_ = null;
}

/**
 * Run the remaining tokens against the db.
 */
MultiQuerier.prototype.run = function() {
  if (this.tokens_.length == 0) {
    this.callback_.handleEvent(false);
    this.dbservice_ = null;
    this.callback_ = null;
    return;
  }
  
  this.key_ = this.tokens_.pop();
  G_Debug(this, "Looking up " + this.key_ + " in " + this.tableName_);
  this.dbservice_.exists(this.tableName_, this.key_,
                         BindToObject(this.result_, this));
}

/**
 * Callback from the db.  If the returned value passes the this.condition_
 * test, go ahead and call the main callback.
 */
MultiQuerier.prototype.result_ = function(value) {
  if (this.condition_(value)) {
    this.callback_.handleEvent(true)
    this.dbservice_ = null;
    this.callback_ = null;
  } else {
    this.run();
  }
}

// Subclasses must override this.
MultiQuerier.prototype.condition_ = function(value) {
  throw "MultiQuerier is an abstract base class";
}


/**
 * Concrete MultiQuerier that stops if the key exists in the db.
 */
function ExistsMultiQuerier(tokens, tableName, callback) {
  MultiQuerier.call(this, tokens, tableName, callback);
  this.debugZone = "existsMultiQuerier";
}
ExistsMultiQuerier.inherits(MultiQuerier);

ExistsMultiQuerier.prototype.condition_ = function(value) {
  return value.length > 0;
}


/**
 * Concrete MultiQuerier that looks up a key, decrypts it, then
 * checks the the resulting regular expressions for a match.
 * @param tokens Array of hosts
 */
function EnchashMultiQuerier(tokens, tableName, callback, url) {
  MultiQuerier.call(this, tokens, tableName, callback);
  this.url_ = url;
  this.enchashDecrypter_ = new PROT_EnchashDecrypter();
  this.debugZone = "enchashMultiQuerier";
}
EnchashMultiQuerier.inherits(MultiQuerier);

EnchashMultiQuerier.prototype.run = function() {
  if (this.tokens_.length == 0) {
    this.callback_.handleEvent(false);
    this.dbservice_ = null;
    this.callback_ = null;
    return;
  }
  var host = this.tokens_.pop();
  this.key_ = host;
  var lookupKey = this.enchashDecrypter_.getLookupKey(host);
  this.dbservice_.exists(this.tableName_, lookupKey,
                         BindToObject(this.result_, this));
}

EnchashMultiQuerier.prototype.condition_ = function(encryptedValue) {
  if (encryptedValue.length > 0) {
    // We have encrypted regular expressions for this host. Let's 
    // decrypt them and see if we have a match.
    var decrypted = this.enchashDecrypter_.decryptData(encryptedValue,
                                                       this.key_);
    var res = this.enchashDecrypter_.parseRegExps(decrypted);
    for (var j = 0; j < res.length; j++) {
      if (res[j].test(this.url_)) {
        return true;
      }
    }
  }
  return false;
}