express-htaccess-middleware/lib/RewriteRule.js

An express middleware that interprets .htaccess rewrite rules.

'use strict';

var _ = require('lodash');

var RewriteCond = require('./RewriteCond');


function RewriteRule(baseRule) {
  _.assign(this, baseRule);

  this.substitution = this.substitution.replace(/\\(%|\$)/g, '$1');

  if (typeof this.conditions === 'undefined') {
    this.conditions = [];
  }

  for (var i = 0; i < this.conditions.length; i++) {
    this.conditions[i] = new RewriteCond(this.conditions[i]);
  }

  if (this.flags.indexOf('NC') !== -1) {
    this.re = new RegExp(this.pattern, 'i');
  } else {
    this.re = new RegExp(this.pattern);
  }
}

RewriteRule.prototype.conditionsMatches = function (req) {
  var state = {
    currentIsOr: false,
    prevWasOr: false,
    orConditionMet: false
  };


  for (var i = 0; i < this.conditions.length; i++) {
    state.currentIsOr = (this.conditions[i].flags.indexOf('OR') !== -1);

    // one of the OR condition has been met
    if (state.prevWasOr && state.orConditionMet) {
      state.prevWasOr = state.currentIsOr;
      state.orConditionMet = state.currentIsOr;
      continue;
    }

    // condition isn't met
    if (this.conditions[i].matches(req) === false) {
      if (state.currentIsOr) {
        continue;
      } else {
        return false;
      }
    } else if (state.currentIsOr) {
      state.orConditionMet = true;
      state.prevWasOr = state.currentIsOr;
    }
  }

  return true;
};


RewriteRule.prototype.matches = function (url) {
  var result = this.re.exec(url);

  if (result === null) {
    return null;
  }

  var statusCode = this.getStatusCode();
  if (statusCode > 0) {
    return { type: 'status', code: statusCode };
  }


  var dest = this.substitution;
  // replace RewriteRule backreferences
  for (var i = 1; typeof result[i] !== 'undefined'; i++) {
    dest = dest.replace(new RegExp('\\$' + i, 'g'), result[i]);
  }

  // replace RewriteCond backreferences
  var refIndex = 1;
  for (i = 0; i < this.conditions.length; i++) {
    if (this.conditions[i].matchResult !== null && this.conditions[i].matchResult.length > 1) {
      for (var j = 1; j < this.conditions[i].matchResult.length; j++) {
        dest = dest.replace(new RegExp('%' + refIndex, 'g'), this.conditions[i].matchResult[j]);

        refIndex++;
      }
    }
  }


  statusCode = this.getRedirectStatusCode();
  if (statusCode > 0) {
    return { type: 'redirect', code: statusCode, dest: dest };
  }

  var skipCount = this.getSkipCount();
  if (skipCount > 0) {
    return { type: 'skip', count: skipCount, dest: dest };
  }

  return { type: 'content', dest: dest };
};


RewriteRule.prototype.getRedirectStatusCode = function () {
  for (var i = 0; i < this.flags.length; i++) {
    if (this.flags[i].indexOf('R=') === 0) {
      return parseInt(this.flags[i].substring(2), 10);
    }
  }

  return (this.flags.indexOf('R') !== -1 ? 302 : 0);
};


RewriteRule.prototype.getStatusCode = function () {
  if (this.flags.indexOf('F') !== -1) {
    return 403;
  } else if (this.flags.indexOf('G') !== -1) {
    return 410;
  }

  return 0;
};


RewriteRule.prototype.getSkipCount = function () {
  for (var i = 0; i < this.flags.length; i++) {
    if (this.flags[i].indexOf('S=') === 0) {
      return parseInt(this.flags[i].substring(2), 10);
    }
  }

  return 0;
};


module.exports = RewriteRule;