// Copyright 2012 Joyent, Inc. All rights reserved.

var assert = require('assert-plus'); var crypto = require('crypto'); var http = require('http'); var util = require('util'); var sshpk = require('sshpk'); var jsprim = require('jsprim'); var utils = require('./utils');

var sprintf = require('util').format;

var HASH_ALGOS = utils.HASH_ALGOS; var PK_ALGOS = utils.PK_ALGOS; var InvalidAlgorithmError = utils.InvalidAlgorithmError; var HttpSignatureError = utils.HttpSignatureError; var validateAlgorithm = utils.validateAlgorithm;

///— Globals

var AUTHZ_FMT =

'Signature keyId="%s",algorithm="%s",headers="%s",signature="%s"';

///— Specific Errors

function MissingHeaderError(message) {

HttpSignatureError.call(this, message, MissingHeaderError);

} util.inherits(MissingHeaderError, HttpSignatureError);

function StrictParsingError(message) {

HttpSignatureError.call(this, message, StrictParsingError);

} util.inherits(StrictParsingError, HttpSignatureError);

/* See createSigner() */ function RequestSigner(options) {

assert.object(options, 'options');

var alg = [];
if (options.algorithm !== undefined) {
  assert.string(options.algorithm, 'options.algorithm');
  alg = validateAlgorithm(options.algorithm);
}
this.rs_alg = alg;

/*
 * RequestSigners come in two varieties: ones with an rs_signFunc, and ones
 * with an rs_signer.
 *
 * rs_signFunc-based RequestSigners have to build up their entire signing
 * string within the rs_lines array and give it to rs_signFunc as a single
 * concat'd blob. rs_signer-based RequestSigners can add a line at a time to
 * their signing state by using rs_signer.update(), thus only needing to
 * buffer the hash function state and one line at a time.
 */
if (options.sign !== undefined) {
  assert.func(options.sign, 'options.sign');
  this.rs_signFunc = options.sign;

} else if (alg[0] === 'hmac' && options.key !== undefined) {
  assert.string(options.keyId, 'options.keyId');
  this.rs_keyId = options.keyId;

  if (typeof (options.key) !== 'string' && !Buffer.isBuffer(options.key))
    throw (new TypeError('options.key for HMAC must be a string or Buffer'));

  /*
   * Make an rs_signer for HMACs, not a rs_signFunc -- HMACs digest their
   * data in chunks rather than requiring it all to be given in one go
   * at the end, so they are more similar to signers than signFuncs.
   */
  this.rs_signer = crypto.createHmac(alg[1].toUpperCase(), options.key);
  this.rs_signer.sign = function () {
    var digest = this.digest('base64');
    return ({
      hashAlgorithm: alg[1],
      toString: function () { return (digest); }
    });
  };

} else if (options.key !== undefined) {
  var key = options.key;
  if (typeof (key) === 'string' || Buffer.isBuffer(key))
    key = sshpk.parsePrivateKey(key);

  assert.ok(sshpk.PrivateKey.isPrivateKey(key, [1, 2]),
    'options.key must be a sshpk.PrivateKey');
  this.rs_key = key;

  assert.string(options.keyId, 'options.keyId');
  this.rs_keyId = options.keyId;

  if (!PK_ALGOS[key.type]) {
    throw (new InvalidAlgorithmError(key.type.toUpperCase() + ' type ' +
      'keys are not supported'));
  }

  if (alg[0] !== undefined && key.type !== alg[0]) {
    throw (new InvalidAlgorithmError('options.key must be a ' +
      alg[0].toUpperCase() + ' key, was given a ' +
      key.type.toUpperCase() + ' key instead'));
  }

  this.rs_signer = key.createSign(alg[1]);

} else {
  throw (new TypeError('options.sign (func) or options.key is required'));
}

this.rs_headers = [];
this.rs_lines = [];

}

/**

* Adds a header to be signed, with its value, into this signer.
*
* @param {String} header
* @param {String} value
* @return {String} value written
*/

RequestSigner.prototype.writeHeader = function (header, value) {

assert.string(header, 'header');
header = header.toLowerCase();
assert.string(value, 'value');

this.rs_headers.push(header);

if (this.rs_signFunc) {
  this.rs_lines.push(header + ': ' + value);

} else {
  var line = header + ': ' + value;
  if (this.rs_headers.length > 0)
    line = '\n' + line;
  this.rs_signer.update(line);
}

return (value);

};

/**

* Adds a default Date header, returning its value.
*
* @return {String}
*/

RequestSigner.prototype.writeDateHeader = function () {

return (this.writeHeader('date', jsprim.rfc1123(new Date())));

};

/**

* Adds the request target line to be signed.
*
* @param {String} method, HTTP method (e.g. 'get', 'post', 'put')
* @param {String} path
*/

RequestSigner.prototype.writeTarget = function (method, path) {

assert.string(method, 'method');
assert.string(path, 'path');
method = method.toLowerCase();
this.writeHeader('(request-target)', method + ' ' + path);

};

/**

* Calculate the value for the Authorization header on this request
* asynchronously.
*
* @param {Func} callback (err, authz)
*/

RequestSigner.prototype.sign = function (cb) {

assert.func(cb, 'callback');

if (this.rs_headers.length < 1)
  throw (new Error('At least one header must be signed'));

var alg, authz;
if (this.rs_signFunc) {
  var data = this.rs_lines.join('\n');
  var self = this;
  this.rs_signFunc(data, function (err, sig) {
    if (err) {
      cb(err);
      return;
    }
    try {
      assert.object(sig, 'signature');
      assert.string(sig.keyId, 'signature.keyId');
      assert.string(sig.algorithm, 'signature.algorithm');
      assert.string(sig.signature, 'signature.signature');
      alg = validateAlgorithm(sig.algorithm);

      authz = sprintf(AUTHZ_FMT,
        sig.keyId,
        sig.algorithm,
        self.rs_headers.join(' '),
        sig.signature);
    } catch (e) {
      cb(e);
      return;
    }
    cb(null, authz);
  });

} else {
  try {
    var sigObj = this.rs_signer.sign();
  } catch (e) {
    cb(e);
    return;
  }
  alg = (this.rs_alg[0] || this.rs_key.type) + '-' + sigObj.hashAlgorithm;
  var signature = sigObj.toString();
  authz = sprintf(AUTHZ_FMT,
    this.rs_keyId,
    alg,
    this.rs_headers.join(' '),
    signature);
  cb(null, authz);
}

};

///— Exported API

module.exports = {

/**
 * Identifies whether a given object is a request signer or not.
 *
 * @param {Object} object, the object to identify
 * @returns {Boolean}
 */
isSigner: function (obj) {
  if (typeof (obj) === 'object' && obj instanceof RequestSigner)
    return (true);
  return (false);
},

/**
 * Creates a request signer, used to asynchronously build a signature
 * for a request (does not have to be an http.ClientRequest).
 *
 * @param {Object} options, either:
 *                   - {String} keyId
 *                   - {String|Buffer} key
 *                   - {String} algorithm (optional, required for HMAC)
 *                 or:
 *                   - {Func} sign (data, cb)
 * @return {RequestSigner}
 */
createSigner: function createSigner(options) {
  return (new RequestSigner(options));
},

/**
 * Adds an 'Authorization' header to an http.ClientRequest object.
 *
 * Note that this API will add a Date header if it's not already set. Any
 * other headers in the options.headers array MUST be present, or this
 * will throw.
 *
 * You shouldn't need to check the return type; it's just there if you want
 * to be pedantic.
 *
 * The optional flag indicates whether parsing should use strict enforcement
 * of the version draft-cavage-http-signatures-04 of the spec or beyond.
 * The default is to be loose and support
 * older versions for compatibility.
 *
 * @param {Object} request an instance of http.ClientRequest.
 * @param {Object} options signing parameters object:
 *                   - {String} keyId required.
 *                   - {String} key required (either a PEM or HMAC key).
 *                   - {Array} headers optional; defaults to ['date'].
 *                   - {String} algorithm optional (unless key is HMAC);
 *                              default is the same as the sshpk default
 *                              signing algorithm for the type of key given
 *                   - {String} httpVersion optional; defaults to '1.1'.
 *                   - {Boolean} strict optional; defaults to 'false'.
 * @return {Boolean} true if Authorization (and optionally Date) were added.
 * @throws {TypeError} on bad parameter types (input).
 * @throws {InvalidAlgorithmError} if algorithm was bad or incompatible with
 *                                 the given key.
 * @throws {sshpk.KeyParseError} if key was bad.
 * @throws {MissingHeaderError} if a header to be signed was specified but
 *                              was not present.
 */
signRequest: function signRequest(request, options) {
  assert.object(request, 'request');
  assert.object(options, 'options');
  assert.optionalString(options.algorithm, 'options.algorithm');
  assert.string(options.keyId, 'options.keyId');
  assert.optionalArrayOfString(options.headers, 'options.headers');
  assert.optionalString(options.httpVersion, 'options.httpVersion');

  if (!request.getHeader('Date'))
    request.setHeader('Date', jsprim.rfc1123(new Date()));
  if (!options.headers)
    options.headers = ['date'];
  if (!options.httpVersion)
    options.httpVersion = '1.1';

  var alg = [];
  if (options.algorithm) {
    options.algorithm = options.algorithm.toLowerCase();
    alg = validateAlgorithm(options.algorithm);
  }

  var i;
  var stringToSign = '';
  for (i = 0; i < options.headers.length; i++) {
    if (typeof (options.headers[i]) !== 'string')
      throw new TypeError('options.headers must be an array of Strings');

    var h = options.headers[i].toLowerCase();

    if (h === 'request-line') {
      if (!options.strict) {
        /**
         * We allow headers from the older spec drafts if strict parsing isn't
         * specified in options.
         */
        stringToSign +=
          request.method + ' ' + request.path + ' HTTP/' +
          options.httpVersion;
      } else {
        /* Strict parsing doesn't allow older draft headers. */
        throw (new StrictParsingError('request-line is not a valid header ' +
          'with strict parsing enabled.'));
      }
    } else if (h === '(request-target)') {
      stringToSign +=
        '(request-target): ' + request.method.toLowerCase() + ' ' +
        request.path;
    } else {
      var value = request.getHeader(h);
      if (value === undefined || value === '') {
        throw new MissingHeaderError(h + ' was not in the request');
      }
      stringToSign += h + ': ' + value;
    }

    if ((i + 1) < options.headers.length)
      stringToSign += '\n';
  }

  /* This is just for unit tests. */
  if (request.hasOwnProperty('_stringToSign')) {
    request._stringToSign = stringToSign;
  }

  var signature;
  if (alg[0] === 'hmac') {
    if (typeof (options.key) !== 'string' && !Buffer.isBuffer(options.key))
      throw (new TypeError('options.key must be a string or Buffer'));

    var hmac = crypto.createHmac(alg[1].toUpperCase(), options.key);
    hmac.update(stringToSign);
    signature = hmac.digest('base64');

  } else {
    var key = options.key;
    if (typeof (key) === 'string' || Buffer.isBuffer(key))
      key = sshpk.parsePrivateKey(options.key);

    assert.ok(sshpk.PrivateKey.isPrivateKey(key, [1, 2]),
      'options.key must be a sshpk.PrivateKey');

    if (!PK_ALGOS[key.type]) {
      throw (new InvalidAlgorithmError(key.type.toUpperCase() + ' type ' +
        'keys are not supported'));
    }

    if (alg[0] !== undefined && key.type !== alg[0]) {
      throw (new InvalidAlgorithmError('options.key must be a ' +
        alg[0].toUpperCase() + ' key, was given a ' +
        key.type.toUpperCase() + ' key instead'));
    }

    var signer = key.createSign(alg[1]);
    signer.update(stringToSign);
    var sigObj = signer.sign();
    if (!HASH_ALGOS[sigObj.hashAlgorithm]) {
      throw (new InvalidAlgorithmError(sigObj.hashAlgorithm.toUpperCase() +
        ' is not a supported hash algorithm'));
    }
    options.algorithm = key.type + '-' + sigObj.hashAlgorithm;
    signature = sigObj.toString();
    assert.notStrictEqual(signature, '', 'empty signature produced');
  }

  request.setHeader('Authorization', sprintf(AUTHZ_FMT,
                                             options.keyId,
                                             options.algorithm,
                                             options.headers.join(' '),
                                             signature));

  return true;
}

};