1var JsonWebTokenError = require('./lib/JsonWebTokenError');
  2var NotBeforeError    = require('./lib/NotBeforeError');
  3var TokenExpiredError = require('./lib/TokenExpiredError');
  4var decode            = require('./decode');
  5var jws               = require('jws');
  6var ms                = require('ms');
  7var xtend             = require('xtend');
  8
  9module.exports = function (jwtString, secretOrPublicKey, options, callback) {
 10  if ((typeof options === 'function') && !callback) {
 11    callback = options;
 12    options = {};
 13  }
 14
 15  if (!options) {
 16    options = {};
 17  }
 18
 19  //clone this object since we are going to mutate it.
 20  options = xtend(options);
 21  var done;
 22
 23  if (callback) {
 24    done = function() {
 25      var args = Array.prototype.slice.call(arguments, 0);
 26      return process.nextTick(function() {
 27        callback.apply(null, args);
 28      });
 29    };
 30  } else {
 31    done = function(err, data) {
 32      if (err) throw err;
 33      return data;
 34    };
 35  }
 36
 37  if (!jwtString){
 38    return done(new JsonWebTokenError('jwt must be provided'));
 39  }
 40
 41  var parts = jwtString.split('.');
 42
 43  if (parts.length !== 3){
 44    return done(new JsonWebTokenError('jwt malformed'));
 45  }
 46
 47  var hasSignature = parts[2].trim() !== '';
 48
 49  if (!hasSignature && secretOrPublicKey){
 50    return done(new JsonWebTokenError('jwt signature is required'));
 51  }
 52
 53  if (hasSignature && !secretOrPublicKey) {
 54    return done(new JsonWebTokenError('secret or public key must be provided'));
 55  }
 56
 57  if (!hasSignature && !options.algorithms) {
 58    options.algorithms = ['none'];
 59  }
 60
 61  if (!options.algorithms) {
 62    options.algorithms = ~secretOrPublicKey.toString().indexOf('BEGIN CERTIFICATE') ||
 63                         ~secretOrPublicKey.toString().indexOf('BEGIN PUBLIC KEY') ?
 64                          [ 'RS256','RS384','RS512','ES256','ES384','ES512' ] :
 65                         ~secretOrPublicKey.toString().indexOf('BEGIN RSA PUBLIC KEY') ?
 66                          [ 'RS256','RS384','RS512' ] :
 67                          [ 'HS256','HS384','HS512' ];
 68
 69  }
 70
 71  var decodedToken;
 72  try {
 73    decodedToken = jws.decode(jwtString);
 74  } catch(err) {
 75    return done(new JsonWebTokenError('invalid token'));
 76  }
 77
 78  if (!decodedToken) {
 79    return done(new JsonWebTokenError('invalid token'));
 80  }
 81
 82  var header = decodedToken.header;
 83
 84  if (!~options.algorithms.indexOf(header.alg)) {
 85    return done(new JsonWebTokenError('invalid algorithm'));
 86  }
 87
 88  var valid;
 89
 90  try {
 91    valid = jws.verify(jwtString, header.alg, secretOrPublicKey);
 92  } catch (e) {
 93    return done(e);
 94  }
 95
 96  if (!valid)
 97    return done(new JsonWebTokenError('invalid signature'));
 98
 99  var payload;
100
101  try {
102    payload = decode(jwtString);
103  } catch(err) {
104    return done(err);
105  }
106
107  if (typeof payload.nbf !== 'undefined' && !options.ignoreNotBefore) {
108    if (typeof payload.nbf !== 'number') {
109      return done(new JsonWebTokenError('invalid nbf value'));
110    }
111    if (payload.nbf > Math.floor(Date.now() / 1000) + (options.clockTolerance || 0)) {
112      return done(new NotBeforeError('jwt not active', new Date(payload.nbf * 1000)));
113    }
114  }
115
116  if (typeof payload.exp !== 'undefined' && !options.ignoreExpiration) {
117    if (typeof payload.exp !== 'number') {
118      return done(new JsonWebTokenError('invalid exp value'));
119    }
120    if (Math.floor(Date.now() / 1000) >= payload.exp + (options.clockTolerance || 0)) {
121      return done(new TokenExpiredError('jwt expired', new Date(payload.exp * 1000)));
122    }
123  }
124
125  if (options.audience) {
126    var audiences = Array.isArray(options.audience)? options.audience : [options.audience];
127    var target = Array.isArray(payload.aud) ? payload.aud : [payload.aud];
128
129    var match = target.some(function(aud) { return audiences.indexOf(aud) != -1; });
130
131    if (!match)
132      return done(new JsonWebTokenError('jwt audience invalid. expected: ' + audiences.join(' or ')));
133  }
134
135  if (options.issuer) {
136    var invalid_issuer =
137        (typeof options.issuer === 'string' && payload.iss !== options.issuer) ||
138        (Array.isArray(options.issuer) && options.issuer.indexOf(payload.iss) === -1);
139
140    if (invalid_issuer) {
141      return done(new JsonWebTokenError('jwt issuer invalid. expected: ' + options.issuer));
142    }
143  }
144
145  if (options.subject) {
146    if (payload.sub !== options.subject) {
147      return done(new JsonWebTokenError('jwt subject invalid. expected: ' + options.subject));
148    }
149  }
150
151  if (options.jwtid) {
152    if (payload.jti !== options.jwtid) {
153      return done(new JsonWebTokenError('jwt jwtid invalid. expected: ' + options.jwtid));
154    }
155  }
156
157  if (options.maxAge) {
158    var maxAge = ms(options.maxAge);
159    if (typeof payload.iat !== 'number') {
160      return done(new JsonWebTokenError('iat required when maxAge is specified'));
161    }
162    if (Date.now() - (payload.iat * 1000) > maxAge + (options.clockTolerance || 0) * 1000) {
163      return done(new TokenExpiredError('maxAge exceeded', new Date(payload.iat * 1000 + maxAge)));
164    }
165  }
166
167  return done(null, payload);
168};