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class-jwt.php
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class-jwt.php
427 lines
| 1 | <?php |
| 2 | /** |
| 3 | * JSON Web Token implementation, based on this spec: |
| 4 | * https://tools.ietf.org/html/rfc7519 |
| 5 | * |
| 6 | * @package Automattic\Jetpack\Extensions\Premium_Content |
| 7 | */ |
| 8 | |
| 9 | namespace Automattic\Jetpack\Extensions\Premium_Content; |
| 10 | |
| 11 | use DateTime; |
| 12 | use DomainException; |
| 13 | use InvalidArgumentException; |
| 14 | use UnexpectedValueException; |
| 15 | |
| 16 | /** |
| 17 | * JSON Web Token implementation, based on this spec: |
| 18 | * https://tools.ietf.org/html/rfc7519 |
| 19 | * |
| 20 | * PHP version 5 |
| 21 | * |
| 22 | * @category Authentication |
| 23 | * @package Authentication_JWT |
| 24 | * @author Neuman Vong <neuman@twilio.com> |
| 25 | * @author Anant Narayanan <anant@php.net> |
| 26 | * @license http://opensource.org/licenses/BSD-3-Clause 3-clause BSD |
| 27 | * @link https://github.com/firebase/php-jwt |
| 28 | */ |
| 29 | class JWT { |
| 30 | /** |
| 31 | * When checking nbf, iat or expiration times, |
| 32 | * we want to provide some extra leeway time to |
| 33 | * account for clock skew. |
| 34 | * |
| 35 | * @var int $leeway The leeway value. |
| 36 | */ |
| 37 | public static $leeway = 0; |
| 38 | |
| 39 | /** |
| 40 | * Allow the current timestamp to be specified. |
| 41 | * Useful for fixing a value within unit testing. |
| 42 | * |
| 43 | * Will default to PHP time() value if null. |
| 44 | * |
| 45 | * @var string $timestamp The timestamp. |
| 46 | */ |
| 47 | public static $timestamp = null; |
| 48 | |
| 49 | /** |
| 50 | * Supported algorithms. |
| 51 | * |
| 52 | * @var array $supported_algs Supported algorithms. |
| 53 | */ |
| 54 | public static $supported_algs = array( |
| 55 | 'HS256' => array( 'hash_hmac', 'SHA256' ), |
| 56 | 'HS512' => array( 'hash_hmac', 'SHA512' ), |
| 57 | 'HS384' => array( 'hash_hmac', 'SHA384' ), |
| 58 | 'RS256' => array( 'openssl', 'SHA256' ), |
| 59 | 'RS384' => array( 'openssl', 'SHA384' ), |
| 60 | 'RS512' => array( 'openssl', 'SHA512' ), |
| 61 | ); |
| 62 | |
| 63 | /** |
| 64 | * Decodes a JWT string into a PHP object. |
| 65 | * |
| 66 | * @param string $jwt The JWT. |
| 67 | * @param string|array $key The key, or map of keys. |
| 68 | * If the algorithm used is asymmetric, this is the public key. |
| 69 | * @param array $allowed_algs List of supported verification algorithms. |
| 70 | * Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'. |
| 71 | * |
| 72 | * @return object The JWT's payload as a PHP object |
| 73 | * |
| 74 | * @throws UnexpectedValueException Provided JWT was invalid. |
| 75 | * @throws SignatureInvalidException Provided JWT was invalid because the signature verification failed. |
| 76 | * @throws InvalidArgumentException Provided JWT is trying to be used before it's eligible as defined by 'nbf'. |
| 77 | * @throws BeforeValidException Provided JWT is trying to be used before it's been created as defined by 'iat'. |
| 78 | * @throws ExpiredException Provided JWT has since expired, as defined by the 'exp' claim. |
| 79 | * |
| 80 | * @uses json_decode |
| 81 | * @uses urlsafe_b64_decode |
| 82 | */ |
| 83 | public static function decode( $jwt, $key, array $allowed_algs = array() ) { |
| 84 | $timestamp = static::$timestamp === null ? time() : static::$timestamp; |
| 85 | |
| 86 | if ( empty( $key ) ) { |
| 87 | throw new InvalidArgumentException( 'Key may not be empty' ); |
| 88 | } |
| 89 | |
| 90 | $tks = explode( '.', $jwt ); |
| 91 | if ( count( $tks ) !== 3 ) { |
| 92 | throw new UnexpectedValueException( 'Wrong number of segments' ); |
| 93 | } |
| 94 | |
| 95 | list( $headb64, $bodyb64, $cryptob64 ) = $tks; |
| 96 | |
| 97 | $header = static::json_decode( static::urlsafe_b64_decode( $headb64 ) ); |
| 98 | if ( null === $header ) { |
| 99 | throw new UnexpectedValueException( 'Invalid header encoding' ); |
| 100 | } |
| 101 | |
| 102 | $payload = static::json_decode( static::urlsafe_b64_decode( $bodyb64 ) ); |
| 103 | if ( null === $payload ) { |
| 104 | throw new UnexpectedValueException( 'Invalid claims encoding' ); |
| 105 | } |
| 106 | |
| 107 | $sig = static::urlsafe_b64_decode( $cryptob64 ); |
| 108 | if ( false === $sig ) { |
| 109 | throw new UnexpectedValueException( 'Invalid signature encoding' ); |
| 110 | } |
| 111 | |
| 112 | if ( empty( $header->alg ) ) { |
| 113 | throw new UnexpectedValueException( 'Empty algorithm' ); |
| 114 | } |
| 115 | |
| 116 | if ( empty( static::$supported_algs[ $header->alg ] ) ) { |
| 117 | throw new UnexpectedValueException( 'Algorithm not supported' ); |
| 118 | } |
| 119 | |
| 120 | if ( ! in_array( $header->alg, $allowed_algs, true ) ) { |
| 121 | throw new UnexpectedValueException( 'Algorithm not allowed' ); |
| 122 | } |
| 123 | |
| 124 | if ( is_array( $key ) || $key instanceof \ArrayAccess ) { |
| 125 | if ( isset( $header->kid ) ) { |
| 126 | if ( ! isset( $key[ $header->kid ] ) ) { |
| 127 | throw new UnexpectedValueException( '"kid" invalid, unable to lookup correct key' ); |
| 128 | } |
| 129 | $key = $key[ $header->kid ]; |
| 130 | } else { |
| 131 | throw new UnexpectedValueException( '"kid" empty, unable to lookup correct key' ); |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | // Check the signature. |
| 136 | if ( ! static::verify( "$headb64.$bodyb64", $sig, $key, $header->alg ) ) { |
| 137 | throw new SignatureInvalidException( 'Signature verification failed' ); |
| 138 | } |
| 139 | |
| 140 | // Check if the nbf if it is defined. This is the time that the |
| 141 | // token can actually be used. If it's not yet that time, abort. |
| 142 | if ( isset( $payload->nbf ) && $payload->nbf > ( $timestamp + static::$leeway ) ) { |
| 143 | throw new BeforeValidException( |
| 144 | 'Cannot handle token prior to ' . gmdate( DateTime::ISO8601, $payload->nbf ) |
| 145 | ); |
| 146 | } |
| 147 | |
| 148 | // Check that this token has been created before 'now'. This prevents |
| 149 | // using tokens that have been created for later use (and haven't |
| 150 | // correctly used the nbf claim). |
| 151 | if ( isset( $payload->iat ) && $payload->iat > ( $timestamp + static::$leeway ) ) { |
| 152 | throw new BeforeValidException( |
| 153 | 'Cannot handle token prior to ' . gmdate( DateTime::ISO8601, $payload->iat ) |
| 154 | ); |
| 155 | } |
| 156 | |
| 157 | // Check if this token has expired. |
| 158 | if ( isset( $payload->exp ) && ( $timestamp - static::$leeway ) >= $payload->exp ) { |
| 159 | throw new ExpiredException( 'Expired token' ); |
| 160 | } |
| 161 | |
| 162 | return $payload; |
| 163 | } |
| 164 | |
| 165 | /** |
| 166 | * Converts and signs a PHP object or array into a JWT string. |
| 167 | * |
| 168 | * @param object|array $payload PHP object or array. |
| 169 | * @param string $key The secret key. |
| 170 | * If the algorithm used is asymmetric, this is the private key. |
| 171 | * @param string $alg The signing algorithm. |
| 172 | * Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'. |
| 173 | * @param mixed $key_id The key ID. |
| 174 | * @param array $head An array with header elements to attach. |
| 175 | * |
| 176 | * @return string A signed JWT |
| 177 | * |
| 178 | * @uses json_encode |
| 179 | * @uses urlsafe_b64_decode |
| 180 | */ |
| 181 | public static function encode( $payload, $key, $alg = 'HS256', $key_id = null, $head = null ) { |
| 182 | $header = array( |
| 183 | 'typ' => 'JWT', |
| 184 | 'alg' => $alg, |
| 185 | ); |
| 186 | |
| 187 | if ( null !== $key_id ) { |
| 188 | $header['kid'] = $key_id; |
| 189 | } |
| 190 | |
| 191 | if ( isset( $head ) && is_array( $head ) ) { |
| 192 | $header = array_merge( $head, $header ); |
| 193 | } |
| 194 | |
| 195 | $segments = array(); |
| 196 | $segments[] = static::urlsafe_b64_encode( static::json_encode( $header ) ); |
| 197 | $segments[] = static::urlsafe_b64_encode( static::json_encode( $payload ) ); |
| 198 | $signing_input = implode( '.', $segments ); |
| 199 | |
| 200 | $signature = static::sign( $signing_input, $key, $alg ); |
| 201 | $segments[] = static::urlsafe_b64_encode( $signature ); |
| 202 | |
| 203 | return implode( '.', $segments ); |
| 204 | } |
| 205 | |
| 206 | /** |
| 207 | * Sign a string with a given key and algorithm. |
| 208 | * |
| 209 | * @param string $msg The message to sign. |
| 210 | * @param string|resource $key The secret key. |
| 211 | * @param string $alg The signing algorithm. |
| 212 | * Supported algorithms are 'HS256', 'HS384', 'HS512' and 'RS256'. |
| 213 | * |
| 214 | * @return string An encrypted message |
| 215 | * |
| 216 | * @throws DomainException Unsupported algorithm was specified. |
| 217 | */ |
| 218 | public static function sign( $msg, $key, $alg = 'HS256' ) { |
| 219 | if ( empty( static::$supported_algs[ $alg ] ) ) { |
| 220 | throw new DomainException( 'Algorithm not supported' ); |
| 221 | } |
| 222 | list($function, $algorithm) = static::$supported_algs[ $alg ]; |
| 223 | switch ( $function ) { |
| 224 | case 'hash_hmac': |
| 225 | return hash_hmac( $algorithm, $msg, $key, true ); |
| 226 | case 'openssl': |
| 227 | $signature = ''; |
| 228 | $success = openssl_sign( $msg, $signature, $key, $algorithm ); |
| 229 | if ( ! $success ) { |
| 230 | throw new DomainException( 'OpenSSL unable to sign data' ); |
| 231 | } else { |
| 232 | return $signature; |
| 233 | } |
| 234 | } |
| 235 | } |
| 236 | |
| 237 | /** |
| 238 | * Verify a signature with the message, key and method. Not all methods |
| 239 | * are symmetric, so we must have a separate verify and sign method. |
| 240 | * |
| 241 | * @param string $msg The original message (header and body). |
| 242 | * @param string $signature The original signature. |
| 243 | * @param string|resource $key For HS*, a string key works. for RS*, must be a resource of an openssl public key. |
| 244 | * @param string $alg The algorithm. |
| 245 | * |
| 246 | * @return bool |
| 247 | * |
| 248 | * @throws DomainException Invalid Algorithm or OpenSSL failure. |
| 249 | */ |
| 250 | private static function verify( $msg, $signature, $key, $alg ) { |
| 251 | if ( empty( static::$supported_algs[ $alg ] ) ) { |
| 252 | throw new DomainException( 'Algorithm not supported' ); |
| 253 | } |
| 254 | |
| 255 | list($function, $algorithm) = static::$supported_algs[ $alg ]; |
| 256 | switch ( $function ) { |
| 257 | case 'openssl': |
| 258 | $success = openssl_verify( $msg, $signature, $key, $algorithm ); |
| 259 | |
| 260 | if ( 1 === $success ) { |
| 261 | return true; |
| 262 | } elseif ( 0 === $success ) { |
| 263 | return false; |
| 264 | } |
| 265 | |
| 266 | // returns 1 on success, 0 on failure, -1 on error. |
| 267 | throw new DomainException( |
| 268 | 'OpenSSL error: ' . openssl_error_string() |
| 269 | ); |
| 270 | case 'hash_hmac': |
| 271 | default: |
| 272 | $hash = hash_hmac( $algorithm, $msg, $key, true ); |
| 273 | |
| 274 | if ( function_exists( 'hash_equals' ) ) { |
| 275 | return hash_equals( $signature, $hash ); |
| 276 | } |
| 277 | |
| 278 | $len = min( static::safe_strlen( $signature ), static::safe_strlen( $hash ) ); |
| 279 | |
| 280 | $status = 0; |
| 281 | |
| 282 | for ( $i = 0; $i < $len; $i++ ) { |
| 283 | $status |= ( ord( $signature[ $i ] ) ^ ord( $hash[ $i ] ) ); |
| 284 | } |
| 285 | |
| 286 | $status |= ( static::safe_strlen( $signature ) ^ static::safe_strlen( $hash ) ); |
| 287 | |
| 288 | return ( 0 === $status ); |
| 289 | } |
| 290 | } |
| 291 | |
| 292 | /** |
| 293 | * Decode a JSON string into a PHP object. |
| 294 | * |
| 295 | * @param string $input JSON string. |
| 296 | * |
| 297 | * @return object Object representation of JSON string |
| 298 | * |
| 299 | * @throws DomainException Provided string was invalid JSON. |
| 300 | */ |
| 301 | public static function json_decode( $input ) { |
| 302 | $obj = json_decode( $input, false, 512, JSON_BIGINT_AS_STRING ); |
| 303 | $errno = json_last_error(); |
| 304 | |
| 305 | if ( $errno ) { |
| 306 | static::handle_json_error( $errno ); |
| 307 | } elseif ( null === $obj && 'null' !== $input ) { |
| 308 | throw new DomainException( 'Null result with non-null input' ); |
| 309 | } |
| 310 | return $obj; |
| 311 | } |
| 312 | |
| 313 | /** |
| 314 | * Encode a PHP object into a JSON string. |
| 315 | * |
| 316 | * @param object|array $input A PHP object or array. |
| 317 | * |
| 318 | * @return string JSON representation of the PHP object or array. |
| 319 | * |
| 320 | * @throws DomainException Provided object could not be encoded to valid JSON. |
| 321 | */ |
| 322 | public static function json_encode( $input ) { |
| 323 | $json = wp_json_encode( $input ); |
| 324 | $errno = json_last_error(); |
| 325 | |
| 326 | if ( $errno ) { |
| 327 | static::handle_json_error( $errno ); |
| 328 | } elseif ( 'null' === $json && null !== $input ) { |
| 329 | throw new DomainException( 'Null result with non-null input' ); |
| 330 | } |
| 331 | return $json; |
| 332 | } |
| 333 | |
| 334 | /** |
| 335 | * Decode a string with URL-safe Base64. |
| 336 | * |
| 337 | * @param string $input A Base64 encoded string. |
| 338 | * |
| 339 | * @return string A decoded string |
| 340 | */ |
| 341 | public static function urlsafe_b64_decode( $input ) { |
| 342 | $remainder = strlen( $input ) % 4; |
| 343 | if ( $remainder ) { |
| 344 | $padlen = 4 - $remainder; |
| 345 | $input .= str_repeat( '=', $padlen ); |
| 346 | } |
| 347 | // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_decode |
| 348 | return base64_decode( strtr( $input, '-_', '+/' ) ); |
| 349 | } |
| 350 | |
| 351 | /** |
| 352 | * Encode a string with URL-safe Base64. |
| 353 | * |
| 354 | * @param string $input The string you want encoded. |
| 355 | * |
| 356 | * @return string The base64 encode of what you passed in |
| 357 | */ |
| 358 | public static function urlsafe_b64_encode( $input ) { |
| 359 | // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode |
| 360 | return str_replace( '=', '', strtr( base64_encode( $input ), '+/', '-_' ) ); |
| 361 | } |
| 362 | |
| 363 | /** |
| 364 | * Helper method to create a JSON error. |
| 365 | * |
| 366 | * @param int $errno An error number from json_last_error(). |
| 367 | * @throws DomainException . |
| 368 | * |
| 369 | * @return never |
| 370 | */ |
| 371 | private static function handle_json_error( $errno ) { |
| 372 | $messages = array( |
| 373 | JSON_ERROR_DEPTH => 'Maximum stack depth exceeded', |
| 374 | JSON_ERROR_STATE_MISMATCH => 'Invalid or malformed JSON', |
| 375 | JSON_ERROR_CTRL_CHAR => 'Unexpected control character found', |
| 376 | JSON_ERROR_SYNTAX => 'Syntax error, malformed JSON', |
| 377 | JSON_ERROR_UTF8 => 'Malformed UTF-8 characters', |
| 378 | ); |
| 379 | throw new DomainException( |
| 380 | isset( $messages[ $errno ] ) |
| 381 | ? $messages[ $errno ] |
| 382 | : 'Unknown JSON error: ' . $errno |
| 383 | ); |
| 384 | } |
| 385 | |
| 386 | /** |
| 387 | * Get the number of bytes in cryptographic strings. |
| 388 | * |
| 389 | * @param string $str . |
| 390 | * |
| 391 | * @return int |
| 392 | */ |
| 393 | private static function safe_strlen( $str ) { |
| 394 | if ( function_exists( 'mb_strlen' ) ) { |
| 395 | return mb_strlen( $str, '8bit' ); |
| 396 | } |
| 397 | return strlen( $str ); |
| 398 | } |
| 399 | } |
| 400 | |
| 401 | // phpcs:disable |
| 402 | if ( ! class_exists( 'SignatureInvalidException' ) ) { |
| 403 | /** |
| 404 | * SignatureInvalidException |
| 405 | * |
| 406 | * @package Automattic\Jetpack\Extensions\Premium_Content |
| 407 | */ |
| 408 | class SignatureInvalidException extends \UnexpectedValueException { } |
| 409 | } |
| 410 | if ( ! class_exists( 'ExpiredException' ) ) { |
| 411 | /** |
| 412 | * ExpiredException |
| 413 | * |
| 414 | * @package Automattic\Jetpack\Extensions\Premium_Content |
| 415 | */ |
| 416 | class ExpiredException extends \UnexpectedValueException { } |
| 417 | } |
| 418 | if ( ! class_exists( 'BeforeValidException' ) ) { |
| 419 | /** |
| 420 | * BeforeValidException |
| 421 | * |
| 422 | * @package Automattic\Jetpack\Extensions\Premium_Content |
| 423 | */ |
| 424 | class BeforeValidException extends \UnexpectedValueException { } |
| 425 | } |
| 426 | // phpcs:enable |
| 427 |