| 1 |
<?php |
| 2 |
/** |
| 3 |
* Signature class file. |
| 4 |
* |
| 5 |
* @package Activitypub |
| 6 |
*/ |
| 7 |
|
| 8 |
namespace Activitypub; |
| 9 |
|
| 10 |
use Activitypub\Collection\Actors; |
| 11 |
use Activitypub\Collection\Remote_Actors; |
| 12 |
use Activitypub\Signature\Http_Message_Signature; |
| 13 |
use Activitypub\Signature\Http_Signature_Draft; |
| 14 |
|
| 15 |
/** |
| 16 |
* ActivityPub Signature Class. |
| 17 |
* |
| 18 |
* @author Matthias Pfefferle |
| 19 |
* @author Django Doucet |
| 20 |
*/ |
| 21 |
class Signature { |
| 22 |
|
| 23 |
/** |
| 24 |
* Initialize the class. |
| 25 |
*/ |
| 26 |
public static function init() { |
| 27 |
\add_filter( 'http_request_args', array( self::class, 'sign_request' ), 0, 2 ); // Ahead of all other filters, so signature is set. |
| 28 |
\add_filter( 'http_response', array( self::class, 'maybe_double_knock' ), 10, 3 ); |
| 29 |
} |
| 30 |
|
| 31 |
/** |
| 32 |
* Sign an HTTP Request. |
| 33 |
* |
| 34 |
* @param array $args An array of HTTP request arguments. |
| 35 |
* @param string $url The request URL. |
| 36 |
* |
| 37 |
* @return array Request arguments with signature headers. |
| 38 |
*/ |
| 39 |
public static function sign_request( $args, $url ) { |
| 40 |
// Bail if there's nothing to sign with. |
| 41 |
if ( ! isset( $args['key_id'], $args['private_key'] ) ) { |
| 42 |
return $args; |
| 43 |
} |
| 44 |
|
| 45 |
if ( '1' === \get_option( 'activitypub_rfc9421_signature' ) && self::could_support_rfc9421( $url ) ) { |
| 46 |
$signature = new Http_Message_Signature(); |
| 47 |
} else { |
| 48 |
$signature = new Http_Signature_Draft(); |
| 49 |
} |
| 50 |
|
| 51 |
return $signature->sign( $args, $url ); |
| 52 |
} |
| 53 |
|
| 54 |
/** |
| 55 |
* Verifies the http signatures |
| 56 |
* |
| 57 |
* @param \WP_REST_Request|array $request The request object or $_SERVER array. |
| 58 |
* |
| 59 |
* @return bool|\WP_Error A boolean or WP_Error. |
| 60 |
*/ |
| 61 |
public static function verify_http_signature( $request ) { |
| 62 |
if ( is_object( $request ) ) { // REST Request object. |
| 63 |
$body = $request->get_body(); |
| 64 |
$headers = $request->get_headers(); |
| 65 |
$headers['(request-target)'][0] = strtolower( $request->get_method() ) . ' ' . self::get_route( $request ); |
| 66 |
} else { |
| 67 |
$headers = self::format_server_request( $request ); |
| 68 |
$headers['(request-target)'][0] = strtolower( $headers['request_method'][0] ) . ' ' . $headers['request_uri'][0]; |
| 69 |
} |
| 70 |
|
| 71 |
$signature = isset( $headers['signature_input'] ) ? new Http_Message_Signature() : new Http_Signature_Draft(); |
| 72 |
|
| 73 |
return $signature->verify( $headers, $body ?? null ); |
| 74 |
} |
| 75 |
|
| 76 |
/** |
| 77 |
* If a request with RFC-9421 signature fails, we try again with the Draft Cavage signature. |
| 78 |
* |
| 79 |
* @param array $response HTTP response. |
| 80 |
* @param array $args HTTP request arguments. |
| 81 |
* @param string $url The request URL. |
| 82 |
* |
| 83 |
* @return array The HTTP response. |
| 84 |
*/ |
| 85 |
public static function maybe_double_knock( $response, $args, $url ) { |
| 86 |
// Bail if it didn't use an RFC-9421 signature or there's nothing to sign with. |
| 87 |
if ( ! isset( $args['key_id'], $args['private_key'], $args['headers']['Signature-Input'] ) ) { |
| 88 |
return $response; |
| 89 |
} |
| 90 |
|
| 91 |
$response_code = \wp_remote_retrieve_response_code( $response ); |
| 92 |
|
| 93 |
// Fall back to Draft Cavage signature for any 4xx responses. |
| 94 |
if ( $response_code >= 400 && $response_code < 500 ) { |
| 95 |
unset( $args['headers']['Signature'], $args['headers']['Signature-Input'], $args['headers']['Content-Digest'] ); |
| 96 |
self::rfc9421_add_unsupported_host( $url ); |
| 97 |
|
| 98 |
$args = ( new Http_Signature_Draft() )->sign( $args, $url ); |
| 99 |
$response = \wp_safe_remote_request( $url, $args ); |
| 100 |
} |
| 101 |
|
| 102 |
return $response; |
| 103 |
} |
| 104 |
|
| 105 |
/** |
| 106 |
* Formats the $_SERVER to resemble the WP_REST_REQUEST array, |
| 107 |
* for use with verify_http_signature(). |
| 108 |
* |
| 109 |
* @param array $server The $_SERVER array. |
| 110 |
* |
| 111 |
* @return array $request The formatted request array. |
| 112 |
*/ |
| 113 |
public static function format_server_request( $server ) { |
| 114 |
$headers = array(); |
| 115 |
|
| 116 |
foreach ( $server as $key => $value ) { |
| 117 |
$key = \str_replace( 'http_', '', \strtolower( $key ) ); |
| 118 |
$headers[ $key ][] = \wp_unslash( $value ); |
| 119 |
|
| 120 |
} |
| 121 |
|
| 122 |
return $headers; |
| 123 |
} |
| 124 |
|
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/** |
| 126 |
* Returns route. |
| 127 |
* |
| 128 |
* @param \WP_REST_Request $request The request object. |
| 129 |
* |
| 130 |
* @return string |
| 131 |
*/ |
| 132 |
private static function get_route( $request ) { |
| 133 |
// Check if the route starts with "index.php". |
| 134 |
if ( str_starts_with( $request->get_route(), '/index.php' ) || ! rest_get_url_prefix() ) { |
| 135 |
$route = $request->get_route(); |
| 136 |
} else { |
| 137 |
$route = '/' . rest_get_url_prefix() . '/' . ltrim( $request->get_route(), '/' ); |
| 138 |
} |
| 139 |
|
| 140 |
// Fix route for subdirectory installations. |
| 141 |
$path = \wp_parse_url( \get_home_url(), PHP_URL_PATH ); |
| 142 |
|
| 143 |
if ( \is_string( $path ) ) { |
| 144 |
$path = trim( $path, '/' ); |
| 145 |
} |
| 146 |
|
| 147 |
if ( $path ) { |
| 148 |
$route = '/' . $path . $route; |
| 149 |
} |
| 150 |
|
| 151 |
return $route; |
| 152 |
} |
| 153 |
|
| 154 |
/** |
| 155 |
* Check if RFC-9421 signature could be supported. |
| 156 |
* |
| 157 |
* @param string $url The URL to check. |
| 158 |
* |
| 159 |
* @return bool True, if RFC-9421 signature could be supported, false otherwise. |
| 160 |
*/ |
| 161 |
private static function could_support_rfc9421( $url ) { |
| 162 |
$host = \wp_parse_url( $url, \PHP_URL_HOST ); |
| 163 |
$list = \get_option( 'activitypub_rfc9421_unsupported', array() ); |
| 164 |
|
| 165 |
if ( isset( $list[ $host ] ) ) { |
| 166 |
if ( $list[ $host ] > \time() ) { |
| 167 |
return false; |
| 168 |
} |
| 169 |
|
| 170 |
unset( $list[ $host ] ); |
| 171 |
\update_option( 'activitypub_rfc9421_unsupported', $list ); |
| 172 |
} |
| 173 |
|
| 174 |
return true; |
| 175 |
} |
| 176 |
|
| 177 |
/** |
| 178 |
* Set RFC-9421 signature unsupported for a given host. |
| 179 |
* |
| 180 |
* @param string $url The URL to set. |
| 181 |
*/ |
| 182 |
private static function rfc9421_add_unsupported_host( $url ) { |
| 183 |
$list = \get_option( 'activitypub_rfc9421_unsupported', array() ); |
| 184 |
$host = \wp_parse_url( $url, \PHP_URL_HOST ); |
| 185 |
|
| 186 |
$list[ $host ] = \time() + MONTH_IN_SECONDS; |
| 187 |
\update_option( 'activitypub_rfc9421_unsupported', $list, false ); |
| 188 |
} |
| 189 |
|
| 190 |
/** |
| 191 |
* Return the public key for a given user. |
| 192 |
* |
| 193 |
* @deprecated 7.0.0 Use {@see Actors::get_public_key()}. |
| 194 |
* |
| 195 |
* @param int $user_id The WordPress User ID. |
| 196 |
* @param bool $force Optional. Force the generation of a new key pair. Default false. |
| 197 |
* |
| 198 |
* @return string The public key. |
| 199 |
*/ |
| 200 |
public static function get_public_key_for( $user_id, $force = false ) { |
| 201 |
\_deprecated_function( __METHOD__, '7.0.0', 'Activitypub\Collection\Actors::get_public_key' ); |
| 202 |
|
| 203 |
return Actors::get_public_key( $user_id, $force ); |
| 204 |
} |
| 205 |
|
| 206 |
/** |
| 207 |
* Return the private key for a given user. |
| 208 |
* |
| 209 |
* @deprecated 7.0.0 Use {@see Actors::get_private_key()}. |
| 210 |
* |
| 211 |
* @param int $user_id The WordPress User ID. |
| 212 |
* @param bool $force Optional. Force the generation of a new key pair. Default false. |
| 213 |
* |
| 214 |
* @return string The private key. |
| 215 |
*/ |
| 216 |
public static function get_private_key_for( $user_id, $force = false ) { |
| 217 |
\_deprecated_function( __METHOD__, '7.0.0', 'Activitypub\Collection\Actors::get_private_key' ); |
| 218 |
|
| 219 |
return Actors::get_private_key( $user_id, $force ); |
| 220 |
} |
| 221 |
|
| 222 |
/** |
| 223 |
* Return the key pair for a given user. |
| 224 |
* |
| 225 |
* @deprecated 7.0.0 Use {@see Actors::get_keypair()}. |
| 226 |
* |
| 227 |
* @param int $user_id The WordPress User ID. |
| 228 |
* |
| 229 |
* @return array The key pair. |
| 230 |
*/ |
| 231 |
public static function get_keypair_for( $user_id ) { |
| 232 |
\_deprecated_function( __METHOD__, '7.0.0', 'Activitypub\Collection\Actors::get_keypair' ); |
| 233 |
|
| 234 |
return Actors::get_keypair( $user_id ); |
| 235 |
} |
| 236 |
|
| 237 |
/** |
| 238 |
* Get public key from key_id. |
| 239 |
* |
| 240 |
* @deprecated 7.4.0 Use {@see Remote_Actors::get_public_key()}. |
| 241 |
* |
| 242 |
* @param string $key_id The URL to the public key. |
| 243 |
* |
| 244 |
* @return resource|\WP_Error The public key resource or WP_Error. |
| 245 |
*/ |
| 246 |
public static function get_remote_key( $key_id ) { |
| 247 |
\_deprecated_function( __METHOD__, '7.4.0', 'Activitypub\Collection\Remote_Actors::get_public_key()' ); |
| 248 |
|
| 249 |
return Remote_Actors::get_public_key( $key_id ); |
| 250 |
} |
| 251 |
|
| 252 |
/** |
| 253 |
* Generates the Signature for an HTTP Request. |
| 254 |
* |
| 255 |
* @deprecated 7.0.0 Use {@see Signature::sign_request()}. |
| 256 |
* |
| 257 |
* @param int $user_id The WordPress User ID. |
| 258 |
* @param string $http_method The HTTP method. |
| 259 |
* @param string $url The URL to send the request to. |
| 260 |
* @param string $date The date the request is sent. |
| 261 |
* @param string $digest Optional. The digest of the request body. Default null. |
| 262 |
* |
| 263 |
* @return string The signature. |
| 264 |
*/ |
| 265 |
public static function generate_signature( $user_id, $http_method, $url, $date, $digest = null ) { |
| 266 |
\_deprecated_function( __METHOD__, '7.0.0', self::class . '::sign_request()' ); |
| 267 |
|
| 268 |
$user = Actors::get_by_id( $user_id ); |
| 269 |
$key = Actors::get_private_key( $user_id ); |
| 270 |
|
| 271 |
$url_parts = \wp_parse_url( $url ); |
| 272 |
|
| 273 |
$host = $url_parts['host']; |
| 274 |
$path = '/'; |
| 275 |
|
| 276 |
// Add path. |
| 277 |
if ( ! empty( $url_parts['path'] ) ) { |
| 278 |
$path = $url_parts['path']; |
| 279 |
} |
| 280 |
|
| 281 |
// Add query. |
| 282 |
if ( ! empty( $url_parts['query'] ) ) { |
| 283 |
$path .= '?' . $url_parts['query']; |
| 284 |
} |
| 285 |
|
| 286 |
$http_method = \strtolower( $http_method ); |
| 287 |
|
| 288 |
if ( ! empty( $digest ) ) { |
| 289 |
$signed_string = "(request-target): $http_method $path\nhost: $host\ndate: $date\ndigest: $digest"; |
| 290 |
} else { |
| 291 |
$signed_string = "(request-target): $http_method $path\nhost: $host\ndate: $date"; |
| 292 |
} |
| 293 |
|
| 294 |
$signature = null; |
| 295 |
\openssl_sign( $signed_string, $signature, $key, \OPENSSL_ALGO_SHA256 ); |
| 296 |
$signature = \base64_encode( $signature ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode |
| 297 |
|
| 298 |
$key_id = $user->get_id() . '#main-key'; |
| 299 |
|
| 300 |
if ( ! empty( $digest ) ) { |
| 301 |
return \sprintf( 'keyId="%s",algorithm="rsa-sha256",headers="(request-target) host date digest",signature="%s"', $key_id, $signature ); |
| 302 |
} else { |
| 303 |
return \sprintf( 'keyId="%s",algorithm="rsa-sha256",headers="(request-target) host date",signature="%s"', $key_id, $signature ); |
| 304 |
} |
| 305 |
} |
| 306 |
|
| 307 |
/** |
| 308 |
* Gets the signature algorithm from the signature header. |
| 309 |
* |
| 310 |
* @deprecated 7.0.0 Use {@see Signature::verify()}. |
| 311 |
* |
| 312 |
* @param array $signature_block The signature block. |
| 313 |
* |
| 314 |
* @return string|bool The signature algorithm or false if not found. |
| 315 |
*/ |
| 316 |
public static function get_signature_algorithm( $signature_block ) { // phpcs:ignore |
| 317 |
\_deprecated_function( __METHOD__, '7.0.0', self::class . '::verify' ); |
| 318 |
|
| 319 |
if ( ! empty( $signature_block['algorithm'] ) ) { |
| 320 |
switch ( $signature_block['algorithm'] ) { |
| 321 |
case 'rsa-sha-512': |
| 322 |
return 'sha512'; // hs2019 https://datatracker.ietf.org/doc/html/draft-cavage-http-signatures-12. |
| 323 |
default: |
| 324 |
return 'sha256'; |
| 325 |
} |
| 326 |
} |
| 327 |
|
| 328 |
return false; |
| 329 |
} |
| 330 |
|
| 331 |
/** |
| 332 |
* Parses the Signature header. |
| 333 |
* |
| 334 |
* @deprecated 7.0.0 Use {@see Signature::verify()}. |
| 335 |
* |
| 336 |
* @param string $signature The signature header. |
| 337 |
* |
| 338 |
* @return array Signature parts. |
| 339 |
*/ |
| 340 |
public static function parse_signature_header( $signature ) { // phpcs:ignore |
| 341 |
\_deprecated_function( __METHOD__, '7.0.0', self::class . '::verify' ); |
| 342 |
|
| 343 |
$parsed_header = array(); |
| 344 |
$matches = array(); |
| 345 |
|
| 346 |
if ( \preg_match( '/keyId="(.*?)"/ism', $signature, $matches ) ) { |
| 347 |
$parsed_header['keyId'] = trim( $matches[1] ); |
| 348 |
} |
| 349 |
if ( \preg_match( '/created=["|\']*([0-9]*)["|\']*/ism', $signature, $matches ) ) { |
| 350 |
$parsed_header['(created)'] = trim( $matches[1] ); |
| 351 |
} |
| 352 |
if ( \preg_match( '/expires=["|\']*([0-9]*)["|\']*/ism', $signature, $matches ) ) { |
| 353 |
$parsed_header['(expires)'] = trim( $matches[1] ); |
| 354 |
} |
| 355 |
if ( \preg_match( '/algorithm="(.*?)"/ism', $signature, $matches ) ) { |
| 356 |
$parsed_header['algorithm'] = trim( $matches[1] ); |
| 357 |
} |
| 358 |
if ( \preg_match( '/headers="(.*?)"/ism', $signature, $matches ) ) { |
| 359 |
$parsed_header['headers'] = \explode( ' ', trim( $matches[1] ) ); |
| 360 |
} |
| 361 |
if ( \preg_match( '/signature="(.*?)"/ism', $signature, $matches ) ) { |
| 362 |
$parsed_header['signature'] = \base64_decode( preg_replace( '/\s+/', '', trim( $matches[1] ) ) ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_decode |
| 363 |
} |
| 364 |
|
| 365 |
if ( empty( $parsed_header['headers'] ) ) { |
| 366 |
$parsed_header['headers'] = array( 'date' ); |
| 367 |
} |
| 368 |
|
| 369 |
return $parsed_header; |
| 370 |
} |
| 371 |
|
| 372 |
/** |
| 373 |
* Gets the header data from the included pseudo headers. |
| 374 |
* |
| 375 |
* @deprecated 7.0.0 Use {@see Signature::verify()}. |
| 376 |
* |
| 377 |
* @param array $signed_headers The signed headers. |
| 378 |
* @param array $signature_block The signature block. |
| 379 |
* @param array $headers The HTTP headers. |
| 380 |
* |
| 381 |
* @return string signed headers for comparison |
| 382 |
*/ |
| 383 |
public static function get_signed_data( $signed_headers, $signature_block, $headers ) { // phpcs:ignore |
| 384 |
\_deprecated_function( __METHOD__, '7.0.0', self::class . '::verify' ); |
| 385 |
|
| 386 |
$signed_data = ''; |
| 387 |
|
| 388 |
// This also verifies time-based values by returning false if any of these are out of range. |
| 389 |
foreach ( $signed_headers as $header ) { |
| 390 |
if ( 'host' === $header ) { |
| 391 |
if ( isset( $headers['x_original_host'] ) ) { |
| 392 |
$signed_data .= $header . ': ' . $headers['x_original_host'][0] . "\n"; |
| 393 |
continue; |
| 394 |
} |
| 395 |
} |
| 396 |
if ( '(request-target)' === $header ) { |
| 397 |
$signed_data .= $header . ': ' . $headers[ $header ][0] . "\n"; |
| 398 |
continue; |
| 399 |
} |
| 400 |
if ( str_contains( $header, '-' ) ) { |
| 401 |
$signed_data .= $header . ': ' . $headers[ str_replace( '-', '_', $header ) ][0] . "\n"; |
| 402 |
continue; |
| 403 |
} |
| 404 |
if ( '(created)' === $header ) { |
| 405 |
if ( ! empty( $signature_block['(created)'] ) && \intval( $signature_block['(created)'] ) > \time() ) { |
| 406 |
// Created in the future. |
| 407 |
return false; |
| 408 |
} |
| 409 |
|
| 410 |
if ( ! array_key_exists( '(created)', $headers ) ) { |
| 411 |
$signed_data .= $header . ': ' . $signature_block['(created)'] . "\n"; |
| 412 |
continue; |
| 413 |
} |
| 414 |
} |
| 415 |
if ( '(expires)' === $header ) { |
| 416 |
if ( ! empty( $signature_block['(expires)'] ) && \intval( $signature_block['(expires)'] ) < \time() ) { |
| 417 |
// Expired in the past. |
| 418 |
return false; |
| 419 |
} |
| 420 |
|
| 421 |
if ( ! array_key_exists( '(expires)', $headers ) ) { |
| 422 |
$signed_data .= $header . ': ' . $signature_block['(expires)'] . "\n"; |
| 423 |
continue; |
| 424 |
} |
| 425 |
} |
| 426 |
if ( 'date' === $header ) { |
| 427 |
// A signed `date` header with no value must fail closed, otherwise the time-window check is skipped. |
| 428 |
if ( empty( $headers[ $header ][0] ) ) { |
| 429 |
return false; |
| 430 |
} |
| 431 |
|
| 432 |
// date_create() returns false on malformed input; new DateTime() would instead throw. |
| 433 |
$d = \date_create( $headers[ $header ][0], new \DateTimeZone( 'UTC' ) ); |
| 434 |
if ( false === $d ) { |
| 435 |
return false; |
| 436 |
} |
| 437 |
$d->setTimeZone( new \DateTimeZone( 'UTC' ) ); |
| 438 |
$c = (int) $d->format( 'U' ); |
| 439 |
|
| 440 |
// Match the past-skew of the maintained Http_Signature_Draft verifier (1 hour); use its 5-minute future allowance. |
| 441 |
$now = \time(); |
| 442 |
$d_plus = $now + ( 5 * MINUTE_IN_SECONDS ); |
| 443 |
$d_minus = $now - HOUR_IN_SECONDS; |
| 444 |
|
| 445 |
if ( $c > $d_plus || $c < $d_minus ) { |
| 446 |
// Time out of range. |
| 447 |
return false; |
| 448 |
} |
| 449 |
} |
| 450 |
|
| 451 |
if ( ! empty( $headers[ $header ][0] ) ) { |
| 452 |
$signed_data .= $header . ': ' . $headers[ $header ][0] . "\n"; |
| 453 |
} |
| 454 |
} |
| 455 |
|
| 456 |
return \rtrim( $signed_data, "\n" ); |
| 457 |
} |
| 458 |
|
| 459 |
/** |
| 460 |
* Generates the digest for an HTTP Request. |
| 461 |
* |
| 462 |
* @deprecated 7.0.0 Use {@see Signature::sign_request()}. |
| 463 |
* |
| 464 |
* @param string $body The body of the request. |
| 465 |
* |
| 466 |
* @return string The digest. |
| 467 |
*/ |
| 468 |
public static function generate_digest( $body ) { |
| 469 |
\_deprecated_function( __METHOD__, '7.0.0', self::class . '::sign_request' ); |
| 470 |
|
| 471 |
$digest = \base64_encode( \hash( 'sha256', $body, true ) ); // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode |
| 472 |
return "SHA-256=$digest"; |
| 473 |
} |
| 474 |
|
| 475 |
/** |
| 476 |
* Compute the collection digest for a specific instance. |
| 477 |
* |
| 478 |
* Implements FEP-8fcf: Followers collection synchronization. |
| 479 |
* The digest is created by XORing together the individual SHA256 digests |
| 480 |
* of each follower's ID. |
| 481 |
* |
| 482 |
* @see https://codeberg.org/fediverse/fep/src/branch/main/fep/8fcf/fep-8fcf.md |
| 483 |
* |
| 484 |
* @param array $collection The user ID whose followers to compute. |
| 485 |
* |
| 486 |
* @return string|false The hex-encoded digest, or false if no followers. |
| 487 |
*/ |
| 488 |
public static function get_collection_digest( $collection ) { |
| 489 |
if ( empty( $collection ) || ! is_array( $collection ) ) { |
| 490 |
return false; |
| 491 |
} |
| 492 |
|
| 493 |
// Initialize with zeros (64 hex chars = 32 bytes = 256 bits). |
| 494 |
$digest = str_repeat( '0', 64 ); |
| 495 |
|
| 496 |
foreach ( $collection as $item ) { |
| 497 |
// Compute SHA256 hash of the follower ID. |
| 498 |
$hash = hash( 'sha256', $item ); |
| 499 |
|
| 500 |
// XOR the hash with the running digest. |
| 501 |
$digest = self::xor_hex_strings( $digest, $hash ); |
| 502 |
} |
| 503 |
|
| 504 |
return $digest; |
| 505 |
} |
| 506 |
|
| 507 |
/** |
| 508 |
* XOR two hexadecimal strings. |
| 509 |
* |
| 510 |
* Used for FEP-8fcf digest computation. |
| 511 |
* |
| 512 |
* @param string $hex1 First hex string. |
| 513 |
* @param string $hex2 Second hex string. |
| 514 |
* |
| 515 |
* @return string The XORed result as a hex string. |
| 516 |
*/ |
| 517 |
public static function xor_hex_strings( $hex1, $hex2 ) { |
| 518 |
$result = ''; |
| 519 |
|
| 520 |
// Ensure both strings are the same length (should be 64 chars for SHA256). |
| 521 |
$length = \max( \strlen( $hex1 ), \strlen( $hex2 ) ); |
| 522 |
$hex1 = \str_pad( $hex1, $length, '0', STR_PAD_LEFT ); |
| 523 |
$hex2 = \str_pad( $hex2, $length, '0', STR_PAD_LEFT ); |
| 524 |
|
| 525 |
// XOR each pair of hex digits. |
| 526 |
for ( $i = 0; $i < $length; $i += 2 ) { |
| 527 |
$byte1 = \hexdec( \substr( $hex1, $i, 2 ) ); |
| 528 |
$byte2 = \hexdec( \substr( $hex2, $i, 2 ) ); |
| 529 |
$result .= \str_pad( \dechex( $byte1 ^ $byte2 ), 2, '0', STR_PAD_LEFT ); |
| 530 |
} |
| 531 |
|
| 532 |
return $result; |
| 533 |
} |
| 534 |
|
| 535 |
/** |
| 536 |
* Parse a Collection-Synchronization header (FEP-8fcf). |
| 537 |
* |
| 538 |
* Parses the signature-style format used by the Collection-Synchronization header. |
| 539 |
* |
| 540 |
* @see https://codeberg.org/fediverse/fep/src/branch/main/fep/8fcf/fep-8fcf.md |
| 541 |
* |
| 542 |
* @param string $header The header value. |
| 543 |
* |
| 544 |
* @return array|false Array with parsed parameters (collectionId, url, digest), or false on failure. |
| 545 |
*/ |
| 546 |
public static function parse_collection_sync_header( $header ) { |
| 547 |
if ( empty( $header ) ) { |
| 548 |
return false; |
| 549 |
} |
| 550 |
|
| 551 |
// Parse the signature-style format: key="value", key="value". |
| 552 |
$params = array(); |
| 553 |
|
| 554 |
if ( \preg_match_all( '/(\w+)="([^"]*)"/', $header, $matches, PREG_SET_ORDER ) ) { |
| 555 |
foreach ( $matches as $match ) { |
| 556 |
$params[ $match[1] ] = $match[2]; |
| 557 |
} |
| 558 |
} |
| 559 |
|
| 560 |
// Validate required fields for FEP-8fcf. |
| 561 |
if ( empty( $params['collectionId'] ) || empty( $params['url'] ) || empty( $params['digest'] ) ) { |
| 562 |
return false; |
| 563 |
} |
| 564 |
|
| 565 |
return $params; |
| 566 |
} |
| 567 |
} |
| 568 |
|
