Friendica Communications Platform (please note that this is a clone of the repository at github, issues are handled there) https://friendi.ca
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<?php
/**
* @file src/Protocol/Salmon.php
*/
namespace Friendica\Protocol;
use Friendica\Core\Logger;
use Friendica\Network\Probe;
use Friendica\Util\Crypto;
use Friendica\Util\Network;
use Friendica\Util\Strings;
use Friendica\Util\XML;
/**
* @brief Salmon Protocol class
* The Salmon Protocol is a message exchange protocol running over HTTP designed to decentralize commentary
* and annotations made against newsfeed articles such as blog posts.
*/
class Salmon
{
/**
* @param string $uri Uniform Resource Identifier
* @param string $keyhash encoded key
* @return mixed
* @throws \Friendica\Network\HTTPException\InternalServerErrorException
*/
public static function getKey($uri, $keyhash)
{
$ret = [];
Logger::log('Fetching salmon key for '.$uri);
$arr = Probe::lrdd($uri);
if (is_array($arr)) {
foreach ($arr as $a) {
if ($a['@attributes']['rel'] === 'magic-public-key') {
$ret[] = $a['@attributes']['href'];
}
}
} else {
return '';
}
// We have found at least one key URL
// If it's inline, parse it - otherwise get the key
if (count($ret) > 0) {
for ($x = 0; $x < count($ret); $x ++) {
if (substr($ret[$x], 0, 5) === 'data:') {
if (strstr($ret[$x], ',')) {
$ret[$x] = substr($ret[$x], strpos($ret[$x], ',') + 1);
} else {
$ret[$x] = substr($ret[$x], 5);
}
} elseif (Strings::normaliseLink($ret[$x]) == 'http://') {
$ret[$x] = Network::fetchUrl($ret[$x]);
}
}
}
Logger::log('Key located: ' . print_r($ret, true));
if (count($ret) == 1) {
// We only found one one key so we don't care if the hash matches.
// If it's the wrong key we'll find out soon enough because
// message verification will fail. This also covers some older
// software which don't supply a keyhash. As long as they only
// have one key we'll be right.
return $ret[0];
} else {
foreach ($ret as $a) {
$hash = Strings::base64UrlEncode(hash('sha256', $a));
if ($hash == $keyhash) {
return $a;
}
}
}
return '';
}
/**
* @param array $owner owner
* @param string $url url
* @param string $slap slap
* @return integer
* @throws \Friendica\Network\HTTPException\InternalServerErrorException
*/
public static function slapper($owner, $url, $slap)
{
// does contact have a salmon endpoint?
if (! strlen($url)) {
return;
}
if (! $owner['sprvkey']) {
Logger::log(sprintf("user '%s' (%d) does not have a salmon private key. Send failed.",
$owner['username'], $owner['uid']));
return;
}
Logger::log('slapper called for '.$url.'. Data: ' . $slap);
// create a magic envelope
$data = Strings::base64UrlEncode($slap);
$data_type = 'application/atom+xml';
$encoding = 'base64url';
$algorithm = 'RSA-SHA256';
$keyhash = Strings::base64UrlEncode(hash('sha256', self::salmonKey($owner['spubkey'])), true);
$precomputed = '.' . Strings::base64UrlEncode($data_type) . '.' . Strings::base64UrlEncode($encoding) . '.' . Strings::base64UrlEncode($algorithm);
// GNU Social format
$signature = Strings::base64UrlEncode(Crypto::rsaSign($data . $precomputed, $owner['sprvkey']));
// Compliant format
$signature2 = Strings::base64UrlEncode(Crypto::rsaSign(str_replace('=', '', $data . $precomputed), $owner['sprvkey']));
// Old Status.net format
$signature3 = Strings::base64UrlEncode(Crypto::rsaSign($data, $owner['sprvkey']));
// At first try the non compliant method that works for GNU Social
$xmldata = ["me:env" => ["me:data" => $data,
"@attributes" => ["type" => $data_type],
"me:encoding" => $encoding,
"me:alg" => $algorithm,
"me:sig" => $signature,
"@attributes2" => ["key_id" => $keyhash]]];
$namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
$salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
// slap them
$postResult = Network::post($url, $salmon, [
'Content-type: application/magic-envelope+xml',
'Content-length: ' . strlen($salmon)
]);
$return_code = $postResult->getReturnCode();
// check for success, e.g. 2xx
if ($return_code > 299) {
Logger::log('GNU Social salmon failed. Falling back to compliant mode');
// Now try the compliant mode that normally isn't used for GNU Social
$xmldata = ["me:env" => ["me:data" => $data,
"@attributes" => ["type" => $data_type],
"me:encoding" => $encoding,
"me:alg" => $algorithm,
"me:sig" => $signature2,
"@attributes2" => ["key_id" => $keyhash]]];
$namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
$salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
// slap them
$postResult = Network::post($url, $salmon, [
'Content-type: application/magic-envelope+xml',
'Content-length: ' . strlen($salmon)
]);
$return_code = $postResult->getReturnCode();
}
if ($return_code > 299) {
Logger::log('compliant salmon failed. Falling back to old status.net');
// Last try. This will most likely fail as well.
$xmldata = ["me:env" => ["me:data" => $data,
"@attributes" => ["type" => $data_type],
"me:encoding" => $encoding,
"me:alg" => $algorithm,
"me:sig" => $signature3,
"@attributes2" => ["key_id" => $keyhash]]];
$namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
$salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
// slap them
$postResult = Network::post($url, $salmon, [
'Content-type: application/magic-envelope+xml',
'Content-length: ' . strlen($salmon)]);
$return_code = $postResult->getReturnCode();
}
Logger::log('slapper for '.$url.' returned ' . $return_code);
if (! $return_code) {
return -1;
}
if (($return_code == 503) && (stristr($postResult->getHeader(), 'retry-after'))) {
return -1;
}
return (($return_code >= 200) && ($return_code < 300)) ? 0 : 1;
}
/**
* @param string $pubkey public key
* @return string
* @throws \Exception
*/
public static function salmonKey($pubkey)
{
Crypto::pemToMe($pubkey, $m, $e);
return 'RSA' . '.' . Strings::base64UrlEncode($m, true) . '.' . Strings::base64UrlEncode($e, true);
}
}