friendica/include/diaspora.php

<?php

require_once('include/crypto.php');
require_once('include/items.php');

function diaspora_get_contact_by_handle($uid,$handle) {
	$r = q("SELECT * FROM `contact` WHERE `network` = '%s' AND `uid` = %d AND `addr` = '%s' LIMIT 1",
		dbesc(NETWORK_DIASPORA),
		intval($uid),
		dbesc($handle)
	);
	if($r && count($r))
		return $r[0];
	return false;
}

function find_diaspora_person_by_handle($handle) {
	$r = q("select * from fcontact where network = '%s' and addr = '%s' limit 1",
		dbesc(NETWORK_DIASPORA),
		dbesc($handle)
	);
	if(count($r)) {
		// update record occasionally so it doesn't get stale
		$d = strtotime($r[0]['updated'] . ' +00:00');
		if($d < strtotime('now - 14 days')) {
			q("delete from fcontact where id = %d limit 1",
				intval($r[0]['id'])
			);
		}
		else
			return $r[0];
	}
	require_once('include/Scrape.php');
	$r = probe_url($handle, PROBE_DIASPORA);
	if((count($r)) && ($r['network'] === NETWORK_DIASPORA)) {
		add_fcontact($r);
		return ($r);
	}
	return false;
}


function get_diaspora_key($uri) {
	logger('Fetching diaspora key for: ' . $uri);

	$r = find_diaspora_person_by_handle($uri);
	if($r)
		return $r['pubkey'];
	return '';
}


function diaspora_msg_build($msg,$user,$contact,$prvkey,$pubkey) {
	$a = get_app();

	logger('diaspora_msg_build: ' . $msg, LOGGER_DATA);

	$inner_aes_key = random_string(32);
	$b_inner_aes_key = base64_encode($inner_aes_key);
	$inner_iv = random_string(16);
	$b_inner_iv = base64_encode($inner_iv);

	$outer_aes_key = random_string(32);
	$b_outer_aes_key = base64_encode($outer_aes_key);
	$outer_iv = random_string(16);
	$b_outer_iv = base64_encode($outer_iv);
	
	$handle = 'acct:' . $user['nickname'] . '@' . substr($a->get_baseurl(), strpos($a->get_baseurl(),'://') + 3);

	$padded_data = pkcs5_pad($msg,16);
	$inner_encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $inner_aes_key, $padded_data, MCRYPT_MODE_CBC, $inner_iv);

	$b64_data = base64_encode($inner_encrypted);


	$b64url_data = base64url_encode($b64_data);
	$b64url_stripped = str_replace(array("\n","\r"," ","\t"),array('','','',''),$b64url_data);
    $lines = str_split($b64url_stripped,60);
    $data = implode("\n",$lines);
	$data = $data . (($data[-1] != "\n") ? "\n" : '') ;
	$type = 'application/atom+xml';
	$encoding = 'base64url';
	$alg = 'RSA-SHA256';

	$signable_data = $data  . '.' . base64url_encode($type) . "\n" . '.' 
		. base64url_encode($encoding) . "\n" . '.' . base64url_encode($alg) . "\n";

	$signature = rsa_sign($signable_data,$prvkey);
	$sig = base64url_encode($signature);

$decrypted_header = <<< EOT
<decrypted_header>
  <iv>$b_inner_iv</iv>
  <aes_key>$b_inner_aes_key</aes_key>
  <author>
    <name>{$user['username']}</name>
    <uri>$handle</uri>
  </author>
</decrypted_header>
EOT;

	$decrypted_header = pkcs5_pad($decrypted_header,16);

	$ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $outer_aes_key, $decrypted_header, MCRYPT_MODE_CBC, $outer_iv);

	$outer_json = json_encode(array('iv' => $b_outer_iv,'key' => $b_outer_aes_key));

	$encrypted_outer_key_bundle = '';
	openssl_public_encrypt($outer_json,$encrypted_outer_key_bundle,$pubkey);

	logger('outer_bundle_encrypt: ' . openssl_error_string());
	$b64_encrypted_outer_key_bundle = base64_encode($encrypted_outer_key_bundle);

	logger('outer_bundle: ' . $b64_encrypted_outer_key_bundle . ' key: ' . $pubkey);

	$encrypted_header_json_object = json_encode(array('aes_key' => base64_encode($encrypted_outer_key_bundle), 
		'ciphertext' => base64_encode($ciphertext)));
	$cipher_json = base64_encode($encrypted_header_json_object);

	$encrypted_header = '<encrypted_header>' . $cipher_json . '</encrypted_header>';

$magic_env = <<< EOT
<?xml version='1.0' encoding='UTF-8'?>
<entry xmlns='http://www.w3.org/2005/Atom'>
  $encrypted_header
  <me:env xmlns:me="http://salmon-protocol.org/ns/magic-env">
    <me:encoding>base64url</me:encoding>
    <me:alg>RSA-SHA256</me:alg>
    <me:data type="application/atom+xml">$data</me:data>
    <me:sig>$sig</me:sig>
  </me:env>
</entry>
EOT;

	logger('diaspora_msg_build: magic_env: ' . $magic_env, LOGGER_DATA);
	return $magic_env;

}

/**
 *
 * diaspora_decode($importer,$xml)
 *   array $importer -> from user table
 *   string $xml -> urldecoded Diaspora salmon 
 *
 * Returns array
 * 'message' -> decoded Diaspora XML message
 * 'author' -> author diaspora handle
 * 'key' -> author public key (converted to pkcs#8)
 *
 * Author and key are used elsewhere to save a lookup for verifying replies and likes
 */


function diaspora_decode($importer,$xml) {

	$basedom = parse_xml_string($xml);

	$atom = $basedom->children(NAMESPACE_ATOM1);

	// Diaspora devs: This is kind of sucky - 'encrypted_header' does not belong in the atom namespace

	$encrypted_header = json_decode(base64_decode($atom->encrypted_header));
	
	$encrypted_aes_key_bundle = base64_decode($encrypted_header->aes_key);
	$ciphertext = base64_decode($encrypted_header->ciphertext);

	$outer_key_bundle = '';
	openssl_private_decrypt($encrypted_aes_key_bundle,$outer_key_bundle,$importer['prvkey']);

	$j_outer_key_bundle = json_decode($outer_key_bundle);

	$outer_iv = base64_decode($j_outer_key_bundle->iv);
	$outer_key = base64_decode($j_outer_key_bundle->key);

	$decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $outer_key, $ciphertext, MCRYPT_MODE_CBC, $outer_iv);


	$decrypted = pkcs5_unpad($decrypted);

	/**
	 * $decrypted now contains something like
	 *
	 *  <decrypted_header>
	 *     <iv>8e+G2+ET8l5BPuW0sVTnQw==</iv>
	 *     <aes_key>UvSMb4puPeB14STkcDWq+4QE302Edu15oaprAQSkLKU=</aes_key>
	 *     <author>
	 *       <name>Ryan Hughes</name>
	 *       <uri>acct:galaxor@diaspora.pirateship.org</uri>
	 *     </author>
	 *  </decrypted_header>
	 */

	logger('decrypted: ' . $decrypted);
	$idom = parse_xml_string($decrypted,false);

	$inner_iv = base64_decode($idom->iv);
	$inner_aes_key = base64_decode($idom->aes_key);

	$author_link = str_replace('acct:','',$idom->author->uri);

	$dom = $basedom->children(NAMESPACE_SALMON_ME);

	// figure out where in the DOM tree our data is hiding

	if($dom->provenance->data)
		$base = $dom->provenance;
	elseif($dom->env->data)
		$base = $dom->env;
	elseif($dom->data)
		$base = $dom;
	
	if(! $base) {
		logger('mod-diaspora: unable to locate salmon data in xml ');
		http_status_exit(400);
	}


	// Stash the signature away for now. We have to find their key or it won't be good for anything.
	$signature = base64url_decode($base->sig);

	// unpack the  data

	// strip whitespace so our data element will return to one big base64 blob
	$data = str_replace(array(" ","\t","\r","\n"),array("","","",""),$base->data);

	// Add back the 60 char linefeeds

	// This completely violates the entire principle of salmon magic signatures,
	// which was to have a message signing format that was completely ambivalent to linefeeds 
	// and transport whitespace mangling, and base64 wrapping rules. Guess what? PHP and Ruby 
	// use different linelengths for base64 output. 

    $lines = str_split($data,60);
    $data = implode("\n",$lines);


	// stash away some other stuff for later

	$type = $base->data[0]->attributes()->type[0];
	$keyhash = $base->sig[0]->attributes()->keyhash[0];
	$encoding = $base->encoding;
	$alg = $base->alg;

	// I can't even begin to tell you how sucky this is. Please read the spec.

	$signed_data = $data  . (($data[-1] != "\n") ? "\n" : '') . '.' . base64url_encode($type) . "\n" . '.' . base64url_encode($encoding) . "\n" . '.' . base64url_encode($alg) . "\n";


	// decode the data
	$data = base64url_decode($data);

	// Now pull out the inner encrypted blob

	$inner_encrypted = base64_decode($data);

	$inner_decrypted = 
	$inner_decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $inner_aes_key, $inner_encrypted, MCRYPT_MODE_CBC, $inner_iv);

	$inner_decrypted = pkcs5_unpad($inner_decrypted);

	if(! $author_link) {
		logger('mod-diaspora: Could not retrieve author URI.');
		http_status_exit(400);
	}

	// Once we have the author URI, go to the web and try to find their public key
	// (first this will look it up locally if it is in the fcontact cache)
	// This will also convert diaspora public key from pkcs#1 to pkcs#8

	logger('mod-diaspora: Fetching key for ' . $author_link );
 	$key = get_diaspora_key($author_link);

	if(! $key) {
		logger('mod-diaspora: Could not retrieve author key.');
		http_status_exit(400);
	}

	$verify = rsa_verify($signed_data,$signature,$key);

	if(! $verify) {
		logger('mod-diaspora: Message did not verify. Discarding.');
		http_status_exit(400);
	}

	logger('mod-diaspora: Message verified.');

	return array('message' => $inner_decrypted, 'author' => $author_link, 'key' => $key);

}

	

function diaspora_request($importer,$xml) {

	$sender_handle = unxmlify($xml->sender_handle);
	$recipient_handle = unxmlify($xml->recipient_handle);

	if(! $sender_handle || ! $recipient_handle)
		return;
	 
	$contact = diaspora_get_contact_by_handle($importer['uid'],$sender_handle);


	if($contact) {

		// perhaps we were already sharing with this person. Now they're sharing with us.
		// That makes us friends.

		if($contact['rel'] == CONTACT_IS_FOLLOWER) {
			q("UPDATE `contact` SET `rel` = %d, `writable` = 1 WHERE `id` = %d AND `uid` = %d LIMIT 1",
				intval(CONTACT_IS_FRIEND),
				intval($contact['id']),
				intval($importer['uid'])
			);
		}
		// send notification?
		return;
	}
	
	$ret = find_diaspora_person_by_handle($sender_handle);


	if((! count($ret)) || ($ret['network'] != NETWORK_DIASPORA)) {
		logger('diaspora_request: Cannot resolve diaspora handle ' . $sender_handle . ' for ' . $recipient_handle);
		return;
	}

	$r = q("INSERT INTO `contact` (`uid`, `network`,`addr`,`created`,`url`,`name`,`nick`,`photo`,`pubkey`,`notify`,`poll`,`blocked`,`priority`)
		VALUES ( %d, '%s', '%s', '%s','%s','%s','%s','%s','%s','%s','%s',%d,%d) ",
		intval($importer['uid']),
		dbesc($ret['network']),
		dbesc($ret['addr']),
		datetime_convert(),
		dbesc($ret['url']),