PinEntry.php
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PinEntry.php
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	<?php

	/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

	/**
	* Contains a class implementing automatic pinentry for gpg-agent
	*
	* PHP version 5
	*
	* LICENSE:
	*
	* This library is free software; you can redistribute it and/or modify
	* it under the terms of the GNU Lesser General Public License as
	* published by the Free Software Foundation; either version 2.1 of the
	* License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this library; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*
	* @category Encryption
	* @package Crypt_GPG
	* @author Michael Gauthier <mike@silverorange.com>
	* @copyright 2013 silverorange
	* @license http://www.gnu.org/copyleft/lesser.html LGPL License 2.1
	* @version CVS: $Id$
	* @link http://pear.php.net/package/Crypt_GPG
	*/

	/**
	* CLI user-interface and parser.
	*/
	require_once 'Console/CommandLine.php';

	// {{{ class Crypt_GPG_PinEntry

	/**
	* A command-line dummy pinentry program for use with gpg-agent and Crypt_GPG
	*
	* This pinentry receives passphrases through en environment variable and
	* automatically enters the PIN in response to gpg-agent requests. No user-
	* interaction required.
	*
	* Thie pinentry can be run independently for testing and debugging with the
	* following syntax:
	*
	* <pre>
	* Usage:
	* crypt-gpg-pinentry [options]
	*
	* Options:
	* -l log, --log=log Optional location to log pinentry activity.
	* -v, --verbose Sets verbosity level. Use multiples for more detail
	* (e.g. "-vv").
	* -h, --help show this help message and exit
	* --version show the program version and exit
	* </pre>
	*
	* @category Encryption
	* @package Crypt_GPG
	* @author Michael Gauthier <mike@silverorange.com>
	* @copyright 2013 silverorange
	* @license http://www.gnu.org/copyleft/lesser.html LGPL License 2.1
	* @link http://pear.php.net/package/Crypt_GPG
	* @see Crypt_GPG::getKeys()
	*/
	class Crypt_GPG_PinEntry
	{
	// {{{ class constants

	/**
	* Verbosity level for showing no output.
	*/
	const VERBOSITY_NONE = 0;

	/**
	* Verbosity level for showing error output.
	*/
	const VERBOSITY_ERRORS = 1;

	/**
	* Verbosity level for showing all output, including Assuan protocol
	* messages.
	*/
	const VERBOSITY_ALL = 2;

	/**
	* Length of buffer for reading lines from the Assuan server.
	*
	* PHP reads 8192 bytes. If this is set to less than 8192, PHP reads 8192
	* and buffers the rest so we might as well just read 8192.
	*
	* Using values other than 8192 also triggers PHP bugs.
	*
	* @see http://bugs.php.net/bug.php?id=35224
	*/
	const CHUNK_SIZE = 8192;

	// }}}
	// {{{ protected properties

	/**
	* File handle for the input stream
	*
	* @var resource
	*/
	protected $stdin = null;

	/**
	* File handle for the output stream
	*
	* @var resource
	*/
	protected $stdout = null;

	/**
	* File handle for the log file if a log file is used
	*
	* @var resource
	*/
	protected $logFile = null;

	/**
	* Whether or not this pinentry is finished and is exiting
	*
	* @var boolean
	*/
	protected $moribund = false;

	/**
	* Verbosity level
	*
	* One of:
	* - {@link Crypt_GPG_PinEntry::VERBOSITY_NONE},
	* - {@link Crypt_GPG_PinEntry::VERBOSITY_ERRORS}, or
	* - {@link Crypt_GPG_PinEntry::VERBOSITY_ALL}
	*
	* @var integer
	*/
	protected $verbosity = self::VERBOSITY_NONE;

	/**
	* The command-line interface parser for this pinentry
	*
	* @var Console_CommandLine
	*
	* @see Crypt_GPG_PinEntry::getParser()
	*/
	protected $parser = null;

	/**
	* PINs to be entered by this pinentry
	*
	* An indexed array of associative arrays in the form:
	* <code>
	* <?php
	* array(
	* array(
	* 'keyId' => $keyId,
	* 'passphrase' => $passphrase
	* ),
	* ...
	* );
	* ?>
	* </code>
	*
	* This array is parsed from the environment variable
	* <kbd>PINENTRY_USER_DATA</kbd>.
	*
	* @var array
	*
	* @see Crypt_GPG_PinEntry::initPinsFromENV()
	*/
	protected $pins = array();

	/**
	* PINs that have been tried for the current PIN
	*
	* This is an associative array indexed by the key identifier with
	* values being the same as elements in the {@link Crypt_GPG_PinEntry::$pins}
	* array.
	*
	* @var array
	*/
	protected $triedPins = array();

	/**
	* The PIN currently being requested by the Assuan server
	*
	* If set, this is an associative array in the form:
	* <code>
	* <?php
	* array(
	* 'keyId' => $shortKeyId,
	* 'userId' => $userIdString
	* );
	* ?>
	* </code>
	*
	* @var array\|null
	*/
	protected $currentPin = null;

	// }}}
	// {{{ __invoke()

	/**
	* Runs this pinentry
	*
	* @return void
	*/
	public function __invoke()
	{
	$this->parser = $this->getCommandLineParser();

	try {
	$result = $this->parser->parse();

	$this->setVerbosity($result->options['verbose']);
	$this->setLogFilename($result->options['log']);

	$this->connect();
	$this->initPinsFromENV();

	while (($line = fgets($this->stdin, self::CHUNK_SIZE)) !== false) {
	$this->parseCommand(mb_substr($line, 0, -1, '8bit'));
	if ($this->moribund) {
	break;
	}
	}

	$this->disconnect();

	} catch (Console_CommandLineException $e) {
	$this->log($e->getMessage() . PHP_EOL, slf::VERBOSITY_ERRORS);
	exit(1);
	} catch (Exception $e) {
	$this->log($e->getMessage() . PHP_EOL, self::VERBOSITY_ERRORS);
	$this->log($e->getTraceAsString() . PHP_EOL, self::VERBOSITY_ERRORS);
	exit(1);
	}
	}

	// }}}
	// {{{ setVerbosity()

	/**
	* Sets the verbosity of logging for this pinentry
	*
	* Verbosity levels are:
	*
	* - {@link Crypt_GPG_PinEntry::VERBOSITY_NONE} - no logging.
	* - {@link Crypt_GPG_PinEntry::VERBOSITY_ERRORS} - log errors only.
	* - {@link Crypt_GPG_PinEntry::VERBOSITY_ALL} - log everything, including
	* the assuan protocol.
	*
	* @param integer $verbosity the level of verbosity of this pinentry.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	public function setVerbosity($verbosity)
	{
	$this->verbosity = (integer)$verbosity;
	return $this;
	}

	// }}}
	// {{{ setLogFilename()

	/**
	* Sets the log file location
	*
	* @param string $filename the new log filename to use. If an empty string
	* is used, file-based logging is disabled.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	public function setLogFilename($filename)
	{
	if (is_resource($this->logFile)) {
	fflush($this->logFile);
	fclose($this->logFile);
	$this->logFile = null;
	}

	if ($filename != '') {
	if (($this->logFile = fopen($filename, 'w')) === false) {
	$this->log(
	'Unable to open log file "' . $filename . '" '
	. 'for writing.' . PHP_EOL,
	self::VERBOSITY_ERRORS
	);
	exit(1);
	} else {
	stream_set_write_buffer($this->logFile, 0);
	}
	}

	return $this;
	}

	// }}}
	// {{{ getUIXML()

	/**
	* Gets the CLI user-interface definition for this pinentry
	*
	* Detects whether or not this package is PEAR-installed and appropriately
	* locates the XML UI definition.
	*
	* @return string the location of the CLI user-interface definition XML.
	*/
	protected function getUIXML()
	{
	$dir = '@data-dir@' . DIRECTORY_SEPARATOR
	. '@package-name@' . DIRECTORY_SEPARATOR . 'data';

	// Check if we're running directly from a git checkout or if we're
	// running from a PEAR-packaged version.
	if ($dir[0] == '@') {
	$dir = dirname(__FILE__) . DIRECTORY_SEPARATOR . '..'
	. DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR . 'data';
	}

	return $dir . DIRECTORY_SEPARATOR . 'pinentry-cli.xml';
	}

	// }}}
	// {{{ getCommandLineParser()

	/**
	* Gets the CLI parser for this pinentry
	*
	* @return Console_CommandLine the CLI parser for this pinentry.
	*/
	protected function getCommandLineParser()
	{
	return Console_CommandLine::fromXmlFile($this->getUIXML());
	}

	// }}}
	// {{{ log()

	/**
	* Logs a message at the specified verbosity level
	*
	* If a log file is used, the message is written to the log. Otherwise,
	* the message is sent to STDERR.
	*
	* @param string $data the message to log.
	* @param integer $level the verbosity level above which the message should
	* be logged.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function log($data, $level)
	{
	if ($this->verbosity >= $level) {
	if (is_resource($this->logFile)) {
	fwrite($this->logFile, $data);
	fflush($this->logFile);
	} else {
	$this->parser->outputter->stderr($data);
	}
	}

	return $this;
	}

	// }}}
	// {{{ connect()

	/**
	* Connects this pinentry to the assuan server
	*
	* Opens I/O streams and sends initial handshake.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function connect()
	{
	// Binary operations will not work on Windows with PHP < 5.2.6.
	$rb = (version_compare(PHP_VERSION, '5.2.6') < 0) ? 'r' : 'rb';
	$wb = (version_compare(PHP_VERSION, '5.2.6') < 0) ? 'w' : 'wb';

	$this->stdin = fopen('php://stdin', $rb);
	$this->stdout = fopen('php://stdout', $wb);

	if (function_exists('stream_set_read_buffer')) {
	stream_set_read_buffer($this->stdin, 0);
	}
	stream_set_write_buffer($this->stdout, 0);

	// initial handshake
	$this->send($this->getOK('Crypt_GPG pinentry ready and waiting'));

	return $this;
	}

	// }}}
	// {{{ parseCommand()

	/**
	* Parses an assuan command and performs the appropriate action
	*
	* Documentation of the assuan commands for pinentry is limited to
	* non-existent. Most of these commands were taken from the C source code
	* to gpg-agent and pinentry.
	*
	* Additional context was provided by using strace -f when calling the
	* gpg-agent.
	*
	* @param string $line the assuan command line to parse
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function parseCommand($line)
	{
	$this->log('<- ' . $line . PHP_EOL, self::VERBOSITY_ALL);

	$parts = explode(' ', $line, 2);

	$command = $parts[0];

	if (count($parts) === 2) {
	$data = $parts[1];
	} else {
	$data = null;
	}

	switch ($command) {
	case 'SETDESC':
	return $this->sendSetDescription($data);

	case 'SETPROMPT':
	case 'SETERROR':
	case 'SETOK':
	case 'SETNOTOK':
	case 'SETCANCEL':
	case 'SETQUALITYBAR':
	case 'SETQUALITYBAR_TT':
	case 'OPTION':
	return $this->sendNotImplementedOK();

	case 'MESSAGE':
	return $this->sendMessage();

	case 'CONFIRM':
	return $this->sendConfirm();

	case 'GETINFO':
	return $this->sendGetInfo($data);

	case 'GETPIN':
	return $this->sendGetPin($data);

	case 'RESET':
	return $this->sendReset();

	case 'BYE':
	return $this->sendBye();
	}
	}

	// }}}
	// {{{ initPinsFromENV()

	/**
	* Initializes the PINs to be entered by this pinentry from the environment
	* variable PINENTRY_USER_DATA
	*
	* The PINs are parsed from a JSON-encoded string.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function initPinsFromENV()
	{
	if (($userData = getenv('PINENTRY_USER_DATA')) !== false) {
	$pins = json_decode($userData, true);
	if ($pins === null) {
	$this->log(
	'-- failed to parse user data' . PHP_EOL,
	self::VERBOSITY_ERRORS
	);
	} else {
	$this->pins = $pins;
	$this->log(
	'-- got user data [not showing passphrases]' . PHP_EOL,
	self::VERBOSITY_ALL
	);
	}
	}

	return $this;
	}

	// }}}
	// {{{ disconnect()

	/**
	* Disconnects this pinentry from the Assuan server
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function disconnect()
	{
	$this->log('-- disconnecting' . PHP_EOL, self::VERBOSITY_ALL);

	fflush($this->stdout);
	fclose($this->stdout);
	fclose($this->stdin);

	$this->stdin = null;
	$this->stdout = null;

	$this->log('-- disconnected' . PHP_EOL, self::VERBOSITY_ALL);

	if (is_resource($this->logFile)) {
	fflush($this->logFile);
	fclose($this->logFile);
	$this->logFile = null;
	}

	return $this;
	}

	// }}}
	// {{{ sendNotImplementedOK()

	/**
	* Sends an OK response for a not implemented feature
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendNotImplementedOK()
	{
	return $this->send($this->getOK());
	}

	// }}}
	// {{{ sendSetDescription()

	/**
	* Parses the currently requested key identifier and user identifier from
	* the description passed to this pinentry
	*
	* @param string $text the raw description sent from gpg-agent.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendSetDescription($text)
	{
	$text = rawurldecode($text);
	$matches = array();
	// TODO: handle user id with quotation marks
	$exp = '/\n"(.+)"\n.*\sID ([A-Z0-9]+),\n/mu';
	if (preg_match($exp, $text, $matches) === 1) {
	$userId = $matches[1];
	$keyId = $matches[2];

	// only reset tried pins for new requested pin
	if ( $this->currentPin === null
	\|\| $this->currentPin['keyId'] !== $keyId
	) {
	$this->currentPin = array(
	'userId' => $userId,
	'keyId' => $keyId
	);
	$this->triedPins = array();
	$this->log(
	'-- looking for PIN for ' . $keyId . PHP_EOL,
	self::VERBOSITY_ALL
	);
	}
	}

	return $this->send($this->getOK());
	}

	// }}}
	// {{{ sendConfirm()

	/**
	* Tells the assuan server the PIN entry was confirmed (not cancelled)
	* by pressing the fake 'close' button
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendConfirm()
	{
	return $this->sendButtonInfo('close');
	}

	// }}}
	// {{{ sendMessage()

	/**
	* Tells the assuan server that any requested pop-up messages were confirmed
	* by pressing the fake 'close' button
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendMessage()
	{
	return $this->sendButtonInfo('close');
	}

	// }}}
	// {{{ sendButtonInfo()

	/**
	* Sends information about pressed buttons to the assuan server
	*
	* This is used to fake a user-interface for this pinentry.
	*
	* @param string $text the button status to send.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendButtonInfo($text)
	{
	return $this->send('BUTTON_INFO ' . $text . "\n");
	}

	// }}}
	// {{{ sendGetPin()

	/**
	* Sends the PIN value for the currently requested key
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendGetPin()
	{
	$foundPin = '';

	if (is_array($this->currentPin)) {
	$keyIdLength = mb_strlen($this->currentPin['keyId'], '8bit');

	// search for the pin
	foreach ($this->pins as $pin) {
	// only check pins we haven't tried
	if (!isset($this->triedPins[$pin['keyId']])) {

	// get last X characters of key identifier to compare
	$keyId = mb_substr(
	$pin['keyId'],
	-$keyIdLength,
	mb_strlen($pin['keyId'], '8bit'),
	'8bit'
	);

	if ($keyId === $this->currentPin['keyId']) {
	$foundPin = $pin['passphrase'];
	$this->triedPins[$pin['keyId']] = $pin;
	break;
	}
	}
	}
	}

	return $this
	->send($this->getData($foundPin))
	->send($this->getOK());
	}

	// }}}
	// {{{ sendGetInfo()

	/**
	* Sends information about this pinentry
	*
	* @param string $data the information requested by the assuan server.
	* Currently only 'pid' is supported. Other requests
	* return no information.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendGetInfo($data)
	{
	$parts = explode(' ', $data, 2);
	$command = reset($parts);

	switch ($command) {
	case 'pid':
	return $this->sendGetInfoPID();
	default:
	return $this->send($this->getOK());
	}

	return $this;
	}
	// }}}
	// {{{ sendGetInfoPID()

	/**
	* Sends the PID of this pinentry to the assuan server
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendGetInfoPID()
	{
	return $this
	->send($this->getData(getmypid()))
	->send($this->getOK());
	}

	// }}}
	// {{{ sendBye()

	/**
	* Flags this pinentry for disconnection and sends an OK response
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendBye()
	{
	$return = $this->send($this->getOK('closing connection'));
	$this->moribund = true;
	return $return;
	}

	// }}}
	// {{{ sendReset()

	/**
	* Resets this pinentry and sends an OK response
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function sendReset()
	{
	$this->currentPin = null;
	$this->triedPins = array();
	return $this->send($this->getOK());
	}

	// }}}
	// {{{ getOK()

	/**
	* Gets an OK response to send to the assuan server
	*
	* @param string $data an optional message to include with the OK response.
	*
	* @return string the OK response.
	*/
	protected function getOK($data = null)
	{
	$return = 'OK';

	if ($data) {
	$return .= ' ' . $data;
	}

	return $return . "\n";
	}

	// }}}
	// {{{ getData()

	/**
	* Gets data ready to send to the assuan server
	*
	* Data is appropriately escaped and long lines are wrapped.
	*
	* @param string $data the data to send to the assuan server.
	*
	* @return string the properly escaped, formatted data.
	*
	* @see http://www.gnupg.org/documentation/manuals/assuan/Server-responses.html
	*/
	protected function getData($data)
	{
	// Escape data. Only %, \n and \r need to be escaped but other
	// values are allowed to be escaped. See
	// http://www.gnupg.org/documentation/manuals/assuan/Server-responses.html
	$data = rawurlencode($data);
	$data = $this->getWordWrappedData($data, 'D');
	return $data;
	}

	// }}}
	// {{{ getComment()

	/**
	* Gets a comment ready to send to the assuan server
	*
	* @param string $data the comment to send to the assuan server.
	*
	* @return string the properly formatted comment.
	*
	* @see http://www.gnupg.org/documentation/manuals/assuan/Server-responses.html
	*/
	protected function getComment($data)
	{
	return $this->getWordWrappedData($data, '#');
	}

	// }}}
	// {{{ getWordWrappedData()

	/**
	* Wraps strings at 1,000 bytes without splitting UTF-8 multibyte
	* characters
	*
	* Each line is prepended with the specified line prefix. Wrapped lines
	* are automatically appended with \ characters.
	*
	* Protocol strings are UTF-8 but maximum line length is 1,000 bytes.
	* <kbd>mb_strcut()</kbd> is used so we can limit line length by bytes
	* and not split characters across multiple lines.
	*
	* @param string $data the data to wrap.
	* @param string $prefix a single character to use as the line prefix. For
	* example, 'D' or '#'.
	*
	* @return string the word-wrapped, prefixed string.
	*
	* @see http://www.gnupg.org/documentation/manuals/assuan/Server-responses.html
	*/
	protected function getWordWrappedData($data, $prefix)
	{
	$lines = array();

	do {
	if (mb_strlen($data, '8bit') > 997) {
	$line = $prefix . ' ' . mb_strcut($data, 0, 996, 'utf-8') . "\\\n";
	$lines[] = $line;
	$lineLength = mb_strlen($line, '8bit') - 1;
	$dataLength = mb_substr($data, '8bit');
	$data = mb_substr(
	$data,
	$lineLength,
	$dataLength - $lineLength,
	'8bit'
	);
	} else {
	$lines[] = $prefix . ' ' . $data . "\n";
	$data = '';
	}
	} while ($data != '');

	return implode('', $lines);
	}

	// }}}
	// {{{ send()

	/**
	* Sends raw data to the assuan server
	*
	* @param string $data the data to send.
	*
	* @return Crypt_GPG_PinEntry the current object, for fluent interface.
	*/
	protected function send($data)
	{
	$this->log('-> ' . $data, self::VERBOSITY_ALL);
	fwrite($this->stdout, $data);
	fflush($this->stdout);
	return $this;
	}

	// }}}
	}

	// }}}

	?>

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