<?php

/** Options from Wordpress (stored in database) **/

// You should normally not change any of these values. Use the Wordpress backend instead.

$rewritebase = repress_make_rewrite_base();
$remoteservers = json_decode( get_option('repress_remoteservers'), TRUE );
$agentstring = "RePress plugin/" . plugin_get_version() . " (PHP " . phpversion() . " streamer) - please read https://all4xs.net";
if (get_option('repress_push_post') == 'yes') {
    $doPosts = true;
} else {
    $doPosts = false;
}
if (get_option('repress_push_cookie') == 'yes') {
    $doCookies = true;
} else {
    $doCookies = false;
}
if (get_option('repress_secret') !== '') {
    $secret = get_option('repress_secret');
} else {
    $secret = 'repress';        // make something up if you want to support hashed cookies
}
if (get_option('repress_use_hashes') == 'yes') {
    $useHashes = true;
} else {
    $useHashes = false;
}
$acceptCookies = array ( '' );

/** Debugging opions **/

$GLOBALS['proxydebug'] = false;     // debugging? will dump all output to flat file.
$GLOBALS['proxydebugfile'] = '/tmp/repress.module.debug.log';
error_reporting(0);

/** Detect WordPress permalink structure **/
if ( get_option('permalink_structure') == '' ) {

    // There is no permalink structure. We will do nothing.

} else {

/*** Proxy code begins here. ***/

// Include dependencies

// proxyhelp requirement
require_once('proxyhelp/proxify_html_resource.php');
// domain functions
require_once('domains.php');

/** Attempt to destroy cookies above RePress base **/

require_once("emptycookieredirect.php");

/** Process request **/

if (!isset($_SERVER['REQUEST_URI']) || $_SERVER['REQUEST_URI'] == '') {
    logline("proxy, called without request. exiting");
    exit;
}

logline("proxy, intercepted request: ", $_SERVER['REQUEST_URI']);

$hit = false; $extra = ''; $strippedRepress = ''; $remoteserver = ''; $abbreviation = ''; $text = false;

$len = strlen($rewritebase);
if (strncmp($_SERVER['REQUEST_URI'], $rewritebase, $len) == 0) {

    logline("proxy, our rewritebase / in url. Seems promising at first sight.");

    // strip repress/ part

    if (preg_match("/#\//", $rewritebase)) { continue; }
    $strippedRepress = preg_replace("#^" . $rewritebase . "[\/]?#", "", $_SERVER['REQUEST_URI']);

    // strip everything after first slash

    $stripped = preg_replace("/\/.*$/", "", $strippedRepress);

    // domain name should be left over, this could be a hash (obfuscated domain name)

    if ($useHashes) {
        logline("proxy, trying to decode the domain name from its hashed value");
        $stripped = rawurldecode($stripped);        // now we have Base64 encoded hash
        logline("proxy, rawurldecode() returns ", $stripped);
        $stripped = repress_get_host_from_hash($stripped, $secret);
        $stripped = rtrim($stripped);
        logline("proxy, decode output = ", $stripped);
    }

    /** Possible hit. Is the domain one we proxy? **/

    if (repress_recognize_host($stripped)) {

        $hit = true; $remoteserver = $stripped;

    }

    if ($hit == false) {
        header('HTTP/1.0 404 Not Found');

        exit;       // close, but no cigar.
    }
}

if ($hit) {

    /// Store the 'abbreviation' of this host, ie. either the hostname or its hash

    if ($useHashes) {
        $abbreviation = repress_obfuscate($remoteserver, $secret);
    } else {
        $abbreviation = $remoteserver;
    }

    logline("proxy, looking for something extra, a path, or query.");

    // now strippedRepress looks something like: wikileaks.org[/][....]

    // if no slashes, no extra
    if (strpos($strippedRepress,'/') == FALSE) {
        $extra = '';
    } else {
        // extra is everything after the first slash
        $extra = preg_replace("/^.*?\//", "", $strippedRepress);

        // and may be obfuscated ..
        // but to make it even more complex. part of this url string can contain GET parameters that were added by the browser
        // as part of a form field for instance, and these will _not_ be obfuscated because we do not rewrite form field IDs in pages

        if ($useHashes && $extra !== '') {

            logline("proxy, we got an extra and we are going to de-obfuscate it, extra = ", $extra);

            logline("proxy, first looking for GET parameters in this string");
            if (preg_match("/^(.*)\?(.*)$/", $extra, $matches)) {
                logline("proxy, it does have 'em, rip apart");
                $extra = rawurldecode($matches[1]);
                logline("proxy, raw decode: ", $extra);
                $extra = repress_get_host_from_hash($extra, $secret);
                logline("proxy, hash decode: ", $extra);
                $extra = rtrim($extra);
                $extra .= '?' . $matches[2];

            } else {
                logline("proxy, nope. Totally obfuscated.");
                $extra = rawurldecode($extra);
                $extra = repress_get_host_from_hash($extra, $secret);
                $extra = rtrim($extra);
            }
            logline("proxy, now it has become ", $extra);
        }
    }

    // try to protect against XSS attacks on Wordpress sessions if running as plugin
    if (function_exists('repress_logout_wordpress_user')) {
        repress_logout_wordpress_user();
    }

    logline("proxy, interpreted a hit as follows:");
    logline("proxy, remoteserver = ", $remoteserver);
    logline("proxy, abbreviation = ", $abbreviation);
    logline("proxy, extra = ", $extra);

    // do we do a POST?

    if ($doPosts && is_array($_POST) && count($_POST) > 0) {
        $requestType = 'POST';
    } else {
        $requestType = 'GET';
    }

    // do we do cookies?

    $cookieHeaders = '';

    if ($doCookies && is_array($_COOKIE) && count($_COOKIE) > 0) {
        foreach ($_COOKIE as $name => $val) {
            $encodeName = rawurlencode($name);
            $encodeVal = rawurlencode($val);
            $cookieHeaders .= "Cookie: $encodeName=$encodeVal\r\n";
        }
    }

    /* Establish streaming connection to the remote server */

    if ($requestType == 'GET') {
        $streamOptions = array(
                      'http'=>array(
                                  'method'=>"GET",
                          'host'=>$remoteserver,
                          'user_agent'=>$agentstring,
                          'header'=>$cookieHeaders
                           )
                      );
    } else {
        $postData = http_build_query($_POST);

        $streamOptions = array(
                      'http'=>array(
                                      'method'=>"POST",
                          'host'=>$remoteserver,
                          'user_agent'=>$agentstring,
                          'header'=>"Content-type: application/x-www-form-urlencoded\r\n" .
                                    "Content-Length: " . strlen($postData) . "\r\n" .
                                $cookieHeaders,
                          'content'=>$postData
                           )
                      );
    }

    $context = stream_context_create($streamOptions);

    logline("proxy, calling build_query function");

    $urlOpen = repress_build_query_url("http://$remoteserver/$extra");

    logline("proxy, open to location ", "'http://$remoteserver/$extra' as '$urlOpen'");

    $handle = fopen($urlOpen, "rb", false, $context);
    if ($handle == FALSE) {
        if (isset($GLOBALS['proxydebug']) && $GLOBALS['proxydebug']) {
            echo("Proxy error to: http://$remoteserver/$extra");
        }
        exit;
    }

    /* Start working on headers */
    $one_byte = fread($handle, 1); // mh_edit this is used to stop the "bug" reported here https://bugs.php.net/bug.php?id=46896 where the responce headers are missing
    $meta = stream_get_meta_data($handle);
    $headerData = $meta['wrapper_data'];
    if(is_array($headerData) && is_array(@$headerData['headers'])) $headerData = $headerData['headers']; // mh_edit this is added to get to the actual response headers into $headerData

    if (preg_match("/HTTP.... 30./", $headerData[0])) $redirect = true;
    else {
        $redirect = false;
    }

    $i = 0;
    foreach ($headerData as $line) {
        $i++;

        if ($i > 1 && preg_match("/^HTTP\/1../", $line)) {
            // no multiple HTTP headers will be replied
            exit;
        }

        logline("proxy, got header: ", $line);

        // make 302 redirects work
        if ($redirect && !preg_match("#$rewritebase#", $line)) {

            // a redirect to root is a redirect to main page here
            $line = preg_replace("#^Location: /$#i", "Location: $rewritebase/$abbreviation/", $line);

            // a relative redirect
            if (preg_match("#^Location: /(.+)#i", $line, $matches)) {

                if ($useHashes) {

                    // will have to be rewritten to obfuscated path if hashes are used

                    $relativePath = repress_obfuscate($matches[1], $secret);
                    rtrim($relativePath);
                    $line = "Location: $rewritebase/$abbreviation/$relativePath";

                } else {

                    $line = preg_replace("#^Location: /(.+)#i", "Location: $rewritebase/$abbreviation/$1", $line);

                }

            }

            // we localize redirects to all known hosts, and subdomains of those hosts
            foreach ($remoteservers as $knownhost) {
                if ($useHashes) {
                    $knownhostAbbr = repress_obfuscate($knownhost, $secret);
                } else {
                    $knownhostAbbr = $knownhost;
                }

                // todo: Use something similar to repress_recognize_host() mechanism here!

                // an absolute redirect to a main page
                $line = preg_replace("#^Location: http://$knownhost$#", "Location: $rewritebase/$knownhostAbbr", $line);
                $line = preg_replace("#^Location: http://$knownhost/$#", "Location: $rewritebase/$knownhostAbbr", $line);
                // an absolute redirect to a lower page, which may be an obfuscated path
                if ($useHashes) {
                    if (preg_match("#^Location: http://$knownhost/(.*)$#", $line, $matches)) {
                        $obfsPath = repress_obfuscate($matches[1], $secret);
                        $obfsPath = rtrim($obfsPath);
                        $line = preg_replace("#^Location: http://$knownhost/(.*)$#", "Location: $rewritebase/$knownhostAbbr/$obfsPath", $line);
                    }
                } else {
                    $line = preg_replace("#^Location: http://$knownhost/(.*)$#", "Location: $rewritebase/$knownhostAbbr/$1", $line);
                }

                // Support subdomains

                if ($useHashes) {

                    // an absolute redirect to a main page
                    if (preg_match("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost$#", $line, $matches)) {
                        $abbrSub = repress_obfuscate($matches[1] . '.' . $knownhost, $secret);
                        $abbrSub = rtrim($abbrSub);
                        $line = preg_replace("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost#", "Location: $rewritebase/$abbrSub", $line);
                    }
                    if (preg_match("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost/$#", $line, $matches)) {
                        $abbrSub = repress_obfuscate($matches[1] . '.' . $knownhost, $secret);
                        $abbrSub = rtrim($abbrSub);
                        $line = preg_replace("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost/#", "Location: $rewritebase/$abbrSub", $line);
                    }
                    // an absolute redirect to a lower page, an obfuscated path
                    if (preg_match("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost/(.*)$#", $line, $matches)) {
                        $abbrSub = repress_obfuscate($matches[1] . '.' . $knownhost, $secret);
                        $abbrSub = rtrim($abbrSub);
                        $obfsPath = repress_obfuscate($matches[2], $secret);
                        $obfsPath = rtrim($obfsPath);
                        $line = preg_replace("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost/(.*)$#", "Location: $rewritebase/$abbrSub/$obfsPath", $line);
                    }

                } else {
                    // an absolute redirect to a main page
                    $line = preg_replace("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost$#", "Location: $rewritebase/$1.$knownhostAbbr", $line);
                    $line = preg_replace("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost/$#", "Location: $rewritebase/$1.$knownhostAbbr", $line);
                    // an absolute redirect to a lower page, not an obfuscated path
                    $line = preg_replace("#^Location: http://([a-zA-Z0-9\.\-]*?)\.$knownhost/(.*)$#", "Location: $rewritebase/$1.$knownhostAbbr/$2", $line);
                }
            }
        }

        // cookie handling
        if (preg_match("/^Set-Cookie: /i", $line)) {

            if ($doCookies == false) {

                continue;

            }

            logline("proxy, found cookie header ", $line);

            // rewrite cookie paths

            if (preg_match("#; path=([^;]*)#", $line, $matches)) {

                $pathNow = $matches[1];

                logline("proxy, cookie path found ", $pathNow);

                if (preg_match("/^/", $pathNow)) {

                    $pathNew = "$rewritebase/$abbreviation" . $pathNow;
                    $line = preg_replace("#; path=([^;]*)#", "; path=$pathNew", $line);

                    logline("proxy, insecure path. setting to ", $pathNew);
                }

            }


            // set all cookies to be httponly

            if (!preg_match("/HttpOnly/i", $line)) {
                logline("proxy, setting this cookie to httponly");

                $line .= "; httpOnly";
            }

        }

        // get content type
        if (preg_match("/^Content-Type: text\/.*$/i", $line)) {
            $text = true;
        }

        // ignore robots header. we have our own

        if (preg_match("/^X-Robots-Tag: /i", $line)) {
            continue;
        }

        // pass through headers

        logline("proxy, give header: ", $line);
        header($line);

    }

    // After a 30x relocation response, exit immediatly
    if ($redirect) {
        logline("proxy, exit because relocate");
        exit;
    }

    // add no robots header
    header("X-Robots-Tag: noindex, nofollow", true);

    if ($text) {

        /* Read text page and close handle */
        $contents = $one_byte . stream_get_contents($handle); // mh_edit add the one byte read already to $contents
        fclose($handle);

    } else {

        /* Pass through binary content or non-parsed content */

        logline("proxy, starting passthru() of binary data from ", "http://$remoteserver/$extra");
        echo $one_byte; // mh_edit add the one byte read already to the output stream
        $size = fpassthru($handle)+1; // mh_edit add the one byte read already to the size of the data read
        logline("proxy, binary passthru() finished. closing handle");
        fclose($handle);
        logline("proxy, total binary tranfer size = ", $size);
        if ($size > 0) {
            logline("proxy, registering bandwidth usage of binary content to");
            register_bandwidth_usage($size);
        }
        exit;

    }

    // Proxy rewrite resource

    proxyhelp_init_for_repress($rewritebase, $abbreviation, $remoteservers, $useHashes, $secret);

    $contents = proxify_html_resource($contents);

    /* Push text. */

    $size = strlen($contents);
    if ($size > 0) {
        logline("proxy, registering bandwidth usage of text content");
        register_bandwidth_usage($size);
    }
    echo $contents;

    /* Done. */

    exit;

}

}

// This function takes a plain hostname and determines if RePress is authorized to proxy it, and obliged to rewrite it
// returns either TRUE or FALSE
function repress_recognize_host($stripped) {

    logline("repress_recognize_host, host = ", $stripped);

    $remoteservers = json_decode( get_option('repress_remoteservers'), TRUE );

    /** First check if this hostname is legal **/

    // split the domain into subdomains
    $subdomains = explode('.', $stripped);

    foreach ($subdomains as $subdom) {
        if (!is_legal_domain_part($subdom)) {
            logline("repress_recognize_host, illegal domain part ", $subdom);
            return FALSE;       // will not work with this object
        }
    }

    /** Now search to find if this hostname is one of the (sub)domains we proxy **/

    foreach ($remoteservers as $hostname) {

        logline("repress_recognize_host, match checking on ", $hostname);

        // split the proxied domain into subdomains

        $proxiedSubdomains = explode('.', $hostname);
        $numParts = count($proxiedSubdomains);

        if (!($numParts > count($subdomains))) {

            $okMatch = true;

            for ($i = $numParts - 1, $b = count($subdomains) - 1; $i >= 0; $i--,$b--) {
                logline("repress_recognize_host, proxied domain subpart is ", $proxiedSubdomains[$i]);
                if ($proxiedSubdomains[$i] !== $subdomains[$b]) {
                    logline("repress_recognize_host, proxied domain subpart does not match ", $subdomains[$b]);
                    $okMatch = false;
                    break;
                } else {
                    logline("repress_recognize_host, proxied domain subpart matches ", $subdomains[$b]);
                }
            }

            if ($okMatch) {
                return TRUE;
            }

        }

    }

    return FALSE;       // no match was found

}


// Build the url string with GET query if neccessary, todo force HTTPS if neccesary */
function repress_build_query_url($url) {

    logline("repress_build_query_url, url = ", $url);

        $parsed = parse_url($url);

        if (isset($parsed['query'])) {

                return $parsed['scheme'] . '://' . $parsed['host'] . $parsed['path'] . '?' . repress_rawqueryencode($parsed['query']);

        } elseif (isset($parsed['path'])) {

                return $parsed['scheme'] . '://' . $parsed['host'] . $parsed['path'];

        } else {

                return $parsed['scheme'] . '://' . $parsed['host'];

        }

}

function repress_rawqueryencode($urlPart) {

    logline("repress_rawqueryencode, urlpart = ", $urlPart);

    $queryString = '';

    $assignments = explode('&', $urlPart);

    $first = true;

    foreach ($assignments as $assignment) {

        if ($first) {
            $first = false;
        } else {
            $queryString .= '&';
        }

        // raw url encode of value

        if (!preg_match("/\=/", $assignment)) {
            logline("repress_rawqueryencode, this does not look like an assignment: ",  $assignment);
            logline("repress_rawqueryencode, adding to query string as literal");
            $queryString .= $assignment;
        } else {
            $dec = explode("=", $assignment);
            $queryString .= $dec[0] .= '=';
            if (isset($dec[1])) {
                $queryString .= rawurlencode($dec[1]);
            }
        }

    }

    return $queryString;
}

function register_bandwidth_usage($size) {

    logline("register_bandwidth_usage, size = ", $size);

    if ( function_exists('repress_register_bandwidth_usage') ) {
        repress_register_bandwidth_usage($size);
    }

}

/** Log and debug functions **/

// dump a log line to debug file
function logline($line, $data = '') {
    if (!$GLOBALS['proxydebug'] || !$GLOBALS['proxydebugfile']) { return; }

    if (!is_link($GLOBALS['proxydebugfile'])) {

        // prepare printing of data

        $printData = $data;

        if (is_nonprintable_string($data)) {
            $printData = '[nonprintable. hex dump] ' . hexdump_with_spaces( bin2hex($data) );
        }

        $printLine = $line . $printData;

        if (strlen($printLine > 2048)) {
            // truncate
            $printLine = substr($printLine, 0, 2048);
        }

        // write log line to file

        $now = date("Ymd H:i:s");
        $f = fopen($GLOBALS['proxydebugfile'], "a");

        if (flock($f, LOCK_EX)) {
            fputs($f, '[' . $now . '] ' . $printLine . "\n");
            fflush($f);
            flock($f, LOCK_UN); // release the lock
        }

        fclose($f);
    }
}

// this function determines if string is easy printable asci, like hostnames, otherwise we hex dump the data string
// utf8 not supported
function is_nonprintable_string($str) {

    for ($i = 0; $i < strlen($str); $i++) {
        $ascii = ord($str[$i]);
        if ($ascii < 32 || $ascii > 126) {
            return TRUE;
        }
    }

    return FALSE;

}

// format hex output with spaces
function hexdump_with_spaces($hexstr) {
    $r = '';
    for ($i = 0; $i < strlen($hexstr); $i++) {
        if ($i > 0 && $i % 2 == 0) {
            $r .= ' ';
        }
        $r .= $hexstr[$i];
    }
    return $r;
}