<?php

# PHP FCGI to Extend NGINX WebDAV
# Written by Jason LaPorte (jason@agoragames.com)
#
# Copyright (C) 2009 Agora Games, Inc.
#
# This software is provided 'as-is', without any express or implied warranty.
# In no event will the authors be held liable for any damages arising from the
# use of this software.
#
# Permission is granted to anyone to use this software for any purpose,
# including commercial applications, and to alter it and redistribute it
# freely, subject to the following restrictions:
#
# 1.  The origin of this software must not be misrepresented; you must not
#     claim that you wrote the original software. If you use this software
#     in a product, an acknowledgment in the product documentation would be
#     appreciated but is not required.
# 2.  Altered source versions must be plainly marked as such, and must not be
#     misrepresented as being the original software.
# 3.  This notice may not be removed or altered from any source distribution.
#
# MIME type determination, miscellaneous error handling, and general code
# structure adapted from YUNO's similar Perl CGI script[1]. More information
# about this script can be found on the Agora Games website[2].
#
# [1]: http://plan9.aichi-u.ac.jp/netlib/webappls/webdav.cgi
# [2]: http://blog.agoragames.com/2009/03/20/webdav-nginx-play-nice/
#
# Version History:
# *   3/17/2009: V1. (Initial version.)
# *   3/19/2009: V2. (Added basic support for the COPY and MOVE methods. Added
#     ZLib license for public distribution.)
# *   3/20/2009: V3. (Added recursive_copy and recursive_unlink functions,
#     eliminating the need to fork processes.)
#
# To-Do:
# *   Support (or, at least, stub out) PROPPATCH, LOCK, and UNLOCK operations.
# *   Properly support the DEPTH header in COPY requests.
# *   Properly support the various options for PROPFIND requests. (Ha!)

# Recursively delete $src. This is equivalent to UNIX's "rm -rf". Be very
# careful how you use it. Returns true on success and false on failure. (On
# failure, files that could not be deleted will obviously remain.)
function recursive_unlink ($src) {
  if (file_exists ($src)) {
    if (is_dir ($src)) {
      foreach (scandir ($src) as $child)
        if ($child != '.' && $child != '..')
          recursive_unlink ("$src/$child");

      return rmdir ($src);
    }

    else
      return unlink ($src);
  }

  return false;
}

# Recursively copy $src to $dest. If $dest already exists, it will be
# overwritten. (This makes this function not quite semantically identical to
# UNIX's "cp -r".) Returns true on success and false on failure. On failure,
# $dest may be destroyed, regardless of whether it existed before the copy or
# not. Thus, if you call this function, treat $dest as forfeit.
# FIXME: We should preserve permissions in the copy.
function recursive_copy ($src, $dest) {
  if (file_exists ($src)) {
    recursive_unlink ($dest);

    if (is_dir ($src)) {
      mkdir ($dest);

      foreach (scandir ($src) as $child)
        if ($child != '.' && $child != '..')
          if (!recursive_copy ("$src/$child", "$dest/$child")) {
            recursive_unlink ($dest);
            return false;
          }

      return true;
    }

    else if (is_link ($src))
      return symlink (readlink ($src), $dest);

    else
      return copy ($src, $dest);
  }

  return false;
}

# Validate $key, treating it as $default if not supplied, according to the
# possible values in $options.
function validate ($key, $default, $options) {
  if (is_null ($key) || $key === '') $key = $default;
  return $options[$key];
}

# Gets the MIME type of a particular file by examining its file extension. This
# could be greatly improved by doing something similar to the UNIX "file"
# command (e.g. examining headers), but this is a quick and easy hack.
function mime_type ($path) {
  # I love how PHP makes me want to kill myself. Why doesn't it support
  # nonscalar constants?
  $mime_types = array (
    'aif'   => 'audio/x-aiff',
    'aiff'  => 'audio/x-aiff',
    'asc'   => 'text/plain',
    'atom'  => 'text/plain',
    'au'    => 'audio/basic',
    'avi'   => 'video/x-msvideo',
    'bmp'   => 'image/bmp',
    'c'     => 'text/plain',
    'cc'    => 'text/plain',
    'cgi'   => 'text/plain',
    'cpp'   => 'text/plain',
    'css'   => 'text/css',
    'cxx'   => 'text/plain',
    'doc'   => 'application/msword',
    'dv'    => 'video/x-dv',
    'eps'   => 'application/postscript',
    'gif'   => 'image/gif',
    'gz'    => 'application/x-gzip',
    'h'     => 'text/plain',
    'hpp'   => 'text/plain',
    'hqx'   => 'application/mac-binhex40',
    'htm'   => 'text/html',
    'html'  => 'text/html',
    'hxx'   => 'text/plain',
    'jar'   => 'application/java-archive',
    'jav'   => 'text/plain',
    'java'  => 'text/plain',
    'jpeg'  => 'image/jpeg',
    'jpg'   => 'image/jpeg',
    'js'    => 'text/plain',
    'lzh'   => 'application/x-lzh',
    'm'     => 'text/plain',
    'm4a'   => 'audio/mp4a-latm',
    'mid'   => 'audio/midi',
    'midi'  => 'audio/midi',
    'mm'    => 'text/plain',
    'mov'   => 'video/quicktime',
    'mp2'   => 'audio/mpeg',
    'mp3'   => 'audio/mpeg',
    'mp4'   => 'video/mp4',
    'mpeg'  => 'video/mpeg',
    'mpg'   => 'video/mpeg',
    'ogg'   => 'application/ogg',
    'pdf'   => 'application/pdf',
    'php'   => 'text/plain',
    'pict'  => 'image/pict',
    'pl'    => 'text/plain',
    'png'   => 'image/png',
    'ppt'   => 'application/vnd.ms-powerpoint',
    'ps'    => 'application/postscript',
    'py'    => 'text/plain',
    'rb'    => 'text/plain',
    'rdf'   => 'text/plain',
    'rm'    => 'audio/x-pn-realaudio',
    'rtf'   => 'text/rtf',
    'sh'    => 'text/plain',
    'shtml' => 'text/html',
    'snd'   => 'audio/basic',
    'svg'   => 'image/svg+xml',
    'swf'   => 'application/x-shockwave-flash',
    'tar'   => 'application/x-tar',
    'tex'   => 'application/x-tex',
    'tif'   => 'image/tiff',
    'tiff'  => 'image/tiff',
    'txt'   => 'text/plain',
    'vrml'  => 'model/vrml',
    'wav'   => 'audio/x-wav',
    'wbmp'  => 'image/vnd.wap.wbmp',
    'wrl'   => 'model/vrml',
    'xbm'   => 'image/x-xbitmap',
    'xhtml' => 'text/html',
    'xls'   => 'application/vnd.ms-excel',
    'xml'   => 'text/xml',
    'xpm'   => 'image/x-xpixmap',
    'xsl'   => 'text/xsl',
    'zip'   => 'application/zip'
  );

  $extension = substr (strrchr ($path, '.'), 1);
  $mime = $mime_types[$extension];

  return $mime ? $mime : 'application/octet-stream';
}

# PROPFIND is recursive in nature, so it gets its own function. Since we
# assume "allprop" is set, it's not especially complicated: just stat() a file
# and format the results as XML. (Granted, the XML formatting is kinda silly,
# but you can blame the WebDAV folks for that.)
function propfind ($root, $path, $depth) {
  $href = str_replace (array ('%2F', '+'),
                       array ('/', '%20'),
                       urlencode ($path));
  $file = $root . $path;
  $exists = file_exists ($file);
  $dir = NULL;
  $stat = NULL;

  if ($href === '')
    $href = '/';

  if ($exists) {
    $dir = is_dir ($file);
    $stat = stat ($file);
  }

  echo ('<response>');
  echo ("<href>$href</href>");
  echo ('<propstat>');

  # File not found.
  if (!$exists)
    echo ('<status>HTTP/1.1 404 File Not Found</status>');

  # If we can't stat the file, it's probably a permissions issue. (I use a
  # 403 and not a 401 because the client can never recover from the error--
  # it's based on the server's permissions, not the client's.)
  else if (!$stat)
    echo ('<status>HTTP/1.1 403 Forbidden</status>');

  else {
    echo ('<status>HTTP/1.1 200 OK</status>');
    echo ('<prop>');

    $name = htmlspecialchars (basename ($file));
    $created = gmdate ('c', $stat['ctime']);
    $modified = gmdate ('c', $stat['mtime']);

    # Display various general properties.
    echo ("<displayname>$name</displayname>");
    echo ("<creationdate>$created</creationdate>");
    echo ("<getlastmodified>$modified</getlastmodified>");
    echo ('<supportedlock/>');

    # If it's a directory, say so.
    if ($dir)
      echo ('<resourcetype><collection/></resourcetype>');

    # Otherwise, print out statistics that only make sense on files.
    else {
      $size = $stat['size'];
      $mime = mime_type ($path);
      $etag = "{$stat['dev']}-{$stat['ino']}-{$stat['mtime']}";

      echo ('<resourcetype/>');
      echo ("<getcontentlength>$size</getcontentlength>");
      echo ("<getcontenttype>$mime</getcontenttype>");
      echo ("<getetag>$etag</getetag>");
    }

    echo ('</prop>');
  }

  echo ('</propstat>');
  echo ('</response>');

  # If this is a directory and we're set to recurse, then also print out
  # PROPFIND responses for all of this directory's children.
  if ($dir && $depth > 0)
    foreach (scandir ($file) as $child)
      if ($child != '.' && $child != '..')
        propfind ($root, "$path/$child", $depth - 1);
}

# Response handling begins here. (Determine what method is being called, and
# respond appropriately.)

$request_method = $_SERVER['REQUEST_METHOD'];

switch ($request_method) {
  # PROPFIND supports a truly staggering amount of options and flags to limit
  # or define the various pieces of data you're interested in retrieving. We
  # pretend that the client has always specified "allprop" (that is, complete
  # information about everything), and make it the client's responsibility to
  # pull out less information if so desired.
  case 'PROPFIND':
    # Figure out what file they're looking at.
    $document_root = $_SERVER['DOCUMENT_ROOT'];
    $document_uri = urldecode (rtrim ($_SERVER['DOCUMENT_URI'], '/'));

    # Figure out what depth to recurse to. Valid values are 0, 1, and infinity.
    $depth = validate ($_SERVER['DEPTH'],
                       'infinity',
                       array ('0' => 0, '1' => 1, 'infinity' => 'infinity'));

    # Choke if they specify an invalid depth.
    if (is_null ($depth))
      header ('HTTP/1.1 400 Bad Request');

    # "allprop" with an infinite depth is a scary proposition. Supporting it is
    # both optional and stupid, so I don't.
    else if ($depth === 'infinity') {
      header ('HTTP/1.1 403 Forbidden');
      header ('Content-Type: text/xml');

      echo ('<error xmlns="DAV:">');
      echo ('<propfind-finite-depth/>');
      echo ('</error>');
    }

    # Otherwise, give them the requested information.
    else {
      header ('HTTP/1.1 207 Multi-Status');
      header ('Content-Type: text/xml');

      echo ('<multistatus xmlns="DAV:">');
      propfind ($document_root, $document_uri, $depth);
      echo ('</multistatus>');
    }

    break;

  # We handle COPY and MOVE together, since they're almost identical. COPY
  # should support the Depth header, which modifies the semantics of the copy.
  # We ignore it and assume an infinite depth. Additionally, we do not support
  # copies between servers--all copies must be local. Finally, we don't
  # properly check for disk space errors, but a generic 500 should be good
  # enough.
  case 'COPY':
  case 'MOVE':
    # Figure out what files they're looking at.
    $host = $_SERVER['HOST'];
    $document_root = $_SERVER['DOCUMENT_ROOT'];
    $document_uri = urldecode (rtrim ($_SERVER['DOCUMENT_URI'], '/'));

    $destination = NULL;
    $destination_host = NULL;
    $url = parse_url ($_SERVER['DESTINATION']);

    if ($url) {
      $destination = urldecode (rtrim ($url['path'], '/'));
      $destination_host = $url['host'];
    }

    $source_exists = file_exists ($document_root . $document_uri);
    $destination_exists = file_exists ($document_root . $destination);

    # Do we overwrite the destination file?
    $overwrite = validate ($ENV_['OVERWRITE'],
                           'T',
                           array ('T' => true, 't' => true,
                                  'F' => false, 'f' => false));

    # Choke if they specify an invalid destination or depth.
    if (is_null ($destination))
      header ('HTTP/1.1 400 Bad Request');

    # Disallow copying/moving to a remote host.
    else if ($host != $destination_host)
      header ('HTTP/1.1 502 Bad Gateway');

    # Fail if the source doesn't exist.
    else if (!$source_exists)
      header ('HTTP/1.1 404 File Not Found');

    # Disallow copying/moving a file to itself.
    else if ($document_uri == $destination)
      header ('HTTP/1.1 403 Forbidden');

    # Fail if the destination file exists and they said they didn't want to
    # overwrite it.
    else if ($overwrite == false && $destination_exists)
      header ('HTTP/1.1 412 Precondition Failed');

    # If we're doing a copy, copy the files.
    # FIXME: We resort to shell since PHP doesn't support a recursive copy and
    # I didn't want to bother implementing it (though it would be a good idea
    # to do so at some point).
    else if ($request_method == 'COPY' &&
             !recursive_copy ($document_root . $document_uri,
                              $document_root . $destination))
      header ('500 Internal Server Error');

    # If we're doing a move, move the files.
    else if ($request_method == 'MOVE' &&
             !rename ($document_root . $document_uri,
                      $document_root . $destination))
      header ('500 Internal Server Error');

    else
      header ($destination_exists ?
                'HTTP/1.1 204 No Content' :
                'HTTP/1.1 201 Created');

    break;

  # In case they ask, pretend that we actually know what we're talking about.
  # (The only methods conspicuously absent are PROPPATCH, LOCK, and UNLOCK. We
  # tell the clients that we don't support them.)
  case 'OPTIONS':
    header ('HTTP/1.1 200 OK');
    header ('Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, MKCOL, COPY, MOVE, PROPFIND');
    header ('DAV: 1, 2');
    break;

  # The following methods are valid but unimplemented. In theory, NGINX is
  # supposed to handle each of them anyway.
  case 'GET':
  case 'HEAD':
  case 'POST':
  case 'PUT':
  case 'DELETE':
  case 'MKCOL':
    header ('HTTP/1.1 501 Not Implemented');
    break;

  # Any other methods are unknown.
  default:
    header ('HTTP/1.1 400 Bad Request');
    break;
}

?>