Lighttpd

Response handling in response.c¶

-- this may help to understand how the config works too.

(I removed the `con->` prefix from the code so it is easier to read; so mode is `con->mode` in the source)

The conditional checks are activated at specific points as you will see; so modules which do something in their uri_clean handler will probably never trigger if you wrap them in a `$PHYSICAL["existing-path"]` conditional.

In every `handle(something)` call the module handlers are called in the order the modules have been loaded. But this does not mean that by inserting a module before another will make it always handling the request before the other, as not every module implements every handler.

One example for this is mod_rewrite/mod_redirect: rewrite handles uri_raw, redirect uri_clean - so rewrite will always act before redirect (for now - I suggest you load mod_rewrite before mod_redirect so you are on the safe side if this changes).

The request handling is restarted if a handler returns HANDLER_COMEBACK (mod_rewrite, mod_proxy_core, mod_magnet).

TODO: At which point should `config_cond_cache_reset(srv, con);` be executed?

TODO: What about HANDLER_WAIT_FOR_FD?

If a request handler does not return HANDLER_GO_ON, request handling stops (remaining module handlers are not called!) and the return value from the handler is returned.

mode indicates which module wants to generate the content; `mode == DIRECT` ends in mod_staticfile (the default value); modules should set it to their own id if they handle the request: `con->mode = p->id`.

If `mode != DIRECT` you have to generate error messages yourself, so if you want lighty to send an error (or trigger the error-handler) mode must be DIRECT; just set http_status to an error status and return HANDLER_FINISHED.

If you want to know if another module already handled the request, do something like this:

if (con->mode != DIRECT || con->http_status != 0) return HANDLER_GO_ON;

So, let's start (this is basically the simplified code from response.c):

handle_request() {
  if (mode == DIRECT and (http_status != 0 or http_status != 200)) return HANDLER_FINISHED

  if (mode == DIRECT and empty(physical.path)) {
    // We need a physical path, i.e. a filename

    activate_conditionals($SERVER["socket"], $HTTP["scheme"], $HTTP["host"], $HTTP["remote-ip"],
        $HTTP["referer"], $HTTP["user-agent"], $HTTP["cookie"], $HTTP["request-method"])
    split(request.uri -> uri.path_raw '?' uri.query)

    handle(uri_raw)

    urldecode_and_simplify(uri.raw -> uri.path);  // "sanitising" 
    activate_conditionals($HTTP["url"], $HTTP["query-string"])

    handle(uri_clean)

    response to the query 'OPTIONS *'

    set default physical.doc_root (server.document-root from the last matching conditional)
    set default physical.rel_path = uri.path
    [lighty-1.5] filename_unix2local(phyiscal.rel_path)

    handle(docroot)

    lowercase physical.rel_path on case insensitive platforms
    physical.path = physical.docroot + physical.rel_path

    [lighty-1.5] remove trailing DIR_SEPERATOR from physical.path

    handle(phyiscal)

    activate_conditionals($PHYSICAL["path"])
  }

  if (mode == DIRECT) {
    // Now we should have a physical.path

    if (exists(phyiscal.path)) {
      if (is_symlink(phyiscal.path) and not conf.follow_symlinks) return FORBIDDEN() // 403
      if (is_dir(phyiscal.path) and uri.path does not end with a '/') return redirect_to_dir(); // append '/'
    } else if (some physical.path component was not a directory) { // errno = ENOTDIR
      split phyiscal.path into (a existing filename) physical.path and request.path_info
    }

    [lighty-1.5] activate_conditionals($PHYSICAL["existing-path"])

    [lighty-1.4] handle(subrequest_start)
    [lighty-1.5] handle(start_backend)

    [lighty-1.4] if (mode == DIRECT and http_status == 0) {
      // no one wanted to send content
      if (request.http_method == 'OPTIONS') OK() // 200
      else FORBIDDEN() // 403;
    }
  }

  [lighty-1.4] handle(subrequest);

  [lighty-1.5] if (mode == DIRECT) {
    // no one wanted to send content
    FORBIDDEN() // 403
  }
}