Marc A. Lehmann > AnyEvent-FCP > AnyEvent::FCP



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AnyEvent::FCP - freenet client protocol 2.0


   use AnyEvent::FCP;

   my $fcp = new AnyEvent::FCP;

   # transactions return condvars
   my $lp_cv = $fcp->list_peers;
   my $pr_cv = $fcp->list_persistent_requests;

   my $peers = $lp_cv->recv;
   my $reqs  = $pr_cv->recv;


This module implements the freenet client protocol version 2.0, as used by freenet 0.7. See Net::FCP for the earlier freenet 0.5 version.

See for a description of what the messages do.

The module uses AnyEvent to find a suitable event module.

Only very little is implemented, ask if you need more, and look at the example program later in this section.


This example fetches the download list and sets the priority of all files with "a" in their name to "emergency":

   use AnyEvent::FCP;

   my $fcp = new AnyEvent::FCP;

   $fcp->watch_global (1, 0);
   my $req = $fcp->list_persistent_requests;

TODO for my $req (values %$req) { if ($req->{filename} =~ /a/) { $fcp->modify_persistent_request (1, $req->{identifier}, undef, 0); } }


Nothing much can be "imported" from this module right now.


$fcp = new AnyEvent::FCP key => value...;

Create a new FCP connection to the given host and port (default, or the environment variables FREDHOST and FREDPORT).

If no name was specified, then AnyEvent::FCP will generate a (hopefully) unique client name for you.

The following keys can be specified (they are all optional):

name => $string

A unique name to identify this client. If none is specified, a randomly generated name will be used.

host => $hostname

The hostname or IP address of the freenet node. Default is $ENV{FREDHOST} or

port => $portnumber

The port number of the FCP port. Default is $ENV{FREDPORT} or 9481.

timeout => $seconds

The timeout, in seconds, after which a connection error is assumed when there is no activity. Default is 7200, i.e. two hours.

keepalive => $seconds

The interval, in seconds, at which keepalive messages will be sent. Default is 540, i.e. nine minutes.

These keepalive messages are useful both to detect that a connection is no longer working and to keep any (home) routers from expiring their masquerading entry.

on_eof => $callback->($fcp)

Invoked when the underlying AnyEvent::Handle signals EOF, currently regardless of whether the EOF was expected or not.

on_error => $callback->($fcp, $message)

Invoked on any (fatal) errors, such as unexpected connection close. The callback receives the FCP object and a textual error message.

on_failure => $callback->($fcp, $type, $backtrace, $args, $error)

Invoked when an FCP request fails that didn't have a failure callback. See "FCP REQUESTS" for details.


The following methods implement various requests. Most of them map directory to the FCP message of the same name. The added benefit of these over sending requests yourself is that they handle the necessary serialisation, protocol quirks, and replies.

All of them exist in two versions, the variant shown in this manpage, and a variant with an extra _ at the end, and an extra $cb argument. The version as shown is synchronous - it will wait for any replies, and either return the reply, or croak with an error. The underscore variant returns immediately and invokes one or more callbacks or condvars later.

For example, the call

   $info = $fcp->get_plugin_info ($name, $detailed);

Also comes in this underscore variant:

   $fcp->get_plugin_info_ ($name, $detailed, $cb);

You can thinbk of the underscore as a kind of continuation indicator - the normal function waits and returns with the data, the _ indicates that you pass the continuation yourself, and the continuation will be invoked with the results.

This callback/continuation argument ($cb) can come in three forms itself:

A code reference (or rather anything not matching some other alternative)

This code reference will be invoked with the result on success. On an error, it will invoke the on_failure callback of the FCP object, or, if none was defined, will die (in the event loop) with a backtrace of the call site.

This is a popular choice, but it makes handling errors hard - make sure you never generate protocol errors!

If an on_failure hook exists, it will be invoked with the FCP object, the request type (the name of the method), a (textual) backtrace as generated by Carp::longmess, and arrayref containing the arguments from the original request invocation and the error object from the server, in this order, e.g.:

   on_failure => sub {
      my ($fcp, $request_type, $backtrace, $orig_args, $error_object) = @_;

      warn "FCP failure ($type), $error_object->{code_description} ($error_object->{extra_description})$backtrace";
      exit 1;
A condvar (as returned by e.g. AnyEvent->condvar)

When a condvar is passed, it is sent ($cv->send ($results)) the results when the request has finished. Should an error occur, the error will instead result in $cv->croak ($error).

This is also a popular choice.

An array with two callbacks [$success, $failure]

The $success callback will be invoked with the results, while the $failure callback will be invoked on any errors.

The $failure callback will be invoked with the error object from the server.


This is the same thing as specifying sub { } as callback, i.e. on success, the results are ignored, while on failure, the on_failure hook is invoked or the module dies with a backtrace.

This is good for quick scripts, or when you really aren't interested in the results.

$peers = $fcp->list_peers ([$with_metdata[, $with_volatile]])
$notes = $fcp->list_peer_notes ($node_identifier)
$fcp->watch_global ($enabled[, $verbosity_mask])
$reqs = $fcp->list_persistent_requests
$sync = $fcp->modify_persistent_request ($global, $identifier[, $client_token[, $priority_class]])

Update either the client_token or priority_class of a request identified by $global and $identifier, depending on which of $client_token and $priority_class are not undef.

$info = $fcp->get_plugin_info ($name, $detailed)
$status = $fcp->client_get ($uri, $identifier, %kv)

%kv can contain (

ignore_ds, ds_only, verbosity, max_size, max_temp_size, max_retries, priority_class, persistence, client_token, global, return_type, binary_blob, allowed_mime_types, filename, temp_filename

$status = $fcp->remove_request ($identifier[, $global])

Remove the request with the given isdentifier. Returns true if successful, false on error.

($can_read, $can_write) = $fcp->test_dda ($local_directory, $remote_directory, $want_read, $want_write))

The DDA test in FCP is probably the single most broken protocol - only one directory test can be outstanding at any time, and some guessing and heuristics are involved in mangling the paths.

This function combines TestDDARequest and TestDDAResponse in one request, handling file reading and writing as well, and tries very hard to do the right thing.

Both $local_directory and $remote_directory must specify the same directory - $local_directory is the directory path on the client (where AnyEvent::FCP runs) and $remote_directory is the directory path on the server (where the freenet node runs). When both are running on the same node, the paths are generally identical.

$want_read and $want_write should be set to a true value when you want to read (get) files or write (put) files, respectively.

On error, an exception is thrown. Otherwise, $can_read and $can_write indicate whether you can reaqd or write to freenet via the directory.


The AnyEvent::FCP class keeps a request cache, where it caches all information from requests.

For these messages, it will store a copy of the key-value pairs, together with a type slot, in $fcp->{req}{$identifier}:


This message updates the stored data:


This message will remove this entry:


These messages get merged into the cache entry, under their type, i.e. a simple_progress message will be stored in $fcp->{req}{$identifier}{simple_progress}:

   simple_progress        # get/put

   uri_generated          # put
   generated_metadata     # put
   started_compression    # put
   finished_compression   # put
   put_failed             # put
   put_fetchable          # put
   put_successful         # put

   sending_to_network     # get
   compatibility_mode     # get
   expected_hashes        # get
   expected_mime          # get
   expected_data_length   # get
   get_failed             # get
   data_found             # get
   enter_finite_cooldown  # get

In addition, an event (basically a fake message) of type request_changed is generated on every change, which will be called as $cb->($fcp, $kv, $type), where $type is the type of the original message triggering the change,

To fill this cache with the global queue and keep it updated, call watch_global to subscribe to updates, followed by list_persistent_requests_sync.

   $fcp->watch_global_sync_; # do not wait
   $fcp->list_persistent_requests; # wait

To get a better idea of what is stored in the cache, here is an example of what might be stored in $fcp->{req}{"Frost-gpl.txt"}:

      identifier     => "Frost-gpl.txt",
      uri            => 'CHK@Fnx5kzdrfE,EImdzaVyEWl,AAIC--8/gpl.txt',
      binary_blob    => "false",
      global         => "true",
      max_retries    => -1,
      max_size       => 9223372036854775807,
      persistence    => "forever",
      priority_class => 3,
      real_time      => "false",
      return_type    => "direct",
      started        => "true",
      type           => "persistent_get",
      verbosity      => 2147483647,
      sending_to_network => {
         identifier => "Frost-gpl.txt",
         global     => "true",
      compatibility_mode => {
         identifier    => "Frost-gpl.txt",
         definitive    => "true",
         dont_compress => "false",
         global        => "true",
         max           => "COMPAT_1255",
         min           => "COMPAT_1255",
      expected_hashes    => {
         identifier => "Frost-gpl.txt",
         global     => "true",
         hashes     => {
            ed2k   => "d83596f5ee3b7...",
            md5    => "e0894e4a2a6...",
            sha1   => "...",
            sha256 => "...",
            sha512 => "...",
            tth    => "...",
      expected_mime      => {
         identifier      => "Frost-gpl.txt",
         global          => "true",
         metadata        => { content_type => "application/rar" },
      expected_data_length => {
         identifier      => "Frost-gpl.txt",
         data_length     => 37576,
         global          => "true",
      simple_progress    => {
         identifier      => "Frost-gpl.txt",
         failed          => 0,
         fatally_failed  => 0,
         finalized_total => "true",
         global          => "true",
         last_progress   => 1438639282628,
         required        => 372,
         succeeded       => 102,
         total           => 747,
      data_found           => {
         identifier      => "Frost-gpl.txt",
         completion_time => 1438663354026,
         data_length     => 37576,
         global          => "true",
         metadata        => { content_type => "image/jpeg" },
         startup_time    => 1438657196167,


   use AnyEvent::FCP;

   my $fcp = new AnyEvent::FCP;

   # let us look at the global request list
   $fcp->watch_global_ (1);

   # list them, synchronously
   my $req = $fcp->list_persistent_requests;

   # go through all requests
   for my $req (values %$req) {
      # skip jobs not directly-to-disk
      next unless $req->{return_type} eq "disk";
      # skip jobs not issued by FProxy
      next unless $req->{identifier} =~ /^FProxy:/;

      if ($req->{data_found}) {
         # file has been successfully downloaded
         ... move the file away
         (left as exercise)

         # remove the request

         $fcp->remove_request (1, $req->{identifier});
      } elsif ($req->{get_failed}) {
         # request has failed
         if ($req->{get_failed}{code} == 11) {
            # too many path components, should restart
         } else {
            # other failure
      } else {
         # modify priorities randomly, to improve download rates
         $fcp->modify_persistent_request (1, $req->{identifier}, undef, int 6 - 5 * (rand) ** 1.7)
            if 0.1 > rand;

   # see if the dummy plugin is loaded, to ensure all previous requests have finished.
   $fcp->get_plugin_info_sync ("dummy");




 Marc Lehmann <>
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