rtapi

rtapi is a small Go client for rTorrent's XML-RPC interface over SCGI. It is the library used by rtelegram.

Requirements

• Go 1.26 or newer.
• rTorrent built with XML-RPC support.
• A local SCGI endpoint such as a protected Unix socket or scgi_port = 127.0.0.1:5000.

The rTorrent RPC endpoint has no authentication and exposes powerful methods. Prefer a permission-protected Unix socket. Never expose SCGI directly to an untrusted network; see rTorrent's official XML-RPC security guidance.

Install

go get github.com/pyed/rtapi@latest

Example

package main

import (
	"fmt"
	"log"

	"github.com/pyed/rtapi"
)

func main() {
	rt, err := rtapi.NewRtorrent("/run/user/1000/rtorrent.sock")
	if err != nil {
		log.Fatal(err)
	}

	torrents, err := rt.Torrents()
	if err != nil {
		log.Fatal(err)
	}
	for _, torrent := range torrents {
		fmt.Printf("%s: %d/%d bytes\n", torrent.Name, torrent.Completed, torrent.Size)
	}
}

TCP addresses such as 127.0.0.1:5000 are also accepted, as are http:// and https:// XML-RPC URLs for rTorrent behind a web server, such as https://user:password@seedbox.example/RPC2. Credentials in the URL are sent with HTTP basic authentication and kept out of error messages; requests use Rtorrent.HTTPClient when it is set, as for a proxy or a certificate authority of one's own, and http.DefaultClient, which honors HTTPS_PROXY, otherwise. Basic authentication over plain http:// sends the password readably; use https:// beyond the local machine.

NewRtorrent asks rTorrent for its version, so it fails while rTorrent is down. NewClient asks nothing, for programs that may start before rTorrent; GetVersion asks for the version later. An address that is neither a URL nor host:port is a socket path, whether or not the socket exists yet.

Every method has a ...Context variant, such as TorrentsContext, and NewRtorrentContext. Cancelling the context interrupts the request. Cancellations and timeouts match context.Canceled and context.DeadlineExceeded with errors.Is. Every SCGI request is bounded by rtapi.DefaultTimeout (30 seconds) unless Rtorrent.Timeout is set. Responses default to a 16 MiB safety bound; set Rtorrent.MaxResponseSize when a legitimately large library needs more. Transport errors, malformed responses, and XML-RPC faults are returned to the caller; errors.As can inspect an *rtapi.XMLRPCFault.

API notes

• Transfer fields (Size, Completed, and UpTotal) contain exact byte counts.
• Path (d.base_path) is empty until rTorrent opens a torrent. Directory and MultiFile are always reported: Directory is the data directory of a multi-file torrent, or the directory containing a single-file torrent's file.
• SpeedsWithError returns the current transfer rates.
• DownloadRaw loads torrent bytes directly, avoiding credential-bearing intermediary URLs. DownloadWithOptions remains available for URL loading. Set DotTorrentWithOptions.Stopped to load a torrent without starting it. An empty Dir or Label leaves rTorrent's default. rTorrent parses them as command arguments and runs one that starts with $ as a command, so loads refuse such values, and those with control characters or invalid UTF-8, with ErrCommandArgument. URL loads use rTorrent's verbose load commands, so rTorrent logs why a link failed to load.
• Torrents makes two requests: one for every torrent's details and one, with a call per torrent, for their trackers. For large libraries, List with ListOptions{} skips the trackers, and Trackers fills them in later for the torrents that need them. Hashes lists only info-hashes, the cheapest way to see which torrents are loaded, and Transfers lists how much of each torrent's data has been uploaded and downloaded. Those counts leave out the protocol messages exchanged with peers, which rTorrent's global totals (Stats) include; a seeding library alone receives hundreds of megabytes of those a day.
• GetTorrent requests only the one torrent rather than listing them all.
• Errors of calls on a torrent rTorrent does not have, such as one removed since it was listed, match ErrNotFound with errors.Is; timeouts and other faults do not.
• Torrent.Finished is when a torrent completed and Torrent.Started when it first started, in Unix seconds, or 0 until then; rTorrent keeps both across restarts. Torrent.Age is when rTorrent loaded the torrent, which it does again for every torrent each time it starts, so Started is the better guide to when a torrent was added. Torrent.Added is Started, or Age for a torrent that never started, and ByAdded sorts by it; ByAge orders torrents by the time they were loaded.
• Torrent.TrackerCount is how many trackers a torrent lists. Message is what the last tracker to answer said, which need not be the first.
• Torrent.Label is d.custom1, where ruTorrent keeps its label, and SetLabel sets it. ruTorrent stores labels percent-encoded, as JavaScript's encodeURIComponent writes them, and decodes them to show them; rtapi passes labels through as they are.
• Files lists a torrent's files, and SetFilePriorities skips or prioritizes them by index (FileSkip, FileNormal, FileHigh).
• GlobalLimits and SetGlobalLimits read and set the global download and upload rate limits, in bytes per second; zero means unlimited.
• FreeDiskSpace reports the free space on the filesystem holding a torrent, and FreeDiskSpaces that of several torrents in one request. rTorrent knows where that is only for torrents it has opened, such as active ones, and reports 0 for the rest.
• Connections counts peer connections in one request: those peers opened to rTorrent, which they can only do when its port is reachable, and those rTorrent opened.
• Torrents.Sort takes an explicit rtapi.Sorting value. Sorting is stable and compares names case-insensitively.
• DeleteMetadata erases torrents from rTorrent and checks that rTorrent acknowledged every one. rtapi never deletes data: the data belongs to the rTorrent host, so an application that offers it must enforce its own containment policy there.

Versions

From v1.0.0, rtapi follows semantic versioning: v1 releases add to the API but do not break it.

v1.1.0 adds List, Trackers, and Hashes, and decodes responses several times faster with a fraction of the memory, which matters for libraries of thousands of torrents. If rTorrent drops d.multicall2, as it plans to, listing switches to d.multicall.

v1.2.0 adds Torrent.Started, and v1.3.0 adds Transfers, Stats.PID (rTorrent's process ID, which tells when rTorrent has restarted), Torrent.Private, SetLabel, FreeDiskSpaces, and Connections.

v1.4.0 refuses a load's Dir or Label that rTorrent would run as a command (ErrCommandArgument), and adds ErrNotFound, NewClient and GetVersion, Rtorrent.HTTPClient, Torrent.Added with ByAdded sorting, and Torrent.TrackerCount. Socket paths count as sockets before the socket exists.

Upgrading from v0:

• Speeds is gone; use SpeedsWithError or SpeedsContext, which report failures instead of returning zero.
• Delete and ErrUnsafeDataDelete are gone; use DeleteMetadata.
• The process-global CurrentSorting variable is gone; pass an rtapi.Sorting to Torrents.Sort.

Development

go test ./...
go vet ./...
go build ./...