td

README

td

A fast Telegram client in pure Go.

• Examples
• Security policy
• User support and dev chat
• Roadmap
• Contributing
• Architecture

Before using this library, read How To Not Get Banned guide.

Usage

go get github.com/gotd/td

package main

import (
	"context"

	"github.com/gotd/td/telegram"
)

func main() {
	// https://core.telegram.org/api/obtaining_api_id
	client := telegram.NewClient(appID, appHash, telegram.Options{})
	if err := client.Run(context.Background(), func(ctx context.Context) error {
		// It is only valid to use client while this function is not returned
		// and ctx is not cancelled.
		api := client.API()

		// Now you can invoke MTProto RPC requests by calling the API.
		// ...

		// Return to close client connection and free up resources.
		return nil
	}); err != nil {
		panic(err)
	}
	// Client is closed.
}

See examples for more info.

Status

Work is still in progress (mostly helpers and convenience wrappers), but basic functionality were tested in production and works fine. Only go1.16 is supported and no backward compatibility is provided for now.

The goal of this project is to implement a stable, performant and safe client for Telegram in pure Go while having a simple and convenient API and a feature parity with TDLib.

This project is fully non-commercial and not affiliated with any commercial organization (including Telegram LLC).

Also, see the comparison with other Go Telegram clients.

Features

• Low memory overhead, 150kb per idle client
• Full MTProto 2.0 implementation in Golang
• Code for Telegram types generated by ./cmd/gotdgen (based on gotd/tl parser) with embedded official documentation
• Pluggable session storage
• Automatic re-connects with keepalive
• Vendored Telegram public keys that are kept up-to-date
• Rigorously tested
  • End-to-end with real Telegram server in CI
  • End-to-end with gotd Telegram server (in pure Go)
  • Lots of unit testing
  • Fuzzing
  • 24/7 canary bot in production that tests reconnects, update handling, memory leaks and performance
• No runtime reflection overhead
• Conforms to Security guidelines for Telegram client software developers
  • Secure PRNG used for crypto
  • Replay attack protection
• 2FA support
• MTProxy support
• Various helpers that lighten the complexity of the Telegram API
  • uploads for big and small files with multiple streams for single file and progress reporting
  • downloads with CDN support, also multiple streams
  • messages with various convenience builders and text styling support
  • query with pagination helpers
  • middleware for rate limiting and FLOOD_WAIT handling
• CDN support with connection pooling
• Automatic datacenter migration and redirects handling
• Graceful request cancellation via context
• WebSocket transport support (works in WASM)

Examples

See examples directory.

Also take a look at

• gotd/bot with updates recovery enabled, used as canary for stability testing
• gotd/cli, command line interface for subset of telegram methods.

Auth

User

You can use td/telegram/auth.Flow to simplify user authentications.

codePrompt := func(ctx context.Context, sentCode *tg.AuthSentCode) (string, error) {
    // NB: Use "golang.org/x/crypto/ssh/terminal" to prompt password.
    fmt.Print("Enter code: ")
    code, err := bufio.NewReader(os.Stdin).ReadString('\n')
    if err != nil {
        return "", err
    }
    return strings.TrimSpace(code), nil
}
// This will setup and perform authentication flow.
// If account does not require 2FA password, use telegram.CodeOnlyAuth
// instead of telegram.ConstantAuth.
if err := auth.NewFlow(
    auth.Constant(phone, password, auth.CodeAuthenticatorFunc(codePrompt)),
    auth.SendCodeOptions{},
).Run(ctx, client.Auth()); err != nil {
    panic(err)
}

Bot

Use bot token from @BotFather.

if err := client.Auth().Bot(ctx, "token:12345"); err != nil {
    panic(err)
}

Calling MTProto directly

You can use the generated tg.Client that allows calling any MTProto method directly.

// Grab these from https://my.telegram.org/apps.
// Never share it or hardcode!
client := telegram.NewClient(appID, appHash, telegram.Options{})
client.Run(ctx, func(ctx context.Context) error) {
  // Grab token from @BotFather.
  if err := client.Auth().Bot(ctx, "token:12345"); err != nil {
    return err
  }
  state, err := client.API().UpdatesGetState(ctx)
  if err != nil {
    return err
  }
  // Got state: &{Pts:197 Qts:0 Date:1606855030 Seq:1 UnreadCount:106}
  // This will close client and cleanup resources.
  return nil
}

Generated code

The code output of gotdgen contains references to TL types, examples, URL to official documentation and extracted comments from it.

For example, the auth.Authorization type in tg/tl_auth_authorization_gen.go:

// AuthAuthorizationClass represents auth.Authorization generic type.
//
// See https://core.telegram.org/type/auth.Authorization for reference.
//
// Example:
//  g, err := DecodeAuthAuthorization(buf)
//  if err != nil {
//      panic(err)
//  }
//  switch v := g.(type) {
//  case *AuthAuthorization: // auth.authorization#cd050916
//  case *AuthAuthorizationSignUpRequired: // auth.authorizationSignUpRequired#44747e9a
//  default: panic(v)
//  }
type AuthAuthorizationClass interface {
	bin.Encoder
	bin.Decoder
	construct() AuthAuthorizationClass
}

Also, the corresponding auth.signIn method:

// AuthSignIn invokes method auth.signIn#bcd51581 returning error if any.
// Signs in a user with a validated phone number.
//
// See https://core.telegram.org/method/auth.signIn for reference.
func (c *Client) AuthSignIn(ctx context.Context, request *AuthSignInRequest) (AuthAuthorizationClass, error) {}

The generated constructors contain detailed official documentation, including links:

// FoldersDeleteFolderRequest represents TL type `folders.deleteFolder#1c295881`.
// Delete a peer folder¹
//
// Links:
//  1) https://core.telegram.org/api/folders#peer-folders
//
// See https://core.telegram.org/method/folders.deleteFolder for reference.
type FoldersDeleteFolderRequest struct {
    // Peer folder ID, for more info click here¹
    //
    // Links:
    //  1) https://core.telegram.org/api/folders#peer-folders
    FolderID int
}

Contributions

Huge thanks to all contributors. Dealing with a project of this scale alone is impossible.

Special thanks:

• tdakkota
  • Two-factor authentication (SRP)
  • Proxy support
  • Update dispatcher
  • Complete transport support (abridged, padded intermediate and full)
  • Telegram server for end-to-end testing
  • Multiple major refactorings, including critical cryptographical scope reduction
  • Code generation improvements (vector support, multiple modes for pretty-print)
  • And many other cool things and performance improvements
• xjem
  • Background pings
  • Links in generated documentation
  • Message acknowledgements
  • Retries
  • RPC Engine
  • Gap (Updates) engine

Reference

The MTProto protocol description is hosted by Telegram.

Most important parts for client implementations:

• Security guidelines for client software developers

Current implementation mostly conforms to security guidelines, but no formal security audit were performed.

Prior art

• Lonami/grammers (Great Telegram client in Rust, many test vectors were used as reference)
• sdidyk/mtproto, cjongseok/mtproto, xelaj/mtproto (MTProto 1.0 in go)

Difference to other projects

Status by 11.07.2021

Topic	gotd		xelaj/mtproto
🚧 Maintainers	At least 3 core contributors, 1.7K commits, actively maintained, automatically updated to latest layer		Single core contributor, 150 commits, effectively not maintaned from March 2021, failed to update to 129 layer
🔒️ Security	MTProto v2, conforms to security guidelines		MTProto v1 that is insecure and deprecated since 2017 (SHA-1 is used instead of SHA-256), code was probably copied from sdidyk/mtproto or cjongseok/mtproto with little understanding
🚀 Features	MTProxy support, WebSocket transport, helpers for uploads, downloads, messages, text styling, datacenter redirects handling and more, but you can still use the raw API		Raw MTProto API
🔨 Platforms	All platforms including WASM and special stability features for Windows that considers clock resolution		Limited support for Windows
⚡️ Performance	Multiple optimizations for zero allocations		Uses reflection in runtime
🧪 Stability	Lots of unit tests (237 tests, 943 including subtests), end-to-end tests with self-made Telegram server in Go, end-to-end tests with real test servers, fuzzing		12 unit tests, 41 including sub-tests
⭐ GitHub Stargazers	Has only 192 stars		Has 643 stars, which is much higher

License

MIT License

Created by Aleksandr (ernado) Razumov

2020

Documentation

Overview

Package td implements MTProto encoding and decoding.