irc.go

// Copyright (c) 2024 Jerzy Dąbrowski
// Based on original work by Thomas Jager, 2009. All rights reserved.
//
// This project is a fork of the original go-ircevent library created by Thomas Jager.
// Redistribution and use in source and binary forms, with or without modification, are permitted provided
// that the following conditions are met:
//
//    - Redistributions of source code must retain the above copyright notice, this list of conditions,
//      and the following disclaimer.
//    - Redistributions in binary form must reproduce the above copyright notice, this list of conditions,
//      and the following disclaimer in the documentation and/or other materials provided with the distribution.
//    - Neither the name of the original authors nor the names of its contributors may be used to endorse
//      or promote products derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT, OR OTHERWISE, ARISING FROM, OUT OF, OR IN CONNECTION WITH THE SOFTWARE
// OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

/*
This package provides an event-based IRC client library. It allows you to
register callbacks for the events you need to handle. Its features
include handling standard CTCP, reconnecting on errors, and detecting
stone servers.
Details of the IRC protocol can be found in the following RFCs:
https://tools.ietf.org/html/rfc1459
https://tools.ietf.org/html/rfc2810
https://tools.ietf.org/html/rfc2811
https://tools.ietf.org/html/rfc2812
https://tools.ietf.org/html/rfc2813
The details of the client-to-client protocol (CTCP) can be found here: http://www.irchelp.org/irchelp/rfc/ctcpspec.html
*/

package irc

import (
	"bufio"
	"bytes"
	"crypto/tls"
	"errors"
	"fmt"
	"log"
	"net"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"

	"golang.org/x/net/proxy"
	"golang.org/x/text/encoding"
	"h12.io/socks"
)

const (
	VERSION = "go-ircevent v2.1+myip"
)

const CAP_TIMEOUT = time.Second * 15

var ErrDisconnected = errors.New("Disconnect Called")

type socks4Dialer struct {
	dialFunc func(string, string) (net.Conn, error)
}

func (d *socks4Dialer) Dial(network, addr string) (net.Conn, error) {
	return d.dialFunc(network, addr)
}

// Read data from a connection. To be used as a goroutine.
func (irc *Connection) readLoop() {
	defer irc.Done()
	r := irc.Encoding.NewDecoder().Reader(irc.socket)
	br := bufio.NewReaderSize(r, 512)

	errChan := irc.ErrorChan()

	for {
		select {
		case <-irc.end:
			return
		default:
			// Set a read deadline based on the combined timeout and ping frequency
			// We should ALWAYS have received a response from the server within the timeout
			// after our own pings
			if irc.socket != nil {
				irc.socket.SetReadDeadline(time.Now().Add(irc.Timeout + irc.PingFreq))
			}

			msg, err := br.ReadString('\n')

			// We got past our blocking read, so clear timeout
			if irc.socket != nil {
				var zero time.Time
				irc.socket.SetReadDeadline(zero)
			}

			if err != nil {
				errChan <- err
				return
			}

			if irc.Debug {
				irc.Log.Printf("<-- %s\n", strings.TrimSpace(msg))
			}

			irc.lastMessageMutex.Lock()
			irc.lastMessage = time.Now()
			irc.lastMessageMutex.Unlock()
			event, err := parseToEvent(msg)
			if err == nil {
				event.Connection = irc
				if irc.HandleErrorAsDisconnect && strings.ToUpper(event.Code) == "ERROR" {
					errChan <- errors.New("Received ERROR from server: " + event.Message())
					return
				}
				irc.RunCallbacks(event)
			}
		}
	}
}

// Unescape tag values as defined in the IRCv3.2 message tags spec
// http://ircv3.net/specs/core/message-tags-3.2.html
func unescapeTagValue(value string) string {
	value = strings.Replace(value, "\\:", ";", -1)
	value = strings.Replace(value, "\\s", " ", -1)
	value = strings.Replace(value, "\\\\", "\\", -1)
	value = strings.Replace(value, "\\r", "\r", -1)
	value = strings.Replace(value, "\\n", "\n", -1)
	return value
}

// Parse raw IRC messages
func parseToEvent(msg string) (*Event, error) {
	msg = strings.TrimSuffix(msg, "\n") // Remove \r\n
	msg = strings.TrimSuffix(msg, "\r")
	event := &Event{Raw: msg}
	if len(msg) < 5 {
		return nil, errors.New("malformed msg from server")
	}

	if msg[0] == '@' {
		// IRCv3 Message Tags
		if i := strings.Index(msg, " "); i > -1 {
			event.Tags = make(map[string]string)
			tags := strings.Split(msg[1:i], ";")
			for _, data := range tags {
				parts := strings.SplitN(data, "=", 2)
				if len(parts) == 1 {
					event.Tags[parts[0]] = ""
				} else {
					event.Tags[parts[0]] = unescapeTagValue(parts[1])
				}
			}
			msg = msg[i+1:]
		} else {
			return nil, errors.New("malformed msg from server")
		}
	}

	if msg[0] == ':' {
		if i := strings.Index(msg, " "); i > -1 {
			event.Source = msg[1:i]
			msg = msg[i+1:]
		} else {
			return nil, errors.New("malformed msg from server")
		}

		if i, j := strings.Index(event.Source, "!"), strings.Index(event.Source, "@"); i > -1 && j > -1 && i < j {
			event.Nick = event.Source[0:i]
			event.User = event.Source[i+1 : j]
			event.Host = event.Source[j+1:]
		}
	}

	split := strings.SplitN(msg, " :", 2)
	args := strings.Split(split[0], " ")
	event.Code = strings.ToUpper(args[0])
	event.Arguments = args[1:]
	if len(split) > 1 {
		event.Arguments = append(event.Arguments, split[1])
	}
	return event, nil

}

// Loop to write to a connection. To be used as a goroutine.
func (irc *Connection) writeLoop() {
	defer irc.Done()
	w := irc.Encoding.NewEncoder().Writer(irc.socket)
	errChan := irc.ErrorChan()
	for {
		select {
		case <-irc.end:
			return
		case b, ok := <-irc.pwrite:
			if !ok || b == "" || irc.socket == nil {
				return
			}

			if irc.Debug {
				irc.Log.Printf("--> %s\n", strings.TrimSpace(b))
			}

			// Set a write deadline based on the timeout
			irc.socket.SetWriteDeadline(time.Now().Add(irc.Timeout))

			_, err := w.Write([]byte(b))

			// Clear the write deadline
			var zero time.Time
			irc.socket.SetWriteDeadline(zero)

			if err != nil {
				errChan <- err
				return
			}
		}
	}
}

// Pings the server if we have not received any messages for 5 minutes
// to keep the connection alive. To be used as a goroutine.
func (irc *Connection) pingLoop() {
	defer irc.Done()
	ticker := time.NewTicker(1 * time.Minute) // Tick every minute for monitoring
	ticker2 := time.NewTicker(irc.PingFreq)   // Tick at the ping frequency.
	for {
		select {
		case <-ticker.C:
			// Ping if we haven't received anything from the server within the keep-alive period
			irc.lastMessageMutex.Lock()
			if time.Since(irc.lastMessage) >= irc.KeepAlive {
				irc.SendRawf("PING %d", time.Now().UnixNano())
			}
			irc.lastMessageMutex.Unlock()
		case <-ticker2.C:
			// Ping at the ping frequency
			irc.SendRawf("PING %d", time.Now().UnixNano())
			// Try to recapture nickname if it's not as configured.
			irc.Lock()
			if irc.nick != irc.nickcurrent {
				irc.nickcurrent = irc.nick
				irc.SendRawf("NICK %s", irc.nick)
			}
			irc.Unlock()
		case <-irc.end:
			ticker.Stop()
			ticker2.Stop()
			return
		}
	}
}

func (irc *Connection) isQuitting() bool {
	irc.Lock()
	defer irc.Unlock()
	return irc.quit
}

// Main loop to control the connection.
func (irc *Connection) Loop() {
	errChan := irc.ErrorChan()
	for !irc.isQuitting() {
		err := <-errChan
		if irc.HandleErrorAsDisconnect && strings.HasPrefix(err.Error(), "Received ERROR from server:") {
			irc.Log.Printf("Received ERROR event, not attempting automatic reconnect.")
			return
		}
		if irc.end != nil {
			close(irc.end)
		}
		irc.Wait()
		for !irc.isQuitting() {
			irc.Log.Printf("Error, disconnected: %s\n", err)
			if err = irc.Reconnect(); err != nil {
				irc.Log.Printf("Error while reconnecting: %s\n", err)
				time.Sleep(60 * time.Second)
			} else {
				errChan = irc.ErrorChan()
				break
			}
		}
	}
}

// Quit the current connection and disconnect from the server
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.1.6
func (irc *Connection) Quit() {
	quit := "QUIT"

	if irc.QuitMessage != "" {
		quit = fmt.Sprintf("QUIT :%s", irc.QuitMessage)
	}

	irc.SendRaw(quit)
	irc.Lock()
	irc.stopped = true
	irc.quit = true
	irc.Unlock()
}

// Use the connection to join a given channel.
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.2.1
func (irc *Connection) Join(channel string) {
	irc.pwrite <- fmt.Sprintf("JOIN %s\r\n", channel)
}

// Leave a given channel.
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.2.2
func (irc *Connection) Part(channel string) {
	irc.pwrite <- fmt.Sprintf("PART %s\r\n", channel)
}

// Send a notification to a nickname. This is similar to Privmsg but must not receive replies.
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.4.2
func (irc *Connection) Notice(target, message string) {
	irc.pwrite <- fmt.Sprintf("NOTICE %s :%s\r\n", target, message)
}

// Send a formatted notification to a nickname.
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.4.2
func (irc *Connection) Noticef(target, format string, a ...interface{}) {
	irc.Notice(target, fmt.Sprintf(format, a...))
}

// Send (action) message to a target (channel or nickname).
// No clear RFC on this one...
func (irc *Connection) Action(target, message string) {
	irc.pwrite <- fmt.Sprintf("PRIVMSG %s :\001ACTION %s\001\r\n", target, message)
}

// Send formatted (action) message to a target (channel or nickname).
func (irc *Connection) Actionf(target, format string, a ...interface{}) {
	irc.Action(target, fmt.Sprintf(format, a...))
}

// Send (private) message to a target (channel or nickname).
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.4.1
func (irc *Connection) Privmsg(target, message string) {
	irc.pwrite <- fmt.Sprintf("PRIVMSG %s :%s\r\n", target, message)
}

// Send formatted string to specified target (channel or nickname).
func (irc *Connection) Privmsgf(target, format string, a ...interface{}) {
	irc.Privmsg(target, fmt.Sprintf(format, a...))
}

// Kick <user> from <channel> with <msg>. For no message, pass empty string ("")
func (irc *Connection) Kick(user, channel, msg string) {
	var cmd bytes.Buffer
	cmd.WriteString(fmt.Sprintf("KICK %s %s", channel, user))
	if msg != "" {
		cmd.WriteString(fmt.Sprintf(" :%s", msg))
	}
	cmd.WriteString("\r\n")
	irc.pwrite <- cmd.String()
}

// Kick all <users> from <channel> with <msg>. For no message, pass
// empty string ("")
func (irc *Connection) MultiKick(users []string, channel string, msg string) {
	var cmd bytes.Buffer
	cmd.WriteString(fmt.Sprintf("KICK %s %s", channel, strings.Join(users, ",")))
	if msg != "" {
		cmd.WriteString(fmt.Sprintf(" :%s", msg))
	}
	cmd.WriteString("\r\n")
	irc.pwrite <- cmd.String()
}

// Send raw string.
func (irc *Connection) SendRaw(message string) {
	irc.pwrite <- message + "\r\n"
}

// Send raw formatted string.
func (irc *Connection) SendRawf(format string, a ...interface{}) {
	irc.SendRaw(fmt.Sprintf(format, a...))
}

// Set (new) nickname.
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.1.2
func (irc *Connection) Nick(n string) {
	irc.nick = n
	irc.SendRawf("NICK %s", n)
}

// Determine nick currently used with the connection.
func (irc *Connection) GetNick() string {
	return irc.nickcurrent
}

// Query information about a particular nickname.
// RFC 1459: https://tools.ietf.org/html/rfc1459#section-4.5.2
func (irc *Connection) Whois(nick string) {
	irc.SendRawf("WHOIS %s", nick)
}

// Query information about a given nickname in the server.
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.5.1
func (irc *Connection) Who(nick string) {
	irc.SendRawf("WHO %s", nick)
}

// Set different modes for a target (channel or nickname).
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.2.3
func (irc *Connection) Mode(target string, modestring ...string) {
	if len(modestring) > 0 {
		mode := strings.Join(modestring, " ")
		irc.SendRawf("MODE %s %s", target, mode)
		return
	}
	irc.SendRawf("MODE %s", target)
}

func (irc *Connection) ErrorChan() chan error {
	return irc.Error
}

// Returns true if the connection is connected to an IRC server.
func (irc *Connection) Connected() bool {
	return !irc.stopped
}

// A disconnect sends all buffered messages (if possible),
// stops all goroutines and then closes the socket.
func (irc *Connection) Disconnect() {
	irc.Lock()
	irc.fullyConnected = false
	defer irc.Unlock()

	if irc.end != nil {
		close(irc.end)
	}

	irc.Wait()

	irc.end = nil

	if irc.pwrite != nil {
		close(irc.pwrite)
	}

	if irc.socket != nil {
		irc.socket.Close()
	}
	irc.ErrorChan() <- ErrDisconnected
}

// Reconnect to a server using the current connection.
func (irc *Connection) Reconnect() error {
	irc.Lock()
	irc.fullyConnected = false
	irc.Unlock()
	irc.end = make(chan struct{})
	return irc.Connect(irc.Server)
}

// Connect to a given server using the current connection configuration.
// This function also takes care of identification if a password is provided.
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.1
func (irc *Connection) Connect(server string) error {
	irc.Server = server
	// Mark Server as stopped since there can be an error during connect
	irc.stopped = true

	// Make sure everything is ready for connection
	if len(irc.Server) == 0 {
		return errors.New("empty 'server'")
	}
	if strings.Index(irc.Server, ":") == 0 {
		return errors.New("hostname is missing")
	}
	if strings.Index(irc.Server, ":") == len(irc.Server)-1 {
		return errors.New("port missing")
	}
	_, ports, err := net.SplitHostPort(irc.Server)
	if err != nil {
		return errors.New("wrong address string")
	}
	port, err := strconv.Atoi(ports)
	if err != nil {
		return errors.New("extracting port failed")
	}
	if !((port >= 0) && (port <= 65535)) {
		return errors.New("port number outside valid range")
	}
	if irc.Log == nil {
		return errors.New("'Log' points to nil")
	}
	if len(irc.nick) == 0 {
		return errors.New("empty 'nick'")
	}
	if len(irc.user) == 0 {
		return errors.New("empty 'user'")
	}

	var localAddr net.Addr
	if irc.localIP != "" {
		localAddr = &net.TCPAddr{
			IP:   net.ParseIP(irc.localIP),
			Port: 0,
		}
	}

	var dialer proxy.Dialer
	if irc.ProxyConfig != nil {
		switch irc.ProxyConfig.Type {
		case "socks4":
			socks4Proxy := socks.Dial(fmt.Sprintf("socks4://%s:%s@%s", irc.ProxyConfig.Username, irc.ProxyConfig.Password, irc.ProxyConfig.Address))
			dialer = &socks4Dialer{dialFunc: socks4Proxy}
		case "socks5":
			auth := &proxy.Auth{
				User:     irc.ProxyConfig.Username,
				Password: irc.ProxyConfig.Password,
			}
			socks5Proxy, err := proxy.SOCKS5("tcp", irc.ProxyConfig.Address, auth, proxy.Direct)
			if err != nil {
				return err
			}
			dialer = socks5Proxy
		case "http":
			proxyURL, err := url.Parse(fmt.Sprintf("http://%s:%s@%s", irc.ProxyConfig.Username, irc.ProxyConfig.Password, irc.ProxyConfig.Address))
			if err != nil {
				return err
			}
			httpProxy, err := proxy.FromURL(proxyURL, proxy.Direct)
			if err != nil {
				return err
			}
			dialer = httpProxy
		default:
			return fmt.Errorf("unsupported proxy type: %s", irc.ProxyConfig.Type)
		}
	} else {
		dialer = &net.Dialer{
			LocalAddr: localAddr,
			Timeout:   irc.Timeout,
		}
	}

	irc.socket, err = dialer.Dial("tcp", irc.Server)
	if err != nil {
		return err
	}
	if irc.UseTLS {
		irc.socket = tls.Client(irc.socket, irc.TLSConfig)
	}

	if irc.Encoding == nil {
		irc.Encoding = encoding.Nop
	}

	irc.stopped = false
	irc.Log.Printf("Connected to %s (%s)\n", irc.Server, irc.socket.RemoteAddr())

	irc.pwrite = make(chan string, 10)
	irc.Error = make(chan error, 10)
	irc.Add(3)
	go irc.readLoop()
	go irc.writeLoop()
	go irc.pingLoop()

	if len(irc.WebIRC) > 0 {
		irc.pwrite <- fmt.Sprintf("WEBIRC %s\r\n", irc.WebIRC)
	}

	if len(irc.Password) > 0 {
		irc.pwrite <- fmt.Sprintf("PASS %s\r\n", irc.Password)
	}

	err = irc.negotiateCaps()
	if err != nil {
		return err
	}

	realname := irc.user
	if irc.RealName != "" {
		realname = irc.RealName
	}

	irc.pwrite <- fmt.Sprintf("NICK %s\r\n", irc.nick)
	irc.pwrite <- fmt.Sprintf("USER %s 0.0.0.0 0.0.0.0 :%s\r\n", irc.user, realname)
	return nil
}

func (irc *Connection) SetProxy(proxyType, address, username, password string) {
	irc.ProxyConfig = &ProxyConfig{
		Type:     proxyType,
		Address:  address,
		Username: username,
		Password: password,
	}
}

// Negotiate IRCv3 capabilities
func (irc *Connection) negotiateCaps() error {
	irc.RequestCaps = nil
	irc.AcknowledgedCaps = nil

	var negotiationCallbacks []CallbackID
	defer func() {
		for _, callback := range negotiationCallbacks {
			irc.RemoveCallback(callback.EventCode, callback.ID)
		}
	}()

	saslResChan := make(chan *SASLResult)
	if irc.UseSASL {
		irc.RequestCaps = append(irc.RequestCaps, "sasl")
		negotiationCallbacks = irc.setupSASLCallbacks(saslResChan)
	}

	if len(irc.RequestCaps) == 0 {
		return nil
	}

	cap_chan := make(chan bool, len(irc.RequestCaps))
	id := irc.AddCallback("CAP", func(e *Event) {
		if len(e.Arguments) != 3 {
			return
		}
		command := e.Arguments[1]

		if command == "LS" {
			missing_caps := len(irc.RequestCaps)
			for _, cap_name := range strings.Split(e.Arguments[2], " ") {
				for _, req_cap := range irc.RequestCaps {
					if cap_name == req_cap {
						irc.pwrite <- fmt.Sprintf("CAP REQ :%s\r\n", cap_name)
						missing_caps--
					}
				}
			}

			for i := 0; i < missing_caps; i++ {
				cap_chan <- true
			}
		} else if command == "ACK" || command == "NAK" {
			for _, cap_name := range strings.Split(strings.TrimSpace(e.Arguments[2]), " ") {
				if cap_name == "" {
					continue
				}

				if command == "ACK" {
					irc.AcknowledgedCaps = append(irc.AcknowledgedCaps, cap_name)
				}
				cap_chan <- true
			}
		}
	})
	negotiationCallbacks = append(negotiationCallbacks, CallbackID{"CAP", id})

	irc.pwrite <- "CAP LS\r\n"

	if irc.UseSASL {
		select {
		case res := <-saslResChan:
			if res.Failed {
				return res.Err
			}
		case <-time.After(CAP_TIMEOUT):
			// Raise an error if we can't authenticate with SASL.
			return errors.New("SASL setup timed out. Does the server support SASL?")
		}
	}

	remaining_caps := len(irc.RequestCaps)

	select {
	case <-cap_chan:
		remaining_caps--
	case <-time.After(CAP_TIMEOUT):
		// The server probably doesn't implement CAP LS, which is "normal".
		return nil
	}

	// Wait for all capabilities to be ACKed or NAKed before ending negotiation
	for remaining_caps > 0 {
		<-cap_chan
		remaining_caps--
	}

	irc.pwrite <- "CAP END\r\n"

	return nil
}

// Create a connection with the (publicly visible) nickname and username.
// The nickname is later used to address the user. Returns nil if nick
// or user are empty.
func IRC(nick, user string) *Connection {
	// Catch invalid values
	if len(nick) == 0 {
		return nil
	}
	if len(user) == 0 {
		return nil
	}

	irc := &Connection{
		nick:                    nick,
		nickcurrent:             nick,
		user:                    user,
		Log:                     log.New(os.Stdout, "", log.LstdFlags),
		end:                     make(chan struct{}),
		Version:                 VERSION,
		KeepAlive:               4 * time.Minute,
		Timeout:                 1 * time.Minute,
		PingFreq:                15 * time.Minute,
		SASLMech:                "PLAIN",
		QuitMessage:             "",
		fullyConnected:          false,           // Initialize to false
		DCCManager:              NewDCCManager(), // DCC chat support
		ProxyConfig:             nil,
		HandleErrorAsDisconnect: true, // Default to true to not reconnect after ERROR event
	}
	irc.setupCallbacks()
	return irc
}

// SetLocalIP sets the local IP address to bind when connecting.
// This allows the client to specify which local interface/IP to use.
func (irc *Connection) SetLocalIP(ip string) {
	irc.localIP = ip
}

func (irc *Connection) IsFullyConnected() bool {
	irc.Lock()
	defer irc.Unlock()
	return irc.fullyConnected
}