irc.go

// Copyright 2009 Thomas Jager <mail@jager.no>  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
This package provides an event based IRC client library. It allows to
register callbacks for the events you need to handle. Its features
include handling standard CTCP, reconnecting on errors and detecting
stones 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"
	"crypto/tls"
	"errors"
	"fmt"
	"log"
	"net"
	"os"
	"strconv"
	"strings"
	"time"
)

// The CTCP-VERSION reply that clients using this package will return.
const (
	VERSION = "Elemental-IRCd irc package 0.1"
)

// This is thrown when another goroutine calls Disconnect.
var ErrDisconnected = errors.New("Disconnect Called")

// Read data from a connection. To be used as a goroutine.
func (irc *Connection) readLoop() {
	defer irc.Done()
	br := bufio.NewReaderSize(irc.socket, 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 bin timeout
			if irc.socket != nil {
				var zero time.Time
				irc.socket.SetReadDeadline(zero)
			}

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

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

			irc.lastMessage = time.Now()
			msg = msg[:len(msg)-2] //Remove \r\n
			event := &Event{Raw: msg, Connection: irc}
			if msg[0] == ':' {
				if i := strings.Index(msg, " "); i > -1 {
					event.Source = msg[1:i]
					msg = msg[i+1:]

				} else {
					irc.Log.Printf("Misformed msg from server: %s\n", msg)
				}

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

			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])
			}

			/* XXX: len(args) == 0: args should be empty */
			irc.RunCallbacks(event)
		}
	}
}

// Loop to write to a connection. To be used as a goroutine.
func (irc *Connection) writeLoop() {
	defer irc.Done()
	errChan := irc.ErrorChan()
	for {
		select {
		case <-irc.end:
			return
		default:
			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 time out
			irc.socket.SetWriteDeadline(time.Now().Add(irc.Timeout))

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

			// Past blocking write, bin timeout
			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
			if time.Since(irc.lastMessage) >= irc.KeepAlive {
				irc.SendRawf("PING %d", time.Now().UnixNano())
			}
		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.
			if irc.nick != irc.nickcurrent {
				irc.nickcurrent = irc.nick
				irc.SendRawf("NICK %s", irc.nick)
			}
		case <-irc.end:
			ticker.Stop()
			ticker2.Stop()
			return
		}
	}
}

// Loop is the main loop to control the connection.
func (irc *Connection) Loop() {
	errChan := irc.ErrorChan()
	for !irc.stopped {
		err := <-errChan
		if irc.stopped {
			break
		}
		irc.Log.Printf("Error, disconnected: %s\n", err)
		for !irc.stopped {
			if err = irc.Reconnect(); err != nil {
				irc.Log.Printf("Error while reconnecting: %s\n", err)
				time.Sleep(1 * time.Second)
			} else {
				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() {
	irc.SendRaw("QUIT")
	irc.stopped = true
}

// Join uses 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)
}

// Part leaves 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)
}

// Notice send a notification to a nickname or channel. 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)
}

// Noticef sends a formated notification to a nickname or channel.
// 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...))
}

// Action sends a CTCP-ACTION (/me) 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)
}

// Actionf sends a CTCP-ACTION (/me) to a target (channel or nickname).
func (irc *Connection) Actionf(target, format string, a ...interface{}) {
	irc.Action(target, fmt.Sprintf(format, a...))
}

// Privmsg sends a 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)
}

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

// SendRaw sends a raw message across the wire.
func (irc *Connection) SendRaw(message string) {
	irc.pwrite <- message + "\r\n"
}

// SendRawf sends a formatted raw message across the wire.
func (irc *Connection) SendRawf(format string, a ...interface{}) {
	irc.SendRaw(fmt.Sprintf(format, a...))
}

// Nick changes the client nickname to the given value. This may fail, causing the server to return
// ERR_NICKNAMEINUSE or ERR_ERRONEUSNICKNAME.
// 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)
}

// GetNick returns the nickname in use by the client.
func (irc *Connection) GetNick() string {
	return irc.nickcurrent
}

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

// Who fetches detailed information about a given target (nick or channel).
// RFC 1459 details: https://tools.ietf.org/html/rfc1459#section-4.5.1
func (irc *Connection) Who(target string) {
	irc.SendRawf("WHO %s", target)
}

// Mode sets 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)
}

// ErrorChan returns the connections error channel.
func (irc *Connection) ErrorChan() chan error {
	return irc.Error
}

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

// Disconnect sends all buffered messages (if possible),
// stops all goroutines and then closes the socket.
func (irc *Connection) Disconnect() {
	for event := range irc.events {
		irc.ClearCallback(event)
	}

	close(irc.end)
	close(irc.pwrite)

	irc.Wait()
	irc.socket.Close()
	irc.socket = nil
	irc.ErrorChan() <- ErrDisconnected
}

// Reconnect to a server using the current connection.
func (irc *Connection) Reconnect() error {
	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
	irc.stopped = false

	// make sure everything is ready for connection
	if len(irc.Server) == 0 {
		return errors.New("empty 'server'")
	}
	if strings.Count(irc.Server, ":") != 1 {
		return errors.New("wrong number of ':' in address")
	}
	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")
	}
	// check for valid range
	ports := strings.Split(irc.Server, ":")[1]
	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'")
	}

	if irc.UseTLS {
		dialer := &net.Dialer{Timeout: irc.Timeout}
		irc.socket, err = tls.DialWithDialer(dialer, "tcp", irc.Server, irc.TLSConfig)
	} else {
		irc.socket, err = net.DialTimeout("tcp", irc.Server, irc.Timeout)
	}
	if err != nil {
		return err
	}
	irc.Log.Printf("Connected to %s (%s)\n", irc.Server, irc.socket.RemoteAddr())

	irc.pwrite = make(chan string, 10)
	irc.Error = make(chan error, 2)
	irc.Add(3)
	go irc.readLoop()
	go irc.writeLoop()
	go irc.pingLoop()
	if len(irc.Password) > 0 {
		irc.pwrite <- fmt.Sprintf("PASS %s\r\n", irc.Password)
	}
	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, irc.user)
	return nil
}

// New creates 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 New(nick, user string) *Connection {
	// catch invalid values
	if len(nick) == 0 {
		return nil
	}
	if len(user) == 0 {
		return nil
	}

	irc := &Connection{
		nick:      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,
	}
	irc.setupCallbacks()
	return irc
}