irc-client/irc-client.go

package ircclient

import (
	"bufio"
	"crypto/tls"
	"crypto/x509"
	"encoding/base64"
	"fmt"
	"io"
	"log"
	"math/rand"
	"net"
	"os"
	"os/signal"
	"strconv"
	"strings"
	"syscall"
	"time"
)

type IRCMsg struct {
	MsgParts []string
	From     string
	To       string
	Cmd      string
	Msg      string
}

type IRCWrite struct {
	To     string
	Output string
}

type IRCConfig struct {
	Port           int
	Hostname       string
	UseTLS         bool // Use TLS Secure connection
	UseSASL        bool // Authenticate via SASL
	Insecure       bool // Allow self-signed certificates
	Nick           string
	MyNick         string
	Username       string
	Realname       string
	Password       string // Password for nickserv
	ServerPassword string // Password for server
	Socket         net.Conn
	TLSSocket      *tls.Conn
	Reader         *bufio.Reader
	ReadChannel    chan IRCMsg
	ReadEvents     []string
	WriteChannel   chan IRCWrite
	DelChannel     chan string
	Registered     bool
	Flood_Num      int // Number of lines sent before considered a flood
	Flood_Time     int // Number of Seconds to track previous messages
	Flood_Delay    int // Delay between sending when flood protection on (Milliseconds)
	OnExit         func()
}

// Writer       *bufio.Writer

func (Config *IRCConfig) Connect() bool {
	var err error

	if Config.Flood_Num == 0 {
		Config.Flood_Num = 5
	}
	if Config.Flood_Time == 0 {
		Config.Flood_Time = 10
	}

	if Config.Flood_Delay == 0 {
		Config.Flood_Delay = 1000
	}

	Config.Registered = false

	if Config.ReadChannel == nil {
		log.Println("Warning: ReadChannel is nil.")
	}

	if Config.UseTLS {
		var tlsConfig tls.Config

		if !Config.Insecure {
			certPool := x509.NewCertPool()
			tlsConfig.ClientCAs = certPool
			tlsConfig.InsecureSkipVerify = false
		} else {
			tlsConfig.InsecureSkipVerify = true
		}

		Config.TLSSocket, err = tls.Dial("tcp", Config.Hostname+":"+strconv.Itoa(Config.Port), &tlsConfig)
		if err != nil {
			log.Fatal("tls.Dial:", err)
		}
		// Config.Writer = bufio.NewWriter(Config.TLSSocket)
		Config.Reader = bufio.NewReader(Config.TLSSocket)
	} else {
		Config.Socket, err = net.Dial("tcp", Config.Hostname+":"+strconv.Itoa(Config.Port))
		if err != nil {
			log.Fatal("net.Dial:", err)
		}
		// Config.Writer = bufio.NewWriter(Config.Socket)
		Config.Reader = bufio.NewReader(Config.Socket)
	}

	Config.WriteChannel = make(chan IRCWrite)
	Config.DelChannel = make(chan string)

	// We are connected.
	go Config.WriterRoutine()

	// Registration
	if Config.UseTLS && Config.UseSASL {
		Config.PriorityWrite("CAP REQ :sasl")
	}

	if Config.ServerPassword != "" {
		Config.PriorityWrite(fmt.Sprintf("PASS %s", Config.ServerPassword))
	}

	// Register nick
	Config.MyNick = Config.Nick
	Config.PriorityWrite(fmt.Sprintf("NICK %s", Config.Nick))
	Config.PriorityWrite(fmt.Sprintf("USER %s 0 * :%s", Config.Username, Config.Realname))
	// Config.Writer.Flush()

	go Config.ReaderRoutine()
	return true
}

// Low level write to [TLS]Socket routine.
func (Config *IRCConfig) write(output string) error {
	var err error
	log.Println(">>", output)
	output += "\r\n"
	if Config.UseTLS {
		_, err = Config.TLSSocket.Write([]byte(output))
	} else {
		_, err = Config.Socket.Write([]byte(output))
	}
	return err
}

func (Config *IRCConfig) WriterRoutine() {
	var err error
	var throttle ThrottleBuffer
	var Flood FloodTrack

	throttle.init()

	Flood.Track = make([]time.Time, Config.Flood_Num)

	// signal handler
	var sigChannel chan os.Signal = make(chan os.Signal, 1)
	signal.Notify(sigChannel, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)

	// Change this into a select with timeout.
	// Timeout, if there's something to be buffered.

	for {
		if throttle.Life_sucks {
			select {
			case output := <-Config.WriteChannel:
				if output.To == "" {
					err = Config.write(output.Output)
					if err != nil {
						log.Println("Writer:", err)
					}
					continue
				}

				throttle.push(output.To, output.Output)

			case <-sigChannel:
				if Config.OnExit != nil {
					Config.OnExit()
				}
				os.Exit(2)

			case remove := <-Config.DelChannel:
				log.Printf("Remove: [%s]\n", remove)
				throttle.delete(remove)

			case <-time.After(time.Millisecond * time.Duration(Config.Flood_Delay)):
				// Send from the buffer
				// debugging the flood buffer
				// log.Printf("targets: %#v\n", targets)
				// log.Printf("last: %d\n", last)
				// log.Printf("buffer: %#v\n", buffer)

				var msg string = throttle.pop()
				err = Config.write(msg)
				if err != nil {
					log.Println("Writer:", err)
				}
			}
		} else {
			// Life is good.
			select {
			case <-sigChannel:
				if Config.OnExit != nil {
					Config.OnExit()
				}
				os.Exit(2)

			case output := <-Config.WriteChannel:
				if output.To == "" {
					err = Config.write(output.Output)
					if err != nil {
						log.Println("Writer:", err)
					}
					continue
				}
				if Flood.Pos > 0 {
					Flood.Expire(Config.Flood_Time)
				}
				if Flood.Pos == Config.Flood_Num {
					throttle.push(output.To, output.Output)
				} else {
					// Flood limits not reached
					Flood.Save()
					err = Config.write(output.Output)
					if err != nil {
						log.Println("Writer:", err)
					}
				}

			}
		}
	}

	log.Println("~WriterRoutine")
}

func (Config *IRCConfig) Close() {
	if Config.UseTLS {
		Config.TLSSocket.Close()
	} else {
		Config.Socket.Close()
	}
}

func IRCParse(line string) []string {
	var pos int = strings.Index(line, " :")
	var message string

	if pos != -1 {
		message = line[pos+2:]
		line = line[:pos]
	}
	var results []string
	results = strings.Split(line, " ")
	if message != "" {
		results = append(results, message)
	}
	return results
}

func IRCNick(from string) string {
	if from[0] == ':' {
		from = from[1:]
	}
	var pos int = strings.Index(from, "!")
	if pos != -1 {
		from = from[:pos]
	}
	return from
}

func RandomNick(nick string) string {
	var result string = nick + "-"
	result += strconv.Itoa(rand.Intn(1000))
	return result
}

func (Config *IRCConfig) PriorityWrite(output string) {
	Config.WriteChannel <- IRCWrite{To: "", Output: output}
}

func (Config *IRCConfig) WriteTo(to string, output string) {
	Config.WriteChannel <- IRCWrite{To: to, Output: output}
}

func (Config *IRCConfig) Msg(to string, message string) {
	Config.WriteTo(to, fmt.Sprintf("PRIVMSG %s :%s", to, message))
}

func (Config *IRCConfig) Notice(to string, message string) {
	Config.WriteTo(to, fmt.Sprintf("NOTICE %s :%s", to, message))
}

func (Config *IRCConfig) Action(to string, message string) {
	Config.WriteTo(to, fmt.Sprintf("PRIVMSG %s :\x01ACTION %s\x01", to, message))
}

func (Config *IRCConfig) ReaderRoutine() {
	for {
		var line string
		var err error
		var results []string

		line, err = Config.Reader.ReadString('\n')
		if err == nil {
			line = strings.Trim(line, "\r\n")
			log.Println("<< ", line)

			results = IRCParse(line)

			if results[1] == "433" {
				// Nick already in use!
				var newNick string = RandomNick(Config.Nick)
				Config.MyNick = newNick
				Config.PriorityWrite("NICK " + newNick)
			}

			if results[1] == "PRIVMSG" {
				// Is this an action?
				if len(results) >= 3 {
					if (results[3][0] == '\x01') && (results[3][len(results[3])-1] == '\x01') {
						// ACTION
						results[1] = "CTCP"
						results[3] = results[3][1 : len(results[3])-1]
						log.Println("CTCP:", results[3])

						// Process CTCP commands
						if strings.HasPrefix(results[3], "ACTION ") {
							results[1] = "ACTION"
							results[3] = results[3][7:]
						}

						if strings.HasPrefix(results[3], "PING ") {
							Config.WriteTo(IRCNick(results[0]),
								fmt.Sprintf("NOTICE %s :\x01PING %s\x01",
									IRCNick(results[0]),
									results[3][5:]))
						}

						if results[3] == "VERSION" {
							// Send version reply
							Config.WriteTo(IRCNick(results[0]),
								fmt.Sprintf("NOTICE %s :\x01VERSION red-green.com/irc-client 0.1\x01",
									IRCNick(results[0])))
						}

						if results[3] == "TIME" {
							// Send time reply
							var now time.Time = time.Now()
							Config.WriteTo(IRCNick(results[0]),
								fmt.Sprintf("NOTICE %s :\x01TIME %s\x01",
									IRCNick(results[0]),
									now.Format(time.ANSIC)))
						}

					}
				}
			}
		} else {
			// This is likely, 2022/04/05 10:11:41 ReadString: EOF
			if err != io.EOF {
				log.Println("ReadString:", err)
			}
			close(Config.ReadChannel)
			return
		}
		var msg IRCMsg = IRCMsg{MsgParts: results}
		if len(results) >= 3 {
			msg.From = IRCNick(results[0])
			msg.Cmd = results[1]
			msg.To = results[2]
			if len(results) >= 4 {
				msg.Msg = results[3]
			}
		} else {
			msg.Cmd = results[0]
		}

		// Answer PING/PONG immediately.
		if results[0] == "PING" {
			Config.PriorityWrite("PONG " + results[1])
		}

		if (msg.Cmd == "401") || (msg.Cmd == "404") {
			// No such nick/channel
			log.Printf("Remove %s from buffer.", msg.MsgParts[3])
			Config.DelChannel <- msg.MsgParts[3]
		}

		if !Config.Registered {
			// We're not registered yet

			// Answer the queries for SASL authentication
			if (msg.Cmd == "CAP") && (msg.Msg == "ACK") {
				Config.PriorityWrite("AUTHENTICATE PLAIN")
			}

			if (msg.MsgParts[0] == "AUTHENTICATE") && (msg.MsgParts[1] == "+") {
				var userpass string = fmt.Sprintf("\x00%s\x00%s", Config.Nick, Config.Password)
				var b64 string = base64.StdEncoding.EncodeToString([]byte(userpass))
				Config.PriorityWrite("AUTHENTICATE " + b64)
			}

			if msg.Cmd == "903" {
				// Success SASL
				Config.PriorityWrite("CAP END")
				Config.Registered = true
			}

			if msg.Cmd == "904" {
				// Failed SASL
				Config.PriorityWrite("CAP END")
				// Should we exit here?
			}

			/*
				2022/04/06 19:12:11 <<  :[email protected] NOTICE meow :This nickname is registered and protected.  If it is your
				2022/04/06 19:12:11 <<  :[email protected] NOTICE meow :nick, type /msg NickServ IDENTIFY password.  Otherwise,
				2022/04/06 19:12:11 <<  :[email protected] NOTICE meow :please choose a different nick.
			*/
			if (msg.From == "NickServ") && (msg.Cmd == "NOTICE") {
				if strings.Contains(msg.Msg, "IDENTIFY") {
					Config.PriorityWrite(fmt.Sprintf("NS IDENTIFY %s", Config.Password))
				}
				// :[email protected] NOTICE meow :Password accepted - you are now recognized.
			}

			if !Config.UseSASL && (msg.Cmd == "900") {
				Config.Registered = true
			}

		}

		// This is a better way of knowing when we've identified for services
		if (msg.Cmd == "MODE") && (msg.To == Config.MyNick) {
			// This should probably be look for + and contains "r"
			if (msg.Msg[0] == '+') && (strings.Contains(msg.Msg, "r")) {
				Config.ReadChannel <- IRCMsg{Cmd: "Identified"}
			}
		}

		if Config.ReadChannel != nil {
			Config.ReadChannel <- msg
		}

		if (msg.Cmd == "376") || (msg.Cmd == "422") {
			// End MOTD, or MOTD Missing
			var reg IRCMsg = IRCMsg{Cmd: "EndMOTD"}
			Config.ReadChannel <- reg
		}

	}
}