source: code/trunk/server.go@ 8

package jounce

import (
        "fmt"
        "io"
        "log"
        "net"

        "gopkg.in/irc.v3"
)

type ircError struct {
        Message *irc.Message
}

func newUnknownCommandError(cmd string) ircError {
        return ircError{&irc.Message{
                Command: irc.ERR_UNKNOWNCOMMAND,
                Params: []string{
                        "*",
                        cmd,
                        "Unknown command",
                },
        }}
}

func newNeedMoreParamsError(cmd string) ircError {
        return ircError{&irc.Message{
                Command: irc.ERR_NEEDMOREPARAMS,
                Params: []string{
                        "*",
                        cmd,
                        "Not enough parameters",
                },
        }}
}

func (err ircError) Error() string {
        return err.Message.String()
}

type downstreamConn struct {
        net        net.Conn
        irc        *irc.Conn
        srv        *Server
        registered bool
        closed     bool
        nick       string
        username   string
        realname   string
}

func (c *downstreamConn) Close() error {
        if err := c.net.Close(); err != nil {
                return err
        }
        c.closed = true
        return nil
}

func (c *downstreamConn) WriteMessage(msg *irc.Message) error {
        msg.Prefix = c.srv.prefix()
        return c.irc.WriteMessage(msg)
}

func (c *downstreamConn) handleMessage(msg *irc.Message) error {
        switch msg.Command {
        case "PING":
                // TODO: handle params
                return c.WriteMessage(&irc.Message{
                        Command: "PONG",
                        Params: []string{c.srv.Hostname},
                })
        default:
                if c.registered {
                        return c.handleMessageRegistered(msg)
                } else {
                        return c.handleMessageUnregistered(msg)
                }
        }
}

func (c *downstreamConn) handleMessageUnregistered(msg *irc.Message) error {
        switch msg.Command {
        case "NICK":
                if len(msg.Params) != 1 {
                        return newNeedMoreParamsError(msg.Command)
                }
                c.nick = msg.Params[0]
        case "USER":
                if len(msg.Params) != 4 {
                        return newNeedMoreParamsError(msg.Command)
                }
                c.username = "~" + msg.Params[0]
                c.realname = msg.Params[3]
        case "QUIT":
                return c.Close()
        default:
                return newUnknownCommandError(msg.Command)
        }
        if c.username != "" && c.nick != "" {
                return c.register()
        }
        return nil
}

func (c *downstreamConn) register() error {
        c.registered = true

        err := c.WriteMessage(&irc.Message{
                Command: irc.RPL_WELCOME,
                Params:  []string{c.nick, "Welcome to jounce, " + c.nick},
        })
        if err != nil {
                return err
        }

        err = c.WriteMessage(&irc.Message{
                Command: irc.RPL_YOURHOST,
                Params:  []string{c.nick, "Your host is " + c.srv.Hostname},
        })
        if err != nil {
                return err
        }

        err = c.WriteMessage(&irc.Message{
                Command: irc.RPL_CREATED,
                Params:  []string{c.nick, "This server was created <datetime>"}, // TODO
        })
        if err != nil {
                return err
        }

        err = c.WriteMessage(&irc.Message{
                Command: irc.RPL_MYINFO,
                Params:  []string{c.nick, c.srv.Hostname, "unknown", "", ""},
        })
        if err != nil {
                return err
        }

        err = c.WriteMessage(&irc.Message{
                Command: irc.ERR_NOMOTD,
                Params: []string{c.nick, "No MOTD"},
        })
        if err != nil {
                return err
        }

        return nil
}

func (c *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
        switch msg.Command {
        case "NICK", "USER":
                return ircError{&irc.Message{
                        Command: irc.ERR_ALREADYREGISTERED,
                        Params: []string{
                                c.nick,
                                "You may not reregister",
                        },
                }}
        case "QUIT":
                return c.Close()
        default:
                return newUnknownCommandError(msg.Command)
        }
}

type Server struct{
        Hostname string
}

func (s *Server) prefix() *irc.Prefix {
        return &irc.Prefix{Name: s.Hostname}
}

func (s *Server) handleConn(netConn net.Conn) error {
        c := downstreamConn{net: netConn, irc: irc.NewConn(netConn), srv: s}
        defer c.Close()
        for {
                msg, err := c.irc.ReadMessage()
                if err == io.EOF {
                        break
                } else if err != nil {
                        return fmt.Errorf("failed to read IRC command: %v", err)
                }
                log.Println(msg)

                err = c.handleMessage(msg)
                if ircErr, ok := err.(ircError); ok {
                        ircErr.Message.Prefix = s.prefix()
                        if err := c.WriteMessage(ircErr.Message); err != nil {
                                return fmt.Errorf("failed to write IRC reply: %v", err)
                        }
                } else if err != nil {
                        return fmt.Errorf("failed to handle IRC command %q: %v", msg.Command, err)
                }

                if c.closed {
                        return nil
                }
        }

        return c.Close()
}

func (s *Server) Serve(ln net.Listener) error {
        for {
                c, err := ln.Accept()
                if err != nil {
                        return fmt.Errorf("failed to accept connection: %v", err)
                }

                go func() {
                        if err := s.handleConn(c); err != nil {
                                log.Printf("error handling connection: %v", err)
                        }
                }()
        }
}