diff --git a/src/irc/channel.go b/src/irc/channel.go
new file mode 100644
index 00000000..48c810e7
--- /dev/null
+++ b/src/irc/channel.go
@@ -0,0 +1,94 @@
+package irc
+
+type Channel struct {
+	name       string
+	key        string
+	topic      string
+	members    ClientSet
+	inviteOnly bool
+	invites    map[string]bool
+	server     *Server
+}
+
+type ChannelSet map[*Channel]bool
+
+func NewChannel(s *Server, name string) *Channel {
+	return &Channel{name: name, members: make(ClientSet), invites: make(map[string]bool), server: s}
+}
+
+func (ch *Channel) Send(reply Reply, fromClient *Client) {
+	for client := range ch.members {
+		if client != fromClient {
+			client.send <- reply
+		}
+	}
+}
+
+// channel functionality
+
+func (ch *Channel) Join(cl *Client, key string) {
+	if ch.key != key {
+		cl.send <- ErrInviteOnlyChannel(ch)
+		return
+	}
+
+	if ch.inviteOnly && !ch.invites[cl.nick] {
+		cl.send <- ErrBadChannelKey(ch)
+		return
+	}
+
+	ch.members[cl] = true
+	cl.channels[ch] = true
+
+	ch.Send(RplJoin(ch, cl), nil)
+	ch.GetTopic(cl)
+
+	for member := range ch.members {
+		cl.send <- RplNamReply(ch, member)
+	}
+	cl.send <- RplEndOfNames(ch.server)
+}
+
+func (ch *Channel) Part(cl *Client, message string) {
+	if !ch.members[cl] {
+		cl.send <- ErrNotOnChannel(ch)
+		return
+	}
+
+	delete(ch.members, cl)
+	delete(cl.channels, ch)
+
+	ch.Send(RplPart(ch, cl, message), nil)
+}
+
+func (ch *Channel) PrivMsg(cl *Client, message string) {
+	ch.Send(RplPrivMsgChannel(ch, cl, message), cl)
+}
+
+func (ch *Channel) GetTopic(cl *Client) {
+	if !ch.members[cl] {
+		cl.send <- ErrNotOnChannel(ch)
+		return
+	}
+
+	if ch.topic != "" {
+		cl.send <- RplTopic(ch)
+	} else {
+		cl.send <- RplNoTopic(ch)
+	}
+}
+
+func (ch *Channel) ChangeTopic(cl *Client, newTopic string) {
+	if !ch.members[cl] {
+		cl.send <- ErrNotOnChannel(ch)
+		return
+	}
+
+	ch.topic = newTopic
+
+	if ch.topic != "" {
+		ch.Send(RplTopic(ch), nil)
+	} else {
+		ch.Send(RplNoTopic(ch), nil)
+	}
+}
diff --git a/src/irc/client.go b/src/irc/client.go
index 85ad6284..250c6b5a 100644
--- a/src/irc/client.go
+++ b/src/irc/client.go
@@ -3,34 +3,46 @@ package irc
 import (
 	"fmt"
 	"net"
-	"strings"
 )
 
 type Client struct {
 	conn       net.Conn
-	send       chan<- string
+	hostname   string
+	send       chan<- Reply
 	recv       <-chan string
 	username   string
 	realname   string
 	nick       string
 	registered bool
 	invisible  bool
+	channels   ChannelSet
 }
 
+type ClientSet map[*Client]bool
+
 func NewClient(conn net.Conn) *Client {
-	client := new(Client)
-	client.conn = conn
-	client.send = StringWriteChan(conn)
-	client.recv = StringReadChan(conn)
+	client := &Client{conn: conn, recv: StringReadChan(conn), channels: make(ChannelSet), hostname: LookupHostname(conn.RemoteAddr())}
+	client.SetReplyToStringChan()
 	return client
 }
 
+func (c *Client) SetReplyToStringChan() {
+	send := make(chan Reply)
+	write := StringWriteChan(c.conn)
+	go func() {
+		for reply := range send {
+			write <- reply.String(c)
+		}
+	}()
+	c.send = send
+}
+
 // Adapt `chan string` to a `chan Message`.
-func (c *Client) Communicate(server chan<- *ClientMessage) {
+func (c *Client) Communicate(server *Server) {
 	for str := range c.recv {
 		m := ParseMessage(str)
 		if m != nil {
-			server <- &ClientMessage{c, m}
+			server.recv <- &ClientMessage{c, m}
 		}
 	}
 }
@@ -39,7 +51,7 @@ func (c *Client) Nick() string {
 	if c.nick != "" {
 		return c.nick
 	}
-	return "<guest>"
+	return "*"
 }
 
 func (c *Client) UModeString() string {
@@ -57,15 +69,10 @@ func (c *Client) HasUser() bool {
 	return c.username != ""
 }
 
-func (c *Client) Hostname() string {
-	addr := c.conn.RemoteAddr().String()
-	index := strings.LastIndex(addr, ":")
-	if index != -1 {
-		return addr[0:index]
-	}
-	return addr
+func (c *Client) UserHost() string {
+	return fmt.Sprintf("%s!%s@%s", c.nick, c.username, c.hostname)
 }
 
-func (c *Client) UserHost() string {
-	return fmt.Sprintf("%s!%s@%s", c.nick, c.username, c.Hostname())
+func (c *Client) Id() string {
+	return c.UserHost()
 }
diff --git a/src/irc/commands.go b/src/irc/commands.go
index 34bc8a96..6039a8fe 100644
--- a/src/irc/commands.go
+++ b/src/irc/commands.go
@@ -4,68 +4,180 @@ type Message interface {
 	Handle(s *Server, c *Client)
 }
 
-func (m *NickMessage) Handle(s *Server, c *Client) {
-	if s.nicks[m.nickname] != nil {
-		c.send <- ErrNickNameInUse(m.nickname)
-		return
-	}
-	oldNick := c.nick
-	if c.nick != "" {
-		delete(s.nicks, c.nick)
-	}
-	c.nick = m.nickname
-	s.nicks[c.nick] = c
-	if c.registered {
-		c.send <- ReplyNick(oldNick, c)
-	} else {
-		tryRegister(s, c)
-	}
-}
+// unknown
 
-func (m *UserMessage) Handle(s *Server, c *Client) {
-	if c.username != "" {
-		c.send <- ErrAlreadyRegistered(c.Nick())
-		return
-	}
-	c.username, c.realname = m.user, m.realname
-	tryRegister(s, c)
-}
-
-func (m *QuitMessage) Handle(s *Server, c *Client) {
-	c.send <- MessageError()
-	c.conn.Close()
-	delete(s.nicks, c.nick)
+type UnknownMessage struct {
+	command string
 }
 
 func (m *UnknownMessage) Handle(s *Server, c *Client) {
-	c.send <- ErrUnknownCommand(c.Nick(), m.command)
+	c.send <- ErrUnknownCommand(s, m.command)
+}
+
+// PING
+
+type PingMessage struct {
+	server  string
+	server2 string
 }
 
 func (m *PingMessage) Handle(s *Server, c *Client) {
-	c.send <- MessagePong()
+	c.send <- RplPong(s)
+}
+
+// PONG
+
+type PongMessage struct {
+	server1 string
+	server2 string
+}
+
+func (m *PongMessage) Handle(s *Server, c *Client) {
+	// TODO update client atime
+}
+
+// NICK
+
+type NickMessage struct {
+	nickname string
+}
+
+func (m *NickMessage) Handle(s *Server, c *Client) {
+	s.ChangeNick(c, m.nickname)
+}
+
+// USER
+
+type UserMessage struct {
+	user     string
+	mode     uint8
+	unused   string
+	realname string
+}
+
+func (m *UserMessage) Handle(s *Server, c *Client) {
+	s.Register(c, m.user, m.realname)
+}
+
+// QUIT
+
+type QuitMessage struct {
+	message string
+}
+
+func (m *QuitMessage) Handle(s *Server, c *Client) {
+	s.Quit(c, m.message)
+}
+
+// MODE
+
+type ModeMessage struct {
+	nickname string
+	modes    []string
 }
 
 func (m *ModeMessage) Handle(s *Server, c *Client) {
 	if m.nickname != c.nick {
-		c.send <- ErrUsersDontMatch(c.Nick())
+		c.send <- ErrUsersDontMatch(s)
 		return
 	}
-	for _, mode := range m.modes {
-		if mode == "+i" {
-			c.invisible = true
-		} else if mode == "-i" {
-			c.invisible = false
-		}
-	}
-	c.send <- ReplyUModeIs(c)
+	s.ChangeUserMode(c, m.modes)
 }
 
-func tryRegister(s *Server, c *Client) {
-	if (!c.registered && c.HasNick() && c.HasUser()) {
-		c.registered = true
-		c.send <- ReplyWelcome(c)
-		c.send <- ReplyYourHost(c.Nick(), s.name)
-		c.send <- ReplyCreated(c.Nick(), s.ctime)
-		c.send <- ReplyMyInfo(c.Nick(), s.name)
+// JOIN
+
+type JoinMessage struct {
+	channels []string
+	keys     []string
+	zero     bool
+}
+
+func (m *JoinMessage) Handle(s *Server, c *Client) {
+	if m.zero {
+		for channel := range c.channels {
+			channel.Part(c, "")
+		}
+	} else {
+		for i, name := range m.channels {
+			key := ""
+			if len(m.keys) > i {
+				key = m.keys[i]
+			}
+
+			s.GetOrMakeChannel(name).Join(c, key)
+		}
+	}
+}
+
+// PART
+
+type PartMessage struct {
+	channels []string
+	message  string
+}
+
+func (m *PartMessage) Handle(s *Server, c *Client) {
+	for _, chname := range m.channels {
+		channel := s.channels[chname]
+
+		if channel == nil {
+			c.send <- ErrNoSuchChannel(s, chname)
+			continue
+		}
+
+		channel.Part(c, m.message)
+	}
+}
+
+// PRIVMSG
+
+type PrivMsgMessage struct {
+	target  string
+	message string
+}
+
+func (m *PrivMsgMessage) TargetIsChannel() bool {
+	switch m.target[0] {
+	case '&', '#', '+', '!':
+		return true
+	}
+	return false
+}
+
+func (m *PrivMsgMessage) Handle(s *Server, c *Client) {
+	if m.TargetIsChannel() {
+		channel := s.channels[m.target]
+		if channel != nil {
+			channel.PrivMsg(c, m.message)
+		} else {
+			c.send <- ErrNoSuchNick(s, m.target)
+		}
+	} else {
+		client := s.nicks[m.target]
+		if client != nil {
+			client.send <- RplPrivMsg(client, m.message)
+		} else {
+			c.send <- ErrNoSuchNick(s, m.target)
+		}
+	}
+}
+
+// TOPIC
+
+type TopicMessage struct {
+	channel string
+	topic   string
+}
+
+func (m *TopicMessage) Handle(s *Server, c *Client) {
+	channel := s.channels[m.channel]
+	if channel == nil {
+		c.send <- ErrNoSuchChannel(s, m.channel)
+		return
+	}
+	if m.topic == "" {
+		channel.GetTopic(c)
+	} else {
+		channel.ChangeTopic(c, m.topic)
 	}
 }
diff --git a/src/irc/constants.go b/src/irc/constants.go
index 1a1b3a25..a0ce3bf7 100644
--- a/src/irc/constants.go
+++ b/src/irc/constants.go
@@ -1,4 +1,6 @@
-// http://tools.ietf.org/html/rfc2812
+// channel management: http://tools.ietf.org/html/rfc2811
+// client protocol:    http://tools.ietf.org/html/rfc2812
+// server protocol:    http://tools.ietf.org/html/rfc2813
 package irc
 
 const (
@@ -6,22 +8,30 @@ const (
 )
 
 const (
-	RPL_WELCOME  = "001"
-	RPL_YOURHOST = "002"
-	RPL_CREATED  = "003"
-	RPL_MYINFO   = "004"
-	RPL_UMODEIS  = "221"
-	RPL_INFO     = "371"
-	RPL_NICK     = "NICK"
-)
-
-const (
-	ERR_NOSUCHNICK       = "401"
-	ERR_NOSUCHSERVER     = "402"
-	ERR_NOSUCHCHANNEL    = "403"
-	ERR_UNKNOWNCOMMAND   = "421"
-	ERR_NICKNAMEINUSE    = "433"
-	ERR_NEEDMOREPARAMS   = "461"
-	ERR_ALREADYREGISTRED = "462"
-	ERR_USERSDONTMATCH   = "502"
+	RPL_WELCOME           = "001"
+	RPL_YOURHOST          = "002"
+	RPL_CREATED           = "003"
+	RPL_MYINFO            = "004"
+	RPL_UMODEIS           = "221"
+	RPL_NOTOPIC           = "331"
+	RPL_TOPIC             = "332"
+	RPL_NAMREPLY          = "353"
+	RPL_ENDOFNAMES        = "366"
+	RPL_INFO              = "371"
+	ERR_NOSUCHNICK        = "401"
+	ERR_NOSUCHSERVER      = "402"
+	ERR_NOSUCHCHANNEL     = "403"
+	ERR_UNKNOWNCOMMAND    = "421"
+	ERR_NICKNAMEINUSE     = "433"
+	ERR_NOTONCHANNEL      = "442"
+	ERR_NEEDMOREPARAMS    = "461"
+	ERR_ALREADYREGISTRED  = "462"
+	ERR_INVITEONLYCHANNEL = "473"
+	ERR_BADCHANNELKEY     = "475"
+	ERR_USERSDONTMATCH    = "502"
+	RPL_JOIN              = "JOIN"
+	RPL_NICK              = "NICK"
+	RPL_PART              = "PART"
+	RPL_PONG              = "PONG"
+	RPL_PRIVMSG           = "PRIVMSG"
 )
diff --git a/src/irc/message.go b/src/irc/message.go
deleted file mode 100644
index c3a7e944..00000000
--- a/src/irc/message.go
+++ /dev/null
@@ -1,27 +0,0 @@
-package irc
-
-type NickMessage struct {
-	nickname string
-}
-
-type UserMessage struct {
-	user string
-	mode uint8
-	unused string
-	realname string
-}
-
-type QuitMessage struct {
-	message string
-}
-
-type UnknownMessage struct {
-	command string
-}
-
-type PingMessage struct {}
-
-type ModeMessage struct {
-	nickname string
-	modes []string
-}
diff --git a/src/irc/net.go b/src/irc/net.go
index ca70c06e..c546e201 100644
--- a/src/irc/net.go
+++ b/src/irc/net.go
@@ -3,8 +3,8 @@ package irc
 import (
 	"bufio"
 	"log"
-	"strings"
 	"net"
+	"strings"
 )
 
 func readTrimmedLine(reader *bufio.Reader) (string, error) {
@@ -20,7 +20,7 @@ func StringReadChan(conn net.Conn) <-chan string {
 	go func() {
 		for {
 			line, err := readTrimmedLine(reader)
-			if (line != "") {
+			if line != "" {
 				ch <- line
 				log.Printf("%s -> %s", addr, line)
 			}
@@ -50,3 +50,16 @@ func StringWriteChan(conn net.Conn) chan<- string {
 
 	return ch
 }
+
+func LookupHostname(addr net.Addr) string {
+	addrStr := addr.String()
+	ipaddr, _, err := net.SplitHostPort(addrStr)
+	if err != nil {
+		return addrStr
+	}
+	names, err := net.LookupAddr(ipaddr)
+	if err != nil {
+		return ipaddr
+	}
+	return names[0]
+}
diff --git a/src/irc/parse.go b/src/irc/parse.go
index 3fcda8e4..3c85f184 100644
--- a/src/irc/parse.go
+++ b/src/irc/parse.go
@@ -7,12 +7,17 @@ import (
 	"strings"
 )
 
-var commands = map[string]func([]string) Message {
-	"MODE": NewModeMessage,
-	"NICK": NewNickMessage,
-	"PING": NewPingMessage,
-	"QUIT": NewQuitMessage,
-	"USER": NewUserMessage,
+var commands = map[string]func([]string) Message{
+	"JOIN":    NewJoinMessage,
+	"MODE":    NewModeMessage,
+	"NICK":    NewNickMessage,
+	"PART":    NewPartMessage,
+	"PING":    NewPingMessage,
+	"PONG":    NewPongMessage,
+	"PRIVMSG": NewPrivMsgMessage,
+	"QUIT":    NewQuitMessage,
+	"TOPIC":   NewTopicMessage,
+	"USER":    NewUserMessage,
 }
 
 func ParseMessage(line string) Message {
@@ -54,7 +59,6 @@ func parseLine(line string) (string, []string) {
 	return args[0], args[1:]
 }
 
-
 // []string => Message constructors
 
 func NewNickMessage(args []string) Message {
@@ -65,7 +69,25 @@ func NewNickMessage(args []string) Message {
 }
 
 func NewPingMessage(args []string) Message {
-	return &PingMessage{}
+	if len(args) < 1 {
+		return nil
+	}
+	message := &PingMessage{server: args[0]}
+	if len(args) > 1 {
+		message.server2 = args[1]
+	}
+	return message
+}
+
+func NewPongMessage(args []string) Message {
+	if len(args) < 1 {
+		return nil
+	}
+	message := &PongMessage{server1: args[0]}
+	if len(args) > 1 {
+		message.server2 = args[1]
+	}
+	return message
 }
 
 func NewQuitMessage(args []string) Message {
@@ -112,3 +134,55 @@ func NewModeMessage(args []string) Message {
 	}
 	return msg
 }
+
+func NewJoinMessage(args []string) Message {
+	msg := new(JoinMessage)
+
+	if len(args) > 0 {
+		if args[0] == "0" {
+			msg.zero = true
+		} else {
+			msg.channels = strings.Split(args[0], ",")
+		}
+
+		if len(args) > 1 {
+			msg.keys = strings.Split(args[1], ",")
+		}
+	}
+
+	return msg
+}
+
+func NewPartMessage(args []string) Message {
+	if len(args) < 1 {
+		return nil
+	}
+	msg := new(PartMessage)
+	msg.channels = strings.Split(args[0], ",")
+
+	if len(args) > 1 {
+		msg.message = args[1]
+	}
+
+	return msg
+}
+
+func NewPrivMsgMessage(args []string) Message {
+	if len(args) < 2 {
+		return nil
+	}
+
+	return &PrivMsgMessage{target: args[0], message: args[1]}
+}
+
+func NewTopicMessage(args []string) Message {
+	if len(args) < 1 {
+		return nil
+	}
+
+	message := &TopicMessage{channel: args[0]}
+	if len(args) > 1 {
+		message.topic = args[1]
+	}
+	return message
+}
diff --git a/src/irc/reply.go b/src/irc/reply.go
new file mode 100644
index 00000000..b4ee85bc
--- /dev/null
+++ b/src/irc/reply.go
@@ -0,0 +1,148 @@
+package irc
+
+import (
+	"fmt"
+	"time"
+)
+
+type Identifier interface {
+	Id() string
+}
+
+type Reply interface {
+	String(client *Client) string
+}
+
+type BasicReply struct {
+	source  Identifier
+	code    string
+	message string
+}
+
+func (reply *BasicReply) String(client *Client) string {
+	prefix := fmt.Sprintf(":%s %s %s ", reply.source.Id(), reply.code, client.Nick())
+	return prefix + reply.message
+}
+
+type ChannelReply struct {
+	*BasicReply
+	channel *Channel
+}
+
+func (reply *ChannelReply) String(client *Client) string {
+	prefix := fmt.Sprintf(":%s %s %s ", reply.source.Id(), reply.code, reply.channel.name)
+	return prefix + reply.message
+}
+
+func NewReply(source Identifier, code string, message string) *BasicReply {
+	return &BasicReply{source, code, message}
+}
+
+// messaging
+
+func RplPrivMsg(source *Client, message string) Reply {
+	return NewReply(source, RPL_PRIVMSG, ":"+message)
+}
+
+func RplNick(client *Client, newNick string) Reply {
+	return NewReply(client, RPL_NICK, ":"+newNick)
+}
+
+func RplPrivMsgChannel(channel *Channel, source *Client, message string) Reply {
+	return &ChannelReply{NewReply(source, RPL_PRIVMSG, ":"+message), channel}
+}
+
+func RplJoin(channel *Channel, client *Client) Reply {
+	return &ChannelReply{NewReply(client, RPL_JOIN, channel.name), channel}
+}
+
+func RplPart(channel *Channel, client *Client, message string) Reply {
+	return &ChannelReply{NewReply(client, RPL_PART, ":"+message), channel}
+}
+
+// Server Info
+
+func RplWelcome(source Identifier, client *Client) Reply {
+	return NewReply(source, RPL_WELCOME, "Welcome to the Internet Relay Network "+client.Id())
+}
+
+func RplYourHost(server *Server, target *Client) Reply {
+	return NewReply(server, RPL_YOURHOST, fmt.Sprintf("Your host is %s, running version %s", server.hostname, VERSION))
+}
+
+func RplCreated(server *Server) Reply {
+	return NewReply(server, RPL_CREATED, "This server was created "+server.ctime.Format(time.RFC1123))
+}
+
+func RplMyInfo(server *Server) Reply {
+	return NewReply(server, RPL_MYINFO, server.name+" i ik")
+}
+
+func RplUModeIs(server *Server, client *Client) Reply {
+	return NewReply(server, RPL_UMODEIS, client.UModeString())
+}
+
+// channel operations
+
+func RplNoTopic(channel *Channel) Reply {
+	return &ChannelReply{NewReply(channel.server, RPL_NOTOPIC, channel.name+" :No topic is set"), channel}
+}
+
+func RplTopic(channel *Channel) Reply {
+	return &ChannelReply{NewReply(channel.server, RPL_TOPIC, fmt.Sprintf("%s :%s", channel.name, channel.topic)), channel}
+}
+
+func RplNamReply(channel *Channel, client *Client) Reply {
+	// TODO multiple names and splitting based on message size
+	return NewReply(channel.server, RPL_NAMREPLY, fmt.Sprintf("=%s :+%s", channel.name, client.Nick()))
+}
+
+func RplEndOfNames(source Identifier) Reply {
+	return NewReply(source, RPL_ENDOFNAMES, ":End of NAMES list")
+}
+
+func RplPong(server *Server) Reply {
+	return NewReply(server, RPL_PONG, "")
+}
+
+// errors
+
+func ErrAlreadyRegistered(source Identifier) Reply {
+	return NewReply(source, ERR_ALREADYREGISTRED, ":You may not reregister")
+}
+
+func ErrNickNameInUse(source Identifier, nick string) Reply {
+	return NewReply(source, ERR_NICKNAMEINUSE, nick+" :Nickname is already in use")
+}
+
+func ErrUnknownCommand(source Identifier, command string) Reply {
+	return NewReply(source, ERR_UNKNOWNCOMMAND, command+" :Unknown command")
+}
+
+func ErrUsersDontMatch(source Identifier) Reply {
+	return NewReply(source, ERR_USERSDONTMATCH, ":Cannot change mode for other users")
+}
+
+func ErrNeedMoreParams(source Identifier, command string) Reply {
+	return NewReply(source, ERR_NEEDMOREPARAMS, command+"%s :Not enough parameters")
+}
+
+func ErrNoSuchChannel(source Identifier, channel string) Reply {
+	return NewReply(source, ERR_NOSUCHCHANNEL, channel+" :No such channel")
+}
+
+func ErrNotOnChannel(channel *Channel) Reply {
+	return NewReply(channel.server, ERR_NOTONCHANNEL, channel.name+" :You're not on that channel")
+}
+
+func ErrInviteOnlyChannel(channel *Channel) Reply {
+	return NewReply(channel.server, ERR_INVITEONLYCHANNEL, channel.name+" :Cannot join channel (+i)")
+}
+
+func ErrBadChannelKey(channel *Channel) Reply {
+	return NewReply(channel.server, ERR_BADCHANNELKEY, channel.name+" :Cannot join channel (+k)")
+}
+
+func ErrNoSuchNick(source Identifier, nick string) Reply {
+	return NewReply(source, ERR_NOSUCHNICK, nick+" :No such nick/channel")
+}
diff --git a/src/irc/responses.go b/src/irc/responses.go
deleted file mode 100644
index b9a26206..00000000
--- a/src/irc/responses.go
+++ /dev/null
@@ -1,54 +0,0 @@
-package irc
-
-import (
-	"fmt"
-	"time"
-)
-
-func ReplyNick(oldNick string, c *Client) string {
-	return fmt.Sprintf(":%s!%s@%s %s :%s", oldNick, c.username, c.Hostname(), RPL_NICK, c.Nick())
-}
-
-func ReplyWelcome(c *Client) string {
-	return fmt.Sprintf("%s %s Welcome to the Internet Relay Network %s!%s@%s", RPL_WELCOME, c.Nick(), c.Nick(), c.username, c.Hostname())
-}
-
-func ReplyYourHost(nick string, server string) string {
-	return fmt.Sprintf("%s %s Your host is %s, running version %s", RPL_YOURHOST, nick, server, VERSION)
-}
-
-func ReplyCreated(nick string, ctime time.Time) string {
-	return fmt.Sprintf("%s %s This server was created %s", RPL_CREATED, nick, ctime.Format(time.RFC1123))
-}
-
-func ReplyMyInfo(nick string, servername string) string {
-	return fmt.Sprintf("%s %s %s %s i <channel modes>", RPL_MYINFO, nick, servername, VERSION)
-}
-
-func ReplyUModeIs(c *Client) string {
-	return fmt.Sprintf("%s %s %s", RPL_UMODEIS, c.Nick(), c.UModeString())
-}
-
-func ErrAlreadyRegistered(nick string) string {
-	return fmt.Sprintf("%s %s :You may not reregister", ERR_ALREADYREGISTRED, nick)
-}
-
-func ErrNickNameInUse(nick string) string {
-	return fmt.Sprintf("%s %s :Nickname is already in use", ERR_NICKNAMEINUSE, nick)
-}
-
-func ErrUnknownCommand(nick string, command string) string {
-	return fmt.Sprintf("%s %s %s :Unknown command", ERR_UNKNOWNCOMMAND, nick, command)
-}
-
-func ErrUsersDontMatch(nick string) string {
-	return fmt.Sprintf("%s %s :Cannot change mode for other users", ERR_USERSDONTMATCH, nick)
-}
-
-func MessagePong() string {
-	return "PONG"
-}
-
-func MessageError() string {
-	return "ERROR :Bye"
-}
diff --git a/src/irc/server.go b/src/irc/server.go
index c7ea4107..8c9cdd31 100644
--- a/src/irc/server.go
+++ b/src/irc/server.go
@@ -7,24 +7,27 @@ import (
 )
 
 type Server struct {
-	ctime time.Time
-	name string
-	ch chan *ClientMessage
-	nicks map[string]*Client
+	hostname string
+	ctime    time.Time
+	name     string
+	recv     chan<- *ClientMessage
+	nicks    map[string]*Client
+	channels map[string]*Channel
 }
 
 type ClientMessage struct {
-	client *Client
+	client  *Client
 	message Message
 }
 
 func NewServer(name string) *Server {
-	server := new(Server)
-	server.ctime = time.Now()
-	server.name = name
-	server.ch = make(chan *ClientMessage)
-	server.nicks = make(map[string]*Client)
-	go server.Receive()
+	recv := make(chan *ClientMessage)
+	server := &Server{ctime: time.Now(), name: name, recv: recv, nicks: make(map[string]*Client), channels: make(map[string]*Channel)}
+	go func() {
+		for m := range recv {
+			m.message.Handle(server, m.client)
+		}
+	}()
 	return server
 }
 
@@ -34,18 +37,104 @@ func (s *Server) Listen(addr string) {
 		log.Fatal("Server.Listen: ", err)
 	}
 
+	s.hostname = LookupHostname(listener.Addr())
+	log.Print("Server.Listen: listening on ", addr)
+
 	for {
 		conn, err := listener.Accept()
 		if err != nil {
 			log.Print("Server.Listen: ", err)
 			continue
 		}
-		go NewClient(conn).Communicate(s.ch)
+		log.Print("Server.Listen: accepted ", conn.RemoteAddr())
+		go NewClient(conn).Communicate(s)
 	}
 }
 
-func (s *Server) Receive() {
-	for m := range s.ch {
-		m.message.Handle(s, m.client)
+func (s *Server) GetOrMakeChannel(name string) *Channel {
+	channel := s.channels[name]
+
+	if channel == nil {
+		channel = NewChannel(s, name)
+		s.channels[name] = channel
+	}
+
+	return channel
+}
+
+// Send a message to clients of channels fromClient is a member.
+func (s *Server) SendToInterestedClients(fromClient *Client, reply Reply) {
+	clients := make(map[*Client]bool)
+	for channel := range fromClient.channels {
+		for client := range channel.members {
+			clients[client] = true
+		}
+	}
+
+	for client := range clients {
+		client.send <- reply
 	}
 }
+
+// server functionality
+
+func (s *Server) ChangeNick(c *Client, newNick string) {
+	if s.nicks[newNick] != nil {
+		c.send <- ErrNickNameInUse(s, newNick)
+		return
+	}
+
+	s.SendToInterestedClients(c, RplNick(c, newNick))
+
+	if c.nick != "" {
+		delete(s.nicks, c.nick)
+	}
+	c.nick = newNick
+	s.nicks[c.nick] = c
+
+	s.TryRegister(c)
+}
+
+func (s *Server) Register(c *Client, user string, realName string) {
+	if c.username != "" {
+		c.send <- ErrAlreadyRegistered(s)
+		return
+	}
+
+	c.username, c.realname = user, realName
+	s.TryRegister(c)
+}
+
+func (s *Server) TryRegister(c *Client) {
+	if !c.registered && c.HasNick() && c.HasUser() {
+		c.registered = true
+		c.send <- RplWelcome(s, c)
+		c.send <- RplYourHost(s, c)
+		c.send <- RplCreated(s)
+		c.send <- RplMyInfo(s)
+	}
+}
+
+func (s *Server) Quit(c *Client, message string) {
+	for channel := range c.channels {
+		channel.Part(c, message)
+	}
+	delete(s.nicks, c.nick)
+
+	c.conn.Close()
+}
+
+func (s *Server) ChangeUserMode(c *Client, modes []string) {
+	for _, mode := range modes {
+		if mode == "+i" {
+			c.invisible = true
+		} else if mode == "-i" {
+			c.invisible = false
+		}
+	}
+	c.send <- RplUModeIs(s, c)
+}
+
+func (s *Server) Id() string {
+	return s.hostname
+}