diff --git a/const.go b/const.go
deleted file mode 100644
index 77b1c71..0000000
--- a/const.go
+++ /dev/null
@@ -1,177 +0,0 @@
-package main
-
-type command string
-
-type channelType int
-
-const (
-	REGULAR channelType = iota
-	LOCAL
-)
-
-// client commands
-const (
-	CAP          command = "CAP"
-	AUTHENTICATE command = "AUTHENTICATE"
-	PASS         command = "PASS"
-	NICK         command = "NICK"
-	USER         command = "USER"
-	OPER         command = "OPER"
-	QUIT         command = "QUIT"
-
-	JOIN   command = "JOIN"
-	PART   command = "PART"
-	TOPIC  command = "TOPIC"
-	NAMES  command = "NAMES"
-	LIST   command = "LIST"
-	INVITE command = "INVITE"
-	KICK   command = "KICK"
-
-	MOTD    command = "MOTD"
-	VERSION command = "VERSION"
-	ADMIN   command = "ADMIN"
-	CONNECT command = "CONNECT"
-	TIME    command = "TIME"
-	STATS   command = "STATS"
-	INFO    command = "INFO"
-	MODE    command = "MODE"
-
-	PRIVMSG command = "PRIVMSG"
-	NOTICE  command = "NOTICE"
-
-	KILL command = "KILL"
-
-	AWAY     command = "AWAY"
-	USERHOST command = "USERHOST"
-)
-
-// numerics
-const (
-	RPL_WELCOME  command = "001"
-	RPL_YOURHOST command = "002"
-	RPL_CREATED  command = "003"
-	RPL_MYINFO   command = "004"
-	RPL_ISUPPORT command = "005"
-
-	RPL_BOUNCE command = "010"
-
-	RPL_UMODEIS       command = "221"
-	RPL_LUSERCLIENT   command = "251"
-	RPL_LUSEROP       command = "252"
-	RPL_LUSERUNKNOWN  command = "253"
-	RPL_LUSERCHANNELS command = "254"
-	RPL_LUSERME       command = "255"
-	RPL_ADMINME       command = "256"
-	RPL_ADMINLOC1     command = "257"
-	RPL_ADMINLOC2     command = "258"
-	RPL_ADMINEMAIL    command = "259"
-
-	RPL_TRYAGAIN command = "263"
-
-	RPL_LOCALUSERS  command = "265"
-	RPL_GLOBALUSERS command = "266"
-
-	RPL_WHOISCERTFP command = "276"
-
-	RPL_NONE command = "300"
-
-	RPL_AWAY     command = "301"
-	RPL_USERHOST command = "302"
-	RPL_ISON     command = "303"
-	RPL_UNAWAY   command = "305"
-	RPL_NOWAWAY  command = "306"
-
-	RPL_WHOISUSER     command = "311"
-	RPL_WHOISSERVER   command = "312"
-	RPL_WHOISOPERATOR command = "313"
-	RPL_WHOWASUSER    command = "314"
-	RPL_WHOISIDLE     command = "317"
-	RPL_ENDOFWHOIS    command = "318"
-	RPL_WHOISCHANNELS command = "319"
-
-	RPL_LISTSTART command = "321"
-	RPL_LIST      command = "322"
-	RPL_LISTEND   command = "323"
-
-	RPL_CHANNELMODEIS command = "324"
-	RPL_CREATIONTIME  command = "329"
-	RPL_NOTOPIC       command = "331"
-	RPL_TOPIC         command = "332"
-	RPL_TOPICWHOTIME  command = "333"
-
-	RPL_INVITING        command = "341"
-	RPL_INVITELIST      command = "346"
-	RPL_ENDOFINVITELIST command = "347"
-	RPL_EXCEPTLIST      command = "348"
-	RPL_ENDOFEXCEPTLIST command = "349"
-
-	RPL_VERSION command = "351"
-
-	RPL_NAMREPLY     command = "353"
-	RPL_ENDOFNAMES   command = "366"
-	RPL_BANLIST      command = "367"
-	RPL_ENDOFBANLIST command = "368"
-	RPL_ENDOFWHOWAS  command = "369"
-
-	RPL_MOTD      command = "372"
-	RPL_MOTDSTART command = "375"
-	RPL_ENDOFMOTD command = "376" // see also ERR_NOMOTD
-
-	RPL_YOUREOPER command = "381"
-
-	RPL_REHASHING command = "382"
-
-	ERR_UNKNOWNERROR     command = "400"
-	ERR_NOSUCHNICK       command = "401"
-	ERR_NOSUCHSERVER     command = "402"
-	ERR_NOSUCHCHANNEL    command = "403"
-	ERR_CANNOTSENDTOCHAN command = "404"
-	ERR_TOOMANYCHANNELS  command = "405"
-
-	ERR_UNKNOWNCOMMAND command = "421"
-
-	ERR_NOMOTD command = "422"
-
-	ERR_ERRONEUSNICKNAME command = "432"
-	ERR_NICKNAMEINUSE    command = "433"
-
-	ERR_USERNOTINCHANNEL command = "441"
-	ERR_NOTONCHANNEL     command = "442"
-	ERR_USERONCHANNEL    command = "443"
-
-	ERR_NOTREGISTERED command = "451"
-
-	ERR_NEEDMOREPARAMS    command = "461"
-	ERR_ALREADYREGISTERED command = "462"
-	ERR_PASSWDMISMATCH    command = "464"
-	ERR_YOUREBANNEDCREEP  command = "465"
-	ERR_CHANNELISFULL     command = "471"
-	ERR_UNKNOWNMODE       command = "472"
-	ERR_INVITEONLYCHAN    command = "473"
-	ERR_BANNEDFROMCHAN    command = "474"
-	ERR_BADCHANNELKEY     command = "475"
-	ERR_BADCHANMASK       command = "476"
-
-	ERR_NOPRIVILEGES     command = "481"
-	ERR_CHANOPRIVSNEEDED command = "482"
-	ERR_CANTKILLSERVER   command = "483"
-	ERR_NOOPERHOST       command = "491"
-
-	ERR_UMODEUNKNOWNFLAG command = "501"
-	ERR_USERSDONTMATCH   command = "502"
-
-	RPL_STARTTLS command = "670"
-	ERR_STARTTLS command = "691"
-
-	ERR_NOPRIVS command = "723"
-
-	RPL_LOGGEDIN    command = "900"
-	RPL_LOGGEDOUT   command = "901"
-	ERR_NICKLOCKED  command = "902"
-	RPL_SASLSUCCESS command = "903"
-	ERR_SASLFAIL    command = "904"
-	ERR_SASLTOOLONG command = "905"
-	ERR_SASLABORTED command = "906"
-	ERR_SASLALREADY command = "907"
-	RPL_SASLMECHS   command = "908"
-)
diff --git a/message/const.go b/message/const.go
new file mode 100644
index 0000000..788d543
--- /dev/null
+++ b/message/const.go
@@ -0,0 +1,170 @@
+package message
+
+type Command string
+
+// client commands
+const (
+	CAP          Command = "CAP"
+	AUTHENTICATE Command = "AUTHENTICATE"
+	PASS         Command = "PASS"
+	NICK         Command = "NICK"
+	USER         Command = "USER"
+	OPER         Command = "OPER"
+	QUIT         Command = "QUIT"
+
+	JOIN   Command = "JOIN"
+	PART   Command = "PART"
+	TOPIC  Command = "TOPIC"
+	NAMES  Command = "NAMES"
+	LIST   Command = "LIST"
+	INVITE Command = "INVITE"
+	KICK   Command = "KICK"
+
+	MOTD    Command = "MOTD"
+	VERSION Command = "VERSION"
+	ADMIN   Command = "ADMIN"
+	CONNECT Command = "CONNECT"
+	TIME    Command = "TIME"
+	STATS   Command = "STATS"
+	INFO    Command = "INFO"
+	MODE    Command = "MODE"
+
+	PRIVMSG Command = "PRIVMSG"
+	NOTICE  Command = "NOTICE"
+
+	KILL Command = "KILL"
+
+	AWAY     Command = "AWAY"
+	USERHOST Command = "USERHOST"
+)
+
+// numerics
+const (
+	RPL_WELCOME  Command = "001"
+	RPL_YOURHOST Command = "002"
+	RPL_CREATED  Command = "003"
+	RPL_MYINFO   Command = "004"
+	RPL_ISUPPORT Command = "005"
+
+	RPL_BOUNCE Command = "010"
+
+	RPL_UMODEIS       Command = "221"
+	RPL_LUSERCLIENT   Command = "251"
+	RPL_LUSEROP       Command = "252"
+	RPL_LUSERUNKNOWN  Command = "253"
+	RPL_LUSERCHANNELS Command = "254"
+	RPL_LUSERME       Command = "255"
+	RPL_ADMINME       Command = "256"
+	RPL_ADMINLOC1     Command = "257"
+	RPL_ADMINLOC2     Command = "258"
+	RPL_ADMINEMAIL    Command = "259"
+
+	RPL_TRYAGAIN Command = "263"
+
+	RPL_LOCALUSERS  Command = "265"
+	RPL_GLOBALUSERS Command = "266"
+
+	RPL_WHOISCERTFP Command = "276"
+
+	RPL_NONE Command = "300"
+
+	RPL_AWAY     Command = "301"
+	RPL_USERHOST Command = "302"
+	RPL_ISON     Command = "303"
+	RPL_UNAWAY   Command = "305"
+	RPL_NOWAWAY  Command = "306"
+
+	RPL_WHOISUSER     Command = "311"
+	RPL_WHOISSERVER   Command = "312"
+	RPL_WHOISOPERATOR Command = "313"
+	RPL_WHOWASUSER    Command = "314"
+	RPL_WHOISIDLE     Command = "317"
+	RPL_ENDOFWHOIS    Command = "318"
+	RPL_WHOISCHANNELS Command = "319"
+
+	RPL_LISTSTART Command = "321"
+	RPL_LIST      Command = "322"
+	RPL_LISTEND   Command = "323"
+
+	RPL_CHANNELMODEIS Command = "324"
+	RPL_CREATIONTIME  Command = "329"
+	RPL_NOTOPIC       Command = "331"
+	RPL_TOPIC         Command = "332"
+	RPL_TOPICWHOTIME  Command = "333"
+
+	RPL_INVITING        Command = "341"
+	RPL_INVITELIST      Command = "346"
+	RPL_ENDOFINVITELIST Command = "347"
+	RPL_EXCEPTLIST      Command = "348"
+	RPL_ENDOFEXCEPTLIST Command = "349"
+
+	RPL_VERSION Command = "351"
+
+	RPL_NAMREPLY     Command = "353"
+	RPL_ENDOFNAMES   Command = "366"
+	RPL_BANLIST      Command = "367"
+	RPL_ENDOFBANLIST Command = "368"
+	RPL_ENDOFWHOWAS  Command = "369"
+
+	RPL_MOTD      Command = "372"
+	RPL_MOTDSTART Command = "375"
+	RPL_ENDOFMOTD Command = "376" // see also ERR_NOMOTD
+
+	RPL_YOUREOPER Command = "381"
+
+	RPL_REHASHING Command = "382"
+
+	ERR_UNKNOWNERROR     Command = "400"
+	ERR_NOSUCHNICK       Command = "401"
+	ERR_NOSUCHSERVER     Command = "402"
+	ERR_NOSUCHCHANNEL    Command = "403"
+	ERR_CANNOTSENDTOCHAN Command = "404"
+	ERR_TOOMANYCHANNELS  Command = "405"
+
+	ERR_UNKNOWNCOMMAND Command = "421"
+
+	ERR_NOMOTD Command = "422"
+
+	ERR_ERRONEUSNICKNAME Command = "432"
+	ERR_NICKNAMEINUSE    Command = "433"
+
+	ERR_USERNOTINCHANNEL Command = "441"
+	ERR_NOTONCHANNEL     Command = "442"
+	ERR_USERONCHANNEL    Command = "443"
+
+	ERR_NOTREGISTERED Command = "451"
+
+	ERR_NEEDMOREPARAMS    Command = "461"
+	ERR_ALREADYREGISTERED Command = "462"
+	ERR_PASSWDMISMATCH    Command = "464"
+	ERR_YOUREBANNEDCREEP  Command = "465"
+	ERR_CHANNELISFULL     Command = "471"
+	ERR_UNKNOWNMODE       Command = "472"
+	ERR_INVITEONLYCHAN    Command = "473"
+	ERR_BANNEDFROMCHAN    Command = "474"
+	ERR_BADCHANNELKEY     Command = "475"
+	ERR_BADCHANMASK       Command = "476"
+
+	ERR_NOPRIVILEGES     Command = "481"
+	ERR_CHANOPRIVSNEEDED Command = "482"
+	ERR_CANTKILLSERVER   Command = "483"
+	ERR_NOOPERHOST       Command = "491"
+
+	ERR_UMODEUNKNOWNFLAG Command = "501"
+	ERR_USERSDONTMATCH   Command = "502"
+
+	RPL_STARTTLS Command = "670"
+	ERR_STARTTLS Command = "691"
+
+	ERR_NOPRIVS Command = "723"
+
+	RPL_LOGGEDIN    Command = "900"
+	RPL_LOGGEDOUT   Command = "901"
+	ERR_NICKLOCKED  Command = "902"
+	RPL_SASLSUCCESS Command = "903"
+	ERR_SASLFAIL    Command = "904"
+	ERR_SASLTOOLONG Command = "905"
+	ERR_SASLABORTED Command = "906"
+	ERR_SASLALREADY Command = "907"
+	RPL_SASLMECHS   Command = "908"
+)
diff --git a/message/message.go b/message/message.go
new file mode 100644
index 0000000..2b29e4f
--- /dev/null
+++ b/message/message.go
@@ -0,0 +1,273 @@
+package message
+
+import (
+	"bytes"
+	"strings"
+)
+
+type Tag struct {
+	Key   string
+	Value string
+}
+
+// Tags is an key-order-preserving, last-insert-wins "set" of Tag{}s
+type Tags struct {
+	kv   map[string]int // quick lookups for inserts
+	tags []Tag
+}
+
+// Insert adds the given tag to the set, overriding any existing tag with that Key
+func (t *Tags) Insert(new Tag) {
+	if t.kv == nil {
+		t.kv = map[string]int{}
+	}
+	i, ok := t.kv[new.Key]
+	if ok {
+		t.tags[i] = new
+	} else {
+		t.kv[new.Key] = len(t.tags)
+		t.tags = append(t.tags, new)
+	}
+}
+
+// GetSlice returns a simple slice of tags from the set
+func (t *Tags) GetSlice() []Tag {
+	return t.tags
+}
+
+// A Message represents a parsed set of Tags/Source/Command/Parameters from a Raw string.
+//
+// Tags/Source/Command/Parameters are all set from the Raw after ParseMessage() is called.
+// Calling ParseMessage multiple times (without changing Raw) should be a no-op.
+//
+// Canonicalize() returns Tags/Source/Command/Parameters transformed back into an RFC-compliant []byte.
+//
+// Reusing a message struct to parse multiple Raw messages is possible, but frowned upon.
+//
+// Tag values are automatically escaped during parsing.
+type Message struct {
+	Tags       []Tag    // An ordered slice of Key=Value pairs
+	Source     string   // An optional string denoting the source of the message
+	Command    Command  // A command/numeric for the message
+	Parameters []string // Zero or more parameters for the Command.
+	Raw        string
+
+	parseIndex int
+}
+
+// ParseMessage will attempt to parse whatever it's given as an IRC Message,
+// and populate Tags/Source/Command/Parameters with the results.
+// Garbage in, garbage out, though. The parser tries its best, but doesn't aggressively
+// validate messages.
+//
+// Tag values are automatically escaped during parsing, as needed.
+func (m *Message) ParseMessage() {
+	m.parseIndex = 0
+	m.consumeSpaces()
+	if m.consume('@') {
+		m.Tags = m.parseTags()
+	}
+	m.consumeSpaces()
+	if m.consume(':') {
+		m.Source = m.parseSource()
+	}
+	m.consumeSpaces()
+	m.Command = m.parseCommand()
+	m.consumeSpaces()
+	m.Parameters = m.parseParameters()
+}
+
+func (m *Message) parseTags() []Tag {
+	tags := &Tags{}
+	for {
+		next := m.findNext("=", ";")
+		if next == -1 {
+			break
+		} else if m.Raw[m.parseIndex+next] == '=' {
+			key := m.Raw[m.parseIndex : m.parseIndex+next]
+			m.parseIndex += next + 1
+			eot := m.findNext(";", " ")
+			if eot == -1 { // ran out of message, probably
+				tags.Insert(Tag{Key: key, Value: unescapeTag(m.Raw[m.parseIndex:])})
+				m.parseIndex = len(m.Raw)
+				break
+			}
+			tags.Insert(Tag{Key: key, Value: unescapeTag(m.Raw[m.parseIndex : m.parseIndex+eot])})
+			m.parseIndex += len(m.Raw[m.parseIndex:m.parseIndex+eot]) + 1
+		} else if m.Raw[m.parseIndex+next] == ';' {
+			key := m.Raw[m.parseIndex : m.parseIndex+next]
+			m.parseIndex += next + 1
+			tags.Insert(Tag{Key: key, Value: ""})
+		}
+	}
+	return tags.GetSlice()
+}
+
+func (m *Message) parseSource() string {
+	start := m.parseIndex
+	endofparse := strings.Index(m.Raw[m.parseIndex:], " ")
+	if endofparse == -1 {
+		m.parseIndex = len(m.Raw) // out of message! which is weird.
+	} else {
+		m.parseIndex += endofparse
+	}
+	return m.Raw[start:m.parseIndex]
+}
+
+func (m *Message) parseCommand() Command {
+	start := m.parseIndex
+	endofparse := strings.Index(m.Raw[m.parseIndex:], " ")
+	if endofparse == -1 {
+		m.parseIndex = len(m.Raw) // a command with no parameters
+	} else {
+		m.parseIndex += endofparse
+	}
+	return Command(m.Raw[start:m.parseIndex])
+}
+
+func (m *Message) parseParameters() []string {
+	params := []string{}
+	for m.parseIndex <= len(m.Raw) {
+		m.consumeSpaces()
+		if m.consume(':') { // "run until end of line"
+			params = append(params, m.Raw[m.parseIndex:])
+			break
+		}
+		endofparse := strings.Index(m.Raw[m.parseIndex:], " ")
+		if endofparse == -1 { // no further params
+			break
+		}
+		params = append(params, m.Raw[m.parseIndex:m.parseIndex+endofparse])
+		m.parseIndex += endofparse
+	}
+	return params
+}
+
+func (m *Message) consumeSpaces() {
+	if len(m.Raw) <= m.parseIndex {
+		return
+	}
+	for len(m.Raw) > m.parseIndex && m.Raw[m.parseIndex] == ' ' {
+		m.parseIndex++
+	}
+}
+
+func (m *Message) consume(r byte) bool {
+	if len(m.Raw) <= m.parseIndex {
+		return false
+	}
+	if m.Raw[m.parseIndex] == r {
+		m.parseIndex++
+		return true
+	}
+	return false
+}
+
+func (m *Message) findNext(bs ...string) int {
+	r := -1
+	for _, b := range bs {
+		i := strings.Index(m.Raw[m.parseIndex:], b)
+		if r == -1 || (i != -1 && i < r) {
+			r = i
+		}
+	}
+	return r
+}
+
+func unescapeTag(s string) string {
+	sb := strings.Builder{}
+	escaping := false
+	i := 0
+	for i < len(s) {
+		if escaping {
+			switch s[i] {
+			case ':':
+				sb.WriteByte(';')
+			case '\\':
+				sb.WriteByte('\\')
+			case 's':
+				sb.WriteByte(' ')
+			case 'r':
+				sb.WriteByte('\r')
+			case 'n':
+				sb.WriteByte('\n')
+			default:
+				sb.WriteByte(s[i])
+			}
+			i++
+			escaping = false
+		} else if s[i] == '\\' {
+			if !escaping {
+				escaping = true
+				i++
+				continue
+			}
+		} else {
+			sb.WriteByte(s[i])
+			i++
+		}
+	}
+	return sb.String()
+}
+
+func escapeTag(s string) string {
+	sb := strings.Builder{}
+	for i := range s {
+		switch s[i] {
+		case ';':
+			sb.Write([]byte{'\\', ':'})
+		case ' ':
+			sb.Write([]byte{'\\', 's'})
+		case '\\':
+			sb.Write([]byte{'\\', '\\'})
+		case '\n':
+			sb.Write([]byte{'\\', 'n'})
+		case '\r':
+			sb.Write([]byte{'\\', 'r'})
+		default:
+			sb.WriteByte(s[i])
+		}
+	}
+	return sb.String()
+}
+
+func (m *Message) Canonicalize() []byte {
+	sb := bytes.NewBuffer([]byte{})
+	if m.Tags != nil && len(m.Tags) > 0 {
+		sb.WriteByte('@')
+		for i := range m.Tags {
+			sb.WriteString(m.Tags[i].Key)
+			if m.Tags[i].Value != "" {
+				sb.WriteByte('=')
+				sb.WriteString(escapeTag(m.Tags[i].Value))
+			}
+			if i+1 != len(m.Tags) {
+				sb.WriteByte(';')
+			}
+		}
+		sb.WriteByte(' ')
+	}
+
+	if m.Source != "" {
+		sb.WriteByte(':')
+		sb.WriteString(m.Source)
+		sb.WriteByte(' ')
+	}
+
+	sb.WriteString(string(m.Command))
+
+	if m.Parameters != nil && len(m.Parameters) > 0 {
+		sb.WriteByte(' ')
+		for i := range m.Parameters {
+			if i+1 == len(m.Parameters) && (strings.Contains(m.Parameters[i], " ") || m.Parameters[i] == "" || m.Parameters[i][0] == ':') {
+				sb.WriteByte(':')
+			}
+			sb.WriteString(m.Parameters[i])
+			if i+1 != len(m.Parameters) {
+				sb.WriteByte(' ')
+			}
+		}
+	}
+
+	return sb.Bytes()
+}
diff --git a/message/message_test.go b/message/message_test.go
new file mode 100644
index 0000000..625e087
--- /dev/null
+++ b/message/message_test.go
@@ -0,0 +1,358 @@
+package message
+
+import "testing"
+
+func TestParsing(t *testing.T) {
+	testcases := []struct {
+		input  string
+		output *Message
+	}{
+		// these inputs are based on
+		// https://github.com/ircdocs/parser-tests/blob/master/tests/msg-split.yaml
+		// and https://modern.ircdocs.horse/#messages
+		{
+			input: `:irc.example.com CAP LS * :multi-prefix extended-join sasl`,
+			output: &Message{
+				Source:     "irc.example.com",
+				Command:    CAP,
+				Parameters: []string{"LS", "*", "multi-prefix extended-join sasl"},
+			}},
+		{
+			input: `@id=234AB :dan!d@localhost PRIVMSG #chan :Hey what's up!`,
+			output: &Message{
+				Tags:       []Tag{{"id", "234AB"}},
+				Source:     "dan!d@localhost",
+				Command:    PRIVMSG,
+				Parameters: []string{"#chan", "Hey what's up!"},
+			}},
+		{
+			input: `@a=b;c=32;k;rt=ql7 :dan!d@localhost PRIVMSG #chan :Hey what's up!`,
+			output: &Message{
+				Tags:       []Tag{{"a", "b"}, {"c", "32"}, {"k", ""}, {"rt", "ql7"}},
+				Source:     "dan!d@localhost",
+				Command:    PRIVMSG,
+				Parameters: []string{"#chan", "Hey what's up!"},
+			}},
+		{
+			input: `@a=b\\and\nk;c=72\s45;d=gh\:764 CAP`,
+			output: &Message{
+				Tags:    []Tag{{"a", "b\\and\nk"}, {"c", "72 45"}, {"d", `gh;764`}},
+				Command: CAP,
+			}},
+		{
+			input: `@tag1=value1;tag2;vendor1/tag3=value2;vendor2/tag4= :dan!d@localhost PRIVMSG #chan :Hey what's up!`,
+			output: &Message{
+				Tags:       []Tag{{"tag1", "value1"}, {"tag2", ""}, {"vendor1/tag3", "value2"}, {"vendor2/tag4", ""}},
+				Source:     "dan!d@localhost",
+				Command:    PRIVMSG,
+				Parameters: []string{"#chan", "Hey what's up!"},
+			}},
+		{
+			input: ":src AWAY",
+			output: &Message{
+				Source:  "src",
+				Command: AWAY,
+			}},
+		{
+			input: ":src AWAY ",
+			output: &Message{
+				Source:  "src",
+				Command: AWAY,
+			}},
+		{
+			input: `CAP REQ :sasl`,
+			output: &Message{
+				Command:    CAP,
+				Parameters: []string{"REQ", "sasl"},
+			}},
+		{
+			input: `CAP REQ :`,
+			output: &Message{
+				Command:    CAP,
+				Parameters: []string{"REQ", ""},
+			}},
+		{
+			input: `CAP REQ ::asdf`,
+			output: &Message{
+				Command:    CAP,
+				Parameters: []string{"REQ", ":asdf"},
+			}},
+		{
+			input: `CAP REQ :    asdf qwer`,
+			output: &Message{
+				Command:    CAP,
+				Parameters: []string{"REQ", "    asdf qwer"},
+			}},
+		{
+			input: ":coolguy!ag@net\x035w\x03ork.admin PRIVMSG foo :bar baz",
+			output: &Message{
+				Source:     "coolguy!ag@net\x035w\x03ork.admin",
+				Command:    PRIVMSG,
+				Parameters: []string{"foo", "bar baz"},
+			}},
+		{
+			input: `:coolguy PRIVMSG bar :lol :) `,
+			output: &Message{
+				Source:     "coolguy",
+				Command:    PRIVMSG,
+				Parameters: []string{"bar", "lol :) "},
+			}},
+		{
+			input: `:gravel.mozilla.org 432  #momo :Erroneous Nickname: Illegal characters`,
+			output: &Message{
+				Source:     "gravel.mozilla.org",
+				Command:    ERR_ERRONEUSNICKNAME,
+				Parameters: []string{"#momo", "Erroneous Nickname: Illegal characters"},
+			}},
+		{
+			input: `:gravel.mozilla.org MODE #tckk +n `,
+			output: &Message{
+				Source:     "gravel.mozilla.org",
+				Command:    MODE,
+				Parameters: []string{"#tckk", "+n"},
+			}},
+		{
+			input: ":services.esper.net MODE #foo-bar +o foobar  ",
+			output: &Message{
+				Source:     "services.esper.net",
+				Command:    MODE,
+				Parameters: []string{"#foo-bar", "+o", "foobar"},
+			}},
+		{
+			input: `@tag1=value\\ntest COMMAND`,
+			output: &Message{
+				Tags:    []Tag{{"tag1", `value\ntest`}},
+				Command: Command("COMMAND"),
+			}},
+		{
+			input: `@tag1=value\1 COMMAND`,
+			output: &Message{
+				Tags:    []Tag{{"tag1", `value1`}},
+				Command: Command("COMMAND"),
+			}},
+		{
+			input: `@tag1=value\ COMMAND`,
+			output: &Message{
+				Tags:    []Tag{{"tag1", `value`}},
+				Command: Command("COMMAND"),
+			}},
+		{
+			input: `@tag1=va\r\nlue COMMAND`,
+			output: &Message{
+				Tags:    []Tag{{"tag1", "va\r\nlue"}},
+				Command: Command("COMMAND"),
+			}},
+		{
+			input: `@tag1=1;tag2=3;tag3=4;tag1=5 COMMAND`,
+			output: &Message{
+				Tags:    []Tag{{"tag1", "5"}, {"tag2", "3"}, {"tag3", "4"}},
+				Command: Command("COMMAND"),
+			}},
+		{
+			input: `@tag1=1;tag2=3;tag3=4;tag1=5;vendor/tag2=8 COMMAND`,
+			output: &Message{
+				Tags:    []Tag{{"tag1", "5"}, {"tag2", "3"}, {"tag3", "4"}, {"vendor/tag2", "8"}},
+				Command: Command("COMMAND"),
+			}},
+		{
+			input: `:SomeOp MODE #channel :+i`,
+			output: &Message{
+				Source:     "SomeOp",
+				Command:    MODE,
+				Parameters: []string{"#channel", "+i"},
+			}},
+		{
+			input: `:SomeOp MODE #channel +oo SomeUser :AnotherUser`,
+			output: &Message{
+				Source:     "SomeOp",
+				Command:    MODE,
+				Parameters: []string{"#channel", "+oo", "SomeUser", "AnotherUser"},
+			}},
+		{
+			input: `:uttergarbage`,
+			output: &Message{
+				Source: "uttergarbage",
+			},
+		},
+		{
+			input: `@only=tags`,
+			output: &Message{
+				Tags: []Tag{{"only", "tags"}},
+			},
+		},
+		{
+			input: `@only=`,
+			output: &Message{
+				Tags: []Tag{{"only", ""}},
+			},
+		},
+	}
+	for _, tc := range testcases {
+		m := &Message{Raw: tc.input}
+		m.ParseMessage()
+		if len(tc.output.Tags) != len(m.Tags) {
+			t.Logf("tags: actual: %v, expected: %v", m.Tags, tc.output.Tags)
+			t.Fail()
+		}
+		for i := range tc.output.Tags {
+			if tc.output.Tags[i] != m.Tags[i] {
+				t.Logf("tags: actual: %+v, expected: %+v", m.Tags[i], tc.output.Tags[i])
+				t.Fail()
+			}
+		}
+		if tc.output.Source != m.Source {
+			t.Logf("source: actual: %v, expected: %v", m.Source, tc.output.Source)
+			t.Fail()
+		}
+		if tc.output.Command != m.Command {
+			t.Logf("command: actual: %v, expected: %v", m.Command, tc.output.Command)
+			t.Fail()
+		}
+		if len(tc.output.Parameters) != len(m.Parameters) {
+			t.Logf("parameters: actual: %v (%d), expected: %v (%d)", m.Parameters, len(m.Parameters), tc.output.Parameters, len(tc.output.Parameters))
+			t.Fail()
+		}
+		for i := range tc.output.Parameters {
+			if tc.output.Parameters[i] != m.Parameters[i] {
+				t.Logf("parameters: actual: %v, expected: %v", m.Parameters[i], tc.output.Parameters[i])
+				t.Fail()
+			}
+		}
+	}
+}
+
+func TestCanonicalization(t *testing.T) {
+	testcases := []struct {
+		input  *Message
+		output string
+	}{
+		// these outputs are based on
+		// https://github.com/ircdocs/parser-tests/blob/master/tests/msg-split.yaml
+		// and https://modern.ircdocs.horse/#messages
+		{
+			input: &Message{
+				Source:     "irc.example.com",
+				Command:    CAP,
+				Parameters: []string{"LS", "*", "multi-prefix extended-join sasl"},
+			},
+			output: `:irc.example.com CAP LS * :multi-prefix extended-join sasl`,
+		},
+		{
+			input: &Message{
+				Tags:       []Tag{{"id", "234AB"}},
+				Source:     "dan!d@localhost",
+				Command:    PRIVMSG,
+				Parameters: []string{"#chan", "Hey what's up!"},
+			},
+			output: `@id=234AB :dan!d@localhost PRIVMSG #chan :Hey what's up!`,
+		},
+		{
+			input: &Message{
+				Tags:       []Tag{{"a", "b"}, {"c", "32"}, {"k", ""}, {"rt", "ql7"}},
+				Source:     "dan!d@localhost",
+				Command:    PRIVMSG,
+				Parameters: []string{"#chan", "Hey what's up!"},
+			},
+			output: `@a=b;c=32;k;rt=ql7 :dan!d@localhost PRIVMSG #chan :Hey what's up!`,
+		},
+		{
+			input: &Message{
+				Tags:    []Tag{{"a", "b\\and\nk"}, {"c", "72 45"}, {"d", `gh;764`}},
+				Command: CAP,
+			},
+			output: `@a=b\\and\nk;c=72\s45;d=gh\:764 CAP`,
+		},
+		{
+			input: &Message{
+				Tags:       []Tag{{"tag1", "value1"}, {"tag2", ""}, {"vendor1/tag3", "value2"}, {"vendor2/tag4", ""}},
+				Source:     "dan!d@localhost",
+				Command:    PRIVMSG,
+				Parameters: []string{"#chan", "Hey what's up!"},
+			},
+			output: `@tag1=value1;tag2;vendor1/tag3=value2;vendor2/tag4 :dan!d@localhost PRIVMSG #chan :Hey what's up!`,
+		},
+		{
+			input: &Message{
+				Source:  "src",
+				Command: AWAY,
+			},
+			output: ":src AWAY",
+		},
+		{
+			input: &Message{
+				Command:    CAP,
+				Parameters: []string{"REQ", "sasl"},
+			},
+			output: `CAP REQ sasl`,
+		},
+		{
+			input: &Message{
+				Command:    CAP,
+				Parameters: []string{"REQ", ""},
+			},
+			output: `CAP REQ :`,
+		},
+		{
+			input: &Message{
+				Command:    CAP,
+				Parameters: []string{"REQ", ":asdf"},
+			},
+			output: `CAP REQ ::asdf`,
+		},
+		{
+			input: &Message{
+				Command:    CAP,
+				Parameters: []string{"REQ", "    asdf qwer"},
+			},
+			output: `CAP REQ :    asdf qwer`,
+		},
+		{
+			input: &Message{
+				Source:     "coolguy",
+				Command:    PRIVMSG,
+				Parameters: []string{"bar", "lol :) "},
+			},
+			output: `:coolguy PRIVMSG bar :lol :) `,
+		},
+		{
+			input: &Message{
+				Source:     "coolguy!ag@net\x035w\x03ork.admin",
+				Command:    PRIVMSG,
+				Parameters: []string{"foo", "bar baz"},
+			},
+			output: ":coolguy!ag@net\x035w\x03ork.admin PRIVMSG foo :bar baz",
+		},
+		{
+			input: &Message{
+				Tags:    []Tag{{"tag1", `value\ntest`}},
+				Command: Command("COMMAND"),
+			},
+			output: `@tag1=value\\ntest COMMAND`,
+		},
+		{
+			input: &Message{
+				Tags:    []Tag{{"tag1", "va\r\nlue"}},
+				Command: Command("COMMAND"),
+			},
+			output: `@tag1=va\r\nlue COMMAND`,
+		},
+	}
+	for _, tc := range testcases {
+		output := string(tc.input.Canonicalize())
+		if output != tc.output {
+			t.Logf("received '%s', expected '%s'", output, tc.output)
+			t.Fail()
+		}
+	}
+}
+
+func TestRoundTrip(t *testing.T) {
+	in := `@a=b;c=3\n2;k;rt=ql7 :dan!d@localhost PRIVMSG #chan :Hey what's up! `
+	m := &Message{Raw: in}
+	m.ParseMessage()
+	out := m.Canonicalize()
+	if string(out) != in {
+		t.Logf("expected '%s', received '%s'", in, string(out))
+		t.Fail()
+	}
+}