Add support for WHOX

This adds support for WHOX, without bothering about flags and mask2
because Solanum and Ergo [1] don't support it either.

The motivation is to allow clients to reliably query account names.

It's not possible to use WHOX tokens to route replies to the right
client, because RPL_ENDOFWHO doesn't contain it.

[1]: https://github.com/ergochat/ergo/pull/1184

Closes: https://todo.sr.ht/~emersion/soju/135

downstream.go

@@ -236,6 +236,7 @@ var passthroughIsupport = map[string]bool{
 	"TOPICLEN":      true,
 	"USERLEN":       true,
 	"UTF8ONLY":      true,
+	"WHOX":          true,
 }
 
 type downstreamConn struct {
@@ -1157,6 +1158,10 @@ func (dc *downstreamConn) welcome() error {
 		isupport = append(isupport, fmt.Sprintf("BOUNCER_NETID=%v", dc.network.ID))
 	}
 
+	if dc.network == nil && dc.caps["soju.im/bouncer-networks"] {
+		isupport = append(isupport, "WHOX")
+	}
+
 	if uc := dc.upstream(); uc != nil {
 		for k := range passthroughIsupport {
 			v, ok := uc.isupport[k]
@@ -1882,6 +1887,10 @@ func (dc *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
 				})
 			}
 		}
+	// For WHOX docs, see:
+	// - http://faerion.sourceforge.net/doc/irc/whox.var
+	// - https://github.com/quakenet/snircd/blob/master/doc/readme.who
+	// Note, many features aren't widely implemented, such as flags and mask2
 	case "WHO":
 		if len(msg.Params) == 0 {
 			// TODO: support WHO without parameters
@@ -1893,52 +1902,80 @@ func (dc *downstreamConn) handleMessageRegistered(msg *irc.Message) error {
 			return nil
 		}
 
-		// TODO: support WHO masks
+		// Clients will use the first mask to match RPL_ENDOFWHO
-		entity := msg.Params[0]
+		endOfWhoToken := msg.Params[0]
-		entityCM := casemapASCII(entity)
 
-		if dc.network == nil && entityCM == dc.nickCM {
+		// TODO: add support for WHOX mask2
+		mask := msg.Params[0]
+		var options string
+		if len(msg.Params) > 1 {
+			options = msg.Params[1]
+		}
+
+		optionsParts := strings.SplitN(options, "%", 2)
+		// TODO: add support for WHOX flags in optionsParts[0]
+		var fields, whoxToken string
+		if len(optionsParts) == 2 {
+			optionsParts := strings.SplitN(optionsParts[1], ",", 2)
+			fields = strings.ToLower(optionsParts[0])
+			if len(optionsParts) == 2 && strings.Contains(fields, "t") {
+				whoxToken = optionsParts[1]
+			}
+		}
+
+		// TODO: support mixed bouncer/upstream WHO queries
+		maskCM := casemapASCII(mask)
+		if dc.network == nil && maskCM == dc.nickCM {
 			// TODO: support AWAY (H/G) in self WHO reply
 			flags := "H"
 			if dc.user.Admin {
 				flags += "*"
 			}
-			dc.SendMessage(&irc.Message{
+			info := whoxInfo{
-				Prefix:  dc.srv.prefix(),
+				Token:    whoxToken,
-				Command: irc.RPL_WHOREPLY,
+				Username: dc.user.Username,
-				Params:  []string{dc.nick, "*", dc.user.Username, dc.hostname, dc.srv.Hostname, dc.nick, flags, "0 " + dc.realname},
+				Hostname: dc.hostname,
-			})
+				Server:   dc.srv.Hostname,
+				Nickname: dc.nick,
+				Flags:    flags,
+				Realname: dc.realname,
+			}
+			dc.SendMessage(generateWHOXReply(dc.srv.prefix(), dc.nick, fields, &info))
 			dc.SendMessage(&irc.Message{
 				Prefix:  dc.srv.prefix(),
 				Command: irc.RPL_ENDOFWHO,
-				Params:  []string{dc.nick, dc.nick, "End of /WHO list"},
+				Params:  []string{dc.nick, endOfWhoToken, "End of /WHO list"},
 			})
 			return nil
 		}
-		if entityCM == serviceNickCM {
+		if maskCM == serviceNickCM {
-			dc.SendMessage(&irc.Message{
+			info := whoxInfo{
-				Prefix:  dc.srv.prefix(),
+				Token:    whoxToken,
-				Command: irc.RPL_WHOREPLY,
+				Username: servicePrefix.User,
-				Params:  []string{serviceNick, "*", servicePrefix.User, servicePrefix.Host, dc.srv.Hostname, serviceNick, "H*", "0 " + serviceRealname},
+				Hostname: servicePrefix.Host,
-			})
+				Server:   dc.srv.Hostname,
+				Nickname: serviceNick,
+				Flags:    "H*",
+				Realname: serviceRealname,
+			}
+			dc.SendMessage(generateWHOXReply(dc.srv.prefix(), dc.nick, fields, &info))
 			dc.SendMessage(&irc.Message{
 				Prefix:  dc.srv.prefix(),
 				Command: irc.RPL_ENDOFWHO,
-				Params:  []string{dc.nick, serviceNick, "End of /WHO list"},
+				Params:  []string{dc.nick, endOfWhoToken, "End of /WHO list"},
 			})
 			return nil
 		}
 
-		uc, upstreamName, err := dc.unmarshalEntity(entity)
+		// TODO: properly support WHO masks
+		uc, upstreamMask, err := dc.unmarshalEntity(mask)
 		if err != nil {
 			return err
 		}
 
-		var params []string
+		params := []string{upstreamMask}
-		if len(msg.Params) == 2 {
+		if options != "" {
-			params = []string{upstreamName, msg.Params[1]}
+			params = append(params, options)
-		} else {
-			params = []string{upstreamName}
 		}
 
 		uc.SendMessageLabeled(dc.id, &irc.Message{

irc.go

@@ -17,6 +17,7 @@ const (
 	rpl_globalusers   = "266"
 	rpl_creationtime  = "329"
 	rpl_topicwhotime  = "333"
+	rpl_whospcrpl     = "354"
 	err_invalidcapcmd = "410"
 )
 
@@ -682,3 +683,80 @@ func parseChatHistoryBound(param string) time.Time {
 		return time.Time{}
 	}
 }
+
+type whoxInfo struct {
+	Token    string
+	Username string
+	Hostname string
+	Server   string
+	Nickname string
+	Flags    string
+	Account  string
+	Realname string
+}
+
+func generateWHOXReply(prefix *irc.Prefix, nick, fields string, info *whoxInfo) *irc.Message {
+	if fields == "" {
+		return &irc.Message{
+			Prefix:  prefix,
+			Command: irc.RPL_WHOREPLY,
+			Params:  []string{nick, "*", info.Username, info.Hostname, info.Server, info.Nickname, info.Flags, "0 " + info.Realname},
+		}
+	}
+
+	fieldSet := make(map[byte]bool)
+	for i := 0; i < len(fields); i++ {
+		fieldSet[fields[i]] = true
+	}
+
+	var params []string
+	if fieldSet['t'] {
+		params = append(params, info.Token)
+	}
+	if fieldSet['c'] {
+		params = append(params, "*")
+	}
+	if fieldSet['u'] {
+		params = append(params, info.Username)
+	}
+	if fieldSet['i'] {
+		params = append(params, "255.255.255.255")
+	}
+	if fieldSet['h'] {
+		params = append(params, info.Hostname)
+	}
+	if fieldSet['s'] {
+		params = append(params, info.Server)
+	}
+	if fieldSet['n'] {
+		params = append(params, info.Nickname)
+	}
+	if fieldSet['f'] {
+		params = append(params, info.Flags)
+	}
+	if fieldSet['d'] {
+		params = append(params, "0")
+	}
+	if fieldSet['l'] { // idle time
+		params = append(params, "0")
+	}
+	if fieldSet['a'] {
+		account := "0" // WHOX uses "0" to mean "no account"
+		if info.Account != "" && info.Account != "*" {
+			account = info.Account
+		}
+		params = append(params, account)
+	}
+	if fieldSet['o'] {
+		params = append(params, "0")
+	}
+	if fieldSet['r'] {
+		params = append(params, info.Realname)
+	}
+
+	return &irc.Message{
+		Prefix:  prefix,
+		Command: rpl_whospcrpl,
+		Params:  append([]string{nick}, params...),
+	}
+}

upstream.go

@@ -1452,6 +1452,11 @@ func (uc *upstreamConn) handleMessage(msg *irc.Message) error {
 		// Ignore
 	case irc.RPL_YOURHOST, irc.RPL_CREATED:
 		// Ignore
+	case rpl_whospcrpl:
+		// Not supported in multi-upstream mode, forward as-is
+		uc.forEachDownstream(func(dc *downstreamConn) {
+			dc.SendMessage(msg)
+		})
 	case irc.RPL_LUSERCLIENT, irc.RPL_LUSEROP, irc.RPL_LUSERUNKNOWN, irc.RPL_LUSERCHANNELS, irc.RPL_LUSERME:
 		fallthrough
 	case irc.RPL_STATSVLINE, rpl_statsping, irc.RPL_STATSBLINE, irc.RPL_STATSDLINE: