Add support for draft/account-registration proxying

This adds support for the draft/account-registration extension [1].
This allows downstreams to register on upstream networks.

[1]: https://ircv3.net/specs/extensions/account-registration

downstream.go

@@ -1079,6 +1079,21 @@ func (dc *downstreamConn) updateSupportedCaps() {
 		dc.unsetSupportedCap("sasl")
 	}
 
+	if uc := dc.upstream(); uc != nil && uc.caps["draft/account-registration"] {
+		// Strip "before-connect", because we require downstreams to be fully
+		// connected before attempting account registration.
+		values := strings.Split(uc.supportedCaps["draft/account-registration"], ",")
+		for i, v := range values {
+			if v == "before-connect" {
+				values = append(values[:i], values[i+1:]...)
+				break
+			}
+		}
+		dc.setSupportedCap("draft/account-registration", strings.Join(values, ","))
+	} else {
+		dc.unsetSupportedCap("draft/account-registration")
+	}
+
 	if _, ok := dc.user.msgStore.(chatHistoryMessageStore); ok && dc.network != nil {
 		dc.setSupportedCap("draft/event-playback", "")
 	} else {
@@ -2408,7 +2423,6 @@ func (dc *downstreamConn) handleMessageRegistered(ctx context.Context, msg *irc.
 		uc := dc.upstream()
 		if uc == nil || !uc.caps["sasl"] {
 			return ircError{&irc.Message{
-				Prefix:  dc.srv.prefix(),
 				Command: irc.ERR_SASLFAIL,
 				Params:  []string{dc.nick, "Upstream network authentication not supported"},
 			}}
@@ -2436,6 +2450,23 @@ func (dc *downstreamConn) handleMessageRegistered(ctx context.Context, msg *irc.
 				Params:  []string{"PLAIN"},
 			})
 		}
+	case "REGISTER", "VERIFY":
+		// Check number of params here, since we'll use that to save the
+		// credentials on command success
+		if (msg.Command == "REGISTER" && len(msg.Params) < 3) || (msg.Command == "VERIFY" && len(msg.Params) < 2) {
+			return newNeedMoreParamsError(msg.Command)
+		}
+
+		uc := dc.upstream()
+		if uc == nil || !uc.caps["draft/account-registration"] {
+			return ircError{&irc.Message{
+				Command: "FAIL",
+				Params:  []string{msg.Command, "TEMPORARILY_UNAVAILABLE", "*", "Upstream network account registration not supported"},
+			}}
+		}
+
+		uc.logger.Printf("starting %v with account name %v", msg.Command, msg.Params[0])
+		uc.enqueueCommand(dc, msg)
 	case "MONITOR":
 		// MONITOR is unsupported in multi-upstream mode
 		uc := dc.upstream()

upstream.go

@@ -35,6 +35,7 @@ var permanentUpstreamCaps = map[string]bool{
 	"server-time":      true,
 	"setname":          true,
 
+	"draft/account-registration": true,
 	"draft/extended-monitor":     true,
 }
 
@@ -300,6 +301,12 @@ func (uc *upstreamConn) endPendingCommands() {
 					Command: irc.ERR_SASLABORTED,
 					Params:  []string{dc.nick, "SASL authentication aborted"},
 				})
+			case "REGISTER", "VERIFY":
+				dc.SendMessage(&irc.Message{
+					Prefix:  dc.srv.prefix(),
+					Command: "FAIL",
+					Params:  []string{pendingCmd.msg.Command, "TEMPORARILY_UNAVAILABLE", pendingCmd.msg.Params[0], "Command aborted"},
+				})
 			default:
 				panic(fmt.Errorf("Unsupported pending command %q", pendingCmd.msg.Command))
 			}
@@ -318,7 +325,7 @@ func (uc *upstreamConn) sendNextPendingCommand(cmd string) {
 
 func (uc *upstreamConn) enqueueCommand(dc *downstreamConn, msg *irc.Message) {
 	switch msg.Command {
-	case "LIST", "WHO", "AUTHENTICATE":
+	case "LIST", "WHO", "AUTHENTICATE", "REGISTER", "VERIFY":
 		// Supported
 	default:
 		panic(fmt.Errorf("Unsupported pending command %q", msg.Command))
@@ -633,6 +640,21 @@ func (uc *upstreamConn) handleMessage(msg *irc.Message) error {
 				Params:  []string{"END"},
 			})
 		}
+	case "REGISTER", "VERIFY":
+		if dc, cmd := uc.dequeueCommand(msg.Command); dc != nil {
+			if msg.Command == "REGISTER" {
+				var account, password string
+				if err := parseMessageParams(msg, nil, &account); err != nil {
+					return err
+				}
+				if err := parseMessageParams(cmd, nil, nil, &password); err != nil {
+					return err
+				}
+				uc.network.autoSaveSASLPlain(context.TODO(), account, password)
+			}
+
+			dc.SendMessage(msg)
+		}
 	case irc.RPL_WELCOME:
 		uc.registered = true
 		uc.logger.Printf("connection registered")
@@ -1569,12 +1591,9 @@ func (uc *upstreamConn) handleMessage(msg *irc.Message) error {
 			return err
 		}
 
-		if command == "LIST" || command == "WHO" {
+		if dc, _ := uc.dequeueCommand(command); dc != nil && downstreamID == 0 {
-			dc, _ := uc.dequeueCommand(command)
-			if dc != nil && downstreamID == 0 {
 			downstreamID = dc.id
 		}
-		}
 
 		uc.forEachDownstreamByID(downstreamID, func(dc *downstreamConn) {
 			dc.SendMessage(&irc.Message{
@@ -1583,6 +1602,19 @@ func (uc *upstreamConn) handleMessage(msg *irc.Message) error {
 				Params:  []string{dc.nick, command, reason},
 			})
 		})
+	case "FAIL":
+		var command string
+		if err := parseMessageParams(msg, &command); err != nil {
+			return err
+		}
+
+		if dc, _ := uc.dequeueCommand(command); dc != nil && downstreamID == 0 {
+			downstreamID = dc.id
+		}
+
+		uc.forEachDownstreamByID(downstreamID, func(dc *downstreamConn) {
+			dc.SendMessage(msg)
+		})
 	case "ACK":
 		// Ignore
 	case irc.RPL_NOWAWAY, irc.RPL_UNAWAY: