From bbb5e79f59d930d813abe01a5e2cab892bbd890f Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Thu, 30 Apr 2020 16:10:39 +0200
Subject: [PATCH] Introduce permanentUpstreamCaps

---
 upstream.go | 139 ++++++++++++++++++++++++++++------------------------
 1 file changed, 76 insertions(+), 63 deletions(-)

diff --git a/upstream.go b/upstream.go
index cf49c57..3fd367c 100644
--- a/upstream.go
+++ b/upstream.go
@@ -15,6 +15,16 @@ import (
 	"gopkg.in/irc.v3"
 )
 
+// permanentUpstreamCaps is the static list of upstream capabilities always
+// requested when supported.
+var permanentUpstreamCaps = map[string]bool{
+	"away-notify":      true,
+	"batch":            true,
+	"labeled-response": true,
+	"message-tags":     true,
+	"server-time":      true,
+}
+
 type upstreamChannel struct {
 	Name         string
 	conn         *upstreamConn
@@ -1209,7 +1219,7 @@ func (uc *upstreamConn) handleSupportedCaps(capsStr string) {
 
 func (uc *upstreamConn) requestCaps() {
 	var requestCaps []string
-	for _, c := range []string{"message-tags", "batch", "labeled-response", "server-time", "away-notify"} {
+	for c := range permanentUpstreamCaps {
 		if _, ok := uc.supportedCaps[c]; ok && !uc.caps[c] {
 			requestCaps = append(requestCaps, c)
 		}
@@ -1219,12 +1229,72 @@ func (uc *upstreamConn) requestCaps() {
 		requestCaps = append(requestCaps, "sasl")
 	}
 
-	if len(requestCaps) > 0 {
-		uc.SendMessage(&irc.Message{
-			Command: "CAP",
-			Params:  []string{"REQ", strings.Join(requestCaps, " ")},
-		})
+	if len(requestCaps) == 0 {
+		return
 	}
+
+	uc.SendMessage(&irc.Message{
+		Command: "CAP",
+		Params:  []string{"REQ", strings.Join(requestCaps, " ")},
+	})
+}
+
+func (uc *upstreamConn) requestSASL() bool {
+	if uc.network.SASL.Mechanism == "" {
+		return false
+	}
+
+	v, ok := uc.supportedCaps["sasl"]
+	if !ok {
+		return false
+	}
+	if v != "" {
+		mechanisms := strings.Split(v, ",")
+		found := false
+		for _, mech := range mechanisms {
+			if strings.EqualFold(mech, uc.network.SASL.Mechanism) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return false
+		}
+	}
+
+	return true
+}
+
+func (uc *upstreamConn) handleCapAck(name string, ok bool) error {
+	uc.caps[name] = ok
+
+	switch name {
+	case "sasl":
+		if !ok {
+			uc.logger.Printf("server refused to acknowledge the SASL capability")
+			return nil
+		}
+
+		auth := &uc.network.SASL
+		switch auth.Mechanism {
+		case "PLAIN":
+			uc.logger.Printf("starting SASL PLAIN authentication with username %q", auth.Plain.Username)
+			uc.saslClient = sasl.NewPlainClient("", auth.Plain.Username, auth.Plain.Password)
+		default:
+			return fmt.Errorf("unsupported SASL mechanism %q", name)
+		}
+
+		uc.SendMessage(&irc.Message{
+			Command: "AUTHENTICATE",
+			Params:  []string{auth.Mechanism},
+		})
+	default:
+		if permanentUpstreamCaps[name] {
+			break
+		}
+		uc.logger.Printf("received CAP ACK/NAK for a cap we don't support: %v", name)
+	}
+	return nil
 }
 
 func splitSpace(s string) []string {
@@ -1290,63 +1360,6 @@ func (uc *upstreamConn) runUntilRegistered() error {
 	return nil
 }
 
-func (uc *upstreamConn) requestSASL() bool {
-	if uc.network.SASL.Mechanism == "" {
-		return false
-	}
-
-	v, ok := uc.supportedCaps["sasl"]
-	if !ok {
-		return false
-	}
-	if v != "" {
-		mechanisms := strings.Split(v, ",")
-		found := false
-		for _, mech := range mechanisms {
-			if strings.EqualFold(mech, uc.network.SASL.Mechanism) {
-				found = true
-				break
-			}
-		}
-		if !found {
-			return false
-		}
-	}
-
-	return true
-}
-
-func (uc *upstreamConn) handleCapAck(name string, ok bool) error {
-	uc.caps[name] = ok
-
-	switch name {
-	case "sasl":
-		if !ok {
-			uc.logger.Printf("server refused to acknowledge the SASL capability")
-			return nil
-		}
-
-		auth := &uc.network.SASL
-		switch auth.Mechanism {
-		case "PLAIN":
-			uc.logger.Printf("starting SASL PLAIN authentication with username %q", auth.Plain.Username)
-			uc.saslClient = sasl.NewPlainClient("", auth.Plain.Username, auth.Plain.Password)
-		default:
-			return fmt.Errorf("unsupported SASL mechanism %q", name)
-		}
-
-		uc.SendMessage(&irc.Message{
-			Command: "AUTHENTICATE",
-			Params:  []string{auth.Mechanism},
-		})
-	case "message-tags", "labeled-response", "away-notify", "batch", "server-time":
-		// Nothing to do
-	default:
-		uc.logger.Printf("received CAP ACK/NAK for a cap we don't support: %v", name)
-	}
-	return nil
-}
-
 func (uc *upstreamConn) readMessages(ch chan<- event) error {
 	for {
 		msg, err := uc.ReadMessage()