From 78d9a84a6f2c6ca5582650e771ba2d6480fed03a Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Mon, 21 Mar 2022 16:09:45 +0100
Subject: [PATCH] Add support for RPL_VISIBLEHOST

---
 downstream.go | 12 ++++++++++++
 irc.go        |  1 +
 upstream.go   | 37 ++++++++++++++++++++++++++++++++++++-
 user.go       |  1 +
 4 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/downstream.go b/downstream.go
index 72cbff8..465c4c4 100644
--- a/downstream.go
+++ b/downstream.go
@@ -1132,6 +1132,17 @@ func (dc *downstreamConn) updateNick() {
 	}
 }
 
+func (dc *downstreamConn) updateHost() {
+	if uc := dc.upstream(); uc != nil && uc.hostname != "" && uc.hostname != dc.hostname {
+		dc.SendMessage(&irc.Message{
+			Prefix:  dc.prefix(),
+			Command: rpl_visiblehost,
+			Params:  []string{dc.nick, uc.hostname, "is now your visible host"},
+		})
+		dc.hostname = uc.hostname
+	}
+}
+
 func (dc *downstreamConn) updateRealname() {
 	if uc := dc.upstream(); uc != nil && uc.realname != dc.realname && dc.caps.IsEnabled("setname") {
 		dc.SendMessage(&irc.Message{
@@ -1471,6 +1482,7 @@ func (dc *downstreamConn) welcome(ctx context.Context) error {
 		})
 	}
 
+	dc.updateHost()
 	dc.updateRealname()
 	dc.updateAccount()
 
diff --git a/irc.go b/irc.go
index 720d3f2..876bd90 100644
--- a/irc.go
+++ b/irc.go
@@ -19,6 +19,7 @@ const (
 	rpl_topicwhotime  = "333"
 	rpl_whospcrpl     = "354"
 	rpl_whoisaccount  = "330"
+	rpl_visiblehost   = "396"
 	err_invalidcapcmd = "410"
 
 	// https://ircv3.net/specs/extensions/bot-mode
diff --git a/upstream.go b/upstream.go
index 1a8e066..d140b70 100644
--- a/upstream.go
+++ b/upstream.go
@@ -122,6 +122,7 @@ type upstreamConn struct {
 	nickCM      string
 	username    string
 	realname    string
+	hostname    string
 	modes       userModes
 	channels    upstreamChannelCasemapMap
 	caps        capRegistry
@@ -637,18 +638,52 @@ func (uc *upstreamConn) handleMessage(ctx context.Context, msg *irc.Message) err
 			})
 		}
 	case irc.RPL_LOGGEDIN:
-		if err := parseMessageParams(msg, nil, nil, &uc.account); err != nil {
+		var rawPrefix string
+		if err := parseMessageParams(msg, nil, &rawPrefix, &uc.account); err != nil {
 			return err
 		}
+
+		prefix := irc.ParsePrefix(rawPrefix)
+		uc.username = prefix.User
+		uc.hostname = prefix.Host
+
 		uc.logger.Printf("logged in with account %q", uc.account)
 		uc.forEachDownstream(func(dc *downstreamConn) {
 			dc.updateAccount()
+			dc.updateHost()
 		})
 	case irc.RPL_LOGGEDOUT:
+		var rawPrefix string
+		if err := parseMessageParams(msg, nil, &rawPrefix); err != nil {
+			return err
+		}
+
 		uc.account = ""
+
+		prefix := irc.ParsePrefix(rawPrefix)
+		uc.username = prefix.User
+		uc.hostname = prefix.Host
+
 		uc.logger.Printf("logged out")
 		uc.forEachDownstream(func(dc *downstreamConn) {
 			dc.updateAccount()
+			dc.updateHost()
+		})
+	case rpl_visiblehost:
+		var rawHost string
+		if err := parseMessageParams(msg, nil, &rawHost); err != nil {
+			return err
+		}
+
+		parts := strings.SplitN(rawHost, "@", 2)
+		if len(parts) == 2 {
+			uc.username, uc.hostname = parts[0], parts[1]
+		} else {
+			uc.hostname = rawHost
+		}
+
+		uc.forEachDownstream(func(dc *downstreamConn) {
+			dc.updateHost()
 		})
 	case irc.ERR_NICKLOCKED, irc.RPL_SASLSUCCESS, irc.ERR_SASLFAIL, irc.ERR_SASLTOOLONG, irc.ERR_SASLABORTED:
 		var info string
diff --git a/user.go b/user.go
index e8a05f7..bf1909f 100644
--- a/user.go
+++ b/user.go
@@ -567,6 +567,7 @@ func (u *user) run() {
 				}
 
 				dc.updateNick()
+				dc.updateHost()
 				dc.updateRealname()
 				dc.updateAccount()
 			})