From 26cdb4cf36d93912b4a005239b855d121204aef2 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Wed, 25 Aug 2021 22:31:38 -0400
Subject: [PATCH] fix #1650

RPL_WHOISACTUALLY should display some arbitrarily chosen IP address and
hostname.
---
 irc/client.go  |  6 +-----
 irc/getters.go | 11 +++++++++++
 irc/server.go  |  3 ++-
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/irc/client.go b/irc/client.go
index 9376927e..fc9f8015 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -613,11 +613,7 @@ func (client *Client) getIPNoMutex() net.IP {
 
 // IPString returns the IP address of this client as a string.
 func (client *Client) IPString() string {
-	ip := client.IP().String()
-	if 0 < len(ip) && ip[0] == ':' {
-		ip = "0" + ip
-	}
-	return ip
+	return utils.IPStringToHostname(client.IP().String())
 }
 
 // t returns the translated version of the given string, based on the languages configured by the client.
diff --git a/irc/getters.go b/irc/getters.go
index c2fd54d2..0e49c9fc 100644
--- a/irc/getters.go
+++ b/irc/getters.go
@@ -145,6 +145,17 @@ func (client *Client) removeSession(session *Session) (success bool, length int)
 	return
 }
 
+// #1650: show an arbitrarily chosen session IP and hostname in RPL_WHOISACTUALLY
+func (client *Client) getWhoisActually() (ip net.IP, hostname string) {
+	client.stateMutex.RLock()
+	defer client.stateMutex.RUnlock()
+
+	for _, session := range client.sessions {
+		return session.IP(), session.rawHostname
+	}
+	return utils.IPv4LoopbackAddress, client.server.name
+}
+
 func (client *Client) Nick() string {
 	client.stateMutex.RLock()
 	defer client.stateMutex.RUnlock()
diff --git a/irc/server.go b/irc/server.go
index 3e041c7b..6766302f 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -482,7 +482,8 @@ func (client *Client) getWhoisOf(target *Client, hasPrivs bool, rb *ResponseBuff
 		}
 	}
 	if client == target || oper.HasRoleCapab("ban") {
-		rb.Add(nil, client.server.name, RPL_WHOISACTUALLY, cnick, tnick, fmt.Sprintf("%s@%s", targetInfo.username, target.RawHostname()), target.IPString(), client.t("Actual user@host, Actual IP"))
+		ip, hostname := target.getWhoisActually()
+		rb.Add(nil, client.server.name, RPL_WHOISACTUALLY, cnick, tnick, fmt.Sprintf("%s@%s", targetInfo.username, hostname), utils.IPStringToHostname(ip.String()), client.t("Actual user@host, Actual IP"))
 	}
 	if client == target || oper.HasRoleCapab("samode") {
 		rb.Add(nil, client.server.name, RPL_WHOISMODES, cnick, tnick, fmt.Sprintf(client.t("is using modes +%s"), target.modes.String()))