From 1ef41d6020f6e5c2e243dfa63d5615b0df2597e9 Mon Sep 17 00:00:00 2001
From: Alex Jaspersen <ajaspersen@google.com>
Date: Thu, 7 May 2020 00:16:22 +0000
Subject: [PATCH 1/3] Hide +i users from WHO * queries.

Fixes #990.
---
 irc/handlers.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/irc/handlers.go b/irc/handlers.go
index dbcb6793..3c7dfb1e 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -2637,7 +2637,9 @@ func whoHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Respo
 		}
 	} else {
 		for mclient := range server.clients.FindAll(mask) {
-			client.rplWhoReply(nil, mclient, rb)
+			if !mclient.HasMode(modes.Invisible) || isOper {
+				client.rplWhoReply(nil, mclient, rb)
+			}
 		}
 	}
 

From b3cfcc1289b7538c07a56458a97dd9824ab79063 Mon Sep 17 00:00:00 2001
From: Alex Jaspersen <ajaspersen@google.com>
Date: Thu, 7 May 2020 03:00:28 +0000
Subject: [PATCH 2/3] Show users in WHO queries if they are friends, i.e. they
 share a channel.

---
 irc/client.go   | 15 +++++++++++++++
 irc/handlers.go |  2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/irc/client.go b/irc/client.go
index b636678a..eb44cc9b 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -1022,6 +1022,21 @@ func (client *Client) ModeString() (str string) {
 	return "+" + client.modes.String()
 }
 
+// IsFriend() returns true if the given otherClient shares a channel with this client, or if they are the same user.
+func (client *Client) IsFriend(otherClient *Client) bool {
+	if client == otherClient {
+		return true
+	}
+
+	for _, channel := range client.Channels() {
+		if channel.hasClient(otherClient) {
+			return true
+		}
+	}
+
+	return false
+}
+
 // Friends refers to clients that share a channel with this client.
 func (client *Client) Friends(capabs ...caps.Capability) (result map[*Session]bool) {
 	result = make(map[*Session]bool)
diff --git a/irc/handlers.go b/irc/handlers.go
index 3c7dfb1e..fd53dd41 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -2637,7 +2637,7 @@ func whoHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Respo
 		}
 	} else {
 		for mclient := range server.clients.FindAll(mask) {
-			if !mclient.HasMode(modes.Invisible) || isOper {
+			if isOper || !mclient.HasMode(modes.Invisible) || mclient.IsFriend(client) {
 				client.rplWhoReply(nil, mclient, rb)
 			}
 		}

From a6e4a26cbbcac4f813004862b23d4ec725d89810 Mon Sep 17 00:00:00 2001
From: Alex Jaspersen <ajaspersen@google.com>
Date: Fri, 8 May 2020 01:55:47 +0000
Subject: [PATCH 3/3] Performance optimization for determining friends in WHO
 <mask>.

Construct a hash set of the user's channels and check that rather than
querying channel membership, to reduce the number of locks that need to be
acquired.
---
 irc/client.go   | 15 ---------------
 irc/handlers.go | 22 +++++++++++++++++++++-
 2 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/irc/client.go b/irc/client.go
index eb44cc9b..b636678a 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -1022,21 +1022,6 @@ func (client *Client) ModeString() (str string) {
 	return "+" + client.modes.String()
 }
 
-// IsFriend() returns true if the given otherClient shares a channel with this client, or if they are the same user.
-func (client *Client) IsFriend(otherClient *Client) bool {
-	if client == otherClient {
-		return true
-	}
-
-	for _, channel := range client.Channels() {
-		if channel.hasClient(otherClient) {
-			return true
-		}
-	}
-
-	return false
-}
-
 // Friends refers to clients that share a channel with this client.
 func (client *Client) Friends(capabs ...caps.Capability) (result map[*Session]bool) {
 	result = make(map[*Session]bool)
diff --git a/irc/handlers.go b/irc/handlers.go
index fd53dd41..c337f88f 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -2636,8 +2636,28 @@ func whoHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Respo
 			}
 		}
 	} else {
+		// Construct set of channels the client is in.
+		userChannels := make(map[*Channel]bool)
+		for _, channel := range client.Channels() {
+			userChannels[channel] = true
+		}
+
+		// Another client is a friend if they share at least one channel, or they are the same client.
+		isFriend := func(otherClient *Client) bool {
+			if client == otherClient {
+				return true
+			}
+
+			for _, channel := range otherClient.Channels() {
+				if userChannels[channel] {
+					return true
+				}
+			}
+			return false
+		}
+
 		for mclient := range server.clients.FindAll(mask) {
-			if isOper || !mclient.HasMode(modes.Invisible) || mclient.IsFriend(client) {
+			if isOper || !mclient.HasMode(modes.Invisible) || isFriend(mclient) {
 				client.rplWhoReply(nil, mclient, rb)
 			}
 		}