From f8b39cfe61fc95d0bbb5a7e008541ff21aaafe37 Mon Sep 17 00:00:00 2001
From: Daniel Oaks <daniel@danieloaks.net>
Date: Sun, 21 Jan 2018 13:13:20 +1000
Subject: [PATCH] Send fake channel joins on RESUME

---
 irc/channel.go | 26 +++++++++++++++-----------
 irc/client.go  | 14 ++++----------
 irc/server.go  | 23 +++++++++++++++++++++--
 3 files changed, 40 insertions(+), 23 deletions(-)

diff --git a/irc/channel.go b/irc/channel.go
index 6c4c77f8..54163c89 100644
--- a/irc/channel.go
+++ b/irc/channel.go
@@ -145,29 +145,33 @@ func (channel *Channel) IsRegistered() bool {
 	return channel.registeredFounder != ""
 }
 
-func (channel *Channel) regenerateMembersCache() {
+func (channel *Channel) regenerateMembersCache(noLocksNeeded bool) {
 	// this is eventually consistent even without holding stateMutex.Lock()
 	// throughout the update; all updates to `members` while holding Lock()
 	// have a serial order, so the call to `regenerateMembersCache` that
 	// happens-after the last one will see *all* the updates. then,
 	// `membersCacheMutex` ensures that this final read is correctly paired
 	// with the final write to `membersCache`.
-	channel.membersCacheMutex.Lock()
-	defer channel.membersCacheMutex.Unlock()
+	if !noLocksNeeded {
+		channel.membersCacheMutex.Lock()
+		defer channel.membersCacheMutex.Unlock()
+		channel.stateMutex.RLock()
+	}
 
-	channel.stateMutex.RLock()
 	result := make([]*Client, len(channel.members))
 	i := 0
 	for client := range channel.members {
 		result[i] = client
 		i++
 	}
-	channel.stateMutex.RUnlock()
-	channel.stateMutex.Lock()
+	if !noLocksNeeded {
+		channel.stateMutex.RUnlock()
+		channel.stateMutex.Lock()
+	}
 	channel.membersCache = result
-	channel.stateMutex.Unlock()
-	return
-
+	if !noLocksNeeded {
+		channel.stateMutex.Unlock()
+	}
 }
 
 // Names sends the list of users joined to the channel to the given client.
@@ -413,7 +417,7 @@ func (channel *Channel) Join(client *Client, key string) {
 	channel.members.Add(client)
 	firstJoin := len(channel.members) == 1
 	channel.stateMutex.Unlock()
-	channel.regenerateMembersCache()
+	channel.regenerateMembersCache(false)
 
 	client.addChannel(channel)
 
@@ -722,7 +726,7 @@ func (channel *Channel) Quit(client *Client) {
 	channel.stateMutex.Lock()
 	channel.members.Remove(client)
 	channel.stateMutex.Unlock()
-	channel.regenerateMembersCache()
+	channel.regenerateMembersCache(false)
 
 	client.removeChannel(channel)
 }
diff --git a/irc/client.go b/irc/client.go
index 056212e9..ce55f92b 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -380,10 +380,12 @@ func (client *Client) TryResume() {
 	for channel := range oldClient.channels {
 		channel.stateMutex.Lock()
 
+		client.resumeDetails.SendFakeJoinsFor = append(client.resumeDetails.SendFakeJoinsFor, channel.name)
+
 		oldModeSet := channel.members[oldClient]
 		channel.members.Remove(oldClient)
 		channel.members[client] = oldModeSet
-		channel.regenerateMembersCache()
+		channel.regenerateMembersCache(true)
 
 		// send join for old clients
 		for member := range channel.members {
@@ -397,7 +399,7 @@ func (client *Client) TryResume() {
 				member.Send(nil, client.nickMaskString, "JOIN", channel.name)
 			}
 
-			//TODO(dan): send priv modes
+			//TODO(dan): send priv modes for fake new join
 		}
 
 		channel.stateMutex.Unlock()
@@ -652,26 +654,18 @@ func (client *Client) destroy(beingResumed bool) {
 		}
 	}
 
-	fmt.Println("2")
-
 	// clean up server
 	if !beingResumed {
 		client.server.clients.Remove(client)
 	}
 
-	fmt.Println("3")
-
 	// clean up self
 	if client.idletimer != nil {
 		client.idletimer.Stop()
 	}
 
-	fmt.Println("4")
-
 	client.socket.Close()
 
-	fmt.Println("5")
-
 	// send quit messages to friends
 	if !beingResumed {
 		for friend := range friends {
diff --git a/irc/server.go b/irc/server.go
index 9ab0dc1f..16a7d537 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -447,6 +447,24 @@ func (server *Server) tryRegister(c *Client) {
 	if server.logger.IsLoggingRawIO() {
 		c.Notice(rawIONotice)
 	}
+
+	// if resumed, send fake channel joins
+	if c.resumeDetails != nil {
+		for _, name := range c.resumeDetails.SendFakeJoinsFor {
+			channel := server.channels.Get(name)
+			if channel == nil {
+				continue
+			}
+
+			if c.capabilities.Has(caps.ExtendedJoin) {
+				c.Send(nil, c.nickMaskString, "JOIN", channel.name, c.account.Name, c.realname)
+			} else {
+				c.Send(nil, c.nickMaskString, "JOIN", channel.name)
+			}
+			channel.SendTopic(c)
+			channel.Names(c)
+		}
+	}
 }
 
 // t returns the translated version of the given string, based on the languages configured by the client.
@@ -2077,8 +2095,9 @@ func lusersHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool {
 
 // ResumeDetails are the details that we use to resume connections.
 type ResumeDetails struct {
-	OldNick   string
-	Timestamp *time.Time
+	OldNick          string
+	Timestamp        *time.Time
+	SendFakeJoinsFor []string
 }
 
 // RESUME <oldnick> [timestamp]