From 75bd63d0bceded707df9e808280734e14368b732 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Tue, 4 Jul 2023 21:44:18 -0400
Subject: [PATCH] add channel autojoin feature

See discussion on #2077
---
 default.yaml     |  8 +++++++-
 irc/config.go    |  1 +
 irc/server.go    | 14 ++++++++++++++
 traditional.yaml |  8 +++++++-
 4 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/default.yaml b/default.yaml
index 93cef8df..44b170e4 100644
--- a/default.yaml
+++ b/default.yaml
@@ -364,7 +364,7 @@ server:
     # in a "closed-loop" system where you control the server and all the clients,
     # you may want to increase the maximum (non-tag) length of an IRC line from
     # the default value of 512. DO NOT change this on a public server:
-    # max-line-len: 512
+    #max-line-len: 512
 
     # send all 0's as the LUSERS (user counts) output to non-operators; potentially useful
     # if you don't want to publicize how popular the server is
@@ -615,6 +615,12 @@ channels:
     # (0 or omit for no expiration):
     invite-expiration: 24h
 
+    # channels that new clients will automatically join. this should be used with
+    # caution, since traditional IRC users will likely view it as an antifeature.
+    # it may be useful in small community networks that have a single "primary" channel:
+    #auto-join:
+    #    - "#lounge"
+
 # operator classes:
 # an operator has a single "class" (defining a privilege level), which can include
 # multiple "capabilities" (defining privileged actions they can take). all
diff --git a/irc/config.go b/irc/config.go
index 5ae49660..c723075c 100644
--- a/irc/config.go
+++ b/irc/config.go
@@ -644,6 +644,7 @@ type Config struct {
 		}
 		ListDelay        time.Duration    `yaml:"list-delay"`
 		InviteExpiration custime.Duration `yaml:"invite-expiration"`
+		AutoJoin         []string         `yaml:"auto-join"`
 	}
 
 	OperClasses map[string]*OperClassConfig `yaml:"oper-classes"`
diff --git a/irc/server.go b/irc/server.go
index 6978c87e..fbf95beb 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -394,6 +394,12 @@ func (server *Server) tryRegister(c *Client, session *Session) (exiting bool) {
 	}
 
 	server.playRegistrationBurst(session)
+
+	if len(config.Channels.AutoJoin) > 0 {
+		// only applicable to new clients, not reattaches:
+		server.handleAutojoins(session, config.Channels.AutoJoin)
+	}
+
 	return false
 }
 
@@ -502,6 +508,14 @@ func (server *Server) MOTD(client *Client, rb *ResponseBuffer) {
 	rb.Add(nil, server.name, RPL_ENDOFMOTD, client.nick, client.t("End of MOTD command"))
 }
 
+func (server *Server) handleAutojoins(session *Session, channelNames []string) {
+	rb := NewResponseBuffer(session)
+	for _, chname := range channelNames {
+		server.channels.Join(session.client, chname, "", false, rb)
+	}
+	rb.Send(true)
+}
+
 func (client *Client) whoisChannelsNames(target *Client, multiPrefix bool, hasPrivs bool) []string {
 	var chstrs []string
 	targetInvis := target.HasMode(modes.Invisible)
diff --git a/traditional.yaml b/traditional.yaml
index 1291771c..811a1e7d 100644
--- a/traditional.yaml
+++ b/traditional.yaml
@@ -337,7 +337,7 @@ server:
     # in a "closed-loop" system where you control the server and all the clients,
     # you may want to increase the maximum (non-tag) length of an IRC line from
     # the default value of 512. DO NOT change this on a public server:
-    # max-line-len: 512
+    #max-line-len: 512
 
     # send all 0's as the LUSERS (user counts) output to non-operators; potentially useful
     # if you don't want to publicize how popular the server is
@@ -587,6 +587,12 @@ channels:
     # (0 or omit for no expiration):
     invite-expiration: 24h
 
+    # channels that new clients will automatically join. this should be used with
+    # caution, since traditional IRC users will likely view it as an antifeature.
+    # it may be useful in small community networks that have a single "primary" channel:
+    #auto-join:
+    #    - "#lounge"
+
 # operator classes:
 # an operator has a single "class" (defining a privilege level), which can include
 # multiple "capabilities" (defining privileged actions they can take). all