From 16568c5ab7b6e037aca229c2409396eb1964431c Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Sun, 8 Jun 2025 16:33:39 -0400
Subject: [PATCH] fix #2270

REGISTER should strip the guest format when applicable, same as NS REGISTER.
---
 default.yaml     |  2 +-
 irc/handlers.go  | 17 ++++++++++++++---
 traditional.yaml |  2 +-
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/default.yaml b/default.yaml
index 000cbd89..f0342204 100644
--- a/default.yaml
+++ b/default.yaml
@@ -522,7 +522,7 @@ accounts:
         # 1. these nicknames cannot be registered or reserved
         # 2. if a client is automatically renamed by the server,
         #    this is the template that will be used (e.g., Guest-nccj6rgmt97cg)
-        # 3. if enforce-guest-format (see below) is enabled, clients without
+        # 3. if force-guest-format (see below) is enabled, clients without
         #    a registered account will have this template applied to their
         #    nicknames (e.g., 'katie' will become 'Guest-katie')
         guest-nickname-format: "Guest-*"
diff --git a/irc/handlers.go b/irc/handlers.go
index 2b6c23c6..c606637f 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -2907,11 +2907,23 @@ func quitHandler(server *Server, client *Client, msg ircmsg.Message, rb *Respons
 
 // REGISTER < account | * > < email | * > <password>
 func registerHandler(server *Server, client *Client, msg ircmsg.Message, rb *ResponseBuffer) (exiting bool) {
-	accountName := client.Nick()
-	if accountName == "*" {
+	var accountName string
+	if client.registered {
+		accountName = client.Nick()
+	} else {
 		accountName = client.preregNick
 	}
 
+	config := server.Config()
+	if client.registered && config.Accounts.NickReservation.ForceGuestFormat {
+		matches := config.Accounts.NickReservation.guestRegexp.FindStringSubmatch(accountName)
+		if matches == nil || len(matches) < 2 {
+			rb.Add(nil, server.name, "FAIL", "REGISTER", "INVALID_USERNAME", utils.SafeErrorParam(accountName), client.t("Username invalid or not given"))
+			return
+		}
+		accountName = matches[1]
+	}
+
 	switch msg.Params[0] {
 	case "*", accountName:
 		// ok
@@ -2928,7 +2940,6 @@ func registerHandler(server *Server, client *Client, msg ircmsg.Message, rb *Res
 		return
 	}
 
-	config := server.Config()
 	if !config.Accounts.Registration.Enabled {
 		rb.Add(nil, server.name, "FAIL", "REGISTER", "DISALLOWED", accountName, client.t("Account registration is disabled"))
 		return
diff --git a/traditional.yaml b/traditional.yaml
index c4c16e0e..df6ff052 100644
--- a/traditional.yaml
+++ b/traditional.yaml
@@ -494,7 +494,7 @@ accounts:
         # 1. these nicknames cannot be registered or reserved
         # 2. if a client is automatically renamed by the server,
         #    this is the template that will be used (e.g., Guest-nccj6rgmt97cg)
-        # 3. if enforce-guest-format (see below) is enabled, clients without
+        # 3. if force-guest-format (see below) is enabled, clients without
         #    a registered account will have this template applied to their
         #    nicknames (e.g., 'katie' will become 'Guest-katie')
         guest-nickname-format: "Guest-*"