From f4ad2416a70a89f0c19dc93aa1bd0e05a8203603 Mon Sep 17 00:00:00 2001
From: k4be <k4be@pirc.pl>
Date: Tue, 31 Aug 2021 13:38:14 +0200
Subject: [PATCH] Make server name check a bit more strict (% characters made
 sendnumeric generate invalid format strings)

---
 src/serv.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/serv.c b/src/serv.c
index 0921d6b7c..b25afdd0d 100644
--- a/src/serv.c
+++ b/src/serv.c
@@ -1087,6 +1087,7 @@ void charsys_check_for_changes(void)
 int valid_server_name(char *name)
 {
 	char *p;
+	int has_dot = 0;
 
 	if (!*name)
 		return 0; /* empty name */
@@ -1095,10 +1096,17 @@ int valid_server_name(char *name)
 		return 0; /* oversized */
 
 	for (p = name; *p; p++)
-		if ((*p <= ' ') || (*p > '~'))
+	{
+		if (*p == '.')
+		{
+			has_dot = 1;
+			continue;
+		}
+		if ((*p <= '0') || (*p > 'z'))
 			return 0; /* forbidden chars */
+	}
 
-	if (!strchr(name, '.'))
+	if (!has_dot)
 		return 0; /* no dot */
 
 	return 1;