From 3aabf9f83ec385ca735479fcbfa7c8c142e1509a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jake=20Buchholz=20G=C3=B6kt=C3=BCrk?= <tomalok@gmail.com>
Date: Thu, 29 May 2025 19:31:34 -0700
Subject: [PATCH] validate hostname value lengths

---
 CHANGELOG.md        |  3 +++
 lib/tiny-cloud/init | 16 +++++++++++-----
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9393de4..ed2a6e2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,9 @@
 
 * Alpine autoinstall - allow override disk and reboot and set swap (@ncopa)
 
+* Warn when hostname is too long (per RFC-1035) instead of setting invalid
+  value.
+
 
 ## 2024-12-03 - Tiny Cloud v3.1.0
 
diff --git a/lib/tiny-cloud/init b/lib/tiny-cloud/init
index 8eb7329..f633777 100644
--- a/lib/tiny-cloud/init
+++ b/lib/tiny-cloud/init
@@ -226,13 +226,19 @@ init__set_hostname() {
 		log -i -t "$phase" info "$ACTION: no hostname set"
 		return
 	fi
-
-	local host="${fqdn%%\.*}"
-	if [ -z "$host" ]; then
-		log -i -t "$phase" warning "$ACTION: invalid hostname '$fqdn'"
+	if [ ${#fqdn} -gt 255 ]; then
+		log -i -t "$phase" warning "$ACTION: hostname exceeds 255 chars '$fqdn'"
+		return 1
+	fi
+	local host="${fqdn%%\.*}"
+	if [ -z "$host" ]; then
+		log -i -t "$phase" warning "$ACTION: unable to extract short hostname from '$fqdn'"
+		return 1
+	fi
+	if [ ${#host} -gt 63 ]; then
+		log -i -t "$phase" warning "$ACTION: short hostname exceeds 63 chars '$host'"
 		return 1
 	fi
-
 	mkdir -p "$ETC"
 	echo "$host" > "$ETC"/hostname
 	$MOCK hostname -F "$ETC"/hostname