Preserve Asuswrt-Merlin dnsmasq postconf hooks

internal/router/dnsmasq/dnsmasq.go

@@ -28,17 +28,21 @@ max-cache-ttl=0
 `
 
 const (
-	MerlinConfPath     = "/tmp/etc/dnsmasq.conf"
-	MerlinJffsConfDir  = "/jffs/configs"
-	MerlinJffsConfPath = "/jffs/configs/dnsmasq.conf"
-	MerlinPostConfPath = "/jffs/scripts/dnsmasq.postconf"
+	MerlinConfPath        = "/tmp/etc/dnsmasq.conf"
+	MerlinJffsConfDir     = "/jffs/configs"
+	MerlinJffsConfPath    = "/jffs/configs/dnsmasq.conf"
+	MerlinPostConfPath    = "/jffs/scripts/dnsmasq.postconf"
 )
 
-const MerlinPostConfMarker = `# GENERATED BY ctrld - EOF`
-const MerlinPostConfTmpl = `# GENERATED BY ctrld - DO NOT MODIFY
-
-#!/bin/sh
+const (
+	MerlinPostConfBeginMarker            = `# BEGIN ctrld`
+	MerlinPostConfEndMarker              = `# END ctrld`
+	MerlinSyntheticShebangMarker         = `# ctrld: synthetic shebang`
+	// MerlinPostConfMarker is the legacy end marker used by ctrld <= 1.5.7.
+	MerlinPostConfMarker = `# GENERATED BY ctrld - EOF`
+)
 
+const MerlinPostConfTmpl = `(
 config_file="$1"
 . /usr/sbin/helper.sh
 
@@ -66,9 +70,8 @@ if [ -n "$pid" ] && [ -f "/proc/${pid}/cmdline" ]; then
   # Change /etc/resolv.conf, which may be changed by WAN DNS setup
   pc_delete "nameserver" /etc/resolv.conf
   pc_append "nameserver 127.0.0.1" /etc/resolv.conf
-
-  exit 0
 fi
+)
 `
 
 type Upstream struct {