From 4ea61002cc170f20ffa79c7d1f78dd6d85610184 Mon Sep 17 00:00:00 2001
From: Mikhail Efremov <sem@altlinux.org>
Date: Thu, 13 Dec 2012 19:20:14 +0400
Subject: [PATCH] revdns: Added IPv6 support.

---
 alterator-net-functions/tools/revdns | 122 ++++++++++++++++++++-------
 1 file changed, 92 insertions(+), 30 deletions(-)

diff --git a/alterator-net-functions/tools/revdns b/alterator-net-functions/tools/revdns
index 60fdd7e..9a6d15d 100755
--- a/alterator-net-functions/tools/revdns
+++ b/alterator-net-functions/tools/revdns
@@ -1,17 +1,15 @@
 #!/bin/sh -efu
+. alterator-net-functions
 
-ip="${1%%/*}"
-mask="${1##*/}"
-
-rdns_net()
+ipv4_rdns_net()
 {
-    local net="$1";shift
-    local pos="$1";shift
-    local inc="$1";shift
+	local net="$1";shift
+	local pos="$1";shift
+	local inc="$1";shift
 
-    local IFS='.'
-    set -- $net
-    case "$pos" in
+	local IFS='.'
+	set -- $net
+	case "$pos" in
 	1)
 	    printf "%s\n" "$(( $1 + $inc ))"
 	;;
@@ -24,27 +22,91 @@ rdns_net()
     esac
 }
 
-net="$(netname "$ip/$mask"|cut -f1)"
-net="${net%%/$mask}"
+ipv4_revdns()
+{
+	local nprefix pos i num
+	local net="$(netname "$ip/$prefix"|cut -f1)"
+	net="${net%%/$prefix}"
 
-if [ "$mask" -gt 0 -a "$mask" -le 8 ];then
-    nmask=8
-    pos=1
+	if [ "$prefix" -gt 0 -a "$prefix" -le 8 ];then
+		nprefix=8
+		pos=1
 
-elif [ "$mask" -gt 8 -a "$mask" -le 16 ];then
-    nmask=16
-    pos=2
-elif [ "$mask" -gt 16 -a "$mask" -le 24 ];then
-    nmask=24
-    pos=3
-else
-    mask=24
-    nmask=24
-    pos=3
-fi
+	elif [ "$prefix" -gt 8 -a "$prefix" -le 16 ];then
+		nprefix=16
+		pos=2
+	elif [ "$prefix" -gt 16 -a "$prefix" -le 24 ];then
+		nprefix=24
+		pos=3
+	else
+		prefix=24
+		nprefix=24
+		pos=3
+	fi
 
-num="$(( 2**($nmask - $mask) - 1 ))"
+	num="$(( 2**($nprefix - $prefix) - 1 ))"
+
+	for i in `seq 0 $num` ;do
+		ipv4_rdns_net "$net" "$pos" "$i"
+	done
+}
+
+ipv6_rdns_net()
+{
+	local net="$1";shift
+	local pos="$1";shift
+	local inc="$1";shift
+	local c=0
+	local out tmp i p
+
+	net="$(ipv6addr_expand "${net%%/$prefix}")"
+
+	local IFS=':'
+	for i in $net; do
+		[ $c -lt $pos ] || break
+		tmp="$tmp$i"
+		c=$(($c + 1))
+	done
+
+	tmp="$tmp$(printf '%04x' $((0x$i + 0x$inc)))"
+	for p in $(echo $tmp | sed -r 's;([[:xdigit:]]);\1:;g'); do
+		out="$p${out:+.}$out"
+	done
+	echo "$out"
+}
+
+ipv6_revdns()
+{
+	local nprefix pos i num
+	local net="$(ipv6_network "$ip/$prefix")"
+
+	pos=$(($prefix / 16))
+	nprefix=$((16 - $prefix % 16))
+	if [ $nprefix -eq 16 ]; then
+		nprefix=0
+		pos=$(($pos - 1))
+	fi
+
+	num="$(( 2**$nprefix - 1 ))"
+
+	for i in $(printf "%x " $(seq 0 $num)) ;do
+		ipv6_rdns_net "$net" "$pos" "$i"
+	done
+}
+
+ip="${1%%/*}"
+prefix="${1##*/}"
+ipv="${2:-4}"
+
+case "$ipv" in
+	4) valid_ipv4 "$ip" &&
+	   valid_ipv4prefix "$prefix" &&
+	   ipv4_revdns
+	;;
+	6) valid_ipv6addr "$ip" &&
+	   valid_ipv6prefix "$prefix" &&
+	   ipv6_revdns
+	;;
+	*) exit 1 ;;
+esac
 
-for i in `seq 0 $num` ;do
-    rdns_net "$net" "$pos" "$i"
-done