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#!/usr/bin/awk
##############################################################################
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# Copyright (C) 2016 Eric Luehrsen
#
##############################################################################
#
# Turn DHCP records into meaningful A, AAAA, and PTR records. Also lift a
# function from dnsmasq and use DHCPv4 MAC to find IPV6 SLAAC hosts.
#
# External Parameters
# "conffile" = Unbound configuration left for a restart
# "pipefile" = DNS entries for unbound-control standard input
# "domain" = text domain suffix
# "bslaac" = boolean, use DHCPv4 MAC to find GA and ULA IPV6 SLAAC
# "bisolt" = boolean, format <host>.<network>.<domain>. so you can isolate
# "bconf" = boolean, write conf file with pipe records
# "exclude_ipv6_ga" = boolean, exclude IPv6 GA addresses from local-data
#
##############################################################################
/^#/ {
# We need to pick out DHCP v4 or v6 records
net = $2 ; id = $3 ; cls = $4 ; hst = $5 ; adr = $9 ; adr2 = $10
cdr = adr ;
cdr2 = adr2 ;
sub( /\/.*/, "", adr ) ;
sub( /.*\//, "", cdr ) ;
sub( /\/.*/, "", adr2 ) ;
sub( /.*\//, "", cdr2 ) ;
gsub( /_/, "-", hst ) ;
if ( hst !~ /^[[:alnum:]]([-[:alnum:]]*[[:alnum:]])?$/ ) {
# that is not a valid host name (RFC1123)
# above replaced common error of "_" in host name with "-"
hst = "-" ;
}
if ( bisolt == 1 ) {
# TODO: this might be better with a substitution option,
# or per DHCP pool do-not-DNS option, but its getting busy here.
fqdn = net
gsub( /\./, "-", fqdn ) ;
fqdn = tolower( hst "." fqdn "." domain ) ;
}
else {
fqdn = tolower( hst "." domain ) ;
}
if ((cls == "ipv4") && (hst != "-") && (cdr == 32) && (NF == 9)) {
# IPV4 ; only for provided hostnames and full /32 assignments
# NF=9 ; odhcpd errata in field format without host name
ptr = adr ; qpr = "" ; split( ptr, ptrarr, "." ) ;
slaac = slaac_eui64( id ) ;
if ( bconf == 1 ) {
x = ( "local-data: \"" fqdn ". 300 IN A " adr "\"" ) ;
y = ( "local-data-ptr: \"" adr " 300 " fqdn "\"" ) ;
print ( x "\n" y "\n" ) > conffile ;
}
# always create the pipe file
for( i=1; i<=4; i++ ) { qpr = ( ptrarr[i] "." qpr) ; }
x = ( fqdn ". 300 IN A " adr ) ;
y = ( qpr "in-addr.arpa. 300 IN PTR " fqdn ) ;
print ( x "\n" y ) > pipefile ;
if (( bslaac == 1 ) && ( slaac != 0 )) {
# UCI option to discover IPV6 routed SLAAC addresses
# NOT TODO - ping probe take too long when added in awk-rule loop
cmd = ( "ip -6 --oneline route show dev " net ) ;
while ( ( cmd | getline adr ) > 0 ) {
if (( substr( adr, 1, 5 ) <= "fdff:" ) \
&& ( index( adr, "::/" ) != 0 ) \
&& ( index( adr, "anycast" ) == 0 ) \
&& ( index( adr, "via" ) == 0 )) {
if ( exclude_ipv6_ga == 1 && ipv6_in_range(adr) ) {
printf "Excluding GA IPv6 address: %s for %s\n", \
adr, fqdn | "logger -t unbound-odhcpd"
continue
}
sub( /\/.*/, "", adr ) ;
adr = ( adr slaac ) ;
if ( split( adr, tmp0, ":" ) > 8 ) {
sub( "::", ":", adr ) ;
}
if ( bconf == 1 ) {
x = ( "local-data: \"" fqdn ". 300 IN AAAA " adr "\"" ) ;
y = ( "local-data-ptr: \"" adr " 300 " fqdn "\"" ) ;
print ( x "\n" y "\n" ) > conffile ;
}
# always create the pipe file
qpr = ipv6_ptr( adr ) ;
x = ( fqdn ". 300 IN AAAA " adr ) ;
y = ( qpr ". 300 IN PTR " fqdn ) ;
print ( x "\n" y ) > pipefile ;
}
}
close( cmd ) ;
}
}
else if ((cls != "ipv4") && (hst != "-") && (9 <= NF) && (NF <= 10)) {
if (cdr == 128) {
if ( exclude_ipv6_ga == 1 && ipv6_in_range(adr) ) {
printf "Excluding GA IPv6 address: %s for %s\n", \
adr, fqdn | "logger -t unbound-odhcpd"
}
else {
if ( bconf == 1 ) {
x = ( "local-data: \"" fqdn ". 300 IN AAAA " adr "\"" ) ;
y = ( "local-data-ptr: \"" adr " 300 " fqdn "\"" ) ;
print ( x "\n" y "\n" ) > conffile ;
}
# only for provided hostnames and full /128 assignments
qpr = ipv6_ptr( adr ) ;
x = ( fqdn ". 300 IN AAAA " adr ) ;
y = ( qpr ". 300 IN PTR " fqdn ) ;
print ( x "\n" y ) > pipefile ;
}
}
if (cdr2 == 128) {
if ( exclude_ipv6_ga == 1 && ipv6_in_range(adr2) ) {
printf "Excluding GA IPv6 address: %s for %s\n", \
adr2, fqdn | "logger -t unbound-odhcpd"
}
else {
if ( bconf == 1 ) {
x = ( "local-data: \"" fqdn ". 300 IN AAAA " adr2 "\"" ) ;
y = ( "local-data-ptr: \"" adr2 " 300 " fqdn "\"" ) ;
print ( x "\n" y "\n" ) > conffile ;
}
# odhcp puts GA and ULA on the same line (position 9 and 10)
qpr2 = ipv6_ptr( adr2 ) ;
x = ( fqdn ". 300 IN AAAA " adr2 ) ;
y = ( qpr2 ". 300 IN PTR " fqdn ) ;
print ( x "\n" y ) > pipefile ;
}
}
}
else {
# dump non-conforming lease records
}
}
##############################################################################
function ipv6_ptr( ipv6, arpa, ary, end, m, n, new6, sz, start ) {
# IPV6 colon flexibility is a challenge when creating [ptr].ip6.arpa.
sz = split( ipv6, ary, ":" ) ; end = 9 - sz ;
for( m=1; m<=sz; m++ ) {
if( length(ary[m]) == 0 ) {
for( n=1; n<=end; n++ ) { ary[m] = ( ary[m] "0000" ) ; }
}
else {
ary[m] = substr( ( "0000" ary[m] ), length( ary[m] )+5-4 ) ;
}
}
new6 = ary[1] ;
for( m = 2; m <= sz; m++ ) { new6 = ( new6 ary[m] ) ; }
start = length( new6 ) ;
for( m=start; m>0; m-- ) { arpa = ( arpa substr( new6, m, 1 ) ) ; } ;
gsub( /./, "&.", arpa ) ; arpa = ( arpa "ip6.arpa" ) ;
return arpa ;
}
##############################################################################
function slaac_eui64( mac, ary, glbit, eui64 ) {
# Remove any colons from mac
gsub(":", "", mac) ;
if ( length(mac) >= 12 ) {
# RFC2373 and use DHCPv4 registered MAC to find SLAAC addresses
split( mac , ary , "" ) ;
glbit = ( "0x" ary[2] ) ;
glbit = sprintf( "%d", glbit ) ;
glbit = or( glbit, 2 ) ;
ary[2] = sprintf( "%x", glbit ) ;
eui64 = ( ary[1] ary[2] ary[3] ary[4] ":" ary[5] ary[6] "ff:fe" ) ;
eui64 = ( eui64 ary[7] ary[8] ":" ary[9] ary[10] ary[11] ary[12] ) ;
}
else {
eui64 = 0 ;
}
return eui64 ;
}
##############################################################################
function normalize_ipv6(ip, parts, normalized) {
# Remove any prefix length
sub(/\/.*/, "", ip);
# Handle compressed notation (::)
if (index(ip, "::") > 0) {
split(ip, parts, "::");
# Count colons to determine how many zero groups to insert
gsub(/:/, ":", parts[1]);
if (parts[2] != "") gsub(/:/, ":", parts[2]);
missing = 8 - (split(parts[1], tmp1, ":") + split(parts[2], tmp2, ":"));
# Build normalized address
normalized = parts[1];
for (i = 0; i < missing; i++) normalized = normalized ":0";
if (parts[2] != "") normalized = normalized ":" parts[2];
} else {
normalized = ip;
}
# Fill each group with leading zeros
split(normalized, parts, ":");
normalized = "";
for (i = 1; i <= length(parts); i++) {
if (parts[i] == "") parts[i] = "0";
while (length(parts[i]) < 4) {
parts[i] = "0" parts[i];
}
if (i > 1) normalized = normalized ":";
normalized = normalized parts[i];
}
return normalized;
}
function ipv6_in_range(ip) {
# Normalize the address first
ip = normalize_ipv6(ip);
# Check if it's in 2000::/3 range
# This covers 2000:: to 3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
first_group = substr(ip, 1, 4);
first_digit = substr(first_group, 1, 1);
return (first_digit == "2" || first_digit == "3");
}
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