2 ##############################################################################
4 # This program is free software; you can redistribute it and/or modify
5 # it under the terms of the GNU General Public License version 2 as
6 # published by the Free Software Foundation.
8 # This program is distributed in the hope that it will be useful,
9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 # GNU General Public License for more details.
13 # Copyright (C) 2016 Eric Luehrsen
15 ##############################################################################
17 # Turn DHCP records into meaningful A, AAAA, and PTR records. Also lift a
18 # function from dnsmasq and use DHCPv4 MAC to find IPV6 SLAAC hosts.
21 # "hostfile" = where this script will cache host DNS data
22 # "domain" = text domain suffix
23 # "bslaac" = boolean, use DHCPv4 MAC to find GA and ULA IPV6 SLAAC
24 # "bisolt" = boolean, format <host>.<network>.<domain>. so you can isolate
25 # "bconf" = boolean, write conf file format rather than pipe records
27 ##############################################################################
30 # We need to pick out DHCP v4 or v6 records
31 net = $2 ; id = $3 ; cls = $4 ; hst = $5 ; adr = $9 ; adr2 = $10
34 sub( /\/.*/, "", adr ) ;
35 sub( /.*\//, "", cdr ) ;
36 sub( /\/.*/, "", adr2 ) ;
37 sub( /.*\//, "", cdr2 ) ;
40 if ( hst !~ /^[[:alnum:]]([-[:alnum:]]*[[:alnum:]])?$/ ) {
41 # that is not a valid host name (RFC1123)
47 # TODO: this might be better with a substituion option,
48 # or per DHCP pool do-not-DNS option, but its getting busy here.
50 fqdn = sub( /\./, "-", fqdn ) ;
51 fqdn = tolower( hst "." fqdn "." domain ) ;
55 fqdn = tolower( hst "." domain ) ;
59 if ((cls == "ipv4") && (hst != "-") && (cdr == 32) && (NF == 9)) {
60 # IPV4 ; only for provided hostnames and full /32 assignments
61 # NF=9 ; odhcpd errata in field format without host name
62 ptr = adr ; qpr = "" ; split( ptr, ptr, "." ) ;
63 slaac = slaac_eui64( id ) ;
67 x = ( "local-data: \"" fqdn ". 300 IN A " adr "\"" ) ;
68 y = ( "local-data-ptr: \"" adr " 300 " fqdn "\"" ) ;
69 print ( x "\n" y "\n" ) > hostfile ;
73 for( i=1; i<=4; i++ ) { qpr = ( ptr[i] "." qpr) ; }
74 x = ( fqdn ". 300 IN A " adr ) ;
75 y = ( qpr "in-addr.arpa. 300 IN PTR " fqdn ) ;
76 print ( x "\n" y ) > hostfile ;
80 if (( bslaac == 1 ) && ( slaac != 0 )) {
81 # UCI option to discover IPV6 routed SLAAC addresses
82 # NOT TODO - ping probe take too long when added in awk-rule loop
83 cmd = ( "ip -6 --oneline route show dev " net ) ;
86 while ( ( cmd | getline adr ) > 0 ) {
87 if (( substr( adr, 1, 5 ) <= "fdff:" ) \
88 && ( index( adr, "anycast" ) == 0 ) \
89 && ( index( adr, "via" ) == 0 )) {
90 # GA or ULA routed addresses only (not LL or MC)
91 sub( /\/.*/, "", adr ) ;
95 if ( split( adr, tmp0, ":" ) > 8 ) {
96 sub( "::", ":", adr ) ;
101 x = ( "local-data: \"" fqdn ". 300 IN AAAA " adr "\"" ) ;
102 y = ( "local-data-ptr: \"" adr " 300 " fqdn "\"" ) ;
103 print ( x "\n" y "\n" ) > hostfile ;
107 qpr = ipv6_ptr( adr ) ;
108 x = ( fqdn ". 300 IN AAAA " adr ) ;
109 y = ( qpr ". 300 IN PTR " fqdn ) ;
110 print ( x "\n" y ) > hostfile ;
120 else if ((cls != "ipv4") && (hst != "-") && (9 <= NF) && (NF <= 10)) {
123 x = ( "local-data: \"" fqdn ". 300 IN AAAA " adr "\"" ) ;
124 y = ( "local-data-ptr: \"" adr " 300 " fqdn "\"" ) ;
125 print ( x "\n" y "\n" ) > hostfile ;
129 # only for provided hostnames and full /128 assignments
130 qpr = ipv6_ptr( adr ) ;
131 x = ( fqdn ". 300 IN AAAA " adr ) ;
132 y = ( qpr ". 300 IN PTR " fqdn ) ;
133 print ( x "\n" y ) > hostfile ;
139 x = ( "local-data: \"" fqdn ". 300 IN AAAA " adr2 "\"" ) ;
140 y = ( "local-data-ptr: \"" adr2 " 300 " fqdn "\"" ) ;
141 print ( x "\n" y "\n" ) > hostfile ;
145 # odhcp puts GA and ULA on the same line (position 9 and 10)
146 qpr2 = ipv6_ptr( adr2 ) ;
147 x = ( fqdn ". 300 IN AAAA " adr2 ) ;
148 y = ( qpr2 ". 300 IN PTR " fqdn ) ;
149 print ( x "\n" y ) > hostfile ;
155 # dump non-conforming lease records
159 ##############################################################################
161 function ipv6_ptr( ipv6, arpa, ary, end, i, j, new6, sz, start ) {
162 # IPV6 colon flexibility is a challenge when creating [ptr].ip6.arpa.
163 sz = split( ipv6, ary, ":" ) ; end = 9 - sz ;
166 for( i=1; i<=sz; i++ ) {
167 if( length(ary[i]) == 0 ) {
168 for( j=1; j<=end; j++ ) { ary[i] = ( ary[i] "0000" ) ; }
172 ary[i] = substr( ( "0000" ary[i] ), length( ary[i] )+5-4 ) ;
178 for( i = 2; i <= sz; i++ ) { new6 = ( new6 ary[i] ) ; }
179 start = length( new6 ) ;
180 for( i=start; i>0; i-- ) { arpa = ( arpa substr( new6, i, 1 ) ) ; } ;
181 gsub( /./, "&\.", arpa ) ; arpa = ( arpa "ip6.arpa" ) ;
186 ##############################################################################
188 function slaac_eui64( mac, ary, glbit, eui64 ) {
189 if ( length(mac) >= 12 ) {
190 # RFC2373 and use DHCPv4 registered MAC to find SLAAC addresses
191 split( mac , ary , "" ) ;
192 glbit = ( "0x" ary[2] ) ;
193 glbit = sprintf( "%d", glbit ) ;
194 glbit = or( glbit, 2 ) ;
195 ary[2] = sprintf( "%x", glbit ) ;
196 eui64 = ( ary[1] ary[2] ary[3] ary[4] ":" ary[5] ary[6] "ff:fe" ) ;
197 eui64 = ( eui64 ary[7] ary[8] ":" ary[9] ary[10] ary[11] ary[12] ) ;
208 ##############################################################################