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157 lines
4.7 KiB
157 lines
4.7 KiB
#!/usr/bin/awk
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##############################################################################
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License version 2 as
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# published by the Free Software Foundation.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# Copyright (C) 2016 Eric Luehrsen
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#
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##############################################################################
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#
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# Turn DHCP records into meaningful A, AAAA, and PTR records. Also lift a
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# function from dnsmasq and use DHCPv4 MAC to find IPV6 SLAAC hosts.
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#
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# External Parameters
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# "hostfile" = where this script will cache host DNS data
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# "domain" = text domain suffix
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# "bslaac" = boolean, use DHCPv4 MAC to find GA and ULA IPV6 SLAAC
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# "bisolt" = boolean, format <host>.<network>.<domain>. so you can isolate
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#
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##############################################################################
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/^#/ {
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# We need to pick out DHCP v4 or v6 records
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net = $2 ; id = $3 ; cls = $4 ; hst = $5 ; adr = $9 ;
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cdr = adr ;
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sub( /\/.*/, "", adr ) ;
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sub( /.*\//, "", cdr ) ;
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if ( bisolt == 1 ) {
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# TODO: this might be better with a substituion option,
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# or per DHCP pool do-not-DNS option, but its getting busy here.
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fqdn = net
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fqdn = sub( /\./, "-", fqdn ) ;
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fqdn = tolower( hst "." fqdn "." domain ) ;
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}
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else {
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fqdn = tolower( hst "." domain ) ;
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}
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if ( cls == "ipv4" ) {
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if ( NF == 8 ) {
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# odhcpd errata in field format without host name
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adr = $8 ; hst = "-" ; cdr = adr ;
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sub( /\/.*/, "", adr ) ;
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sub( /.*\//, "", cdr ) ;
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}
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if (( cdr == 32 ) && ( hst != "-" )) {
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# only for provided hostnames and full /32 assignments
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ptr = adr ; qpr = "" ; split( ptr, ptr, "." ) ;
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slaac = slaac_eui64( id ) ;
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for( i=1; i<=4; i++ ) { qpr = ( ptr[i] "." qpr) ; }
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# DHCP A and PTR records with FQDN
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x = ( fqdn ". 120 IN A " adr ) ;
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y = ( qpr "in-addr.arpa. 120 IN PTR " fqdn ) ;
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print ( x "\n" y ) > hostfile ;
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if ((bslaac == 1) && (slaac != 0)) {
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# UCI option to discover IPV6 routed SLAAC addresses
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# NOT TODO - ping probe take too long when added in awk-rule loop
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cmd = ( "ip -6 --oneline route show dev " net ) ;
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while ( ( cmd | getline adr ) > 0 ) {
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if (( substr( adr, 1, 5 ) <= "fd00:" ) \
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&& ( index( adr, "via" ) == 0 )) {
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# GA or ULA routed addresses only (not LL or MC)
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sub( /\/.*/, "", adr ) ;
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adr = ( adr slaac ) ;
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if ( split( adr, tmp0, ":" ) >= 8 ) { sub( "::", ":", adr ) ; }
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qpr = ipv6_ptr( adr ) ;
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x = ( fqdn ". 120 IN AAAA " adr ) ;
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y = ( qpr " 120 IN PTR " fqdn ) ;
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print ( x "\n" y ) > hostfile ;
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}
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}
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close( cmd ) ;
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}
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}
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}
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else {
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if (( cdr == 128 ) && ( hst != "-" )) {
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# only for provided hostnames and full /128 assignments
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qpr = ipv6_ptr( adr ) ;
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x = ( fqdn ". 120 IN AAAA " adr ) ;
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y = ( qpr " 120 IN PTR " fqdn ) ;
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print ( x "\n" y ) > hostfile ;
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}
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}
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}
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##############################################################################
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function ipv6_ptr( ipv6, arpa, ary, end, i, j, new6, sz, start ) {
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# IPV6 colon flexibility is a challenge when creating [ptr].ip6.arpa.
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sz = split( ipv6, ary, ":" ) ; end = 9 - sz ;
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for( i=1; i<=sz; i++ ) {
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if( length(ary[i]) == 0 ) {
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for( j=1; j<=end; j++ ) { ary[i] = ( ary[i] "0000" ) ; }
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}
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else {
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ary[i] = substr( ( "0000" ary[i] ), length( ary[i] )+5-4 ) ;
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}
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}
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new6 = ary[1] ;
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for( i = 2; i <= sz; i++ ) { new6 = ( new6 ary[i] ) ; }
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start = length( new6 ) ;
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for( i=start; i>0; i-- ) { arpa = ( arpa substr( new6, i, 1 ) ) ; } ;
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gsub( /./, "&\.", arpa ) ; arpa = ( arpa "ip6.arpa" ) ;
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return arpa ;
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}
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##############################################################################
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function slaac_eui64( mac, ary, glbit, eui64 ) {
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if ( length(mac) >= 12 ) {
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# RFC2373 and use DHCPv4 registered MAC to find SLAAC addresses
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split( mac , ary , "" ) ;
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glbit = ( "0x" ary[2] ) ;
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glbit = sprintf( "%d", glbit ) ;
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glbit = or( glbit, 2 ) ;
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ary[2] = sprintf( "%x", glbit ) ;
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eui64 = ( ary[1] ary[2] ary[3] ary[4] ":" ary[5] ary[6] "ff:fe" ) ;
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eui64 = ( eui64 ary[7] ary[8] ":" ary[9] ary[10] ary[11] ary[12] ) ;
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}
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else {
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eui64 = 0 ;
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}
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return eui64 ;
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}
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##############################################################################
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