| 1 | #!/usr/bin/perl
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| 2 | # Convert a BIND zone file to a hosts file
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| 3 | ##
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| 4 | # Copyright 2020 Kris Deugau <kdeugau@deepnet.cx>
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| 5 | #
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| 6 | # This program is free software: you can redistribute it and/or modify
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| 7 | # it under the terms of the GNU General Public License as published by
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| 8 | # the Free Software Foundation, either version 3 of the License, or
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| 9 | # (at your option) any later version.
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| 10 | #
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| 11 | # This program is distributed in the hope that it will be useful,
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| 12 | # but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | # GNU General Public License for more details.
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| 15 | #
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| 16 | # You should have received a copy of the GNU General Public License
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| 17 | # along with this program. If not, see <http://www.gnu.org/licenses/>.
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| 18 | ##
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| 19 |
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| 20 | use strict;
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| 21 | use warnings;
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| 22 | use Getopt::Long;
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| 23 |
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| 24 | use Data::Dumper;
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| 25 |
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| 26 | # push "the directory the script is in" into @INC
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| 27 | use FindBin;
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| 28 | use lib "$FindBin::RealBin/";
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| 29 |
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| 30 | use DNSDB;
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| 31 |
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| 32 | my @skipdefs;
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| 33 | my $skipfile;
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| 34 | my $dryrun = 0;
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| 35 | # CNAME chain depth
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| 36 | my $maxdepth = 3;
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| 37 |
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| 38 | GetOptions(
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| 39 | "skip=s" => \@skipdefs,
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| 40 | "skipfile=s" => \$skipfile,
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| 41 | "test|dry-run" => \$dryrun,
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| 42 | );
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| 43 |
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| 44 | my $zname = shift @ARGV;
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| 45 |
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| 46 | my $usage = "usage: bind2hosts zone [--skip pattern [--skip pattern2 ...]] [--skipfile file]
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| 47 | zonename < zonefile
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| 48 |
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| 49 | --skip
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| 50 | Specify a string to skip in the records. If an IP-like string is
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| 51 | used, and the zone is a reverse zone, it will also search for the
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| 52 | octet-reversed form. Specify multiple times to skip multiple
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| 53 | different record patterns.
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| 54 | --skipfile
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| 55 | A file containing patterns to skip. Patterns from the file and
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| 56 | any --skip arguments are merged.
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| 57 | zonename
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| 58 | The name of the zone to import. Required.
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| 59 |
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| 60 | Zone data will be read from STDIN.
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| 61 | ";
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| 62 | if (!$zname) {
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| 63 | die $usage;
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| 64 | }
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| 65 |
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| 66 | if ($skipfile) {
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| 67 | if (-f $skipfile) {
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| 68 | open SKIP, "<$skipfile";
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| 69 | while (<SKIP>) {
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| 70 | chomp;
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| 71 | push @skipdefs, $_;
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| 72 | }
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| 73 | close SKIP;
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| 74 | } else {
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| 75 | warn "skipfile $skipfile requested but it doesn't seem to exist. Continuing.\n";
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| 76 | }
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| 77 | }
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| 78 |
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| 79 | my $rev = 'n';
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| 80 | my $zid;
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| 81 |
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| 82 | my %amap;
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| 83 | my %namemap;
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| 84 | my %cmap;
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| 85 |
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| 86 | my $dnsdb = new DNSDB;
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| 87 |
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| 88 | # need an ultimate fallback for this one
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| 89 | my $defttl = 900;
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| 90 | my $origin = "$zname."; # to append to unqualified names
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| 91 | my $curlabel;
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| 92 | my $prevlabel;
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| 93 |
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| 94 | my $i = 0;
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| 95 |
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| 96 | # need to spin up a full state machine-ish thing, because BIND zone files are all about context
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| 97 | while (my $rec = <>) {
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| 98 | chomp $rec;
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| 99 | next if $rec =~ /^\s*$/;
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| 100 | next if $rec =~ /^\s*;/;
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| 101 | next if $rec =~ /^\s*\)/; # SOA closing (possibly other records too?)
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| 102 | # arguably should do some more targeted voodoo when parsing the SOA details
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| 103 |
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| 104 | my $skipflag = 0;
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| 105 | foreach (@skipdefs) {
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| 106 | if ($rec =~ /\Q$_\E/) {
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| 107 | $skipflag = 1;
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| 108 | # might want to do something with the skipped records someday
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| 109 | }
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| 110 | }
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| 111 | next if $skipflag;
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| 112 |
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| 113 | if (my ($macro,$mdetail) = ($rec =~ /^\s*\$(TTL|ORIGIN|INCLUDE)\s+(.+)/) ) {
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| 114 | # macro sort of thing; $TTL and $ORIGIN most common. $INCLUDE is a thing, expect it to be rare in live use tho
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| 115 | if ($macro eq 'TTL') {
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| 116 | # irrelevant for a hosts file
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| 117 | } elsif ($macro eq 'ORIGIN') {
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| 118 | # $ORIGIN supports cascading/nesting, by watching for fully-qualified names vs partial names.
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| 119 | if ($mdetail =~ /\.$/) {
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| 120 | $origin = $mdetail;
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| 121 | } else {
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| 122 | # append current origin to unqualified origin
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| 123 | $origin = "$mdetail.$origin";
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| 124 | }
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| 125 | }
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| 126 | ##fixme: should arguably handle $INCLUDE
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| 127 | # probably NOT going to handle $GENERATE, since that type of record set is best handled in DNS
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| 128 | next;
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| 129 | }
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| 130 |
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| 131 | # yay for special cases
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| 132 | $origin = '' if $origin eq '.';
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| 133 |
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| 134 | my $origrec = $rec;
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| 135 |
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| 136 | # leading whitespace indicates "same label as last record"
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| 137 | if ($rec =~ /^\s/) {
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| 138 | $curlabel = $prevlabel;
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| 139 | } else {
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| 140 | ($curlabel) = ($rec =~ /^([\w\@_.-]+)\s/);
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| 141 | }
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| 142 |
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| 143 | # magic name!
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| 144 | $curlabel = "$zname." if $curlabel eq '@';
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| 145 |
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| 146 | # append $ORIGIN if name is not fully qualified.
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| 147 | if ($curlabel !~ /\.$/) {
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| 148 | $curlabel .= ".$origin";
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| 149 | }
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| 150 |
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| 151 | # check for zone scope. skip bad records.
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| 152 | if ($curlabel !~ /$zname.$/) {
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| 153 | warn "bad record $origrec, maybe bad \$ORIGIN?\n";
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| 154 | next;
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| 155 | }
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| 156 |
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| 157 | # trim the label, if any
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| 158 | $rec =~ s/^([\w\@_.-]*)\s+//;
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| 159 |
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| 160 | # now that we've collected and trimmed off the record's label, unpack the class, TTL, and type.
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| 161 | # class and TTL may be omitted, and may appear in either class,TTL or TTL,class order.
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| 162 | my $nc = 0;
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| 163 | my %seenatoms;
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| 164 | # we don't actually use these but we have to recognize them
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| 165 | my $class = 'IN';
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| 166 | # not preset as we need to detect whether it's present in the record
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| 167 | my $ttl;
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| 168 | my $type;
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| 169 | my $badrec;
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| 170 | my $curatom = 'class';
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| 171 | eval {
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| 172 | for (; $nc < 3; $nc++) {
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| 173 | last if $type; # short-circuit if we've got a type, further data is record-specific.
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| 174 | my ($atom) = ($rec =~ /^([\w\d.]+)\s/);
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| 175 | # should be safe?
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| 176 | last if !$atom;
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| 177 | if ($atom =~ /^\d+$/) {
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| 178 | if (defined($ttl)) {
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| 179 | # we already have a TTL, so another all-numeric field is invalid.
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| 180 | die "bad record ($origrec)\n";
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| 181 | } else {
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| 182 | if ($curatom ne 'class' && $curatom ne 'ttl') {
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| 183 | die "bad record ($origrec)\n";
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| 184 | }
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| 185 | $curatom = 'ttl';
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| 186 | $ttl = $atom;
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| 187 | }
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| 188 | }
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| 189 | elsif ($atom =~ /^IN|CS|CH|HS$/) {
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| 190 | if ($atom =~ /CS|CH|HS/) {
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| 191 | die "unsupported class $atom in record ($origrec)\n";
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| 192 | }
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| 193 | $curatom = 'class';
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| 194 | $class = $atom;
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| 195 | }
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| 196 | elsif ($atom =~ /^[A-Z\d-]+/) {
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| 197 | # check against dnsadmin's internal list of known DNS types.
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| 198 | if ($reverse_typemap{$atom}) {
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| 199 | $type = $atom;
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| 200 | } else {
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| 201 | die "unknown type $atom in record ($origrec)\n";
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| 202 | }
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| 203 | $curatom = 'type';
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| 204 | }
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| 205 | $rec =~ s/^$atom\s*//;
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| 206 | } # class/type/TTL loop
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| 207 | };
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| 208 | if ($@) {
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| 209 | warn $@;
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| 210 | next;
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| 211 | }
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| 212 |
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| 213 | $ttl = $defttl if !defined($ttl);
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| 214 |
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| 215 | # Just In Case we need the original rdata after we've sliced off more pieces
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| 216 | my $rdata = $rec;
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| 217 | $prevlabel = $curlabel;
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| 218 |
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| 219 | ##fixme: squish this down for this script since SOA records are irrelevant
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| 220 | if ($type eq 'SOA') {
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| 221 | my ($ns, $adminmail) = ($rdata =~ /([\w.]+)\s+([\w.]+)\s+\(/);
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| 222 | die "Can't parse gibberish SOAish record: '$rdata'/'$origrec'\n" if !$ns;
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| 223 | $rdata =~ s/([\w.]+)\s+([\w.]+)\s+\(\s*//;
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| 224 |
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| 225 | # There are probably more efficient ways to do this but the SOA record
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| 226 | # format is essentially character based, not line-based.
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| 227 | # In theory the SOA serial etc may be spread over "many" lines, bounded by ().
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| 228 |
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| 229 | # Parse fields from $rdata if present
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| 230 | my @soabits;
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| 231 | my @soafirst = split /\s+/, $rdata;
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| 232 | while (my $f = shift @soafirst) {
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| 233 | last if $f !~ /^\d/;
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| 234 | push @soabits, $f;
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| 235 | }
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| 236 |
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| 237 | # Read more lines if we don't have enough SOA fields filled
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| 238 | while (scalar(@soabits) < 5) {
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| 239 | my $tmp = <>;
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| 240 | $tmp =~ s/^\s*//;
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| 241 | my @tmpsoa = split /\s+/, $tmp;
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| 242 | while (my $f = shift @tmpsoa) {
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| 243 | last if $f !~ /^\d/;
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| 244 | push @soabits, $f;
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| 245 | }
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| 246 | if (scalar(@soabits) == 5) {
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| 247 | last;
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| 248 | }
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| 249 | }
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| 250 | } # SOA
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| 251 |
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| 252 | ##fixme: trim dupes if possible
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| 253 |
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| 254 | elsif ($type eq 'A') {
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| 255 | # need the name->IP map so we can reverse-map the CNAMEs on output
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| 256 | push @{$amap{$curlabel}}, $rdata;
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| 257 | $namemap{$rdata}{$curlabel}++;
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| 258 | } # A record
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| 259 |
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| 260 | elsif ($type eq 'CNAME') {
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| 261 | $cmap{$curlabel} = $rdata.($rdata =~ /\./ ? '' : ".$origin");
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| 262 | } # CNAME record
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| 263 |
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| 264 | # all other record types are irrelevant for a hosts file
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| 265 |
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| 266 | } # <STDIN>
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| 267 |
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| 268 | #print Dumper \%cmap;
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| 269 |
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| 270 | # Walk the CNAME list and see if we can match the targets in-zone.
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| 271 | # Out-of-zone CNAMEs are out of scope for this conversion.
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| 272 | foreach my $cn (sort keys %cmap) {
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| 273 | my $targ = $cmap{$cn};
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| 274 | #print "dbg: ".Dumper($targ);
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| 275 | my @targlist;
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| 276 | # push @targlist, $targ; # mostly for error reporting
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| 277 | my $dangle = 0;
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| 278 |
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| 279 | my $depth = 1; # CNAME -> A
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| 280 |
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| 281 | # check this as a loop for consistent fail/break conditions. bonus: may allow user choice for CNAME depth?
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| 282 | for (; $dangle == 0; $depth++) {
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| 283 |
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| 284 | #print "d:$depth checking $cn -> $targ\n";
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| 285 | push @targlist, $targ;
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| 286 |
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| 287 | # Depth limit. If made user-selectable should arguably set a hard
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| 288 | # limit because deeply chained CNAMEs are Baaaaad, mmkaay?
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| 289 | if ($depth >= $maxdepth) {
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| 290 | warn "CNAMEs too deeply chained, skipping: $cn => ".join(' => ', @targlist)."\n";
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| 291 | last;
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| 292 | }
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| 293 |
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| 294 | # break if CNAME target is in the A record list
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| 295 | last if $amap{$targ};
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| 296 | if ($cmap{$targ}) {
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| 297 | # note the new target
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| 298 | my $tmpcn = $targ;
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| 299 | $targ = $cmap{$tmpcn};
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| 300 | #print " chaining $tmpcn to new $targ\n";
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| 301 | } else {
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| 302 | # target is either out of zone or doesn't exist
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| 303 | $dangle = 1;
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| 304 | last;
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| 305 | }
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| 306 |
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| 307 |
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| 308 | #warn "chained cname $cn => $targ\n";
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| 309 | # CNAME to another CNAME
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| 310 | #$tmpcn => $targ\n";
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| 311 |
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| 312 | # last if $dangle;
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| 313 |
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| 314 | # if (!$amap{$targ}) {
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| 315 | # if ($cmap{$targ}) {
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| 316 | # $tmpcn = $targ;
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| 317 | # $targ = $cmap{$tmpcn};
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| 318 | #push @targlist, $targ;
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| 319 | #warn " chain target $cn => ".join(' => ', @targlist).
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| 320 | # "\n";
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| 321 | # } else {
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| 322 | # warn "skipping dangling CNAME $cn => $targlist[0] => $targlist[1]\n";
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| 323 | # next;
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| 324 | # }
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| 325 | # }
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| 326 | # } else {
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| 327 | # # skip depth-3 (?) CNAMES; any such zone does not belong as a hosts file anyway
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| 328 | # warn "skipping dangling CNAME $cn => $targ\n";
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| 329 | # next;
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| 330 | # }
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| 331 | # }
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| 332 |
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| 333 |
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| 334 | } # CNAME recursion loop
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| 335 |
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| 336 | next if $dangle;
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| 337 |
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| 338 | #print " chain target $cn => ".join(' => ', @targlist)."\n";
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| 339 | if ($amap{$targ}) {
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| 340 | # absent any criteria, we use the first IP a name was associated with
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| 341 | my $targip = $amap{$targ}[0];
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| 342 | $namemap{$targip}{$cn}++;
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| 343 | } else {
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| 344 | }
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| 345 | } # each %cmap
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| 346 |
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| 347 | #print Dumper \%amap;
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| 348 | #foreach my $n (keys %amap) {
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| 349 | # foreach my $ip (keys %{$amap{$n}}) {
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| 350 | #print "$ip\t$n\n";
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| 351 | # push @{$namemap{$ip}}, $n unless grep $n, @{$namemap{$ip}};
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| 352 | # $namemap{$ip}{$n}++;
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| 353 | # }
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| 354 | #}
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| 355 |
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| 356 | #print Dumper \%namemap;
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| 357 | foreach my $ip (sort keys %namemap) {
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| 358 | print "$ip\t".join(' ', sort keys %{$namemap{$ip}})."\n";
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| 359 | }
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