mdw@git.distorted.org.uk Git - secnet/blob - polypath-interface-monitor-linux

   1 #!/usr/bin/perl -w
   2 use strict;
   3 use IO::Handle;
   4
   5 my $us = $0;
   6 $us =~ s{.*/}{};
   7
   8 die "$us: no arguments permitted\n" if @ARGV;
   9
  10 our ($monh,$monchild);
  11
  12 our %reported;
  13 #  no entry: not reported, does not exist
  14 #  /ry+/: reported, entry exists
  15 # during processing only:
  16 #  /r/: reported, may not still exist
  17 #  /y+/: not reported, entry exists
  18
  19 sub killmonitor () {
  20     return unless $monchild;
  21     kill 9, $monchild
  22         or warn "$us: cannot kill monitor child [$monchild]: $!\n";
  23     $monchild=undef;
  24     close $monh;
  25 }
  26
  27 END { killmonitor(); }
  28
  29 my $restart;
  30
  31 for (;;) {
  32     my $o;
  33     eval {
  34         if (!$monh) {
  35             killmonitor();
  36             $monh = new IO::File;
  37             $monchild = open $monh, "-|", qw(ip -o monitor addr)
  38                 or die "spawn monitor: $!\n";
  39             sleep(1) if $restart++;
  40         } else {
  41             my $discard;
  42             my $got = sysread $monh, $discard, 4096;
  43             die "read monitor: $!\n" unless defined $got;
  44             die "monitor failed\n" unless $got;
  45         }
  46         $_='r' foreach values %reported;
  47         foreach my $ip (qw(4 6)) {
  48             my $addrh = new IO::File;
  49             open $addrh, "-|", qw(ip -o), "-$ip", qw(addr show)
  50                 or die "spawn addr $ip show: $!\n";
  51             my $afstr = $ip==4 ? 'inet' : $ip==6 ? 'inet6' : die;
  52             while (<$addrh>) {
  53                 if (m{^\d+\:\s*(\S+)\s+$afstr\s+([0-9a-z.:]+)(?:/\d+)?\s}) {
  54                     my $outline = "$ip $1 $2";
  55                     $reported{$outline} .= "y";
  56                 } else {
  57                     chomp;
  58                     warn "unexpected output from addr $ip show: $_\n";
  59                 }
  60             }
  61             my $r = close $addrh;
  62             die "addr $ip show failed $!\n" unless $r;
  63             $o = '';
  64         }
  65         foreach my $k (keys %reported) {
  66             local $_ = $reported{$k};
  67             if (m/^r$/) {
  68                 $o .= "-$k\n";
  69                 delete $reported{$k};
  70             } elsif (m/^y/) {
  71                 $o .= "+$k\n";
  72             }
  73         }
  74     };
  75     if ($@) {
  76         print STDERR "$us: $@";
  77         sleep 5;
  78         next;
  79     }
  80     print $o or die $!;
  81     STDOUT->flush or die $!;
  82 }