X-Git-Url: https://git.distorted.org.uk/~mdw/secnet/blobdiff_plain/e61a41a48cdc15d9743731deed717961fdcf4da2..af7201526cf9637ca59c48f3844da165c51d71c0:/polypath-interface-monitor-linux

diff --git a/polypath-interface-monitor-linux b/polypath-interface-monitor-linux
index 1b02bfa..0393382 100755
--- a/polypath-interface-monitor-linux
+++ b/polypath-interface-monitor-linux
@@ -5,6 +5,13 @@ use IO::Handle;
 my $us = $0;
 $us =~ s{.*/}{};
 
+open DEBUG, ">/dev/null" or die $!;
+
+if (@ARGV && $ARGV[0] eq '-D') {
+    shift @ARGV;
+    open DEBUG, ">&STDERR" or die $!;
+}
+
 die "$us: no arguments permitted\n" if @ARGV;
 
 our ($monh,$monchild);
@@ -44,14 +51,29 @@ for (;;) {
 	    die "monitor failed\n" unless $got;
 	}
 	$_='r' foreach values %reported;
+	print DEBUG "#########################################\n";
 	foreach my $ip (qw(4 6)) {
+	    print DEBUG "###### $ip:\n";
 	    my $addrh = new IO::File;
 	    open $addrh, "-|", qw(ip -o), "-$ip", qw(addr show)
 		or die "spawn addr $ip show: $!\n";
 	    my $afstr = $ip==4 ? 'inet' : $ip==6 ? 'inet6' : die;
 	    while (<$addrh>) {
+		print DEBUG "#$_";
 		if (m{^\d+\:\s*(\S+)\s+$afstr\s+([0-9a-z.:]+)(?:/\d+)?\s}) {
+		    my $rhs=$'; #';
 		    my $outline = "$ip $1 $2";
+		    # "ip -o addr show" has a ridiculous output format.  In
+		    # particular, it mixes output keywords which introduce
+		    # values with ones which don't, and there seems to be
+		    # no way to tell without knowing all the possible
+		    # keywords.  We hope that before the \ there is nothing
+		    # which contains arbitrary text (specifically, which
+		    # might be `tentative' other than to specify IPv6
+		    # tentativeness).  We have to do this for IPv6 only
+		    # because in the IPv4 output, the interface name
+		    # appears here!
+		    next if $ip==6 && $rhs=~m{[^\\]* tentative\s};
 		    $reported{$outline} .= "y";
 		} else {
 		    chomp;