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test(xCAT-test): cover the detect_dhcpd capture lifecycle

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Inside the private network namespace the fake tcpdump records its parent,
its output file and the TERM it receives, ps records any use, and a second
fake tcpdump fails at once. Both copies must start tcpdump directly, write
under TMPDIR, stop it by pid, leave no file behind, and exit 1 when the
capture fails. The block skips where no namespace is available.

Signed-off-by: Vinícius Ferrão <2031761+viniciusferrao@users.noreply.github.com>
This commit is contained in:
Vinícius Ferrão
2026-09-10 02:10:25 -03:00
parent 955713c4b2
commit b8ab7be46e
1 changed files with 134 additions and 2 deletions
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xCAT-test/unit/detect_dhcpd_tcpdump_lookup.t
+134 -2
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@@ -52,8 +52,8 @@ my $marker = File::Spec->catfile( tempdir( @fixture_dir, CLEANUP => 1 ), 'tcpdum
sub fixture_bin {
my (%with) = @_;
my $bindir = tempdir( @fixture_dir, CLEANUP => 1 );
write_script( "$bindir/tcpdump", qq{printf '%s\\n' "\$0" "\$*" > '$marker'\nexit 0\n} );
foreach my $tool (qw(awk head grep ps)) {
write_script( "$bindir/tcpdump", qq{printf '%s\\n' "\$0" "\$*" > '$marker'\ntrap 'exit 0' TERM\nwhile :; do sleep 1; done\n} );
foreach my $tool (qw(awk head grep ps sleep)) {
my $real = xCAT::CommandUtils::find_executable($tool) or next;
symlink( $real, "$bindir/$tool" ) or die "symlink $tool: $!";
}
@@ -142,4 +142,136 @@ SKIP: {
is( $args, "-i lo port 68 -n -vvvvvv", '... with the capture arguments' );
}
# ---- capture lifecycle: a private dump file, tcpdump run directly and stopped by pid ------------
# Both copies wrote /tmp/dhcpdumpfile.log, ran tcpdump behind a shell, killed every tcpdump on the
# interface by pattern, and reported zero servers when tcpdump failed to start. The fake tcpdump
# below records who started it and where its output goes, waits for the TERM the script owes it,
# and a second one fails at once. ps records any use, since the scripts no longer need it.
sub lifecycle_bin {
my (%with) = @_;
my $bindir = tempdir( @fixture_dir, CLEANUP => 1 );
my $record = "$with{record}";
if ( $with{fail} ) {
write_script( "$bindir/tcpdump", qq{printf 'started\\n' >> '$record'\nexit 1\n} );
} elsif ( $with{quit} ) {
write_script( "$bindir/tcpdump", qq{printf 'started\\n' >> '$record'\nexit 0\n} );
} elsif ( $with{killed} ) {
write_script( "$bindir/tcpdump", qq{printf 'started\\n' >> '$record'\nkill -9 \$\$\n} );
} elsif ( $with{stubborn} ) {
write_script( "$bindir/tcpdump", qq{trap '' TERM\nprintf 'started\\n' >> '$record'\nwhile :; do sleep 1; done\n} );
} else {
write_script( "$bindir/tcpdump",
qq{parent=\$(cat /proc/\$PPID/comm 2>/dev/null)\n}
. qq{out=\$(readlink /proc/\$\$/fd/1 2>/dev/null)\n}
. qq{printf 'pid=%s ppid=%s parent=%s out=%s\\n' "\$\$" "\$PPID" "\$parent" "\$out" >> '$record'\n}
. qq{trap 'printf "TERM\\n" >> "$record"; exit 0' TERM\n}
. qq{while :; do sleep 1; done\n} );
}
write_script( "$bindir/ps", qq{printf 'ps %s\\n' "\$*" >> '$record.ps'\nexit 0\n} );
foreach my $tool (qw(awk head grep cat readlink sleep)) {
my $real = xCAT::CommandUtils::find_executable($tool) or next;
symlink( $real, "$bindir/$tool" ) or die "symlink $tool: $!";
}
symlink( $with{real_ip}, "$bindir/ip" ) or die "symlink ip: $!";
return $bindir;
}
sub run_isolated_status {
my ( $ns, $bindir, $tmpdir, $script, @args ) = @_;
my $command = "env PATH='$bindir' XCATROOT='$root' TMPDIR='$tmpdir' " . script_command( $script, @args );
my $shell = "$ns->{unshare} $ns->{flags} sh -c \"$ns->{setup} && exec $command\" 2>&1";
my $out = `$shell`;
return ( $out, $? >> 8 );
}
sub slurp_lines {
my ($path) = @_;
open( my $fh, '<', $path ) or return;
chomp( my @lines = <$fh> );
close($fh);
return @lines;
}
SKIP: {
skip 'the private /tmp would hide this checkout or its fixtures', 44
if index( $repo, '/tmp/' ) == 0 || !@fixture_dir;
my $ns = isolation();
skip 'no private network namespace on this host', 44 unless $ns;
foreach my $case ( [ $tools, 'the tool', '-t' ], [ $probe, 'the probe', '-d' ] ) {
my ( $script, $label, $window ) = @$case;
my $tmpdir = tempdir( @fixture_dir, CLEANUP => 1 );
my $record = File::Spec->catfile( tempdir( @fixture_dir, CLEANUP => 1 ), 'tcpdump.record' );
my $bindir = lifecycle_bin( record => $record, real_ip => $ns->{ip} );
my ( $out, $status ) = run_isolated_status( $ns, $bindir, $tmpdir, $script, '-i', 'lo', '-m', $mac, $window, '1' );
is( $status, 0, "$label exits 0 after a capture window" );
my @rec = slurp_lines($record);
my ($start) = grep { /^pid=/ } @rec;
ok( defined $start, "$label started tcpdump" ) or diag($out);
like( $start // '', qr/ parent=perl /, '... directly from the script, with no shell in between' );
like( $start // '', qr{ out=\Q$tmpdir\E/detect_dhcpd\.\w+$}, '... writing a private capture file under TMPDIR' );
ok( ( grep { $_ eq 'TERM' } @rec ), '... and stopped it with TERM when the window ended' );
ok( !-e "$record.ps", '... without searching the process table' );
my @left = glob("$tmpdir/detect_dhcpd.*");
is( scalar(@left), 0, '... and removed the capture file on exit' );
my $failing = lifecycle_bin( record => $record, real_ip => $ns->{ip}, fail => 1 );
( $out, $status ) = run_isolated_status( $ns, $failing, $tmpdir, $script, '-i', 'lo', '-m', $mac, $window, '1' );
is( $status, 1, "$label exits 1 when tcpdump fails to start" ) or diag($out);
like( $out, qr/tcpdump ended before the capture window did, with status 1|Capture the packets by tcpdump/, '... and says the capture failed' );
unlike( $out, qr/0 servers repl/, '... instead of reporting zero servers' );
@left = glob("$tmpdir/detect_dhcpd.*");
is( scalar(@left), 0, '... and leaves no capture file behind' );
my $quitting = lifecycle_bin( record => $record, real_ip => $ns->{ip}, quit => 1 );
( $out, $status ) = run_isolated_status( $ns, $quitting, $tmpdir, $script, '-i', 'lo', '-m', $mac, $window, '1' );
is( $status, 1, "$label exits 1 when tcpdump quits early with status 0" ) or diag($out);
unlike( $out, qr/0 servers repl/, '... instead of reporting zero servers' );
my $dying = lifecycle_bin( record => $record, real_ip => $ns->{ip}, killed => 1 );
( $out, $status ) = run_isolated_status( $ns, $dying, $tmpdir, $script, '-i', 'lo', '-m', $mac, $window, '1' );
is( $status, 1, "$label exits 1 when tcpdump dies on another signal" ) or diag($out);
like( $out, qr/on signal 9|Capture the packets by tcpdump/, '... and names the signal or the failed step' );
my $stubborn = lifecycle_bin( record => $record, real_ip => $ns->{ip}, stubborn => 1 );
my $began = time;
( $out, $status ) = run_isolated_status( $ns, $stubborn, $tmpdir, $script, '-i', 'lo', '-m', $mac, $window, '1' );
is( $status, 1, "$label exits 1 when tcpdump ignores TERM" ) or diag($out);
cmp_ok( time - $began, '<', 20, '... after a bounded grace period' );
like( $out, qr/on signal 9|Capture the packets by tcpdump/, '... having killed it' );
# An interrupt while the capture runs: the script is signalled once the fake tcpdump has
# reported the script's pid, and must stop tcpdump and remove the file on its way out.
my $int_record = File::Spec->catfile( tempdir( @fixture_dir, CLEANUP => 1 ), 'tcpdump.record' );
my $int_bin = lifecycle_bin( record => $int_record, real_ip => $ns->{ip} );
my $runner = fork;
die "fork: $!" unless defined $runner;
if ( $runner == 0 ) {
my ( undef, $st ) = run_isolated_status( $ns, $int_bin, $tmpdir, $script, '-i', 'lo', '-m', $mac, $window, '30' );
exit $st;
}
my $started;
foreach ( 1 .. 150 ) {
($started) = grep { /^pid=/ } slurp_lines($int_record);
last if $started;
select( undef, undef, undef, 0.2 );
}
my ($tcpdump_pid) = ( $started // '' ) =~ /^pid=(\d+)/;
my ($script_pid) = ( $started // '' ) =~ / ppid=(\d+)/;
ok( $script_pid, "$label reports the pid to interrupt" ) or diag( $started // 'tcpdump never started' );
if ($script_pid) {
kill 'INT', $script_pid;
select( undef, undef, undef, 0.3 );
kill 'INT', $script_pid;
}
waitpid( $runner, 0 );
is( $? >> 8, 1, '... and exits 1 on a double interrupt during the capture' );
ok( ( grep { $_ eq 'TERM' } slurp_lines($int_record) ), '... after stopping tcpdump' );
ok( !( $tcpdump_pid && kill( 0, $tcpdump_pid ) ), '... which is gone' );
@left = glob("$tmpdir/detect_dhcpd.*");
is( scalar(@left), 0, '... and the capture file is removed' );
}
}
done_testing();