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Avoid picking already-bound TCP ports in kerberos and ldap test suites.

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src/test/kerberos and src/test/ldap need to run a private authentication
server of the relevant type, for which they need a free TCP port.
They were just picking a random port number in 48K-64K, which works
except when something's already using the particular port.  Notably,
the probability of failure rises dramatically if one simply runs those
tests in a tight loop, because each test cycle leaves behind a bunch of
high ports that are transiently in TIME_WAIT state.

To fix, split out the code that PostgresNode.pm already had for
identifying a free TCP port number, so that it can be invoked to choose
a port for the KDC or LDAP server.  This isn't 100% bulletproof, since
conceivably something else on the machine could grab the port between
the time we check and the time we actually start the server.  But that's
a pretty short window, so in practice this should be good enough.

Back-patch to v11 where these test suites were added.

Patch by me, reviewed by Andrew Dunstan.

Discussion: https://postgr.es/m/3397.1564872168@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2019-08-04 13:07:12 -04:00
parent e3967a16d3
commit 45d6789e78
3 changed files with 88 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/test/kerberos/t/001_auth.pl
View File

@ -56,7 +56,7 @@ my $krb5_conf = "${TestLib::tmp_check}/krb5.conf";
my $kdc_conf = "${TestLib::tmp_check}/kdc.conf";
my $krb5_log = "${TestLib::tmp_check}/krb5libs.log";
my $kdc_log = "${TestLib::tmp_check}/krb5kdc.log";
my $kdc_port = int(rand() * 16384) + 49152;
my $kdc_port = get_free_port();
my $kdc_datadir = "${TestLib::tmp_check}/krb5kdc";
my $kdc_pidfile = "${TestLib::tmp_check}/krb5kdc.pid";
my $keytab = "${TestLib::tmp_check}/krb5.keytab";

2
src/test/ldap/t/001_auth.pl
View File

@ -48,7 +48,7 @@ my $slapd_pidfile = "${TestLib::tmp_check}/slapd.pid";
my $slapd_logfile = "${TestLib::tmp_check}/slapd.log";
my $ldap_conf = "${TestLib::tmp_check}/ldap.conf";
my $ldap_server = 'localhost';
my $ldap_port = int(rand() * 16384) + 49152;
my $ldap_port = get_free_port();
my $ldaps_port = $ldap_port + 1;
my $ldap_url = "ldap://$ldap_server:$ldap_port";
my $ldaps_url = "ldaps://$ldap_server:$ldaps_port";

134
src/test/perl/PostgresNode.pm
View File

@ -63,6 +63,9 @@ PostgresNode - class representing PostgreSQL server instance
# Stop the server
$node->stop('fast');
# Find a free, unprivileged TCP port to bind some other service to
my $port = get_free_port();
=head1 DESCRIPTION
PostgresNode contains a set of routines able to work on a PostgreSQL node,
@ -102,6 +105,7 @@ use Scalar::Util qw(blessed);
our @EXPORT = qw(
get_new_node
get_free_port
);
our ($use_tcp, $test_localhost, $test_pghost, $last_host_assigned,
@ -1022,54 +1026,21 @@ sub get_new_node
my $class = 'PostgresNode';
$class = shift if scalar(@_) % 2 != 1;
my ($name, %params) = @_;
my $port_is_forced = defined $params{port};
my $found = $port_is_forced;
my $port = $port_is_forced ? $params{port} : $last_port_assigned;
while ($found == 0)
# Select a port.
my $port;
if (defined $params{port})
{
# advance $port, wrapping correctly around range end
$port = 49152 if ++$port >= 65536;
print "# Checking port $port\n";
# Check first that candidate port number is not included in
# the list of already-registered nodes.
$found = 1;
foreach my $node (@all_nodes)
{
$found = 0 if ($node->port == $port);
}
# Check to see if anything else is listening on this TCP port. This
# is *necessary* on $use_tcp (Windows) configurations. Seek a port
# available for all possible listen_addresses values, for own_host
# nodes and so the caller can harness this port for the widest range
# of purposes. The 0.0.0.0 test achieves that for post-2006 Cygwin,
# which automatically sets SO_EXCLUSIVEADDRUSE. The same holds for
# MSYS (a Cygwin fork). Testing 0.0.0.0 is insufficient for Windows
# native Perl (https://stackoverflow.com/a/14388707), so we also test
# individual addresses.
#
# This seems like a good idea on Unixen as well, even though we don't
# ask the postmaster to open a TCP port on Unix. On Non-Linux,
# non-Windows kernels, binding to 127.0.0.1/24 addresses other than
# 127.0.0.1 might fail with EADDRNOTAVAIL. Binding to 0.0.0.0 is
# unnecessary on non-Windows systems.
#
# XXX A port available now may become unavailable by the time we start
# the postmaster.
if ($found == 1)
{
foreach my $addr (qw(127.0.0.1),
$use_tcp ? qw(127.0.0.2 127.0.0.3 0.0.0.0) : ())
{
can_bind($addr, $port) or $found = 0;
}
}
$port = $params{port};
}
else
{
# When selecting a port, we look for an unassigned TCP port number,
# even if we intend to use only Unix-domain sockets. This is clearly
# necessary on $use_tcp (Windows) configurations, and it seems like a
# good idea on Unixen as well.
$port = get_free_port();
}
print "# Found port $port\n";
# Select a host.
my $host = $test_pghost;
@ -1094,12 +1065,79 @@ sub get_new_node
# Add node to list of nodes
push(@all_nodes, $node);
# And update port for next time
$port_is_forced or $last_port_assigned = $port;
return $node;
}
=pod
=item get_free_port()
Locate an unprivileged (high) TCP port that's not currently bound to
anything. This is used by get_new_node, and is also exported for use
by test cases that need to start other, non-Postgres servers.
Ports assigned to existing PostgresNode objects are automatically
excluded, even if those servers are not currently running.
XXX A port available now may become unavailable by the time we start
the desired service.
=cut
sub get_free_port
{
my $found = 0;
my $port = $last_port_assigned;
while ($found == 0)
{
# advance $port, wrapping correctly around range end
$port = 49152 if ++$port >= 65536;
print "# Checking port $port\n";
# Check first that candidate port number is not included in
# the list of already-registered nodes.
$found = 1;
foreach my $node (@all_nodes)
{
$found = 0 if ($node->port == $port);
}
# Check to see if anything else is listening on this TCP port.
# Seek a port available for all possible listen_addresses values,
# so callers can harness this port for the widest range of purposes.
# The 0.0.0.0 test achieves that for post-2006 Cygwin, which
# automatically sets SO_EXCLUSIVEADDRUSE. The same holds for MSYS (a
# Cygwin fork). Testing 0.0.0.0 is insufficient for Windows native
# Perl (https://stackoverflow.com/a/14388707), so we also test
# individual addresses.
#
# On non-Linux, non-Windows kernels, binding to 127.0.0/24 addresses
# other than 127.0.0.1 might fail with EADDRNOTAVAIL. Binding to
# 0.0.0.0 is unnecessary on non-Windows systems.
if ($found == 1)
{
foreach my $addr (qw(127.0.0.1),
$use_tcp ? qw(127.0.0.2 127.0.0.3 0.0.0.0) : ())
{
if (!can_bind($addr, $port))
{
$found = 0;
last;
}
}
}
}
print "# Found port $port\n";
# Update port for next time
$last_port_assigned = $port;
return $port;
}
# Internal routine to check whether a host:port is available to bind
sub can_bind
{