test(dhcp): cover the check of an external ISC server

A local dhcpd, and an external one without netboot=ipxe nodes, get no
check. An external dhcpd that returns the check host updates every
node, after one omshell run that creates the host, whose statement
tests every iPXE feature option, and one that reads it back and removes
it. The first run opens no host, and each run creates a host with its
own name and address.

A rejected statement, a run cut short or without a reply, a lost
connection and the host of another run leave the netboot=ipxe nodes
unchanged, and the error names the server and the nodes. The replies
are those of dhcpd 4.4.

xCAT-test/unit/dhcp_isc_external_ipxe_check.t

@@ -0,0 +1,106 @@
+#!/usr/bin/env perl
+# makedhcp does not write the configuration of an external dhcpd, and OMAPI removes a host before it
+# adds it again. Before it updates netboot=ipxe nodes there, makedhcp creates a host of its own whose
+# statement tests every iPXE feature option, reads it back in a second omshell run, and removes it.
+# Only that host, returned by the dhcpd, lets the update go ahead.
+use strict;
+use warnings;
+## no critic (TestingAndDebugging::ProhibitNoWarnings)
+no warnings 'once';
+
+use FindBin;
+use lib "$FindBin::Bin/../../xCAT-server/lib";
+use lib "$FindBin::Bin/../../xCAT-server/lib/perl";
+use lib "$FindBin::Bin/../../perl-xCAT";
+
+use Test::More;
+
+use xCAT::DHCP::OmapiPolicy;
+
+$ENV{XCATCFG} ||= 'SQLite:/tmp';
+my $source_dhcp_plugin = "$FindBin::Bin/../../xCAT-server/lib/xcat/plugins/dhcp.pm";
+if ( -f $source_dhcp_plugin ) {
+    require $source_dhcp_plugin;
+} else {
+    require xCAT_plugin::dhcp;
+}
+
+my $settings = xCAT::DHCP::OmapiPolicy->settings( site_values => {} );
+my %nrhash = (
+    'cn-ipxe' => [ { netboot => 'ipxe' } ],
+    'cn-xnba' => [ { netboot => 'xnba' } ],
+    'cn-none' => [ {} ],
+);
+# The replies of dhcpd 4.4 without the declarations (rejected) and with them (kept), for the host that
+# the first omshell run of the check creates.
+sub mac_of { my ($commands) = @_; return $commands =~ /^set hardware-address = (\S+)$/m ? $1 : ''; }
+my @rejected = ( "> can't open object: parse error(s) occurred\n", "obj: host\n", "hardware-type = 1\n" );
+my @not_found = ( "> can't open object: not found\n", "obj: host\n" );
+sub created { my ($mac) = @_; return ( "> obj: host\n", "hardware-address = $mac\n", "hardware-type = 00:00:00:01\n" ); }
+sub kept { my ($mac) = @_; return ( "> obj: host\n", "hardware-address = $mac\n", "hardware-type = 00:00:00:01\n", "> obj: <null>\n" ); }
+
+# Each reply is a list of lines or a code that gets the commands of the first run.
+my ( @commands, @replies );
+no warnings 'redefine';
+local *xCAT_plugin::dhcp::_run_omshell = sub {
+    push @commands, $_[0];
+    my $reply = shift(@replies) || [];
+    return ref($reply) eq 'CODE' ? $reply->( $commands[0] ) : @$reply;
+};
+
+sub check {
+    my ( $server, @nodes ) = @_;
+    local $::XCATSITEVALS{externaldhcpservers} = $server;
+    @commands = ();
+    return xCAT_plugin::dhcp::_isc_external_ipxe_check( \@nodes, \%nrhash, $settings, 'c2VjcmV0' );
+}
+my @accepts = ( sub { created( mac_of(shift) ) }, sub { kept( mac_of(shift) ) } );
+
+@replies = @accepts;
+my ( $unchanged, $error ) = check( undef, 'cn-ipxe' );
+is_deeply( [ $unchanged, $error, scalar @commands ], [ {}, undef, 0 ], 'a local dhcpd gets no check' );
+
+( $unchanged, $error ) = check( '192.0.2.53', 'cn-xnba', 'cn-none' );
+is_deeply( [ $unchanged, $error, scalar @commands ], [ {}, undef, 0 ], 'an external dhcpd gets no check without netboot=ipxe nodes' );
+
+@replies = @accepts;
+( $unchanged, $error ) = check( '192.0.2.53', 'cn-ipxe', 'cn-xnba' );
+is_deeply( [ $unchanged, $error ], [ {}, undef ], 'an external dhcpd that keeps the check host updates every node' );
+is( scalar @commands, 2, 'after one omshell run that creates the host and one that reads it back' );
+like( $commands[0], qr/^server 192\.0\.2\.53$/m, 'against the external dhcpd' );
+like( $commands[0],
+    qr/^set statements = "if exists gpxe\.iscsi and exists gpxe\.http and exists gpxe\.bzimage and exists gpxe\.pxe and exists gpxe\.efi \{ filename = \\"\\"; \}"\ncreate$/m,
+    'a host whose statement tests every iPXE feature option' );
+unlike( $commands[0], qr/^(?:open|remove)$/m, 'the first run opens no host before it creates one' );
+my ($name) = $commands[0] =~ /^set name = "(xcat-ipxe-check-[0-9a-f]+)"$/m;
+ok( $name, 'the check host has a name of its own' );
+like( mac_of( $commands[0] ), qr/^02(?::[0-9a-f]{2}){5}$/, 'and a locally administered address' );
+like( $commands[1], qr/^set name = "\Q$name\E"\nopen\nremove$/m, 'the second run reads that host back and removes it' );
+unlike( $commands[1], qr/^set hardware-address/m, 'setting only its name' );
+
+my @first = @commands;
+@replies = @accepts;
+check( '192.0.2.53', 'cn-ipxe' );
+isnt( mac_of( $commands[0] ), mac_of( $first[0] ), 'another run creates a host with another address' );
+
+@replies = ( [ @rejected ], [ @not_found ] );
+( $unchanged, $error ) = check( '192.0.2.53', 'cn-ipxe', 'cn-xnba' );
+is_deeply( $unchanged, { 'cn-ipxe' => 1 }, 'an external dhcpd without the options leaves the netboot=ipxe nodes unchanged' );
+like( $error, qr/^The DHCP server 192\.0\.2\.53 does not declare the iPXE feature options.*: cn-ipxe\. /,
+    'and makedhcp names the server and the nodes' );
+
+for my $case (
+    [ 'a first run cut short', [ [ "> obj: host\n" ], [@not_found] ] ],
+    [ 'a second run without a reply', [ $accepts[0], [] ] ],
+    [ 'a second run cut short', [ $accepts[0], [ "> obj: host\n" ] ] ],
+    [ 'a host of another run', [ $accepts[0], [ kept('02:00:00:00:00:01') ] ] ],
+    [ 'a lost connection', [ ["> not connected\n"], ["> not connected\n"] ] ],
+  )
+{
+    @replies = @{ $case->[1] };
+    ( $unchanged, $error ) = check( '192.0.2.53', 'cn-ipxe' );
+    is_deeply( $unchanged, { 'cn-ipxe' => 1 }, "$case->[0] leaves the netboot=ipxe nodes unchanged" );
+    like( $error, qr/did not confirm a check of the iPXE feature options/, "$case->[0] is reported" );
+}
+
+done_testing();