[pve-devel] [PATCH qemu-server 1/4] parse nbd_protocol_version if available

[Mira Limbeck]

For secure live migration with local disks via NBD over a unix socket,
we have to somehow communicate support for it from the source node to the
target node. This is because there can only be one NBD server with either a TCP
or Unix socket bound, not both.

The source node passes that information via STDIN after the spice
ticket followed by a newline for backwards compatibility. If there is no
spice ticket we just pass the newline followed by the
'nbd_protocol_version: <version>' line.

For unix socket support we parse the line 'nbd_protocol_version:
<version>'. A version >= 1 means unix socket support. We use a fallback
to 0 should there be no line containing that pattern which is the case
if the source node has an older qemu-server version.

Signed-off-by: Mira Limbeck <m.limbeck at proxmox.com>
---
 PVE/API2/Qemu.pm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/PVE/API2/Qemu.pm b/PVE/API2/Qemu.pm
index 3b61334..8891db9 100644
--- a/PVE/API2/Qemu.pm
+++ b/PVE/API2/Qemu.pm
@@ -2035,10 +2035,17 @@ __PACKAGE__->register_method({
 
 	# read spice ticket from STDIN
 	my $spice_ticket;
+	my $nbd_protocol_version = 0;
 	if ($stateuri && ($stateuri eq 'tcp' || $stateuri eq 'unix') && $migratedfrom && ($rpcenv->{type} eq 'cli')) {
 	    if (defined(my $line = <STDIN>)) {
 		chomp $line;
 		$spice_ticket = $line;
+		while (defined(my $line = <STDIN>)) {
+		    chomp $line;
+		    if ($line =~ m/^nbd_protocol_version: (\d+)$/) {
+			$nbd_protocol_version = $1;
+		    }
+		}
 	    }
 	}
 
@@ -2067,7 +2074,8 @@ __PACKAGE__->register_method({
 		syslog('info', "start VM $vmid: $upid\n");
 
 		PVE::QemuServer::vm_start($storecfg, $vmid, $stateuri, $skiplock, $migratedfrom, undef, $machine,
-					  $spice_ticket, $migration_network, $migration_type, $targetstorage, $timeout);
+					  $spice_ticket, $migration_network, $migration_type, $targetstorage, $timeout,
+					  $nbd_protocol_version);
 		return;
 	    };
 
-- 
2.20.1