[PATCH 6/6] remote: Don't attempt remote connection from libvirtd

[Peter Krempa]

When a hypervisor driver is not compiled in and a user enables the
monolithic libvirtd, they get the following misleading error:

  $ virsh -c qemu:///system
  error: failed to connect to the hypervisor
  error: Failed to connect socket to '/var/run/libvirt/virtqemud-sock': No such file or directory

The issue is that the daemon side of the remote driver can't find the
appropriate driver, but the remote driver always accepts everything and
thus attempts to delegate further, which in case of libvirtd makes no
sense.

Use the new flag VIR_CONNECT_NO_REMOTE and pass it from libvirtd to the
opening function to avoid delegation in this specific case. After this
patch the above attempt produces:

  $ virsh -c qemu:///system
  error: failed to connect to the hypervisor
  error: no connection driver available for qemu:///system

Discovered when investigating https://gitlab.com/libvirt/libvirt/-/issues/370

Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
 src/remote/remote_daemon_dispatch.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/remote/remote_daemon_dispatch.c b/src/remote/remote_daemon_dispatch.c
index 061e0f7811..d7c473d2a1 100644
--- a/src/remote/remote_daemon_dispatch.c
+++ b/src/remote/remote_daemon_dispatch.c
@@ -1798,6 +1798,14 @@ remoteOpenConn(const char *uri,
     if (*conn)
         return 0;

+#ifdef LIBVIRTD
+    /* When libvirtd is in use we need to avoid any further delegation of the
+     * connection, which can be attempted in cases when the appropriate
+     * connection driver was not compiled in. In such case a wrong error message
+     * would be reported. */
+    connectFlags |= VIR_CONNECT_NO_REMOTE;
+#endif /* LIBVIRTD */
+
     if (!uri) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("connection not open"));
         return -1;
-- 
2.37.1