rpc: add method for checking if a named server exists

It is not possible to blindly call virNetDaemonGetServer()
because in a post-exec restart scenario, some servers may
not exist and this method will pollute the error logs.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/libvirt_remote.syms

@@ -69,6 +69,7 @@ virNetDaemonClose;
 virNetDaemonGetServer;
 virNetDaemonGetServers;
 virNetDaemonHasClients;
+virNetDaemonHasServer;
 virNetDaemonIsPrivileged;
 virNetDaemonNew;
 virNetDaemonNewPostExecRestart;

src/rpc/virnetdaemon.c

@@ -195,6 +195,19 @@ virNetDaemonGetServer(virNetDaemonPtr dmn,
     return srv;
 }
 
+bool
+virNetDaemonHasServer(virNetDaemonPtr dmn,
+                      const char *serverName)
+{
+    void *ent;
+
+    virObjectLock(dmn);
+    ent = virHashLookup(dmn->servers, serverName);
+    virObjectUnlock(dmn);
+
+    return ent != NULL;
+}
+
 
 struct collectData {
     virNetServerPtr **servers;

src/rpc/virnetdaemon.h

@@ -83,5 +83,7 @@ bool virNetDaemonHasClients(virNetDaemonPtr dmn);
 virNetServerPtr virNetDaemonGetServer(virNetDaemonPtr dmn,
                                       const char *serverName);
 ssize_t virNetDaemonGetServers(virNetDaemonPtr dmn, virNetServerPtr **servers);
+bool virNetDaemonHasServer(virNetDaemonPtr dmn,
+                           const char *serverName);
 
 #endif /* __VIR_NET_DAEMON_H__ */