char: refactor parsing of socket address information

To prepare for handling more address types, refactor the parsing of
socket address information to make it more robust and extensible.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 1a371b9..a916ef4 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -1012,21 +1012,25 @@
     SocketAddressLegacy *addr;
     ChardevSocket *sock;
 
+    if ((!!path + !!host) != 1) {
+        error_setg(errp,
+                   "Exactly one of 'path' or 'host' required");
+        return;
+    }
+
     backend->type = CHARDEV_BACKEND_KIND_SOCKET;
-    if (!path) {
-        if (!host) {
-            error_setg(errp, "chardev: socket: no host given");
+    if (path) {
+        if (tls_creds) {
+            error_setg(errp, "TLS can only be used over TCP socket");
             return;
         }
+    } else if (host) {
         if (!port) {
             error_setg(errp, "chardev: socket: no port given");
             return;
         }
     } else {
-        if (tls_creds) {
-            error_setg(errp, "TLS can only be used over TCP socket");
-            return;
-        }
+        g_assert_not_reached();
     }
 
     sock = backend->u.socket.data = g_new0(ChardevSocket, 1);
@@ -1052,7 +1056,7 @@
         addr->type = SOCKET_ADDRESS_LEGACY_KIND_UNIX;
         q_unix = addr->u.q_unix.data = g_new0(UnixSocketAddress, 1);
         q_unix->path = g_strdup(path);
-    } else {
+    } else if (host) {
         addr->type = SOCKET_ADDRESS_LEGACY_KIND_INET;
         addr->u.inet.data = g_new(InetSocketAddress, 1);
         *addr->u.inet.data = (InetSocketAddress) {
@@ -1065,6 +1069,8 @@
             .has_ipv6 = qemu_opt_get(opts, "ipv6"),
             .ipv6 = qemu_opt_get_bool(opts, "ipv6", 0),
         };
+    } else {
+        g_assert_not_reached();
     }
     sock->addr = addr;
 }