nbd: Keep hostname and port separate

The NBD block supports an URL syntax, for which a URL parser returns
separate hostname and port fields. It also supports the traditional qemu
syntax encoded in a filename. Until now, after parsing the URL to get
each piece of information, a new string is built to be fed to socket
functions.

Instead of building a string in the URL case that is immediately parsed
again, parse the string in both cases and use the QemuOpts interface to
qemu-sockets.c.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/nbd.c b/nbd.c
index 0698a02..97879ca 100644
--- a/nbd.c
+++ b/nbd.c
@@ -218,6 +218,18 @@
     return fd;
 }
 
+int tcp_socket_outgoing_opts(QemuOpts *opts)
+{
+    Error *local_err = NULL;
+    int fd = inet_connect_opts(opts, &local_err, NULL, NULL);
+    if (local_err != NULL) {
+        qerror_report_err(local_err);
+        error_free(local_err);
+    }
+
+    return fd;
+}
+
 int tcp_socket_incoming(const char *address, uint16_t port)
 {
     char address_and_port[128];