[uri] Fix NULL dereference in parse_uri()

Don't try to parse authority if it's not there.

Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/uri.c

 	struct uri *uri;
 	char *raw;
 	char *tmp;
-	char *path = NULL;
-	char *authority = NULL;
+	char *path;
+	char *authority;
 	int i;
 	size_t raw_len;
 
 		} else {
 			/* Absolute URI with opaque part */
 			uri->opaque = tmp;
+			path = NULL;
 		}
 	} else {
 		/* Relative URI */
 	} else {
 		/* Absolute/relative path */
 		uri->path = path;
+		authority = NULL;
 	}
 
+	/* If we don't have an authority (i.e. we have a non-net
+	 * path), we're already finished processing
+	 */
+	if ( ! authority )
+		goto done;
+
 	/* Split authority into user[:password] and host[:port] portions */
 	if ( ( tmp = strchr ( authority, '@' ) ) ) {
 		/* Has user[:password] */