tree-wide: introduce new SOCKADDR_UN_LEN() macro, and use it everywhere

The macro determines the right length of a AF_UNIX "struct sockaddr_un" to pass to
connect() or bind(). It automatically figures out if the socket refers to an
abstract namespace socket, or a socket in the file system, and properly handles
the full length of the path field.

This macro is not only safer, but also simpler to use, than the usual
offsetof() + strlen() logic.

1 files changed, 4 insertions, 13 deletions

diff --git a/src/socket-proxy/socket-proxyd.c b/src/socket-proxy/socket-proxyd.c
index 1157a0c72e..52b4db8875 100644
--- a/src/socket-proxy/socket-proxyd.c
+++ b/src/socket-proxy/socket-proxyd.c
@@ -400,28 +400,19 @@ static int resolve_remote(Connection *c) {
 
         union sockaddr_union sa = {};
         const char *node, *service;
-        socklen_t salen;
         int r;
 
         if (path_is_absolute(arg_remote_host)) {
                 sa.un.sun_family = AF_UNIX;
-                strncpy(sa.un.sun_path, arg_remote_host, sizeof(sa.un.sun_path)-1);
-                sa.un.sun_path[sizeof(sa.un.sun_path)-1] = 0;
-
-                salen = offsetof(union sockaddr_union, un.sun_path) + strlen(sa.un.sun_path);
-
-                return connection_start(c, &sa.sa, salen);
+                strncpy(sa.un.sun_path, arg_remote_host, sizeof(sa.un.sun_path));
+                return connection_start(c, &sa.sa, SOCKADDR_UN_LEN(sa.un));
         }
 
         if (arg_remote_host[0] == '@') {
                 sa.un.sun_family = AF_UNIX;
                 sa.un.sun_path[0] = 0;
-                strncpy(sa.un.sun_path+1, arg_remote_host+1, sizeof(sa.un.sun_path)-2);
-                sa.un.sun_path[sizeof(sa.un.sun_path)-1] = 0;
-
-                salen = offsetof(union sockaddr_union, un.sun_path) + 1 + strlen(sa.un.sun_path + 1);
-
-                return connection_start(c, &sa.sa, salen);
+                strncpy(sa.un.sun_path+1, arg_remote_host+1, sizeof(sa.un.sun_path)-1);
+                return connection_start(c, &sa.sa, SOCKADDR_UN_LEN(sa.un));
         }
 
         service = strrchr(arg_remote_host, ':');