[3.13] gh-142991: socketmodule: fixed getsockaddrlen() for PF_DIVERT socket (GH-142993) (#143482)

gh-142991: socketmodule: fixed getsockaddrlen() for PF_DIVERT socket (GH-142993)
(cherry picked from commit 05406b2)

Co-authored-by: Gleb Smirnoff <glebius@FreeBSD.org>

Author: miss-islington

Misc/NEWS.d/next/Library/2025-12-20-10-21-23.gh-issue-142991.jYHD9E.rst

@@ -0,0 +1,2 @@
+Fixed socket operations such as recvfrom() and sendto() for FreeBSD
+divert(4) socket.

Modules/socketmodule.c

@@ -2649,6 +2649,12 @@ getsockaddrlen(PySocketSockObject *s, socklen_t *len_ret)
         /* RDS sockets use sockaddr_in: fall-through */
 #endif /* AF_RDS */
 
+#ifdef AF_DIVERT
+    case AF_DIVERT:
+        /* FreeBSD divert(4) sockets use sockaddr_in: fall-through */
+       _Py_FALLTHROUGH;
+#endif /* AF_DIVERT */
+
     case AF_INET:
     {
         *len_ret = sizeof (struct sockaddr_in);