gh-132991: Add socket.IP_FREEBIND constant (GH-132998)

Author: alyssais

Doc/library/socket.rst

@@ -476,8 +476,8 @@ Constants
       network interface instead of its name.
 
    .. versionchanged:: 3.14
-      Added missing ``IP_RECVERR``, ``IPV6_RECVERR``, ``IP_RECVTTL``, and
-      ``IP_RECVORIGDSTADDR`` on Linux.
+      Added missing ``IP_FREEBIND``, ``IP_RECVERR``, ``IPV6_RECVERR``,
+      ``IP_RECVTTL``, and ``IP_RECVORIGDSTADDR`` on Linux.
 
    .. versionchanged:: 3.14
       Added support for ``TCP_QUICKACK`` on Windows platforms when available.

Misc/NEWS.d/next/Library/2025-04-26-10-57-15.gh-issue-132991.ekkqdt.rst

@@ -0,0 +1 @@
+Add :data:`!socket.IP_FREEBIND` constant on Linux 2.4 and later.

Modules/socketmodule.c

@@ -8829,6 +8829,9 @@ socket_exec(PyObject *m)
 #ifdef  IP_MAX_MEMBERSHIPS
     ADD_INT_MACRO(m, IP_MAX_MEMBERSHIPS);
 #endif
+#ifdef  IP_FREEBIND
+    ADD_INT_MACRO(m, IP_FREEBIND);
+#endif
 #ifdef  IP_TRANSPARENT
     ADD_INT_MACRO(m, IP_TRANSPARENT);
 #endif