socket.AF_VSOCK is not defined

[bluecmd]

Hi,

Problem

bluecmd@fedora:~/Downloads$ tar -xf cpython-3.14.3+20260320-x86_64_v3-unknown-linux-gnu-install_only.tar.gz
bluecmd@fedora:~/Downloads$ ./python/bin/python
Python 3.14.3 (main, Mar 20 2026, 00:35:02) [Clang 22.1.1 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket
>>> socket.AF_VSOCK
Traceback (most recent call last):
  File "<python-input-1>", line 1, in <module>
    socket.AF_VSOCK
AttributeError: module 'socket' has no attribute 'AF_VSOCK'
>>> exit

Expected output

bluecmd@fedora:~/Downloads$ python
Python 3.14.3 (main, Feb  4 2026, 00:00:00) [GCC 15.2.1 20260123 (Red Hat 15.2.1-7)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket
>>> socket.AF_VSOCK
<AddressFamily.AF_VSOCK: 40>

Investigation

Probably caused by the build environment not having AF_VSOCK available in header files. In my system it is defined in /usr/include/bits/socket.h

[jjhelmus]

This is puzzling. AF_VSOCK is define in /usr/include/x86_64-linux-gnu/bits/socket.h which should be included from /usr/include/x86_64-linux-gnu/sys/socket.h. Both of these are from glibc and included in the Debian 8 (Jessie) build container that is used to build the x86-64 pbs distributions.

In a recent build log this directory is in the search path:

clang -pthread  -fno-strict-overflow -Wsign-compare -Wunreachable-code -DNDEBUG -g -O3 -Wall -I/usr/include/x86_64-linux-gnu   -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden  -I./Include/internal -I./Include/internal/mimalloc  -I. -I./Include -I/usr/include/x86_64-linux-gnu   -fPIC -c ./Modules/socketmodule.c -o Modules/socketmodule.o

[jjhelmus]

Ok, the issue is that sockets.AF_VSOCK requires linux/vm_sockets.h to be available, CPython gates the attribute based on availability.

This header was not included in the Linux UAPI headers until Linux 3.19 (although in should have been in earlier, see https://lists.openwall.net/netdev/2014/12/01/2).

Debian 8 (Jessie) includes the Linux 3.16 Linux UAPI headers where this file is not included.