socket module missing IPPROTO_IPV6, IPPROTO_IPV4 on Windows

[mhils]

BPO	29515
Nosy	@pfmoore, @jaraco, @giampaolo, @tiran, @tjguk, @zware, @eryksun, @zooba, @mhils, @abrezovsky
PRs	bpo-29515: add missing socket.IPPROTO_* constants on Windows #12183
Dependencies	bpo-17561: Add socket.bind_socket() convenience function

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-02-13.03:53:58.390>
created_at = <Date 2017-02-09.18:27:42.493>
labels = ['easy', 'type-bug', '3.8', 'OS-windows']
title = 'socket module missing IPPROTO_IPV6, IPPROTO_IPV4 on Windows'
updated_at = <Date 2021-02-13.03:53:58.389>
user = 'https://github.com/mhils'

bugs.python.org fields:

activity = <Date 2021-02-13.03:53:58.389>
actor = 'jaraco'
assignee = 'none'
closed = True
closed_date = <Date 2021-02-13.03:53:58.390>
closer = 'jaraco'
components = ['Windows']
creation = <Date 2017-02-09.18:27:42.493>
creator = 'mhils'
dependencies = ['17561']
files = []
hgrepos = []
issue_num = 29515
keywords = ['patch', 'easy (C)']
message_count = 19.0
messages = ['287449', '287472', '287477', '287541', '333133', '333727', '335924', '335929', '337194', '337229', '337240', '337242', '337251', '337269', '337273', '338230', '339047', '339048', '386899']
nosy_count = 11.0
nosy_names = ['paul.moore', 'jaraco', 'giampaolo.rodola', 'christian.heimes', 'tim.golden', 'zach.ware', 'eryksun', 'steve.dower', 'jgosmann', 'mhils', 'abrezovsky']
pr_nums = ['12183']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29515'
versions = ['Python 3.8']

[mhils]

The latest Windows builds for Python 3.5.3/3.6.0 do not export socket.IPPROTO_IPV6, even though e.g. socket.IPV6_V6ONLY is exported. This seems to be wrong to me as IPV6_V6ONLY requires the corresponding socket option level IPPROTO_IPV6 to be actually useful. The same issue at least also applies to IPPROTO_IPV4.

christian.heimes mentioned that this is intended behaviour in https://bugs.python.org/issue6926 as Windows would not define the constants. Now I am all but an expert on this, but it seems to me that IPPROTO_IPV6 is defined in Windows:
https://msdn.microsoft.com/en-us/library/windows/hardware/ff543746(v=vs.85).aspx. Apologies if I'm missing something here.

Python 3.6.0 (v3.6.0:41df79263a11, Dec 23 2016, 07:18:10) [MSC v.1900 32 bit (Intel)] on win32
>>> import socket; socket.IPPROTO_IPV6
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'socket' has no attribute 'IPPROTO_IPV6'

As a workaround, IPPROTO_IPV6 can be substituted with the hardcoded constant 41.

[eryksun]

The macro is defined but not defined. If I insert the following line before the #ifdef check:

    #define IPPROTO_IPV6 IPPROTO_IPV6

then the constant gets added:

    >>> import _socket
    >>> _socket.IPPROTO_IPV6
    41

The same applies to IPPROTO_IPV4 and probably others.

[eryksun]

Unless someone has a better (more automated) way to handle the Winsock IPPROTO enum, I suggest we either special-case the individual tests for MS_WINDOWS when we know that Winsock defines the value; or just define macros for the values in the enum:

    #ifdef MS_WINDOWS /* Macros based on the IPPROTO enum. */
    #define IPPROTO_ICMP IPPROTO_ICMP
    #define IPPROTO_IGMP IPPROTO_IGMP
    #define IPPROTO_GGP IPPROTO_GGP
    #define IPPROTO_TCP IPPROTO_TCP
    #define IPPROTO_PUP IPPROTO_PUP
    #define IPPROTO_UDP IPPROTO_UDP
    #define IPPROTO_IDP IPPROTO_IDP
    #define IPPROTO_ND IPPROTO_ND 
    #define IPPROTO_RAW IPPROTO_RAW
    #define IPPROTO_MAX IPPROTO_MAX
    #if (_WIN32_WINNT >= 0x0501)
    #define IPPROTO_HOPOPTS IPPROTO_HOPOPTS
    #define IPPROTO_IPV4 IPPROTO_IPV4
    #define IPPROTO_IPV6 IPPROTO_IPV6
    #define IPPROTO_ROUTING IPPROTO_ROUTING
    #define IPPROTO_FRAGMENT IPPROTO_FRAGMENT
    #define IPPROTO_ESP IPPROTO_ESP
    #define IPPROTO_AH IPPROTO_AH
    #define IPPROTO_ICMPV6 IPPROTO_ICMPV6
    #define IPPROTO_NONE IPPROTO_NONE
    #define IPPROTO_DSTOPTS IPPROTO_DSTOPTS
    #define IPPROTO_ICLFXBM IPPROTO_ICLFXBM
    #endif /* (_WIN32_WINNT >= 0x0501) */
    #if (_WIN32_WINNT >= 0x0600)
    #define IPPROTO_ST IPPROTO_ST
    #define IPPROTO_CBT IPPROTO_CBT
    #define IPPROTO_EGP IPPROTO_EGP
    #define IPPROTO_IGP IPPROTO_IGP
    #define IPPROTO_RDP IPPROTO_RDP
    #define IPPROTO_PIM IPPROTO_PIM
    #define IPPROTO_PGM IPPROTO_PGM
    #define IPPROTO_L2TP IPPROTO_L2TP
    #define IPPROTO_SCTP IPPROTO_SCTP
    #endif /* (_WIN32_WINNT >= 0x0600) */
    #endif /* MS_WINDOWS */

or call PyModule_AddIntConstant(m, "IPPROTO_ICMP", IPPROTO_ICMP) and so on for each enum value.

[zooba]

We may just want to copy the values from the enum if there are different versions when they were introduced. But if that's not a problem, adding the MS_WINDOWS check is better than defining new macros.

[abrezovsky]

Can confirm this is still a problem in latest versions of 3.5, 3.6, and 3.7

Any progress made on this?

[zooba]

No progress, but I like the extra defines idea best (directly in socketmodule.c, not in a public header file). That's the easiest way to close the gap between (apparently) real constants used on Windows and the preprocessor defines (apparently) used elsewhere.

[giampaolo]

It turns out having this fix would be useful for proceeding with bpo-17561, which right now cannot support dual-stack IPv4/6 on Windows because IPPROTO_IPV6 is missing, see my comment:
#11784 (comment)

[giampaolo]

@eryksun I tried your patch (https://bugs.python.org/issue29515#msg287477) on Windows 10 and it looks good. It introduces the following new constants:

IPPROTO_IGMP
IPPROTO_GGP
IPPROTO_PUP
IPPROTO_IDP
IPPROTO_ND
IPPROTO_MAX
IPPROTO_HOPOPTS
IPPROTO_IPV4
IPPROTO_IPV6
IPPROTO_ROUTING
IPPROTO_FRAGMENT
IPPROTO_ESP
IPPROTO_AH
IPPROTO_ICMPV6
IPPROTO_NONE
IPPROTO_DSTOPTS
IPPROTO_EGP
IPPROTO_PIM
IPPROTO_SCTP

...plus these Windows-only ones for which I had to add an additional PyModule_AddIntMacro() call:

IPPROTO_ICLFXBM
IPPROTO_ST
IPPROTO_CBT
IPPROTO_IGP
IPPROTO_RDP
IPPROTO_PGM
IPPROTO_L2TP

Up 'till now only these ones were exposed:

IPPROTO_ICMP
IPPROTO_TCP
IPPROTO_UDP
IPPROTO_RAW

I think we can proceed with this. Care to provide a patch?

[giampaolo]

@eryk do you mind if I make a PR with your code(I will of course author you)? Regardless from bpo-17561 I think this is an important fix because without IPPROTO_IPV6 is not possible to implement a dual-stack IPv4/6 socket on Windows.

[eryksun]

do you mind if I make a PR with your code(I will of course author you)?

Go for it. I prefer no credit, but you're free to do as you wish.