Implement socket.if_{nametoindex,indextoname} for Windows

[dtantsur]

BPO	37007
Nosy	@pfmoore, @tjguk, @dtantsur, @zware, @zooba, @ZackerySpytz
PRs	bpo-37007: Implement socket.if_nametoindex() and socket.if_indextoname() on Windows #13522

^{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 2019-05-29.21:58:45.671>
created_at = <Date 2019-05-22.11:01:24.930>
labels = ['type-feature', '3.8', 'OS-windows']
title = 'Implement socket.if_{nametoindex,indextoname} for Windows'
updated_at = <Date 2019-05-29.21:58:45.671>
user = 'https://github.com/dtantsur'

bugs.python.org fields:

activity = <Date 2019-05-29.21:58:45.671>
actor = 'steve.dower'
assignee = 'none'
closed = True
closed_date = <Date 2019-05-29.21:58:45.671>
closer = 'steve.dower'
components = ['Windows']
creation = <Date 2019-05-22.11:01:24.930>
creator = 'dtantsur'
dependencies = []
files = []
hgrepos = []
issue_num = 37007
keywords = ['patch']
message_count = 8.0
messages = ['343171', '343285', '343303', '343347', '343892', '343900', '343913', '343925']
nosy_count = 6.0
nosy_names = ['paul.moore', 'tim.golden', 'dtantsur', 'zach.ware', 'steve.dower', 'ZackerySpytz']
pr_nums = ['13522']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue37007'
versions = ['Python 3.8']

[dtantsur]

These two calls are currently Unix-only in the socket module. However, Windows supports them starting with Vista:
https://docs.microsoft.com/en-us/windows/desktop/api/netioapi/nf-netioapi-if_indextoname
https://docs.microsoft.com/en-us/windows/desktop/api/netioapi/nf-netioapi-if_nametoindex

I checked with ctypes and they do seem to work. Unfortunately, if_nameindex is not implemented.

[ZackerySpytz]

I've created a PR for this issue. Few changes are needed to implement these functions on Windows.

[zooba]

Is it worth also implementing if_nameindex() using (I assume) GetIfTable2Ex 1? Or maybe just the simpler GetIfTable is sufficient - I'm not sure exactly what semantics Unix if_nameindex() has, whether it includes all logical adapters.

[dtantsur]

That would be fantastic, but I did not dare asking for it :)

This is how the output of if_nameindex looks on my Fedora 29:

[(1, 'lo'), (2, 'enp0s31f6'), (3, 'wlp4s0'), (4, 'virbr0'), (5, 'virbr0-nic'), (12, 'tun0')]

It includes the loopback, two real adapters (ethernet and wifi) and devices apparently created by libvirt.

This is how it looks on my OpenStack testing environment:

[(1, 'lo'), (2, 'eth0'), (3, 'virbr0'), (4, 'virbr0-nic'), (5, 'ovs-system'), (6, 'br-int'), (7, 'br-ex'), (8, 'brbm'), (9, 'br-tun'), (14, 'ovs-node-0i1'), (15, 'tap-node-0i1'), (16, 'ovs-node-0i2'), (17, 'tap-node-0i2'), (18, 'ovs-node-1i1'), (19, 'tap-node-1i1'), (20, 'ovs-node-1i2'), (21, 'tap-node-1i2'), (22, 'ovs-node-2i1'), (23, 'tap-node-2i1'), (24, 'ovs-node-2i2'), (25, 'tap-node-2i2'), (26, 'ovs-tap'), (27, 'brbm-tap'), (34, 'br-inspector'), (35, 'brbm-inspector'), (55, 'macvtap2'), (56, 'macvtap3'), (79, 'macvtap0'), (80, 'macvtap1')]

It seems to actually include everything.

[ZackerySpytz]

Well, it turns out that implementing if_nameindex() on Windows using GetIfTable2Ex() was also quite simple. I've updated the PR.

[zooba]

Great, thanks Zackery! (And thanks for the ping - I don't notice GitHub notifications.)

Had a few comments about error handling, but it looks great.

[ZackerySpytz]

Thanks, Steve. I've addressed your comments on the PR.

[zooba]

New changeset 8f96c9f by Steve Dower (Zackery Spytz) in branch 'master':
bpo-37007: Implement socket.if_nametoindex(), if_indextoname() and if_nameindex() on Windows (GH-13522)
8f96c9f