[New-bugs-announce] [issue27612] socket.gethostbyname resolving octal IP addresses incorrectly

[Matt Robenolt]

New submission from Matt Robenolt:

This also affects socket.getaddrinfo on macOS only, but is fine on Linux. I've not tested on Windows to see behavior there.

Given the IP address `0177.0000.0000.0001`, which is a valid octal format representing `127.0.0.1`, we can see varying results. Confirmed in both python 2.7 and 3.5.

First, socket.gethostbyname is always wrong, and always returns `177.0.0.1`:

```
>>> socket.gethostbyname('0177.0000.0000.0001')
'177.0.0.1'
```

This can be seen on both Linux and macOS.

With `socket.getaddrinfo`, resolution is correct on Linux, but the bad 177.0.0.1 on macOS.

Linux:
```
>>> socket.getaddrinfo('0177.0000.0000.0001', None)[0]
(2, 1, 6, '', ('127.0.0.1', 0))
```

macOS:
```
>>> socket.getaddrinfo('0177.0000.0000.0001', None)[0]
(2, 2, 17, '', ('177.0.0.1', 0))
```

This behavior exists in both 2.7.12 and 3.5.2 at least. I haven't tested many others, but I assume pretty universal.

----------
components: Library (Lib)
messages: 271237
nosy: mattrobenolt
priority: normal
severity: normal
status: open
title: socket.gethostbyname resolving octal IP addresses incorrectly
type: behavior
versions: Python 2.7, Python 3.5

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue27612>
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