tornadoweb / tornadoweb/tornado

Use stricter/platform-independent IP parsing for X-Forwarded-For

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httpserver
Dominant language
Python
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Description

netutil.is_valid_ip uses getaddrinfo in AI_NUMERICHOST mode to parse IP addresses. This method accepts some surprising formats (e.g. "x.y" is parsed as x.(y >> 16).((y>>8)&0xff).(y&0xff), at least on mac and linux). It would be good to limit this to a more formal specification (e.g. the one in http://tools.ietf.org/html/rfc3986#section-3.2.2, which is cited in http://tools.ietf.org/html/draft-ietf-appsawg-http-forwarded-10#section-6.1).

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at netutil.is_valid_ip and compare its getaddrinfo behavior in AI_NUMERICHOST mode with RFC 3986 section 3.2.2 and the Forwarded-header guidance cited in the issue. Done means X-Forwarded-For validation rejects surprising formats such as "x.y" and behaves consistently across macOS and Linux.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
networking
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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