Magnet._INFOHASH_REGEX accepts trailing garbage (missing alternation group)

[chirag127]

Problem

Magnet._INFOHASH_REGEX at torf/_magnet.py:52 has an unwrapped alternation, so the $ only anchors the second branch. The first branch (^[0-9a-f]{40}) matches even when trailing garbage follows, and Magnet.infohash setter (:125) and xt setter (:104) both accept the invalid value.

Steps

from torf import Magnet
bad = 'a' * 40 + 'GARBAGE_HERE!!!'
m = Magnet(xt=bad)
print(repr(m.infohash), len(m.infohash))

Expected

MagnetError: Invalid exact topic ("xt") (same as _XT_REGEX, which correctly wraps its alternation).

Actual

'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaGARBAGE_HERE!!!' 55

Fix

r'^([0-9a-f]{40}|[a-z2-7]{32})$' (mirror _XT_REGEX at :53).

Environment

• torf 4.3.1 (master @ 2026-05-01)
• Python 3.9-3.14 per pyproject.toml

Thanks for maintaining rndusr/torf!

[rndusr]

Thank you for the great report! I pushed a fix. Can you confirm? It seems to me that this is technically a bug but I can't think of a scenario in which it would actually cause any trouble. Did you noticed this by chance or is this an actual issue for you that warrants a bugfix release?