Reject directory circuits early if they are too skewed.

If we get a connection to a directory that tells us that it's a month in the future, any consensus that it believes in will almost certainly be too new for us to actually use.

(Similarly, if the directory says it's a month in the past, any consensus it believes in will almost certainly be too old for us to use. But we already avoid getting such consensus documents by setting a reasonable If-Modified-Since time.)

We could actually tolerate even more skew than we do with this branch, but IMO it's not a great idea to do so.

This branch is based on top of !500 (merged); only the final 3 commits are new. It's probably best to review !500 (merged) first.

Closes #466 (closed)

requested review from @eta

assigned to @nickm

approved this merge request

added 62 commits

• 2e99c9fe...9d8ce432 - 61 commits from branch tpo/core:main
• fb432924 - Merge branch 'main' into 'ticket_466'

Compare with previous version

enabled an automatic merge when the pipeline for fb432924 succeeds

merged

mentioned in commit 18d7ece7