On 25 Dec 2017, at 07:13, Damian Johnson atagar@torproject.org wrote:
Done!
- the file now starts with a type and a version line:
/* type=fallback */ /* version=2.0.0 */
- extrainfo is mandatory (occasionally we won't get a descriptor, so
we'll warn and mark the relay extrainfo=0)
- each fallback entry ends with /* ===== */
Sweet, thanks Tim!
- is 6 extra info caches (up from 4) enough in a list of 150?
Hmmm. Can't say on Stem's side I have an opinion on this. It doesn't rely on fallback directories for anything so extrainfo caches aren't a concern.
So stem just uses a mix of fallbacks and authorities? Good, that's what Tor does. I think we will be fine then.
- do you want the delimiter before the first fallback entry as well?
Stem doesn't care about a delimiter before the first entry but that seems like a good idea so we have a clear separation between comments and the start of the machine readable section.
I made the header end with a delimiter, and I made the list of entries start with a delimiter:
https://trac.torproject.org/projects/tor/attachment/ticket/22759/fallback_di...
This means that parsers can (and should) ingore the human-readable second section.
A detail Stem does care about is that the last entry ends with a delimiter. If it doesn't that's fine, but code is a tad simpler if we ensure it does. :)
It does and it will continue to.
On 25 Dec 2017, at 07:26, Iain Learmonth irl@torproject.org wrote:
As we are planning to also add a parser to metrics-lib (#24434), would it be possible to get a full description of the format of the file possibly in RFC5234 format so that we can check that the generator and parsers all match up to that specification?
I have written up a format in the standard torspec style:
https://github.com/teor2345/torspec/blob/fallback-format-2/fallback-spec.txt
It is deliberately under-specified, please let me know if this causes any trouble when writing the parser, and I will tighten it up.
It's not ABNF/RFC5234, it's rather restrictive, and strict ABNF is unreadable for case sensitive strings. I am happy to put an ABNF spec in an appendix, if someone wants to write one.
T
-- Tim Wilson-Brown (teor)
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