Opened 3 years ago

Last modified 2 years ago

#22203 new enhancement

Should a hup reload the geoip files?

Reported by: arma Owned by:
Priority: Medium Milestone: Tor: unspecified
Component: Core Tor/Tor Version:
Severity: Normal Keywords: intro tor-client tor-relay geoip hup configuration reload metrics-geoip
Cc: karsten Actual Points:
Parent ID: Points: 2
Reviewer: Sponsor:

Description (last modified by arma)

In config.c in config_maybe_load_geoip_files_() we have this line:

  /* XXXX Reload GeoIPFile on SIGHUP. -NM */

and sure enough, it looks like there's nothing in main.c's do_hup() that would make us reload the geoip files.

It would be relatively easy to do I think:

  • In do_hup(), right around the call to routerlist_reset_warnings(), we call something in geoip.c that tells it to no longer consider itself initialized. Maybe that call is something like clear_geoip_db().
  • Then in config_maybe_load_geoip_files_(), since geoip_is_loaded() returns 0, it loads them.

Things get tricky though: catalyst asked if reloading the geoip files messes up the statistics gathering.

If reloading the geoip files *does* mess up statistics gathering, we have ourselves a minor bug, since config_maybe_load_geoip_files_() does reload them if the GeoIPFile location changes.

But it turns out to be more complicated than that, since geoip_load_file() only clears selective things: it clears geoip_ipv4_entries and geoip_ipv6_entries, but it leaves geoip_countries alone! And I see elsewhere, at the bottom of geoip_note_client_seen(), that we are keeping statistics directly in the geoip_countries smartlist:

      geoip_country_t *country = smartlist_get(geoip_countries, country_idx);

So we would not want to call clear_geoip_db() on hup, or we'd lose some stats.

I guess that means if we want to make do_hup reload the geoip stats file, the better (non-invasive) plan is to have a boolean want_to_reload_geoip{4,6} in geoip.c that we turn on in do_hup, and then we check the right boolean in geoip_is_loaded().

I think there's a big argument for growing some good unit tests here, around "what happens when we reload this, collect those stats, reload that, examine those other stats, etc", since things are either subtly broken right now, or awfully fragile.

Child Tickets

Change History (5)

comment:1 Changed 3 years ago by arma

Description: modified (diff)

comment:2 Changed 3 years ago by karsten

Cc: karsten added

I'm not arguing against fixing bugs or writing better tests.

But what's the practical value of being able to reload the geoip files? We only ship new geoip files in new releases, and people will need to restart their tor process in order to upgrade to those anyway. I'd guess that only a tiny fraction of operators would want to put in newer geoip files manually and reload their tor process. And those statistics are hardly statistically relevant.

So, I was curious how old the geoip files used by relays and bridges are, which is very likely related to how old the tor versions running in the network are. Relays and bridges contain geoip-db-digest lines with SHA-1 digests of their geoip file, and we can extract those digests from tor's Git repo. Here are some statistics on the age of geoip files mentioned in descriptors published between January 1, 2017 and May 4, 2017:

# Relays
        Min.      1st Qu.       Median         Mean      3rd Qu.         Max. 
"2009-06-03" "2015-03-03" "2015-12-01" "2016-02-15" "2017-01-04" "2017-04-04" 

# Bridges
        Min.      1st Qu.       Median         Mean      3rd Qu.         Max. 
"2009-06-03" "2016-11-03" "2016-12-07" "2016-11-04" "2017-02-08" "2017-04-04" 

These statistics say that the geoip files used by relays are more than 1 year old on average and those used by bridges a couple of months. (No idea why the difference between the two is so big.)

But anyway, it seems like improving support for manually reloading geoip files won't make much of a difference.

What we should consider instead is support for downloading signed geoip files from the directory authorities. That will be much more effective. But it's also a lot of work and requires looking into licenses.

comment:3 Changed 3 years ago by dgoulet

Milestone: Tor: unspecified

comment:4 Changed 3 years ago by nickm

Keywords: intro tor-client tor-relay geoip hup configuration reload added
Points: 2

comment:5 Changed 2 years ago by irl

Keywords: metrics-geoip added
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