From e9c950af8263f57a832ff0434900d32e1dffe35d Mon Sep 17 00:00:00 2001 From: Nick Mathewson Date: Fri, 2 Apr 2021 12:37:13 -0400 Subject: src/config/README: add documentation for geoip format. --- src/config/README | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/src/config/README b/src/config/README index cb2debb88f..4553325e57 100644 --- a/src/config/README +++ b/src/config/README @@ -33,3 +33,32 @@ torrc.sample.in: most people shouldn't mess with. +============================== + +On the geoip format: + +Our geoip files are line-oriented. Any empty line, or line starting +with a #, is ignored. + +All other lines are composed of three comma-separated values: +START,END,CC. For the geoip file, START and END are IPv4 addresses +as expressed as 32-bit integers (such as 3325256709 to represent +198.51.100.5). For the geoip6 file, START and END are IPv6 +addresses, with no brackets. In both cases CC is a two-character +country code. + +The semantic meaning of a line START,END,CC is that all addresses +between START and END _inclusive_ should be mapped to the country code +CC. + +We guarantee that all entries within these files are disjoint -- +that is, there is no address that is matched by more than one +line. We also guarantee that all entries within these files are +sorted in numerically ascending order by address. + +Thus, one effective search algorithm here is to perform a binary +search on all the entries in the file. + +Note that there _are_ "gaps" in these databases: not every possible +address maps to a country code. In those cases, Tor reports the +country as ??. -- cgit v1.2.3-54-g00ecf