From b729833befc66d94ce0510356290586e43402dee Mon Sep 17 00:00:00 2001 From: Nick Mathewson Date: Wed, 1 Feb 2017 08:54:07 -0500 Subject: Explain more about primary guards and about building circuits In path-spec: explain our rules (post-21242) for waiting to build circuits. In guard-spec: - explain what to do about missing descriptors - explain parallel use of multiple primary guards, based on parameters. --- guard-spec.txt | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'guard-spec.txt') diff --git a/guard-spec.txt b/guard-spec.txt index 59c66b8..87e16a7 100644 --- a/guard-spec.txt +++ b/guard-spec.txt @@ -451,8 +451,10 @@ When we want to build a circuit, and we need to pick a guard: * If any entry in PRIMARY_GUARDS has {is_reachable} status of - or , return the first such guard. The circuit is - . + or , return one of the first + {NUM_USABLE_PRIMARY_GUARDS} or + {NUM_USABLE_PRIMARY_DIRECTORY_GUARDS} such guards, chosen + uniformly at random. The circuit is . [Note: We do not use {is_pending} on primary guards, since we are willing to try to build multiple circuits through them @@ -620,6 +622,18 @@ circuits are neither built nor in-progress; that circuits are built; and that the other states are in-progress. +4.12. When we are missing descriptors + [Section:MISSING_DESCRIPTORS] + + We need either a router descriptor or a microdescriptor in order + to build a circuit through a guard. If we do not have such a + descriptor for a guard, we can still use the guard for one-hop + directory fetches, but not for longer circuits. + + (Also, when we are missing descriptors for our first + {NUM_USABLE_PRIMARY_GUARDS} primary guards, we don't build + circuits at all until we have fetched them.) + A. Appendices A.1. Parameters with suggested values. [Section:PARAM_VALS] @@ -663,6 +677,10 @@ A.1. Parameters with suggested values. [Section:PARAM_VALS] {param:GUARD_CONFIRMED_MIN_LIFETIME} -- 60 days + {param:NUM_USABLE_PRIMARY_GUARDS} -- 1 + + {param:NUM_USABLE_PRIMARY_DIRECTORY_GUARDS} -- 3 + A.2. Random values [Section:RANDOM] Frequently, we want to randomize the expiration time of something -- cgit v1.2.3-54-g00ecf