From e24e9cb0c4f9bfbb7907549b064a7efc50568581 Mon Sep 17 00:00:00 2001 From: Nick Mathewson Date: Thu, 13 May 2021 13:11:56 -0400 Subject: Document current circid selection behavior --- tor-spec.txt | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/tor-spec.txt b/tor-spec.txt index 62b7d5d..d044542 100644 --- a/tor-spec.txt +++ b/tor-spec.txt @@ -1000,6 +1000,12 @@ see tor-design.pdf. belong to any circuit: CircID 0 must not be used for circuits. No other CircID value, including 0x8000 or 0x80000000, is reserved. + Existing Tor implementations choose their CircID values at random from + among the available unused values. To avoid distinguishability, new + implementations should do the same. Implementations MAY give up and stop + attempting to build new circuits on a channel, if a certain number of + randomly chosen CircID values are all in use (today's Tor stops after 64). + 5.1.2. EXTEND and EXTENDED cells To extend an existing circuit, the client sends an EXTEND or EXTEND2 -- cgit v1.2.3-54-g00ecf