commit e24e9cb0c4f9bfbb7907549b064a7efc50568581 Author: Nick Mathewson nickm@torproject.org Date: Thu May 13 13:11:56 2021 -0400
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