Document relay commands for circpad cells.

2 files changed, 10 insertions, 3 deletions

diff --git a/padding-spec.txt b/padding-spec.txt
index b9d99b7..f6356ed 100644
--- a/padding-spec.txt
+++ b/padding-spec.txt
@@ -309,8 +309,12 @@ the anonymity and load-balancing implications of their choices.
 
   Because circuit padding machines only become active at certain points in
   circuit lifetime, and because more than one padding machine may be active at
-  any given point in circuit lifetime, there is also a padding negotiation cell,
-  with fields as follows:
+  any given point in circuit lifetime, there is also a padding negotiation
+  cell and a negotiated response. These are relay commands 41 and 42, with
+  relay headers as per section 6.1 of tor-spec.txt.
+
+  The fields of the relay cell Data payload of a negotiate request are
+  as follows:
 
      const CIRCPAD_COMMAND_STOP = 1;
      const CIRCPAD_COMMAND_START = 2;
@@ -341,7 +345,8 @@ the anonymity and load-balancing implications of their choices.
 
   When a relay receives a circpad_negotiate cell, it checks that it supports
   the requested machine, and sends a circpad_negotiated cell, which is formatted
-  as follows:
+  in the data payload of a relay cell with command number 42 (see tor-spec.txt
+  section 6.1), as follows:
 
      struct circpad_negotiated {
        u8 version IN [0];
diff --git a/tor-spec.txt b/tor-spec.txt
index 40ea4cc..af16fa4 100644
--- a/tor-spec.txt
+++ b/tor-spec.txt
@@ -1596,6 +1596,8 @@ see tor-design.pdf.
 
         32..40 -- Used for hidden services; see rend-spec-{v2,v3}.txt.
 
+        41..42 -- Used for circuit padding; see Section 3 of padding-spec.txt.
+
    Commands labelled as "forward" must only be sent by the originator
    of the circuit. Commands labelled as "backward" must only be sent by
    other nodes in the circuit back to the originator. Commands marked