Commit f26e739d authored by Mike Perry's avatar Mike Perry
Browse files

Padding spec update for Bug 30992's machine_ctr field.

parent 87eefe8c

padding-spec.txt

+12 −1
Original line number Diff line number Diff line
@@ -325,13 +325,19 @@ the anonymity and load-balancing implications of their choices. 
       u8 command IN [CIRCPAD_COMMAND_START, CIRCPAD_COMMAND_STOP];



       u8 machine_type IN [CIRCPAD_MACHINE_CIRC_SETUP];



       u8 unused; // Formerly echo_request



       u32 machine_ctr;

     };



  When a client wants to start a circuit padding machine, it first checks that

  the desired destination hop advertises the appropriate subprotocol version for

  that machine. It then sends a circpad_negotiate cell to that hop with

  command=CIRCPAD_COMMAND_START, and machine_type=CIRCPAD_MACHINE_CIRC_SETUP (for

  the circ setup machine, the destination hop is the second hop in the circuit).

  the circ setup machine, the destination hop is the second hop in the

  circuit). The machine_ctr is the count of which machine instance this is on

  the circuit. It is used to disambiguate shutdown requests.



  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
@@ -343,6 +349,8 @@ the anonymity and load-balancing implications of their choices. 
       u8 response IN [CIRCPAD_RESPONSE_OK, CIRCPAD_RESPONSE_ERR];



       u8 machine_type IN [CIRCPAD_MACHINE_CIRC_SETUP];



       u32 machine_ctr;

     };



  If the machine is supported, the response field will contain
@@ -352,6 +360,9 @@ the anonymity and load-balancing implications of their choices. 
  (clients MUST only send circpad_negotiate, and relays MUST only send

  circpad_negotiated for this purpose).



  If the machine_ctr does not match the current machine instance count

  on the circuit, the command is ignored.



3.2. Circuit Padding Machine Message Management



  Clients MAY send padding cells towards the relay before receiving the