[DCCP]: Update comments on precisely which packets can be retransmitted
authorGerrit Renker <gerrit@erg.abdn.ac.uk>
Mon, 13 Nov 2006 15:07:51 +0000 (13:07 -0200)
committerDavid S. Miller <davem@sunset.davemloft.net>
Sun, 3 Dec 2006 05:22:16 +0000 (21:22 -0800)
commit08a29e41bb6d6516b0f65e19381f537168d1768e
tree618fab853176e620311c495959e038018fb14d8e
parent75356f27ed4f85bd789a822bca3fc5e92e334140
[DCCP]: Update comments on precisely which packets can be retransmitted

This updates program documentation: spell out precise conditions about
which packets are eligible for retransmission (which is actually quite
hard to extract from RFC 4340).

It is based on the following table derived from RFC 4340:

+-----------+---------------------------------+---------------------+
|   Type    | Retransmit?                     |  Remark             |
+-----------+---------------------------------+---------------------+
| Request   |  in client-REQUEST state        | sec. 8.1.1          |
| Response  |  NEVER                          | SHOULD NOT, 8.1.3   |
| Data      |  NEVER                          | unreliable protocol |
| Ack       |  possible in client-PARTOPEN    | sec. 8.1.5          |
| DataAck   |  NEVER                          | unreliable protocol |
| CloseReq  |  only in server-CLOSEREQ state  | MUST, sec. 8.3      |
| Close     |  in node-CLOSING state          | MUST, sec. 8.3      |
+-----------+-------------------------------------------------------+
| Reset     |  only in response to other packets                    |
| Sync      |  only in response to sequence-invalid packets (7.5.4) |
| SyncAck   |  only in response to Sync packets                     |
+-----------+-------------------------------------------------------+

Hence the only packets eligible for retransmission are:
       * Requests in client-REQUEST  state (sec. 8.1.1)
       * Acks     in client-PARTOPEN state (sec. 8.1.5)
       * CloseReq in server-CLOSEREQ state (sec. 8.3)
       * Close    in   node-CLOSING  state (sec. 8.3)

I had meant to put in a check for these types too, but have left that
for later.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
net/dccp/timer.c