On 7/13/07, Gerrit Renker <gerrit@xxxxxxxxxxxxxx> wrote: > [DCCP]: Dedicated auxiliary states to support passive-close > > This adds two auxiliary states to deal with passive closes: > * PASSIVE_1 (reached from OPEN via reception of Close) and > * PASSIVE_2 (reached from OPEN via reception of CloseReq) > to the internal state machine. > > The PASSIVE_1 and PASSIVE_2 states represent the two ways a passive-close > can happen in DCCP. The addition of these states is not merely to > increase clarity. These states are required by the implementation to > allow a receiver to process unread data before acknowledging the received > connection-termination-request (i.e. the Close/CloseReq). > > Fix: > ---- > This patch uses the PASSIVE_1 and PASSIVE_2 states to explicitly refer to > passive-closing states and to protect against external wipeout of internal > receive queues. The macroscopic behaviour is compatible with RFC 4340, but > without the auxiliary states, buggy, absurd and abnormal behaviour of the > socket API will continue. Which is to say, without auxiliary states it does > not work. > > As a consequence, the count of DCCP_STATE_MASK has been increased, to account > for the number of new states. > > > Implementation Note: > -------------------- > To keep compatibility with sk_stream_wait_connect(): > * DCCP_CLOSING continues to map into TCP_CLOSING (since this state can be > either passive- or active-close) > * DCCP_CLOSEREQ maps into TCP_FIN_WAIT1 (since it is always active-close) > > It is tempting to keep the clever merge of the CLOSEREQ and CLOSING states. > However, with the number of possible state transitions, this would require: > > * quite a number of `if' statements to distinguish all predecessors of > the CLOSING state (server/client, active/passive, server timewait yes/no); > > * two different branches from the CLOSING state: > - to TIMEWAIT if it is not an active server-close without keeping timewait state > - to CLOSED otherwise (and requiring to receive a Close instead of a Reset). > > In light of this, I think it is cleaner to implement separate CLOSEREQ and CLOSING > states (this is done by the subsequent patches). > > Further documentation is on http://www.erg.abdn.ac.uk/users/gerrit/dccp/docs/closing_states/ > > > Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx> This was signed off by me on Sep 6th but seems to have got lost so: Signed-off-by: Ian McDonald <ian.mcdonald@xxxxxxxxxxx> - To unsubscribe from this list: send the line "unsubscribe dccp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
