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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2011-07-03 19:49:16 +0400
committerGerrit Renker <gerrit@erg.abdn.ac.uk>2011-07-04 22:36:33 +0400
commitc0c2015056d7bd69f3554208271407e7e2ee69e5 (patch)
tree8144a35fcb508fe6e9a24442ceb013ad9dda2bad
parent31fcb99d9958bdf04e84224e202f69e6cdac893b (diff)
downloadlinux-c0c2015056d7bd69f3554208271407e7e2ee69e5.tar.xz
dccp: Clean up slow-path input processing
This patch rearranges the order of statements of the slow-path input processing (i.e. any other state than OPEN), to resolve the following issues. 1. Dependencies: the order of statements now better matches RFC 4340, 8.5, i.e. step 7 is before step 9 (previously 9 was before 7), and parsing options in step 8 (which may consume resources) now comes after step 7. 2. Sequence number checks are omitted if in state LISTEN/REQUEST, due to the note underneath the table in RFC 4340, 7.5.3. As a result, CCID processing is now indeed confined to OPEN/PARTOPEN states, i.e. congestion control is performed only on the flow of data packets. This avoids pathological cases of doing congestion control on those messages which set up and terminate the connection. 3. Packets are now passed on to Ack Vector / CCID processing only after - step 7 (receive unexpected packets), - step 9 (receive Reset), - step 13 (receive CloseReq), - step 14 (receive Close) and only if the state is PARTOPEN. This simplifies CCID processing: - in LISTEN/CLOSED the CCIDs are non-existent; - in RESPOND/REQUEST the CCIDs have not yet been negotiated; - in CLOSEREQ and active-CLOSING the node has already closed this socket; - in passive-CLOSING the client is waiting for its Reset. In the last case, RFC 4340, 8.3 leaves it open to ignore further incoming data, which is the approach taken here. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
-rw-r--r--net/dccp/input.c61
1 files changed, 30 insertions, 31 deletions
diff --git a/net/dccp/input.c b/net/dccp/input.c
index 4222e7a654b0..51d5fe5fffba 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -619,20 +619,31 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
return 1;
}
- if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) {
- if (dccp_check_seqno(sk, skb))
- goto discard;
-
- /*
- * Step 8: Process options and mark acknowledgeable
- */
- if (dccp_parse_options(sk, NULL, skb))
- return 1;
+ /* Step 6: Check sequence numbers (omitted in LISTEN/REQUEST state) */
+ if (sk->sk_state != DCCP_REQUESTING && dccp_check_seqno(sk, skb))
+ goto discard;
- dccp_handle_ackvec_processing(sk, skb);
- dccp_deliver_input_to_ccids(sk, skb);
+ /*
+ * Step 7: Check for unexpected packet types
+ * If (S.is_server and P.type == Response)
+ * or (S.is_client and P.type == Request)
+ * or (S.state == RESPOND and P.type == Data),
+ * Send Sync packet acknowledging P.seqno
+ * Drop packet and return
+ */
+ if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
+ dh->dccph_type == DCCP_PKT_RESPONSE) ||
+ (dp->dccps_role == DCCP_ROLE_CLIENT &&
+ dh->dccph_type == DCCP_PKT_REQUEST) ||
+ (sk->sk_state == DCCP_RESPOND && dh->dccph_type == DCCP_PKT_DATA)) {
+ dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
+ goto discard;
}
+ /* Step 8: Process options */
+ if (dccp_parse_options(sk, NULL, skb))
+ return 1;
+
/*
* Step 9: Process Reset
* If P.type == Reset,
@@ -640,31 +651,15 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
* S.state := TIMEWAIT
* Set TIMEWAIT timer
* Drop packet and return
- */
+ */
if (dh->dccph_type == DCCP_PKT_RESET) {
dccp_rcv_reset(sk, skb);
return 0;
- /*
- * Step 7: Check for unexpected packet types
- * If (S.is_server and P.type == Response)
- * or (S.is_client and P.type == Request)
- * or (S.state == RESPOND and P.type == Data),
- * Send Sync packet acknowledging P.seqno
- * Drop packet and return
- */
- } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
- dh->dccph_type == DCCP_PKT_RESPONSE) ||
- (dp->dccps_role == DCCP_ROLE_CLIENT &&
- dh->dccph_type == DCCP_PKT_REQUEST) ||
- (sk->sk_state == DCCP_RESPOND &&
- dh->dccph_type == DCCP_PKT_DATA)) {
- dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
- goto discard;
- } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
+ } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { /* Step 13 */
if (dccp_rcv_closereq(sk, skb))
return 0;
goto discard;
- } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
+ } else if (dh->dccph_type == DCCP_PKT_CLOSE) { /* Step 14 */
if (dccp_rcv_close(sk, skb))
return 0;
goto discard;
@@ -679,8 +674,12 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
__kfree_skb(skb);
return 0;
- case DCCP_RESPOND:
case DCCP_PARTOPEN:
+ /* Step 8: if using Ack Vectors, mark packet acknowledgeable */
+ dccp_handle_ackvec_processing(sk, skb);
+ dccp_deliver_input_to_ccids(sk, skb);
+ /* fall through */
+ case DCCP_RESPOND:
queued = dccp_rcv_respond_partopen_state_process(sk, skb,
dh, len);
break;