dccp: Implement both feature-local and feature-remote Sequence Window feature

This adds full support for local/remote Sequence Window feature, from which the 
  * sequence-number-validity (W) and 
  * acknowledgment-number-validity (W') windows 
derive as specified in RFC 4340, 7.5.3. 

Specifically, the following changes are introduced:
  * integrated new socket fields into dccp_sk;
  * updated the update_gsr/gss routines with regard to these fields;
  * updated handler code: the Sequence Window feature is located at the TX side,
    so the local feature is meant if the handler-rx flag is false;
  * the initialisation of `rcv_wnd' in reqsk is removed, since
    - rcv_wnd is not used by the code anywhere;
    - sequence number checks are not done in the LISTEN state (cf. 7.5.3);
    - dccp_check_req checks the Ack number validity more rigorously;
  * the `struct dccp_minisock' became empty and is now removed.

Until the handshake completes with activating negotiated values, the local/remote
Sequence-Window values are undefined and thus can not reliably be estimated.
This issue is addressed in a separate patch.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>

1 files changed, 0 insertions, 11 deletions

diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index 0ebf8ebcf3de..0ecb19c5e8ce 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -42,11 +42,6 @@ struct inet_timewait_death_row dccp_death_row = {
 
 EXPORT_SYMBOL_GPL(dccp_death_row);
 
-void dccp_minisock_init(struct dccp_minisock *dmsk)
-{
-        dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
-}
-
 void dccp_time_wait(struct sock *sk, int state, int timeo)
 {
         struct inet_timewait_sock *tw = NULL;
@@ -110,7 +105,6 @@ struct sock *dccp_create_openreq_child(struct sock *sk,
                 struct dccp_request_sock *dreq = dccp_rsk(req);
                 struct inet_connection_sock *newicsk = inet_csk(newsk);
                 struct dccp_sock *newdp = dccp_sk(newsk);
-                struct dccp_minisock *newdmsk = dccp_msk(newsk);
 
                 newdp->dccps_role           = DCCP_ROLE_SERVER;
                 newdp->dccps_hc_rx_ackvec   = NULL;
@@ -128,10 +122,6 @@ struct sock *dccp_create_openreq_child(struct sock *sk,
                  *    Initialize S.GAR := S.ISS
                  *    Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
                  */
-
-                /* See dccp_v4_conn_request */
-                newdmsk->dccpms_sequence_window = req->rcv_wnd;
-
                 newdp->dccps_gar = newdp->dccps_iss = dreq->dreq_iss;
                 dccp_update_gss(newsk, dreq->dreq_iss);
 
@@ -289,7 +279,6 @@ int dccp_reqsk_init(struct request_sock *req,
 
         inet_rsk(req)->rmt_port   = dccp_hdr(skb)->dccph_sport;
         inet_rsk(req)->acked      = 0;
-        req->rcv_wnd              = sysctl_dccp_feat_sequence_window;
         dreq->dreq_timestamp_echo = 0;
 
         /* inherit feature negotiation options from listening socket */