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

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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>
This commit is contained in:
Gerrit Renker 2008-09-04 07:30:19 +02:00
parent 09856c1089
commit 51c7d4fa26
6 changed files with 24 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/networking/dccp.txt
View File

@ -141,7 +141,8 @@ rx_ccid = 2
Default CCID for the receiver-sender half-connection; see tx_ccid.
seq_window = 100
The initial sequence window (sec. 7.5.2).
The initial sequence window (sec. 7.5.2) of the sender. This influences
the local ackno validity and the remote seqno validity windows (7.5.1).
tx_qlen = 5
The size of the transmit buffer in packets. A value of 0 corresponds

24
include/linux/dccp.h
View File

@ -363,19 +363,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
/* FIXME: for now we're default to 1 but it should really be 0 */
#define DCCPF_INITIAL_SEND_NDP_COUNT 1
/**
* struct dccp_minisock - Minimal DCCP connection representation
*
* Will be used to pass the state from dccp_request_sock to dccp_sock.
*
* @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
*/
struct dccp_minisock {
__u64 dccpms_sequence_window;
};
extern void dccp_minisock_init(struct dccp_minisock *dmsk);
/**
* struct dccp_request_sock - represent DCCP-specific connection request
* @dreq_inet_rsk: structure inherited from
@ -464,13 +451,14 @@ struct dccp_ackvec;
* @dccps_timestamp_time - time of receiving latest @dccps_timestamp_echo
* @dccps_l_ack_ratio - feature-local Ack Ratio
* @dccps_r_ack_ratio - feature-remote Ack Ratio
* @dccps_l_seq_win - local Sequence Window (influences ack number validity)
* @dccps_r_seq_win - remote Sequence Window (influences seq number validity)
* @dccps_pcslen - sender partial checksum coverage (via sockopt)
* @dccps_pcrlen - receiver partial checksum coverage (via sockopt)
* @dccps_send_ndp_count - local Send NDP Count feature (7.7.2)
* @dccps_ndp_count - number of Non Data Packets since last data packet
* @dccps_mss_cache - current value of MSS (path MTU minus header sizes)
* @dccps_rate_last - timestamp for rate-limiting DCCP-Sync (RFC 4340, 7.5.4)
* @dccps_minisock - associated minisock (accessed via dccp_msk)
* @dccps_featneg - tracks feature-negotiation state (mostly during handshake)
* @dccps_hc_rx_ackvec - rx half connection ack vector
* @dccps_hc_rx_ccid - CCID used for the receiver (or receiving half-connection)
@ -504,12 +492,13 @@ struct dccp_sock {
__u32 dccps_timestamp_time;
__u16 dccps_l_ack_ratio;
__u16 dccps_r_ack_ratio;
__u64 dccps_l_seq_win:48;
__u64 dccps_r_seq_win:48;
__u8 dccps_pcslen:4;
__u8 dccps_pcrlen:4;
__u8 dccps_send_ndp_count:1;
__u64 dccps_ndp_count:48;
unsigned long dccps_rate_last;
struct dccp_minisock dccps_minisock;
struct list_head dccps_featneg;
struct dccp_ackvec *dccps_hc_rx_ackvec;
struct ccid *dccps_hc_rx_ccid;
@ -527,11 +516,6 @@ static inline struct dccp_sock *dccp_sk(const struct sock *sk)
return (struct dccp_sock *)sk;
}
static inline struct dccp_minisock *dccp_msk(const struct sock *sk)
{
return (struct dccp_minisock *)&dccp_sk(sk)->dccps_minisock;
}
static inline const char *dccp_role(const struct sock *sk)
{
switch (dccp_sk(sk)->dccps_role) {

16
net/dccp/dccp.h
View File

@ -409,23 +409,21 @@ static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
static inline void dccp_update_gsr(struct sock *sk, u64 seq)
{
struct dccp_sock *dp = dccp_sk(sk);
const struct dccp_minisock *dmsk = dccp_msk(sk);
dp->dccps_gsr = seq;
dccp_set_seqno(&dp->dccps_swl,
dp->dccps_gsr + 1 - (dmsk->dccpms_sequence_window / 4));
dccp_set_seqno(&dp->dccps_swh,
dp->dccps_gsr + (3 * dmsk->dccpms_sequence_window) / 4);
/* Sequence validity window depends on remote Sequence Window (7.5.1) */
dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);
}
static inline void dccp_update_gss(struct sock *sk, u64 seq)
{
struct dccp_sock *dp = dccp_sk(sk);
dp->dccps_awh = dp->dccps_gss = seq;
dccp_set_seqno(&dp->dccps_awl,
(dp->dccps_gss -
dccp_msk(sk)->dccpms_sequence_window + 1));
dp->dccps_gss = seq;
/* Ack validity window depends on local Sequence Window value (7.5.1) */
dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);
dp->dccps_awh = dp->dccps_gss;
}
static inline int dccp_ack_pending(const struct sock *sk)

13
net/dccp/feat.c
View File

@ -52,8 +52,17 @@ static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
{
if (!rx)
dccp_msk(sk)->dccpms_sequence_window = seq_win;
struct dccp_sock *dp = dccp_sk(sk);
if (rx) {
dp->dccps_r_seq_win = seq_win;
/* propagate changes to update SWL/SWH */
dccp_update_gsr(sk, dp->dccps_gsr);
} else {
dp->dccps_l_seq_win = seq_win;
/* propagate changes to update AWL */
dccp_update_gss(sk, dp->dccps_gss);
}
return 0;
}

11
net/dccp/minisocks.c
View File

@ -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 */

2
net/dccp/proto.c
View File

@ -180,8 +180,6 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
struct dccp_sock *dp = dccp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
dccp_minisock_init(&dp->dccps_minisock);
icsk->icsk_rto = DCCP_TIMEOUT_INIT;
icsk->icsk_syn_retries = sysctl_dccp_request_retries;
sk->sk_state = DCCP_CLOSED;