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Commit 51c7d4fa authored by Gerrit Renker's avatar Gerrit Renker
Browse files

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: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
parent 09856c10

Documentation/networking/dccp.txt

+2 −1
Original line number Diff line number Diff line
@@ -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

include/linux/dccp.h

+4 −20
Original line number Diff line number Diff line
@@ -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) {

net/dccp/dccp.h

+7 −9
Original line number Diff line number Diff line
@@ -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)

net/dccp/feat.c

+11 −2
Original line number Diff line number Diff line
@@ -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;

}

net/dccp/minisocks.c

+0 −11
Original line number Diff line number Diff line
@@ -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 */