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>
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@ -141,7 +141,8 @@ rx_ccid = 2
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Default CCID for the receiver-sender half-connection; see tx_ccid.
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seq_window = 100
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The initial sequence window (sec. 7.5.2).
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The initial sequence window (sec. 7.5.2) of the sender. This influences
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the local ackno validity and the remote seqno validity windows (7.5.1).
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tx_qlen = 5
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The size of the transmit buffer in packets. A value of 0 corresponds
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@ -363,19 +363,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
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/* FIXME: for now we're default to 1 but it should really be 0 */
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#define DCCPF_INITIAL_SEND_NDP_COUNT 1
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/**
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* struct dccp_minisock - Minimal DCCP connection representation
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*
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* Will be used to pass the state from dccp_request_sock to dccp_sock.
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*
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* @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
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*/
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struct dccp_minisock {
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__u64 dccpms_sequence_window;
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};
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extern void dccp_minisock_init(struct dccp_minisock *dmsk);
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/**
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* struct dccp_request_sock - represent DCCP-specific connection request
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* @dreq_inet_rsk: structure inherited from
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@ -464,13 +451,14 @@ struct dccp_ackvec;
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* @dccps_timestamp_time - time of receiving latest @dccps_timestamp_echo
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* @dccps_l_ack_ratio - feature-local Ack Ratio
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* @dccps_r_ack_ratio - feature-remote Ack Ratio
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* @dccps_l_seq_win - local Sequence Window (influences ack number validity)
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* @dccps_r_seq_win - remote Sequence Window (influences seq number validity)
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* @dccps_pcslen - sender partial checksum coverage (via sockopt)
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* @dccps_pcrlen - receiver partial checksum coverage (via sockopt)
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* @dccps_send_ndp_count - local Send NDP Count feature (7.7.2)
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* @dccps_ndp_count - number of Non Data Packets since last data packet
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* @dccps_mss_cache - current value of MSS (path MTU minus header sizes)
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* @dccps_rate_last - timestamp for rate-limiting DCCP-Sync (RFC 4340, 7.5.4)
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* @dccps_minisock - associated minisock (accessed via dccp_msk)
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* @dccps_featneg - tracks feature-negotiation state (mostly during handshake)
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* @dccps_hc_rx_ackvec - rx half connection ack vector
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* @dccps_hc_rx_ccid - CCID used for the receiver (or receiving half-connection)
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@ -504,12 +492,13 @@ struct dccp_sock {
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__u32 dccps_timestamp_time;
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__u16 dccps_l_ack_ratio;
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__u16 dccps_r_ack_ratio;
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__u64 dccps_l_seq_win:48;
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__u64 dccps_r_seq_win:48;
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__u8 dccps_pcslen:4;
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__u8 dccps_pcrlen:4;
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__u8 dccps_send_ndp_count:1;
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__u64 dccps_ndp_count:48;
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unsigned long dccps_rate_last;
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struct dccp_minisock dccps_minisock;
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struct list_head dccps_featneg;
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struct dccp_ackvec *dccps_hc_rx_ackvec;
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struct ccid *dccps_hc_rx_ccid;
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@ -527,11 +516,6 @@ static inline struct dccp_sock *dccp_sk(const struct sock *sk)
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return (struct dccp_sock *)sk;
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}
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static inline struct dccp_minisock *dccp_msk(const struct sock *sk)
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{
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return (struct dccp_minisock *)&dccp_sk(sk)->dccps_minisock;
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}
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static inline const char *dccp_role(const struct sock *sk)
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{
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switch (dccp_sk(sk)->dccps_role) {
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@ -409,23 +409,21 @@ static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
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static inline void dccp_update_gsr(struct sock *sk, u64 seq)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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const struct dccp_minisock *dmsk = dccp_msk(sk);
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dp->dccps_gsr = seq;
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dccp_set_seqno(&dp->dccps_swl,
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dp->dccps_gsr + 1 - (dmsk->dccpms_sequence_window / 4));
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dccp_set_seqno(&dp->dccps_swh,
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dp->dccps_gsr + (3 * dmsk->dccpms_sequence_window) / 4);
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/* Sequence validity window depends on remote Sequence Window (7.5.1) */
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dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
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dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);
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}
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static inline void dccp_update_gss(struct sock *sk, u64 seq)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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dp->dccps_awh = dp->dccps_gss = seq;
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dccp_set_seqno(&dp->dccps_awl,
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(dp->dccps_gss -
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dccp_msk(sk)->dccpms_sequence_window + 1));
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dp->dccps_gss = seq;
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/* Ack validity window depends on local Sequence Window value (7.5.1) */
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dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);
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dp->dccps_awh = dp->dccps_gss;
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}
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static inline int dccp_ack_pending(const struct sock *sk)
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@ -52,8 +52,17 @@ static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
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static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
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{
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if (!rx)
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dccp_msk(sk)->dccpms_sequence_window = seq_win;
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struct dccp_sock *dp = dccp_sk(sk);
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if (rx) {
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dp->dccps_r_seq_win = seq_win;
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/* propagate changes to update SWL/SWH */
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dccp_update_gsr(sk, dp->dccps_gsr);
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} else {
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dp->dccps_l_seq_win = seq_win;
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/* propagate changes to update AWL */
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dccp_update_gss(sk, dp->dccps_gss);
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}
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return 0;
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}
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@ -42,11 +42,6 @@ struct inet_timewait_death_row dccp_death_row = {
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EXPORT_SYMBOL_GPL(dccp_death_row);
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void dccp_minisock_init(struct dccp_minisock *dmsk)
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{
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dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
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}
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void dccp_time_wait(struct sock *sk, int state, int timeo)
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{
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struct inet_timewait_sock *tw = NULL;
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@ -110,7 +105,6 @@ struct sock *dccp_create_openreq_child(struct sock *sk,
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struct dccp_request_sock *dreq = dccp_rsk(req);
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struct inet_connection_sock *newicsk = inet_csk(newsk);
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struct dccp_sock *newdp = dccp_sk(newsk);
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struct dccp_minisock *newdmsk = dccp_msk(newsk);
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newdp->dccps_role = DCCP_ROLE_SERVER;
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newdp->dccps_hc_rx_ackvec = NULL;
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@ -128,10 +122,6 @@ struct sock *dccp_create_openreq_child(struct sock *sk,
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* Initialize S.GAR := S.ISS
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* Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
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*/
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/* See dccp_v4_conn_request */
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newdmsk->dccpms_sequence_window = req->rcv_wnd;
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newdp->dccps_gar = newdp->dccps_iss = dreq->dreq_iss;
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dccp_update_gss(newsk, dreq->dreq_iss);
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@ -289,7 +279,6 @@ int dccp_reqsk_init(struct request_sock *req,
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inet_rsk(req)->rmt_port = dccp_hdr(skb)->dccph_sport;
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inet_rsk(req)->acked = 0;
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req->rcv_wnd = sysctl_dccp_feat_sequence_window;
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dreq->dreq_timestamp_echo = 0;
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/* inherit feature negotiation options from listening socket */
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@ -180,8 +180,6 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
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struct dccp_sock *dp = dccp_sk(sk);
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struct inet_connection_sock *icsk = inet_csk(sk);
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dccp_minisock_init(&dp->dccps_minisock);
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icsk->icsk_rto = DCCP_TIMEOUT_INIT;
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icsk->icsk_syn_retries = sysctl_dccp_request_retries;
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sk->sk_state = DCCP_CLOSED;
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