Receiver side DSACK implemenation.
This adds initial support for RFC 2883. Submitted by: Richard Scheffenegger Reviewed by: rrs@ Differential Revision: https://reviews.freebsd.org/D19334
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=347382
@ -2258,6 +2258,17 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
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TCPSTAT_INC(tcps_rcvpartduppack);
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TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop);
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}
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/*
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* DSACK - add SACK block for dropped range
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*/
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if (tp->t_flags & TF_SACK_PERMIT) {
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tcp_update_sack_list(tp, th->th_seq, th->th_seq+tlen);
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/*
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* ACK now, as the next in-sequence segment
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* will clear the DSACK block again
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*/
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tp->t_flags |= TF_ACKNOW;
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}
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drop_hdrlen += todrop; /* drop from the top afterwards */
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th->th_seq += todrop;
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tlen -= todrop;
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@ -2986,6 +2997,8 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
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if ((tlen || (thflags & TH_FIN) || tfo_syn) &&
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TCPS_HAVERCVDFIN(tp->t_state) == 0) {
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tcp_seq save_start = th->th_seq;
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tcp_seq save_rnxt = tp->rcv_nxt;
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int save_tlen = tlen;
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m_adj(m, drop_hdrlen); /* delayed header drop */
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/*
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* Insert segment which includes th into TCP reassembly queue
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@ -3025,11 +3038,28 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
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* m_adj() doesn't actually frees any mbufs
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* when trimming from the head.
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*/
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thflags = tcp_reass(tp, th, &save_start, &tlen, m);
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tcp_seq temp = save_start;
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thflags = tcp_reass(tp, th, &temp, &tlen, m);
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tp->t_flags |= TF_ACKNOW;
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}
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if (tlen > 0 && (tp->t_flags & TF_SACK_PERMIT))
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if (tp->t_flags & TF_SACK_PERMIT) {
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if (((tlen == 0) && (save_tlen > 0) &&
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(SEQ_LT(save_start, save_rnxt)))) {
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// DSACK actually handled in the fastpath above
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tcp_update_sack_list(tp, save_start, save_start + save_tlen);
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} else
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if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) {
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// cleaning sackblks by using zero length update
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tcp_update_sack_list(tp, save_start, save_start);
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} else
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if ((tlen > 0) && (tlen >= save_tlen)) {
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// update of sackblks
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tcp_update_sack_list(tp, save_start, save_start + save_tlen);
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} else
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if (tlen > 0) {
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tcp_update_sack_list(tp, save_start, save_start+tlen);
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}
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}
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#if 0
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/*
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* Note the amount of data that peer has sent into
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@ -168,7 +168,7 @@ tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end)
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INP_WLOCK_ASSERT(tp->t_inpcb);
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/* Check arguments. */
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KASSERT(SEQ_LT(rcv_start, rcv_end), ("rcv_start < rcv_end"));
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KASSERT(SEQ_LEQ(rcv_start, rcv_end), ("rcv_start <= rcv_end"));
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/* SACK block for the received segment. */
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head_blk.start = rcv_start;
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@ -193,11 +193,53 @@ tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end)
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* Merge this SACK block into head_blk. This SACK
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* block itself will be discarded.
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*/
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if (SEQ_GT(head_blk.start, start))
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/*
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* |-|
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* |---| merge
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*
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* |-|
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* |---| merge
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*
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* |-----|
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* |-| DSACK smaller
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*
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* |-|
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* |-----| DSACK smaller
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*/
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if (head_blk.start == end)
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head_blk.start = start;
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if (SEQ_LT(head_blk.end, end))
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else if (head_blk.end == start)
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head_blk.end = end;
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else {
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if (SEQ_LT(head_blk.start, start)) {
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tcp_seq temp = start;
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start = head_blk.start;
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head_blk.start = temp;
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}
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if (SEQ_GT(head_blk.end, end)) {
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tcp_seq temp = end;
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end = head_blk.end;
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head_blk.end = temp;
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}
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if ((head_blk.start != start) ||
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(head_blk.end != end)) {
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if ((num_saved >= 1) &&
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SEQ_GEQ(saved_blks[num_saved-1].start, start) &&
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SEQ_LEQ(saved_blks[num_saved-1].end, end))
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num_saved--;
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saved_blks[num_saved].start = start;
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saved_blks[num_saved].end = end;
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num_saved++;
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}
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}
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} else {
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/*
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* This block supercedes the prior block
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*/
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if ((num_saved >= 1) &&
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SEQ_GEQ(saved_blks[num_saved-1].start, start) &&
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SEQ_LEQ(saved_blks[num_saved-1].end, end))
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num_saved--;
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/*
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* Save this SACK block.
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*/
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@ -211,7 +253,7 @@ tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end)
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* Update SACK list in tp->sackblks[].
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*/
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num_head = 0;
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if (SEQ_GT(head_blk.start, tp->rcv_nxt)) {
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if (SEQ_LT(rcv_start, rcv_end)) {
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/*
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* The received data segment is an out-of-order segment. Put
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* head_blk at the top of SACK list.
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