diff options
Diffstat (limited to 'freebsd/sys/netinet/tcp_reass.c')
| -rw-r--r-- | freebsd/sys/netinet/tcp_reass.c | 975 |
1 files changed, 859 insertions, 116 deletions
diff --git a/freebsd/sys/netinet/tcp_reass.c b/freebsd/sys/netinet/tcp_reass.c index dbb61299..4776a808 100644 --- a/freebsd/sys/netinet/tcp_reass.c +++ b/freebsd/sys/netinet/tcp_reass.c @@ -74,15 +74,37 @@ __FBSDID("$FreeBSD$"); #include <netinet/tcp_seq.h> #include <netinet/tcp_timer.h> #include <netinet/tcp_var.h> +#include <netinet/tcp_log_buf.h> +#include <netinet/tcp_hpts.h> #include <netinet6/tcp6_var.h> #include <netinet/tcpip.h> #ifdef TCPDEBUG #include <netinet/tcp_debug.h> #endif /* TCPDEBUG */ +#define TCP_R_LOG_ADD 1 +#define TCP_R_LOG_LIMIT_REACHED 2 +#define TCP_R_LOG_APPEND 3 +#define TCP_R_LOG_PREPEND 4 +#define TCP_R_LOG_REPLACE 5 +#define TCP_R_LOG_MERGE_INTO 6 +#define TCP_R_LOG_NEW_ENTRY 7 +#define TCP_R_LOG_READ 8 +#define TCP_R_LOG_ZERO 9 +#define TCP_R_LOG_DUMP 10 +#define TCP_R_LOG_TRIM 11 + +/* For debugging we want counters and BB logging */ +/* #define TCP_REASS_COUNTERS 1 */ +/* #define TCP_REASS_LOGGING 1 */ + static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, "TCP Segment Reassembly Queue"); +static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats, CTLFLAG_RW, 0, + "TCP Segment Reassembly stats"); + + static int tcp_reass_maxseg = 0; SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, &tcp_reass_maxseg, 0, @@ -93,6 +115,77 @@ SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, &tcp_reass_zone, "Global number of TCP Segments currently in Reassembly Queue"); +static u_int tcp_reass_maxqueuelen = 100; +SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, + &tcp_reass_maxqueuelen, 0, + "Maximum number of TCP Segments per Reassembly Queue"); + +static int tcp_new_limits = 0; +SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN, + &tcp_new_limits, 0, + "Do we use the new limit method we are discussing?"); + +static u_int tcp_reass_queue_guard = 16; +SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN, + &tcp_reass_queue_guard, 16, + "Number of TCP Segments in Reassembly Queue where we flip over to guard mode"); + +#ifdef TCP_REASS_COUNTERS + +counter_u64_t reass_entry; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD, + &reass_entry, "A segment entered reassembly "); + +counter_u64_t reass_path1; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD, + &reass_path1, "Took path 1"); + +counter_u64_t reass_path2; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD, + &reass_path2, "Took path 2"); + +counter_u64_t reass_path3; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD, + &reass_path3, "Took path 3"); + +counter_u64_t reass_path4; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD, + &reass_path4, "Took path 4"); + +counter_u64_t reass_path5; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD, + &reass_path5, "Took path 5"); + +counter_u64_t reass_path6; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD, + &reass_path6, "Took path 6"); + +counter_u64_t reass_path7; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD, + &reass_path7, "Took path 7"); + +counter_u64_t reass_fullwalk; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD, + &reass_fullwalk, "Took a full walk "); + +counter_u64_t reass_nospace; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD, + &reass_nospace, "Had no mbuf capacity "); + +counter_u64_t merge_fwd; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD, + &merge_fwd, "Ran merge fwd"); + +counter_u64_t merge_into; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD, + &merge_into, "Ran merge into"); + +counter_u64_t tcp_zero_input; +SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD, + &tcp_zero_input, "The reassembly buffer saw a zero len segment etc"); + +#endif + /* Initialize TCP reassembly queue */ static void tcp_reass_zone_change(void *tag) @@ -104,6 +197,77 @@ tcp_reass_zone_change(void *tag) tcp_reass_maxseg); } +#ifdef TCP_REASS_LOGGING + +static void +tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p, + tcp_seq seq, int len, uint8_t action, int instance) +{ + uint32_t cts; + struct timeval tv; + + if (tp->t_logstate != TCP_LOG_STATE_OFF) { + union tcp_log_stackspecific log; + + memset(&log, 0, sizeof(log)); + cts = tcp_get_usecs(&tv); + log.u_bbr.flex1 = seq; + log.u_bbr.cur_del_rate = (uint64_t)q; + log.u_bbr.delRate = (uint64_t)p; + if (q != NULL) { + log.u_bbr.flex2 = q->tqe_start; + log.u_bbr.flex3 = q->tqe_len; + log.u_bbr.flex4 = q->tqe_mbuf_cnt; + log.u_bbr.hptsi_gain = q->tqe_flags; + } + if (p != NULL) { + log.u_bbr.flex5 = p->tqe_start; + log.u_bbr.pkts_out = p->tqe_len; + log.u_bbr.epoch = p->tqe_mbuf_cnt; + log.u_bbr.cwnd_gain = p->tqe_flags; + } + log.u_bbr.flex6 = tp->t_segqmbuflen; + log.u_bbr.flex7 = instance; + log.u_bbr.flex8 = action; + log.u_bbr.timeStamp = cts; + TCP_LOG_EVENTP(tp, NULL, + &tp->t_inpcb->inp_socket->so_rcv, + &tp->t_inpcb->inp_socket->so_snd, + TCP_LOG_REASS, 0, + len, &log, false, &tv); + } +} + +static void +tcp_reass_log_dump(struct tcpcb *tp) +{ + struct tseg_qent *q; + + if (tp->t_logstate != TCP_LOG_STATE_OFF) { + TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { + tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0); + } + }; +} + +static void +tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m, + int logval, struct tseg_qent *q) +{ + int cnt; + struct mbuf *t; + + cnt = 0; + t = m; + while (t) { + cnt += t->m_len; + t = t->m_next; + } + tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt); +} + +#endif + void tcp_reass_global_init(void) { @@ -116,8 +280,24 @@ tcp_reass_global_init(void) /* Set the zone limit and read back the effective value. */ tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, tcp_reass_maxseg); +#ifdef TCP_REASS_COUNTERS + reass_path1 = counter_u64_alloc(M_WAITOK); + reass_path2 = counter_u64_alloc(M_WAITOK); + reass_path3 = counter_u64_alloc(M_WAITOK); + reass_path4 = counter_u64_alloc(M_WAITOK); + reass_path5 = counter_u64_alloc(M_WAITOK); + reass_path6 = counter_u64_alloc(M_WAITOK); + reass_path7 = counter_u64_alloc(M_WAITOK); + reass_fullwalk = counter_u64_alloc(M_WAITOK); + reass_nospace = counter_u64_alloc(M_WAITOK); + reass_entry = counter_u64_alloc(M_WAITOK); + merge_fwd = counter_u64_alloc(M_WAITOK); + merge_into = counter_u64_alloc(M_WAITOK); + tcp_zero_input = counter_u64_alloc(M_WAITOK); +#endif EVENTHANDLER_REGISTER(nmbclusters_change, tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); + } void @@ -127,32 +307,237 @@ tcp_reass_flush(struct tcpcb *tp) INP_WLOCK_ASSERT(tp->t_inpcb); - while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) { - LIST_REMOVE(qe, tqe_q); + while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { + TAILQ_REMOVE(&tp->t_segq, qe, tqe_q); m_freem(qe->tqe_m); uma_zfree(tcp_reass_zone, qe); tp->t_segqlen--; } - + tp->t_segqmbuflen = 0; KASSERT((tp->t_segqlen == 0), ("TCP reass queue %p segment count is %d instead of 0 after flush.", tp, tp->t_segqlen)); } +static void +tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last, + struct mbuf *m, struct tcphdr *th, int tlen, + struct mbuf *mlast, int lenofoh) +{ + +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0); +#endif + last->tqe_len += tlen; + last->tqe_m->m_pkthdr.len += tlen; + /* Preserve the FIN bit if its there */ + last->tqe_flags |= (th->th_flags & TH_FIN); + last->tqe_last->m_next = m; + last->tqe_last = mlast; + last->tqe_mbuf_cnt += lenofoh; + tp->t_rcvoopack++; + TCPSTAT_INC(tcps_rcvoopack); + TCPSTAT_ADD(tcps_rcvoobyte, tlen); +#ifdef TCP_REASS_LOGGING + tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m, + TCP_R_LOG_APPEND, + last); +#endif +} + +static void +tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th, + int tlen, struct mbuf *mlast, int lenofoh) +{ + int i; + +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0); +#endif + if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) { + /* The new data overlaps into the old */ + i = (th->th_seq + tlen) - first->tqe_start; +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1); +#endif + m_adj(first->tqe_m, i); + first->tqe_len -= i; + first->tqe_start += i; + } + /* Ok now setup our chain to point to the old first */ + mlast->m_next = first->tqe_m; + first->tqe_m = m; + first->tqe_len += tlen; + first->tqe_start = th->th_seq; + first->tqe_m->m_pkthdr.len = first->tqe_len; + first->tqe_mbuf_cnt += lenofoh; + tp->t_rcvoopack++; + TCPSTAT_INC(tcps_rcvoopack); + TCPSTAT_ADD(tcps_rcvoobyte, tlen); +#ifdef TCP_REASS_LOGGING + tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m, + TCP_R_LOG_PREPEND, + first); +#endif +} + +static void +tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m, + tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint8_t flags) +{ + /* + * Free the data in q, and replace + * it with the new segment. + */ + int len_dif; + +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0); +#endif + m_freem(q->tqe_m); + KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, + ("Tp:%p seg queue goes negative", tp)); + tp->t_segqmbuflen -= q->tqe_mbuf_cnt; + q->tqe_mbuf_cnt = mbufoh; + q->tqe_m = m; + q->tqe_last = mlast; + q->tqe_start = seq; + if (len > q->tqe_len) + len_dif = len - q->tqe_len; + else + len_dif = 0; + tp->t_rcvoopack++; + TCPSTAT_INC(tcps_rcvoopack); + TCPSTAT_ADD(tcps_rcvoobyte, len_dif); + q->tqe_len = len; + q->tqe_flags = (flags & TH_FIN); + q->tqe_m->m_pkthdr.len = q->tqe_len; + tp->t_segqmbuflen += mbufoh; + +} + +static void +tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent, + struct tseg_qent *q) +{ + /* + * Merge q into ent and free q from the list. + */ +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0); +#endif +#ifdef TCP_REASS_COUNTERS + counter_u64_add(merge_into, 1); +#endif + ent->tqe_last->m_next = q->tqe_m; + ent->tqe_last = q->tqe_last; + ent->tqe_len += q->tqe_len; + ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt; + ent->tqe_m->m_pkthdr.len += q->tqe_len; + ent->tqe_flags |= (q->tqe_flags & TH_FIN); + TAILQ_REMOVE(&tp->t_segq, q, tqe_q); + uma_zfree(tcp_reass_zone, q); + tp->t_segqlen--; + +} + +static void +tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent) +{ + struct tseg_qent *q, *qtmp; + int i; + tcp_seq max; + /* + * Given an entry merge forward anyplace + * that ent overlaps forward. + */ + + max = ent->tqe_start + ent->tqe_len; + q = TAILQ_NEXT(ent, tqe_q); + if (q == NULL) { + /* Nothing left */ + return; + } + TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) { + if (SEQ_GT(q->tqe_start, max)) { + /* Beyond q */ + break; + } + /* We have some or all that are overlapping */ + if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) { + /* It consumes it all */ + tp->t_segqmbuflen -= q->tqe_mbuf_cnt; + m_freem(q->tqe_m); + TAILQ_REMOVE(&tp->t_segq, q, tqe_q); + uma_zfree(tcp_reass_zone, q); + tp->t_segqlen--; + continue; + } + /* + * Trim the q entry to dovetail to this one + * and then merge q into ent updating max + * in the process. + */ + i = max - q->tqe_start; +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2); +#endif + m_adj(q->tqe_m, i); + q->tqe_len -= i; + q->tqe_start += i; + tcp_reass_merge_into(tp, ent, q); + max = ent->tqe_start + ent->tqe_len; + } +#ifdef TCP_REASS_COUNTERS + counter_u64_add(merge_fwd, 1); +#endif +} + +static int +tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast) +{ + int len = MSIZE; + + if (m->m_flags & M_EXT) + len += m->m_ext.ext_size; + while (m->m_next != NULL) { + m = m->m_next; + len += MSIZE; + if (m->m_flags & M_EXT) + len += m->m_ext.ext_size; + } + *mlast = m; + return (len); +} + + +/* + * NOTE!!! the new tcp-reassembly code *must not* use + * m_adj() with a negative index. That alters the chain + * of mbufs (by possibly chopping trailing mbufs). At + * the front of tcp_reass we count the mbuf overhead + * and setup the tail pointer. If we use m_adj(m, -5) + * we could corrupt the tail pointer. Currently the + * code only uses m_adj(m, postive-num). If this + * changes appropriate changes to update mlast would + * be needed. + */ int -tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) +tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start, + int *tlenp, struct mbuf *m) { - struct tseg_qent *q; + struct tseg_qent *q, *last, *first; struct tseg_qent *p = NULL; - struct tseg_qent *nq; + struct tseg_qent *nq = NULL; struct tseg_qent *te = NULL; + struct tseg_qent tqs; + struct mbuf *mlast = NULL; + struct sockbuf *sb; struct socket *so = tp->t_inpcb->inp_socket; char *s = NULL; - int flags; - struct tseg_qent tqs; + int flags, i, lenofoh; INP_WLOCK_ASSERT(tp->t_inpcb); - /* * XXX: tcp_reass() is rather inefficient with its data structures * and should be rewritten (see NetBSD for optimizations). @@ -164,149 +549,475 @@ tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) */ if (th == NULL) goto present; - + KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), + ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)", + th, tp)); +#ifdef TCP_REASS_LOGGING + tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL); +#endif +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_entry, 1); +#endif /* - * Limit the number of segments that can be queued to reduce the - * potential for mbuf exhaustion. For best performance, we want to be - * able to queue a full window's worth of segments. The size of the - * socket receive buffer determines our advertised window and grows - * automatically when socket buffer autotuning is enabled. Use it as the - * basis for our queue limit. - * Always let the missing segment through which caused this queue. - * NB: Access to the socket buffer is left intentionally unlocked as we - * can tolerate stale information here. - * - * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat - * should work but causes packets to be dropped when they shouldn't. - * Investigate why and re-evaluate the below limit after the behaviour - * is understood. + * Check for zero length data. + */ + if ((*tlenp == 0) && ((th->th_flags & TH_FIN) == 0)) { + /* + * A zero length segment does no + * one any good. We could check + * the rcv_nxt <-> rcv_wnd but thats + * already done for us by the caller. + */ +#ifdef TCP_REASS_COUNTERS + counter_u64_add(tcp_zero_input, 1); +#endif + m_freem(m); +#ifdef TCP_REASS_LOGGING + tcp_reass_log_dump(tp); +#endif + return (0); + } + /* + * Will it fit? */ - if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && - tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) { + lenofoh = tcp_reass_overhead_of_chain(m, &mlast); + sb = &tp->t_inpcb->inp_socket->so_rcv; + if ((sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) { + /* No room */ TCPSTAT_INC(tcps_rcvreassfull); - *tlenp = 0; - if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { - log(LOG_DEBUG, "%s; %s: queue limit reached, " - "segment dropped\n", s, __func__); - free(s, M_TCPLOG); - } +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_nospace, 1); +#endif +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0); +#endif m_freem(m); + *tlenp = 0; +#ifdef TCP_REASS_LOGGING + tcp_reass_log_dump(tp); +#endif return (0); } - /* - * Allocate a new queue entry. If we can't, or hit the zone limit - * just drop the pkt. - * - * Use a temporary structure on the stack for the missing segment - * when the zone is exhausted. Otherwise we may get stuck. + * First lets deal with two common cases, the + * segment appends to the back of our collected + * segments. Or the segment is the next in line. */ - te = uma_zalloc(tcp_reass_zone, M_NOWAIT); - if (te == NULL) { - if (th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) { - TCPSTAT_INC(tcps_rcvmemdrop); - m_freem(m); + last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q); + if (last != NULL) { + if ((th->th_flags & TH_FIN) && + SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) { + /* + * Someone is trying to game us, dump + * the segment. + */ *tlenp = 0; - if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, - NULL))) { - log(LOG_DEBUG, "%s; %s: global zone limit " - "reached, segment dropped\n", s, __func__); - free(s, M_TCPLOG); + m_freem(m); + return (0); + } + if ((SEQ_GEQ(th->th_seq, last->tqe_start)) && + (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) { + /* Common case, trailing segment is added */ + /** + * +--last + * v + * reassembly buffer |---| |---| |---| + * new segment |---| + */ +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_path1, 1); +#endif + if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) { + i = (last->tqe_start + last->tqe_len) - th->th_seq; + if (i < *tlenp) { +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3); + th->th_seq += i; +#endif + m_adj(m, i); + *tlenp -= i; + } else { + /* Complete overlap */ + TCPSTAT_INC(tcps_rcvduppack); + TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); + m_freem(m); + *tlenp = last->tqe_len; + *seq_start = last->tqe_start; + return (0); + } + } + if (last->tqe_flags & TH_FIN) { + /* + * We have data after the FIN on the last? + */ + *tlenp = 0; + m_freem(m); + return(0); } + tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh); + tp->t_segqmbuflen += lenofoh; + *seq_start = last->tqe_start; + *tlenp = last->tqe_len; return (0); - } else { - bzero(&tqs, sizeof(struct tseg_qent)); - te = &tqs; - if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, - NULL))) { - log(LOG_DEBUG, - "%s; %s: global zone limit reached, using " - "stack for missing segment\n", s, __func__); - free(s, M_TCPLOG); + } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) { + /* + * Second common case, we missed + * another one and have something more + * for the end. + */ + /** + * +--last + * v + * reassembly buffer |---| |---| |---| + * new segment |---| + */ + if (last->tqe_flags & TH_FIN) { + /* + * We have data after the FIN on the last? + */ + *tlenp = 0; + m_freem(m); + return(0); } +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_path2, 1); +#endif + p = last; + goto new_entry; } + } else { + /* First segment (it's NULL). */ + goto new_entry; } - tp->t_segqlen++; + first = TAILQ_FIRST(&tp->t_segq); + if (SEQ_LT(th->th_seq, first->tqe_start) && + SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) && + SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) { + /* + * The head of the queue is prepended by this and + * it may be the one I want most. + */ + /** + * first-------+ + * v + * rea: |---| |---| |---| + * new: |---| + * Note the case we do not deal with here is: + * rea= |---| |---| |---| + * new= |----| + * Due to the fact that it could be + * new |--------------------| + * And we might need to merge forward. + */ +#ifdef INVARIANTS + struct mbuf *firstmbuf; +#endif +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_path3, 1); +#endif + if (SEQ_LT(th->th_seq, tp->rcv_nxt)) { + /* + * The resend was even before + * what we have. We need to trim it. + * Note TSNH (it should be trimmed + * before the call to tcp_reass()). + */ +#ifdef INVARIANTS + panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed", + th->th_seq, tp->rcv_nxt, tp); +#else + i = tp->rcv_nxt - th->th_seq; +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4); +#endif + m_adj(m, i); + th->th_seq += i; + *tlenp -= i; +#endif + } +#ifdef INVARIANTS + firstmbuf = first->tqe_m; +#endif + tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh); +#ifdef INVARIANTS + if (firstmbuf == first->tqe_m) { + panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", + m, firstmbuf, first->tqe_m, tp, first); + } else if (first->tqe_m != m) { + panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", + m, firstmbuf, first->tqe_m, tp, first); + } +#endif + tp->t_segqmbuflen += lenofoh; + *seq_start = first->tqe_start; + *tlenp = first->tqe_len; + goto present; + } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) { + /* New segment is before our earliest segment. */ + /** + * first---->+ + * v + * rea= |---| .... + * new" |---| + * + */ + goto new_entry; + } /* * Find a segment which begins after this one does. */ - LIST_FOREACH(q, &tp->t_segq, tqe_q) { - if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_fullwalk, 1); +#endif + TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { + if (SEQ_GT(q->tqe_start, th->th_seq)) break; - p = q; } - - /* - * If there is a preceding segment, it may provide some of - * our data already. If so, drop the data from the incoming - * segment. If it provides all of our data, drop us. + p = TAILQ_PREV(q, tsegqe_head, tqe_q); + /** + * Now is this fit just in-between only? + * i.e.: + * p---+ +----q + * v v + * res= |--| |--| |--| + * nee |-| + */ + if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) && + ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) { + /* Yep no overlap */ + goto new_entry; + } + /** + * If we reach here we have some (possibly all) overlap + * such as: + * res= |--| |--| |--| + * new= |----| + * or new= |-----------------| + * or new= |--------| + * or new= |---| + * or new= |-----------| */ - if (p != NULL) { - int i; + if ((p != NULL) && + (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) { /* conversion to int (in i) handles seq wraparound */ - i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; - if (i > 0) { + +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_path4, 1); +#endif + i = p->tqe_start + p->tqe_len - th->th_seq; + if (i >= 0) { if (i >= *tlenp) { + /** + * prev seg---->+ + * v + * reassembly buffer |---| + * new segment |-| + */ TCPSTAT_INC(tcps_rcvduppack); TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); + *tlenp = p->tqe_len; + *seq_start = p->tqe_start; m_freem(m); - if (te != &tqs) - uma_zfree(tcp_reass_zone, te); - tp->t_segqlen--; /* * Try to present any queued data * at the left window edge to the user. * This is needed after the 3-WHS - * completes. + * completes. Note this probably + * will not work and we will return. */ - goto present; /* ??? */ + return (0); } - m_adj(m, i); - *tlenp -= i; - th->th_seq += i; + if (i > 0) { + /** + * prev seg---->+ + * v + * reassembly buffer |---| + * new segment |-----| + */ +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_path5, 1); +#endif +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5); +#endif + m_adj(m, i); + *tlenp -= i; + th->th_seq += i; + } + } + if (th->th_seq == (p->tqe_start + p->tqe_len)) { + /* + * If dovetails in with this one + * append it. + */ + /** + * prev seg---->+ + * v + * reassembly buffer |--| |---| + * new segment |--| + * (note: it was trimmed above if it overlapped) + */ + tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh); + tp->t_segqmbuflen += lenofoh; + } else { +#ifdef INVARIANTS + panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p", + th->th_seq, p->tqe_start, p->tqe_len, + p, tp); +#endif + *tlenp = 0; + m_freem(m); + return (0); + } + q = p; + } else { + /* + * The new data runs over the + * top of previously sack'd data (in q). + * It may be partially overlapping, or + * it may overlap the entire segment. + */ +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_path6, 1); +#endif + if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) { + /* It consumes it all */ + /** + * next seg---->+ + * v + * reassembly buffer |--| |---| + * new segment |----------| + */ +#ifdef TCP_REASS_COUNTERS + counter_u64_add(reass_path7, 1); +#endif + tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, th->th_flags); + } else { + /* + * We just need to prepend the data + * to this. It does not overrun + * the end. + */ + /** + * next seg---->+ + * v + * reassembly buffer |--| |---| + * new segment |----------| + */ + tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh); + tp->t_segqmbuflen += lenofoh; } } - tp->t_rcvoopack++; - TCPSTAT_INC(tcps_rcvoopack); - TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); + /* Now does it go further than that? */ + tcp_reass_merge_forward(tp, q); + *seq_start = q->tqe_start; + *tlenp = q->tqe_len; + goto present; - /* - * While we overlap succeeding segments trim them or, - * if they are completely covered, dequeue them. + /* + * When we reach here we can't combine it + * with any existing segment. + * + * Limit the number of segments that can be queued to reduce the + * potential for mbuf exhaustion. For best performance, we want to be + * able to queue a full window's worth of segments. The size of the + * socket receive buffer determines our advertised window and grows + * automatically when socket buffer autotuning is enabled. Use it as the + * basis for our queue limit. + * + * However, allow the user to specify a ceiling for the number of + * segments in each queue. + * + * Always let the missing segment through which caused this queue. + * NB: Access to the socket buffer is left intentionally unlocked as we + * can tolerate stale information here. + * + * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat + * should work but causes packets to be dropped when they shouldn't. + * Investigate why and re-evaluate the below limit after the behaviour + * is understood. */ - while (q) { - int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; - if (i <= 0) - break; - if (i < q->tqe_len) { - q->tqe_th->th_seq += i; - q->tqe_len -= i; - m_adj(q->tqe_m, i); - break; +new_entry: + if (tcp_new_limits) { + if ((tp->t_segqlen > tcp_reass_queue_guard) && + (*tlenp < MSIZE)) { + /* + * This is really a lie, we are not full but + * are getting a segment that is above + * guard threshold. If it is and its below + * a mbuf size (256) we drop it if it + * can't fill in some place. + */ + TCPSTAT_INC(tcps_rcvreassfull); + *tlenp = 0; + if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { + log(LOG_DEBUG, "%s; %s: queue limit reached, " + "segment dropped\n", s, __func__); + free(s, M_TCPLOG); + } + m_freem(m); +#ifdef TCP_REASS_LOGGING + tcp_reass_log_dump(tp); +#endif + return (0); } + } else { - nq = LIST_NEXT(q, tqe_q); - LIST_REMOVE(q, tqe_q); - m_freem(q->tqe_m); - uma_zfree(tcp_reass_zone, q); - tp->t_segqlen--; - q = nq; + if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && + tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, + tcp_reass_maxqueuelen)) { + TCPSTAT_INC(tcps_rcvreassfull); + *tlenp = 0; + if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { + log(LOG_DEBUG, "%s; %s: queue limit reached, " + "segment dropped\n", s, __func__); + free(s, M_TCPLOG); + } + m_freem(m); +#ifdef TCP_REASS_LOGGING + tcp_reass_log_dump(tp); +#endif + return (0); + } } - + /* + * Allocate a new queue entry. If we can't, or hit the zone limit + * just drop the pkt. + */ + te = uma_zalloc(tcp_reass_zone, M_NOWAIT); + if (te == NULL) { + TCPSTAT_INC(tcps_rcvmemdrop); + m_freem(m); + *tlenp = 0; + if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, + NULL))) { + log(LOG_DEBUG, "%s; %s: global zone limit " + "reached, segment dropped\n", s, __func__); + free(s, M_TCPLOG); + } + return (0); + } + tp->t_segqlen++; + tp->t_rcvoopack++; + TCPSTAT_INC(tcps_rcvoopack); + TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); /* Insert the new segment queue entry into place. */ te->tqe_m = m; - te->tqe_th = th; + te->tqe_flags = th->th_flags; te->tqe_len = *tlenp; - + te->tqe_start = th->th_seq; + te->tqe_last = mlast; + te->tqe_mbuf_cnt = lenofoh; + tp->t_segqmbuflen += te->tqe_mbuf_cnt; if (p == NULL) { - LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); + TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q); } else { - KASSERT(te != &tqs, ("%s: temporary stack based entry not " - "first element in queue", __func__)); - LIST_INSERT_AFTER(p, te, tqe_q); + TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q); } - +#ifdef TCP_REASS_LOGGING + tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te); +#endif present: /* * Present data to user, advancing rcv_nxt through @@ -314,24 +1025,56 @@ present: */ if (!TCPS_HAVEESTABLISHED(tp->t_state)) return (0); - q = LIST_FIRST(&tp->t_segq); - if (!q || q->tqe_th->th_seq != tp->rcv_nxt) + q = TAILQ_FIRST(&tp->t_segq); + KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt), + ("Reassembly queue for %p has stale entry at head", tp)); + if (!q || q->tqe_start != tp->rcv_nxt) { +#ifdef TCP_REASS_LOGGING + tcp_reass_log_dump(tp); +#endif return (0); + } SOCKBUF_LOCK(&so->so_rcv); do { tp->rcv_nxt += q->tqe_len; - flags = q->tqe_th->th_flags & TH_FIN; - nq = LIST_NEXT(q, tqe_q); - LIST_REMOVE(q, tqe_q); - if (so->so_rcv.sb_state & SBS_CANTRCVMORE) + flags = q->tqe_flags & TH_FIN; + nq = TAILQ_NEXT(q, tqe_q); + TAILQ_REMOVE(&tp->t_segq, q, tqe_q); + if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { m_freem(q->tqe_m); - else + } else { +#ifdef TCP_REASS_LOGGING + tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q); + tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1); +#endif sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); - if (q != &tqs) + } +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2); +#endif + KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, + ("tp:%p seg queue goes negative", tp)); + tp->t_segqmbuflen -= q->tqe_mbuf_cnt; + if (q != &tqs) uma_zfree(tcp_reass_zone, q); tp->t_segqlen--; q = nq; - } while (q && q->tqe_th->th_seq == tp->rcv_nxt); + } while (q && q->tqe_start == tp->rcv_nxt); + if (TAILQ_EMPTY(&tp->t_segq) && + (tp->t_segqmbuflen != 0)) { +#ifdef INVARIANTS + panic("tp:%p segq:%p len:%d queue empty", + tp, &tp->t_segq, tp->t_segqmbuflen); +#else +#ifdef TCP_REASS_LOGGING + tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0); +#endif + tp->t_segqmbuflen = 0; +#endif + } +#ifdef TCP_REASS_LOGGING + tcp_reass_log_dump(tp); +#endif sorwakeup_locked(so); return (flags); } |