X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/blobdiff_plain/4aed14e3ebfbde3ff796efe7c427a1a8573ea0a5..05db08ca40dcf52f15be693f25a96a593409f690:/usr/src/sys/netinet/tcp_input.c diff --git a/usr/src/sys/netinet/tcp_input.c b/usr/src/sys/netinet/tcp_input.c index 22200f05df..109b7902ac 100644 --- a/usr/src/sys/netinet/tcp_input.c +++ b/usr/src/sys/netinet/tcp_input.c @@ -1,28 +1,168 @@ -/* tcp_input.c 1.39 81/12/12 */ - -#include "../h/param.h" -#include "../h/systm.h" -#include "../h/mbuf.h" -#include "../h/protosw.h" -#include "../h/socket.h" -#include "../h/socketvar.h" -#include "../net/in.h" -#include "../net/in_pcb.h" -#include "../net/in_systm.h" +/* + * Copyright (c) 1982, 1986 Regents of the University of California. + * All rights reserved. The Berkeley software License Agreement + * specifies the terms and conditions for redistribution. + * + * @(#)tcp_input.c 7.12 (Berkeley) %G% + */ + +#include "param.h" +#include "systm.h" +#include "mbuf.h" +#include "protosw.h" +#include "socket.h" +#include "socketvar.h" +#include "errno.h" + #include "../net/if.h" -#include "../net/ip.h" -#include "../net/ip_var.h" -#include "../net/tcp.h" -#define TCPSTATES -#include "../net/tcp_fsm.h" -#include "../net/tcp_seq.h" -#include "../net/tcp_timer.h" -#include "../net/tcp_var.h" -#include "../net/tcpip.h" -#include "../errno.h" +#include "../net/route.h" + +#include "in.h" +#include "in_pcb.h" +#include "in_systm.h" +#include "ip.h" +#include "ip_var.h" +#include "tcp.h" +#include "tcp_fsm.h" +#include "tcp_seq.h" +#include "tcp_timer.h" +#include "tcp_var.h" +#include "tcpip.h" +#include "tcp_debug.h" +int tcpprintfs = 0; int tcpcksum = 1; -struct sockaddr_in tcp_in = { AF_INET }; +int tcprexmtthresh = 3; +struct tcpiphdr tcp_saveti; +extern tcpnodelack; + +struct tcpcb *tcp_newtcpcb(); + +/* + * Insert segment ti into reassembly queue of tcp with + * control block tp. Return TH_FIN if reassembly now includes + * a segment with FIN. The macro form does the common case inline + * (segment is the next to be received on an established connection, + * and the queue is empty), avoiding linkage into and removal + * from the queue and repetition of various conversions. + */ +#define TCP_REASS(tp, ti, m, so, flags) { \ + if ((ti)->ti_seq == (tp)->rcv_nxt && \ + (tp)->seg_next == (struct tcpiphdr *)(tp) && \ + (tp)->t_state == TCPS_ESTABLISHED) { \ + (tp)->rcv_nxt += (ti)->ti_len; \ + flags = (ti)->ti_flags & TH_FIN; \ + tcpstat.tcps_rcvpack++;\ + tcpstat.tcps_rcvbyte += (ti)->ti_len;\ + sbappend(&(so)->so_rcv, (m)); \ + sorwakeup(so); \ + } else \ + (flags) = tcp_reass((tp), (ti)); \ +} + +tcp_reass(tp, ti) + register struct tcpcb *tp; + register struct tcpiphdr *ti; +{ + register struct tcpiphdr *q; + struct socket *so = tp->t_inpcb->inp_socket; + struct mbuf *m; + int flags; + + /* + * Call with ti==0 after become established to + * force pre-ESTABLISHED data up to user socket. + */ + if (ti == 0) + goto present; + + /* + * Find a segment which begins after this one does. + */ + for (q = tp->seg_next; q != (struct tcpiphdr *)tp; + q = (struct tcpiphdr *)q->ti_next) + if (SEQ_GT(q->ti_seq, ti->ti_seq)) + break; + + /* + * 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. + */ + if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { + register int i; + q = (struct tcpiphdr *)q->ti_prev; + /* conversion to int (in i) handles seq wraparound */ + i = q->ti_seq + q->ti_len - ti->ti_seq; + if (i > 0) { + if (i >= ti->ti_len) { + tcpstat.tcps_rcvduppack++; + tcpstat.tcps_rcvdupbyte += ti->ti_len; + goto drop; + } + m_adj(dtom(ti), i); + ti->ti_len -= i; + ti->ti_seq += i; + } + q = (struct tcpiphdr *)(q->ti_next); + } + tcpstat.tcps_rcvoopack++; + tcpstat.tcps_rcvoobyte += ti->ti_len; + + /* + * While we overlap succeeding segments trim them or, + * if they are completely covered, dequeue them. + */ + while (q != (struct tcpiphdr *)tp) { + register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; + if (i <= 0) + break; + if (i < q->ti_len) { + q->ti_seq += i; + q->ti_len -= i; + m_adj(dtom(q), i); + break; + } + q = (struct tcpiphdr *)q->ti_next; + m = dtom(q->ti_prev); + remque(q->ti_prev); + m_freem(m); + } + + /* + * Stick new segment in its place. + */ + insque(ti, q->ti_prev); + +present: + /* + * Present data to user, advancing rcv_nxt through + * completed sequence space. + */ + if (TCPS_HAVERCVDSYN(tp->t_state) == 0) + return (0); + ti = tp->seg_next; + if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) + return (0); + if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len) + return (0); + do { + tp->rcv_nxt += ti->ti_len; + flags = ti->ti_flags & TH_FIN; + remque(ti); + m = dtom(ti); + ti = (struct tcpiphdr *)ti->ti_next; + if (so->so_state & SS_CANTRCVMORE) + m_freem(m); + else + sbappend(&so->so_rcv, m); + } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); + sorwakeup(so); + return (flags); +drop: + m_freem(dtom(ti)); + return (0); +} /* * TCP input routine, follows pages 65-76 of the @@ -34,13 +174,18 @@ tcp_input(m0) register struct tcpiphdr *ti; struct inpcb *inp; register struct mbuf *m; + struct mbuf *om = 0; int len, tlen, off; - register struct tcpcb *tp; + register struct tcpcb *tp = 0; register int tiflags; struct socket *so; - int todrop, acked; + int todrop, acked, ourfinisacked, needoutput = 0; + short ostate; + struct in_addr laddr; + int dropsocket = 0; + int iss = 0; -COUNT(TCP_INPUT); + tcpstat.tcps_rcvtotal++; /* * Get IP and TCP header together in first mbuf. * Note: IP leaves IP header in first mbuf. @@ -49,12 +194,10 @@ COUNT(TCP_INPUT); ti = mtod(m, struct tcpiphdr *); if (((struct ip *)ti)->ip_hl > (sizeof (struct ip) >> 2)) ip_stripoptions((struct ip *)ti, (struct mbuf *)0); - if (m->m_len < sizeof (struct tcpiphdr)) { -printf("m->m_len %d\n", m->m_len); - if (m_pullup(m, sizeof (struct tcpiphdr)) == 0) { -printf("tcp_input: header drop\n"); - tcpstat.tcps_hdrops++; - goto drop; + if (m->m_off > MMAXOFF || m->m_len < sizeof (struct tcpiphdr)) { + if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { + tcpstat.tcps_rcvshort++; + return; } ti = mtod(m, struct tcpiphdr *); } @@ -68,34 +211,55 @@ printf("tcp_input: header drop\n"); ti->ti_next = ti->ti_prev = 0; ti->ti_x1 = 0; ti->ti_len = (u_short)tlen; -#if vax - ti->ti_len = htons(ti->ti_len); -#endif + ti->ti_len = htons((u_short)ti->ti_len); if (ti->ti_sum = in_cksum(m, len)) { - tcpstat.tcps_badsum++; - printf("tcp cksum %x\n", ti->ti_sum); + if (tcpprintfs) + printf("tcp sum: src %x\n", ti->ti_src); + tcpstat.tcps_rcvbadsum++; goto drop; } } /* * Check that TCP offset makes sense, - * process TCP options and adjust length. + * pull out TCP options and adjust length. */ off = ti->ti_off << 2; if (off < sizeof (struct tcphdr) || off > tlen) { -printf("tcp_input: bad offset\n"); - tcpstat.tcps_badoff++; + if (tcpprintfs) + printf("tcp off: src %x off %d\n", ti->ti_src, off); + tcpstat.tcps_rcvbadoff++; goto drop; } - ti->ti_len = tlen - off; -#if 0 - if (off > sizeof (struct tcphdr)) - tcp_options(ti); -#endif + tlen -= off; + ti->ti_len = tlen; + if (off > sizeof (struct tcphdr)) { + if (m->m_len < sizeof(struct ip) + off) { + if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { + tcpstat.tcps_rcvshort++; + return; + } + ti = mtod(m, struct tcpiphdr *); + } + om = m_get(M_DONTWAIT, MT_DATA); + if (om == 0) + goto drop; + om->m_len = off - sizeof (struct tcphdr); + { caddr_t op = mtod(m, caddr_t) + sizeof (struct tcpiphdr); + bcopy(op, mtod(om, caddr_t), (unsigned)om->m_len); + m->m_len -= om->m_len; + bcopy(op+om->m_len, op, + (unsigned)(m->m_len-sizeof (struct tcpiphdr))); + } + } tiflags = ti->ti_flags; -#if vax + /* + * Drop TCP and IP headers; TCP options were dropped above. + */ + m->m_off += sizeof(struct tcpiphdr); + m->m_len -= sizeof(struct tcpiphdr); + /* * Convert TCP protocol specific fields to host format. */ @@ -103,34 +267,56 @@ printf("tcp_input: bad offset\n"); ti->ti_ack = ntohl(ti->ti_ack); ti->ti_win = ntohs(ti->ti_win); ti->ti_urp = ntohs(ti->ti_urp); -#endif /* * Locate pcb for segment. */ +findpcb: inp = in_pcblookup - (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport); + (&tcb, ti->ti_src, ti->ti_sport, ti->ti_dst, ti->ti_dport, + INPLOOKUP_WILDCARD); /* * If the state is CLOSED (i.e., TCB does not exist) then * all data in the incoming segment is discarded. + * If the TCB exists but is in CLOSED state, it is embryonic, + * but should either do a listen or a connect soon. */ if (inp == 0) goto dropwithreset; tp = intotcpcb(inp); if (tp == 0) goto dropwithreset; -printf("tcp_input: segment seq %x ack %x win %x inp %x flags", -ti->ti_seq, ti->ti_ack, ti->ti_win, inp); -if (ti->ti_flags & TH_FIN) printf(" FIN"); -if (ti->ti_flags & TH_SYN) printf(" SYN"); -if (ti->ti_flags & TH_RST) printf(" RST"); -if (ti->ti_flags & TH_PUSH) printf(" PUSH"); -if (ti->ti_flags & TH_ACK) printf(" ACK"); -if (ti->ti_flags & TH_URG) printf(" URG"); -printf("\n"); -printf("tcp_input: "); pseqno(tp); + if (tp->t_state == TCPS_CLOSED) + goto drop; so = inp->inp_socket; + if (so->so_options & SO_DEBUG) { + ostate = tp->t_state; + tcp_saveti = *ti; + } + if (so->so_options & SO_ACCEPTCONN) { + so = sonewconn(so); + if (so == 0) + goto drop; + /* + * This is ugly, but .... + * + * Mark socket as temporary until we're + * committed to keeping it. The code at + * ``drop'' and ``dropwithreset'' check the + * flag dropsocket to see if the temporary + * socket created here should be discarded. + * We mark the socket as discardable until + * we're committed to it below in TCPS_LISTEN. + */ + dropsocket++; + inp = (struct inpcb *)so->so_pcb; + inp->inp_laddr = ti->ti_dst; + inp->inp_lport = ti->ti_dport; + inp->inp_options = ip_srcroute(); + tp = intotcpcb(inp); + tp->t_state = TCPS_LISTEN; + } /* * Segment received on connection. @@ -139,13 +325,28 @@ printf("tcp_input: "); pseqno(tp); tp->t_idle = 0; tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; + /* + * Process options if not in LISTEN state, + * else do it below (after getting remote address). + */ + if (om && tp->t_state != TCPS_LISTEN) { + tcp_dooptions(tp, om, ti); + om = 0; + } + /* * Calculate amount of space in receive window, * and then do TCP input processing. + * Receive window is amount of space in rcv queue, + * but not less than advertised window. */ - tp->rcv_wnd = sbspace(&so->so_rcv); - if (tp->rcv_wnd < 0) - tp->rcv_wnd = 0; + { int win; + + win = sbspace(&so->so_rcv); + if (win < 0) + win = 0; + tp->rcv_wnd = MAX(win, (int)(tp->rcv_adv - tp->rcv_nxt)); + } switch (tp->t_state) { @@ -153,6 +354,7 @@ printf("tcp_input: "); pseqno(tp); * If the state is LISTEN then ignore segment if it contains an RST. * If the segment contains an ACK then it is bad and send a RST. * If it does not contain a SYN then it is not interesting; drop it. + * Don't bother responding if the destination was a broadcast. * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial * tp->iss, and send a segment: * @@ -161,30 +363,60 @@ printf("tcp_input: "); pseqno(tp); * Enter SYN_RECEIVED state, and process any other fields of this * segment in this state. */ - case TCPS_LISTEN: + case TCPS_LISTEN: { + struct mbuf *am; + register struct sockaddr_in *sin; + if (tiflags & TH_RST) goto drop; if (tiflags & TH_ACK) goto dropwithreset; if ((tiflags & TH_SYN) == 0) goto drop; - tcp_in.sin_addr = ti->ti_src; - tcp_in.sin_port = ti->ti_sport; - if (in_pcbconnect(inp, (struct sockaddr *)&tcp_in)) + if (in_broadcast(ti->ti_dst)) + goto drop; + am = m_get(M_DONTWAIT, MT_SONAME); + if (am == NULL) goto drop; + am->m_len = sizeof (struct sockaddr_in); + sin = mtod(am, struct sockaddr_in *); + sin->sin_family = AF_INET; + sin->sin_addr = ti->ti_src; + sin->sin_port = ti->ti_sport; + laddr = inp->inp_laddr; + if (inp->inp_laddr.s_addr == INADDR_ANY) + inp->inp_laddr = ti->ti_dst; + if (in_pcbconnect(inp, am)) { + inp->inp_laddr = laddr; + (void) m_free(am); + goto drop; + } + (void) m_free(am); tp->t_template = tcp_template(tp); if (tp->t_template == 0) { - in_pcbdisconnect(inp); + tp = tcp_drop(tp, ENOBUFS); + dropsocket = 0; /* socket is already gone */ goto drop; } - tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2; + if (om) { + tcp_dooptions(tp, om, ti); + om = 0; + } + if (iss) + tp->iss = iss; + else + tp->iss = tcp_iss; + tcp_iss += TCP_ISSINCR/2; tp->irs = ti->ti_seq; tcp_sendseqinit(tp); tcp_rcvseqinit(tp); + tp->t_flags |= TF_ACKNOW; tp->t_state = TCPS_SYN_RECEIVED; tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; -printf("tcp_input: out of LISTEN: "); + dropsocket = 0; /* committed to socket */ + tcpstat.tcps_accepts++; goto trimthenstep6; + } /* * If the state is SYN_SENT: @@ -205,25 +437,40 @@ printf("tcp_input: out of LISTEN: "); goto dropwithreset; if (tiflags & TH_RST) { if (tiflags & TH_ACK) - tcp_drop(tp, ECONNRESET); + tp = tcp_drop(tp, ECONNREFUSED); goto drop; } if ((tiflags & TH_SYN) == 0) goto drop; - tp->snd_una = ti->ti_ack; + if (tiflags & TH_ACK) { + tp->snd_una = ti->ti_ack; + if (SEQ_LT(tp->snd_nxt, tp->snd_una)) + tp->snd_nxt = tp->snd_una; + } tp->t_timer[TCPT_REXMT] = 0; tp->irs = ti->ti_seq; tcp_rcvseqinit(tp); tp->t_flags |= TF_ACKNOW; - if (SEQ_GT(tp->snd_una, tp->iss)) { + if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) { + tcpstat.tcps_connects++; soisconnected(so); tp->t_state = TCPS_ESTABLISHED; + tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); (void) tcp_reass(tp, (struct tcpiphdr *)0); - tp->snd_wl1 = ti->ti_seq; + /* + * if we didn't have to retransmit the SYN, + * use its rtt as our initial srtt & rtt var. + */ + if (tp->t_rtt) { + tp->t_srtt = tp->t_rtt << 3; + tp->t_rttvar = tp->t_rtt << 1; + TCPT_RANGESET(tp->t_rxtcur, + ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, + TCPTV_MIN, TCPTV_REXMTMAX); + tp->t_rtt = 0; + } } else tp->t_state = TCPS_SYN_RECEIVED; -printf("tcp_input: out of SYN_SENT: "); - goto trimthenstep6; trimthenstep6: /* @@ -236,77 +483,132 @@ trimthenstep6: todrop = ti->ti_len - tp->rcv_wnd; m_adj(m, -todrop); ti->ti_len = tp->rcv_wnd; - ti->ti_flags &= ~TH_FIN; + tiflags &= ~TH_FIN; + tcpstat.tcps_rcvpackafterwin++; + tcpstat.tcps_rcvbyteafterwin += todrop; } -printf("ti->ti_len %d\n", ti->ti_len); -pseqno(tp); + tp->snd_wl1 = ti->ti_seq - 1; + tp->rcv_up = ti->ti_seq; goto step6; } /* * States other than LISTEN or SYN_SENT. * First check that at least some bytes of segment are within - * receive window. + * receive window. If segment begins before rcv_nxt, + * drop leading data (and SYN); if nothing left, just ack. */ + todrop = tp->rcv_nxt - ti->ti_seq; + if (todrop > 0) { + if (tiflags & TH_SYN) { + tiflags &= ~TH_SYN; + ti->ti_seq++; + if (ti->ti_urp > 1) + ti->ti_urp--; + else + tiflags &= ~TH_URG; + todrop--; + } + if (todrop > ti->ti_len || + todrop == ti->ti_len && (tiflags&TH_FIN) == 0) { +#ifdef TCP_COMPAT_42 + /* + * Don't toss RST in response to 4.2-style keepalive. + */ + if (ti->ti_seq == tp->rcv_nxt - 1 && tiflags & TH_RST) + goto do_rst; +#endif + tcpstat.tcps_rcvduppack++; + tcpstat.tcps_rcvdupbyte += ti->ti_len; + todrop = ti->ti_len; + tiflags &= ~TH_FIN; + tp->t_flags |= TF_ACKNOW; + } else { + tcpstat.tcps_rcvpartduppack++; + tcpstat.tcps_rcvpartdupbyte += todrop; + } + m_adj(m, todrop); + ti->ti_seq += todrop; + ti->ti_len -= todrop; + if (ti->ti_urp > todrop) + ti->ti_urp -= todrop; + else { + tiflags &= ~TH_URG; + ti->ti_urp = 0; + } + } + if (tp->rcv_wnd == 0) { /* * If window is closed can only take segments at * window edge, and have to drop data and PUSH from * incoming segments. + * + * If new data is received on a connection after the + * user processes are gone, then RST the other end. */ - if (tp->rcv_nxt != ti->ti_seq) + if ((so->so_state & SS_NOFDREF) && + tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) { + tp = tcp_close(tp); + tcpstat.tcps_rcvafterclose++; + goto dropwithreset; + } + if (tp->rcv_nxt != ti->ti_seq) { + tcpstat.tcps_rcvpackafterwin++; + tcpstat.tcps_rcvbyteafterwin += ti->ti_len; goto dropafterack; - if (ti->ti_len > 0) { - ti->ti_len = 0; - ti->ti_flags &= ~(TH_PUSH|TH_FIN); } -printf("tcp_input %x: window 0, drop text and FIN\n", tp); - } else { - /* - * If segment begins before rcv_nxt, drop leading - * data (and SYN); if nothing left, just ack. - */ - if (SEQ_GT(tp->rcv_nxt, ti->ti_seq)) { - todrop = tp->rcv_nxt - ti->ti_seq; -printf("tcp_input %x: drop %d dup bytes\n", tp, todrop); - if (tiflags & TH_SYN) { - ti->ti_seq++; - if (ti->ti_urp > 1) - ti->ti_urp--; - else - tiflags &= ~TH_URG; - todrop--; - } - if (todrop > ti->ti_len) - goto dropafterack; - m_adj(m, todrop); - ti->ti_seq += todrop; - ti->ti_len -= todrop; - if (ti->ti_urp > todrop) - ti->ti_urp -= todrop; + if (ti->ti_len > 0) { + if (ti->ti_len == 1) + tcpstat.tcps_rcvwinprobe++; else { - tiflags &= ~TH_URG; - /* ti->ti_flags &= ~TH_URG; */ - /* ti->ti_urp = 0; */ + tcpstat.tcps_rcvpackafterwin++; + tcpstat.tcps_rcvbyteafterwin += ti->ti_len; } - /* tiflags &= ~TH_SYN; */ - /* ti->ti_flags &= ~TH_SYN; */ + m_adj(m, ti->ti_len); + ti->ti_len = 0; + tiflags &= ~(TH_PUSH|TH_FIN); } + } else { /* * If segment ends after window, drop trailing data * (and PUSH and FIN); if nothing left, just ACK. */ - if (SEQ_GT(ti->ti_seq+ti->ti_len, tp->rcv_nxt+tp->rcv_wnd)) { - todrop = - ti->ti_seq+ti->ti_len - (tp->rcv_nxt+tp->rcv_wnd); - if (todrop > ti->ti_len) + todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); + if (todrop > 0) { + if (todrop >= ti->ti_len) { + /* + * If a new connection request is received + * while in TIME_WAIT, drop the old connection + * and start over if the sequence numbers + * are above the previous ones. + */ + if (tiflags & TH_SYN && + tp->t_state == TCPS_TIME_WAIT && + SEQ_GT(ti->ti_seq, tp->rcv_nxt)) { + iss = tp->rcv_nxt + TCP_ISSINCR; + (void) tcp_close(tp); + goto findpcb; + } + if (todrop == 1) + tcpstat.tcps_rcvwinprobe++; + else { + tcpstat.tcps_rcvpackafterwin++; + tcpstat.tcps_rcvbyteafterwin += ti->ti_len; + } goto dropafterack; + } + tcpstat.tcps_rcvpackafterwin++; + tcpstat.tcps_rcvbyteafterwin += todrop; m_adj(m, -todrop); ti->ti_len -= todrop; - ti->ti_flags &= ~(TH_PUSH|TH_FIN); + tiflags &= ~(TH_PUSH|TH_FIN); } } +#ifdef TCP_COMPAT_42 +do_rst: +#endif /* * If the RST bit is set examine the state: * SYN_RECEIVED STATE: @@ -318,30 +620,22 @@ printf("tcp_input %x: drop %d dup bytes\n", tp, todrop); * Close the tcb. */ if (tiflags&TH_RST) switch (tp->t_state) { - + case TCPS_SYN_RECEIVED: - if (inp->inp_socket->so_options & SO_ACCEPTCONN) { - tp->t_state = TCPS_LISTEN; - tp->t_timer[TCPT_KEEP] = 0; - (void) m_free(dtom(tp->t_template)); - tp->t_template = 0; - in_pcbdisconnect(inp); - goto drop; - } - tcp_drop(tp, ECONNREFUSED); + tp = tcp_drop(tp, ECONNREFUSED); goto drop; case TCPS_ESTABLISHED: case TCPS_FIN_WAIT_1: case TCPS_FIN_WAIT_2: case TCPS_CLOSE_WAIT: - tcp_drop(tp, ECONNRESET); + tp = tcp_drop(tp, ECONNRESET); goto drop; case TCPS_CLOSING: case TCPS_LAST_ACK: case TCPS_TIME_WAIT: - tcp_close(tp); + tp = tcp_close(tp); goto drop; } @@ -350,7 +644,7 @@ printf("tcp_input %x: drop %d dup bytes\n", tp, todrop); * error and we send an RST and drop the connection. */ if (tiflags & TH_SYN) { - tcp_drop(tp, ECONNRESET); + tp = tcp_drop(tp, ECONNRESET); goto dropwithreset; } @@ -367,20 +661,19 @@ printf("tcp_input %x: drop %d dup bytes\n", tp, todrop); /* * In SYN_RECEIVED state if the ack ACKs our SYN then enter - * ESTABLISHED state and continue processing, othewise + * ESTABLISHED state and continue processing, otherwise * send an RST. */ case TCPS_SYN_RECEIVED: if (SEQ_GT(tp->snd_una, ti->ti_ack) || SEQ_GT(ti->ti_ack, tp->snd_max)) goto dropwithreset; - tp->snd_una++; /* SYN acked */ - tp->t_timer[TCPT_REXMT] = 0; + tcpstat.tcps_connects++; soisconnected(so); tp->t_state = TCPS_ESTABLISHED; + tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); (void) tcp_reass(tp, (struct tcpiphdr *)0); tp->snd_wl1 = ti->ti_seq - 1; -printf("tcp_input: to ESTAB:\n"); pseqno(tp); /* fall into ... */ /* @@ -398,41 +691,169 @@ printf("tcp_input: to ESTAB:\n"); pseqno(tp); case TCPS_CLOSING: case TCPS_LAST_ACK: case TCPS_TIME_WAIT: -#define ourfinisacked (acked > 0) - if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) + if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) { + if (ti->ti_len == 0 && ti->ti_win == tp->snd_wnd) { + tcpstat.tcps_rcvdupack++; + /* + * If we have outstanding data (not a + * window probe), this is a completely + * duplicate ack (ie, window info didn't + * change), the ack is the biggest we've + * seen and we've seen exactly our rexmt + * threshhold of them, assume a packet + * has been dropped and retransmit it. + * Kludge snd_nxt & the congestion + * window so we send only this one + * packet. If this packet fills the + * only hole in the receiver's seq. + * space, the next real ack will fully + * open our window. This means we + * have to do the usual slow-start to + * not overwhelm an intermediate gateway + * with a burst of packets. Leave + * here with the congestion window set + * to allow 2 packets on the next real + * ack and the exp-to-linear thresh + * set for half the current window + * size (since we know we're losing at + * the current window size). + */ + if (tp->t_timer[TCPT_REXMT] == 0 || + ti->ti_ack != tp->snd_una) + tp->t_dupacks = 0; + else if (++tp->t_dupacks == tcprexmtthresh) { + tcp_seq onxt = tp->snd_nxt; + u_int win = + MIN(tp->snd_wnd, tp->snd_cwnd) / 2 / + tp->t_maxseg; + + if (win < 2) + win = 2; + tp->snd_ssthresh = win * tp->t_maxseg; + + tp->t_timer[TCPT_REXMT] = 0; + tp->t_rtt = 0; + tp->snd_nxt = ti->ti_ack; + tp->snd_cwnd = tp->t_maxseg; + (void) tcp_output(tp); + + if (SEQ_GT(onxt, tp->snd_nxt)) + tp->snd_nxt = onxt; + goto drop; + } + } else + tp->t_dupacks = 0; break; - if (SEQ_GT(ti->ti_ack, tp->snd_max)) + } + tp->t_dupacks = 0; + if (SEQ_GT(ti->ti_ack, tp->snd_max)) { + tcpstat.tcps_rcvacktoomuch++; goto dropafterack; - acked = ti->ti_ack - tp->snd_una; -printf("tcp_input: got ack of %d bytes\n", acked); - if (acked >= so->so_snd.sb_cc) { - acked -= so->so_snd.sb_cc; - /* if acked > 0 our FIN is acked */ - sbdrop(&so->so_snd, so->so_snd.sb_cc); - tp->t_timer[TCPT_REXMT] = 0; - } else { - sbdrop(&so->so_snd, acked); - acked = 0; - TCPT_RANGESET(tp->t_timer[TCPT_REXMT], - tcp_beta * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); } - tp->snd_una = ti->ti_ack; + acked = ti->ti_ack - tp->snd_una; + tcpstat.tcps_rcvackpack++; + tcpstat.tcps_rcvackbyte += acked; /* * If transmit timer is running and timed sequence * number was acked, update smoothed round trip time. + * Since we now have an rtt measurement, cancel the + * timer backoff (cf., Phil Karn's retransmit alg.). + * Recompute the initial retransmit timer. */ if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) { - if (tp->t_srtt == 0) - tp->t_srtt = tp->t_rtt; - else - tp->t_srtt = - tcp_alpha * tp->t_srtt + - (1 - tcp_alpha) * tp->t_rtt; -printf("tcp_input: rtt sampled %d, srtt now %d\n", tp->t_rtt, (int)(100* tp->t_srtt)); + tcpstat.tcps_rttupdated++; + if (tp->t_srtt != 0) { + register short delta; + + /* + * srtt is stored as fixed point with 3 bits + * after the binary point (i.e., scaled by 8). + * The following magic is equivalent + * to the smoothing algorithm in rfc793 + * with an alpha of .875 + * (srtt = rtt/8 + srtt*7/8 in fixed point). + * Adjust t_rtt to origin 0. + */ + tp->t_rtt--; + delta = tp->t_rtt - (tp->t_srtt >> 3); + if ((tp->t_srtt += delta) <= 0) + tp->t_srtt = 1; + /* + * We accumulate a smoothed rtt variance + * (actually, a smoothed mean difference), + * then set the retransmit timer to smoothed + * rtt + 2 times the smoothed variance. + * rttvar is stored as fixed point + * with 2 bits after the binary point + * (scaled by 4). The following is equivalent + * to rfc793 smoothing with an alpha of .75 + * (rttvar = rttvar*3/4 + |delta| / 4). + * This replaces rfc793's wired-in beta. + */ + if (delta < 0) + delta = -delta; + delta -= (tp->t_rttvar >> 2); + if ((tp->t_rttvar += delta) <= 0) + tp->t_rttvar = 1; + } else { + /* + * No rtt measurement yet - use the + * unsmoothed rtt. Set the variance + * to half the rtt (so our first + * retransmit happens at 2*rtt) + */ + tp->t_srtt = tp->t_rtt << 3; + tp->t_rttvar = tp->t_rtt << 1; + } tp->t_rtt = 0; + tp->t_rxtshift = 0; + TCPT_RANGESET(tp->t_rxtcur, + ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, + TCPTV_MIN, TCPTV_REXMTMAX); + } + + /* + * If all outstanding data is acked, stop retransmit + * timer and remember to restart (more output or persist). + * If there is more data to be acked, restart retransmit + * timer, using current (possibly backed-off) value. + */ + if (ti->ti_ack == tp->snd_max) { + tp->t_timer[TCPT_REXMT] = 0; + needoutput = 1; + } else if (tp->t_timer[TCPT_PERSIST] == 0) + tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; + /* + * When new data is acked, open the congestion window. + * If the window gives us less than ssthresh packets + * in flight, open exponentially (maxseg per packet). + * Otherwise open linearly (maxseg per window, + * or maxseg^2 / cwnd per packet). + */ + { + u_int incr = tp->t_maxseg; + + if (tp->snd_cwnd > tp->snd_ssthresh) + incr = MAX(incr * incr / tp->snd_cwnd, 1); + + tp->snd_cwnd = MIN(tp->snd_cwnd + incr, 65535); /* XXX */ } + if (acked > so->so_snd.sb_cc) { + tp->snd_wnd -= so->so_snd.sb_cc; + sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); + ourfinisacked = 1; + } else { + sbdrop(&so->so_snd, acked); + tp->snd_wnd -= acked; + ourfinisacked = 0; + } + if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel) + sowwakeup(so); + tp->snd_una = ti->ti_ack; + if (SEQ_LT(tp->snd_nxt, tp->snd_una)) + tp->snd_nxt = tp->snd_una; switch (tp->t_state) { @@ -442,8 +863,20 @@ printf("tcp_input: rtt sampled %d, srtt now %d\n", tp->t_rtt, (int)(100* tp->t_s * then enter FIN_WAIT_2. */ case TCPS_FIN_WAIT_1: - if (ourfinisacked) + if (ourfinisacked) { + /* + * If we can't receive any more + * data, then closing user can proceed. + * Starting the timer is contrary to the + * specification, but if we don't get a FIN + * we'll hang forever. + */ + if (so->so_state & SS_CANTRCVMORE) { + soisdisconnected(so); + tp->t_timer[TCPT_2MSL] = TCPTV_MAXIDLE; + } tp->t_state = TCPS_FIN_WAIT_2; + } break; /* @@ -462,17 +895,17 @@ printf("tcp_input: rtt sampled %d, srtt now %d\n", tp->t_rtt, (int)(100* tp->t_s break; /* - * The only thing that can arrive in LAST_ACK state - * is an acknowledgment of our FIN. If our FIN is now - * acknowledged, delete the TCB, enter the closed state - * and return. + * In LAST_ACK, we may still be waiting for data to drain + * and/or to be acked, as well as for the ack of our FIN. + * If our FIN is now acknowledged, delete the TCB, + * enter the closed state and return. */ case TCPS_LAST_ACK: if (ourfinisacked) { -printf("tcp_input: LAST ACK close\n"); - tcp_close(tp); + tp = tcp_close(tp); + goto drop; } - goto drop; + break; /* * In TIME_WAIT state the only thing that should arrive @@ -480,44 +913,89 @@ printf("tcp_input: LAST ACK close\n"); * it and restart the finack timer. */ case TCPS_TIME_WAIT: -printf("tcp_input: TIME_WAIT restart timer\n"); tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; goto dropafterack; } -#undef ourfinisacked } step6: /* * Update window information. + * Don't look at window if no ACK: TAC's send garbage on first SYN. */ -printf("update win wl1 %x ti->ti_seq %x wl2 %x?", tp->snd_wl1, ti->ti_seq, tp->snd_wl2); - if (SEQ_LT(tp->snd_wl1, ti->ti_seq) || - tp->snd_wl1==ti->ti_seq && SEQ_LEQ(tp->snd_wl2,ti->ti_seq)) { -printf("yes\n"); + if ((tiflags & TH_ACK) && + (SEQ_LT(tp->snd_wl1, ti->ti_seq) || tp->snd_wl1 == ti->ti_seq && + (SEQ_LT(tp->snd_wl2, ti->ti_ack) || + tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd))) { + /* keep track of pure window updates */ + if (ti->ti_len == 0 && + tp->snd_wl2 == ti->ti_ack && ti->ti_win > tp->snd_wnd) + tcpstat.tcps_rcvwinupd++; tp->snd_wnd = ti->ti_win; tp->snd_wl1 = ti->ti_seq; tp->snd_wl2 = ti->ti_ack; - if (tp->snd_wnd > 0) - tp->t_timer[TCPT_PERSIST] = 0; + if (tp->snd_wnd > tp->max_sndwnd) + tp->max_sndwnd = tp->snd_wnd; + needoutput = 1; } -else printf("no\n"); /* - * If an URG bit is set in the segment and is greater than the - * current known urgent pointer, then signal the user that the - * remote side has out of band data. This should not happen - * in CLOSE_WAIT, CLOSING, LAST-ACK or TIME_WAIT STATES since - * a FIN has been received from the remote side. In these states - * we ignore the URG. + * Process segments with URG. */ - if ((tiflags & TH_URG) == 0 && TCPS_HAVERCVDFIN(tp->t_state) == 0) - if (SEQ_GT(ti->ti_urp, tp->rcv_up)) { - tp->rcv_up = ti->ti_urp; -#if 0 - sohasoutofband(so); /* XXX */ -#endif + if ((tiflags & TH_URG) && ti->ti_urp && + TCPS_HAVERCVDFIN(tp->t_state) == 0) { + /* + * This is a kludge, but if we receive and accept + * random urgent pointers, we'll crash in + * soreceive. It's hard to imagine someone + * actually wanting to send this much urgent data. + */ + if (ti->ti_urp + so->so_rcv.sb_cc > SB_MAX) { + ti->ti_urp = 0; /* XXX */ + tiflags &= ~TH_URG; /* XXX */ + goto dodata; /* XXX */ } + /* + * If this segment advances the known urgent pointer, + * then mark the data stream. This should not happen + * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since + * a FIN has been received from the remote side. + * In these states we ignore the URG. + * + * According to RFC961 (Assigned Protocols), + * the urgent pointer points to the last octet + * of urgent data. We continue, however, + * to consider it to indicate the first octet + * of data past the urgent section + * as the original spec states. + */ + if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { + tp->rcv_up = ti->ti_seq + ti->ti_urp; + so->so_oobmark = so->so_rcv.sb_cc + + (tp->rcv_up - tp->rcv_nxt) - 1; + if (so->so_oobmark == 0) + so->so_state |= SS_RCVATMARK; + sohasoutofband(so); + tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); + } + /* + * Remove out of band data so doesn't get presented to user. + * This can happen independent of advancing the URG pointer, + * but if two URG's are pending at once, some out-of-band + * data may creep in... ick. + */ + if (ti->ti_urp <= ti->ti_len && + (so->so_options & SO_OOBINLINE) == 0) + tcp_pulloutofband(so, ti); + } else + /* + * If no out of band data is expected, + * pull receive urgent pointer along + * with the receive window. + */ + if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) + tp->rcv_up = tp->rcv_nxt; +dodata: /* XXX */ /* * Process the segment text, merging it into the TCP sequencing queue, @@ -527,30 +1005,36 @@ else printf("no\n"); * case PRU_RCVD). If a FIN has already been received on this * connection then we just ignore the text. */ - if (ti->ti_len && TCPS_HAVERCVDFIN(tp->t_state) == 0) { - off += sizeof (struct ip); /* drop IP header */ - m->m_off += off; - m->m_len -= off; - tiflags = tcp_reass(tp, ti); - tp->t_flags |= TF_ACKNOW; /* XXX TF_DELACK */ + if ((ti->ti_len || (tiflags&TH_FIN)) && + TCPS_HAVERCVDFIN(tp->t_state) == 0) { + TCP_REASS(tp, ti, m, so, tiflags); + if (tcpnodelack == 0) + tp->t_flags |= TF_DELACK; + else + tp->t_flags |= TF_ACKNOW; + /* + * Note the amount of data that peer has sent into + * our window, in order to estimate the sender's + * buffer size. + */ + len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); + if (len > tp->max_rcvd) + tp->max_rcvd = len; } else { m_freem(m); + tiflags &= ~TH_FIN; } /* - * If FIN is received then if we haven't received SYN and - * therefore can't validate drop the segment. Otherwise ACK - * the FIN and let the user know that the connection is closing. + * If FIN is received ACK the FIN and let the user know + * that the connection is closing. */ - if ((tiflags & TH_FIN)) { - if (TCPS_HAVERCVDSYN(tp->t_state) == 0) - goto drop; + if (tiflags & TH_FIN) { if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { socantrcvmore(so); tp->t_flags |= TF_ACKNOW; tp->rcv_nxt++; } -printf("tcp_input: %x got FIN\n", tp); switch (tp->t_state) { /* @@ -590,143 +1074,192 @@ printf("tcp_input: %x got FIN\n", tp); break; } } + if (so->so_options & SO_DEBUG) + tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); /* * Return any desired output. */ - tcp_output(tp); + if (needoutput || (tp->t_flags & TF_ACKNOW)) + (void) tcp_output(tp); return; dropafterack: /* - * Generate an ACK dropping incoming segment. - * Make ACK reflect our state. + * Generate an ACK dropping incoming segment if it occupies + * sequence space, where the ACK reflects our state. */ -printf("tcp_input: dropafterack\n"); if (tiflags & TH_RST) goto drop; - tcp_respond(ti, tp->rcv_nxt, tp->snd_nxt, TH_ACK); + m_freem(m); + tp->t_flags |= TF_ACKNOW; + (void) tcp_output(tp); return; dropwithreset: -printf("tcp_input: dropwithreset\n"); + if (om) { + (void) m_free(om); + om = 0; + } /* * Generate a RST, dropping incoming segment. * Make ACK acceptable to originator of segment. + * Don't bother to respond if destination was broadcast. */ - if (tiflags & TH_RST) + if ((tiflags & TH_RST) || in_broadcast(ti->ti_dst)) goto drop; if (tiflags & TH_ACK) - tcp_respond(ti, (tcp_seq)0, ti->ti_ack, TH_RST); + tcp_respond(tp, ti, (tcp_seq)0, ti->ti_ack, TH_RST); else { if (tiflags & TH_SYN) ti->ti_len++; - tcp_respond(ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, TH_RST|TH_ACK); + tcp_respond(tp, ti, ti->ti_seq+ti->ti_len, (tcp_seq)0, + TH_RST|TH_ACK); } + /* destroy temporarily created socket */ + if (dropsocket) + (void) soabort(so); return; drop: -printf("tcp_input: drop\n"); + if (om) + (void) m_free(om); /* * Drop space held by incoming segment and return. */ + if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) + tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); m_freem(m); + /* destroy temporarily created socket */ + if (dropsocket) + (void) soabort(so); + return; } -/* - * Insert segment ti into reassembly queue of tcp with - * control block tp. Return TH_FIN if reassembly now includes - * a segment with FIN. - */ -tcp_reass(tp, ti) - register struct tcpcb *tp; - register struct tcpiphdr *ti; +tcp_dooptions(tp, om, ti) + struct tcpcb *tp; + struct mbuf *om; + struct tcpiphdr *ti; { - register struct tcpiphdr *q; - struct socket *so = tp->t_inpcb->inp_socket; - int flags = 0; /* no FIN */ -COUNT(TCP_REASS); + register u_char *cp; + int opt, optlen, cnt; - /* - * Call with ti==0 after become established to - * force pre-ESTABLISHED data up to user socket. - */ - if (ti == 0) - goto present; + cp = mtod(om, u_char *); + cnt = om->m_len; + for (; cnt > 0; cnt -= optlen, cp += optlen) { + opt = cp[0]; + if (opt == TCPOPT_EOL) + break; + if (opt == TCPOPT_NOP) + optlen = 1; + else { + optlen = cp[1]; + if (optlen <= 0) + break; + } + switch (opt) { - /* - * Find a segment which begins after this one does. - */ - for (q = tp->seg_next; q != (struct tcpiphdr *)tp; - q = (struct tcpiphdr *)q->ti_next) - if (SEQ_GT(q->ti_seq, ti->ti_seq)) + default: break; - /* - * 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. - */ - if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { - register int i; - q = (struct tcpiphdr *)(q->ti_prev); - /* conversion to int (in i) handles seq wraparound */ - i = q->ti_seq + q->ti_len - ti->ti_seq; - if (i > 0) { - if (i >= ti->ti_len) - goto drop; - m_adj(dtom(tp), i); - ti->ti_len -= i; - ti->ti_seq += i; + case TCPOPT_MAXSEG: + if (optlen != 4) + continue; + if (!(ti->ti_flags & TH_SYN)) + continue; + tp->t_maxseg = *(u_short *)(cp + 2); + tp->t_maxseg = ntohs((u_short)tp->t_maxseg); + tp->t_maxseg = MIN(tp->t_maxseg, tcp_mss(tp)); + break; } - q = (struct tcpiphdr *)(q->ti_next); } + (void) m_free(om); +} - /* - * While we overlap succeeding segments trim them or, - * if they are completely covered, dequeue them. - */ - while (q != (struct tcpiphdr *)tp && - SEQ_GT(ti->ti_seq + ti->ti_len, q->ti_seq)) { - register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; - if (i < q->ti_len) { - q->ti_len -= i; - m_adj(dtom(q), i); - break; +/* + * Pull out of band byte out of a segment so + * it doesn't appear in the user's data queue. + * It is still reflected in the segment length for + * sequencing purposes. + */ +tcp_pulloutofband(so, ti) + struct socket *so; + struct tcpiphdr *ti; +{ + register struct mbuf *m; + int cnt = ti->ti_urp - 1; + + m = dtom(ti); + while (cnt >= 0) { + if (m->m_len > cnt) { + char *cp = mtod(m, caddr_t) + cnt; + struct tcpcb *tp = sototcpcb(so); + + tp->t_iobc = *cp; + tp->t_oobflags |= TCPOOB_HAVEDATA; + bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); + m->m_len--; + return; } - q = (struct tcpiphdr *)q->ti_next; - m_freem(dtom(q->ti_prev)); - remque(q->ti_prev); + cnt -= m->m_len; + m = m->m_next; + if (m == 0) + break; } + panic("tcp_pulloutofband"); +} - /* - * Stick new segment in its place. - */ - insque(ti, q->ti_prev); +/* + * Determine a reasonable value for maxseg size. + * If the route is known, use one that can be handled + * on the given interface without forcing IP to fragment. + * If bigger than an mbuf cluster (MCLBYTES), round down to nearest size + * to utilize large mbufs. + * If interface pointer is unavailable, or the destination isn't local, + * use a conservative size (512 or the default IP max size, but no more + * than the mtu of the interface through which we route), + * as we can't discover anything about intervening gateways or networks. + * We also initialize the congestion/slow start window to be a single + * segment if the destination isn't local; this information should + * probably all be saved with the routing entry at the transport level. + * + * This is ugly, and doesn't belong at this level, but has to happen somehow. + */ +tcp_mss(tp) + register struct tcpcb *tp; +{ + struct route *ro; + struct ifnet *ifp; + int mss; + struct inpcb *inp; -present: - /* - * Present data to user, advancing rcv_nxt through - * completed sequence space. - */ - if (tp->t_state < TCPS_ESTABLISHED) - return (0); - ti = tp->seg_next; - while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt) { - tp->rcv_nxt += ti->ti_len; - flags = ti->ti_flags & TH_FIN; -printf("move %d bytes to user; rcv_nxt now %x\n", ti->ti_len, tp->rcv_nxt); - remque(ti); - sbappend(&so->so_rcv, dtom(ti)); - ti = (struct tcpiphdr *)ti->ti_next; + inp = tp->t_inpcb; + ro = &inp->inp_route; + if ((ro->ro_rt == (struct rtentry *)0) || + (ifp = ro->ro_rt->rt_ifp) == (struct ifnet *)0) { + /* No route yet, so try to acquire one */ + if (inp->inp_faddr.s_addr != INADDR_ANY) { + ro->ro_dst.sa_family = AF_INET; + ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = + inp->inp_faddr; + rtalloc(ro); + } + if ((ro->ro_rt == 0) || (ifp = ro->ro_rt->rt_ifp) == 0) + return (TCP_MSS); } - if (so->so_state & SS_CANTRCVMORE) - sbflush(&so->so_rcv); - else - sorwakeup(so); - return (flags); -drop: -printf("tcp_reass drop\n"); - m_freem(dtom(ti)); - return (flags); + + mss = ifp->if_mtu - sizeof(struct tcpiphdr); +#if (MCLBYTES & (MCLBYTES - 1)) == 0 + if (mss > MCLBYTES) + mss &= ~(MCLBYTES-1); +#else + if (mss > MCLBYTES) + mss = mss / MCLBYTES * MCLBYTES; +#endif + if (in_localaddr(inp->inp_faddr)) + return (mss); + + mss = MIN(mss, TCP_MSS); + tp->snd_cwnd = mss; + return (mss); }