diff options
Diffstat (limited to 'sys/netinet')
| -rw-r--r-- | sys/netinet/tcp_reass.c | 1647 | ||||
| -rw-r--r-- | sys/netinet/tcp_timewait.c | 445 |
2 files changed, 2092 insertions, 0 deletions
diff --git a/sys/netinet/tcp_reass.c b/sys/netinet/tcp_reass.c new file mode 100644 index 0000000..2dd1d74 --- /dev/null +++ b/sys/netinet/tcp_reass.c @@ -0,0 +1,1647 @@ +/* + * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * @(#)tcp_input.c 8.5 (Berkeley) 4/10/94 + */ + +#ifndef TUBA_INCLUDE +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/protosw.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/errno.h> + +#include <net/if.h> +#include <net/route.h> + +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/in_pcb.h> +#include <netinet/ip_var.h> +#include <netinet/tcp.h> +#include <netinet/tcp_fsm.h> +#include <netinet/tcp_seq.h> +#include <netinet/tcp_timer.h> +#include <netinet/tcp_var.h> +#include <netinet/tcpip.h> +#include <netinet/tcp_debug.h> + +int tcprexmtthresh = 3; +struct tcpiphdr tcp_saveti; +struct inpcb *tcp_last_inpcb = &tcb; + +extern u_long sb_max; + +#endif /* TUBA_INCLUDE */ +#define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ) + +/* for modulo comparisons of timestamps */ +#define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) +#define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) + + +/* + * 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. + * Set DELACK for segments received in order, but ack immediately + * when segments are out of order (so fast retransmit can work). + */ +#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->t_flags |= TF_DELACK; \ + (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), (m)); \ + tp->t_flags |= TF_ACKNOW; \ + } \ +} +#ifndef TUBA_INCLUDE + +int +tcp_reass(tp, ti, m) + register struct tcpcb *tp; + register struct tcpiphdr *ti; + struct mbuf *m; +{ + register struct tcpiphdr *q; + struct socket *so = tp->t_inpcb->inp_socket; + 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; + m_freem(m); + return (0); + } + m_adj(m, i); + ti->ti_len -= i; + ti->ti_seq += i; + } + q = (struct tcpiphdr *)(q->ti_next); + } + tcpstat.tcps_rcvoopack++; + tcpstat.tcps_rcvoobyte += ti->ti_len; + REASS_MBUF(ti) = m; /* XXX */ + + /* + * 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(REASS_MBUF(q), i); + break; + } + q = (struct tcpiphdr *)q->ti_next; + m = REASS_MBUF((struct tcpiphdr *)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 = REASS_MBUF(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); +} + +/* + * TCP input routine, follows pages 65-76 of the + * protocol specification dated September, 1981 very closely. + */ +void +tcp_input(m, iphlen) + register struct mbuf *m; + int iphlen; +{ + register struct tcpiphdr *ti; + register struct inpcb *inp; + caddr_t optp = NULL; + int optlen; + int len, tlen, off; + register struct tcpcb *tp = 0; + register int tiflags; + struct socket *so; + int todrop, acked, ourfinisacked, needoutput = 0; + short ostate; + struct in_addr laddr; + int dropsocket = 0; + int iss = 0; + u_long tiwin, ts_val, ts_ecr; + int ts_present = 0; + + tcpstat.tcps_rcvtotal++; + /* + * Get IP and TCP header together in first mbuf. + * Note: IP leaves IP header in first mbuf. + */ + ti = mtod(m, struct tcpiphdr *); + if (iphlen > sizeof (struct ip)) + ip_stripoptions(m, (struct mbuf *)0); + if (m->m_len < sizeof (struct tcpiphdr)) { + if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { + tcpstat.tcps_rcvshort++; + return; + } + ti = mtod(m, struct tcpiphdr *); + } + + /* + * Checksum extended TCP header and data. + */ + tlen = ((struct ip *)ti)->ip_len; + len = sizeof (struct ip) + tlen; + ti->ti_next = ti->ti_prev = 0; + ti->ti_x1 = 0; + ti->ti_len = (u_short)tlen; + HTONS(ti->ti_len); + if (ti->ti_sum = in_cksum(m, len)) { + tcpstat.tcps_rcvbadsum++; + goto drop; + } +#endif /* TUBA_INCLUDE */ + + /* + * Check that TCP offset makes sense, + * pull out TCP options and adjust length. XXX + */ + off = ti->ti_off << 2; + if (off < sizeof (struct tcphdr) || off > tlen) { + tcpstat.tcps_rcvbadoff++; + goto drop; + } + 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 *); + } + optlen = off - sizeof (struct tcphdr); + optp = mtod(m, caddr_t) + sizeof (struct tcpiphdr); + /* + * Do quick retrieval of timestamp options ("options + * prediction?"). If timestamp is the only option and it's + * formatted as recommended in RFC 1323 appendix A, we + * quickly get the values now and not bother calling + * tcp_dooptions(), etc. + */ + if ((optlen == TCPOLEN_TSTAMP_APPA || + (optlen > TCPOLEN_TSTAMP_APPA && + optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && + *(u_long *)optp == htonl(TCPOPT_TSTAMP_HDR) && + (ti->ti_flags & TH_SYN) == 0) { + ts_present = 1; + ts_val = ntohl(*(u_long *)(optp + 4)); + ts_ecr = ntohl(*(u_long *)(optp + 8)); + optp = NULL; /* we've parsed the options */ + } + } + tiflags = ti->ti_flags; + + /* + * Convert TCP protocol specific fields to host format. + */ + NTOHL(ti->ti_seq); + NTOHL(ti->ti_ack); + NTOHS(ti->ti_win); + NTOHS(ti->ti_urp); + + /* + * Locate pcb for segment. + */ +findpcb: + inp = tcp_last_inpcb; + if (inp->inp_lport != ti->ti_dport || + inp->inp_fport != ti->ti_sport || + inp->inp_faddr.s_addr != ti->ti_src.s_addr || + inp->inp_laddr.s_addr != ti->ti_dst.s_addr) { + inp = in_pcblookup(&tcb, ti->ti_src, ti->ti_sport, + ti->ti_dst, ti->ti_dport, INPLOOKUP_WILDCARD); + if (inp) + tcp_last_inpcb = inp; + ++tcpstat.tcps_pcbcachemiss; + } + + /* + * 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; + if (tp->t_state == TCPS_CLOSED) + goto drop; + + /* Unscale the window into a 32-bit value. */ + if ((tiflags & TH_SYN) == 0) + tiwin = ti->ti_win << tp->snd_scale; + else + tiwin = ti->ti_win; + + so = inp->inp_socket; + if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { + if (so->so_options & SO_DEBUG) { + ostate = tp->t_state; + tcp_saveti = *ti; + } + if (so->so_options & SO_ACCEPTCONN) { + so = sonewconn(so, 0); + 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; +#if BSD>=43 + inp->inp_options = ip_srcroute(); +#endif + tp = intotcpcb(inp); + tp->t_state = TCPS_LISTEN; + + /* Compute proper scaling value from buffer space + */ + while (tp->request_r_scale < TCP_MAX_WINSHIFT && + TCP_MAXWIN << tp->request_r_scale < so->so_rcv.sb_hiwat) + tp->request_r_scale++; + } + } + + /* + * Segment received on connection. + * Reset idle time and keep-alive timer. + */ + tp->t_idle = 0; + tp->t_timer[TCPT_KEEP] = tcp_keepidle; + + /* + * Process options if not in LISTEN state, + * else do it below (after getting remote address). + */ + if (optp && tp->t_state != TCPS_LISTEN) + tcp_dooptions(tp, optp, optlen, ti, + &ts_present, &ts_val, &ts_ecr); + + /* + * Header prediction: check for the two common cases + * of a uni-directional data xfer. If the packet has + * no control flags, is in-sequence, the window didn't + * change and we're not retransmitting, it's a + * candidate. If the length is zero and the ack moved + * forward, we're the sender side of the xfer. Just + * free the data acked & wake any higher level process + * that was blocked waiting for space. If the length + * is non-zero and the ack didn't move, we're the + * receiver side. If we're getting packets in-order + * (the reassembly queue is empty), add the data to + * the socket buffer and note that we need a delayed ack. + */ + if (tp->t_state == TCPS_ESTABLISHED && + (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && + (!ts_present || TSTMP_GEQ(ts_val, tp->ts_recent)) && + ti->ti_seq == tp->rcv_nxt && + tiwin && tiwin == tp->snd_wnd && + tp->snd_nxt == tp->snd_max) { + + /* + * If last ACK falls within this segment's sequence numbers, + * record the timestamp. + */ + if (ts_present && SEQ_LEQ(ti->ti_seq, tp->last_ack_sent) && + SEQ_LT(tp->last_ack_sent, ti->ti_seq + ti->ti_len)) { + tp->ts_recent_age = tcp_now; + tp->ts_recent = ts_val; + } + + if (ti->ti_len == 0) { + if (SEQ_GT(ti->ti_ack, tp->snd_una) && + SEQ_LEQ(ti->ti_ack, tp->snd_max) && + tp->snd_cwnd >= tp->snd_wnd) { + /* + * this is a pure ack for outstanding data. + */ + ++tcpstat.tcps_predack; + if (ts_present) + tcp_xmit_timer(tp, tcp_now-ts_ecr+1); + else if (tp->t_rtt && + SEQ_GT(ti->ti_ack, tp->t_rtseq)) + tcp_xmit_timer(tp, tp->t_rtt); + acked = ti->ti_ack - tp->snd_una; + tcpstat.tcps_rcvackpack++; + tcpstat.tcps_rcvackbyte += acked; + sbdrop(&so->so_snd, acked); + tp->snd_una = ti->ti_ack; + m_freem(m); + + /* + * If all outstanding data are acked, stop + * retransmit timer, otherwise restart timer + * using current (possibly backed-off) value. + * If process is waiting for space, + * wakeup/selwakeup/signal. If data + * are ready to send, let tcp_output + * decide between more output or persist. + */ + if (tp->snd_una == tp->snd_max) + tp->t_timer[TCPT_REXMT] = 0; + else if (tp->t_timer[TCPT_PERSIST] == 0) + tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; + + if (so->so_snd.sb_flags & SB_NOTIFY) + sowwakeup(so); + if (so->so_snd.sb_cc) + (void) tcp_output(tp); + return; + } + } else if (ti->ti_ack == tp->snd_una && + tp->seg_next == (struct tcpiphdr *)tp && + ti->ti_len <= sbspace(&so->so_rcv)) { + /* + * this is a pure, in-sequence data packet + * with nothing on the reassembly queue and + * we have enough buffer space to take it. + */ + ++tcpstat.tcps_preddat; + tp->rcv_nxt += ti->ti_len; + tcpstat.tcps_rcvpack++; + tcpstat.tcps_rcvbyte += ti->ti_len; + /* + * Drop TCP, IP headers and TCP options then add data + * to socket buffer. + */ + m->m_data += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); + m->m_len -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); + sbappend(&so->so_rcv, m); + sorwakeup(so); + tp->t_flags |= TF_DELACK; + return; + } + } + + /* + * Drop TCP, IP headers and TCP options. + */ + m->m_data += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); + m->m_len -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); + + /* + * 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. + */ + { 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) { + + /* + * 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: + * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> + * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. + * Fill in remote peer address fields if not previously specified. + * Enter SYN_RECEIVED state, and process any other fields of this + * segment in this state. + */ + 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; + /* + * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN + * in_broadcast() should never return true on a received + * packet with M_BCAST not set. + */ + if (m->m_flags & (M_BCAST|M_MCAST) || + IN_MULTICAST(ti->ti_dst.s_addr)) + goto drop; + am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ + 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_len = sizeof(*sin); + sin->sin_addr = ti->ti_src; + sin->sin_port = ti->ti_sport; + bzero((caddr_t)sin->sin_zero, sizeof(sin->sin_zero)); + 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) { + tp = tcp_drop(tp, ENOBUFS); + dropsocket = 0; /* socket is already gone */ + goto drop; + } + if (optp) + tcp_dooptions(tp, optp, optlen, ti, + &ts_present, &ts_val, &ts_ecr); + 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_INIT; + dropsocket = 0; /* committed to socket */ + tcpstat.tcps_accepts++; + goto trimthenstep6; + } + + /* + * If the state is SYN_SENT: + * if seg contains an ACK, but not for our SYN, drop the input. + * if seg contains a RST, then drop the connection. + * if seg does not contain SYN, then drop it. + * Otherwise this is an acceptable SYN segment + * initialize tp->rcv_nxt and tp->irs + * if seg contains ack then advance tp->snd_una + * if SYN has been acked change to ESTABLISHED else SYN_RCVD state + * arrange for segment to be acked (eventually) + * continue processing rest of data/controls, beginning with URG + */ + case TCPS_SYN_SENT: + if ((tiflags & TH_ACK) && + (SEQ_LEQ(ti->ti_ack, tp->iss) || + SEQ_GT(ti->ti_ack, tp->snd_max))) + goto dropwithreset; + if (tiflags & TH_RST) { + if (tiflags & TH_ACK) + tp = tcp_drop(tp, ECONNREFUSED); + goto drop; + } + if ((tiflags & TH_SYN) == 0) + goto drop; + 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 (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) { + tcpstat.tcps_connects++; + soisconnected(so); + tp->t_state = TCPS_ESTABLISHED; + /* Do window scaling on this connection? */ + if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == + (TF_RCVD_SCALE|TF_REQ_SCALE)) { + tp->snd_scale = tp->requested_s_scale; + tp->rcv_scale = tp->request_r_scale; + } + (void) tcp_reass(tp, (struct tcpiphdr *)0, + (struct mbuf *)0); + /* + * if we didn't have to retransmit the SYN, + * use its rtt as our initial srtt & rtt var. + */ + if (tp->t_rtt) + tcp_xmit_timer(tp, tp->t_rtt); + } else + tp->t_state = TCPS_SYN_RECEIVED; + +trimthenstep6: + /* + * Advance ti->ti_seq to correspond to first data byte. + * If data, trim to stay within window, + * dropping FIN if necessary. + */ + ti->ti_seq++; + if (ti->ti_len > tp->rcv_wnd) { + todrop = ti->ti_len - tp->rcv_wnd; + m_adj(m, -todrop); + ti->ti_len = tp->rcv_wnd; + tiflags &= ~TH_FIN; + tcpstat.tcps_rcvpackafterwin++; + tcpstat.tcps_rcvbyteafterwin += todrop; + } + tp->snd_wl1 = ti->ti_seq - 1; + tp->rcv_up = ti->ti_seq; + goto step6; + } + + /* + * States other than LISTEN or SYN_SENT. + * First check timestamp, if present. + * Then check that at least some bytes of segment are within + * receive window. If segment begins before rcv_nxt, + * drop leading data (and SYN); if nothing left, just ack. + * + * RFC 1323 PAWS: If we have a timestamp reply on this segment + * and it's less than ts_recent, drop it. + */ + if (ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && + TSTMP_LT(ts_val, tp->ts_recent)) { + + /* Check to see if ts_recent is over 24 days old. */ + if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) { + /* + * Invalidate ts_recent. If this segment updates + * ts_recent, the age will be reset later and ts_recent + * will get a valid value. If it does not, setting + * ts_recent to zero will at least satisfy the + * requirement that zero be placed in the timestamp + * echo reply when ts_recent isn't valid. The + * age isn't reset until we get a valid ts_recent + * because we don't want out-of-order segments to be + * dropped when ts_recent is old. + */ + tp->ts_recent = 0; + } else { + tcpstat.tcps_rcvduppack++; + tcpstat.tcps_rcvdupbyte += ti->ti_len; + tcpstat.tcps_pawsdrop++; + goto dropafterack; + } + } + + 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) { + tcpstat.tcps_rcvduppack++; + tcpstat.tcps_rcvdupbyte += ti->ti_len; + /* + * If segment is just one to the left of the window, + * check two special cases: + * 1. Don't toss RST in response to 4.2-style keepalive. + * 2. If the only thing to drop is a FIN, we can drop + * it, but check the ACK or we will get into FIN + * wars if our FINs crossed (both CLOSING). + * In either case, send ACK to resynchronize, + * but keep on processing for RST or ACK. + */ + if ((tiflags & TH_FIN && todrop == ti->ti_len + 1) +#ifdef TCP_COMPAT_42 + || (tiflags & TH_RST && ti->ti_seq == tp->rcv_nxt - 1) +#endif + ) { + todrop = ti->ti_len; + tiflags &= ~TH_FIN; + tp->t_flags |= TF_ACKNOW; + } else { + /* + * Handle the case when a bound socket connects + * to itself. Allow packets with a SYN and + * an ACK to continue with the processing. + */ + if (todrop != 0 || (tiflags & TH_ACK) == 0) + goto dropafterack; + } + } 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 new data are received on a connection after the + * user processes are gone, then RST the other end. + */ + 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 segment ends after window, drop trailing data + * (and PUSH and FIN); if nothing left, just ACK. + */ + todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); + if (todrop > 0) { + tcpstat.tcps_rcvpackafterwin++; + if (todrop >= ti->ti_len) { + tcpstat.tcps_rcvbyteafterwin += 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; + tp = tcp_close(tp); + goto findpcb; + } + /* + * If window is closed can only take segments at + * window edge, and have to drop data and PUSH from + * incoming segments. Continue processing, but + * remember to ack. Otherwise, drop segment + * and ack. + */ + if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) { + tp->t_flags |= TF_ACKNOW; + tcpstat.tcps_rcvwinprobe++; + } else + goto dropafterack; + } else + tcpstat.tcps_rcvbyteafterwin += todrop; + m_adj(m, -todrop); + ti->ti_len -= todrop; + tiflags &= ~(TH_PUSH|TH_FIN); + } + + /* + * If last ACK falls within this segment's sequence numbers, + * record its timestamp. + */ + if (ts_present && SEQ_LEQ(ti->ti_seq, tp->last_ack_sent) && + SEQ_LT(tp->last_ack_sent, ti->ti_seq + ti->ti_len + + ((tiflags & (TH_SYN|TH_FIN)) != 0))) { + tp->ts_recent_age = tcp_now; + tp->ts_recent = ts_val; + } + + /* + * If the RST bit is set examine the state: + * SYN_RECEIVED STATE: + * If passive open, return to LISTEN state. + * If active open, inform user that connection was refused. + * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: + * Inform user that connection was reset, and close tcb. + * CLOSING, LAST_ACK, TIME_WAIT STATES + * Close the tcb. + */ + if (tiflags&TH_RST) switch (tp->t_state) { + + case TCPS_SYN_RECEIVED: + so->so_error = ECONNREFUSED; + goto close; + + case TCPS_ESTABLISHED: + case TCPS_FIN_WAIT_1: + case TCPS_FIN_WAIT_2: + case TCPS_CLOSE_WAIT: + so->so_error = ECONNRESET; + close: + tp->t_state = TCPS_CLOSED; + tcpstat.tcps_drops++; + tp = tcp_close(tp); + goto drop; + + case TCPS_CLOSING: + case TCPS_LAST_ACK: + case TCPS_TIME_WAIT: + tp = tcp_close(tp); + goto drop; + } + + /* + * If a SYN is in the window, then this is an + * error and we send an RST and drop the connection. + */ + if (tiflags & TH_SYN) { + tp = tcp_drop(tp, ECONNRESET); + goto dropwithreset; + } + + /* + * If the ACK bit is off we drop the segment and return. + */ + if ((tiflags & TH_ACK) == 0) + goto drop; + + /* + * Ack processing. + */ + switch (tp->t_state) { + + /* + * In SYN_RECEIVED state if the ack ACKs our SYN then enter + * 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; + tcpstat.tcps_connects++; + soisconnected(so); + tp->t_state = TCPS_ESTABLISHED; + /* Do window scaling? */ + if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == + (TF_RCVD_SCALE|TF_REQ_SCALE)) { + tp->snd_scale = tp->requested_s_scale; + tp->rcv_scale = tp->request_r_scale; + } + (void) tcp_reass(tp, (struct tcpiphdr *)0, (struct mbuf *)0); + tp->snd_wl1 = ti->ti_seq - 1; + /* fall into ... */ + + /* + * In ESTABLISHED state: drop duplicate ACKs; ACK out of range + * ACKs. If the ack is in the range + * tp->snd_una < ti->ti_ack <= tp->snd_max + * then advance tp->snd_una to ti->ti_ack and drop + * data from the retransmission queue. If this ACK reflects + * more up to date window information we update our window information. + */ + case TCPS_ESTABLISHED: + case TCPS_FIN_WAIT_1: + case TCPS_FIN_WAIT_2: + case TCPS_CLOSE_WAIT: + case TCPS_CLOSING: + case TCPS_LAST_ACK: + case TCPS_TIME_WAIT: + + if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) { + if (ti->ti_len == 0 && tiwin == tp->snd_wnd) { + tcpstat.tcps_rcvdupack++; + /* + * If we have outstanding data (other than + * 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. + * + * We know we're losing at the current + * window size so do congestion avoidance + * (set ssthresh to half the current window + * and pull our congestion window back to + * the new ssthresh). + * + * Dup acks mean that packets have left the + * network (they're now cached at the receiver) + * so bump cwnd by the amount in the receiver + * to keep a constant cwnd packets in the + * network. + */ + 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); + tp->snd_cwnd = tp->snd_ssthresh + + tp->t_maxseg * tp->t_dupacks; + if (SEQ_GT(onxt, tp->snd_nxt)) + tp->snd_nxt = onxt; + goto drop; + } else if (tp->t_dupacks > tcprexmtthresh) { + tp->snd_cwnd += tp->t_maxseg; + (void) tcp_output(tp); + goto drop; + } + } else + tp->t_dupacks = 0; + break; + } + /* + * If the congestion window was inflated to account + * for the other side's cached packets, retract it. + */ + if (tp->t_dupacks > tcprexmtthresh && + tp->snd_cwnd > tp->snd_ssthresh) + tp->snd_cwnd = tp->snd_ssthresh; + 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; + tcpstat.tcps_rcvackpack++; + tcpstat.tcps_rcvackbyte += acked; + + /* + * If we have a timestamp reply, update smoothed + * round trip time. If no timestamp is present but + * 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 (ts_present) + tcp_xmit_timer(tp, tcp_now-ts_ecr+1); + else if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) + tcp_xmit_timer(tp,tp->t_rtt); + + /* + * 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 + * (maxseg^2 / cwnd per packet), plus a constant + * fraction of a packet (maxseg/8) to help larger windows + * open quickly enough. + */ + { + register u_int cw = tp->snd_cwnd; + register u_int incr = tp->t_maxseg; + + if (cw > tp->snd_ssthresh) + incr = incr * incr / cw + incr / 8; + tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale); + } + 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_NOTIFY) + 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) { + + /* + * In FIN_WAIT_1 STATE in addition to the processing + * for the ESTABLISHED state if our FIN is now acknowledged + * then enter FIN_WAIT_2. + */ + case TCPS_FIN_WAIT_1: + 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] = tcp_maxidle; + } + tp->t_state = TCPS_FIN_WAIT_2; + } + break; + + /* + * In CLOSING STATE in addition to the processing for + * the ESTABLISHED state if the ACK acknowledges our FIN + * then enter the TIME-WAIT state, otherwise ignore + * the segment. + */ + case TCPS_CLOSING: + if (ourfinisacked) { + tp->t_state = TCPS_TIME_WAIT; + tcp_canceltimers(tp); + tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; + soisdisconnected(so); + } + break; + + /* + * 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) { + tp = tcp_close(tp); + goto drop; + } + break; + + /* + * In TIME_WAIT state the only thing that should arrive + * is a retransmission of the remote FIN. Acknowledge + * it and restart the finack timer. + */ + case TCPS_TIME_WAIT: + tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; + goto dropafterack; + } + } + +step6: + /* + * Update window information. + * Don't look at window if no ACK: TAC's send garbage on first SYN. + */ + 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 && tiwin > tp->snd_wnd))) { + /* keep track of pure window updates */ + if (ti->ti_len == 0 && + tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd) + tcpstat.tcps_rcvwinupd++; + tp->snd_wnd = tiwin; + tp->snd_wl1 = ti->ti_seq; + tp->snd_wl2 = ti->ti_ack; + if (tp->snd_wnd > tp->max_sndwnd) + tp->max_sndwnd = tp->snd_wnd; + needoutput = 1; + } + + /* + * Process segments with URG. + */ + 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 (in one of two places). + */ + 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 +#ifdef SO_OOBINLINE + && (so->so_options & SO_OOBINLINE) == 0 +#endif + ) + tcp_pulloutofband(so, ti, m); + } 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, + * and arranging for acknowledgment of receipt if necessary. + * This process logically involves adjusting tp->rcv_wnd as data + * is presented to the user (this happens in tcp_usrreq.c, + * case PRU_RCVD). If a FIN has already been received on this + * connection then we just ignore the text. + */ + if ((ti->ti_len || (tiflags&TH_FIN)) && + TCPS_HAVERCVDFIN(tp->t_state) == 0) { + TCP_REASS(tp, ti, m, so, tiflags); + /* + * 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); + } else { + m_freem(m); + tiflags &= ~TH_FIN; + } + + /* + * If FIN is received ACK the FIN and let the user know + * that the connection is closing. + */ + if (tiflags & TH_FIN) { + if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { + socantrcvmore(so); + tp->t_flags |= TF_ACKNOW; + tp->rcv_nxt++; + } + switch (tp->t_state) { + + /* + * In SYN_RECEIVED and ESTABLISHED STATES + * enter the CLOSE_WAIT state. + */ + case TCPS_SYN_RECEIVED: + case TCPS_ESTABLISHED: + tp->t_state = TCPS_CLOSE_WAIT; + break; + + /* + * If still in FIN_WAIT_1 STATE FIN has not been acked so + * enter the CLOSING state. + */ + case TCPS_FIN_WAIT_1: + tp->t_state = TCPS_CLOSING; + break; + + /* + * In FIN_WAIT_2 state enter the TIME_WAIT state, + * starting the time-wait timer, turning off the other + * standard timers. + */ + case TCPS_FIN_WAIT_2: + tp->t_state = TCPS_TIME_WAIT; + tcp_canceltimers(tp); + tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; + soisdisconnected(so); + break; + + /* + * In TIME_WAIT state restart the 2 MSL time_wait timer. + */ + case TCPS_TIME_WAIT: + tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; + break; + } + } + if (so->so_options & SO_DEBUG) + tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); + + /* + * Return any desired output. + */ + if (needoutput || (tp->t_flags & TF_ACKNOW)) + (void) tcp_output(tp); + return; + +dropafterack: + /* + * Generate an ACK dropping incoming segment if it occupies + * sequence space, where the ACK reflects our state. + */ + if (tiflags & TH_RST) + goto drop; + m_freem(m); + tp->t_flags |= TF_ACKNOW; + (void) tcp_output(tp); + return; + +dropwithreset: + /* + * Generate a RST, dropping incoming segment. + * Make ACK acceptable to originator of segment. + * Don't bother to respond if destination was broadcast/multicast. + */ + if ((tiflags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST) || + IN_MULTICAST(ti->ti_dst.s_addr)) + goto drop; + if (tiflags & TH_ACK) + tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST); + else { + if (tiflags & TH_SYN) + ti->ti_len++; + tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0, + TH_RST|TH_ACK); + } + /* destroy temporarily created socket */ + if (dropsocket) + (void) soabort(so); + return; + +drop: + /* + * 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; +#ifndef TUBA_INCLUDE +} + +void +tcp_dooptions(tp, cp, cnt, ti, ts_present, ts_val, ts_ecr) + struct tcpcb *tp; + u_char *cp; + int cnt; + struct tcpiphdr *ti; + int *ts_present; + u_long *ts_val, *ts_ecr; +{ + u_short mss; + int opt, optlen; + + 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) { + + default: + continue; + + case TCPOPT_MAXSEG: + if (optlen != TCPOLEN_MAXSEG) + continue; + if (!(ti->ti_flags & TH_SYN)) + continue; + bcopy((char *) cp + 2, (char *) &mss, sizeof(mss)); + NTOHS(mss); + (void) tcp_mss(tp, mss); /* sets t_maxseg */ + break; + + case TCPOPT_WINDOW: + if (optlen != TCPOLEN_WINDOW) + continue; + if (!(ti->ti_flags & TH_SYN)) + continue; + tp->t_flags |= TF_RCVD_SCALE; + tp->requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT); + break; + + case TCPOPT_TIMESTAMP: + if (optlen != TCPOLEN_TIMESTAMP) + continue; + *ts_present = 1; + bcopy((char *)cp + 2, (char *) ts_val, sizeof(*ts_val)); + NTOHL(*ts_val); + bcopy((char *)cp + 6, (char *) ts_ecr, sizeof(*ts_ecr)); + NTOHL(*ts_ecr); + + /* + * A timestamp received in a SYN makes + * it ok to send timestamp requests and replies. + */ + if (ti->ti_flags & TH_SYN) { + tp->t_flags |= TF_RCVD_TSTMP; + tp->ts_recent = *ts_val; + tp->ts_recent_age = tcp_now; + } + 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. + */ +void +tcp_pulloutofband(so, ti, m) + struct socket *so; + struct tcpiphdr *ti; + register struct mbuf *m; +{ + int cnt = ti->ti_urp - 1; + + 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; + } + cnt -= m->m_len; + m = m->m_next; + if (m == 0) + break; + } + panic("tcp_pulloutofband"); +} + +/* + * Collect new round-trip time estimate + * and update averages and current timeout. + */ +void +tcp_xmit_timer(tp, rtt) + register struct tcpcb *tp; + short rtt; +{ + register short delta; + + tcpstat.tcps_rttupdated++; + if (tp->t_srtt != 0) { + /* + * 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 rtt to origin 0. + */ + delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT); + 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 + 4 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 >> TCP_RTTVAR_SHIFT); + 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 3*rtt). + */ + tp->t_srtt = rtt << TCP_RTT_SHIFT; + tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); + } + tp->t_rtt = 0; + tp->t_rxtshift = 0; + + /* + * the retransmit should happen at rtt + 4 * rttvar. + * Because of the way we do the smoothing, srtt and rttvar + * will each average +1/2 tick of bias. When we compute + * the retransmit timer, we want 1/2 tick of rounding and + * 1 extra tick because of +-1/2 tick uncertainty in the + * firing of the timer. The bias will give us exactly the + * 1.5 tick we need. But, because the bias is + * statistical, we have to test that we don't drop below + * the minimum feasible timer (which is 2 ticks). + */ + TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), + tp->t_rttmin, TCPTV_REXMTMAX); + + /* + * We received an ack for a packet that wasn't retransmitted; + * it is probably safe to discard any error indications we've + * received recently. This isn't quite right, but close enough + * for now (a route might have failed after we sent a segment, + * and the return path might not be symmetrical). + */ + tp->t_softerror = 0; +} + +/* + * Determine a reasonable value for maxseg size. + * If the route is known, check route for mtu. + * If none, use an mss that can be handled on the outgoing + * interface without forcing IP to fragment; if bigger than + * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES + * to utilize large mbufs. If no route is found, route has no mtu, + * or the destination isn't local, use a default, hopefully conservative + * size (usually 512 or the default IP max size, but no more than the mtu + * of the interface), 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. + * While looking at the routing entry, we also initialize other path-dependent + * parameters from pre-set or cached values in the routing entry. + */ +int +tcp_mss(tp, offer) + register struct tcpcb *tp; + u_int offer; +{ + struct route *ro; + register struct rtentry *rt; + struct ifnet *ifp; + register int rtt, mss; + u_long bufsize; + struct inpcb *inp; + struct socket *so; + extern int tcp_mssdflt; + + inp = tp->t_inpcb; + ro = &inp->inp_route; + + if ((rt = ro->ro_rt) == (struct rtentry *)0) { + /* No route yet, so try to acquire one */ + if (inp->inp_faddr.s_addr != INADDR_ANY) { + ro->ro_dst.sa_family = AF_INET; + ro->ro_dst.sa_len = sizeof(ro->ro_dst); + ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = + inp->inp_faddr; + rtalloc(ro); + } + if ((rt = ro->ro_rt) == (struct rtentry *)0) + return (tcp_mssdflt); + } + ifp = rt->rt_ifp; + so = inp->inp_socket; + +#ifdef RTV_MTU /* if route characteristics exist ... */ + /* + * While we're here, check if there's an initial rtt + * or rttvar. Convert from the route-table units + * to scaled multiples of the slow timeout timer. + */ + if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) { + /* + * XXX the lock bit for MTU indicates that the value + * is also a minimum value; this is subject to time. + */ + if (rt->rt_rmx.rmx_locks & RTV_RTT) + tp->t_rttmin = rtt / (RTM_RTTUNIT / PR_SLOWHZ); + tp->t_srtt = rtt / (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); + if (rt->rt_rmx.rmx_rttvar) + tp->t_rttvar = rt->rt_rmx.rmx_rttvar / + (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); + else + /* default variation is +- 1 rtt */ + tp->t_rttvar = + tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; + TCPT_RANGESET(tp->t_rxtcur, + ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, + tp->t_rttmin, TCPTV_REXMTMAX); + } + /* + * if there's an mtu associated with the route, use it + */ + if (rt->rt_rmx.rmx_mtu) + mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr); + else +#endif /* RTV_MTU */ + { + 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)) + mss = min(mss, tcp_mssdflt); + } + /* + * The current mss, t_maxseg, is initialized to the default value. + * If we compute a smaller value, reduce the current mss. + * If we compute a larger value, return it for use in sending + * a max seg size option, but don't store it for use + * unless we received an offer at least that large from peer. + * However, do not accept offers under 32 bytes. + */ + if (offer) + mss = min(mss, offer); + mss = max(mss, 32); /* sanity */ + if (mss < tp->t_maxseg || offer != 0) { + /* + * If there's a pipesize, change the socket buffer + * to that size. Make the socket buffers an integral + * number of mss units; if the mss is larger than + * the socket buffer, decrease the mss. + */ +#ifdef RTV_SPIPE + if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0) +#endif + bufsize = so->so_snd.sb_hiwat; + if (bufsize < mss) + mss = bufsize; + else { + bufsize = roundup(bufsize, mss); + if (bufsize > sb_max) + bufsize = sb_max; + (void)sbreserve(&so->so_snd, bufsize); + } + tp->t_maxseg = mss; + +#ifdef RTV_RPIPE + if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0) +#endif + bufsize = so->so_rcv.sb_hiwat; + if (bufsize > mss) { + bufsize = roundup(bufsize, mss); + if (bufsize > sb_max) + bufsize = sb_max; + (void)sbreserve(&so->so_rcv, bufsize); + } + } + tp->snd_cwnd = mss; + +#ifdef RTV_SSTHRESH + if (rt->rt_rmx.rmx_ssthresh) { + /* + * There's some sort of gateway or interface + * buffer limit on the path. Use this to set + * the slow start threshhold, but set the + * threshold to no less than 2*mss. + */ + tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); + } +#endif /* RTV_MTU */ + return (mss); +} +#endif /* TUBA_INCLUDE */ diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c new file mode 100644 index 0000000..8edb853 --- /dev/null +++ b/sys/netinet/tcp_timewait.c @@ -0,0 +1,445 @@ +/* + * Copyright (c) 1982, 1986, 1988, 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * @(#)tcp_subr.c 8.1 (Berkeley) 6/10/93 + */ + +#include <sys/param.h> +#include <sys/proc.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/protosw.h> +#include <sys/errno.h> + +#include <net/route.h> +#include <net/if.h> + +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/in_pcb.h> +#include <netinet/ip_var.h> +#include <netinet/ip_icmp.h> +#include <netinet/tcp.h> +#include <netinet/tcp_fsm.h> +#include <netinet/tcp_seq.h> +#include <netinet/tcp_timer.h> +#include <netinet/tcp_var.h> +#include <netinet/tcpip.h> + +/* patchable/settable parameters for tcp */ +int tcp_mssdflt = TCP_MSS; +int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; +int tcp_do_rfc1323 = 1; + +extern struct inpcb *tcp_last_inpcb; + +/* + * Tcp initialization + */ +void +tcp_init() +{ + + tcp_iss = 1; /* wrong */ + tcb.inp_next = tcb.inp_prev = &tcb; + if (max_protohdr < sizeof(struct tcpiphdr)) + max_protohdr = sizeof(struct tcpiphdr); + if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) + panic("tcp_init"); +} + +/* + * Create template to be used to send tcp packets on a connection. + * Call after host entry created, allocates an mbuf and fills + * in a skeletal tcp/ip header, minimizing the amount of work + * necessary when the connection is used. + */ +struct tcpiphdr * +tcp_template(tp) + struct tcpcb *tp; +{ + register struct inpcb *inp = tp->t_inpcb; + register struct mbuf *m; + register struct tcpiphdr *n; + + if ((n = tp->t_template) == 0) { + m = m_get(M_DONTWAIT, MT_HEADER); + if (m == NULL) + return (0); + m->m_len = sizeof (struct tcpiphdr); + n = mtod(m, struct tcpiphdr *); + } + n->ti_next = n->ti_prev = 0; + n->ti_x1 = 0; + n->ti_pr = IPPROTO_TCP; + n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); + n->ti_src = inp->inp_laddr; + n->ti_dst = inp->inp_faddr; + n->ti_sport = inp->inp_lport; + n->ti_dport = inp->inp_fport; + n->ti_seq = 0; + n->ti_ack = 0; + n->ti_x2 = 0; + n->ti_off = 5; + n->ti_flags = 0; + n->ti_win = 0; + n->ti_sum = 0; + n->ti_urp = 0; + return (n); +} + +/* + * Send a single message to the TCP at address specified by + * the given TCP/IP header. If m == 0, then we make a copy + * of the tcpiphdr at ti and send directly to the addressed host. + * This is used to force keep alive messages out using the TCP + * template for a connection tp->t_template. If flags are given + * then we send a message back to the TCP which originated the + * segment ti, and discard the mbuf containing it and any other + * attached mbufs. + * + * In any case the ack and sequence number of the transmitted + * segment are as specified by the parameters. + */ +void +tcp_respond(tp, ti, m, ack, seq, flags) + struct tcpcb *tp; + register struct tcpiphdr *ti; + register struct mbuf *m; + tcp_seq ack, seq; + int flags; +{ + register int tlen; + int win = 0; + struct route *ro = 0; + + if (tp) { + win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); + ro = &tp->t_inpcb->inp_route; + } + if (m == 0) { + m = m_gethdr(M_DONTWAIT, MT_HEADER); + if (m == NULL) + return; +#ifdef TCP_COMPAT_42 + tlen = 1; +#else + tlen = 0; +#endif + m->m_data += max_linkhdr; + *mtod(m, struct tcpiphdr *) = *ti; + ti = mtod(m, struct tcpiphdr *); + flags = TH_ACK; + } else { + m_freem(m->m_next); + m->m_next = 0; + m->m_data = (caddr_t)ti; + m->m_len = sizeof (struct tcpiphdr); + tlen = 0; +#define xchg(a,b,type) { type t; t=a; a=b; b=t; } + xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); + xchg(ti->ti_dport, ti->ti_sport, u_short); +#undef xchg + } + ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); + tlen += sizeof (struct tcpiphdr); + m->m_len = tlen; + m->m_pkthdr.len = tlen; + m->m_pkthdr.rcvif = (struct ifnet *) 0; + ti->ti_next = ti->ti_prev = 0; + ti->ti_x1 = 0; + ti->ti_seq = htonl(seq); + ti->ti_ack = htonl(ack); + ti->ti_x2 = 0; + ti->ti_off = sizeof (struct tcphdr) >> 2; + ti->ti_flags = flags; + if (tp) + ti->ti_win = htons((u_short) (win >> tp->rcv_scale)); + else + ti->ti_win = htons((u_short)win); + ti->ti_urp = 0; + ti->ti_sum = 0; + ti->ti_sum = in_cksum(m, tlen); + ((struct ip *)ti)->ip_len = tlen; + ((struct ip *)ti)->ip_ttl = ip_defttl; + (void) ip_output(m, NULL, ro, 0, NULL); +} + +/* + * Create a new TCP control block, making an + * empty reassembly queue and hooking it to the argument + * protocol control block. + */ +struct tcpcb * +tcp_newtcpcb(inp) + struct inpcb *inp; +{ + register struct tcpcb *tp; + + tp = malloc(sizeof(*tp), M_PCB, M_NOWAIT); + if (tp == NULL) + return ((struct tcpcb *)0); + bzero((char *) tp, sizeof(struct tcpcb)); + tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; + tp->t_maxseg = tcp_mssdflt; + + tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; + tp->t_inpcb = inp; + /* + * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no + * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives + * reasonable initial retransmit time. + */ + tp->t_srtt = TCPTV_SRTTBASE; + tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << 2; + tp->t_rttmin = TCPTV_MIN; + TCPT_RANGESET(tp->t_rxtcur, + ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1, + TCPTV_MIN, TCPTV_REXMTMAX); + tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; + tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; + inp->inp_ip.ip_ttl = ip_defttl; + inp->inp_ppcb = (caddr_t)tp; + return (tp); +} + +/* + * Drop a TCP connection, reporting + * the specified error. If connection is synchronized, + * then send a RST to peer. + */ +struct tcpcb * +tcp_drop(tp, errno) + register struct tcpcb *tp; + int errno; +{ + struct socket *so = tp->t_inpcb->inp_socket; + + if (TCPS_HAVERCVDSYN(tp->t_state)) { + tp->t_state = TCPS_CLOSED; + (void) tcp_output(tp); + tcpstat.tcps_drops++; + } else + tcpstat.tcps_conndrops++; + if (errno == ETIMEDOUT && tp->t_softerror) + errno = tp->t_softerror; + so->so_error = errno; + return (tcp_close(tp)); +} + +/* + * Close a TCP control block: + * discard all space held by the tcp + * discard internet protocol block + * wake up any sleepers + */ +struct tcpcb * +tcp_close(tp) + register struct tcpcb *tp; +{ + register struct tcpiphdr *t; + struct inpcb *inp = tp->t_inpcb; + struct socket *so = inp->inp_socket; + register struct mbuf *m; +#ifdef RTV_RTT + register struct rtentry *rt; + + /* + * If we sent enough data to get some meaningful characteristics, + * save them in the routing entry. 'Enough' is arbitrarily + * defined as the sendpipesize (default 4K) * 16. This would + * give us 16 rtt samples assuming we only get one sample per + * window (the usual case on a long haul net). 16 samples is + * enough for the srtt filter to converge to within 5% of the correct + * value; fewer samples and we could save a very bogus rtt. + * + * Don't update the default route's characteristics and don't + * update anything that the user "locked". + */ + if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) && + (rt = inp->inp_route.ro_rt) && + ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) { + register u_long i; + + if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { + i = tp->t_srtt * + (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); + if (rt->rt_rmx.rmx_rtt && i) + /* + * filter this update to half the old & half + * the new values, converting scale. + * See route.h and tcp_var.h for a + * description of the scaling constants. + */ + rt->rt_rmx.rmx_rtt = + (rt->rt_rmx.rmx_rtt + i) / 2; + else + rt->rt_rmx.rmx_rtt = i; + } + if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { + i = tp->t_rttvar * + (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); + if (rt->rt_rmx.rmx_rttvar && i) + rt->rt_rmx.rmx_rttvar = + (rt->rt_rmx.rmx_rttvar + i) / 2; + else + rt->rt_rmx.rmx_rttvar = i; + } + /* + * update the pipelimit (ssthresh) if it has been updated + * already or if a pipesize was specified & the threshhold + * got below half the pipesize. I.e., wait for bad news + * before we start updating, then update on both good + * and bad news. + */ + if ((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && + (i = tp->snd_ssthresh) && rt->rt_rmx.rmx_ssthresh || + i < (rt->rt_rmx.rmx_sendpipe / 2)) { + /* + * convert the limit from user data bytes to + * packets then to packet data bytes. + */ + i = (i + tp->t_maxseg / 2) / tp->t_maxseg; + if (i < 2) + i = 2; + i *= (u_long)(tp->t_maxseg + sizeof (struct tcpiphdr)); + if (rt->rt_rmx.rmx_ssthresh) + rt->rt_rmx.rmx_ssthresh = + (rt->rt_rmx.rmx_ssthresh + i) / 2; + else + rt->rt_rmx.rmx_ssthresh = i; + } + } +#endif /* RTV_RTT */ + /* free the reassembly queue, if any */ + t = tp->seg_next; + while (t != (struct tcpiphdr *)tp) { + t = (struct tcpiphdr *)t->ti_next; + m = REASS_MBUF((struct tcpiphdr *)t->ti_prev); + remque(t->ti_prev); + m_freem(m); + } + if (tp->t_template) + (void) m_free(dtom(tp->t_template)); + free(tp, M_PCB); + inp->inp_ppcb = 0; + soisdisconnected(so); + /* clobber input pcb cache if we're closing the cached connection */ + if (inp == tcp_last_inpcb) + tcp_last_inpcb = &tcb; + in_pcbdetach(inp); + tcpstat.tcps_closed++; + return ((struct tcpcb *)0); +} + +void +tcp_drain() +{ + +} + +/* + * Notify a tcp user of an asynchronous error; + * store error as soft error, but wake up user + * (for now, won't do anything until can select for soft error). + */ +void +tcp_notify(inp, error) + struct inpcb *inp; + int error; +{ + register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; + register struct socket *so = inp->inp_socket; + + /* + * Ignore some errors if we are hooked up. + * If connection hasn't completed, has retransmitted several times, + * and receives a second error, give up now. This is better + * than waiting a long time to establish a connection that + * can never complete. + */ + if (tp->t_state == TCPS_ESTABLISHED && + (error == EHOSTUNREACH || error == ENETUNREACH || + error == EHOSTDOWN)) { + return; + } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && + tp->t_softerror) + so->so_error = error; + else + tp->t_softerror = error; + wakeup((caddr_t) &so->so_timeo); + sorwakeup(so); + sowwakeup(so); +} + +void +tcp_ctlinput(cmd, sa, ip) + int cmd; + struct sockaddr *sa; + register struct ip *ip; +{ + register struct tcphdr *th; + extern struct in_addr zeroin_addr; + extern u_char inetctlerrmap[]; + void (*notify) __P((struct inpcb *, int)) = tcp_notify; + + if (cmd == PRC_QUENCH) + notify = tcp_quench; + else if (!PRC_IS_REDIRECT(cmd) && + ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0)) + return; + if (ip) { + th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2)); + in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport, + cmd, notify); + } else + in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, notify); +} + +/* + * When a source quench is received, close congestion window + * to one segment. We will gradually open it again as we proceed. + */ +void +tcp_quench(inp, errno) + struct inpcb *inp; + int errno; +{ + struct tcpcb *tp = intotcpcb(inp); + + if (tp) + tp->snd_cwnd = tp->t_maxseg; +} |
