| /* | |
| * 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. 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 | |
| * tcp_input.c,v 1.10 1994/10/13 18:36:32 wollman Exp | |
| */ | |
| /* | |
| * Changes and additions relating to SLiRP | |
| * Copyright (c) 1995 Danny Gasparovski. | |
| * | |
| * Please read the file COPYRIGHT for the | |
| * terms and conditions of the copyright. | |
| */ | |
| #include <slirp.h> | |
| #include "ip_icmp.h" | |
| #define TCPREXMTTHRESH 3 | |
| #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). | |
| */ | |
| #ifdef TCP_ACK_HACK | |
| #define TCP_REASS(tp, ti, m, so, flags) {\ | |
| if ((ti)->ti_seq == (tp)->rcv_nxt && \ | |
| tcpfrag_list_empty(tp) && \ | |
| (tp)->t_state == TCPS_ESTABLISHED) {\ | |
| if (ti->ti_flags & TH_PUSH) \ | |
| tp->t_flags |= TF_ACKNOW; \ | |
| else \ | |
| tp->t_flags |= TF_DELACK; \ | |
| (tp)->rcv_nxt += (ti)->ti_len; \ | |
| flags = (ti)->ti_flags & TH_FIN; \ | |
| if (so->so_emu) { \ | |
| if (tcp_emu((so),(m))) sbappend((so), (m)); \ | |
| } else \ | |
| sbappend((so), (m)); \ | |
| } else {\ | |
| (flags) = tcp_reass((tp), (ti), (m)); \ | |
| tp->t_flags |= TF_ACKNOW; \ | |
| } \ | |
| } | |
| #else | |
| #define TCP_REASS(tp, ti, m, so, flags) { \ | |
| if ((ti)->ti_seq == (tp)->rcv_nxt && \ | |
| tcpfrag_list_empty(tp) && \ | |
| (tp)->t_state == TCPS_ESTABLISHED) { \ | |
| tp->t_flags |= TF_DELACK; \ | |
| (tp)->rcv_nxt += (ti)->ti_len; \ | |
| flags = (ti)->ti_flags & TH_FIN; \ | |
| if (so->so_emu) { \ | |
| if (tcp_emu((so),(m))) sbappend(so, (m)); \ | |
| } else \ | |
| sbappend((so), (m)); \ | |
| } else { \ | |
| (flags) = tcp_reass((tp), (ti), (m)); \ | |
| tp->t_flags |= TF_ACKNOW; \ | |
| } \ | |
| } | |
| #endif | |
| static void tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, | |
| struct tcpiphdr *ti); | |
| static void tcp_xmit_timer(register struct tcpcb *tp, int rtt); | |
| static int | |
| tcp_reass(register struct tcpcb *tp, register struct tcpiphdr *ti, | |
| struct mbuf *m) | |
| { | |
| register struct tcpiphdr *q; | |
| struct socket *so = tp->t_socket; | |
| int flags; | |
| /* | |
| * Call with ti==NULL after become established to | |
| * force pre-ESTABLISHED data up to user socket. | |
| */ | |
| if (ti == NULL) | |
| goto present; | |
| /* | |
| * Find a segment which begins after this one does. | |
| */ | |
| for (q = tcpfrag_list_first(tp); !tcpfrag_list_end(q, tp); | |
| q = tcpiphdr_next(q)) | |
| 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 (!tcpfrag_list_end(tcpiphdr_prev(q), tp)) { | |
| register int i; | |
| q = tcpiphdr_prev(q); | |
| /* 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) { | |
| m_free(m); | |
| /* | |
| * Try to present any queued data | |
| * at the left window edge to the user. | |
| * This is needed after the 3-WHS | |
| * completes. | |
| */ | |
| goto present; /* ??? */ | |
| } | |
| m_adj(m, i); | |
| ti->ti_len -= i; | |
| ti->ti_seq += i; | |
| } | |
| q = tcpiphdr_next(q); | |
| } | |
| ti->ti_mbuf = m; | |
| /* | |
| * While we overlap succeeding segments trim them or, | |
| * if they are completely covered, dequeue them. | |
| */ | |
| while (!tcpfrag_list_end(q, 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(q->ti_mbuf, i); | |
| break; | |
| } | |
| q = tcpiphdr_next(q); | |
| m = tcpiphdr_prev(q)->ti_mbuf; | |
| remque(tcpiphdr2qlink(tcpiphdr_prev(q))); | |
| m_free(m); | |
| } | |
| /* | |
| * Stick new segment in its place. | |
| */ | |
| insque(tcpiphdr2qlink(ti), tcpiphdr2qlink(tcpiphdr_prev(q))); | |
| present: | |
| /* | |
| * Present data to user, advancing rcv_nxt through | |
| * completed sequence space. | |
| */ | |
| if (!TCPS_HAVEESTABLISHED(tp->t_state)) | |
| return (0); | |
| ti = tcpfrag_list_first(tp); | |
| if (tcpfrag_list_end(ti, 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(tcpiphdr2qlink(ti)); | |
| m = ti->ti_mbuf; | |
| ti = tcpiphdr_next(ti); | |
| if (so->so_state & SS_FCANTSENDMORE) | |
| m_free(m); | |
| else { | |
| if (so->so_emu) { | |
| if (tcp_emu(so,m)) sbappend(so, m); | |
| } else | |
| sbappend(so, m); | |
| } | |
| } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); | |
| return (flags); | |
| } | |
| /* | |
| * TCP input routine, follows pages 65-76 of the | |
| * protocol specification dated September, 1981 very closely. | |
| */ | |
| void | |
| tcp_input(struct mbuf *m, int iphlen, struct socket *inso) | |
| { | |
| struct ip save_ip, *ip; | |
| register struct tcpiphdr *ti; | |
| caddr_t optp = NULL; | |
| int optlen = 0; | |
| int len, tlen, off; | |
| register struct tcpcb *tp = NULL; | |
| register int tiflags; | |
| struct socket *so = NULL; | |
| int todrop, acked, ourfinisacked, needoutput = 0; | |
| int iss = 0; | |
| u_long tiwin; | |
| int ret; | |
| struct ex_list *ex_ptr; | |
| Slirp *slirp; | |
| DEBUG_CALL("tcp_input"); | |
| DEBUG_ARGS(" m = %8lx iphlen = %2d inso = %lx\n", | |
| (long )m, iphlen, (long )inso ); | |
| /* | |
| * If called with m == 0, then we're continuing the connect | |
| */ | |
| if (m == NULL) { | |
| so = inso; | |
| slirp = so->slirp; | |
| /* Re-set a few variables */ | |
| tp = sototcpcb(so); | |
| m = so->so_m; | |
| so->so_m = NULL; | |
| ti = so->so_ti; | |
| tiwin = ti->ti_win; | |
| tiflags = ti->ti_flags; | |
| goto cont_conn; | |
| } | |
| slirp = m->slirp; | |
| /* | |
| * 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); | |
| iphlen=sizeof(struct ip ); | |
| } | |
| /* XXX Check if too short */ | |
| /* | |
| * Save a copy of the IP header in case we want restore it | |
| * for sending an ICMP error message in response. | |
| */ | |
| ip=mtod(m, struct ip *); | |
| save_ip = *ip; | |
| save_ip.ip_len+= iphlen; | |
| /* | |
| * Checksum extended TCP header and data. | |
| */ | |
| tlen = ((struct ip *)ti)->ip_len; | |
| tcpiphdr2qlink(ti)->next = tcpiphdr2qlink(ti)->prev = NULL; | |
| memset(&ti->ti_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr)); | |
| ti->ti_x1 = 0; | |
| ti->ti_len = htons((uint16_t)tlen); | |
| len = sizeof(struct ip ) + tlen; | |
| if(cksum(m, len)) { | |
| goto drop; | |
| } | |
| /* | |
| * 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) { | |
| goto drop; | |
| } | |
| tlen -= off; | |
| ti->ti_len = tlen; | |
| if (off > sizeof (struct tcphdr)) { | |
| optlen = off - sizeof (struct tcphdr); | |
| optp = mtod(m, caddr_t) + sizeof (struct tcpiphdr); | |
| } | |
| 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); | |
| /* | |
| * 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); | |
| /* | |
| * Locate pcb for segment. | |
| */ | |
| findso: | |
| so = slirp->tcp_last_so; | |
| if (so->so_fport != ti->ti_dport || | |
| so->so_lport != ti->ti_sport || | |
| so->so_laddr.s_addr != ti->ti_src.s_addr || | |
| so->so_faddr.s_addr != ti->ti_dst.s_addr) { | |
| so = solookup(&slirp->tcb, ti->ti_src, ti->ti_sport, | |
| ti->ti_dst, ti->ti_dport); | |
| if (so) | |
| slirp->tcp_last_so = so; | |
| } | |
| /* | |
| * 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. | |
| * | |
| * state == CLOSED means we've done socreate() but haven't | |
| * attached it to a protocol yet... | |
| * | |
| * XXX If a TCB does not exist, and the TH_SYN flag is | |
| * the only flag set, then create a session, mark it | |
| * as if it was LISTENING, and continue... | |
| */ | |
| if (so == NULL) { | |
| if (slirp->restricted) { | |
| /* Any hostfwds will have an existing socket, so we only get here | |
| * for non-hostfwd connections. These should be dropped, unless it | |
| * happens to be a guestfwd. | |
| */ | |
| for (ex_ptr = slirp->exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) { | |
| if (ex_ptr->ex_fport == ti->ti_dport && | |
| ti->ti_dst.s_addr == ex_ptr->ex_addr.s_addr) { | |
| break; | |
| } | |
| } | |
| if (!ex_ptr) { | |
| goto dropwithreset; | |
| } | |
| } | |
| if ((tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) != TH_SYN) | |
| goto dropwithreset; | |
| if ((so = socreate(slirp)) == NULL) | |
| goto dropwithreset; | |
| if (tcp_attach(so) < 0) { | |
| free(so); /* Not sofree (if it failed, it's not insqued) */ | |
| goto dropwithreset; | |
| } | |
| sbreserve(&so->so_snd, TCP_SNDSPACE); | |
| sbreserve(&so->so_rcv, TCP_RCVSPACE); | |
| so->so_laddr = ti->ti_src; | |
| so->so_lport = ti->ti_sport; | |
| so->so_faddr = ti->ti_dst; | |
| so->so_fport = ti->ti_dport; | |
| if ((so->so_iptos = tcp_tos(so)) == 0) | |
| so->so_iptos = ((struct ip *)ti)->ip_tos; | |
| tp = sototcpcb(so); | |
| tp->t_state = TCPS_LISTEN; | |
| } | |
| /* | |
| * If this is a still-connecting socket, this probably | |
| * a retransmit of the SYN. Whether it's a retransmit SYN | |
| * or something else, we nuke it. | |
| */ | |
| if (so->so_state & SS_ISFCONNECTING) | |
| goto drop; | |
| tp = sototcpcb(so); | |
| /* XXX Should never fail */ | |
| if (tp == NULL) | |
| goto dropwithreset; | |
| if (tp->t_state == TCPS_CLOSED) | |
| goto drop; | |
| tiwin = ti->ti_win; | |
| /* | |
| * Segment received on connection. | |
| * Reset idle time and keep-alive timer. | |
| */ | |
| tp->t_idle = 0; | |
| if (SO_OPTIONS) | |
| tp->t_timer[TCPT_KEEP] = TCPTV_KEEPINTVL; | |
| else | |
| tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_IDLE; | |
| /* | |
| * 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, (u_char *)optp, optlen, ti); | |
| /* | |
| * 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. | |
| * | |
| * XXX Some of these tests are not needed | |
| * eg: the tiwin == tp->snd_wnd prevents many more | |
| * predictions.. with no *real* advantage.. | |
| */ | |
| if (tp->t_state == TCPS_ESTABLISHED && | |
| (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && | |
| ti->ti_seq == tp->rcv_nxt && | |
| tiwin && tiwin == tp->snd_wnd && | |
| tp->snd_nxt == tp->snd_max) { | |
| 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. | |
| */ | |
| 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; | |
| sbdrop(&so->so_snd, acked); | |
| tp->snd_una = ti->ti_ack; | |
| m_free(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; | |
| /* | |
| * This is called because sowwakeup might have | |
| * put data into so_snd. Since we don't so sowwakeup, | |
| * we don't need this.. XXX??? | |
| */ | |
| if (so->so_snd.sb_cc) | |
| (void) tcp_output(tp); | |
| return; | |
| } | |
| } else if (ti->ti_ack == tp->snd_una && | |
| tcpfrag_list_empty(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. | |
| */ | |
| tp->rcv_nxt += ti->ti_len; | |
| /* | |
| * Add data to socket buffer. | |
| */ | |
| if (so->so_emu) { | |
| if (tcp_emu(so,m)) sbappend(so, m); | |
| } else | |
| sbappend(so, m); | |
| /* | |
| * If this is a short packet, then ACK now - with Nagel | |
| * congestion avoidance sender won't send more until | |
| * he gets an ACK. | |
| * | |
| * It is better to not delay acks at all to maximize | |
| * TCP throughput. See RFC 2581. | |
| */ | |
| tp->t_flags |= TF_ACKNOW; | |
| tcp_output(tp); | |
| return; | |
| } | |
| } /* header prediction */ | |
| /* | |
| * 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: { | |
| if (tiflags & TH_RST) | |
| goto drop; | |
| if (tiflags & TH_ACK) | |
| goto dropwithreset; | |
| if ((tiflags & TH_SYN) == 0) | |
| goto drop; | |
| /* | |
| * This has way too many gotos... | |
| * But a bit of spaghetti code never hurt anybody :) | |
| */ | |
| /* | |
| * If this is destined for the control address, then flag to | |
| * tcp_ctl once connected, otherwise connect | |
| */ | |
| if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) == | |
| slirp->vnetwork_addr.s_addr) { | |
| if (so->so_faddr.s_addr != slirp->vhost_addr.s_addr && | |
| so->so_faddr.s_addr != slirp->vnameserver_addr.s_addr) { | |
| /* May be an add exec */ | |
| for (ex_ptr = slirp->exec_list; ex_ptr; | |
| ex_ptr = ex_ptr->ex_next) { | |
| if(ex_ptr->ex_fport == so->so_fport && | |
| so->so_faddr.s_addr == ex_ptr->ex_addr.s_addr) { | |
| so->so_state |= SS_CTL; | |
| break; | |
| } | |
| } | |
| if (so->so_state & SS_CTL) { | |
| goto cont_input; | |
| } | |
| } | |
| /* CTL_ALIAS: Do nothing, tcp_fconnect will be called on it */ | |
| } | |
| if (so->so_emu & EMU_NOCONNECT) { | |
| so->so_emu &= ~EMU_NOCONNECT; | |
| goto cont_input; | |
| } | |
| if ((tcp_fconnect(so) == -1) && | |
| #if defined(_WIN32) | |
| socket_error() != WSAEINPROGRESS && socket_error() != WSAEWOULDBLOCK | |
| #else | |
| (errno != EINPROGRESS) && (errno != EWOULDBLOCK) | |
| #endif | |
| ) { | |
| u_char code=ICMP_UNREACH_NET; | |
| DEBUG_MISC(" tcp fconnect errno = %d-%s\n", | |
| errno,strerror(errno)); | |
| if(errno == ECONNREFUSED) { | |
| /* ACK the SYN, send RST to refuse the connection */ | |
| tcp_respond(tp, ti, m, ti->ti_seq+1, (tcp_seq)0, | |
| TH_RST|TH_ACK); | |
| } else { | |
| if(errno == EHOSTUNREACH) code=ICMP_UNREACH_HOST; | |
| HTONL(ti->ti_seq); /* restore tcp header */ | |
| HTONL(ti->ti_ack); | |
| HTONS(ti->ti_win); | |
| HTONS(ti->ti_urp); | |
| m->m_data -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); | |
| m->m_len += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); | |
| *ip=save_ip; | |
| icmp_error(m, ICMP_UNREACH,code, 0,strerror(errno)); | |
| } | |
| tcp_close(tp); | |
| m_free(m); | |
| } else { | |
| /* | |
| * Haven't connected yet, save the current mbuf | |
| * and ti, and return | |
| * XXX Some OS's don't tell us whether the connect() | |
| * succeeded or not. So we must time it out. | |
| */ | |
| so->so_m = m; | |
| so->so_ti = ti; | |
| tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT; | |
| tp->t_state = TCPS_SYN_RECEIVED; | |
| tcp_template(tp); | |
| } | |
| return; | |
| cont_conn: | |
| /* m==NULL | |
| * Check if the connect succeeded | |
| */ | |
| if (so->so_state & SS_NOFDREF) { | |
| tp = tcp_close(tp); | |
| goto dropwithreset; | |
| } | |
| cont_input: | |
| tcp_template(tp); | |
| if (optp) | |
| tcp_dooptions(tp, (u_char *)optp, optlen, ti); | |
| if (iss) | |
| tp->iss = iss; | |
| else | |
| tp->iss = slirp->tcp_iss; | |
| slirp->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; | |
| goto trimthenstep6; | |
| } /* case TCPS_LISTEN */ | |
| /* | |
| * 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) { | |
| tcp_drop(tp, 0); /* XXX Check t_softerror! */ | |
| } | |
| 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)) { | |
| soisfconnected(so); | |
| tp->t_state = TCPS_ESTABLISHED; | |
| (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; | |
| } | |
| tp->snd_wl1 = ti->ti_seq - 1; | |
| tp->rcv_up = ti->ti_seq; | |
| goto step6; | |
| } /* switch tp->t_state */ | |
| /* | |
| * States other than LISTEN or SYN_SENT. | |
| * 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. | |
| */ | |
| 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--; | |
| } | |
| /* | |
| * Following if statement from Stevens, vol. 2, p. 960. | |
| */ | |
| if (todrop > ti->ti_len | |
| || (todrop == ti->ti_len && (tiflags & TH_FIN) == 0)) { | |
| /* | |
| * Any valid FIN must be to the left of the window. | |
| * At this point the FIN must be a duplicate or out | |
| * of sequence; drop it. | |
| */ | |
| tiflags &= ~TH_FIN; | |
| /* | |
| * Send an ACK to resynchronize and drop any data. | |
| * But keep on processing for RST or ACK. | |
| */ | |
| tp->t_flags |= TF_ACKNOW; | |
| todrop = ti->ti_len; | |
| } | |
| 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); | |
| 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) { | |
| 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; | |
| tp = tcp_close(tp); | |
| goto findso; | |
| } | |
| /* | |
| * 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; | |
| } else { | |
| goto dropafterack; | |
| } | |
| } | |
| m_adj(m, -todrop); | |
| ti->ti_len -= todrop; | |
| tiflags &= ~(TH_PUSH|TH_FIN); | |
| } | |
| /* | |
| * 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: | |
| case TCPS_ESTABLISHED: | |
| case TCPS_FIN_WAIT_1: | |
| case TCPS_FIN_WAIT_2: | |
| case TCPS_CLOSE_WAIT: | |
| tp->t_state = TCPS_CLOSED; | |
| tcp_close(tp); | |
| goto drop; | |
| case TCPS_CLOSING: | |
| case TCPS_LAST_ACK: | |
| case TCPS_TIME_WAIT: | |
| 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,0); | |
| 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. una<=ack<=max | |
| */ | |
| case TCPS_SYN_RECEIVED: | |
| if (SEQ_GT(tp->snd_una, ti->ti_ack) || | |
| SEQ_GT(ti->ti_ack, tp->snd_max)) | |
| goto dropwithreset; | |
| tp->t_state = TCPS_ESTABLISHED; | |
| /* | |
| * The sent SYN is ack'ed with our sequence number +1 | |
| * The first data byte already in the buffer will get | |
| * lost if no correction is made. This is only needed for | |
| * SS_CTL since the buffer is empty otherwise. | |
| * tp->snd_una++; or: | |
| */ | |
| tp->snd_una=ti->ti_ack; | |
| if (so->so_state & SS_CTL) { | |
| /* So tcp_ctl reports the right state */ | |
| ret = tcp_ctl(so); | |
| if (ret == 1) { | |
| soisfconnected(so); | |
| so->so_state &= ~SS_CTL; /* success XXX */ | |
| } else if (ret == 2) { | |
| so->so_state &= SS_PERSISTENT_MASK; | |
| so->so_state |= SS_NOFDREF; /* CTL_CMD */ | |
| } else { | |
| needoutput = 1; | |
| tp->t_state = TCPS_FIN_WAIT_1; | |
| } | |
| } else { | |
| soisfconnected(so); | |
| } | |
| (void) tcp_reass(tp, (struct tcpiphdr *)0, (struct mbuf *)0); | |
| tp->snd_wl1 = ti->ti_seq - 1; | |
| /* Avoid ack processing; snd_una==ti_ack => dup ack */ | |
| goto synrx_to_est; | |
| /* 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) { | |
| DEBUG_MISC(" dup ack m = %lx so = %lx\n", | |
| (long )m, (long )so); | |
| /* | |
| * 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 | |
| * threshold 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; | |
| } | |
| synrx_to_est: | |
| /* | |
| * 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)) { | |
| goto dropafterack; | |
| } | |
| acked = ti->ti_ack - tp->snd_una; | |
| /* | |
| * 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)) | |
| 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). | |
| */ | |
| { | |
| register u_int cw = tp->snd_cwnd; | |
| register u_int incr = tp->t_maxseg; | |
| if (cw > tp->snd_ssthresh) | |
| incr = incr * incr / cw; | |
| tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale); | |
| } | |
| if (acked > (int)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; | |
| } | |
| 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_FCANTRCVMORE) { | |
| 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; | |
| } | |
| 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) { | |
| 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; | |
| } | |
| } /* switch(tp->t_state) */ | |
| 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))))) { | |
| 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 > so->so_rcv.sb_datalen) { | |
| ti->ti_urp = 0; | |
| tiflags &= ~TH_URG; | |
| goto dodata; | |
| } | |
| /* | |
| * 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_urgc = so->so_rcv.sb_cc + | |
| (tp->rcv_up - tp->rcv_nxt); /* -1; */ | |
| tp->rcv_up = ti->ti_seq + ti->ti_urp; | |
| } | |
| } 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: | |
| /* | |
| * If this is a small packet, then ACK now - with Nagel | |
| * congestion avoidance sender won't send more until | |
| * he gets an ACK. | |
| */ | |
| if (ti->ti_len && (unsigned)ti->ti_len <= 5 && | |
| ((struct tcpiphdr_2 *)ti)->first_char == (char)27) { | |
| tp->t_flags |= TF_ACKNOW; | |
| } | |
| /* | |
| * 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); | |
| } else { | |
| m_free(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) { | |
| /* | |
| * If we receive a FIN we can't send more data, | |
| * set it SS_FDRAIN | |
| * Shutdown the socket if there is no rx data in the | |
| * buffer. | |
| * soread() is called on completion of shutdown() and | |
| * will got to TCPS_LAST_ACK, and use tcp_output() | |
| * to send the FIN. | |
| */ | |
| sofwdrain(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: | |
| if(so->so_emu == EMU_CTL) /* no shutdown on socket */ | |
| tp->t_state = TCPS_LAST_ACK; | |
| else | |
| 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; | |
| 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; | |
| } | |
| } | |
| /* | |
| * 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_free(m); | |
| tp->t_flags |= TF_ACKNOW; | |
| (void) tcp_output(tp); | |
| return; | |
| dropwithreset: | |
| /* reuses m if m!=NULL, m_free() unnecessary */ | |
| 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); | |
| } | |
| return; | |
| drop: | |
| /* | |
| * Drop space held by incoming segment and return. | |
| */ | |
| m_free(m); | |
| } | |
| static void | |
| tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcpiphdr *ti) | |
| { | |
| uint16_t mss; | |
| int opt, optlen; | |
| DEBUG_CALL("tcp_dooptions"); | |
| DEBUG_ARGS(" tp = %lx cnt=%i\n", (long)tp, cnt); | |
| 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; | |
| memcpy((char *) &mss, (char *) cp + 2, sizeof(mss)); | |
| NTOHS(mss); | |
| (void) tcp_mss(tp, mss); /* sets t_maxseg */ | |
| 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. | |
| */ | |
| #ifdef notdef | |
| 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; | |
| memcpy(sp, cp+1, (unsigned)(m->m_len - cnt - 1)); | |
| m->m_len--; | |
| return; | |
| } | |
| cnt -= m->m_len; | |
| m = m->m_next; /* XXX WRONG! Fix it! */ | |
| if (m == 0) | |
| break; | |
| } | |
| panic("tcp_pulloutofband"); | |
| } | |
| #endif /* notdef */ | |
| /* | |
| * Collect new round-trip time estimate | |
| * and update averages and current timeout. | |
| */ | |
| static void | |
| tcp_xmit_timer(register struct tcpcb *tp, int rtt) | |
| { | |
| register short delta; | |
| DEBUG_CALL("tcp_xmit_timer"); | |
| DEBUG_ARG("tp = %lx", (long)tp); | |
| DEBUG_ARG("rtt = %d", rtt); | |
| 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), | |
| (short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */ | |
| /* | |
| * 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(struct tcpcb *tp, u_int offer) | |
| { | |
| struct socket *so = tp->t_socket; | |
| u_int mss; | |
| DEBUG_CALL("tcp_mss"); | |
| DEBUG_ARG("tp = %lx", (long)tp); | |
| DEBUG_ARG("offer = %d", offer); | |
| mss = min(IF_MTU, IF_MRU) - sizeof(struct tcpiphdr); | |
| if (offer) | |
| mss = min(mss, offer); | |
| mss = max(mss, 32); | |
| if (mss < tp->t_maxseg || offer != 0) | |
| tp->t_maxseg = mss; | |
| tp->snd_cwnd = mss; | |
| sbreserve(&so->so_snd, TCP_SNDSPACE + ((TCP_SNDSPACE % mss) ? | |
| (mss - (TCP_SNDSPACE % mss)) : | |
| 0)); | |
| sbreserve(&so->so_rcv, TCP_RCVSPACE + ((TCP_RCVSPACE % mss) ? | |
| (mss - (TCP_RCVSPACE % mss)) : | |
| 0)); | |
| DEBUG_MISC(" returning mss = %d\n", mss); | |
| return mss; | |
| } |