diff options
Diffstat (limited to 'sys/netinet/tcp_subr.c')
| -rw-r--r-- | sys/netinet/tcp_subr.c | 839 |
1 files changed, 839 insertions, 0 deletions
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c new file mode 100644 index 0000000..fd3e435 --- /dev/null +++ b/sys/netinet/tcp_subr.c @@ -0,0 +1,839 @@ +/* + * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 + * 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 8.2 (Berkeley) 5/24/95 + * $FreeBSD$ + */ + +#include "opt_compat.h" +#include "opt_inet6.h" +#include "opt_tcpdebug.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/callout.h> +#include <sys/kernel.h> +#include <sys/sysctl.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/proc.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/protosw.h> + +#include <vm/vm_zone.h> + +#include <net/route.h> +#include <net/if.h> + +#define _IP_VHL +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/in_pcb.h> +#include <netinet/in_var.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> +#ifdef TCPDEBUG +#include <netinet/tcp_debug.h> +#endif + +int tcp_mssdflt = TCP_MSS; +SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, + &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); + +#ifdef INET6 +int tcp_v6mssdflt = TCP6_MSS; +SYSCTL_INT(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt, + CTLFLAG_RW, &tcp_v6mssdflt , 0, ""); +#endif + +#if 0 +static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; +SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, + &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); +#endif + +static int tcp_do_rfc1323 = 1; +SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, + &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); + +static int tcp_do_rfc1644 = 0; +SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW, + &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions"); + +static int tcp_tcbhashsize = 0; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RD, + &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable"); + +SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, + &tcbinfo.ipi_count, 0, "Number of active PCBs"); + +static void tcp_cleartaocache __P((void)); +static void tcp_notify __P((struct inpcb *, int)); + +/* + * Target size of TCP PCB hash tables. Must be a power of two. + * + * Note that this can be overridden by the kernel environment + * variable net.inet.tcp.tcbhashsize + */ +#ifndef TCBHASHSIZE +#define TCBHASHSIZE 512 +#endif + +/* + * This is the actual shape of what we allocate using the zone + * allocator. Doing it this way allows us to protect both structures + * using the same generation count, and also eliminates the overhead + * of allocating tcpcbs separately. By hiding the structure here, + * we avoid changing most of the rest of the code (although it needs + * to be changed, eventually, for greater efficiency). + */ +#define ALIGNMENT 32 +#define ALIGNM1 (ALIGNMENT - 1) +struct inp_tp { + union { + struct inpcb inp; + char align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1]; + } inp_tp_u; + struct tcpcb tcb; + struct callout inp_tp_rexmt, inp_tp_persist, inp_tp_keep, inp_tp_2msl; + struct callout inp_tp_delack; +}; +#undef ALIGNMENT +#undef ALIGNM1 + +/* + * Tcp initialization + */ +void +tcp_init() +{ + int hashsize; + + tcp_iss = random(); /* wrong, but better than a constant */ + tcp_ccgen = 1; + tcp_cleartaocache(); + + tcp_delacktime = TCPTV_DELACK; + tcp_keepinit = TCPTV_KEEP_INIT; + tcp_keepidle = TCPTV_KEEP_IDLE; + tcp_keepintvl = TCPTV_KEEPINTVL; + tcp_maxpersistidle = TCPTV_KEEP_IDLE; + tcp_msl = TCPTV_MSL; + + LIST_INIT(&tcb); + tcbinfo.listhead = &tcb; + TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", TCBHASHSIZE, hashsize); + if (!powerof2(hashsize)) { + printf("WARNING: TCB hash size not a power of 2\n"); + hashsize = 512; /* safe default */ + } + tcp_tcbhashsize = hashsize; + tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); + tcbinfo.porthashbase = hashinit(hashsize, M_PCB, + &tcbinfo.porthashmask); + tcbinfo.ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets, + ZONE_INTERRUPT, 0); + + 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 *); + } + bzero(n->ti_x1, sizeof(n->ti_x1)); + 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. + * + * NOTE: If m != NULL, then ti must point to *inside* the mbuf. + */ +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; + struct route sro; + + if (tp) { + if (!(flags & TH_RST)) + win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); + ro = &tp->t_inpcb->inp_route; + } else { + ro = &sro; + bzero(ro, sizeof *ro); + } + 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, n_long); + xchg(ti->ti_dport, ti->ti_sport, n_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; + bzero(ti->ti_x1, sizeof(ti->ti_x1)); + 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; +#ifdef TCPDEBUG + if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) + tcp_trace(TA_OUTPUT, 0, tp, ti, 0); +#endif + (void) ip_output(m, NULL, ro, 0, NULL); + if (ro == &sro && ro->ro_rt) { + RTFREE(ro->ro_rt); + } +} + +/* + * Create a new TCP control block, making an + * empty reassembly queue and hooking it to the argument + * protocol control block. The `inp' parameter must have + * come from the zone allocator set up in tcp_init(). + */ +struct tcpcb * +tcp_newtcpcb(inp) + struct inpcb *inp; +{ + struct inp_tp *it; + register struct tcpcb *tp; + + it = (struct inp_tp *)inp; + tp = &it->tcb; + bzero((char *) tp, sizeof(struct tcpcb)); + tp->t_segq = NULL; + tp->t_maxseg = tp->t_maxopd = tcp_mssdflt; + + /* Set up our timeouts. */ + callout_init(tp->tt_rexmt = &it->inp_tp_rexmt); + callout_init(tp->tt_persist = &it->inp_tp_persist); + callout_init(tp->tt_keep = &it->inp_tp_keep); + callout_init(tp->tt_2msl = &it->inp_tp_2msl); + callout_init(tp->tt_delack = &it->inp_tp_delack); + + if (tcp_do_rfc1323) + tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); + if (tcp_do_rfc1644) + tp->t_flags |= TF_REQ_CC; + tp->t_inpcb = inp; /* XXX */ + /* + * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no + * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives + * reasonable initial retransmit time. + */ + tp->t_srtt = TCPTV_SRTTBASE; + tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; + tp->t_rttmin = TCPTV_MIN; + tp->t_rxtcur = TCPTV_RTOBASE; + tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; + tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; + tp->t_rcvtime = ticks; + inp->inp_ip_ttl = ip_defttl; + inp->inp_ppcb = (caddr_t)tp; + return (tp); /* XXX */ +} + +/* + * 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 mbuf *q; + register struct mbuf *nq; + struct inpcb *inp = tp->t_inpcb; + struct socket *so = inp->inp_socket; + register struct rtentry *rt; + int dosavessthresh; + + /* + * Make sure that all of our timers are stopped before we + * delete the PCB. + */ + callout_stop(tp->tt_rexmt); + callout_stop(tp->tt_persist); + callout_stop(tp->tt_keep); + callout_stop(tp->tt_2msl); + callout_stop(tp->tt_delack); + + /* + * If we got enough samples through the srtt filter, + * save the rtt and rttvar in the routing entry. + * 'Enough' is arbitrarily defined as the 16 samples. + * 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 (tp->t_rttupdated >= 16 && + (rt = inp->inp_route.ro_rt) && + ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) { + register u_long i = 0; + + if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { + i = tp->t_srtt * + (RTM_RTTUNIT / (hz * 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; + tcpstat.tcps_cachedrtt++; + } + if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { + i = tp->t_rttvar * + (RTM_RTTUNIT / (hz * 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; + tcpstat.tcps_cachedrttvar++; + } + /* + * The old comment here said: + * 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. + * + * But we want to save the ssthresh even if no pipesize is + * specified explicitly in the route, because such + * connections still have an implicit pipesize specified + * by the global tcp_sendspace. In the absence of a reliable + * way to calculate the pipesize, it will have to do. + */ + i = tp->snd_ssthresh; + if (rt->rt_rmx.rmx_sendpipe != 0) + dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2); + else + dosavessthresh = (i < so->so_snd.sb_hiwat / 2); + if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && + i != 0 && rt->rt_rmx.rmx_ssthresh != 0) + || dosavessthresh) { + /* + * 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; + tcpstat.tcps_cachedssthresh++; + } + } + /* free the reassembly queue, if any */ + for (q = tp->t_segq; q; q = nq) { + nq = q->m_nextpkt; + tp->t_segq = nq; + m_freem(q); + } + if (tp->t_template) + (void) m_free(dtom(tp->t_template)); + inp->inp_ppcb = NULL; + soisdisconnected(so); + 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). + */ +static 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); +} + +static int +tcp_pcblist SYSCTL_HANDLER_ARGS +{ + int error, i, n, s; + struct inpcb *inp, **inp_list; + inp_gen_t gencnt; + struct xinpgen xig; + + /* + * The process of preparing the TCB list is too time-consuming and + * resource-intensive to repeat twice on every request. + */ + if (req->oldptr == 0) { + n = tcbinfo.ipi_count; + req->oldidx = 2 * (sizeof xig) + + (n + n/8) * sizeof(struct xtcpcb); + return 0; + } + + if (req->newptr != 0) + return EPERM; + + /* + * OK, now we're committed to doing something. + */ + s = splnet(); + gencnt = tcbinfo.ipi_gencnt; + n = tcbinfo.ipi_count; + splx(s); + + xig.xig_len = sizeof xig; + xig.xig_count = n; + xig.xig_gen = gencnt; + xig.xig_sogen = so_gencnt; + error = SYSCTL_OUT(req, &xig, sizeof xig); + if (error) + return error; + + inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); + if (inp_list == 0) + return ENOMEM; + + s = splnet(); + for (inp = tcbinfo.listhead->lh_first, i = 0; inp && i < n; + inp = inp->inp_list.le_next) { + if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->p, inp)) + inp_list[i++] = inp; + } + splx(s); + n = i; + + error = 0; + for (i = 0; i < n; i++) { + inp = inp_list[i]; + if (inp->inp_gencnt <= gencnt) { + struct xtcpcb xt; + caddr_t inp_ppcb; + xt.xt_len = sizeof xt; + /* XXX should avoid extra copy */ + bcopy(inp, &xt.xt_inp, sizeof *inp); + inp_ppcb = inp->inp_ppcb; + if (inp_ppcb != NULL) + bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); + else + bzero((char *) &xt.xt_tp, sizeof xt.xt_tp); + if (inp->inp_socket) + sotoxsocket(inp->inp_socket, &xt.xt_socket); + error = SYSCTL_OUT(req, &xt, sizeof xt); + } + } + if (!error) { + /* + * Give the user an updated idea of our state. + * If the generation differs from what we told + * her before, she knows that something happened + * while we were processing this request, and it + * might be necessary to retry. + */ + s = splnet(); + xig.xig_gen = tcbinfo.ipi_gencnt; + xig.xig_sogen = so_gencnt; + xig.xig_count = tcbinfo.ipi_count; + splx(s); + error = SYSCTL_OUT(req, &xig, sizeof xig); + } + free(inp_list, M_TEMP); + return error; +} + +SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, + tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); + +static int +tcp_getcred SYSCTL_HANDLER_ARGS +{ + struct sockaddr_in addrs[2]; + struct inpcb *inp; + int error, s; + + error = suser(req->p); + if (error) + return (error); + error = SYSCTL_IN(req, addrs, sizeof(addrs)); + if (error) + return (error); + s = splnet(); + inp = in_pcblookup_hash(&tcbinfo, addrs[1].sin_addr, addrs[1].sin_port, + addrs[0].sin_addr, addrs[0].sin_port, 0, NULL); + if (inp == NULL || inp->inp_socket == NULL) { + error = ENOENT; + goto out; + } + error = SYSCTL_OUT(req, inp->inp_socket->so_cred, sizeof(struct ucred)); +out: + splx(s); + return (error); +} + +SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred, CTLTYPE_OPAQUE|CTLFLAG_RW, + 0, 0, tcp_getcred, "S,ucred", "Get the ucred of a TCP connection"); + +void +tcp_ctlinput(cmd, sa, vip) + int cmd; + struct sockaddr *sa; + void *vip; +{ + register struct ip *ip = vip; + register struct tcphdr *th; + void (*notify) __P((struct inpcb *, int)) = tcp_notify; + + if (cmd == PRC_QUENCH) + notify = tcp_quench; + else if (cmd == PRC_MSGSIZE) + notify = tcp_mtudisc; + else if (!PRC_IS_REDIRECT(cmd) && + ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0)) + return; + if (ip) { + th = (struct tcphdr *)((caddr_t)ip + + (IP_VHL_HL(ip->ip_vhl) << 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; +} + +/* + * When `need fragmentation' ICMP is received, update our idea of the MSS + * based on the new value in the route. Also nudge TCP to send something, + * since we know the packet we just sent was dropped. + * This duplicates some code in the tcp_mss() function in tcp_input.c. + */ +void +tcp_mtudisc(inp, errno) + struct inpcb *inp; + int errno; +{ + struct tcpcb *tp = intotcpcb(inp); + struct rtentry *rt; + struct rmxp_tao *taop; + struct socket *so = inp->inp_socket; + int offered; + int mss; + + if (tp) { + rt = tcp_rtlookup(inp); + if (!rt || !rt->rt_rmx.rmx_mtu) { + tp->t_maxopd = tp->t_maxseg = tcp_mssdflt; + return; + } + taop = rmx_taop(rt->rt_rmx); + offered = taop->tao_mssopt; + mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr); + if (offered) + mss = min(mss, offered); + /* + * XXX - The above conditional probably violates the TCP + * spec. The problem is that, since we don't know the + * other end's MSS, we are supposed to use a conservative + * default. But, if we do that, then MTU discovery will + * never actually take place, because the conservative + * default is much less than the MTUs typically seen + * on the Internet today. For the moment, we'll sweep + * this under the carpet. + * + * The conservative default might not actually be a problem + * if the only case this occurs is when sending an initial + * SYN with options and data to a host we've never talked + * to before. Then, they will reply with an MSS value which + * will get recorded and the new parameters should get + * recomputed. For Further Study. + */ + if (tp->t_maxopd <= mss) + return; + tp->t_maxopd = mss; + + if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && + (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) + mss -= TCPOLEN_TSTAMP_APPA; + if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && + (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) + mss -= TCPOLEN_CC_APPA; +#if (MCLBYTES & (MCLBYTES - 1)) == 0 + if (mss > MCLBYTES) + mss &= ~(MCLBYTES-1); +#else + if (mss > MCLBYTES) + mss = mss / MCLBYTES * MCLBYTES; +#endif + if (so->so_snd.sb_hiwat < mss) + mss = so->so_snd.sb_hiwat; + + tp->t_maxseg = mss; + + tcpstat.tcps_mturesent++; + tp->t_rtttime = 0; + tp->snd_nxt = tp->snd_una; + tcp_output(tp); + } +} + +/* + * Look-up the routing entry to the peer of this inpcb. If no route + * is found and it cannot be allocated the return NULL. This routine + * is called by TCP routines that access the rmx structure and by tcp_mss + * to get the interface MTU. + */ +struct rtentry * +tcp_rtlookup(inp) + struct inpcb *inp; +{ + struct route *ro; + struct rtentry *rt; + + ro = &inp->inp_route; + rt = ro->ro_rt; + if (rt == NULL || !(rt->rt_flags & RTF_UP)) { + /* 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); + rt = ro->ro_rt; + } + } + return rt; +} + +/* + * Return a pointer to the cached information about the remote host. + * The cached information is stored in the protocol specific part of + * the route metrics. + */ +struct rmxp_tao * +tcp_gettaocache(inp) + struct inpcb *inp; +{ + struct rtentry *rt = tcp_rtlookup(inp); + + /* Make sure this is a host route and is up. */ + if (rt == NULL || + (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST)) + return NULL; + + return rmx_taop(rt->rt_rmx); +} + +/* + * Clear all the TAO cache entries, called from tcp_init. + * + * XXX + * This routine is just an empty one, because we assume that the routing + * routing tables are initialized at the same time when TCP, so there is + * nothing in the cache left over. + */ +static void +tcp_cleartaocache() +{ +} |
