diff options
Diffstat (limited to 'cpukit/libnetworking/netinet/tcp_subr.c')
| -rw-r--r-- | cpukit/libnetworking/netinet/tcp_subr.c | 632 |
1 files changed, 632 insertions, 0 deletions
diff --git a/cpukit/libnetworking/netinet/tcp_subr.c b/cpukit/libnetworking/netinet/tcp_subr.c new file mode 100644 index 0000000000..e268e32f19 --- /dev/null +++ b/cpukit/libnetworking/netinet/tcp_subr.c @@ -0,0 +1,632 @@ +/* + * 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 + * $Id$ + */ + +#include "opt_tcpdebug.h" + +#include <sys/param.h> +#include <sys/queue.h> +#include <sys/proc.h> +#include <sys/systm.h> +#include <sys/kernel.h> +#include <sys/sysctl.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> + +#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/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> +#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, ""); + +static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; +SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, + CTLFLAG_RW, &tcp_rttdflt , 0, ""); + +static int tcp_do_rfc1323 = 1; +SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, + CTLFLAG_RW, &tcp_do_rfc1323 , 0, ""); + +static int tcp_do_rfc1644 = 1; +SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, + CTLFLAG_RW, &tcp_do_rfc1644 , 0, ""); + +static void tcp_cleartaocache(void); +static void tcp_notify __P((struct inpcb *, int)); + +/* + * Target size of TCP PCB hash table. Will be rounded down to a prime + * number. + */ +#ifndef TCBHASHSIZE +#define TCBHASHSIZE 128 +#endif + +/* + * Tcp initialization + */ +void +tcp_init() +{ + + tcp_iss = random(); /* wrong, but better than a constant */ + tcp_ccgen = 1; + tcp_cleartaocache(); + LIST_INIT(&tcb); + tcbinfo.listhead = &tcb; + tcbinfo.hashbase = hashinit(TCBHASHSIZE, M_PCB, &tcbinfo.hashmask); + 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. + * + * 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) { + 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, 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; +#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. + */ +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 = tp->t_maxopd = tcp_mssdflt; + + 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; + /* + * 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; + inp->inp_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, errnum) + register struct tcpcb *tp; + int errnum; +{ + 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 (errnum == ETIMEDOUT && tp->t_softerror) + errnum = tp->t_softerror; + so->so_error = errnum; + 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; + register struct rtentry *rt; + + /* + * 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 / (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; + tcpstat.tcps_cachedrtt++; + } + 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; + tcpstat.tcps_cachedrttvar++; + } + /* + * 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) != 0) && 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; + tcpstat.tcps_cachedssthresh++; + } + } + /* 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); + 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; + soconnwakeup (so); + sorwakeup(so); + sowwakeup(so); +} + +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; +#if 1 + else if (cmd == PRC_MSGSIZE) + notify = tcp_mtudisc; +#endif + 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, errnum) + struct inpcb *inp; + int errnum; +{ + struct tcpcb *tp = intotcpcb(inp); + + if (tp) + tp->snd_cwnd = tp->t_maxseg; +} + +#if 1 +/* + * 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, errnum) + struct inpcb *inp; + int errnum; +{ + 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_rtt = 0; + tp->snd_nxt = tp->snd_una; + tcp_output(tp); + } +} +#endif + +/* + * 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(void) +{ } |