tcp_timewait.c revision 3311
1150043Smaxim/* 2150043Smaxim * Copyright (c) 1982, 1986, 1988, 1990, 1993 3150043Smaxim * The Regents of the University of California. All rights reserved. 4150043Smaxim * 5150043Smaxim * Redistribution and use in source and binary forms, with or without 6150043Smaxim * modification, are permitted provided that the following conditions 7150043Smaxim * are met: 8150043Smaxim * 1. Redistributions of source code must retain the above copyright 9150043Smaxim * notice, this list of conditions and the following disclaimer. 10150043Smaxim * 2. Redistributions in binary form must reproduce the above copyright 11150043Smaxim * notice, this list of conditions and the following disclaimer in the 12150043Smaxim * documentation and/or other materials provided with the distribution. 13150043Smaxim * 3. All advertising materials mentioning features or use of this software 14150043Smaxim * must display the following acknowledgement: 15150043Smaxim * This product includes software developed by the University of 16150043Smaxim * California, Berkeley and its contributors. 17150043Smaxim * 4. Neither the name of the University nor the names of its contributors 18150043Smaxim * may be used to endorse or promote products derived from this software 19150043Smaxim * without specific prior written permission. 20150043Smaxim * 21150043Smaxim * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22150043Smaxim * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23150043Smaxim * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24150043Smaxim * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25150043Smaxim * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26150043Smaxim * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27150043Smaxim * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28150043Smaxim * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29150043Smaxim * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30150043Smaxim * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31150043Smaxim * SUCH DAMAGE. 32150043Smaxim * 33150043Smaxim * @(#)tcp_subr.c 8.1 (Berkeley) 6/10/93 34150043Smaxim * $Id: tcp_subr.c,v 1.3 1994/08/02 07:49:08 davidg Exp $ 35150043Smaxim */ 36150043Smaxim 37150043Smaxim#include <sys/param.h> 38150043Smaxim#include <sys/proc.h> 39150043Smaxim#include <sys/systm.h> 40150043Smaxim#include <sys/malloc.h> 41150043Smaxim#include <sys/mbuf.h> 42150043Smaxim#include <sys/socket.h> 43150043Smaxim#include <sys/socketvar.h> 44150043Smaxim#include <sys/protosw.h> 45150043Smaxim#include <sys/errno.h> 46150043Smaxim 47150043Smaxim#include <net/route.h> 48150043Smaxim#include <net/if.h> 49150043Smaxim 50150043Smaxim#include <netinet/in.h> 51150043Smaxim#include <netinet/in_systm.h> 52150043Smaxim#include <netinet/ip.h> 53150043Smaxim#include <netinet/in_pcb.h> 54150043Smaxim#include <netinet/ip_var.h> 55150043Smaxim#include <netinet/ip_icmp.h> 56150043Smaxim#include <netinet/tcp.h> 57150043Smaxim#include <netinet/tcp_fsm.h> 58150043Smaxim#include <netinet/tcp_seq.h> 59150043Smaxim#include <netinet/tcp_timer.h> 60150043Smaxim#include <netinet/tcp_var.h> 61150043Smaxim#include <netinet/tcpip.h> 62150043Smaxim 63150043Smaxim/* patchable/settable parameters for tcp */ 64150043Smaximint tcp_mssdflt = TCP_MSS; 65150043Smaximint tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 66150043Smaximint tcp_do_rfc1323 = 1; 67150043Smaxim 68150043Smaximextern struct inpcb *tcp_last_inpcb; 69150043Smaxim 70150043Smaxim/* 71150043Smaxim * Tcp initialization 72150043Smaxim */ 73150043Smaximvoid 74150043Smaximtcp_init() 75150043Smaxim{ 76150043Smaxim 77150043Smaxim tcp_iss = 1; /* wrong */ 78150043Smaxim tcb.inp_next = tcb.inp_prev = &tcb; 79150043Smaxim if (max_protohdr < sizeof(struct tcpiphdr)) 80150043Smaxim max_protohdr = sizeof(struct tcpiphdr); 81150043Smaxim if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) 82150043Smaxim panic("tcp_init"); 83150043Smaxim} 84150043Smaxim 85150043Smaxim/* 86150043Smaxim * Create template to be used to send tcp packets on a connection. 87150043Smaxim * Call after host entry created, allocates an mbuf and fills 88150043Smaxim * in a skeletal tcp/ip header, minimizing the amount of work 89150043Smaxim * necessary when the connection is used. 90150043Smaxim */ 91150043Smaximstruct tcpiphdr * 92150043Smaximtcp_template(tp) 93150043Smaxim struct tcpcb *tp; 94150043Smaxim{ 95150043Smaxim register struct inpcb *inp = tp->t_inpcb; 96150043Smaxim register struct mbuf *m; 97150043Smaxim register struct tcpiphdr *n; 98150043Smaxim 99150043Smaxim if ((n = tp->t_template) == 0) { 100150043Smaxim m = m_get(M_DONTWAIT, MT_HEADER); 101150043Smaxim if (m == NULL) 102150043Smaxim return (0); 103150043Smaxim m->m_len = sizeof (struct tcpiphdr); 104150043Smaxim n = mtod(m, struct tcpiphdr *); 105150043Smaxim } 106150043Smaxim n->ti_next = n->ti_prev = 0; 107150043Smaxim n->ti_x1 = 0; 108150043Smaxim n->ti_pr = IPPROTO_TCP; 109150043Smaxim n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 110150043Smaxim n->ti_src = inp->inp_laddr; 111150043Smaxim n->ti_dst = inp->inp_faddr; 112150043Smaxim n->ti_sport = inp->inp_lport; 113150043Smaxim n->ti_dport = inp->inp_fport; 114150043Smaxim n->ti_seq = 0; 115150043Smaxim n->ti_ack = 0; 116 n->ti_x2 = 0; 117 n->ti_off = 5; 118 n->ti_flags = 0; 119 n->ti_win = 0; 120 n->ti_sum = 0; 121 n->ti_urp = 0; 122 return (n); 123} 124 125/* 126 * Send a single message to the TCP at address specified by 127 * the given TCP/IP header. If m == 0, then we make a copy 128 * of the tcpiphdr at ti and send directly to the addressed host. 129 * This is used to force keep alive messages out using the TCP 130 * template for a connection tp->t_template. If flags are given 131 * then we send a message back to the TCP which originated the 132 * segment ti, and discard the mbuf containing it and any other 133 * attached mbufs. 134 * 135 * In any case the ack and sequence number of the transmitted 136 * segment are as specified by the parameters. 137 */ 138void 139tcp_respond(tp, ti, m, ack, seq, flags) 140 struct tcpcb *tp; 141 register struct tcpiphdr *ti; 142 register struct mbuf *m; 143 tcp_seq ack, seq; 144 int flags; 145{ 146 register int tlen; 147 int win = 0; 148 struct route *ro = 0; 149 150 if (tp) { 151 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 152 ro = &tp->t_inpcb->inp_route; 153 } 154 if (m == 0) { 155 m = m_gethdr(M_DONTWAIT, MT_HEADER); 156 if (m == NULL) 157 return; 158#ifdef TCP_COMPAT_42 159 tlen = 1; 160#else 161 tlen = 0; 162#endif 163 m->m_data += max_linkhdr; 164 *mtod(m, struct tcpiphdr *) = *ti; 165 ti = mtod(m, struct tcpiphdr *); 166 flags = TH_ACK; 167 } else { 168 m_freem(m->m_next); 169 m->m_next = 0; 170 m->m_data = (caddr_t)ti; 171 m->m_len = sizeof (struct tcpiphdr); 172 tlen = 0; 173#define xchg(a,b,type) { type t; t=a; a=b; b=t; } 174 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 175 xchg(ti->ti_dport, ti->ti_sport, u_short); 176#undef xchg 177 } 178 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 179 tlen += sizeof (struct tcpiphdr); 180 m->m_len = tlen; 181 m->m_pkthdr.len = tlen; 182 m->m_pkthdr.rcvif = (struct ifnet *) 0; 183 ti->ti_next = ti->ti_prev = 0; 184 ti->ti_x1 = 0; 185 ti->ti_seq = htonl(seq); 186 ti->ti_ack = htonl(ack); 187 ti->ti_x2 = 0; 188 ti->ti_off = sizeof (struct tcphdr) >> 2; 189 ti->ti_flags = flags; 190 if (tp) 191 ti->ti_win = htons((u_short) (win >> tp->rcv_scale)); 192 else 193 ti->ti_win = htons((u_short)win); 194 ti->ti_urp = 0; 195 ti->ti_sum = 0; 196 ti->ti_sum = in_cksum(m, tlen); 197 ((struct ip *)ti)->ip_len = tlen; 198 ((struct ip *)ti)->ip_ttl = ip_defttl; 199 (void) ip_output(m, NULL, ro, 0, NULL); 200} 201 202/* 203 * Create a new TCP control block, making an 204 * empty reassembly queue and hooking it to the argument 205 * protocol control block. 206 */ 207struct tcpcb * 208tcp_newtcpcb(inp) 209 struct inpcb *inp; 210{ 211 register struct tcpcb *tp; 212 213 tp = malloc(sizeof(*tp), M_PCB, M_NOWAIT); 214 if (tp == NULL) 215 return ((struct tcpcb *)0); 216 bzero((char *) tp, sizeof(struct tcpcb)); 217 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 218 tp->t_maxseg = tcp_mssdflt; 219 220 tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 221 tp->t_inpcb = inp; 222 /* 223 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 224 * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives 225 * reasonable initial retransmit time. 226 */ 227 tp->t_srtt = TCPTV_SRTTBASE; 228 tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << 2; 229 tp->t_rttmin = TCPTV_MIN; 230 TCPT_RANGESET(tp->t_rxtcur, 231 ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1, 232 TCPTV_MIN, TCPTV_REXMTMAX); 233 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 234 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 235 inp->inp_ip.ip_ttl = ip_defttl; 236 inp->inp_ppcb = (caddr_t)tp; 237 return (tp); 238} 239 240/* 241 * Drop a TCP connection, reporting 242 * the specified error. If connection is synchronized, 243 * then send a RST to peer. 244 */ 245struct tcpcb * 246tcp_drop(tp, errno) 247 register struct tcpcb *tp; 248 int errno; 249{ 250 struct socket *so = tp->t_inpcb->inp_socket; 251 252 if (TCPS_HAVERCVDSYN(tp->t_state)) { 253 tp->t_state = TCPS_CLOSED; 254 (void) tcp_output(tp); 255 tcpstat.tcps_drops++; 256 } else 257 tcpstat.tcps_conndrops++; 258 if (errno == ETIMEDOUT && tp->t_softerror) 259 errno = tp->t_softerror; 260 so->so_error = errno; 261 return (tcp_close(tp)); 262} 263 264/* 265 * Close a TCP control block: 266 * discard all space held by the tcp 267 * discard internet protocol block 268 * wake up any sleepers 269 */ 270struct tcpcb * 271tcp_close(tp) 272 register struct tcpcb *tp; 273{ 274 register struct tcpiphdr *t; 275 struct inpcb *inp = tp->t_inpcb; 276 struct socket *so = inp->inp_socket; 277 register struct mbuf *m; 278#ifdef RTV_RTT 279 register struct rtentry *rt; 280 281 /* 282 * If we sent enough data to get some meaningful characteristics, 283 * save them in the routing entry. 'Enough' is arbitrarily 284 * defined as the sendpipesize (default 4K) * 16. This would 285 * give us 16 rtt samples assuming we only get one sample per 286 * window (the usual case on a long haul net). 16 samples is 287 * enough for the srtt filter to converge to within 5% of the correct 288 * value; fewer samples and we could save a very bogus rtt. 289 * 290 * Don't update the default route's characteristics and don't 291 * update anything that the user "locked". 292 */ 293 if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) && 294 (rt = inp->inp_route.ro_rt) && 295 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) { 296 register u_long i = 0; 297 298 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { 299 i = tp->t_srtt * 300 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); 301 if (rt->rt_rmx.rmx_rtt && i) 302 /* 303 * filter this update to half the old & half 304 * the new values, converting scale. 305 * See route.h and tcp_var.h for a 306 * description of the scaling constants. 307 */ 308 rt->rt_rmx.rmx_rtt = 309 (rt->rt_rmx.rmx_rtt + i) / 2; 310 else 311 rt->rt_rmx.rmx_rtt = i; 312 } 313 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { 314 i = tp->t_rttvar * 315 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); 316 if (rt->rt_rmx.rmx_rttvar && i) 317 rt->rt_rmx.rmx_rttvar = 318 (rt->rt_rmx.rmx_rttvar + i) / 2; 319 else 320 rt->rt_rmx.rmx_rttvar = i; 321 } 322 /* 323 * update the pipelimit (ssthresh) if it has been updated 324 * already or if a pipesize was specified & the threshhold 325 * got below half the pipesize. I.e., wait for bad news 326 * before we start updating, then update on both good 327 * and bad news. 328 */ 329 if ((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && 330 ((i = tp->snd_ssthresh)) && rt->rt_rmx.rmx_ssthresh || 331 i < (rt->rt_rmx.rmx_sendpipe / 2)) { 332 /* 333 * convert the limit from user data bytes to 334 * packets then to packet data bytes. 335 */ 336 i = (i + tp->t_maxseg / 2) / tp->t_maxseg; 337 if (i < 2) 338 i = 2; 339 i *= (u_long)(tp->t_maxseg + sizeof (struct tcpiphdr)); 340 if (rt->rt_rmx.rmx_ssthresh) 341 rt->rt_rmx.rmx_ssthresh = 342 (rt->rt_rmx.rmx_ssthresh + i) / 2; 343 else 344 rt->rt_rmx.rmx_ssthresh = i; 345 } 346 } 347#endif /* RTV_RTT */ 348 /* free the reassembly queue, if any */ 349 t = tp->seg_next; 350 while (t != (struct tcpiphdr *)tp) { 351 t = (struct tcpiphdr *)t->ti_next; 352 m = REASS_MBUF((struct tcpiphdr *)t->ti_prev); 353 remque(t->ti_prev); 354 m_freem(m); 355 } 356 if (tp->t_template) 357 (void) m_free(dtom(tp->t_template)); 358 free(tp, M_PCB); 359 inp->inp_ppcb = 0; 360 soisdisconnected(so); 361 /* clobber input pcb cache if we're closing the cached connection */ 362 if (inp == tcp_last_inpcb) 363 tcp_last_inpcb = &tcb; 364 in_pcbdetach(inp); 365 tcpstat.tcps_closed++; 366 return ((struct tcpcb *)0); 367} 368 369void 370tcp_drain() 371{ 372 373} 374 375/* 376 * Notify a tcp user of an asynchronous error; 377 * store error as soft error, but wake up user 378 * (for now, won't do anything until can select for soft error). 379 */ 380void 381tcp_notify(inp, error) 382 struct inpcb *inp; 383 int error; 384{ 385 register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 386 register struct socket *so = inp->inp_socket; 387 388 /* 389 * Ignore some errors if we are hooked up. 390 * If connection hasn't completed, has retransmitted several times, 391 * and receives a second error, give up now. This is better 392 * than waiting a long time to establish a connection that 393 * can never complete. 394 */ 395 if (tp->t_state == TCPS_ESTABLISHED && 396 (error == EHOSTUNREACH || error == ENETUNREACH || 397 error == EHOSTDOWN)) { 398 return; 399 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 400 tp->t_softerror) 401 so->so_error = error; 402 else 403 tp->t_softerror = error; 404 wakeup((caddr_t) &so->so_timeo); 405 sorwakeup(so); 406 sowwakeup(so); 407} 408 409void 410tcp_ctlinput(cmd, sa, ip) 411 int cmd; 412 struct sockaddr *sa; 413 register struct ip *ip; 414{ 415 register struct tcphdr *th; 416 extern struct in_addr zeroin_addr; 417 extern u_char inetctlerrmap[]; 418 void (*notify) __P((struct inpcb *, int)) = tcp_notify; 419 420 if (cmd == PRC_QUENCH) 421 notify = tcp_quench; 422 else if (!PRC_IS_REDIRECT(cmd) && 423 ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0)) 424 return; 425 if (ip) { 426 th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2)); 427 in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport, 428 cmd, notify); 429 } else 430 in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, notify); 431} 432 433/* 434 * When a source quench is received, close congestion window 435 * to one segment. We will gradually open it again as we proceed. 436 */ 437void 438tcp_quench(inp, errno) 439 struct inpcb *inp; 440 int errno; 441{ 442 struct tcpcb *tp = intotcpcb(inp); 443 444 if (tp) 445 tp->snd_cwnd = tp->t_maxseg; 446} 447