1 /* 2 * Copyright (c) 1982, 1986, 1988, 1990 Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)tcp_subr.c 7.20 (Berkeley) 12/1/90 34 */ 35 36 #include "param.h" 37 #include "systm.h" 38 #include "malloc.h" 39 #include "mbuf.h" 40 #include "socket.h" 41 #include "socketvar.h" 42 #include "protosw.h" 43 #include "errno.h" 44 45 #include "../net/route.h" 46 #include "../net/if.h" 47 48 #include "in.h" 49 #include "in_systm.h" 50 #include "ip.h" 51 #include "in_pcb.h" 52 #include "ip_var.h" 53 #include "ip_icmp.h" 54 #include "tcp.h" 55 #include "tcp_fsm.h" 56 #include "tcp_seq.h" 57 #include "tcp_timer.h" 58 #include "tcp_var.h" 59 #include "tcpip.h" 60 61 /* patchable/settable parameters for tcp */ 62 int tcp_ttl = TCP_TTL; 63 int tcp_mssdflt = TCP_MSS; 64 int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 65 66 extern struct inpcb *tcp_last_inpcb; 67 68 /* 69 * Tcp initialization 70 */ 71 tcp_init() 72 { 73 74 tcp_iss = 1; /* wrong */ 75 tcb.inp_next = tcb.inp_prev = &tcb; 76 if (max_protohdr < sizeof(struct tcpiphdr)) 77 max_protohdr = sizeof(struct tcpiphdr); 78 if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) 79 panic("tcp_init"); 80 } 81 82 /* 83 * Create template to be used to send tcp packets on a connection. 84 * Call after host entry created, allocates an mbuf and fills 85 * in a skeletal tcp/ip header, minimizing the amount of work 86 * necessary when the connection is used. 87 */ 88 struct tcpiphdr * 89 tcp_template(tp) 90 struct tcpcb *tp; 91 { 92 register struct inpcb *inp = tp->t_inpcb; 93 register struct mbuf *m; 94 register struct tcpiphdr *n; 95 96 if ((n = tp->t_template) == 0) { 97 m = m_get(M_DONTWAIT, MT_HEADER); 98 if (m == NULL) 99 return (0); 100 m->m_len = sizeof (struct tcpiphdr); 101 n = mtod(m, struct tcpiphdr *); 102 } 103 n->ti_next = n->ti_prev = 0; 104 n->ti_x1 = 0; 105 n->ti_pr = IPPROTO_TCP; 106 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 107 n->ti_src = inp->inp_laddr; 108 n->ti_dst = inp->inp_faddr; 109 n->ti_sport = inp->inp_lport; 110 n->ti_dport = inp->inp_fport; 111 n->ti_seq = 0; 112 n->ti_ack = 0; 113 n->ti_x2 = 0; 114 n->ti_off = 5; 115 n->ti_flags = 0; 116 n->ti_win = 0; 117 n->ti_sum = 0; 118 n->ti_urp = 0; 119 return (n); 120 } 121 122 /* 123 * Send a single message to the TCP at address specified by 124 * the given TCP/IP header. If m == 0, then we make a copy 125 * of the tcpiphdr at ti and send directly to the addressed host. 126 * This is used to force keep alive messages out using the TCP 127 * template for a connection tp->t_template. If flags are given 128 * then we send a message back to the TCP which originated the 129 * segment ti, and discard the mbuf containing it and any other 130 * attached mbufs. 131 * 132 * In any case the ack and sequence number of the transmitted 133 * segment are as specified by the parameters. 134 */ 135 tcp_respond(tp, ti, m, ack, seq, flags) 136 struct tcpcb *tp; 137 register struct tcpiphdr *ti; 138 register struct mbuf *m; 139 tcp_seq ack, seq; 140 int flags; 141 { 142 register int tlen; 143 int win = 0; 144 struct route *ro = 0; 145 146 if (tp) { 147 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 148 ro = &tp->t_inpcb->inp_route; 149 } 150 if (m == 0) { 151 m = m_gethdr(M_DONTWAIT, MT_HEADER); 152 if (m == NULL) 153 return; 154 #ifdef TCP_COMPAT_42 155 tlen = 1; 156 #else 157 tlen = 0; 158 #endif 159 m->m_data += max_linkhdr; 160 *mtod(m, struct tcpiphdr *) = *ti; 161 ti = mtod(m, struct tcpiphdr *); 162 flags = TH_ACK; 163 } else { 164 m_freem(m->m_next); 165 m->m_next = 0; 166 m->m_data = (caddr_t)ti; 167 m->m_len = sizeof (struct tcpiphdr); 168 tlen = 0; 169 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 170 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 171 xchg(ti->ti_dport, ti->ti_sport, u_short); 172 #undef xchg 173 } 174 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 175 tlen += sizeof (struct tcpiphdr); 176 m->m_len = tlen; 177 m->m_pkthdr.len = tlen; 178 m->m_pkthdr.rcvif = (struct ifnet *) 0; 179 ti->ti_next = ti->ti_prev = 0; 180 ti->ti_x1 = 0; 181 ti->ti_seq = htonl(seq); 182 ti->ti_ack = htonl(ack); 183 ti->ti_x2 = 0; 184 ti->ti_off = sizeof (struct tcphdr) >> 2; 185 ti->ti_flags = flags; 186 ti->ti_win = htons((u_short)win); 187 ti->ti_urp = 0; 188 ti->ti_sum = in_cksum(m, tlen); 189 ((struct ip *)ti)->ip_len = tlen; 190 ((struct ip *)ti)->ip_ttl = tcp_ttl; 191 (void) ip_output(m, (struct mbuf *)0, ro, 0); 192 } 193 194 /* 195 * Create a new TCP control block, making an 196 * empty reassembly queue and hooking it to the argument 197 * protocol control block. 198 */ 199 struct tcpcb * 200 tcp_newtcpcb(inp) 201 struct inpcb *inp; 202 { 203 struct mbuf *m = m_getclr(M_DONTWAIT, MT_PCB); 204 register struct tcpcb *tp; 205 206 if (m == NULL) 207 return ((struct tcpcb *)0); 208 tp = mtod(m, struct tcpcb *); 209 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 210 tp->t_maxseg = tcp_mssdflt; 211 212 tp->t_flags = 0; /* sends options! */ 213 tp->t_inpcb = inp; 214 /* 215 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 216 * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives 217 * reasonable initial retransmit time. 218 */ 219 tp->t_srtt = TCPTV_SRTTBASE; 220 tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << 2; 221 tp->t_rttmin = TCPTV_MIN; 222 TCPT_RANGESET(tp->t_rxtcur, 223 ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1, 224 TCPTV_MIN, TCPTV_REXMTMAX); 225 tp->snd_cwnd = TCP_MAXWIN; 226 tp->snd_ssthresh = TCP_MAXWIN; 227 inp->inp_ip.ip_ttl = tcp_ttl; 228 inp->inp_ppcb = (caddr_t)tp; 229 return (tp); 230 } 231 232 /* 233 * Drop a TCP connection, reporting 234 * the specified error. If connection is synchronized, 235 * then send a RST to peer. 236 */ 237 struct tcpcb * 238 tcp_drop(tp, errno) 239 register struct tcpcb *tp; 240 int errno; 241 { 242 struct socket *so = tp->t_inpcb->inp_socket; 243 244 if (TCPS_HAVERCVDSYN(tp->t_state)) { 245 tp->t_state = TCPS_CLOSED; 246 (void) tcp_output(tp); 247 tcpstat.tcps_drops++; 248 } else 249 tcpstat.tcps_conndrops++; 250 if (errno == ETIMEDOUT && tp->t_softerror) 251 errno = tp->t_softerror; 252 so->so_error = errno; 253 return (tcp_close(tp)); 254 } 255 256 /* 257 * Close a TCP control block: 258 * discard all space held by the tcp 259 * discard internet protocol block 260 * wake up any sleepers 261 */ 262 struct tcpcb * 263 tcp_close(tp) 264 register struct tcpcb *tp; 265 { 266 register struct tcpiphdr *t; 267 struct inpcb *inp = tp->t_inpcb; 268 struct socket *so = inp->inp_socket; 269 register struct mbuf *m; 270 #ifdef RTV_RTT 271 register struct rtentry *rt; 272 273 /* 274 * If we sent enough data to get some meaningful characteristics, 275 * save them in the routing entry. 'Enough' is arbitrarily 276 * defined as the sendpipesize (default 4K) * 16. This would 277 * give us 16 rtt samples assuming we only get one sample per 278 * window (the usual case on a long haul net). 16 samples is 279 * enough for the srtt filter to converge to within 5% of the correct 280 * value; fewer samples and we could save a very bogus rtt. 281 * 282 * Don't update the default route's characteristics and don't 283 * update anything that the user "locked". 284 */ 285 if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) && 286 (rt = inp->inp_route.ro_rt) && 287 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) { 288 register u_long i; 289 290 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { 291 i = tp->t_srtt * 292 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); 293 if (rt->rt_rmx.rmx_rtt && i) 294 /* 295 * filter this update to half the old & half 296 * the new values, converting scale. 297 * See route.h and tcp_var.h for a 298 * description of the scaling constants. 299 */ 300 rt->rt_rmx.rmx_rtt = 301 (rt->rt_rmx.rmx_rtt + i) / 2; 302 else 303 rt->rt_rmx.rmx_rtt = i; 304 } 305 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { 306 i = tp->t_rttvar * 307 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); 308 if (rt->rt_rmx.rmx_rttvar && i) 309 rt->rt_rmx.rmx_rttvar = 310 (rt->rt_rmx.rmx_rttvar + i) / 2; 311 else 312 rt->rt_rmx.rmx_rttvar = i; 313 } 314 /* 315 * update the pipelimit (ssthresh) if it has been updated 316 * already or if a pipesize was specified & the threshhold 317 * got below half the pipesize. I.e., wait for bad news 318 * before we start updating, then update on both good 319 * and bad news. 320 */ 321 if ((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && 322 (i = tp->snd_ssthresh) && rt->rt_rmx.rmx_ssthresh || 323 i < (rt->rt_rmx.rmx_sendpipe / 2)) { 324 /* 325 * convert the limit from user data bytes to 326 * packets then to packet data bytes. 327 */ 328 i = (i + tp->t_maxseg / 2) / tp->t_maxseg; 329 if (i < 2) 330 i = 2; 331 i *= (u_long)(tp->t_maxseg + sizeof (struct tcpiphdr)); 332 if (rt->rt_rmx.rmx_ssthresh) 333 rt->rt_rmx.rmx_ssthresh = 334 (rt->rt_rmx.rmx_ssthresh + i) / 2; 335 else 336 rt->rt_rmx.rmx_ssthresh = i; 337 } 338 } 339 #endif RTV_RTT 340 /* free the reassembly queue, if any */ 341 t = tp->seg_next; 342 while (t != (struct tcpiphdr *)tp) { 343 t = (struct tcpiphdr *)t->ti_next; 344 m = REASS_MBUF((struct tcpiphdr *)t->ti_prev); 345 remque(t->ti_prev); 346 m_freem(m); 347 } 348 if (tp->t_template) 349 (void) m_free(dtom(tp->t_template)); 350 (void) m_free(dtom(tp)); 351 inp->inp_ppcb = 0; 352 soisdisconnected(so); 353 /* clobber input pcb cache if we're closing the cached connection */ 354 if (inp == tcp_last_inpcb) 355 tcp_last_inpcb = &tcb; 356 in_pcbdetach(inp); 357 tcpstat.tcps_closed++; 358 return ((struct tcpcb *)0); 359 } 360 361 tcp_drain() 362 { 363 364 } 365 366 /* 367 * Notify a tcp user of an asynchronous error; 368 * store error as soft error, but wake up user 369 * (for now, won't do anything until can select for soft error). 370 */ 371 tcp_notify(inp, error) 372 register struct inpcb *inp; 373 int error; 374 { 375 376 ((struct tcpcb *)inp->inp_ppcb)->t_softerror = error; 377 wakeup((caddr_t) &inp->inp_socket->so_timeo); 378 sorwakeup(inp->inp_socket); 379 sowwakeup(inp->inp_socket); 380 } 381 382 tcp_ctlinput(cmd, sa, ip) 383 int cmd; 384 struct sockaddr *sa; 385 register struct ip *ip; 386 { 387 register struct tcphdr *th; 388 extern struct in_addr zeroin_addr; 389 extern u_char inetctlerrmap[]; 390 int (*notify)() = tcp_notify, tcp_quench(); 391 392 if (cmd == PRC_QUENCH) 393 notify = tcp_quench; 394 else if ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0) 395 return; 396 if (ip) { 397 th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2)); 398 in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport, 399 cmd, notify); 400 } else 401 in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, notify); 402 } 403 404 /* 405 * When a source quench is received, close congestion window 406 * to one segment. We will gradually open it again as we proceed. 407 */ 408 tcp_quench(inp) 409 struct inpcb *inp; 410 { 411 struct tcpcb *tp = intotcpcb(inp); 412 413 if (tp) 414 tp->snd_cwnd = tp->t_maxseg; 415 } 416