1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are permitted 6 * provided that the above copyright notice and this paragraph are 7 * duplicated in all such forms and that any documentation, 8 * advertising materials, and other materials related to such 9 * distribution and use acknowledge that the software was developed 10 * by the University of California, Berkeley. The name of the 11 * University may not be used to endorse or promote products derived 12 * from this software without specific prior written permission. 13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 15 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 16 * 17 * @(#)tcp_subr.c 7.13.1.2 (Berkeley) 02/15/89 18 */ 19 20 #include "param.h" 21 #include "systm.h" 22 #include "mbuf.h" 23 #include "socket.h" 24 #include "socketvar.h" 25 #include "protosw.h" 26 #include "errno.h" 27 28 #include "../net/route.h" 29 #include "../net/if.h" 30 31 #include "in.h" 32 #include "in_pcb.h" 33 #include "in_systm.h" 34 #include "ip.h" 35 #include "ip_var.h" 36 #include "ip_icmp.h" 37 #include "tcp.h" 38 #include "tcp_fsm.h" 39 #include "tcp_seq.h" 40 #include "tcp_timer.h" 41 #include "tcp_var.h" 42 #include "tcpip.h" 43 44 int tcp_ttl = TCP_TTL; 45 46 /* 47 * Tcp initialization 48 */ 49 tcp_init() 50 { 51 52 tcp_iss = 1; /* wrong */ 53 tcb.inp_next = tcb.inp_prev = &tcb; 54 } 55 56 /* 57 * Create template to be used to send tcp packets on a connection. 58 * Call after host entry created, allocates an mbuf and fills 59 * in a skeletal tcp/ip header, minimizing the amount of work 60 * necessary when the connection is used. 61 */ 62 struct tcpiphdr * 63 tcp_template(tp) 64 struct tcpcb *tp; 65 { 66 register struct inpcb *inp = tp->t_inpcb; 67 register struct mbuf *m; 68 register struct tcpiphdr *n; 69 70 if ((n = tp->t_template) == 0) { 71 m = m_get(M_DONTWAIT, MT_HEADER); 72 if (m == NULL) 73 return (0); 74 m->m_off = MMAXOFF - sizeof (struct tcpiphdr); 75 m->m_len = sizeof (struct tcpiphdr); 76 n = mtod(m, struct tcpiphdr *); 77 } 78 n->ti_next = n->ti_prev = 0; 79 n->ti_x1 = 0; 80 n->ti_pr = IPPROTO_TCP; 81 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 82 n->ti_src = inp->inp_laddr; 83 n->ti_dst = inp->inp_faddr; 84 n->ti_sport = inp->inp_lport; 85 n->ti_dport = inp->inp_fport; 86 n->ti_seq = 0; 87 n->ti_ack = 0; 88 n->ti_x2 = 0; 89 n->ti_off = 5; 90 n->ti_flags = 0; 91 n->ti_win = 0; 92 n->ti_sum = 0; 93 n->ti_urp = 0; 94 return (n); 95 } 96 97 /* 98 * Send a single message to the TCP at address specified by 99 * the given TCP/IP header. If flags==0, then we make a copy 100 * of the tcpiphdr at ti and send directly to the addressed host. 101 * This is used to force keep alive messages out using the TCP 102 * template for a connection tp->t_template. If flags are given 103 * then we send a message back to the TCP which originated the 104 * segment ti, and discard the mbuf containing it and any other 105 * attached mbufs. 106 * 107 * In any case the ack and sequence number of the transmitted 108 * segment are as specified by the parameters. 109 */ 110 tcp_respond(tp, ti, ack, seq, flags) 111 struct tcpcb *tp; 112 register struct tcpiphdr *ti; 113 tcp_seq ack, seq; 114 int flags; 115 { 116 register struct mbuf *m; 117 int win = 0, tlen; 118 struct route *ro = 0; 119 120 if (tp) { 121 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 122 ro = &tp->t_inpcb->inp_route; 123 } 124 if (flags == 0) { 125 m = m_get(M_DONTWAIT, MT_HEADER); 126 if (m == NULL) 127 return; 128 #ifdef TCP_COMPAT_42 129 tlen = 1; 130 #else 131 tlen = 0; 132 #endif 133 m->m_len = sizeof (struct tcpiphdr) + tlen; 134 *mtod(m, struct tcpiphdr *) = *ti; 135 ti = mtod(m, struct tcpiphdr *); 136 flags = TH_ACK; 137 } else { 138 m = dtom(ti); 139 m_freem(m->m_next); 140 m->m_next = 0; 141 m->m_off = (int)ti - (int)m; 142 tlen = 0; 143 m->m_len = sizeof (struct tcpiphdr); 144 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 145 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 146 xchg(ti->ti_dport, ti->ti_sport, u_short); 147 #undef xchg 148 } 149 ti->ti_next = ti->ti_prev = 0; 150 ti->ti_x1 = 0; 151 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 152 ti->ti_seq = htonl(seq); 153 ti->ti_ack = htonl(ack); 154 ti->ti_x2 = 0; 155 ti->ti_off = sizeof (struct tcphdr) >> 2; 156 ti->ti_flags = flags; 157 ti->ti_win = htons((u_short)win); 158 ti->ti_urp = 0; 159 ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + tlen); 160 ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + tlen; 161 ((struct ip *)ti)->ip_ttl = tcp_ttl; 162 (void) ip_output(m, (struct mbuf *)0, ro, 0); 163 } 164 165 /* 166 * Create a new TCP control block, making an 167 * empty reassembly queue and hooking it to the argument 168 * protocol control block. 169 */ 170 struct tcpcb * 171 tcp_newtcpcb(inp) 172 struct inpcb *inp; 173 { 174 struct mbuf *m = m_getclr(M_DONTWAIT, MT_PCB); 175 register struct tcpcb *tp; 176 177 if (m == NULL) 178 return ((struct tcpcb *)0); 179 tp = mtod(m, struct tcpcb *); 180 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 181 tp->t_maxseg = TCP_MSS; 182 tp->t_flags = 0; /* sends options! */ 183 tp->t_inpcb = inp; 184 /* 185 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 186 * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives 187 * reasonable initial retransmit time. 188 */ 189 tp->t_srtt = TCPTV_SRTTBASE; 190 tp->t_rttvar = TCPTV_SRTTDFLT << 2; 191 TCPT_RANGESET(tp->t_rxtcur, 192 ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1, 193 TCPTV_MIN, TCPTV_REXMTMAX); 194 tp->snd_cwnd = sbspace(&inp->inp_socket->so_snd); 195 tp->snd_ssthresh = 65535; /* XXX */ 196 inp->inp_ppcb = (caddr_t)tp; 197 return (tp); 198 } 199 200 /* 201 * Drop a TCP connection, reporting 202 * the specified error. If connection is synchronized, 203 * then send a RST to peer. 204 */ 205 struct tcpcb * 206 tcp_drop(tp, errno) 207 register struct tcpcb *tp; 208 int errno; 209 { 210 struct socket *so = tp->t_inpcb->inp_socket; 211 212 if (TCPS_HAVERCVDSYN(tp->t_state)) { 213 tp->t_state = TCPS_CLOSED; 214 (void) tcp_output(tp); 215 tcpstat.tcps_drops++; 216 } else 217 tcpstat.tcps_conndrops++; 218 so->so_error = errno; 219 return (tcp_close(tp)); 220 } 221 222 /* 223 * Close a TCP control block: 224 * discard all space held by the tcp 225 * discard internet protocol block 226 * wake up any sleepers 227 */ 228 struct tcpcb * 229 tcp_close(tp) 230 register struct tcpcb *tp; 231 { 232 register struct tcpiphdr *t; 233 struct inpcb *inp = tp->t_inpcb; 234 struct socket *so = inp->inp_socket; 235 register struct mbuf *m; 236 237 t = tp->seg_next; 238 while (t != (struct tcpiphdr *)tp) { 239 t = (struct tcpiphdr *)t->ti_next; 240 m = dtom(t->ti_prev); 241 remque(t->ti_prev); 242 m_freem(m); 243 } 244 if (tp->t_template) 245 (void) m_free(dtom(tp->t_template)); 246 (void) m_free(dtom(tp)); 247 inp->inp_ppcb = 0; 248 soisdisconnected(so); 249 in_pcbdetach(inp); 250 tcpstat.tcps_closed++; 251 return ((struct tcpcb *)0); 252 } 253 254 tcp_drain() 255 { 256 257 } 258 259 /* 260 * Notify a tcp user of an asynchronous error; 261 * just wake up so that he can collect error status. 262 */ 263 tcp_notify(inp) 264 register struct inpcb *inp; 265 { 266 267 wakeup((caddr_t) &inp->inp_socket->so_timeo); 268 sorwakeup(inp->inp_socket); 269 sowwakeup(inp->inp_socket); 270 } 271 tcp_ctlinput(cmd, sa) 272 int cmd; 273 struct sockaddr *sa; 274 { 275 extern u_char inetctlerrmap[]; 276 struct sockaddr_in *sin; 277 int tcp_quench(), in_rtchange(); 278 279 if ((unsigned)cmd > PRC_NCMDS) 280 return; 281 if (sa->sa_family != AF_INET && sa->sa_family != AF_IMPLINK) 282 return; 283 sin = (struct sockaddr_in *)sa; 284 if (sin->sin_addr.s_addr == INADDR_ANY) 285 return; 286 287 switch (cmd) { 288 289 case PRC_QUENCH: 290 in_pcbnotify(&tcb, &sin->sin_addr, 0, tcp_quench); 291 break; 292 293 case PRC_ROUTEDEAD: 294 case PRC_REDIRECT_NET: 295 case PRC_REDIRECT_HOST: 296 case PRC_REDIRECT_TOSNET: 297 case PRC_REDIRECT_TOSHOST: 298 #if BSD>=43 299 in_pcbnotify(&tcb, &sin->sin_addr, 0, in_rtchange); 300 #endif 301 break; 302 303 default: 304 if (inetctlerrmap[cmd] == 0) 305 return; /* XXX */ 306 in_pcbnotify(&tcb, &sin->sin_addr, (int)inetctlerrmap[cmd], 307 tcp_notify); 308 } 309 } 310 311 #if BSD<43 312 /* XXX fake routine */ 313 tcp_abort(inp) 314 struct inpcb *inp; 315 { 316 return; 317 } 318 #endif 319 320 /* 321 * When a source quench is received, close congestion window 322 * to one segment. We will gradually open it again as we proceed. 323 */ 324 tcp_quench(inp) 325 struct inpcb *inp; 326 { 327 struct tcpcb *tp = intotcpcb(inp); 328 329 if (tp) 330 tp->snd_cwnd = tp->t_maxseg; 331 } 332