1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 * 6 * @(#)tcp_subr.c 7.4 (Berkeley) 04/02/87 7 */ 8 9 #include "param.h" 10 #include "systm.h" 11 #include "mbuf.h" 12 #include "socket.h" 13 #include "socketvar.h" 14 #include "protosw.h" 15 #include "errno.h" 16 17 #include "../net/route.h" 18 #include "../net/if.h" 19 20 #include "in.h" 21 #include "in_pcb.h" 22 #include "in_systm.h" 23 #include "ip.h" 24 #include "ip_var.h" 25 #include "ip_icmp.h" 26 #include "tcp.h" 27 #include "tcp_fsm.h" 28 #include "tcp_seq.h" 29 #include "tcp_timer.h" 30 #include "tcp_var.h" 31 #include "tcpip.h" 32 33 /* 34 * Tcp initialization 35 */ 36 tcp_init() 37 { 38 39 tcp_iss = 1; /* wrong */ 40 tcb.inp_next = tcb.inp_prev = &tcb; 41 tcp_alpha = TCP_ALPHA; 42 tcp_beta = TCP_BETA; 43 } 44 45 /* 46 * Create template to be used to send tcp packets on a connection. 47 * Call after host entry created, allocates an mbuf and fills 48 * in a skeletal tcp/ip header, minimizing the amount of work 49 * necessary when the connection is used. 50 */ 51 struct tcpiphdr * 52 tcp_template(tp) 53 struct tcpcb *tp; 54 { 55 register struct inpcb *inp = tp->t_inpcb; 56 register struct mbuf *m; 57 register struct tcpiphdr *n; 58 59 if ((n = tp->t_template) == 0) { 60 m = m_get(M_WAIT, MT_HEADER); 61 if (m == NULL) 62 return (0); 63 m->m_off = MMAXOFF - sizeof (struct tcpiphdr); 64 m->m_len = sizeof (struct tcpiphdr); 65 n = mtod(m, struct tcpiphdr *); 66 } 67 n->ti_next = n->ti_prev = 0; 68 n->ti_x1 = 0; 69 n->ti_pr = IPPROTO_TCP; 70 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 71 n->ti_src = inp->inp_laddr; 72 n->ti_dst = inp->inp_faddr; 73 n->ti_sport = inp->inp_lport; 74 n->ti_dport = inp->inp_fport; 75 n->ti_seq = 0; 76 n->ti_ack = 0; 77 n->ti_x2 = 0; 78 n->ti_off = 5; 79 n->ti_flags = 0; 80 n->ti_win = 0; 81 n->ti_sum = 0; 82 n->ti_urp = 0; 83 return (n); 84 } 85 86 /* 87 * Send a single message to the TCP at address specified by 88 * the given TCP/IP header. If flags==0, then we make a copy 89 * of the tcpiphdr at ti and send directly to the addressed host. 90 * This is used to force keep alive messages out using the TCP 91 * template for a connection tp->t_template. If flags are given 92 * then we send a message back to the TCP which originated the 93 * segment ti, and discard the mbuf containing it and any other 94 * attached mbufs. 95 * 96 * In any case the ack and sequence number of the transmitted 97 * segment are as specified by the parameters. 98 */ 99 tcp_respond(tp, ti, ack, seq, flags) 100 struct tcpcb *tp; 101 register struct tcpiphdr *ti; 102 tcp_seq ack, seq; 103 int flags; 104 { 105 register struct mbuf *m; 106 int win = 0, tlen; 107 struct route *ro = 0; 108 extern int tcp_keeplen; 109 110 if (tp) { 111 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 112 ro = &tp->t_inpcb->inp_route; 113 } 114 if (flags == 0) { 115 m = m_get(M_DONTWAIT, MT_HEADER); 116 if (m == NULL) 117 return; 118 tlen = tcp_keeplen; 119 m->m_len = sizeof (struct tcpiphdr) + tlen; 120 *mtod(m, struct tcpiphdr *) = *ti; 121 ti = mtod(m, struct tcpiphdr *); 122 flags = TH_ACK; 123 } else { 124 m = dtom(ti); 125 m_freem(m->m_next); 126 m->m_next = 0; 127 m->m_off = (int)ti - (int)m; 128 tlen = 0; 129 m->m_len = sizeof (struct tcpiphdr); 130 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 131 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 132 xchg(ti->ti_dport, ti->ti_sport, u_short); 133 #undef xchg 134 } 135 ti->ti_next = ti->ti_prev = 0; 136 ti->ti_x1 = 0; 137 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 138 ti->ti_seq = htonl(seq); 139 ti->ti_ack = htonl(ack); 140 ti->ti_x2 = 0; 141 ti->ti_off = sizeof (struct tcphdr) >> 2; 142 ti->ti_flags = flags; 143 ti->ti_win = htons((u_short)win); 144 ti->ti_urp = 0; 145 ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + tlen); 146 ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + tlen; 147 ((struct ip *)ti)->ip_ttl = TCP_TTL; 148 (void) ip_output(m, (struct mbuf *)0, ro, 0); 149 } 150 151 /* 152 * Create a new TCP control block, making an 153 * empty reassembly queue and hooking it to the argument 154 * protocol control block. 155 */ 156 struct tcpcb * 157 tcp_newtcpcb(inp) 158 struct inpcb *inp; 159 { 160 struct mbuf *m = m_getclr(M_DONTWAIT, MT_PCB); 161 register struct tcpcb *tp; 162 163 if (m == NULL) 164 return ((struct tcpcb *)0); 165 tp = mtod(m, struct tcpcb *); 166 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 167 tp->t_maxseg = TCP_MSS; 168 tp->t_flags = 0; /* sends options! */ 169 tp->t_inpcb = inp; 170 tp->t_srtt = TCPTV_SRTTBASE; 171 tp->snd_cwnd = sbspace(&inp->inp_socket->so_snd); 172 inp->inp_ppcb = (caddr_t)tp; 173 return (tp); 174 } 175 176 /* 177 * Drop a TCP connection, reporting 178 * the specified error. If connection is synchronized, 179 * then send a RST to peer. 180 */ 181 struct tcpcb * 182 tcp_drop(tp, errno) 183 register struct tcpcb *tp; 184 int errno; 185 { 186 struct socket *so = tp->t_inpcb->inp_socket; 187 188 if (TCPS_HAVERCVDSYN(tp->t_state)) { 189 tp->t_state = TCPS_CLOSED; 190 (void) tcp_output(tp); 191 tcpstat.tcps_drops++; 192 } else 193 tcpstat.tcps_conndrops++; 194 so->so_error = errno; 195 return (tcp_close(tp)); 196 } 197 198 /* 199 * Close a TCP control block: 200 * discard all space held by the tcp 201 * discard internet protocol block 202 * wake up any sleepers 203 */ 204 struct tcpcb * 205 tcp_close(tp) 206 register struct tcpcb *tp; 207 { 208 register struct tcpiphdr *t; 209 struct inpcb *inp = tp->t_inpcb; 210 struct socket *so = inp->inp_socket; 211 register struct mbuf *m; 212 213 t = tp->seg_next; 214 while (t != (struct tcpiphdr *)tp) { 215 t = (struct tcpiphdr *)t->ti_next; 216 m = dtom(t->ti_prev); 217 remque(t->ti_prev); 218 m_freem(m); 219 } 220 if (tp->t_template) 221 (void) m_free(dtom(tp->t_template)); 222 if (tp->t_tcpopt) 223 (void) m_free(dtom(tp->t_tcpopt)); 224 (void) m_free(dtom(tp)); 225 inp->inp_ppcb = 0; 226 soisdisconnected(so); 227 in_pcbdetach(inp); 228 tcpstat.tcps_closed++; 229 return ((struct tcpcb *)0); 230 } 231 232 tcp_drain() 233 { 234 235 } 236 237 /* 238 * Notify a tcp user of an asynchronous error; 239 * just wake up so that he can collect error status. 240 */ 241 tcp_notify(inp) 242 register struct inpcb *inp; 243 { 244 245 wakeup((caddr_t) &inp->inp_socket->so_timeo); 246 sorwakeup(inp->inp_socket); 247 sowwakeup(inp->inp_socket); 248 } 249 tcp_ctlinput(cmd, sa) 250 int cmd; 251 struct sockaddr *sa; 252 { 253 extern u_char inetctlerrmap[]; 254 struct sockaddr_in *sin; 255 int tcp_quench(), in_rtchange(); 256 257 if ((unsigned)cmd > PRC_NCMDS) 258 return; 259 if (sa->sa_family != AF_INET && sa->sa_family != AF_IMPLINK) 260 return; 261 sin = (struct sockaddr_in *)sa; 262 if (sin->sin_addr.s_addr == INADDR_ANY) 263 return; 264 265 switch (cmd) { 266 267 case PRC_QUENCH: 268 in_pcbnotify(&tcb, &sin->sin_addr, 0, tcp_quench); 269 break; 270 271 case PRC_ROUTEDEAD: 272 case PRC_REDIRECT_NET: 273 case PRC_REDIRECT_HOST: 274 case PRC_REDIRECT_TOSNET: 275 case PRC_REDIRECT_TOSHOST: 276 in_pcbnotify(&tcb, &sin->sin_addr, 0, in_rtchange); 277 break; 278 279 default: 280 if (inetctlerrmap[cmd] == 0) 281 return; /* XXX */ 282 in_pcbnotify(&tcb, &sin->sin_addr, (int)inetctlerrmap[cmd], 283 tcp_notify); 284 } 285 } 286 287 /* 288 * When a source quench is received, close congestion window 289 * to 80% of the outstanding data (but not less than one segment). 290 */ 291 tcp_quench(inp) 292 struct inpcb *inp; 293 { 294 struct tcpcb *tp = intotcpcb(inp); 295 296 if (tp) 297 tp->snd_cwnd = MAX(8 * (tp->snd_nxt - tp->snd_una) / 10, 298 tp->t_maxseg); 299 } 300