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 7.3 (Berkeley) 02/19/87 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 struct mbuf *m; 106 int win = 0, tlen; 107 struct route *ro = 0; 108 109 if (tp) { 110 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 111 ro = &tp->t_inpcb->inp_route; 112 } 113 if (flags == 0) { 114 m = m_get(M_DONTWAIT, MT_HEADER); 115 if (m == NULL) 116 return; 117 m->m_len = sizeof (struct tcpiphdr) + 1; 118 *mtod(m, struct tcpiphdr *) = *ti; 119 ti = mtod(m, struct tcpiphdr *); 120 flags = TH_ACK; 121 } else { 122 m = dtom(ti); 123 m_freem(m->m_next); 124 m->m_next = 0; 125 m->m_off = (int)ti - (int)m; 126 m->m_len = sizeof (struct tcpiphdr); 127 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 128 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 129 xchg(ti->ti_dport, ti->ti_sport, u_short); 130 #undef xchg 131 } 132 tlen = 0; 133 ti->ti_next = ti->ti_prev = 0; 134 ti->ti_x1 = 0; 135 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 136 ti->ti_seq = htonl(seq); 137 ti->ti_ack = htonl(ack); 138 ti->ti_x2 = 0; 139 ti->ti_off = sizeof (struct tcphdr) >> 2; 140 ti->ti_flags = flags; 141 ti->ti_win = htons((u_short)win); 142 ti->ti_urp = 0; 143 ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + tlen); 144 ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + tlen; 145 ((struct ip *)ti)->ip_ttl = TCP_TTL; 146 (void) ip_output(m, (struct mbuf *)0, ro, 0); 147 } 148 149 /* 150 * Create a new TCP control block, making an 151 * empty reassembly queue and hooking it to the argument 152 * protocol control block. 153 */ 154 struct tcpcb * 155 tcp_newtcpcb(inp) 156 struct inpcb *inp; 157 { 158 struct mbuf *m = m_getclr(M_DONTWAIT, MT_PCB); 159 register struct tcpcb *tp; 160 161 if (m == NULL) 162 return ((struct tcpcb *)0); 163 tp = mtod(m, struct tcpcb *); 164 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 165 tp->t_maxseg = TCP_MSS; 166 tp->t_flags = 0; /* sends options! */ 167 tp->t_inpcb = inp; 168 tp->t_srtt = TCPTV_SRTTBASE; 169 tp->snd_cwnd = sbspace(&inp->inp_socket->so_snd); 170 inp->inp_ppcb = (caddr_t)tp; 171 return (tp); 172 } 173 174 /* 175 * Drop a TCP connection, reporting 176 * the specified error. If connection is synchronized, 177 * then send a RST to peer. 178 */ 179 struct tcpcb * 180 tcp_drop(tp, errno) 181 register struct tcpcb *tp; 182 int errno; 183 { 184 struct socket *so = tp->t_inpcb->inp_socket; 185 186 if (TCPS_HAVERCVDSYN(tp->t_state)) { 187 tp->t_state = TCPS_CLOSED; 188 (void) tcp_output(tp); 189 tcpstat.tcps_drops++; 190 } else 191 tcpstat.tcps_conndrops++; 192 so->so_error = errno; 193 return (tcp_close(tp)); 194 } 195 196 /* 197 * Close a TCP control block: 198 * discard all space held by the tcp 199 * discard internet protocol block 200 * wake up any sleepers 201 */ 202 struct tcpcb * 203 tcp_close(tp) 204 register struct tcpcb *tp; 205 { 206 register struct tcpiphdr *t; 207 struct inpcb *inp = tp->t_inpcb; 208 struct socket *so = inp->inp_socket; 209 register struct mbuf *m; 210 211 t = tp->seg_next; 212 while (t != (struct tcpiphdr *)tp) { 213 t = (struct tcpiphdr *)t->ti_next; 214 m = dtom(t->ti_prev); 215 remque(t->ti_prev); 216 m_freem(m); 217 } 218 if (tp->t_template) 219 (void) m_free(dtom(tp->t_template)); 220 if (tp->t_tcpopt) 221 (void) m_free(dtom(tp->t_tcpopt)); 222 (void) m_free(dtom(tp)); 223 inp->inp_ppcb = 0; 224 soisdisconnected(so); 225 in_pcbdetach(inp); 226 tcpstat.tcps_closed++; 227 return ((struct tcpcb *)0); 228 } 229 230 tcp_drain() 231 { 232 233 } 234 235 /* 236 * Notify a tcp user of an asynchronous error; 237 * just wake up so that he can collect error status. 238 */ 239 tcp_notify(inp) 240 register struct inpcb *inp; 241 { 242 243 wakeup((caddr_t) &inp->inp_socket->so_timeo); 244 sorwakeup(inp->inp_socket); 245 sowwakeup(inp->inp_socket); 246 } 247 tcp_ctlinput(cmd, sa) 248 int cmd; 249 struct sockaddr *sa; 250 { 251 extern u_char inetctlerrmap[]; 252 struct sockaddr_in *sin; 253 int tcp_quench(), in_rtchange(); 254 255 if ((unsigned)cmd > PRC_NCMDS) 256 return; 257 if (sa->sa_family != AF_INET && sa->sa_family != AF_IMPLINK) 258 return; 259 sin = (struct sockaddr_in *)sa; 260 if (sin->sin_addr.s_addr == INADDR_ANY) 261 return; 262 263 switch (cmd) { 264 265 case PRC_QUENCH: 266 in_pcbnotify(&tcb, &sin->sin_addr, 0, tcp_quench); 267 break; 268 269 case PRC_ROUTEDEAD: 270 case PRC_REDIRECT_NET: 271 case PRC_REDIRECT_HOST: 272 case PRC_REDIRECT_TOSNET: 273 case PRC_REDIRECT_TOSHOST: 274 in_pcbnotify(&tcb, &sin->sin_addr, 0, in_rtchange); 275 break; 276 277 default: 278 if (inetctlerrmap[cmd] == 0) 279 return; /* XXX */ 280 in_pcbnotify(&tcb, &sin->sin_addr, (int)inetctlerrmap[cmd], 281 tcp_notify); 282 } 283 } 284 285 /* 286 * When a source quench is received, close congestion window 287 * to 80% of the outstanding data (but not less than one segment). 288 */ 289 tcp_quench(inp) 290 struct inpcb *inp; 291 { 292 struct tcpcb *tp = intotcpcb(inp); 293 294 if (tp) 295 tp->snd_cwnd = MAX(8 * (tp->snd_nxt - tp->snd_una) / 10, 296 tp->t_maxseg); 297 } 298