1 /* 2 * Copyright (c) 1982 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 6.6 (Berkeley) 06/08/85 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 m = m_get(M_WAIT, MT_HEADER); 60 if (m == NULL) 61 return (0); 62 m->m_off = MMAXOFF - sizeof (struct tcpiphdr); 63 m->m_len = sizeof (struct tcpiphdr); 64 n = mtod(m, struct tcpiphdr *); 65 n->ti_next = n->ti_prev = 0; 66 n->ti_x1 = 0; 67 n->ti_pr = IPPROTO_TCP; 68 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 69 n->ti_src = inp->inp_laddr; 70 n->ti_dst = inp->inp_faddr; 71 n->ti_sport = inp->inp_lport; 72 n->ti_dport = inp->inp_fport; 73 n->ti_seq = 0; 74 n->ti_ack = 0; 75 n->ti_x2 = 0; 76 n->ti_off = 5; 77 n->ti_flags = 0; 78 n->ti_win = 0; 79 n->ti_sum = 0; 80 n->ti_urp = 0; 81 return (n); 82 } 83 84 /* 85 * Send a single message to the TCP at address specified by 86 * the given TCP/IP header. If flags==0, then we make a copy 87 * of the tcpiphdr at ti and send directly to the addressed host. 88 * This is used to force keep alive messages out using the TCP 89 * template for a connection tp->t_template. If flags are given 90 * then we send a message back to the TCP which originated the 91 * segment ti, and discard the mbuf containing it and any other 92 * attached mbufs. 93 * 94 * In any case the ack and sequence number of the transmitted 95 * segment are as specified by the parameters. 96 */ 97 tcp_respond(tp, ti, ack, seq, flags) 98 struct tcpcb *tp; 99 register struct tcpiphdr *ti; 100 tcp_seq ack, seq; 101 int flags; 102 { 103 struct mbuf *m; 104 int win = 0, tlen; 105 struct route *ro = 0; 106 107 if (tp) { 108 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 109 ro = &tp->t_inpcb->inp_route; 110 } 111 if (flags == 0) { 112 m = m_get(M_DONTWAIT, MT_HEADER); 113 if (m == NULL) 114 return; 115 m->m_len = sizeof (struct tcpiphdr) + 1; 116 *mtod(m, struct tcpiphdr *) = *ti; 117 ti = mtod(m, struct tcpiphdr *); 118 flags = TH_ACK; 119 tlen = 1; 120 } else { 121 m = dtom(ti); 122 m_freem(m->m_next); 123 m->m_next = 0; 124 m->m_off = (int)ti - (int)m; 125 m->m_len = sizeof (struct tcpiphdr); 126 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 127 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 128 xchg(ti->ti_dport, ti->ti_sport, u_short); 129 #undef xchg 130 tlen = 0; 131 } 132 ti->ti_next = ti->ti_prev = 0; 133 ti->ti_x1 = 0; 134 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 135 ti->ti_seq = htonl(seq); 136 ti->ti_ack = htonl(ack); 137 ti->ti_x2 = 0; 138 ti->ti_off = sizeof (struct tcphdr) >> 2; 139 ti->ti_flags = flags; 140 ti->ti_win = htons((u_short)win); 141 ti->ti_urp = 0; 142 ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + tlen); 143 ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + tlen; 144 ((struct ip *)ti)->ip_ttl = TCP_TTL; 145 (void) ip_output(m, (struct mbuf *)0, ro, 0); 146 } 147 148 /* 149 * Create a new TCP control block, making an 150 * empty reassembly queue and hooking it to the argument 151 * protocol control block. 152 */ 153 struct tcpcb * 154 tcp_newtcpcb(inp) 155 struct inpcb *inp; 156 { 157 struct mbuf *m = m_getclr(M_DONTWAIT, MT_PCB); 158 register struct tcpcb *tp; 159 160 if (m == NULL) 161 return ((struct tcpcb *)0); 162 tp = mtod(m, struct tcpcb *); 163 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 164 tp->t_maxseg = TCP_MSS; 165 tp->t_flags = 0; /* sends options! */ 166 tp->t_inpcb = inp; 167 tp->t_srtt = TCPTV_SRTTBASE; 168 tp->snd_cwnd = sbspace(&inp->inp_socket->so_snd); 169 inp->inp_ppcb = (caddr_t)tp; 170 return (tp); 171 } 172 173 /* 174 * Drop a TCP connection, reporting 175 * the specified error. If connection is synchronized, 176 * then send a RST to peer. 177 */ 178 struct tcpcb * 179 tcp_drop(tp, errno) 180 register struct tcpcb *tp; 181 int errno; 182 { 183 struct socket *so = tp->t_inpcb->inp_socket; 184 185 if (TCPS_HAVERCVDSYN(tp->t_state)) { 186 tp->t_state = TCPS_CLOSED; 187 (void) tcp_output(tp); 188 } 189 so->so_error = errno; 190 return (tcp_close(tp)); 191 } 192 193 tcp_abort(inp) 194 struct inpcb *inp; 195 { 196 197 (void) tcp_close((struct tcpcb *)inp->inp_ppcb); 198 } 199 200 /* 201 * Close a TCP control block: 202 * discard all space held by the tcp 203 * discard internet protocol block 204 * wake up any sleepers 205 */ 206 struct tcpcb * 207 tcp_close(tp) 208 register struct tcpcb *tp; 209 { 210 register struct tcpiphdr *t; 211 struct inpcb *inp = tp->t_inpcb; 212 struct socket *so = inp->inp_socket; 213 register struct mbuf *m; 214 215 t = tp->seg_next; 216 while (t != (struct tcpiphdr *)tp) { 217 t = (struct tcpiphdr *)t->ti_next; 218 m = dtom(t->ti_prev); 219 remque(t->ti_prev); 220 m_freem(m); 221 } 222 if (tp->t_template) 223 (void) m_free(dtom(tp->t_template)); 224 if (tp->t_tcpopt) 225 (void) m_free(dtom(tp->t_tcpopt)); 226 if (tp->t_ipopt) 227 (void) m_free(dtom(tp->t_ipopt)); 228 (void) m_free(dtom(tp)); 229 inp->inp_ppcb = 0; 230 soisdisconnected(so); 231 in_pcbdetach(inp); 232 return ((struct tcpcb *)0); 233 } 234 235 tcp_drain() 236 { 237 238 } 239 240 tcp_ctlinput(cmd, arg) 241 int cmd; 242 caddr_t arg; 243 { 244 struct in_addr *in; 245 extern u_char inetctlerrmap[]; 246 int tcp_quench(), in_rtchange(); 247 248 if (cmd < 0 || cmd > PRC_NCMDS) 249 return; 250 switch (cmd) { 251 252 case PRC_ROUTEDEAD: 253 break; 254 255 case PRC_QUENCH: 256 in = &((struct icmp *)arg)->icmp_ip.ip_dst; 257 in_pcbnotify(&tcb, in, 0, tcp_quench); 258 break; 259 260 case PRC_REDIRECT_NET: 261 case PRC_REDIRECT_HOST: 262 in = &((struct icmp *)arg)->icmp_ip.ip_dst; 263 in_pcbnotify(&tcb, in, 0, in_rtchange); 264 break; 265 266 case PRC_IFDOWN: 267 in = &((struct sockaddr_in *)arg)->sin_addr; 268 goto notify; 269 270 case PRC_HOSTDEAD: 271 case PRC_HOSTUNREACH: 272 in = (struct in_addr *)arg; 273 goto notify; 274 275 default: 276 if (inetctlerrmap[cmd] == 0) 277 return; /* XXX */ 278 in = &((struct icmp *)arg)->icmp_ip.ip_dst; 279 notify: 280 in_pcbnotify(&tcb, in, (int)inetctlerrmap[cmd], tcp_abort); 281 } 282 } 283 284 /* 285 * When a source quench is received, close congestion window 286 * to 80% of the outstanding data (but not less than one segment). 287 */ 288 tcp_quench(inp) 289 struct inpcb *inp; 290 { 291 struct tcpcb *tp = intotcpcb(inp); 292 293 tp->snd_cwnd = MAX(8 * (tp->snd_nxt - tp->snd_una) / 10, tp->t_maxseg); 294 } 295