1 /* tcp_subr.c 4.12 82/01/13 */ 2 3 #include "../h/param.h" 4 #include "../h/systm.h" 5 #include "../h/mbuf.h" 6 #include "../h/socket.h" 7 #include "../h/socketvar.h" 8 #include "../h/protosw.h" 9 #include "../net/in.h" 10 #include "../net/in_pcb.h" 11 #include "../net/in_systm.h" 12 #include "../net/if.h" 13 #include "../net/ip.h" 14 #include "../net/ip_var.h" 15 #include "../net/tcp.h" 16 #include "../net/tcp_fsm.h" 17 #include "../net/tcp_seq.h" 18 #include "../net/tcp_timer.h" 19 #include "../net/tcp_var.h" 20 #include "../net/tcpip.h" 21 #include "../errno.h" 22 23 /* 24 * Tcp initialization 25 */ 26 tcp_init() 27 { 28 29 COUNT(TCP_INIT); 30 tcp_iss = 1; /* wrong */ 31 tcb.inp_next = tcb.inp_prev = &tcb; 32 tcp_alpha = TCP_ALPHA; 33 tcp_beta = TCP_BETA; 34 } 35 36 /* 37 * Create template to be used to send tcp packets on a connection. 38 * Call after host entry created, allocates an mbuf and fills 39 * in a skeletal tcp/ip header, minimizing the amount of work 40 * necessary when the connection is used. 41 */ 42 struct tcpiphdr * 43 tcp_template(tp) 44 struct tcpcb *tp; 45 { 46 register struct inpcb *inp = tp->t_inpcb; 47 register struct mbuf *m; 48 register struct tcpiphdr *n; 49 50 COUNT(TCP_TEMPLATE); 51 m = m_get(1); 52 if (m == 0) 53 return (0); 54 m->m_off = MMAXOFF - sizeof (struct tcpiphdr); 55 m->m_len = sizeof (struct tcpiphdr); 56 n = mtod(m, struct tcpiphdr *); 57 n->ti_next = n->ti_prev = 0; 58 n->ti_x1 = 0; 59 n->ti_pr = IPPROTO_TCP; 60 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 61 n->ti_src = inp->inp_laddr; 62 n->ti_dst = inp->inp_faddr; 63 n->ti_sport = inp->inp_lport; 64 n->ti_dport = inp->inp_fport; 65 n->ti_seq = 0; 66 n->ti_ack = 0; 67 n->ti_x2 = 0; 68 n->ti_off = 5; 69 n->ti_flags = 0; 70 n->ti_win = 0; 71 n->ti_sum = 0; 72 n->ti_urp = 0; 73 return (n); 74 } 75 76 /* 77 * Send a single message to the TCP at address specified by 78 * the given TCP/IP header. If flags==0, then we make a copy 79 * of the tcpiphdr at ti and send directly to the addressed host. 80 * This is used to force keep alive messages out using the TCP 81 * template for a connection tp->t_template. If flags are given 82 * then we send a message back to the TCP which originated the 83 * segment ti, and discard the mbuf containing it and any other 84 * attached mbufs. 85 * 86 * In any case the ack and sequence number of the transmitted 87 * segment are as specified by the parameters. 88 */ 89 tcp_respond(tp, ti, ack, seq, flags) 90 struct tcpcb *tp; 91 register struct tcpiphdr *ti; 92 tcp_seq ack, seq; 93 int flags; 94 { 95 struct mbuf *m; 96 int win = 0; 97 98 COUNT(TCP_RESPOND); 99 if (tp) 100 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 101 if (flags == 0) { 102 m = m_get(0); 103 if (m == 0) 104 return; 105 m->m_off = MMINOFF; 106 m->m_len = sizeof (struct tcpiphdr); 107 *mtod(m, struct tcpiphdr *) = *ti; 108 ti = mtod(m, struct tcpiphdr *); 109 flags = TH_ACK; 110 } else { 111 m = dtom(ti); 112 m_freem(m->m_next); 113 m->m_next = 0; 114 m->m_len = sizeof (struct tcpiphdr); 115 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 116 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 117 xchg(ti->ti_dport, ti->ti_sport, u_short); 118 #undef xchg 119 } 120 ti->ti_next = ti->ti_prev = 0; 121 ti->ti_x1 = 0; 122 ti->ti_len = sizeof (struct tcphdr); 123 ti->ti_seq = seq; 124 ti->ti_ack = ack; 125 #if vax 126 ti->ti_len = htons(ti->ti_len); 127 ti->ti_seq = htonl(ti->ti_seq); 128 ti->ti_ack = htonl(ti->ti_ack); 129 #endif 130 ti->ti_x2 = 0; 131 ti->ti_off = sizeof (struct tcphdr) >> 2; 132 ti->ti_flags = flags; 133 ti->ti_win = win; 134 #if vax 135 ti->ti_win = htons(ti->ti_win); 136 #endif 137 ti->ti_urp = 0; 138 ti->ti_sum = in_cksum(m, sizeof(struct tcpiphdr)); 139 ((struct ip *)ti)->ip_len = sizeof(struct tcpiphdr); 140 ((struct ip *)ti)->ip_ttl = TCP_TTL; 141 (void) ip_output(m, (struct mbuf *)0); 142 } 143 144 /* 145 * Create a new TCP control block, making an 146 * empty reassembly queue and hooking it to the argument 147 * protocol control block. 148 */ 149 struct tcpcb * 150 tcp_newtcpcb(inp) 151 struct inpcb *inp; 152 { 153 struct mbuf *m = m_getclr(0); 154 register struct tcpcb *tp; 155 COUNT(TCP_NEWTCPCB); 156 157 if (m == 0) 158 return (0); 159 tp = mtod(m, struct tcpcb *); 160 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 161 tp->t_maxseg = 1024; 162 tp->t_inpcb = inp; 163 inp->inp_ppcb = (caddr_t)tp; 164 return (tp); 165 } 166 167 /* 168 * Drop a TCP connection, reporting 169 * the specified error. If connection is synchronized, 170 * then send a RST to peer. 171 */ 172 tcp_drop(tp, errno) 173 struct tcpcb *tp; 174 int errno; 175 { 176 struct socket *so = tp->t_inpcb->inp_socket; 177 178 COUNT(TCP_DROP); 179 if (TCPS_HAVERCVDSYN(tp->t_state)) { 180 tp->t_state = TCPS_CLOSED; 181 tcp_output(tp); 182 } 183 so->so_error = errno; 184 tcp_close(tp); 185 } 186 187 /* 188 * Close a TCP control block: 189 * discard all space held by the tcp 190 * discard internet protocol block 191 * wake up any sleepers 192 */ 193 tcp_close(tp) 194 register struct tcpcb *tp; 195 { 196 register struct tcpiphdr *t; 197 struct inpcb *inp = tp->t_inpcb; 198 struct socket *so = inp->inp_socket; 199 200 COUNT(TCP_CLOSE); 201 t = tp->seg_next; 202 for (; t != (struct tcpiphdr *)tp; t = (struct tcpiphdr *)t->ti_next) 203 m_freem(dtom(t)); 204 if (tp->t_template) 205 (void) m_free(dtom(tp->t_template)); 206 if (tp->t_tcpopt) 207 (void) m_free(dtom(tp->t_tcpopt)); 208 if (tp->t_ipopt) 209 (void) m_free(dtom(tp->t_ipopt)); 210 (void) m_free(dtom(tp)); 211 inp->inp_ppcb = 0; 212 in_pcbdetach(inp); 213 soisdisconnected(so); 214 } 215 216 tcp_drain() 217 { 218 219 COUNT(TCP_DRAIN); 220 } 221 222 tcp_ctlinput(m) 223 struct mbuf *m; 224 { 225 226 COUNT(TCP_CTLINPUT); 227 m_freem(m); 228 } 229