1 /* tcp_subr.c 4.6 81/12/03 */ 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(ti, ack, seq, flags) 90 register struct tcpiphdr *ti; 91 tcp_seq ack, seq; 92 int flags; 93 { 94 struct mbuf *m; 95 96 COUNT(TCP_RESPOND); 97 if (flags == 0) { 98 m = m_get(0); 99 if (m == 0) 100 return; 101 m->m_off = MMINOFF; 102 m->m_len = sizeof (struct tcpiphdr); 103 *mtod(m, struct tcpiphdr *) = *ti; 104 ti = mtod(m, struct tcpiphdr *); 105 flags = TH_ACK; 106 } else { 107 m_freem(m->m_next); 108 m->m_next = 0; 109 m->m_len = sizeof (struct tcpiphdr); 110 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 111 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 112 xchg(ti->ti_dport, ti->ti_sport, u_short); 113 #undef xchg 114 } 115 ti->ti_next = ti->ti_prev = 0; 116 ti->ti_x1 = 0; 117 ti->ti_len = htons(sizeof (struct tcphdr)); 118 ti->ti_seq = htonl(seq); 119 ti->ti_ack = htonl(ack); 120 ti->ti_x2 = 0; 121 ti->ti_off = sizeof (struct tcphdr) >> 2; 122 ti->ti_flags = flags; 123 ti->ti_win = ti->ti_urp = 0; 124 ti->ti_sum = in_cksum(m, sizeof(struct tcpiphdr)); 125 ((struct ip *)ti)->ip_len = sizeof(struct tcpiphdr); 126 ((struct ip *)ti)->ip_ttl = TCP_TTL; 127 (void) ip_output(m, (struct mbuf *)0); 128 } 129 130 /* 131 * Create a new TCP control block, making an 132 * empty reassembly queue and hooking it to the argument 133 * protocol control block. 134 */ 135 struct tcpcb * 136 tcp_newtcpcb(inp) 137 struct inpcb *inp; 138 { 139 struct mbuf *m = m_getclr(0); 140 register struct tcpcb *tp; 141 COUNT(TCP_NEWTCPCB); 142 143 if (m == 0) 144 return (0); 145 tp = mtod(m, struct tcpcb *); 146 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 147 tp->t_maxseg = 1024; 148 tp->t_inpcb = inp; 149 inp->inp_ppcb = (caddr_t)tp; 150 return (tp); 151 } 152 153 /* 154 * Drop a TCP connection, reporting 155 * the specified error. If connection is synchronized, 156 * then send a RST to peer. 157 */ 158 tcp_drop(tp, errno) 159 struct tcpcb *tp; 160 int errno; 161 { 162 struct socket *so = tp->t_inpcb->inp_socket; 163 164 COUNT(TCP_DROP); 165 if (TCPS_HAVERCVDSYN(tp->t_state) && 166 TCPS_OURFINNOTACKED(tp->t_state)) { 167 tp->t_state = TCPS_CLOSED; 168 tcp_output(tp); 169 } 170 so->so_error = errno; 171 tcp_close(tp); 172 in_pcbdetach(tp->t_inpcb); 173 } 174 175 /* 176 * Close a TCP control block: 177 * discard all space held by the tcp 178 * discard internet protocol block 179 * wake up any sleepers 180 */ 181 tcp_close(tp) 182 register struct tcpcb *tp; 183 { 184 register struct tcpiphdr *t; 185 struct socket *so = tp->t_inpcb->inp_socket; 186 187 COUNT(TCP_CLOSE); 188 t = tp->seg_next; 189 for (; t != (struct tcpiphdr *)tp; t = (struct tcpiphdr *)t->ti_next) 190 m_freem(dtom(t)); 191 if (tp->t_template) 192 (void) m_free(dtom(tp->t_template)); 193 if (tp->t_tcpopt) 194 (void) m_free(dtom(tp->t_tcpopt)); 195 if (tp->t_ipopt) 196 (void) m_free(dtom(tp->t_ipopt)); 197 (void) m_free(dtom(tp)); 198 socantrcvmore(so); 199 socantsendmore(so); 200 in_pcbdisconnect(tp->t_inpcb); 201 } 202 203 tcp_drain() 204 { 205 206 COUNT(TCP_DRAIN); 207 } 208 209 tcp_ctlinput(m) 210 struct mbuf *m; 211 { 212 213 COUNT(TCP_CTLINPUT); 214 m_freem(m); 215 } 216