| 1 | /* tcp_subr.c 4.37 82/12/16 */ |
| 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 "../netinet/in.h" |
| 10 | #include "../net/route.h" |
| 11 | #include "../netinet/in_pcb.h" |
| 12 | #include "../netinet/in_systm.h" |
| 13 | #include "../net/if.h" |
| 14 | #include "../netinet/ip.h" |
| 15 | #include "../netinet/ip_var.h" |
| 16 | #include "../netinet/ip_icmp.h" |
| 17 | #include "../netinet/tcp.h" |
| 18 | #include "../netinet/tcp_fsm.h" |
| 19 | #include "../netinet/tcp_seq.h" |
| 20 | #include "../netinet/tcp_timer.h" |
| 21 | #include "../netinet/tcp_var.h" |
| 22 | #include "../netinet/tcpip.h" |
| 23 | #include <errno.h> |
| 24 | |
| 25 | /* |
| 26 | * Tcp initialization |
| 27 | */ |
| 28 | tcp_init() |
| 29 | { |
| 30 | |
| 31 | tcp_iss = 1; /* wrong */ |
| 32 | tcb.inp_next = tcb.inp_prev = &tcb; |
| 33 | tcp_alpha = TCP_ALPHA; |
| 34 | tcp_beta = TCP_BETA; |
| 35 | } |
| 36 | |
| 37 | /* |
| 38 | * Create template to be used to send tcp packets on a connection. |
| 39 | * Call after host entry created, allocates an mbuf and fills |
| 40 | * in a skeletal tcp/ip header, minimizing the amount of work |
| 41 | * necessary when the connection is used. |
| 42 | */ |
| 43 | struct tcpiphdr * |
| 44 | tcp_template(tp) |
| 45 | struct tcpcb *tp; |
| 46 | { |
| 47 | register struct inpcb *inp = tp->t_inpcb; |
| 48 | register struct mbuf *m; |
| 49 | register struct tcpiphdr *n; |
| 50 | |
| 51 | m = m_get(M_WAIT, MT_HEADER); |
| 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, tlen; |
| 97 | struct route *ro = 0; |
| 98 | |
| 99 | if (tp) { |
| 100 | win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); |
| 101 | ro = &tp->t_inpcb->inp_route; |
| 102 | } |
| 103 | if (flags == 0) { |
| 104 | m = m_get(M_DONTWAIT, MT_HEADER); |
| 105 | if (m == 0) |
| 106 | return; |
| 107 | m->m_len = sizeof (struct tcpiphdr) + 1; |
| 108 | *mtod(m, struct tcpiphdr *) = *ti; |
| 109 | ti = mtod(m, struct tcpiphdr *); |
| 110 | flags = TH_ACK; |
| 111 | tlen = 1; |
| 112 | } else { |
| 113 | m = dtom(ti); |
| 114 | m_freem(m->m_next); |
| 115 | m->m_next = 0; |
| 116 | m->m_off = (int)ti - (int)m; |
| 117 | m->m_len = sizeof (struct tcpiphdr); |
| 118 | #define xchg(a,b,type) { type t; t=a; a=b; b=t; } |
| 119 | xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); |
| 120 | xchg(ti->ti_dport, ti->ti_sport, u_short); |
| 121 | #undef xchg |
| 122 | tlen = 0; |
| 123 | } |
| 124 | ti->ti_next = ti->ti_prev = 0; |
| 125 | ti->ti_x1 = 0; |
| 126 | ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); |
| 127 | ti->ti_seq = htonl(seq); |
| 128 | ti->ti_ack = htonl(ack); |
| 129 | ti->ti_x2 = 0; |
| 130 | ti->ti_off = sizeof (struct tcphdr) >> 2; |
| 131 | ti->ti_flags = flags; |
| 132 | ti->ti_win = htons((u_short)win); |
| 133 | ti->ti_urp = 0; |
| 134 | ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + tlen); |
| 135 | ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + tlen; |
| 136 | ((struct ip *)ti)->ip_ttl = TCP_TTL; |
| 137 | (void) ip_output(m, (struct mbuf *)0, ro, 0); |
| 138 | } |
| 139 | |
| 140 | /* |
| 141 | * Create a new TCP control block, making an |
| 142 | * empty reassembly queue and hooking it to the argument |
| 143 | * protocol control block. |
| 144 | */ |
| 145 | struct tcpcb * |
| 146 | tcp_newtcpcb(inp) |
| 147 | struct inpcb *inp; |
| 148 | { |
| 149 | struct mbuf *m = m_getclr(M_DONTWAIT, MT_PCB); |
| 150 | register struct tcpcb *tp; |
| 151 | |
| 152 | if (m == 0) |
| 153 | return (0); |
| 154 | tp = mtod(m, struct tcpcb *); |
| 155 | tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; |
| 156 | /* |
| 157 | * If the default maximum IP packet size is 576 bytes |
| 158 | * and a standard IP header is 20 bytes, with a TCP |
| 159 | * header of 20 bytes plus the options necessary to |
| 160 | * upgrade it to something higher, then initialize the |
| 161 | * maximum segment size to 576 - (20 + 20 + 8 + slop). |
| 162 | */ |
| 163 | tp->t_maxseg = 512; /* satisfy the rest of the world */ |
| 164 | tp->t_flags = 0; /* sends options! */ |
| 165 | tp->t_inpcb = inp; |
| 166 | inp->inp_ppcb = (caddr_t)tp; |
| 167 | return (tp); |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * Drop a TCP connection, reporting |
| 172 | * the specified error. If connection is synchronized, |
| 173 | * then send a RST to peer. |
| 174 | */ |
| 175 | tcp_drop(tp, errno) |
| 176 | struct tcpcb *tp; |
| 177 | int errno; |
| 178 | { |
| 179 | struct socket *so = tp->t_inpcb->inp_socket; |
| 180 | |
| 181 | if (TCPS_HAVERCVDSYN(tp->t_state)) { |
| 182 | tp->t_state = TCPS_CLOSED; |
| 183 | (void) tcp_output(tp); |
| 184 | } |
| 185 | so->so_error = errno; |
| 186 | tcp_close(tp); |
| 187 | } |
| 188 | |
| 189 | tcp_abort(inp) |
| 190 | struct inpcb *inp; |
| 191 | { |
| 192 | |
| 193 | tcp_close((struct tcpcb *)inp->inp_ppcb); |
| 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 | tcp_close(tp) |
| 203 | register struct tcpcb *tp; |
| 204 | { |
| 205 | register struct tcpiphdr *t; |
| 206 | struct inpcb *inp = tp->t_inpcb; |
| 207 | struct socket *so = inp->inp_socket; |
| 208 | |
| 209 | t = tp->seg_next; |
| 210 | for (; t != (struct tcpiphdr *)tp; t = (struct tcpiphdr *)t->ti_next) |
| 211 | m_freem(dtom(t)); |
| 212 | if (tp->t_template) |
| 213 | (void) m_free(dtom(tp->t_template)); |
| 214 | if (tp->t_tcpopt) |
| 215 | (void) m_free(dtom(tp->t_tcpopt)); |
| 216 | if (tp->t_ipopt) |
| 217 | (void) m_free(dtom(tp->t_ipopt)); |
| 218 | (void) m_free(dtom(tp)); |
| 219 | inp->inp_ppcb = 0; |
| 220 | soisdisconnected(so); |
| 221 | in_pcbdetach(inp); |
| 222 | } |
| 223 | |
| 224 | tcp_drain() |
| 225 | { |
| 226 | |
| 227 | } |
| 228 | |
| 229 | tcp_ctlinput(cmd, arg) |
| 230 | int cmd; |
| 231 | caddr_t arg; |
| 232 | { |
| 233 | struct in_addr *sin; |
| 234 | extern u_char inetctlerrmap[]; |
| 235 | |
| 236 | if (cmd < 0 || cmd > PRC_NCMDS) |
| 237 | return; |
| 238 | switch (cmd) { |
| 239 | |
| 240 | case PRC_ROUTEDEAD: |
| 241 | break; |
| 242 | |
| 243 | case PRC_QUENCH: |
| 244 | break; |
| 245 | |
| 246 | /* these are handled by ip */ |
| 247 | case PRC_IFDOWN: |
| 248 | case PRC_HOSTDEAD: |
| 249 | case PRC_HOSTUNREACH: |
| 250 | break; |
| 251 | |
| 252 | default: |
| 253 | sin = &((struct icmp *)arg)->icmp_ip.ip_dst; |
| 254 | in_pcbnotify(&tcb, sin, (int)inetctlerrmap[cmd], tcp_abort); |
| 255 | } |
| 256 | } |