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1.1 root 1: /* tcp_subr.c 6.1 83/07/29 */
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 "../h/errno.h"
10:
11: #include "../net/route.h"
12: #include "../net/if.h"
13:
14: #include "../netinet/in.h"
15: #include "../netinet/in_pcb.h"
16: #include "../netinet/in_systm.h"
17: #include "../netinet/ip.h"
18: #include "../netinet/ip_var.h"
19: #include "../netinet/ip_icmp.h"
20: #include "../netinet/tcp.h"
21: #include "../netinet/tcp_fsm.h"
22: #include "../netinet/tcp_seq.h"
23: #include "../netinet/tcp_timer.h"
24: #include "../netinet/tcp_var.h"
25: #include "../netinet/tcpip.h"
26:
27: /*
28: * Changes
29: * . from Usenet: set default max seg to 536 bytes (as
30: * mentioned by POSTEL <INC-PROJECT, MAX-SEG-SIZ.NLS.14>
31: * & letter of 7 Nov 1983.
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: MBUFNULL(14, m); /* for debugging */
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: n->ti_next = n->ti_prev = 0;
67: n->ti_x1 = 0;
68: n->ti_pr = IPPROTO_TCP;
69: n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
70: n->ti_src = inp->inp_laddr;
71: n->ti_dst = inp->inp_faddr;
72: n->ti_sport = inp->inp_lport;
73: n->ti_dport = inp->inp_fport;
74: n->ti_seq = 0;
75: n->ti_ack = 0;
76: n->ti_x2 = 0;
77: n->ti_off = 5;
78: n->ti_flags = 0;
79: n->ti_win = 0;
80: n->ti_sum = 0;
81: n->ti_urp = 0;
82: return (n);
83: }
84:
85: /*
86: * Send a single message to the TCP at address specified by
87: * the given TCP/IP header. If flags==0, then we make a copy
88: * of the tcpiphdr at ti and send directly to the addressed host.
89: * This is used to force keep alive messages out using the TCP
90: * template for a connection tp->t_template. If flags are given
91: * then we send a message back to the TCP which originated the
92: * segment ti, and discard the mbuf containing it and any other
93: * attached mbufs.
94: *
95: * In any case the ack and sequence number of the transmitted
96: * segment are as specified by the parameters.
97: */
98: tcp_respond(tp, ti, ack, seq, flags)
99: struct tcpcb *tp;
100: register struct tcpiphdr *ti;
101: tcp_seq ack, seq;
102: int flags;
103: {
104: struct mbuf *m;
105: int win = 0, tlen;
106: struct route *ro = 0;
107:
108: if (tp) {
109: win = sbspace(&tp->t_inpcb->inp_socket->so_rcv);
110: ro = &tp->t_inpcb->inp_route;
111: }
112: if (flags == 0) {
113: m = m_get(M_DONTWAIT, MT_HEADER);
114: MBUFNULL(15, m); /* for debugging */
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: tlen = 1;
122: } else {
123: m = dtom(ti);
124: m_freem(m->m_next);
125: m->m_next = 0;
126: m->m_off = (int)ti - (int)m;
127: m->m_len = sizeof (struct tcpiphdr);
128: #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
129: xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long);
130: xchg(ti->ti_dport, ti->ti_sport, u_short);
131: #undef xchg
132: tlen = 0;
133: }
134: ti->ti_next = ti->ti_prev = 0;
135: ti->ti_x1 = 0;
136: ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
137: ti->ti_seq = htonl(seq);
138: ti->ti_ack = htonl(ack);
139: ti->ti_x2 = 0;
140: ti->ti_off = sizeof (struct tcphdr) >> 2;
141: ti->ti_flags = flags;
142: ti->ti_win = htons((u_short)win);
143: ti->ti_urp = 0;
144: ti->ti_sum = in_cksum(m, sizeof (struct tcpiphdr) + tlen);
145: ((struct ip *)ti)->ip_len = sizeof (struct tcpiphdr) + tlen;
146: ((struct ip *)ti)->ip_ttl = TCP_TTL;
147: (void) ip_output(m, (struct mbuf *)0, ro, 0);
148: }
149:
150: /*
151: * Create a new TCP control block, making an
152: * empty reassembly queue and hooking it to the argument
153: * protocol control block.
154: */
155: struct tcpcb *
156: tcp_newtcpcb(inp)
157: struct inpcb *inp;
158: {
159: struct mbuf *m = m_getclr(M_DONTWAIT, MT_PCB);
160: register struct tcpcb *tp;
161: struct ifnet *ifp;
162: struct ifnet *tcp_getif();
163: u_short ifmss;
164:
165: MBUFNULL(16, m); /* for debugging */
166: if (m == NULL)
167: return ((struct tcpcb *)0);
168: tp = mtod(m, struct tcpcb *);
169: tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp;
170: /*
171: * If the default maximum IP packet size is 576 bytes
172: * and a standard IP header is 20 bytes, with a TCP
173: * header of 20 bytes plus the options necessary to
174: * upgrade it to something higher, then initialize the
175: * maximum segment size to 576 - (20 + 20 + 8 + slop).
176: */
177: tp->t_maxseg = 512; /* satisfy the rest of the world */
178: tp->t_flags = 0; /* sends options! */
179: tp->t_inpcb = inp;
180: inp->inp_ppcb = (caddr_t)tp;
181: return (tp);
182: }
183:
184: /*
185: * Drop a TCP connection, reporting
186: * the specified error. If connection is synchronized,
187: * then send a RST to peer.
188: */
189: struct tcpcb *
190: tcp_drop(tp, errno)
191: register struct tcpcb *tp;
192: int errno;
193: {
194: struct socket *so = tp->t_inpcb->inp_socket;
195:
196: if (TCPS_HAVERCVDSYN(tp->t_state)) {
197: tp->t_state = TCPS_CLOSED;
198: (void) tcp_output(tp);
199: }
200: so->so_error = errno;
201: return (tcp_close(tp));
202: }
203:
204: tcp_abort(inp)
205: struct inpcb *inp;
206: {
207: #ifdef NET_PERF
208: printf("tcp_abort(local addr:%lx,%x, remote addr:%lx,%x)\n",
209: inp->inp_faddr.s_addr, inp->inp_fport,
210: inp->inp_laddr.s_addr, inp->inp_lport);
211: #endif
212:
213: (void) tcp_close((struct tcpcb *)inp->inp_ppcb);
214: }
215:
216: /*
217: * Close a TCP control block:
218: * discard all space held by the tcp
219: * discard internet protocol block
220: * wake up any sleepers
221: */
222: struct tcpcb *
223: tcp_close(tp)
224: register struct tcpcb *tp;
225: {
226: register struct tcpiphdr *t;
227: struct inpcb *inp = tp->t_inpcb;
228: struct socket *so = inp->inp_socket;
229: register struct mbuf *m;
230:
231: t = tp->seg_next;
232: while (t != (struct tcpiphdr *)tp) {
233: t = (struct tcpiphdr *)t->ti_next;
234: m = dtom(t->ti_prev);
235: remque(t->ti_prev);
236: m_freem(m);
237: }
238: if (tp->t_template)
239: (void) m_free(dtom(tp->t_template));
240: if (tp->t_tcpopt)
241: (void) m_free(dtom(tp->t_tcpopt));
242: if (tp->t_ipopt)
243: (void) m_free(dtom(tp->t_ipopt));
244: (void) m_free(dtom(tp));
245: inp->inp_ppcb = 0;
246: soisdisconnected(so);
247: in_pcbdetach(inp);
248: return ((struct tcpcb *)0);
249: }
250:
251: tcp_drain()
252: {
253:
254: }
255:
256: tcp_ctlinput(cmd, arg)
257: int cmd;
258: caddr_t arg;
259: {
260: struct in_addr *sin;
261: extern u_char inetctlerrmap[];
262:
263: if (cmd < 0 || cmd > PRC_NCMDS)
264: return;
265: switch (cmd) {
266:
267: case PRC_ROUTEDEAD:
268: break;
269:
270: case PRC_QUENCH:
271: break;
272:
273: /* these are handled by ip */
274: case PRC_IFDOWN:
275: case PRC_HOSTDEAD:
276: case PRC_HOSTUNREACH:
277: break;
278:
279: default:
280: sin = &((struct icmp *)arg)->icmp_ip.ip_dst;
281: in_pcbnotify(&tcb, sin, (int)inetctlerrmap[cmd], tcp_abort);
282: }
283: }
284: /*
285: * Given a tcpcb, find the route associated with tcpcb, then the
286: * interface through which packets are sent.
287: */
288: struct ifnet *
289: tcp_getif(tp)
290: struct tcpcb *tp;
291: {
292: register struct route *ro;
293: register struct ifnet *ifp;
294: struct route iproute;
295: struct in_addr faddr;
296:
297: ro = &iproute;
298: bzero((caddr_t)ro, sizeof(*ro));
299: ro->ro_dst.sa_family = AF_INET;
300: faddr = tp->t_inpcb->inp_faddr;
301: if (faddr.s_addr == 0)
302: return((struct ifnet *)0);
303:
304: ((struct sockaddr_in *) &iproute.ro_dst)->sin_addr = faddr;
305: rtalloc(ro);
306: if ((ro->ro_rt == 0) || (ifp = ro->ro_rt->rt_ifp) == 0)
307: return((struct ifnet *)0);
308: rtfree(ro->ro_rt);
309: return (ifp);
310: }
311:
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