[unix-history] / usr / src / sys / netinet / tcp_usrreq.c

/* tcp_usrreq.c 1.49 82/01/18 */

#include "../h/param.h"
#include "../h/systm.h"
#include "../h/mbuf.h"
#include "../h/socket.h"
#include "../h/socketvar.h"
#include "../h/protosw.h"
#include "../net/in.h"
#include "../net/in_pcb.h"
#include "../net/in_systm.h"
#include "../net/if.h"
#include "../net/ip.h"
#include "../net/ip_var.h"
#include "../net/tcp.h"
#include "../net/tcp_fsm.h"
#include "../net/tcp_seq.h"
#include "../net/tcp_timer.h"
#include "../net/tcp_var.h"
#include "../net/tcpip.h"
#include "../net/tcp_debug.h"
#include "../errno.h"

/*
 * TCP protocol interface to socket abstraction.
 */
extern	char *tcpstates[];
struct	tcpcb *tcp_newtcpcb();

/*
 * Process a TCP user request for TCP tb.  If this is a send request
 * then m is the mbuf chain of send data.  If this is a timer expiration
 * (called from the software clock routine), then timertype tells which timer.
 */
tcp_usrreq(so, req, m, addr)
	struct socket *so;
	int req;
	struct mbuf *m;
	caddr_t addr;
{
	register struct inpcb *inp = sotoinpcb(so);
	register struct tcpcb *tp;
	int s = splnet();
	int error = 0;
	int ostate;
COUNT(TCP_USRREQ);

	/*
	 * When a TCP is attached to a socket, then there will be
	 * a (struct inpcb) pointed at by the socket, and this
	 * structure will point at a subsidary (struct tcpcb).
	 * The normal sequence of events is:
	 *	PRU_ATTACH		creating these structures
	 *	PRU_CONNECT		connecting to a remote peer
	 *	(PRU_SEND|PRU_RCVD)*	exchanging data
	 *	PRU_DISCONNECT		disconnecting from remote peer
	 *	PRU_DETACH		deleting the structures
	 * With the operations from PRU_CONNECT through PRU_DISCONNECT
	 * possible repeated several times.
	 *
	 * MULTIPLE CONNECTS ARE NOT YET IMPLEMENTED.
	 */
	if (inp == 0 && req != PRU_ATTACH) {
		splx(s);
		return (EINVAL);		/* XXX */
	}
	if (inp) {
		tp = intotcpcb(inp);
#ifdef KPROF
		tcp_acounts[tp->t_state][req]++;
#endif
		ostate = tp->t_state;
	}
	switch (req) {

	/*
	 * TCP attaches to socket via PRU_ATTACH, reserving space,
	 * and internet and TCP control blocks.
	 * If the socket is to receive connections,
	 * then the LISTEN state is entered.
	 */
	case PRU_ATTACH:
		if (inp) {
			error = EISCONN;
			break;
		}
		error = tcp_attach(so, (struct sockaddr *)addr);
		if (error)
			break;
		if ((so->so_options & SO_DONTLINGER) == 0)
			so->so_linger = TCP_LINGERTIME;
		tp = sototcpcb(so);
		break;

	/*
	 * PRU_DETACH detaches the TCP protocol from the socket.
	 * If the protocol state is non-embryonic, then can't
	 * do this directly: have to initiate a PRU_DISCONNECT,
	 * which may finish later; embryonic TCB's can just
	 * be discarded here.
	 */
	case PRU_DETACH:
		if (tp->t_state > TCPS_LISTEN)
			tcp_disconnect(tp);
		else {
			tcp_close(tp);
			tp = 0;
		}
		break;

	/*
	 * Initiate connection to peer.
	 * Create a template for use in transmissions on this connection.
	 * Enter SYN_SENT state, and mark socket as connecting.
	 * Start keep-alive timer, and seed output sequence space.
	 * Send initial segment on connection.
	 */
	case PRU_CONNECT:
		error = in_pcbconnect(inp, (struct sockaddr_in *)addr);
		if (error)
			break;
		tp->t_template = tcp_template(tp);
		if (tp->t_template == 0) {
			in_pcbdisconnect(inp);
			error = ENOBUFS;
			break;
		}
		soisconnecting(so);
		tp->t_state = TCPS_SYN_SENT;
		tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
		tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2;
		tcp_sendseqinit(tp);
		(void) tcp_output(tp);
		break;

	/*
	 * Initiate disconnect from peer.
	 * If connection never passed embryonic stage, just drop;
	 * else if don't need to let data drain, then can just drop anyways,
	 * else have to begin TCP shutdown process: mark socket disconnecting,
	 * drain unread data, state switch to reflect user close, and
	 * send segment (e.g. FIN) to peer.  Socket will be really disconnected
	 * when peer sends FIN and acks ours.
	 *
	 * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB.
	 */
	case PRU_DISCONNECT:
		tcp_disconnect(tp);
		break;

	/*
	 * Accept a connection.  Essentially all the work is
	 * done at higher levels; just return the address
	 * of the peer, storing through addr.
	 */
	case PRU_ACCEPT:
		in_pcbconnaddr(inp, (struct sockaddr *)addr);
		break;

	/*
	 * Mark the connection as being incapable of further output.
	 */
	case PRU_SHUTDOWN:
		socantsendmore(so);
		tcp_usrclosed(tp);
		(void) tcp_output(tp);
		break;

	/*
	 * After a receive, possibly send window update to peer.
	 */
	case PRU_RCVD:
		(void) tcp_output(tp);
		break;

	/*
	 * Do a send by putting data in output queue and updating urgent
	 * marker if URG set.  Possibly send more data.
	 */
	case PRU_SEND:
		sbappend(&so->so_snd, m);
/*
		if (tp->t_flags & TF_PUSH)
			tp->snd_end = tp->snd_una + so->so_snd.sb_cc;
 */
		(void) tcp_output(tp);
		break;

	/*
	 * Abort the TCP.
	 */
	case PRU_ABORT:
		tcp_drop(tp, ECONNABORTED);
		break;

/* SOME AS YET UNIMPLEMENTED HOOKS */
	case PRU_CONTROL:
		error = EOPNOTSUPP;
		break;

	case PRU_SENSE:
		error = EOPNOTSUPP;
		break;
/* END UNIMPLEMENTED HOOKS */

	case PRU_RCVOOB:
		if (so->so_oobmark == 0 &&
		    (so->so_state & SS_RCVATMARK) == 0) {
			error = EINVAL;
			break;
		}
		if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) {
			error = EWOULDBLOCK;
			break;
		}
		*mtod(m, caddr_t) = tp->t_iobc;
		break;

	case PRU_SENDOOB:
#ifdef TCPTRUEOOB
		if (tp->t_flags & TF_DOOOB) {
			tp->t_oobseq++;
			tp->t_oobc = *mtod(m, caddr_t);
			tp->t_oobmark = tp->snd_una + so->so_snd.sb_cc;
printf("sendoob seq now %x oobc %x\n", tp->t_oobseq, tp->t_oobc);
			tp->t_oobflags |= TCPOOB_NEEDACK;
			(void) tcp_output(tp);
		}
#endif
		if (sbspace(&so->so_snd) < -512) {
			error = ENOBUFS;
			break;
		}
		tp->snd_up = tp->snd_una + so->so_snd.sb_cc + 1;
		sbappend(&so->so_snd, m);
/*
		if (tp->t_flags & TF_PUSH)
			tp->snd_end = tp->snd_una + so->so_snd.sb_cc;
 */
		tp->t_force = 1;
		(void) tcp_output(tp);
		tp->t_force = 0;
		break;

	/*
	 * TCP slow timer went off; going through this
	 * routine for tracing's sake.
	 */
	case PRU_SLOWTIMO:
		tcp_timers(tp, (int)addr);
		req |= (int)addr << 8;		/* for debug's sake */
		break;

	default:
		panic("tcp_usrreq");
	}
	if (tp && (so->so_options & SO_DEBUG))
		tcp_trace(TA_USER, ostate, tp, (struct tcpiphdr *)0, req);
	splx(s);
	return (error);
}

/*
 * Attach TCP protocol to socket, allocating
 * internet protocol control block, tcp control block,
 * bufer space, and entering LISTEN state if to accept connections.
 */
tcp_attach(so, sa)
	struct socket *so;
	struct sockaddr *sa;
{
	register struct tcpcb *tp;
	struct inpcb *inp;
	int error;

	error = in_pcbattach(so, &tcb, 2048, 2048, (struct sockaddr_in *)sa);
	if (error)
		return (error);
	inp = (struct inpcb *)so->so_pcb;
	tp = tcp_newtcpcb(inp);
	if (so->so_options & SO_ACCEPTCONN) {
		if (tp == 0) {
			in_pcbdetach(inp);
			return (ENOBUFS);
		}
		tp->t_state = TCPS_LISTEN;
	} else
		tp->t_state = TCPS_CLOSED;
	return (0);
}

/*
 * Initiate (or continue) disconnect.
 * If embryonic state, just send reset (once).
 * If not in ``let data drain'' option, just drop.
 * Otherwise (hard), mark socket disconnecting and drop
 * current input data; switch states based on user close, and
 * send segment to peer (with FIN).
 */
tcp_disconnect(tp)
	struct tcpcb *tp;
{
	struct socket *so = tp->t_inpcb->inp_socket;

	if (tp->t_state < TCPS_ESTABLISHED)
		tcp_close(tp);
	else if (so->so_linger == 0)
		tcp_drop(tp, 0);
	else {
		soisdisconnecting(so);
		sbflush(&so->so_rcv);
		tcp_usrclosed(tp);
		(void) tcp_output(tp);
	}
}

/*
 * User issued close, and wish to trail through shutdown states:
 * if never received SYN, just forget it.  If got a SYN from peer,
 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 * If already got a FIN from peer, then almost done; go to LAST_ACK
 * state.  In all other cases, have already sent FIN to peer (e.g.
 * after PRU_SHUTDOWN), and just have to play tedious game waiting
 * for peer to send FIN or not respond to keep-alives, etc.
 */
tcp_usrclosed(tp)
	struct tcpcb *tp;
{

	switch (tp->t_state) {

	case TCPS_LISTEN:
	case TCPS_SYN_SENT:
		tp->t_state = TCPS_CLOSED;
		tcp_close(tp);
		break;

	case TCPS_SYN_RECEIVED:
	case TCPS_ESTABLISHED:
		tp->t_state = TCPS_FIN_WAIT_1;
		break;

	case TCPS_CLOSE_WAIT:
		tp->t_state = TCPS_LAST_ACK;
		break;
	}
}
Commit	Line	Data
b2db9217	1	/* tcp_usrreq.c 1.49 82/01/18 */
72f24d7d	2
4eb5d593	3	#include "../h/param.h"
72f24d7d	4	#include "../h/systm.h"
dad64fdf BJ	5	#include "../h/mbuf.h"
dad64fdf BJ	6	#include "../h/socket.h"
eee3ab16 BJ	7	#include "../h/socketvar.h"
eee3ab16 BJ	8	#include "../h/protosw.h"
0974b45c BJ	9	#include "../net/in.h"
	10	#include "../net/in_pcb.h"
	11	#include "../net/in_systm.h"
4ad99bae	12	#include "../net/if.h"
eee3ab16	13	#include "../net/ip.h"
eb44bfb2	14	#include "../net/ip_var.h"
eee3ab16	15	#include "../net/tcp.h"
eee3ab16	16	#include "../net/tcp_fsm.h"
0974b45c BJ	17	#include "../net/tcp_seq.h"
0974b45c BJ	18	#include "../net/tcp_timer.h"
eee3ab16	19	#include "../net/tcp_var.h"
0974b45c	20	#include "../net/tcpip.h"
17b82ed4	21	#include "../net/tcp_debug.h"
f1b2fa5b	22	#include "../errno.h"
eee3ab16	23
290e0b0a BJ	24	/*
	25	* TCP protocol interface to socket abstraction.
	26	*/
	27	extern char *tcpstates[];
4ad99bae	28	struct tcpcb *tcp_newtcpcb();
290e0b0a	29
9c5022e3	30	/*
290e0b0a	31	* Process a TCP user request for TCP tb. If this is a send request
9c5022e3 BJ	32	* then m is the mbuf chain of send data. If this is a timer expiration
	33	* (called from the software clock routine), then timertype tells which timer.
	34	*/
eee3ab16 BJ	35	tcp_usrreq(so, req, m, addr)
	36	struct socket *so;
	37	int req;
9c5022e3	38	struct mbuf *m;
eee3ab16	39	caddr_t addr;
4eb5d593	40	{
53a5409e	41	register struct inpcb *inp = sotoinpcb(so);
cdad2eb1	42	register struct tcpcb *tp;
72f24d7d	43	int s = splnet();
eee3ab16	44	int error = 0;
17b82ed4	45	int ostate;
72f24d7d BJ	46	COUNT(TCP_USRREQ);
72f24d7d BJ	47
53a5409e	48	/*
290e0b0a BJ	49	* When a TCP is attached to a socket, then there will be
	50	* a (struct inpcb) pointed at by the socket, and this
	51	* structure will point at a subsidary (struct tcpcb).
	52	* The normal sequence of events is:
	53	* PRU_ATTACH creating these structures
	54	* PRU_CONNECT connecting to a remote peer
	55	* (PRU_SEND\|PRU_RCVD)* exchanging data
	56	* PRU_DISCONNECT disconnecting from remote peer
	57	* PRU_DETACH deleting the structures
	58	* With the operations from PRU_CONNECT through PRU_DISCONNECT
	59	* possible repeated several times.
	60	*
	61	* MULTIPLE CONNECTS ARE NOT YET IMPLEMENTED.
53a5409e	62	*/
0974b45c	63	if (inp == 0 && req != PRU_ATTACH) {
a6503abf	64	splx(s);
290e0b0a	65	return (EINVAL); /* XXX */
a6503abf BJ	66	}
a6503abf BJ	67	if (inp) {
cdad2eb1	68	tp = intotcpcb(inp);
9c5022e3	69	#ifdef KPROF
a6503abf	70	tcp_acounts[tp->t_state][req]++;
9c5022e3	71	#endif
17b82ed4	72	ostate = tp->t_state;
cdad2eb1	73	}
eee3ab16	74	switch (req) {
4eb5d593	75
290e0b0a BJ	76	/*
	77	* TCP attaches to socket via PRU_ATTACH, reserving space,
	78	* and internet and TCP control blocks.
	79	* If the socket is to receive connections,
	80	* then the LISTEN state is entered.
	81	*/
eee3ab16	82	case PRU_ATTACH:
4ad99bae	83	if (inp) {
eee3ab16	84	error = EISCONN;
cdad2eb1	85	break;
53a5409e	86	}
290e0b0a	87	error = tcp_attach(so, (struct sockaddr *)addr);
a6503abf	88	if (error)
4ad99bae	89	break;
8e65fd66 BJ	90	if ((so->so_options & SO_DONTLINGER) == 0)
8e65fd66 BJ	91	so->so_linger = TCP_LINGERTIME;
290e0b0a	92	tp = sototcpcb(so);
72f24d7d	93	break;
4eb5d593	94
290e0b0a BJ	95	/*
	96	* PRU_DETACH detaches the TCP protocol from the socket.
	97	* If the protocol state is non-embryonic, then can't
	98	* do this directly: have to initiate a PRU_DISCONNECT,
	99	* which may finish later; embryonic TCB's can just
	100	* be discarded here.
	101	*/
eee3ab16	102	case PRU_DETACH:
290e0b0a BJ	103	if (tp->t_state > TCPS_LISTEN)
	104	tcp_disconnect(tp);
	105	else {
	106	tcp_close(tp);
	107	tp = 0;
	108	}
eee3ab16 BJ	109	break;
eee3ab16 BJ	110
290e0b0a BJ	111	/*
	112	* Initiate connection to peer.
	113	* Create a template for use in transmissions on this connection.
	114	* Enter SYN_SENT state, and mark socket as connecting.
	115	* Start keep-alive timer, and seed output sequence space.
	116	* Send initial segment on connection.
	117	*/
eee3ab16	118	case PRU_CONNECT:
405c9168	119	error = in_pcbconnect(inp, (struct sockaddr_in *)addr);
4ad99bae	120	if (error)
53a5409e	121	break;
b454c3ea	122	tp->t_template = tcp_template(tp);
290e0b0a BJ	123	if (tp->t_template == 0) {
	124	in_pcbdisconnect(inp);
	125	error = ENOBUFS;
	126	break;
	127	}
53a5409e	128	soisconnecting(so);
a6503abf	129	tp->t_state = TCPS_SYN_SENT;
4aed14e3 BJ	130	tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
	131	tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2;
	132	tcp_sendseqinit(tp);
f1b2fa5b	133	(void) tcp_output(tp);
72f24d7d	134	break;
4eb5d593	135
290e0b0a BJ	136	/*
	137	* Initiate disconnect from peer.
	138	* If connection never passed embryonic stage, just drop;
	139	* else if don't need to let data drain, then can just drop anyways,
	140	* else have to begin TCP shutdown process: mark socket disconnecting,
	141	* drain unread data, state switch to reflect user close, and
	142	* send segment (e.g. FIN) to peer. Socket will be really disconnected
	143	* when peer sends FIN and acks ours.
	144	*
	145	* SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB.
	146	*/
	147	case PRU_DISCONNECT:
	148	tcp_disconnect(tp);
4aed14e3 BJ	149	break;
4aed14e3 BJ	150
290e0b0a BJ	151	/*
	152	* Accept a connection. Essentially all the work is
	153	* done at higher levels; just return the address
	154	* of the peer, storing through addr.
	155	*/
2b4b57cd	156	case PRU_ACCEPT:
290e0b0a	157	in_pcbconnaddr(inp, (struct sockaddr *)addr);
eee3ab16 BJ	158	break;
eee3ab16 BJ	159
290e0b0a BJ	160	/*
	161	* Mark the connection as being incapable of further output.
	162	*/
eee3ab16	163	case PRU_SHUTDOWN:
0974b45c	164	socantsendmore(so);
4aed14e3 BJ	165	tcp_usrclosed(tp);
4aed14e3 BJ	166	(void) tcp_output(tp);
72f24d7d BJ	167	break;
72f24d7d BJ	168
290e0b0a BJ	169	/*
	170	* After a receive, possibly send window update to peer.
	171	*/
eee3ab16	172	case PRU_RCVD:
f1b2fa5b	173	(void) tcp_output(tp);
72f24d7d BJ	174	break;
72f24d7d BJ	175
290e0b0a BJ	176	/*
	177	* Do a send by putting data in output queue and updating urgent
	178	* marker if URG set. Possibly send more data.
	179	*/
eee3ab16	180	case PRU_SEND:
a6503abf	181	sbappend(&so->so_snd, m);
0974b45c BJ	182	/*
0974b45c BJ	183	if (tp->t_flags & TF_PUSH)
a6503abf	184	tp->snd_end = tp->snd_una + so->so_snd.sb_cc;
0974b45c	185	*/
f1b2fa5b	186	(void) tcp_output(tp);
72f24d7d BJ	187	break;
72f24d7d BJ	188
290e0b0a BJ	189	/*
	190	* Abort the TCP.
	191	*/
eee3ab16	192	case PRU_ABORT:
a6503abf	193	tcp_drop(tp, ECONNABORTED);
72f24d7d BJ	194	break;
72f24d7d BJ	195
290e0b0a	196	/* SOME AS YET UNIMPLEMENTED HOOKS */
eee3ab16	197	case PRU_CONTROL:
53a5409e	198	error = EOPNOTSUPP;
eee3ab16 BJ	199	break;
eee3ab16 BJ	200
f1b2fa5b BJ	201	case PRU_SENSE:
	202	error = EOPNOTSUPP;
	203	break;
0244dbc7	204	/* END UNIMPLEMENTED HOOKS */
f1b2fa5b BJ	205
f1b2fa5b BJ	206	case PRU_RCVOOB:
8b5a83bb BJ	207	if (so->so_oobmark == 0 &&
8b5a83bb BJ	208	(so->so_state & SS_RCVATMARK) == 0) {
0244dbc7 BJ	209	error = EINVAL;
	210	break;
	211	}
b2db9217	212	if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) {
8b5a83bb	213	error = EWOULDBLOCK;
b2db9217	214	break;
8b5a83bb	215	}
b2db9217	216	*mtod(m, caddr_t) = tp->t_iobc;
f1b2fa5b BJ	217	break;
	218
	219	case PRU_SENDOOB:
b2db9217 BJ	220	#ifdef TCPTRUEOOB
	221	if (tp->t_flags & TF_DOOOB) {
	222	tp->t_oobseq++;
	223	tp->t_oobc = *mtod(m, caddr_t);
	224	tp->t_oobmark = tp->snd_una + so->so_snd.sb_cc;
	225	printf("sendoob seq now %x oobc %x\n", tp->t_oobseq, tp->t_oobc);
	226	tp->t_oobflags \|= TCPOOB_NEEDACK;
	227	(void) tcp_output(tp);
	228	}
	229	#endif
8b5a83bb BJ	230	if (sbspace(&so->so_snd) < -512) {
	231	error = ENOBUFS;
	232	break;
	233	}
0244dbc7 BJ	234	tp->snd_up = tp->snd_una + so->so_snd.sb_cc + 1;
	235	sbappend(&so->so_snd, m);
	236	/*
	237	if (tp->t_flags & TF_PUSH)
	238	tp->snd_end = tp->snd_una + so->so_snd.sb_cc;
	239	*/
b2db9217 BJ	240	tp->t_force = 1;
	241	(void) tcp_output(tp);
	242	tp->t_force = 0;
f1b2fa5b BJ	243	break;
f1b2fa5b BJ	244
290e0b0a BJ	245	/*
	246	* TCP slow timer went off; going through this
	247	* routine for tracing's sake.
	248	*/
eee3ab16	249	case PRU_SLOWTIMO:
a6503abf	250	tcp_timers(tp, (int)addr);
17b82ed4	251	req \|= (int)addr << 8; /* for debug's sake */
eee3ab16 BJ	252	break;
eee3ab16 BJ	253
9c5022e3 BJ	254	default:
9c5022e3 BJ	255	panic("tcp_usrreq");
72f24d7d	256	}
17b82ed4 BJ	257	if (tp && (so->so_options & SO_DEBUG))
17b82ed4 BJ	258	tcp_trace(TA_USER, ostate, tp, (struct tcpiphdr *)0, req);
72f24d7d	259	splx(s);
53a5409e	260	return (error);
4eb5d593	261	}
4aed14e3	262
290e0b0a BJ	263	/*
	264	* Attach TCP protocol to socket, allocating
	265	* internet protocol control block, tcp control block,
	266	* bufer space, and entering LISTEN state if to accept connections.
	267	*/
	268	tcp_attach(so, sa)
	269	struct socket *so;
	270	struct sockaddr *sa;
	271	{
	272	register struct tcpcb *tp;
	273	struct inpcb *inp;
	274	int error;
	275
	276	error = in_pcbattach(so, &tcb, 2048, 2048, (struct sockaddr_in *)sa);
	277	if (error)
	278	return (error);
	279	inp = (struct inpcb *)so->so_pcb;
	280	tp = tcp_newtcpcb(inp);
	281	if (so->so_options & SO_ACCEPTCONN) {
	282	if (tp == 0) {
	283	in_pcbdetach(inp);
	284	return (ENOBUFS);
	285	}
	286	tp->t_state = TCPS_LISTEN;
	287	} else
	288	tp->t_state = TCPS_CLOSED;
	289	return (0);
	290	}
	291
	292	/*
	293	* Initiate (or continue) disconnect.
	294	* If embryonic state, just send reset (once).
	295	* If not in ``let data drain'' option, just drop.
	296	* Otherwise (hard), mark socket disconnecting and drop
	297	* current input data; switch states based on user close, and
	298	* send segment to peer (with FIN).
	299	*/
	300	tcp_disconnect(tp)
	301	struct tcpcb *tp;
	302	{
	303	struct socket *so = tp->t_inpcb->inp_socket;
	304
	305	if (tp->t_state < TCPS_ESTABLISHED)
	306	tcp_close(tp);
8e65fd66	307	else if (so->so_linger == 0)
290e0b0a BJ	308	tcp_drop(tp, 0);
	309	else {
	310	soisdisconnecting(so);
	311	sbflush(&so->so_rcv);
	312	tcp_usrclosed(tp);
	313	(void) tcp_output(tp);
	314	}
	315	}
	316
	317	/*
	318	* User issued close, and wish to trail through shutdown states:
	319	* if never received SYN, just forget it. If got a SYN from peer,
	320	* but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
	321	* If already got a FIN from peer, then almost done; go to LAST_ACK
	322	* state. In all other cases, have already sent FIN to peer (e.g.
	323	* after PRU_SHUTDOWN), and just have to play tedious game waiting
	324	* for peer to send FIN or not respond to keep-alives, etc.
	325	*/
4aed14e3 BJ	326	tcp_usrclosed(tp)
	327	struct tcpcb *tp;
	328	{
	329
4aed14e3 BJ	330	switch (tp->t_state) {
	331
	332	case TCPS_LISTEN:
	333	case TCPS_SYN_SENT:
	334	tp->t_state = TCPS_CLOSED;
	335	tcp_close(tp);
	336	break;
	337
	338	case TCPS_SYN_RECEIVED:
	339	case TCPS_ESTABLISHED:
	340	tp->t_state = TCPS_FIN_WAIT_1;
	341	break;
	342
	343	case TCPS_CLOSE_WAIT:
	344	tp->t_state = TCPS_LAST_ACK;
	345	break;
	346	}
4aed14e3	347	}