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tcp_usrreq.c revision 1.8
      1 /*
      2  * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  *
     33  *	from: @(#)tcp_usrreq.c	7.15 (Berkeley) 6/28/90
     34  *	$Id: tcp_usrreq.c,v 1.8 1994/01/10 23:27:45 mycroft Exp $
     35  */
     36 
     37 #include <sys/param.h>
     38 #include <sys/systm.h>
     39 #include <sys/malloc.h>
     40 #include <sys/mbuf.h>
     41 #include <sys/socket.h>
     42 #include <sys/socketvar.h>
     43 #include <sys/protosw.h>
     44 #include <sys/errno.h>
     45 #include <sys/stat.h>
     46 
     47 #include <net/if.h>
     48 #include <net/route.h>
     49 
     50 #include <netinet/in.h>
     51 #include <netinet/in_systm.h>
     52 #include <netinet/ip.h>
     53 #include <netinet/in_pcb.h>
     54 #include <netinet/ip_var.h>
     55 #include <netinet/tcp.h>
     56 #include <netinet/tcp_fsm.h>
     57 #include <netinet/tcp_seq.h>
     58 #include <netinet/tcp_timer.h>
     59 #include <netinet/tcp_var.h>
     60 #include <netinet/tcpip.h>
     61 #include <netinet/tcp_debug.h>
     62 
     63 /*
     64  * TCP protocol interface to socket abstraction.
     65  */
     66 extern	char *tcpstates[];
     67 
     68 /*
     69  * Process a TCP user request for TCP tb.  If this is a send request
     70  * then m is the mbuf chain of send data.  If this is a timer expiration
     71  * (called from the software clock routine), then timertype tells which timer.
     72  */
     73 /*ARGSUSED*/
     74 int
     75 tcp_usrreq(so, req, m, nam, control)
     76 	struct socket *so;
     77 	int req;
     78 	struct mbuf *m, *nam, *control;
     79 {
     80 	register struct inpcb *inp;
     81 	register struct tcpcb *tp;
     82 	int s;
     83 	int error = 0;
     84 	int ostate;
     85 
     86 	if (req == PRU_CONTROL)
     87 		return (in_control(so, (int)m, (caddr_t)nam,
     88 			(struct ifnet *)control));
     89 	if (control && control->m_len) {
     90 		m_freem(control);
     91 		if (m)
     92 			m_freem(m);
     93 		return (EINVAL);
     94 	}
     95 
     96 	s = splnet();
     97 	inp = sotoinpcb(so);
     98 	/*
     99 	 * When a TCP is attached to a socket, then there will be
    100 	 * a (struct inpcb) pointed at by the socket, and this
    101 	 * structure will point at a subsidary (struct tcpcb).
    102 	 */
    103 	if (inp == 0 && req != PRU_ATTACH) {
    104 		splx(s);
    105 		return (EINVAL);		/* XXX */
    106 	}
    107 	if (inp) {
    108 		tp = intotcpcb(inp);
    109 		/* WHAT IF TP IS 0? */
    110 #ifdef KPROF
    111 		tcp_acounts[tp->t_state][req]++;
    112 #endif
    113 		ostate = tp->t_state;
    114 	} else
    115 		ostate = 0;
    116 	switch (req) {
    117 
    118 	/*
    119 	 * TCP attaches to socket via PRU_ATTACH, reserving space,
    120 	 * and an internet control block.
    121 	 */
    122 	case PRU_ATTACH:
    123 		if (inp) {
    124 			error = EISCONN;
    125 			break;
    126 		}
    127 		error = tcp_attach(so);
    128 		if (error)
    129 			break;
    130 		if ((so->so_options & SO_LINGER) && so->so_linger == 0)
    131 			so->so_linger = TCP_LINGERTIME;
    132 		tp = sototcpcb(so);
    133 		break;
    134 
    135 	/*
    136 	 * PRU_DETACH detaches the TCP protocol from the socket.
    137 	 * If the protocol state is non-embryonic, then can't
    138 	 * do this directly: have to initiate a PRU_DISCONNECT,
    139 	 * which may finish later; embryonic TCB's can just
    140 	 * be discarded here.
    141 	 */
    142 	case PRU_DETACH:
    143 		if (tp->t_state > TCPS_LISTEN)
    144 			tp = tcp_disconnect(tp);
    145 		else
    146 			tp = tcp_close(tp);
    147 		break;
    148 
    149 	/*
    150 	 * Give the socket an address.
    151 	 */
    152 	case PRU_BIND:
    153 		error = in_pcbbind(inp, nam);
    154 		if (error)
    155 			break;
    156 		break;
    157 
    158 	/*
    159 	 * Prepare to accept connections.
    160 	 */
    161 	case PRU_LISTEN:
    162 		if (inp->inp_lport == 0)
    163 			error = in_pcbbind(inp, (struct mbuf *)0);
    164 		if (error == 0)
    165 			tp->t_state = TCPS_LISTEN;
    166 		break;
    167 
    168 	/*
    169 	 * Initiate connection to peer.
    170 	 * Create a template for use in transmissions on this connection.
    171 	 * Enter SYN_SENT state, and mark socket as connecting.
    172 	 * Start keep-alive timer, and seed output sequence space.
    173 	 * Send initial segment on connection.
    174 	 */
    175 	case PRU_CONNECT:
    176 		if (inp->inp_lport == 0) {
    177 			error = in_pcbbind(inp, (struct mbuf *)0);
    178 			if (error)
    179 				break;
    180 		}
    181 		error = in_pcbconnect(inp, nam);
    182 		if (error)
    183 			break;
    184 		tp->t_template = tcp_template(tp);
    185 		if (tp->t_template == 0) {
    186 			in_pcbdisconnect(inp);
    187 			error = ENOBUFS;
    188 			break;
    189 		}
    190 		soisconnecting(so);
    191 		tcpstat.tcps_connattempt++;
    192 		tp->t_state = TCPS_SYN_SENT;
    193 		tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
    194 		tp->iss = tcp_iss; tcp_iss += TCP_ISSINCR/2;
    195 		tcp_sendseqinit(tp);
    196 		error = tcp_output(tp);
    197 		break;
    198 
    199 	/*
    200 	 * Create a TCP connection between two sockets.
    201 	 */
    202 	case PRU_CONNECT2:
    203 		error = EOPNOTSUPP;
    204 		break;
    205 
    206 	/*
    207 	 * Initiate disconnect from peer.
    208 	 * If connection never passed embryonic stage, just drop;
    209 	 * else if don't need to let data drain, then can just drop anyways,
    210 	 * else have to begin TCP shutdown process: mark socket disconnecting,
    211 	 * drain unread data, state switch to reflect user close, and
    212 	 * send segment (e.g. FIN) to peer.  Socket will be really disconnected
    213 	 * when peer sends FIN and acks ours.
    214 	 *
    215 	 * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB.
    216 	 */
    217 	case PRU_DISCONNECT:
    218 		tp = tcp_disconnect(tp);
    219 		break;
    220 
    221 	/*
    222 	 * Accept a connection.  Essentially all the work is
    223 	 * done at higher levels; just return the address
    224 	 * of the peer, storing through addr.
    225 	 */
    226 	case PRU_ACCEPT:
    227 		in_setpeeraddr(inp, nam);
    228 		break;
    229 
    230 	/*
    231 	 * Mark the connection as being incapable of further output.
    232 	 */
    233 	case PRU_SHUTDOWN:
    234 		socantsendmore(so);
    235 		tp = tcp_usrclosed(tp);
    236 		if (tp)
    237 			error = tcp_output(tp);
    238 		break;
    239 
    240 	/*
    241 	 * After a receive, possibly send window update to peer.
    242 	 */
    243 	case PRU_RCVD:
    244 		(void) tcp_output(tp);
    245 		break;
    246 
    247 	/*
    248 	 * Do a send by putting data in output queue and updating urgent
    249 	 * marker if URG set.  Possibly send more data.
    250 	 */
    251 	case PRU_SEND:
    252 		sbappend(&so->so_snd, m);
    253 		error = tcp_output(tp);
    254 		break;
    255 
    256 	/*
    257 	 * Abort the TCP.
    258 	 */
    259 	case PRU_ABORT:
    260 		tp = tcp_drop(tp, ECONNABORTED);
    261 		break;
    262 
    263 	case PRU_SENSE:
    264 		((struct stat *) m)->st_blksize = so->so_snd.sb_hiwat;
    265 		(void) splx(s);
    266 		return (0);
    267 
    268 	case PRU_RCVOOB:
    269 		if ((so->so_oobmark == 0 &&
    270 		    (so->so_state & SS_RCVATMARK) == 0) ||
    271 		    so->so_options & SO_OOBINLINE ||
    272 		    tp->t_oobflags & TCPOOB_HADDATA) {
    273 			error = EINVAL;
    274 			break;
    275 		}
    276 		if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) {
    277 			error = EWOULDBLOCK;
    278 			break;
    279 		}
    280 		m->m_len = 1;
    281 		*mtod(m, caddr_t) = tp->t_iobc;
    282 		if (((int)nam & MSG_PEEK) == 0)
    283 			tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA);
    284 		break;
    285 
    286 	case PRU_SENDOOB:
    287 		if (sbspace(&so->so_snd) < -512) {
    288 			m_freem(m);
    289 			error = ENOBUFS;
    290 			break;
    291 		}
    292 		/*
    293 		 * According to RFC961 (Assigned Protocols),
    294 		 * the urgent pointer points to the last octet
    295 		 * of urgent data.  We continue, however,
    296 		 * to consider it to indicate the first octet
    297 		 * of data past the urgent section.
    298 		 * Otherwise, snd_up should be one lower.
    299 		 */
    300 		sbappend(&so->so_snd, m);
    301 		tp->snd_up = tp->snd_una + so->so_snd.sb_cc;
    302 		tp->t_force = 1;
    303 		error = tcp_output(tp);
    304 		tp->t_force = 0;
    305 		break;
    306 
    307 	case PRU_SOCKADDR:
    308 		in_setsockaddr(inp, nam);
    309 		break;
    310 
    311 	case PRU_PEERADDR:
    312 		in_setpeeraddr(inp, nam);
    313 		break;
    314 
    315 	/*
    316 	 * TCP slow timer went off; going through this
    317 	 * routine for tracing's sake.
    318 	 */
    319 	case PRU_SLOWTIMO:
    320 		tp = tcp_timers(tp, (int)nam);
    321 		req |= (int)nam << 8;		/* for debug's sake */
    322 		break;
    323 
    324 	default:
    325 		panic("tcp_usrreq");
    326 	}
    327 	if (tp && (so->so_options & SO_DEBUG))
    328 		tcp_trace(TA_USER, ostate, tp, (struct tcpiphdr *)0, req);
    329 	splx(s);
    330 	return (error);
    331 }
    332 
    333 int
    334 tcp_ctloutput(op, so, level, optname, mp)
    335 	int op;
    336 	struct socket *so;
    337 	int level, optname;
    338 	struct mbuf **mp;
    339 {
    340 	int error = 0;
    341 	struct inpcb *inp = sotoinpcb(so);
    342 	register struct tcpcb *tp = intotcpcb(inp);
    343 	register struct mbuf *m;
    344 
    345 	if (level != IPPROTO_TCP)
    346 		return (ip_ctloutput(op, so, level, optname, mp));
    347 
    348 	switch (op) {
    349 
    350 	case PRCO_SETOPT:
    351 		m = *mp;
    352 		switch (optname) {
    353 
    354 		case TCP_NODELAY:
    355 			if (m == NULL || m->m_len < sizeof (int))
    356 				error = EINVAL;
    357 			else if (*mtod(m, int *))
    358 				tp->t_flags |= TF_NODELAY;
    359 			else
    360 				tp->t_flags &= ~TF_NODELAY;
    361 			break;
    362 
    363 		case TCP_MAXSEG:	/* not yet */
    364 		default:
    365 			error = EINVAL;
    366 			break;
    367 		}
    368 		if (m)
    369 			(void) m_free(m);
    370 		break;
    371 
    372 	case PRCO_GETOPT:
    373 		*mp = m = m_get(M_WAIT, MT_SOOPTS);
    374 		m->m_len = sizeof(int);
    375 
    376 		switch (optname) {
    377 		case TCP_NODELAY:
    378 			*mtod(m, int *) = tp->t_flags & TF_NODELAY;
    379 			break;
    380 		case TCP_MAXSEG:
    381 			*mtod(m, int *) = tp->t_maxseg;
    382 			break;
    383 		default:
    384 			error = EINVAL;
    385 			break;
    386 		}
    387 		break;
    388 	}
    389 	return (error);
    390 }
    391 
    392 u_long	tcp_sendspace = 1024*8;
    393 u_long	tcp_recvspace = 1024*8;
    394 
    395 /*
    396  * Attach TCP protocol to socket, allocating
    397  * internet protocol control block, tcp control block,
    398  * bufer space, and entering LISTEN state if to accept connections.
    399  */
    400 int
    401 tcp_attach(so)
    402 	struct socket *so;
    403 {
    404 	register struct tcpcb *tp;
    405 	struct inpcb *inp;
    406 	int error;
    407 
    408 	if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
    409 		error = soreserve(so, tcp_sendspace, tcp_recvspace);
    410 		if (error)
    411 			return (error);
    412 	}
    413 	error = in_pcballoc(so, &tcb);
    414 	if (error)
    415 		return (error);
    416 	inp = sotoinpcb(so);
    417 	tp = tcp_newtcpcb(inp);
    418 	if (tp == 0) {
    419 		int nofd = so->so_state & SS_NOFDREF;	/* XXX */
    420 
    421 		so->so_state &= ~SS_NOFDREF;	/* don't free the socket yet */
    422 		in_pcbdetach(inp);
    423 		so->so_state |= nofd;
    424 		return (ENOBUFS);
    425 	}
    426 	tp->t_state = TCPS_CLOSED;
    427 	return (0);
    428 }
    429 
    430 /*
    431  * Initiate (or continue) disconnect.
    432  * If embryonic state, just send reset (once).
    433  * If in ``let data drain'' option and linger null, just drop.
    434  * Otherwise (hard), mark socket disconnecting and drop
    435  * current input data; switch states based on user close, and
    436  * send segment to peer (with FIN).
    437  */
    438 struct tcpcb *
    439 tcp_disconnect(tp)
    440 	register struct tcpcb *tp;
    441 {
    442 	struct socket *so = tp->t_inpcb->inp_socket;
    443 
    444 	if (tp->t_state < TCPS_ESTABLISHED)
    445 		tp = tcp_close(tp);
    446 	else if ((so->so_options & SO_LINGER) && so->so_linger == 0)
    447 		tp = tcp_drop(tp, 0);
    448 	else {
    449 		soisdisconnecting(so);
    450 		sbflush(&so->so_rcv);
    451 		tp = tcp_usrclosed(tp);
    452 		if (tp)
    453 			(void) tcp_output(tp);
    454 	}
    455 	return (tp);
    456 }
    457 
    458 /*
    459  * User issued close, and wish to trail through shutdown states:
    460  * if never received SYN, just forget it.  If got a SYN from peer,
    461  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
    462  * If already got a FIN from peer, then almost done; go to LAST_ACK
    463  * state.  In all other cases, have already sent FIN to peer (e.g.
    464  * after PRU_SHUTDOWN), and just have to play tedious game waiting
    465  * for peer to send FIN or not respond to keep-alives, etc.
    466  * We can let the user exit from the close as soon as the FIN is acked.
    467  */
    468 struct tcpcb *
    469 tcp_usrclosed(tp)
    470 	register struct tcpcb *tp;
    471 {
    472 
    473 	switch (tp->t_state) {
    474 
    475 	case TCPS_CLOSED:
    476 	case TCPS_LISTEN:
    477 	case TCPS_SYN_SENT:
    478 		tp->t_state = TCPS_CLOSED;
    479 		tp = tcp_close(tp);
    480 		break;
    481 
    482 	case TCPS_SYN_RECEIVED:
    483 	case TCPS_ESTABLISHED:
    484 		tp->t_state = TCPS_FIN_WAIT_1;
    485 		break;
    486 
    487 	case TCPS_CLOSE_WAIT:
    488 		tp->t_state = TCPS_LAST_ACK;
    489 		break;
    490 	}
    491 	if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
    492 		soisdisconnected(tp->t_inpcb->inp_socket);
    493 	return (tp);
    494 }
    495