aboutsummaryrefslogtreecommitdiffstats
path: root/slirp/udp.c
blob: 11e78cddd5cf89b2c94e5fcda9d98c196c599451 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)udp_usrreq.c	8.4 (Berkeley) 1/21/94
 * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
 */

/*
 * Changes and additions relating to SLiRP
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#include <slirp.h>
#include "ip_icmp.h"

#ifdef LOG_ENABLED
struct udpstat udpstat;
#endif

struct socket udb;

static u_int8_t udp_tos(struct socket *so);
static void udp_emu(struct socket *so, struct mbuf *m);

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */
#ifndef	COMPAT_42
#define UDPCKSUM 1
#else
#define UDPCKSUM 0 /* XXX */
#endif

struct	socket *udp_last_so = &udb;

void
udp_init(void)
{
	udb.so_next = udb.so_prev = &udb;
}
/* m->m_data  points at ip packet header
 * m->m_len   length ip packet
 * ip->ip_len length data (IPDU)
 */
void
udp_input(register struct mbuf *m, int iphlen)
{
	register struct ip *ip;
	register struct udphdr *uh;
/*	struct mbuf *opts = 0;*/
	int len;
	struct ip save_ip;
	struct socket *so;

	DEBUG_CALL("udp_input");
	DEBUG_ARG("m = %lx", (long)m);
	DEBUG_ARG("iphlen = %d", iphlen);

	STAT(udpstat.udps_ipackets++);

	/*
	 * Strip IP options, if any; should skip this,
	 * make available to user, and use on returned packets,
	 * but we don't yet have a way to check the checksum
	 * with options still present.
	 */
	if(iphlen > sizeof(struct ip)) {
		ip_stripoptions(m, (struct mbuf *)0);
		iphlen = sizeof(struct ip);
	}

	/*
	 * Get IP and UDP header together in first mbuf.
	 */
	ip = mtod(m, struct ip *);
	uh = (struct udphdr *)((caddr_t)ip + iphlen);

	/*
	 * Make mbuf data length reflect UDP length.
	 * If not enough data to reflect UDP length, drop.
	 */
	len = ntohs((u_int16_t)uh->uh_ulen);

	if (ip->ip_len != len) {
		if (len > ip->ip_len) {
			STAT(udpstat.udps_badlen++);
			goto bad;
		}
		m_adj(m, len - ip->ip_len);
		ip->ip_len = len;
	}

	/*
	 * Save a copy of the IP header in case we want restore it
	 * for sending an ICMP error message in response.
	 */
	save_ip = *ip;
	save_ip.ip_len+= iphlen;         /* tcp_input subtracts this */

	/*
	 * Checksum extended UDP header and data.
	 */
	if (UDPCKSUM && uh->uh_sum) {
      memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
	  ((struct ipovly *)ip)->ih_x1 = 0;
	  ((struct ipovly *)ip)->ih_len = uh->uh_ulen;
	  /* keep uh_sum for ICMP reply
	   * uh->uh_sum = cksum(m, len + sizeof (struct ip));
	   * if (uh->uh_sum) {
	   */
	  if(cksum(m, len + sizeof(struct ip))) {
	    STAT(udpstat.udps_badsum++);
	    goto bad;
	  }
	}

        /*
         *  handle DHCP/BOOTP
         */
        if (ntohs(uh->uh_dport) == BOOTP_SERVER) {
            bootp_input(m);
            goto bad;
        }

        if (slirp_restrict)
            goto bad;

        /*
         *  handle TFTP
         */
        if (ntohs(uh->uh_dport) == TFTP_SERVER) {
            tftp_input(m);
            goto bad;
        }

	/*
	 * Locate pcb for datagram.
	 */
	so = udp_last_so;
	if (so->so_lport != uh->uh_sport ||
	    so->so_laddr.s_addr != ip->ip_src.s_addr) {
		struct socket *tmp;

		for (tmp = udb.so_next; tmp != &udb; tmp = tmp->so_next) {
			if (tmp->so_lport == uh->uh_sport &&
			    tmp->so_laddr.s_addr == ip->ip_src.s_addr) {
				tmp->so_faddr.s_addr = ip->ip_dst.s_addr;
				tmp->so_fport = uh->uh_dport;
				so = tmp;
				break;
			}
		}
		if (tmp == &udb) {
		  so = NULL;
		} else {
		  STAT(udpstat.udpps_pcbcachemiss++);
		  udp_last_so = so;
		}
	}

	if (so == NULL) {
	  /*
	   * If there's no socket for this packet,
	   * create one
	   */
	  if ((so = socreate()) == NULL) goto bad;
	  if(udp_attach(so) == -1) {
	    DEBUG_MISC((dfd," udp_attach errno = %d-%s\n",
			errno,strerror(errno)));
	    sofree(so);
	    goto bad;
	  }

	  /*
	   * Setup fields
	   */
	  /* udp_last_so = so; */
	  so->so_laddr = ip->ip_src;
	  so->so_lport = uh->uh_sport;

	  if ((so->so_iptos = udp_tos(so)) == 0)
	    so->so_iptos = ip->ip_tos;

	  /*
	   * XXXXX Here, check if it's in udpexec_list,
	   * and if it is, do the fork_exec() etc.
	   */
	}

        so->so_faddr = ip->ip_dst; /* XXX */
        so->so_fport = uh->uh_dport; /* XXX */

	iphlen += sizeof(struct udphdr);
	m->m_len -= iphlen;
	m->m_data += iphlen;

	/*
	 * Now we sendto() the packet.
	 */
	if (so->so_emu)
	   udp_emu(so, m);

	if(sosendto(so,m) == -1) {
	  m->m_len += iphlen;
	  m->m_data -= iphlen;
	  *ip=save_ip;
	  DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno)));
	  icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
	}

	m_free(so->so_m);   /* used for ICMP if error on sorecvfrom */

	/* restore the orig mbuf packet */
	m->m_len += iphlen;
	m->m_data -= iphlen;
	*ip=save_ip;
	so->so_m=m;         /* ICMP backup */

	return;
bad:
	m_freem(m);
	/* if (opts) m_freem(opts); */
	return;
}

int udp_output2(struct socket *so, struct mbuf *m,
                struct sockaddr_in *saddr, struct sockaddr_in *daddr,
                int iptos)
{
	register struct udpiphdr *ui;
	int error = 0;

	DEBUG_CALL("udp_output");
	DEBUG_ARG("so = %lx", (long)so);
	DEBUG_ARG("m = %lx", (long)m);
	DEBUG_ARG("saddr = %lx", (long)saddr->sin_addr.s_addr);
	DEBUG_ARG("daddr = %lx", (long)daddr->sin_addr.s_addr);

	/*
	 * Adjust for header
	 */
	m->m_data -= sizeof(struct udpiphdr);
	m->m_len += sizeof(struct udpiphdr);

	/*
	 * Fill in mbuf with extended UDP header
	 * and addresses and length put into network format.
	 */
	ui = mtod(m, struct udpiphdr *);
    memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
	ui->ui_x1 = 0;
	ui->ui_pr = IPPROTO_UDP;
	ui->ui_len = htons(m->m_len - sizeof(struct ip)); /* + sizeof (struct udphdr)); */
	/* XXXXX Check for from-one-location sockets, or from-any-location sockets */
        ui->ui_src = saddr->sin_addr;
	ui->ui_dst = daddr->sin_addr;
	ui->ui_sport = saddr->sin_port;
	ui->ui_dport = daddr->sin_port;
	ui->ui_ulen = ui->ui_len;

	/*
	 * Stuff checksum and output datagram.
	 */
	ui->ui_sum = 0;
	if (UDPCKSUM) {
	    if ((ui->ui_sum = cksum(m, /* sizeof (struct udpiphdr) + */ m->m_len)) == 0)
		ui->ui_sum = 0xffff;
	}
	((struct ip *)ui)->ip_len = m->m_len;

	((struct ip *)ui)->ip_ttl = IPDEFTTL;
	((struct ip *)ui)->ip_tos = iptos;

	STAT(udpstat.udps_opackets++);

	error = ip_output(so, m);

	return (error);
}

int udp_output(struct socket *so, struct mbuf *m,
               struct sockaddr_in *addr)

{
    struct sockaddr_in saddr, daddr;

    saddr = *addr;
    if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
        if ((so->so_faddr.s_addr & htonl(0x000000ff)) == htonl(0xff))
            saddr.sin_addr.s_addr = alias_addr.s_addr;
        else if (addr->sin_addr.s_addr == loopback_addr.s_addr ||
                 (ntohl(so->so_faddr.s_addr) & 0xff) != CTL_ALIAS)
            saddr.sin_addr.s_addr = so->so_faddr.s_addr;
    }
    daddr.sin_addr = so->so_laddr;
    daddr.sin_port = so->so_lport;

    return udp_output2(so, m, &saddr, &daddr, so->so_iptos);
}

int
udp_attach(struct socket *so)
{
  struct sockaddr_in addr;

  if((so->s = socket(AF_INET,SOCK_DGRAM,0)) != -1) {
    /*
     * Here, we bind() the socket.  Although not really needed
     * (sendto() on an unbound socket will bind it), it's done
     * here so that emulation of ytalk etc. don't have to do it
     */
    addr.sin_family = AF_INET;
    addr.sin_port = 0;
    addr.sin_addr.s_addr = INADDR_ANY;
    if(bind(so->s, (struct sockaddr *)&addr, sizeof(addr))<0) {
      int lasterrno=errno;
      closesocket(so->s);
      so->s=-1;
#ifdef _WIN32
      WSASetLastError(lasterrno);
#else
      errno=lasterrno;
#endif
    } else {
      /* success, insert in queue */
      so->so_expire = curtime + SO_EXPIRE;
      insque(so,&udb);
    }
  }
  return(so->s);
}

void
udp_detach(struct socket *so)
{
	closesocket(so->s);
	/* if (so->so_m) m_free(so->so_m);    done by sofree */

	sofree(so);
}

static const struct tos_t udptos[] = {
	{0, 53, IPTOS_LOWDELAY, 0},			/* DNS */
	{517, 517, IPTOS_LOWDELAY, EMU_TALK},	/* talk */
	{518, 518, IPTOS_LOWDELAY, EMU_NTALK},	/* ntalk */
	{0, 7648, IPTOS_LOWDELAY, EMU_CUSEEME},	/* Cu-Seeme */
	{0, 0, 0, 0}
};

static u_int8_t
udp_tos(struct socket *so)
{
	int i = 0;

	while(udptos[i].tos) {
		if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
		    (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
		    	so->so_emu = udptos[i].emu;
			return udptos[i].tos;
		}
		i++;
	}

	return 0;
}

#ifdef EMULATE_TALK
#include "talkd.h"
#endif

/*
 * Here, talk/ytalk/ntalk requests must be emulated
 */
static void
udp_emu(struct socket *so, struct mbuf *m)
{
	struct sockaddr_in addr;
	socklen_t addrlen = sizeof(addr);
#ifdef EMULATE_TALK
	CTL_MSG_OLD *omsg;
	CTL_MSG *nmsg;
	char buff[sizeof(CTL_MSG)];
	u_char type;

struct talk_request {
	struct talk_request *next;
	struct socket *udp_so;
	struct socket *tcp_so;
} *req;

	static struct talk_request *req_tbl = 0;

#endif

struct cu_header {
	uint16_t	d_family;		// destination family
	uint16_t	d_port;			// destination port
	uint32_t	d_addr;			// destination address
	uint16_t	s_family;		// source family
	uint16_t	s_port;			// source port
	uint32_t	so_addr;		// source address
	uint32_t	seqn;			// sequence number
	uint16_t	message;		// message
	uint16_t	data_type;		// data type
	uint16_t	pkt_len;		// packet length
} *cu_head;

	switch(so->so_emu) {

#ifdef EMULATE_TALK
	 case EMU_TALK:
	 case EMU_NTALK:
		/*
		 * Talk emulation. We always change the ctl_addr to get
		 * some answers from the daemon. When an ANNOUNCE comes,
		 * we send LEAVE_INVITE to the local daemons. Also when a
		 * DELETE comes, we send copies to the local daemons.
		 */
		if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
			return;

#define	IS_OLD	(so->so_emu == EMU_TALK)

#define COPY_MSG(dest, src) { dest->type = src->type; \
			      dest->id_num = src->id_num; \
			      dest->pid = src->pid; \
			      dest->addr = src->addr; \
			      dest->ctl_addr = src->ctl_addr; \
			      memcpy(&dest->l_name, &src->l_name, NAME_SIZE_OLD); \
			      memcpy(&dest->r_name, &src->r_name, NAME_SIZE_OLD); \
	         	      memcpy(&dest->r_tty, &src->r_tty, TTY_SIZE); }

#define OTOSIN(ptr, field) ((struct sockaddr_in *)&ptr->field)
/* old_sockaddr to sockaddr_in */


		if (IS_OLD) {  		/* old talk */
			omsg = mtod(m, CTL_MSG_OLD*);
			nmsg = (CTL_MSG *) buff;
			type = omsg->type;
			OTOSIN(omsg, ctl_addr)->sin_port = addr.sin_port;
			OTOSIN(omsg, ctl_addr)->sin_addr = our_addr;
                        pstrcpy(omsg->l_name, NAME_SIZE_OLD, getlogin());
		} else {		/* new talk */
			omsg = (CTL_MSG_OLD *) buff;
			nmsg = mtod(m, CTL_MSG *);
			type = nmsg->type;
			OTOSIN(nmsg, ctl_addr)->sin_port = addr.sin_port;
			OTOSIN(nmsg, ctl_addr)->sin_addr = our_addr;
                        pstrcpy(nmsg->l_name, NAME_SIZE_OLD, getlogin());
		}

		if (type == LOOK_UP)
			return;		/* for LOOK_UP this is enough */

		if (IS_OLD) {		/* make a copy of the message */
			COPY_MSG(nmsg, omsg);
			nmsg->vers = 1;
			nmsg->answer = 0;
		} else
			COPY_MSG(omsg, nmsg);

		/*
		 * If if is an ANNOUNCE message, we go through the
		 * request table to see if a tcp port has already
		 * been redirected for this socket. If not, we solisten()
		 * a new socket and add this entry to the table.
		 * The port number of the tcp socket and our IP
		 * are put to the addr field of the message structures.
		 * Then a LEAVE_INVITE is sent to both local daemon
		 * ports, 517 and 518. This is why we have two copies
		 * of the message, one in old talk and one in new talk
		 * format.
		 */

		if (type == ANNOUNCE) {
			int s;
			u_short temp_port;

			for(req = req_tbl; req; req = req->next)
				if (so == req->udp_so)
					break;  	/* found it */

			if (!req) {	/* no entry for so, create new */
				req = (struct talk_request *)
					malloc(sizeof(struct talk_request));
				req->udp_so = so;
				req->tcp_so = solisten(0,
					OTOSIN(omsg, addr)->sin_addr.s_addr,
					OTOSIN(omsg, addr)->sin_port,
					SS_FACCEPTONCE);
				req->next = req_tbl;
				req_tbl = req;
			}

			/* replace port number in addr field */
			addrlen = sizeof(addr);
			getsockname(req->tcp_so->s,
					(struct sockaddr *) &addr,
					&addrlen);
			OTOSIN(omsg, addr)->sin_port = addr.sin_port;
			OTOSIN(omsg, addr)->sin_addr = our_addr;
			OTOSIN(nmsg, addr)->sin_port = addr.sin_port;
			OTOSIN(nmsg, addr)->sin_addr = our_addr;

			/* send LEAVE_INVITEs */
			temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
			OTOSIN(omsg, ctl_addr)->sin_port = 0;
			OTOSIN(nmsg, ctl_addr)->sin_port = 0;
			omsg->type = nmsg->type = LEAVE_INVITE;

			s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
			addr.sin_addr = our_addr;
			addr.sin_family = AF_INET;
			addr.sin_port = htons(517);
			sendto(s, (char *)omsg, sizeof(*omsg), 0,
				(struct sockaddr *)&addr, sizeof(addr));
			addr.sin_port = htons(518);
			sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
				(struct sockaddr *) &addr, sizeof(addr));
			closesocket(s) ;

			omsg->type = nmsg->type = ANNOUNCE;
			OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
			OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;
		}

		/*
		 * If it is a DELETE message, we send a copy to the
		 * local daemons. Then we delete the entry corresponding
		 * to our socket from the request table.
		 */

		if (type == DELETE) {
			struct talk_request *temp_req, *req_next;
			int s;
			u_short temp_port;

			temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
			OTOSIN(omsg, ctl_addr)->sin_port = 0;
			OTOSIN(nmsg, ctl_addr)->sin_port = 0;

			s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
			addr.sin_addr = our_addr;
			addr.sin_family = AF_INET;
			addr.sin_port = htons(517);
			sendto(s, (char *)omsg, sizeof(*omsg), 0,
				(struct sockaddr *)&addr, sizeof(addr));
			addr.sin_port = htons(518);
			sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
				(struct sockaddr *)&addr, sizeof(addr));
			closesocket(s);

			OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
			OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;

			/* delete table entry */
			if (so == req_tbl->udp_so) {
				temp_req = req_tbl;
				req_tbl = req_tbl->next;
				free(temp_req);
			} else {
				temp_req = req_tbl;
				for(req = req_tbl->next; req; req = req_next) {
					req_next = req->next;
					if (so == req->udp_so) {
						temp_req->next = req_next;
						free(req);
						break;
					} else {
						temp_req = req;
					}
				}
			}
		}

		return;
#endif

	case EMU_CUSEEME:

		/*
		 * Cu-SeeMe emulation.
		 * Hopefully the packet is more that 16 bytes long. We don't
		 * do any other tests, just replace the address and port
		 * fields.
		 */
		if (m->m_len >= sizeof (*cu_head)) {
			if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
				return;
			cu_head = mtod(m, struct cu_header *);
			cu_head->s_port = addr.sin_port;
			cu_head->so_addr = our_addr.s_addr;
		}

		return;
	}
}

struct socket *
udp_listen(u_int port, u_int32_t laddr, u_int lport, int flags)
{
	struct sockaddr_in addr;
	struct socket *so;
	socklen_t addrlen = sizeof(struct sockaddr_in), opt = 1;

	if ((so = socreate()) == NULL) {
		free(so);
		return NULL;
	}
	so->s = socket(AF_INET,SOCK_DGRAM,0);
	so->so_expire = curtime + SO_EXPIRE;
	insque(so,&udb);

	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = INADDR_ANY;
	addr.sin_port = port;

	if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
		udp_detach(so);
		return NULL;
	}
	setsockopt(so->s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
/*	setsockopt(so->s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int)); */

	getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
	so->so_fport = addr.sin_port;
	if (addr.sin_addr.s_addr == 0 || addr.sin_addr.s_addr == loopback_addr.s_addr)
	   so->so_faddr = alias_addr;
	else
	   so->so_faddr = addr.sin_addr;

	so->so_lport = lport;
	so->so_laddr.s_addr = laddr;
	if (flags != SS_FACCEPTONCE)
	   so->so_expire = 0;

	so->so_state = SS_ISFCONNECTED;

	return so;
}