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*/
1 /*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * The User Datagram Protocol (UDP).
7 *
8 * Version: @(#)udp.c 1.0.13 06/02/93
9 *
10 * Authors: Ross Biro, <bir7@leland.Stanford.Edu>
11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
13 * Alan Cox, <Alan.Cox@linux.org>
14 *
15 * Fixes:
16 * Alan Cox : verify_area() calls
17 * Alan Cox : stopped close while in use off icmp
18 * messages. Not a fix but a botch that
19 * for udp at least is 'valid'.
20 * Alan Cox : Fixed icmp handling properly
21 * Alan Cox : Correct error for oversized datagrams
22 * Alan Cox : Tidied select() semantics.
23 * Alan Cox : udp_err() fixed properly, also now
24 * select and read wake correctly on errors
25 * Alan Cox : udp_send verify_area moved to avoid mem leak
26 * Alan Cox : UDP can count its memory
27 * Alan Cox : send to an unknown connection causes
28 * an ECONNREFUSED off the icmp, but
29 * does NOT close.
30 * Alan Cox : Switched to new sk_buff handlers. No more backlog!
31 * Alan Cox : Using generic datagram code. Even smaller and the PEEK
32 * bug no longer crashes it.
33 * Fred Van Kempen : Net2e support for sk->broadcast.
34 * Alan Cox : Uses skb_free_datagram
35 * Alan Cox : Added get/set sockopt support.
36 * Alan Cox : Broadcasting without option set returns EACCES.
37 * Alan Cox : No wakeup calls. Instead we now use the callbacks.
38 * Alan Cox : Use ip_tos and ip_ttl
39 * Alan Cox : SNMP Mibs
40 * Alan Cox : MSG_DONTROUTE, and 0.0.0.0 support.
41 * Matt Dillon : UDP length checks.
42 * Alan Cox : Smarter af_inet used properly.
43 * Alan Cox : Use new kernel side addressing.
44 * Alan Cox : Incorrect return on truncated datagram receive.
45 * Arnt Gulbrandsen : New udp_send and stuff
46 * Alan Cox : Cache last socket
47 * Alan Cox : Route cache
48 * Jon Peatfield : Minor efficiency fix to sendto().
49 * Mike Shaver : RFC1122 checks.
50 * Alan Cox : Nonblocking error fix.
51 *
52 *
53 * This program is free software; you can redistribute it and/or
54 * modify it under the terms of the GNU General Public License
55 * as published by the Free Software Foundation; either version
56 * 2 of the License, or (at your option) any later version.
57 */
58
59 /* RFC1122 Status:
60 4.1.3.1 (Ports):
61 SHOULD send ICMP_PORT_UNREACHABLE in response to datagrams to
62 an un-listened port. (OK)
63 4.1.3.2 (IP Options)
64 MUST pass IP options from IP -> application (OK)
65 MUST allow application to specify IP options (OK)
66 4.1.3.3 (ICMP Messages)
67 MUST pass ICMP error messages to application (OK)
68 4.1.3.4 (UDP Checksums)
69 MUST provide facility for checksumming (OK)
70 MAY allow application to control checksumming (OK)
71 MUST default to checksumming on (OK)
72 MUST discard silently datagrams with bad csums (OK)
73 4.1.3.5 (UDP Multihoming)
74 MUST allow application to specify source address (OK)
75 SHOULD be able to communicate the chosen src addr up to application
76 when application doesn't choose (NOT YET - doesn't seem to be in the BSD API)
77 [Does opening a SOCK_PACKET and snooping your output count 8)]
78 4.1.3.6 (Invalid Addresses)
79 MUST discard invalid source addresses (NOT YET -- will be implemented
80 in IP, so UDP will eventually be OK. Right now it's a violation.)
81 MUST only send datagrams with one of our addresses (NOT YET - ought to be OK )
82 950728 -- MS
83 */
84
85 #include <asm/system.h>
86 #include <asm/segment.h>
87 #include <linux/types.h>
88 #include <linux/sched.h>
89 #include <linux/fcntl.h>
90 #include <linux/socket.h>
91 #include <linux/sockios.h>
92 #include <linux/in.h>
93 #include <linux/errno.h>
94 #include <linux/timer.h>
95 #include <linux/termios.h>
96 #include <linux/mm.h>
97 #include <linux/config.h>
98 #include <linux/inet.h>
99 #include <linux/netdevice.h>
100 #include <net/snmp.h>
101 #include <net/ip.h>
102 #include <net/protocol.h>
103 #include <net/tcp.h>
104 #include <linux/skbuff.h>
105 #include <net/sock.h>
106 #include <net/udp.h>
107 #include <net/icmp.h>
108 #include <net/route.h>
109 #include <net/checksum.h>
110
111 /*
112 * Snmp MIB for the UDP layer
113 */
114
115 struct udp_mib udp_statistics;
116
117 /*
118 * Cached last hit socket
119 */
120
121 volatile unsigned long uh_cache_saddr,uh_cache_daddr;
122 volatile unsigned short uh_cache_dport, uh_cache_sport;
123 volatile struct sock *uh_cache_sk;
124
125 void udp_cache_zap(void)
/* ![[next]](../icons/right.png)
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*/
126 {
127 unsigned long flags;
128 save_flags(flags);
129 cli();
130 uh_cache_saddr=0;
131 uh_cache_daddr=0;
132 uh_cache_dport=0;
133 uh_cache_sport=0;
134 uh_cache_sk=NULL;
135 restore_flags(flags);
136 }
137
138 #define min(a,b) ((a)<(b)?(a):(b))
139
140
141 /*
142 * This routine is called by the ICMP module when it gets some
143 * sort of error condition. If err < 0 then the socket should
144 * be closed and the error returned to the user. If err > 0
145 * it's just the icmp type << 8 | icmp code.
146 * Header points to the ip header of the error packet. We move
147 * on past this. Then (as it used to claim before adjustment)
148 * header points to the first 8 bytes of the udp header. We need
149 * to find the appropriate port.
150 */
151
152 void udp_err(int type, int code, unsigned char *header, __u32 daddr,
/* ![[previous]](../icons/left.png)
*/
153 __u32 saddr, struct inet_protocol *protocol)
154 {
155 struct udphdr *uh;
156 struct sock *sk;
157
158 /*
159 * Find the 8 bytes of post IP header ICMP included for us
160 */
161
162 uh = (struct udphdr *)header;
163
164 sk = get_sock(&udp_prot, uh->source, daddr, uh->dest, saddr);
165
166 if (sk == NULL)
167 return; /* No socket for error */
168
169 if (type == ICMP_SOURCE_QUENCH)
170 { /* Slow down! */
171 if (sk->cong_window > 1)
172 sk->cong_window = sk->cong_window/2;
173 return;
174 }
175
176 if (type == ICMP_PARAMETERPROB)
177 {
178 sk->err = EPROTO;
179 sk->error_report(sk);
180 return;
181 }
182
183 /*
184 * Various people wanted BSD UDP semantics. Well they've come
185 * back out because they slow down response to stuff like dead
186 * or unreachable name servers and they screw term users something
187 * chronic. Oh and it violates RFC1122. So basically fix your
188 * client code people.
189 */
190
191 /* RFC1122: OK. Passes ICMP errors back to application, as per */
192 /* 4.1.3.3. */
193 /* After the comment above, that should be no surprise. */
194
195 if (code < 13 && icmp_err_convert[code].fatal)
196 {
197 /*
198 * 4.x BSD compatibility item. Break RFC1122 to
199 * get BSD socket semantics.
200 */
201 if(sk->bsdism && sk->state!=TCP_ESTABLISHED)
202 return;
203 sk->err = icmp_err_convert[code].errno;
204 sk->error_report(sk);
205 }
206 }
207
208
209 static unsigned short udp_check(struct udphdr *uh, int len, unsigned long saddr, unsigned long daddr, unsigned long base)
/* */
210 {
211 return(csum_tcpudp_magic(saddr, daddr, len, IPPROTO_UDP, base));
212 }
213
214 struct udpfakehdr
215 {
216 struct udphdr uh;
217 __u32 daddr;
218 __u32 other;
219 const char *from;
220 __u32 wcheck;
221 };
222
223 /*
224 * Copy and checksum a UDP packet from user space into a buffer. We still have to do the planning to
225 * get ip_build_xmit to spot direct transfer to network card and provide an additional callback mode
226 * for direct user->board I/O transfers. That one will be fun.
227 */
228
229 static void udp_getfrag(const void *p, __u32 saddr, char * to, unsigned int offset, unsigned int fraglen)
/* */
230 {
231 struct udpfakehdr *ufh = (struct udpfakehdr *)p;
232 const char *src;
233 char *dst;
234 unsigned int len;
235
236 if (offset)
237 {
238 len = fraglen;
239 src = ufh->from+(offset-sizeof(struct udphdr));
240 dst = to;
241 }
242 else
243 {
244 len = fraglen-sizeof(struct udphdr);
245 src = ufh->from;
246 dst = to+sizeof(struct udphdr);
247 }
248 ufh->wcheck = csum_partial_copy_fromuser(src, dst, len, ufh->wcheck);
249 if (offset == 0)
250 {
251 ufh->wcheck = csum_partial((char *)ufh, sizeof(struct udphdr),
252 ufh->wcheck);
253 ufh->uh.check = csum_tcpudp_magic(saddr, ufh->daddr,
254 ntohs(ufh->uh.len),
255 IPPROTO_UDP, ufh->wcheck);
256 if (ufh->uh.check == 0)
257 ufh->uh.check = -1;
258 memcpy(to, ufh, sizeof(struct udphdr));
259 }
260 }
261
262 /*
263 * Unchecksummed UDP is sufficiently critical to stuff like ATM video conferencing
264 * that we use two routines for this for speed. Probably we ought to have a CONFIG_FAST_NET
265 * set for >10Mb/second boards to activate this sort of coding. Timing needed to verify if
266 * this is a valid decision.
267 */
268
269 static void udp_getfrag_nosum(const void *p, __u32 saddr, char * to, unsigned int offset, unsigned int fraglen)
/* */
270 {
271 struct udpfakehdr *ufh = (struct udpfakehdr *)p;
272 const char *src;
273 char *dst;
274 unsigned int len;
275
276 if (offset)
277 {
278 len = fraglen;
279 src = ufh->from+(offset-sizeof(struct udphdr));
280 dst = to;
281 }
282 else
283 {
284 len = fraglen-sizeof(struct udphdr);
285 src = ufh->from;
286 dst = to+sizeof(struct udphdr);
287 }
288 memcpy_fromfs(dst,src,len);
289 if (offset == 0)
290 memcpy(to, ufh, sizeof(struct udphdr));
291 }
292
293
294 /*
295 * Send UDP frames.
296 */
297
298 static int udp_send(struct sock *sk, struct sockaddr_in *sin,
/* */
299 const unsigned char *from, int len, int rt,
300 __u32 saddr, int noblock)
301 {
302 int ulen = len + sizeof(struct udphdr);
303 int a;
304 struct udpfakehdr ufh;
305
306 if(ulen>65535-sizeof(struct iphdr))
307 return -EMSGSIZE;
308
309 ufh.uh.source = sk->dummy_th.source;
310 ufh.uh.dest = sin->sin_port;
311 ufh.uh.len = htons(ulen);
312 ufh.uh.check = 0;
313 ufh.daddr = sin->sin_addr.s_addr;
314 ufh.other = (htons(ulen) << 16) + IPPROTO_UDP*256;
315 ufh.from = from;
316 ufh.wcheck = 0;
317
318 /* RFC1122: OK. Provides the checksumming facility (MUST) as per */
319 /* 4.1.3.4. It's configurable by the application via setsockopt() */
320 /* (MAY) and it defaults to on (MUST). Almost makes up for the */
321 /* violation above. -- MS */
322
323 if(sk->no_check)
324 a = ip_build_xmit(sk, udp_getfrag_nosum, &ufh, ulen,
325 sin->sin_addr.s_addr, saddr, sk->opt, rt, IPPROTO_UDP, noblock);
326 else
327 a = ip_build_xmit(sk, udp_getfrag, &ufh, ulen,
328 sin->sin_addr.s_addr, saddr, sk->opt, rt, IPPROTO_UDP, noblock);
329 if(a<0)
330 return a;
331 udp_statistics.UdpOutDatagrams++;
332 return len;
333 }
334
335
336 static int udp_sendto(struct sock *sk, const unsigned char *from, int len, int noblock,
/* */
337 unsigned flags, struct sockaddr_in *usin, int addr_len)
338 {
339 struct sockaddr_in sin;
340 int tmp;
341 __u32 saddr=0;
342
343 /*
344 * Check the flags. We support no flags for UDP sending
345 */
346
347 if (flags&~MSG_DONTROUTE)
348 return(-EINVAL);
349 /*
350 * Get and verify the address.
351 */
352
353 if (usin)
354 {
355 if (addr_len < sizeof(sin))
356 return(-EINVAL);
357 if (usin->sin_family && usin->sin_family != AF_INET)
358 return(-EINVAL);
359 if (usin->sin_port == 0)
360 return(-EINVAL);
361 }
362 else
363 {
364 if (sk->state != TCP_ESTABLISHED)
365 return(-EINVAL);
366 sin.sin_family = AF_INET;
367 sin.sin_port = sk->dummy_th.dest;
368 sin.sin_addr.s_addr = sk->daddr;
369 usin = &sin;
370 }
371
372 /*
373 * BSD socket semantics. You must set SO_BROADCAST to permit
374 * broadcasting of data.
375 */
376
377 /* RFC1122: OK. Allows the application to select the specific */
378 /* source address for an outgoing packet (MUST) as per 4.1.3.5. */
379 /* Optional addition: a mechanism for telling the application what */
380 /* address was used. (4.1.3.5, MAY) -- MS */
381
382 /* RFC1122: MUST ensure that all outgoing packets have one */
383 /* of this host's addresses as a source addr.(4.1.3.6) - bind in */
384 /* af_inet.c checks these. It does need work to allow BSD style */
385 /* bind to multicast as is done by xntpd */
386
387 if(usin->sin_addr.s_addr==INADDR_ANY)
388 usin->sin_addr.s_addr=ip_my_addr();
389
390 if(!sk->broadcast && ip_chk_addr(usin->sin_addr.s_addr)==IS_BROADCAST)
391 return -EACCES; /* Must turn broadcast on first */
392
393 lock_sock(sk);
394
395 /* Send the packet. */
396 tmp = udp_send(sk, usin, from, len, flags, saddr, noblock);
397
398 /* The datagram has been sent off. Release the socket. */
399 release_sock(sk);
400 return(tmp);
401 }
402
403 /*
404 * Temporary
405 */
406
407 static int udp_sendmsg(struct sock *sk, struct msghdr *msg, int len, int noblock,
/* */
408 int flags)
409 {
410 if(msg->msg_iovlen==1)
411 return udp_sendto(sk,msg->msg_iov[0].iov_base,len, noblock, flags, msg->msg_name, msg->msg_namelen);
412 else
413 {
414 /*
415 * For awkward cases we linearise the buffer first. In theory this is only frames
416 * whose iovec's don't split on 4 byte boundaries, and soon encrypted stuff (to keep
417 * skip happy). We are a bit more general about it.
418 */
419
420 unsigned char *buf;
421 int fs;
422 int err;
423 if(len>65515)
424 return -EMSGSIZE;
425 buf=kmalloc(len, GFP_KERNEL);
426 if(buf==NULL)
427 return -ENOBUFS;
428 memcpy_fromiovec(buf, msg->msg_iov, len);
429 fs=get_fs();
430 set_fs(get_ds());
431 err=udp_sendto(sk,buf,len, noblock, flags, msg->msg_name, msg->msg_namelen);
432 set_fs(fs);
433 kfree_s(buf,len);
434 return err;
435 }
436 }
437
438 /*
439 * IOCTL requests applicable to the UDP protocol
440 */
441
442 int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
/* */
443 {
444 int err;
445 switch(cmd)
446 {
447 case TIOCOUTQ:
448 {
449 unsigned long amount;
450
451 if (sk->state == TCP_LISTEN) return(-EINVAL);
452 amount = sock_wspace(sk);
453 err=verify_area(VERIFY_WRITE,(void *)arg,
454 sizeof(unsigned long));
455 if(err)
456 return(err);
457 put_fs_long(amount,(unsigned long *)arg);
458 return(0);
459 }
460
461 case TIOCINQ:
462 {
463 struct sk_buff *skb;
464 unsigned long amount;
465
466 if (sk->state == TCP_LISTEN) return(-EINVAL);
467 amount = 0;
468 skb = skb_peek(&sk->receive_queue);
469 if (skb != NULL) {
470 /*
471 * We will only return the amount
472 * of this packet since that is all
473 * that will be read.
474 */
475 amount = skb->len-sizeof(struct udphdr);
476 }
477 err=verify_area(VERIFY_WRITE,(void *)arg,
478 sizeof(unsigned long));
479 if(err)
480 return(err);
481 put_fs_long(amount,(unsigned long *)arg);
482 return(0);
483 }
484
485 default:
486 return(-EINVAL);
487 }
488 return(0);
489 }
490
491
492 /*
493 * This should be easy, if there is something there we\
494 * return it, otherwise we block.
495 */
496
497 int udp_recvmsg(struct sock *sk, struct msghdr *msg, int len,
/* */
498 int noblock, int flags,int *addr_len)
499 {
500 int copied = 0;
501 int truesize;
502 struct sk_buff *skb;
503 int er;
504 struct sockaddr_in *sin=(struct sockaddr_in *)msg->msg_name;
505
506 /*
507 * Check any passed addresses
508 */
509
510 if (addr_len)
511 *addr_len=sizeof(*sin);
512
513 /*
514 * From here the generic datagram does a lot of the work. Come
515 * the finished NET3, it will do _ALL_ the work!
516 */
517
518 skb=skb_recv_datagram(sk,flags,noblock,&er);
519 if(skb==NULL)
520 return er;
521
522 truesize = skb->len - sizeof(struct udphdr);
523 copied = min(len, truesize);
524
525 /*
526 * FIXME : should use udp header size info value
527 */
528
529 skb_copy_datagram_iovec(skb,sizeof(struct udphdr),msg->msg_iov,copied);
530 sk->stamp=skb->stamp;
531
532 /* Copy the address. */
533 if (sin)
534 {
535 sin->sin_family = AF_INET;
536 sin->sin_port = skb->h.uh->source;
537 sin->sin_addr.s_addr = skb->daddr;
538 }
539
540 skb_free_datagram(sk, skb);
541 return(copied);
542 }
543
544 int udp_connect(struct sock *sk, struct sockaddr_in *usin, int addr_len)
/* */
545 {
546 struct rtable *rt;
547 if (addr_len < sizeof(*usin))
548 return(-EINVAL);
549
550 if (usin->sin_family && usin->sin_family != AF_INET)
551 return(-EAFNOSUPPORT);
552 if (usin->sin_addr.s_addr==INADDR_ANY)
553 usin->sin_addr.s_addr=ip_my_addr();
554
555 if(!sk->broadcast && ip_chk_addr(usin->sin_addr.s_addr)==IS_BROADCAST)
556 return -EACCES; /* Must turn broadcast on first */
557
558 rt=ip_rt_route((__u32)usin->sin_addr.s_addr, sk->localroute);
559 if (rt==NULL)
560 return -ENETUNREACH;
561 if(!sk->saddr)
562 sk->saddr = rt->rt_src; /* Update source address */
563 if(!sk->rcv_saddr)
564 sk->rcv_saddr = rt->rt_src;
565 sk->daddr = usin->sin_addr.s_addr;
566 sk->dummy_th.dest = usin->sin_port;
567 sk->state = TCP_ESTABLISHED;
568 udp_cache_zap();
569 sk->ip_route_cache = rt;
570 return(0);
571 }
572
573
574 static void udp_close(struct sock *sk, unsigned long timeout)
/* */
575 {
576 lock_sock(sk);
577 sk->state = TCP_CLOSE;
578 if(uh_cache_sk==sk)
579 udp_cache_zap();
580 release_sock(sk);
581 destroy_sock(sk);
582 }
583
584 static inline void udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
/* */
585 {
586 /*
587 * Charge it to the socket, dropping if the queue is full.
588 */
589
590 /* I assume this includes the IP options, as per RFC1122 (4.1.3.2). */
591 /* If not, please let me know. -- MS */
592
593 if (sock_queue_rcv_skb(sk,skb)<0) {
594 udp_statistics.UdpInErrors++;
595 ip_statistics.IpInDiscards++;
596 ip_statistics.IpInDelivers--;
597 skb->sk = NULL;
598 kfree_skb(skb, FREE_WRITE);
599 return;
600 }
601 udp_statistics.UdpInDatagrams++;
602 }
603
604
605 static inline void udp_deliver(struct sock *sk, struct sk_buff *skb)
/* */
606 {
607 skb->sk = sk;
608
609 if (sk->users) {
610 __skb_queue_tail(&sk->back_log, skb);
611 return;
612 }
613 udp_queue_rcv_skb(sk, skb);
614 }
615
616 /*
617 * All we need to do is get the socket, and then do a checksum.
618 */
619
620 int udp_rcv(struct sk_buff *skb, struct device *dev, struct options *opt,
/* ![[last]](../icons/n_last.png)
*/
621 __u32 daddr, unsigned short len,
622 __u32 saddr, int redo, struct inet_protocol *protocol)
623 {
624 struct sock *sk;
625 struct udphdr *uh;
626 unsigned short ulen;
627 int addr_type;
628
629 /*
630 * If we're doing a "redo" (the socket was busy last time
631 * around), we can just queue the packet now..
632 */
633 if (redo) {
634 udp_queue_rcv_skb(skb->sk, skb);
635 return 0;
636 }
637
638 /*
639 * First time through the loop.. Do all the setup stuff
640 * (including finding out the socket we go to etc)
641 */
642
643 addr_type = IS_MYADDR;
644 if(!dev || dev->pa_addr!=daddr)
645 addr_type=ip_chk_addr(daddr);
646
647 /*
648 * Get the header.
649 */
650
651 uh = (struct udphdr *) skb->h.uh;
652
653 ip_statistics.IpInDelivers++;
654
655 /*
656 * Validate the packet and the UDP length.
657 */
658
659 ulen = ntohs(uh->len);
660
661 if (ulen > len || len < sizeof(*uh) || ulen < sizeof(*uh))
662 {
663 NETDEBUG(printk("UDP: short packet: %d/%d\n", ulen, len));
664 udp_statistics.UdpInErrors++;
665 kfree_skb(skb, FREE_WRITE);
666 return(0);
667 }
668
669 /* RFC1122 warning: According to 4.1.3.6, we MUST discard any */
670 /* datagram which has an invalid source address, either here or */
671 /* in IP. */
672 /* Right now, IP isn't doing it, and neither is UDP. It's on the */
673 /* FIXME list for IP, though, so I wouldn't worry about it. */
674 /* (That's the Right Place to do it, IMHO.) -- MS */
675
676 if (uh->check && (
677 ( (skb->ip_summed == CHECKSUM_HW) && udp_check(uh, len, saddr, daddr, skb->csum ) ) ||
678 ( (skb->ip_summed == CHECKSUM_NONE) && udp_check(uh, len, saddr, daddr,csum_partial((char*)uh, len, 0)))
679 /* skip if CHECKSUM_UNNECESSARY */
680 )
681 )
682 {
683 /* <mea@utu.fi> wants to know, who sent it, to
684 go and stomp on the garbage sender... */
685
686 /* RFC1122: OK. Discards the bad packet silently (as far as */
687 /* the network is concerned, anyway) as per 4.1.3.4 (MUST). */
688
689 NETDEBUG(printk("UDP: bad checksum. From %08lX:%d to %08lX:%d ulen %d\n",
690 ntohl(saddr),ntohs(uh->source),
691 ntohl(daddr),ntohs(uh->dest),
692 ulen));
693 udp_statistics.UdpInErrors++;
694 kfree_skb(skb, FREE_WRITE);
695 return(0);
696 }
697
698 /*
699 * These are supposed to be switched.
700 */
701
702 skb->daddr = saddr;
703 skb->saddr = daddr;
704
705 len=ulen;
706
707 skb->dev = dev;
708 skb_trim(skb,len);
709
710 #ifdef CONFIG_IP_MULTICAST
711 if (addr_type!=IS_MYADDR)
712 {
713 /*
714 * Multicasts and broadcasts go to each listener.
715 */
716 struct sock *sknext=NULL;
717 sk=get_sock_mcast(udp_prot.sock_array[ntohs(uh->dest)&(SOCK_ARRAY_SIZE-1)], uh->dest,
718 saddr, uh->source, daddr);
719 if(sk)
720 {
721 do
722 {
723 struct sk_buff *skb1;
724
725 sknext=get_sock_mcast(sk->next, uh->dest, saddr, uh->source, daddr);
726 if(sknext)
727 skb1=skb_clone(skb,GFP_ATOMIC);
728 else
729 skb1=skb;
730 if(skb1)
731 udp_deliver(sk, skb1);
732 sk=sknext;
733 }
734 while(sknext!=NULL);
735 }
736 else
737 kfree_skb(skb, FREE_READ);
738 return 0;
739 }
740 #endif
741 if(saddr==uh_cache_saddr && daddr==uh_cache_daddr && uh->dest==uh_cache_dport && uh->source==uh_cache_sport)
742 sk=(struct sock *)uh_cache_sk;
743 else
744 {
745 sk = get_sock(&udp_prot, uh->dest, saddr, uh->source, daddr);
746 uh_cache_saddr=saddr;
747 uh_cache_daddr=daddr;
748 uh_cache_dport=uh->dest;
749 uh_cache_sport=uh->source;
750 uh_cache_sk=sk;
751 }
752
753 if (sk == NULL)
754 {
755 udp_statistics.UdpNoPorts++;
756 if (addr_type == IS_MYADDR)
757 {
758 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0, dev);
759 }
760 /*
761 * Hmm. We got an UDP broadcast to a port to which we
762 * don't wanna listen. Ignore it.
763 */
764 skb->sk = NULL;
765 kfree_skb(skb, FREE_WRITE);
766 return(0);
767 }
768 udp_deliver(sk, skb);
769 return 0;
770 }
771
772 struct proto udp_prot = {
773 udp_close,
774 ip_build_header,
775 udp_connect,
776 NULL,
777 ip_queue_xmit,
778 NULL,
779 NULL,
780 NULL,
781 udp_rcv,
782 datagram_select,
783 udp_ioctl,
784 NULL,
785 NULL,
786 ip_setsockopt,
787 ip_getsockopt,
788 udp_sendmsg,
789 udp_recvmsg,
790 NULL, /* No special bind function */
791 128,
792 0,
793 "UDP",
794 0, 0,
795 {NULL,}
796 };
![[bottom]](../icons/n_bottom.png){kind=icon}
*/