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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 *
13 * Fixes:
14 * Alan Cox : verify_area() calls
15 * Alan Cox : stopped close while in use off icmp
16 * messages. Not a fix but a botch that
17 * for udp at least is 'valid'.
18 * Alan Cox : Fixed icmp handling properly
19 * Alan Cox : Correct error for oversized datagrams
20 * Alan Cox : Tidied select() semantics.
21 * Alan Cox : udp_err() fixed properly, also now
22 * select and read wake correctly on errors
23 * Alan Cox : udp_send verify_area moved to avoid mem leak
24 * Alan Cox : UDP can count its memory
25 * Alan Cox : send to an unknown connection causes
26 * an ECONNREFUSED off the icmp, but
27 * does NOT close.
28 * Alan Cox : Switched to new sk_buff handlers. No more backlog!
29 * Alan Cox : Using generic datagram code. Even smaller and the PEEK
30 * bug no longer crashes it.
31 * Fred Van Kempen : Net2e support for sk->broadcast.
32 * Alan Cox : Uses skb_free_datagram
33 * Alan Cox : Added get/set sockopt support.
34 * Alan Cox : Broadcasting without option set returns EACCES.
35 * Alan Cox : No wakeup calls. Instead we now use the callbacks.
36 * Alan Cox : Use ip_tos and ip_ttl
37 * Alan Cox : SNMP Mibs
38 * Alan Cox : MSG_DONTROUTE, and 0.0.0.0 support.
39 * Matt Dillon : UDP length checks.
40 * Alan Cox : Smarter af_inet used properly.
41 * Alan Cox : Use new kernel side addressing.
42 * Alan Cox : Incorrect return on truncated datagram receive.
43 *
44 *
45 * This program is free software; you can redistribute it and/or
46 * modify it under the terms of the GNU General Public License
47 * as published by the Free Software Foundation; either version
48 * 2 of the License, or (at your option) any later version.
49 */
50
51 #include <asm/system.h>
52 #include <asm/segment.h>
53 #include <linux/types.h>
54 #include <linux/sched.h>
55 #include <linux/fcntl.h>
56 #include <linux/socket.h>
57 #include <linux/sockios.h>
58 #include <linux/in.h>
59 #include <linux/errno.h>
60 #include <linux/timer.h>
61 #include <linux/termios.h>
62 #include <linux/mm.h>
63 #include <linux/inet.h>
64 #include <linux/netdevice.h>
65 #include "snmp.h"
66 #include "ip.h"
67 #include "protocol.h"
68 #include "tcp.h"
69 #include <linux/skbuff.h>
70 #include "sock.h"
71 #include "udp.h"
72 #include "icmp.h"
73
74 /*
75 * SNMP MIB for the UDP layer
76 */
77
78 struct udp_mib udp_statistics;
79
80
81 static int udp_deliver(struct sock *sk, struct udphdr *uh, struct sk_buff *skb, struct device *dev, long saddr, long daddr, int len);
82
83 #define min(a,b) ((a)<(b)?(a):(b))
84
85
86 /*
87 * This routine is called by the ICMP module when it gets some
88 * sort of error condition. If err < 0 then the socket should
89 * be closed and the error returned to the user. If err > 0
90 * it's just the icmp type << 8 | icmp code.
91 * Header points to the ip header of the error packet. We move
92 * on past this. Then (as it used to claim before adjustment)
93 * header points to the first 8 bytes of the udp header. We need
94 * to find the appropriate port.
95 */
96
97 void udp_err(int err, unsigned char *header, unsigned long daddr,
/* ![[next]](../icons/right.png)
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*/
98 unsigned long saddr, struct inet_protocol *protocol)
99 {
100 struct udphdr *th;
101 struct sock *sk;
102 struct iphdr *ip=(struct iphdr *)header;
103
104 header += 4*ip->ihl;
105
106 /*
107 * Find the 8 bytes of post IP header ICMP included for us
108 */
109
110 th = (struct udphdr *)header;
111
112 sk = get_sock(&udp_prot, th->source, daddr, th->dest, saddr);
113
114 if (sk == NULL)
115 return; /* No socket for error */
116
117 if (err & 0xff00 ==(ICMP_SOURCE_QUENCH << 8))
118 { /* Slow down! */
119 if (sk->cong_window > 1)
120 sk->cong_window = sk->cong_window/2;
121 return;
122 }
123
124 /*
125 * Various people wanted BSD UDP semantics. Well they've come
126 * back out because they slow down response to stuff like dead
127 * or unreachable name servers and they screw term users something
128 * chronic. Oh and it violates RFC1122. So basically fix your
129 * client code people.
130 */
131
132 #ifdef CONFIG_I_AM_A_BROKEN_BSD_WEENIE
133 /*
134 * It's only fatal if we have connected to them. I'm not happy
135 * with this code. Some BSD comparisons need doing.
136 */
137
138 if (icmp_err_convert[err & 0xff].fatal && sk->state == TCP_ESTABLISHED)
139 {
140 sk->err = icmp_err_convert[err & 0xff].errno;
141 sk->error_report(sk);
142 }
143 #else
144 if (icmp_err_convert[err & 0xff].fatal)
145 {
146 sk->err = icmp_err_convert[err & 0xff].errno;
147 sk->error_report(sk);
148 }
149 #endif
150 }
151
152
153 static unsigned short udp_check(struct udphdr *uh, int len, unsigned long saddr, unsigned long daddr)
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*/
154 {
155 unsigned long sum;
156
157 __asm__( "\t addl %%ecx,%%ebx\n"
158 "\t adcl %%edx,%%ebx\n"
159 "\t adcl $0, %%ebx\n"
160 : "=b"(sum)
161 : "0"(daddr), "c"(saddr), "d"((ntohs(len) << 16) + IPPROTO_UDP*256)
162 : "cx","bx","dx" );
163
164 if (len > 3)
165 {
166 __asm__("\tclc\n"
167 "1:\n"
168 "\t lodsl\n"
169 "\t adcl %%eax, %%ebx\n"
170 "\t loop 1b\n"
171 "\t adcl $0, %%ebx\n"
172 : "=b"(sum) , "=S"(uh)
173 : "0"(sum), "c"(len/4) ,"1"(uh)
174 : "ax", "cx", "bx", "si" );
175 }
176
177 /*
178 * Convert from 32 bits to 16 bits.
179 */
180
181 __asm__("\t movl %%ebx, %%ecx\n"
182 "\t shrl $16,%%ecx\n"
183 "\t addw %%cx, %%bx\n"
184 "\t adcw $0, %%bx\n"
185 : "=b"(sum)
186 : "0"(sum)
187 : "bx", "cx");
188
189 /*
190 * Check for an extra word.
191 */
192
193 if ((len & 2) != 0)
194 {
195 __asm__("\t lodsw\n"
196 "\t addw %%ax,%%bx\n"
197 "\t adcw $0, %%bx\n"
198 : "=b"(sum), "=S"(uh)
199 : "0"(sum) ,"1"(uh)
200 : "si", "ax", "bx");
201 }
202
203 /*
204 * Now check for the extra byte.
205 */
206
207 if ((len & 1) != 0)
208 {
209 __asm__("\t lodsb\n"
210 "\t movb $0,%%ah\n"
211 "\t addw %%ax,%%bx\n"
212 "\t adcw $0, %%bx\n"
213 : "=b"(sum)
214 : "0"(sum) ,"S"(uh)
215 : "si", "ax", "bx");
216 }
217
218 /*
219 * We only want the bottom 16 bits, but we never cleared the top 16.
220 */
221
222 return((~sum) & 0xffff);
223 }
224
225 /*
226 * Generate UDP checksums. These may be disabled, eg for fast NFS over ethernet
227 * We default them enabled.. if you turn them off you either know what you are
228 * doing or get burned...
229 */
230
231 static void udp_send_check(struct udphdr *uh, unsigned long saddr,
/* */
232 unsigned long daddr, int len, struct sock *sk)
233 {
234 uh->check = 0;
235 if (sk && sk->no_check)
236 return;
237 uh->check = udp_check(uh, len, saddr, daddr);
238
239 /*
240 * FFFF and 0 are the same, pick the right one as 0 in the
241 * actual field means no checksum.
242 */
243
244 if (uh->check == 0)
245 uh->check = 0xffff;
246 }
247
248
249 static int udp_send(struct sock *sk, struct sockaddr_in *sin,
/* */
250 unsigned char *from, int len, int rt)
251 {
252 struct sk_buff *skb;
253 struct device *dev;
254 struct udphdr *uh;
255 unsigned char *buff;
256 unsigned long saddr;
257 int size, tmp;
258 int ttl;
259
260 /*
261 * Allocate an sk_buff copy of the packet.
262 */
263
264 size = sk->prot->max_header + len;
265 skb = sock_alloc_send_skb(sk, size, 0, &tmp);
266
267
268 if (skb == NULL)
269 return tmp;
270
271 skb->sk = NULL; /* to avoid changing sk->saddr */
272 skb->free = 1;
273 skb->localroute = sk->localroute|(rt&MSG_DONTROUTE);
274
275 /*
276 * Now build the IP and MAC header.
277 */
278
279 buff = skb->data;
280 saddr = sk->saddr;
281 dev = NULL;
282 ttl = sk->ip_ttl;
283 #ifdef CONFIG_IP_MULTICAST
284 if (MULTICAST(sin->sin_addr.s_addr))
285 ttl = sk->ip_mc_ttl;
286 #endif
287 tmp = sk->prot->build_header(skb, saddr, sin->sin_addr.s_addr,
288 &dev, IPPROTO_UDP, sk->opt, skb->mem_len,sk->ip_tos,ttl);
289
290 skb->sk=sk; /* So memory is freed correctly */
291
292 /*
293 * Unable to put a header on the packet.
294 */
295
296 if (tmp < 0 )
297 {
298 sk->prot->wfree(sk, skb->mem_addr, skb->mem_len);
299 return(tmp);
300 }
301
302 buff += tmp;
303 saddr = skb->saddr; /*dev->pa_addr;*/
304 skb->len = tmp + sizeof(struct udphdr) + len; /* len + UDP + IP + MAC */
305 skb->dev = dev;
306
307 /*
308 * Fill in the UDP header.
309 */
310
311 uh = (struct udphdr *) buff;
312 uh->len = htons(len + sizeof(struct udphdr));
313 uh->source = sk->dummy_th.source;
314 uh->dest = sin->sin_port;
315 buff = (unsigned char *) (uh + 1);
316
317 /*
318 * Copy the user data.
319 */
320
321 memcpy_fromfs(buff, from, len);
322
323 /*
324 * Set up the UDP checksum.
325 */
326
327 udp_send_check(uh, saddr, sin->sin_addr.s_addr, skb->len - tmp, sk);
328
329 /*
330 * Send the datagram to the interface.
331 */
332
333 udp_statistics.UdpOutDatagrams++;
334
335 sk->prot->queue_xmit(sk, dev, skb, 1);
336 return(len);
337 }
338
339
340 static int udp_sendto(struct sock *sk, unsigned char *from, int len, int noblock,
/* */
341 unsigned flags, struct sockaddr_in *usin, int addr_len)
342 {
343 struct sockaddr_in sin;
344 int tmp;
345
346 /*
347 * Check the flags. We support no flags for UDP sending
348 */
349 if (flags&~MSG_DONTROUTE)
350 return(-EINVAL);
351 /*
352 * Get and verify the address.
353 */
354
355 if (usin)
356 {
357 if (addr_len < sizeof(sin))
358 return(-EINVAL);
359 memcpy(&sin,usin,sizeof(sin));
360 if (sin.sin_family && sin.sin_family != AF_INET)
361 return(-EINVAL);
362 if (sin.sin_port == 0)
363 return(-EINVAL);
364 }
365 else
366 {
367 if (sk->state != TCP_ESTABLISHED)
368 return(-EINVAL);
369 sin.sin_family = AF_INET;
370 sin.sin_port = sk->dummy_th.dest;
371 sin.sin_addr.s_addr = sk->daddr;
372 }
373
374 /*
375 * BSD socket semantics. You must set SO_BROADCAST to permit
376 * broadcasting of data.
377 */
378
379 if(sin.sin_addr.s_addr==INADDR_ANY)
380 sin.sin_addr.s_addr=ip_my_addr();
381
382 if(!sk->broadcast && ip_chk_addr(sin.sin_addr.s_addr)==IS_BROADCAST)
383 return -EACCES; /* Must turn broadcast on first */
384
385 sk->inuse = 1;
386
387 /* Send the packet. */
388 tmp = udp_send(sk, &sin, from, len, flags);
389
390 /* The datagram has been sent off. Release the socket. */
391 release_sock(sk);
392 return(tmp);
393 }
394
395 /*
396 * In BSD SOCK_DGRAM a write is just like a send.
397 */
398
399 static int udp_write(struct sock *sk, unsigned char *buff, int len, int noblock,
/* */
400 unsigned flags)
401 {
402 return(udp_sendto(sk, buff, len, noblock, flags, NULL, 0));
403 }
404
405
406 /*
407 * IOCTL requests applicable to the UDP protocol
408 */
409
410 int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
/* */
411 {
412 int err;
413 switch(cmd)
414 {
415 case TIOCOUTQ:
416 {
417 unsigned long amount;
418
419 if (sk->state == TCP_LISTEN) return(-EINVAL);
420 amount = sk->prot->wspace(sk)/*/2*/;
421 err=verify_area(VERIFY_WRITE,(void *)arg,
422 sizeof(unsigned long));
423 if(err)
424 return(err);
425 put_fs_long(amount,(unsigned long *)arg);
426 return(0);
427 }
428
429 case TIOCINQ:
430 {
431 struct sk_buff *skb;
432 unsigned long amount;
433
434 if (sk->state == TCP_LISTEN) return(-EINVAL);
435 amount = 0;
436 skb = skb_peek(&sk->receive_queue);
437 if (skb != NULL) {
438 /*
439 * We will only return the amount
440 * of this packet since that is all
441 * that will be read.
442 */
443 amount = skb->len;
444 }
445 err=verify_area(VERIFY_WRITE,(void *)arg,
446 sizeof(unsigned long));
447 if(err)
448 return(err);
449 put_fs_long(amount,(unsigned long *)arg);
450 return(0);
451 }
452
453 default:
454 return(-EINVAL);
455 }
456 return(0);
457 }
458
459
460 /*
461 * This should be easy, if there is something there we\
462 * return it, otherwise we block.
463 */
464
465 int udp_recvfrom(struct sock *sk, unsigned char *to, int len,
/* */
466 int noblock, unsigned flags, struct sockaddr_in *sin,
467 int *addr_len)
468 {
469 int copied = 0;
470 int truesize;
471 struct sk_buff *skb;
472 int er;
473
474 /*
475 * Check any passed addresses
476 */
477
478 if (addr_len)
479 *addr_len=sizeof(*sin);
480
481 /*
482 * From here the generic datagram does a lot of the work. Come
483 * the finished NET3, it will do _ALL_ the work!
484 */
485
486 skb=skb_recv_datagram(sk,flags,noblock,&er);
487 if(skb==NULL)
488 return er;
489
490 truesize = skb->len;
491 copied = min(len, truesize);
492
493 /*
494 * FIXME : should use udp header size info value
495 */
496
497 skb_copy_datagram(skb,sizeof(struct udphdr),to,copied);
498 sk->stamp=skb->stamp;
499
500 /* Copy the address. */
501 if (sin)
502 {
503 sin->sin_family = AF_INET;
504 sin->sin_port = skb->h.uh->source;
505 sin->sin_addr.s_addr = skb->daddr;
506 }
507
508 skb_free_datagram(skb);
509 release_sock(sk);
510 return(truesize);
511 }
512
513 /*
514 * Read has the same semantics as recv in SOCK_DGRAM
515 */
516
517 int udp_read(struct sock *sk, unsigned char *buff, int len, int noblock,
/* */
518 unsigned flags)
519 {
520 return(udp_recvfrom(sk, buff, len, noblock, flags, NULL, NULL));
521 }
522
523
524 int udp_connect(struct sock *sk, struct sockaddr_in *usin, int addr_len)
/* */
525 {
526 if (addr_len < sizeof(*usin))
527 return(-EINVAL);
528
529 if (usin->sin_family && usin->sin_family != AF_INET)
530 return(-EAFNOSUPPORT);
531 if (usin->sin_addr.s_addr==INADDR_ANY)
532 usin->sin_addr.s_addr=ip_my_addr();
533
534 if(!sk->broadcast && ip_chk_addr(usin->sin_addr.s_addr)==IS_BROADCAST)
535 return -EACCES; /* Must turn broadcast on first */
536
537 sk->daddr = usin->sin_addr.s_addr;
538 sk->dummy_th.dest = usin->sin_port;
539 sk->state = TCP_ESTABLISHED;
540 return(0);
541 }
542
543
544 static void udp_close(struct sock *sk, int timeout)
/* */
545 {
546 sk->inuse = 1;
547 sk->state = TCP_CLOSE;
548 if (sk->dead)
549 destroy_sock(sk);
550 else
551 release_sock(sk);
552 }
553
554
555 /*
556 * All we need to do is get the socket, and then do a checksum.
557 */
558
559 int udp_rcv(struct sk_buff *skb, struct device *dev, struct options *opt,
/* */
560 unsigned long daddr, unsigned short len,
561 unsigned long saddr, int redo, struct inet_protocol *protocol)
562 {
563 struct sock *sk;
564 struct udphdr *uh;
565 unsigned short ulen;
566 int addr_type = IS_MYADDR;
567
568 if(!dev || dev->pa_addr!=daddr)
569 addr_type=ip_chk_addr(daddr);
570
571 /*
572 * Get the header.
573 */
574 uh = (struct udphdr *) skb->h.uh;
575
576 ip_statistics.IpInDelivers++;
577
578 /*
579 * Validate the packet and the UDP length.
580 */
581
582 ulen = ntohs(uh->len);
583
584 if (ulen > len || len < sizeof(*uh) || ulen < sizeof(*uh))
585 {
586 printk("UDP: short packet: %d/%d\n", ulen, len);
587 udp_statistics.UdpInErrors++;
588 kfree_skb(skb, FREE_WRITE);
589 return(0);
590 }
591
592 if (uh->check && udp_check(uh, len, saddr, daddr))
593 {
594 printk("UDP: bad checksum.\n");
595 udp_statistics.UdpInErrors++;
596 kfree_skb(skb, FREE_WRITE);
597 return(0);
598 }
599
600
601 len=ulen;
602
603 #ifdef CONFIG_IP_MULTICAST
604 if (addr_type!=IS_MYADDR)
605 {
606 /*
607 * Multicasts and broadcasts go to each listener.
608 */
609 struct sock *sknext=NULL;
610 sk=get_sock_mcast(udp_prot.sock_array[ntohs(uh->dest)&(SOCK_ARRAY_SIZE-1)], uh->dest,
611 saddr, uh->source, daddr);
612 if(sk)
613 {
614 do
615 {
616 struct sk_buff *skb1;
617
618 sknext=get_sock_mcast(sk->next, uh->dest, saddr, uh->source, daddr);
619 if(sknext)
620 skb1=skb_clone(skb,GFP_ATOMIC);
621 else
622 skb1=skb;
623 if(skb1)
624 udp_deliver(sk, uh, skb1, dev,saddr,daddr,len);
625 sk=sknext;
626 }
627 while(sknext!=NULL);
628 }
629 else
630 kfree_skb(skb, FREE_READ);
631 return 0;
632 }
633 #endif
634 sk = get_sock(&udp_prot, uh->dest, saddr, uh->source, daddr);
635 if (sk == NULL)
636 {
637 udp_statistics.UdpNoPorts++;
638 if (addr_type == IS_MYADDR)
639 {
640 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, dev);
641 }
642 /*
643 * Hmm. We got an UDP broadcast to a port to which we
644 * don't wanna listen. Ignore it.
645 */
646 skb->sk = NULL;
647 kfree_skb(skb, FREE_WRITE);
648 return(0);
649 }
650
651 return udp_deliver(sk,uh,skb,dev, saddr, daddr, len);
652 }
653
654 static int udp_deliver(struct sock *sk, struct udphdr *uh, struct sk_buff *skb, struct device *dev, long saddr, long daddr, int len)
/* ![[last]](../icons/n_last.png)
*/
655 {
656 skb->sk = sk;
657 skb->dev = dev;
658 skb->len = len;
659
660 /*
661 * These are supposed to be switched.
662 */
663
664 skb->daddr = saddr;
665 skb->saddr = daddr;
666
667
668 /*
669 * Charge it to the socket, dropping if the queue is full.
670 */
671
672 skb->len = len - sizeof(*uh);
673
674 if (sock_queue_rcv_skb(sk,skb)<0)
675 {
676 udp_statistics.UdpInErrors++;
677 ip_statistics.IpInDiscards++;
678 ip_statistics.IpInDelivers--;
679 skb->sk = NULL;
680 kfree_skb(skb, FREE_WRITE);
681 release_sock(sk);
682 return(0);
683 }
684 udp_statistics.UdpInDatagrams++;
685 release_sock(sk);
686 return(0);
687 }
688
689
690 struct proto udp_prot = {
691 sock_wmalloc,
692 sock_rmalloc,
693 sock_wfree,
694 sock_rfree,
695 sock_rspace,
696 sock_wspace,
697 udp_close,
698 udp_read,
699 udp_write,
700 udp_sendto,
701 udp_recvfrom,
702 ip_build_header,
703 udp_connect,
704 NULL,
705 ip_queue_xmit,
706 ip_retransmit,
707 NULL,
708 NULL,
709 udp_rcv,
710 datagram_select,
711 udp_ioctl,
712 NULL,
713 NULL,
714 ip_setsockopt,
715 ip_getsockopt,
716 128,
717 0,
718 {NULL,},
719 "UDP"
720 };
721
![[bottom]](../icons/n_bottom.png){kind=icon}
*/