File: raw_sock.c

package info (click to toggle)
kamailio 4.2.0-2+deb8u3
  • links: PTS, VCS
  • area: main
  • in suites: jessie
  • size: 56,276 kB
  • sloc: ansic: 552,836; xml: 166,484; sh: 8,659; makefile: 7,676; sql: 6,235; perl: 3,487; yacc: 3,428; python: 1,457; cpp: 1,219; php: 1,047; java: 449; pascal: 194; cs: 40; awk: 27
file content (702 lines) | stat: -rw-r--r-- 23,403 bytes parent folder | download | duplicates (2)
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
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
/* 
 * $Id$
 *
 * Copyright (C) 2010 iptelorg GmbH
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
/** raw socket functions.
 *  @file raw_sock.c
 *  @ingroup core
 *  Module: @ref core
 */
/* 
 * History:
 * --------
 *  2010-06-07  initial version (from older code) andrei
 *  2010-06-15  IP_HDRINCL raw socket support, including on-send
 *               fragmentation (andrei)
 */

#ifdef USE_RAW_SOCKS

#include "compiler_opt.h"
#include "ip_addr.h"
#include "dprint.h"
#include "str.h"
#include "rand/fastrand.h"
#include "globals.h"

#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <arpa/inet.h>
#ifndef __USE_BSD
#define __USE_BSD  /* on linux use bsd version of iphdr (more portable) */
#endif /* __USE_BSD */
#include <netinet/ip.h>
#define __FAVOR_BSD /* on linux use bsd version of udphdr (more portable) */
#include <netinet/udp.h>

#include "raw_sock.h"
#include "cfg/cfg.h"
#include "cfg_core.h"


#if defined (__OS_freebsd) || defined (__OS_netbsd) || defined(__OS_openbsd) \
	|| defined (__OS_darwin)
/** fragmentation is done by the kernel (no need to do it in userspace) */
#define RAW_IPHDR_INC_AUTO_FRAG
#endif /* __OS_* */

/* macros for converting values in the expected format */
#if defined (__OS_freebsd) || defined (__OS_netbsd) || defined (__OS_darwin)
/* on freebsd and netbsd the ip offset (along with flags) and the
   ip header length must be filled in _host_ bytes order format.
   The same is true for openbsd < 2.1.
*/
/** convert the ip offset in the format expected by the kernel. */
#define RAW_IPHDR_IP_OFF(off) (unsigned short)(off)
/** convert the ip total length in the format expected by the kernel. */
#define RAW_IPHDR_IP_LEN(tlen) (unsigned short)(tlen)

#else /* __OS_* */
/* linux, openbsd >= 2.1 a.s.o. */
/** convert the ip offset in the format expected by the kernel. */
#define RAW_IPHDR_IP_OFF(off)  htons((unsigned short)(off))
/** convert the ip total length in the format expected by the kernel. */
#define RAW_IPHDR_IP_LEN(tlen) htons((unsigned short)(tlen))

#endif /* __OS_* */

int raw_ipip = 0; /* set if raw socket is in capture mode for IPIP */


/** create and return a raw socket.
 * @param proto - protocol used (e.g. IPPROTO_UDP, IPPROTO_RAW)
 * @param ip - if not null the socket will be bound on this ip.
 * @param iface - if not null the socket will be bound to this interface
 *                (SO_BINDTODEVICE). This is supported only on linux.
 * @param iphdr_incl - set to 1 if packets send on this socket include
 *                     a pre-built ip header (some fields, like the checksum
 *                     will still be filled by the kernel, OTOH packet
 *                     fragmentation has to be done in user space).
 * @return socket on success, -1 on error
 */
int raw_socket(int proto, struct ip_addr* ip, str* iface, int iphdr_incl)
{
	int sock;
	int t;
	union sockaddr_union su;
#if defined (SO_BINDTODEVICE)
	char short_ifname[sizeof(int)];
	int ifname_len;
	char* ifname;
#endif /* SO_BINDTODEVICE */

	sock = socket(PF_INET, SOCK_RAW, proto);
	if (sock==-1)
		goto error;
	/* set socket options */
	if (iphdr_incl) {
		t=1;
		if (setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &t, sizeof(t))<0){
			ERR("raw_socket: setsockopt(IP_HDRINCL) failed: %s [%d]\n",
					strerror(errno), errno);
			goto error;
		}
	} else {
		/* IP_PKTINFO makes no sense if the ip header is included */
		/* using IP_PKTINFO */
		t=1;
#ifdef IP_PKTINFO
		if (setsockopt(sock, IPPROTO_IP, IP_PKTINFO, &t, sizeof(t))<0){
			ERR("raw_socket: setsockopt(IP_PKTINFO) failed: %s [%d]\n",
					strerror(errno), errno);
			goto error;
		}
#elif defined(IP_RECVDSTADDR)
		if (setsockopt(sock, IPPROTO_IP, IP_RECVDSTADDR, &t, sizeof(t))<0){
			ERR("raw_socket: setsockop(IP_RECVDSTADDR) failed: %s [%d]\n",
					strerror(errno), errno);
			goto error;
		}
#else
#error "no method of getting the destination ip address supported"
#endif /* IP_RECVDSTADDR / IP_PKTINFO */
	}
#if defined (IP_MTU_DISCOVER) && defined (IP_PMTUDISC_DONT)
	t=IP_PMTUDISC_DONT;
	if(setsockopt(sock, IPPROTO_IP, IP_MTU_DISCOVER, &t, sizeof(t)) ==-1){
		ERR("raw_socket: setsockopt(IP_MTU_DISCOVER): %s\n",
				strerror(errno));
		goto error;
	}
#endif /* IP_MTU_DISCOVER && IP_PMTUDISC_DONT */
	if (iface && iface->s){
#if defined (SO_BINDTODEVICE)
		/* workaround for linux bug: arg to setsockopt must have at least
		 * sizeof(int) size or EINVAL would be returned */
		if (iface->len<sizeof(int)){
			memcpy(short_ifname, iface->s, iface->len);
			short_ifname[iface->len]=0; /* make sure it's zero term */
			ifname_len=sizeof(short_ifname);
			ifname=short_ifname;
		}else{
			ifname_len=iface->len;
			ifname=iface->s;
		}
		if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, ifname_len)
						<0){
				ERR("raw_socket: could not bind to %.*s: %s [%d]\n",
							iface->len, ZSW(iface->s), strerror(errno), errno);
				goto error;
		}
#else /* !SO_BINDTODEVICE */
		/* SO_BINDTODEVICE is linux specific => cannot bind to a device */
		ERR("raw_socket: bind to device supported only on linux\n");
		goto error;
#endif /* SO_BINDTODEVICE */
	}
	/* FIXME: probe_max_receive_buffer(sock) missing */
	if (ip){
		init_su(&su, ip, 0);
		if (bind(sock, &su.s, sockaddru_len(su))==-1){
			ERR("raw_socket: bind(%s) failed: %s [%d]\n",
				ip_addr2a(ip), strerror(errno), errno);
			goto error;
		}
	}
	return sock;
error:
	if (sock!=-1) close(sock);
	return -1;
}



/** create and return an udp over ipv4  raw socket.
 * @param ip - if not null the socket will be bound on this ip.
 * @param iface - if not null the socket will be bound to this interface
 *                (SO_BINDTODEVICE).
 * @param iphdr_incl - set to 1 if packets send on this socket include
 *                     a pre-built ip header (some fields, like the checksum
 *                     will still be filled by the kernel, OTOH packet
 *                     fragmentation has to be done in user space).
 * @return socket on success, -1 on error
 */
int raw_udp4_socket(struct ip_addr* ip, str* iface, int iphdr_incl)
{
	return raw_socket(IPPROTO_UDP, ip, iface, iphdr_incl);
}



/** receives an ipv4 packet using a raw socket.
 * An ipv4 packet is received in buf, using IP_PKTINFO or IP_RECVDSTADDR.
 * from and to are filled (only the ip part the ports are 0 since this
 * function doesn't try to look beyond the IP level).
 * @param sock - raw socket
 * @param buf - detination buffer.
 * @param len - buffer len (should be enough for receiving a packet +
 *               IP header).
 * @param from - result parameter, the IP address part of it will be filled
 *                with the source address and the port with 0.
 * @param to - result parameter, the IP address part of it will be filled
 *                with the destination (local) address and the port with 0.
 * @return packet len or <0 on error: -1 (check errno),
 *        -2 no IP_PKTINFO/IP_RECVDSTADDR found or AF mismatch
 */
int recvpkt4(int sock, char* buf, int len, union sockaddr_union* from,
					union sockaddr_union* to)
{
	struct iovec iov[1];
	struct msghdr rcv_msg;
	struct cmsghdr* cmsg;
#ifdef IP_PKTINFO
	struct in_pktinfo* rcv_pktinfo;
#endif /* IP_PKTINFO */
	int n, ret;
	char msg_ctrl_buf[1024];

	iov[0].iov_base=buf;
	iov[0].iov_len=len;
	rcv_msg.msg_name=from;
	rcv_msg.msg_namelen=sockaddru_len(*from);
	rcv_msg.msg_control=msg_ctrl_buf;
	rcv_msg.msg_controllen=sizeof(msg_ctrl_buf);
	rcv_msg.msg_iov=&iov[0];
	rcv_msg.msg_iovlen=1;
	ret=-2; /* no PKT_INFO or AF mismatch */
retry:
	n=recvmsg(sock, &rcv_msg, MSG_WAITALL);
	if (unlikely(n==-1)){
		if (errno==EINTR)
			goto retry;
		ret=n;
		goto end;
	}
	/* find the pkt info */
	for (cmsg=CMSG_FIRSTHDR(&rcv_msg); cmsg; cmsg=CMSG_NXTHDR(&rcv_msg, cmsg)){
#ifdef IP_PKTINFO
		if (likely((cmsg->cmsg_level==IPPROTO_IP) &&
					(cmsg->cmsg_type==IP_PKTINFO))) {
			rcv_pktinfo=(struct in_pktinfo*)CMSG_DATA(cmsg);
			to->sin.sin_family=AF_INET;
			memcpy(&to->sin.sin_addr, &rcv_pktinfo->ipi_spec_dst.s_addr, 
									sizeof(to->sin.sin_addr));
			to->sin.sin_port=0; /* not known */
			/* interface no. in ipi_ifindex */
			ret=n; /* success */
			break;
		}
#elif defined (IP_RECVDSTADDR)
		if (likely((cmsg->cmsg_level==IPPROTO_IP) &&
					(cmsg->cmsg_type==IP_RECVDSTADDR))) {
			to->sin.sin_family=AF_INET;
			memcpy(&to->sin.sin_addr, CMSG_DATA(cmsg),
									sizeof(to->sin.sin_addr));
			to->sin.sin_port=0; /* not known */
			ret=n; /* success */
			break;
		}
#else
#error "no method of getting the destination ip address supported"
#endif /* IP_PKTINFO / IP_RECVDSTADDR */
	}
end:
	return ret;
}



/* receive an ipv4 udp packet over a raw socket.
 * The packet is copied in *buf and *buf is advanced to point to the
 * payload.  Fills from and to.
 * @param rsock - raw socket
 * @param buf - the packet will be written to where *buf points intially and
 *              then *buf will be advanced to point to the udp payload.
 * @param len - buffer length (should be enough to hold at least the
 *               ip and udp headers + 1 byte).
 * @param from - result parameter, filled with source address and port of the
 *               packet.
 * @param from - result parameter, filled with destination (local) address and
 *               port of the packet.
 * @param rf   - filter used to decide whether or not the packet is
 *                accepted/processed. If null, all the packets are accepted.
 * @return packet len or  <0 on error (-1 and -2 on recv error @see recvpkt4,
 *         -3 if the headers are invalid and -4 if the packet doesn't
 *         match the  filter).
 */
int raw_udp4_recv(int rsock, char** buf, int len, union sockaddr_union* from,
					union sockaddr_union* to, struct raw_filter* rf)
{
	int n;
	unsigned short dst_port;
	unsigned short src_port;
	struct ip_addr dst_ip;
	char* end;
	char* udph_start;
	char* udp_payload;
	struct ip iph;
	struct udphdr udph;
	unsigned short udp_len;

	n=recvpkt4(rsock, *buf, len, from, to);
	if (unlikely(n<0)) goto error;
	
	end=*buf+n;
	if (unlikely(n<((sizeof(struct ip) * raw_ipip ? 2 : 1)+sizeof(struct udphdr)))) {
		n=-3;
		goto error;
	}
	
	if(raw_ipip) 
        	*buf = *buf + sizeof(struct ip);
	
	/* FIXME: if initial buffer is aligned, one could skip the memcpy
	   and directly cast ip and udphdr pointer to the memory */
	memcpy(&iph, *buf, sizeof(struct ip));
	udph_start=*buf+iph.ip_hl*4;
	udp_payload=udph_start+sizeof(struct udphdr);
	if (unlikely(udp_payload>end)){
		n=-3;
		goto error;
	}
	memcpy(&udph, udph_start, sizeof(struct udphdr));
	udp_len=ntohs(udph.uh_ulen);
	if (unlikely((udph_start+udp_len)!=end)){
		if ((udph_start+udp_len)>end){
			n=-3;
			goto error;
		}else{
			ERR("udp length too small: %d/%d\n",
					(int)udp_len, (int)(end-udph_start));
			n=-3;
			goto error;
		}
	}
	/* advance buf */
	*buf=udp_payload;
	n=(int)(end-*buf);
	/* fill ip from the packet (needed if no PKT_INFO is used) */
	dst_ip.af=AF_INET;
	dst_ip.len=4;
	dst_ip.u.addr32[0]=iph.ip_dst.s_addr;
	/* fill dst_port */
	dst_port=ntohs(udph.uh_dport);
	ip_addr2su(to, &dst_ip, dst_port);
	/* fill src_port */
	src_port=ntohs(udph.uh_sport);
	su_setport(from, src_port);
	if (likely(rf)) {
		su2ip_addr(&dst_ip, to);
		if ( (dst_port && rf->port1 && ((dst_port<rf->port1) ||
										(dst_port>rf->port2)) ) ||
			(matchnet(&dst_ip, &rf->dst)!=1) ){
			/* no match */
			n=-4;
			goto error;
		}
	}
	
error:
	return n;
}



/** udp checksum helper: compute the pseudo-header 16-bit "sum".
 * Computes the partial checksum (no complement) of the pseudo-header.
 * It is meant to be used by udpv4_chksum().
 * @param uh - filled udp header
 * @param src - source ip address in network byte order.
 * @param dst - destination ip address in network byte order.
 * @param length - payload length (not including the udp header),
 *                 in _host_ order.
 * @return the partial checksum in host order
 */
static inline unsigned short udpv4_vhdr_sum(	struct udphdr* uh,
										struct in_addr* src,
										struct in_addr* dst,
										unsigned short length)
{
	unsigned sum;
	
	/* pseudo header */
	sum=(src->s_addr>>16)+(src->s_addr&0xffff)+
		(dst->s_addr>>16)+(dst->s_addr&0xffff)+
		htons(IPPROTO_UDP)+(uh->uh_ulen);
	/* udp header */
	sum+=(uh->uh_dport)+(uh->uh_sport)+(uh->uh_ulen) + 0 /*chksum*/; 
	/* fold it */
	sum=(sum>>16)+(sum&0xffff);
	sum+=(sum>>16);
	/* no complement */
	return ntohs((unsigned short) sum);
}



/** compute the udp over ipv4 checksum.
 * @param u - filled udp header (except checksum).
 * @param src - source ip v4 address, in _network_ byte order.
 * @param dst - destination ip v4 address, int _network_ byte order.
 * @param data - pointer to the udp payload.
 * @param length - payload length, not including the udp header and in
 *                 _host_ order. The length mist be <= 0xffff - 8
 *                 (to allow space for the udp header).
 * @return the checksum in _host_ order */
inline static unsigned short udpv4_chksum(struct udphdr* u,
							struct in_addr* src, struct in_addr* dst,
							unsigned char* data, unsigned short length)
{
	unsigned sum;
	unsigned char* end;
	sum=udpv4_vhdr_sum(u, src, dst, length);
	end=data+(length&(~0x1)); /* make sure it's even */
	/* TODO: 16 & 32 bit aligned version */
		/* not aligned */
		for(;data<end;data+=2){
			sum+=((data[0]<<8)+data[1]);
		}
		if (length&0x1)
			sum+=((*data)<<8);
	
	/* fold it */
	sum=(sum>>16)+(sum&0xffff);
	sum+=(sum>>16);
	return (unsigned short)~sum;
}



/** fill in an udp header.
 * @param u - udp header that will be filled.
 * @param from - source ip v4 address and port.
 * @param to -   destination ip v4 address and port.
 * @param buf - pointer to the payload.
 * @param len - payload length (not including the udp header).
 * @param do_chk - if set the udp checksum will be computed, else it will
 *                 be set to 0.
 * @return 0 on success, < 0 on error.
 */
inline static int mk_udp_hdr(struct udphdr* u, struct sockaddr_in* from, 
				struct sockaddr_in* to, unsigned char* buf, int len,
					int do_chk)
{
	u->uh_ulen=htons((unsigned short)len+sizeof(struct udphdr));
	u->uh_sport=from->sin_port;
	u->uh_dport=to->sin_port;
	if (do_chk)
		u->uh_sum=htons(
				udpv4_chksum(u, &from->sin_addr, &to->sin_addr,  buf, len));
	else
		u->uh_sum=0; /* no checksum */
	return 0;
}



/** fill in an ip header.
 * Note: the checksum is _not_ computed.
 * WARNING: The ip header length and offset might be filled in
 * _host_ byte order or network byte order (depending on the OS, for example
 *  freebsd needs host byte order for raw sockets with IPHDR_INC, while
 *  linux needs network byte order).
 * @param iph - ip header that will be filled.
 * @param from - source ip v4 address (network byte order).
 * @param to -   destination ip v4 address (network byte order).
 * @param payload len - payload length (not including the ip header).
 * @param proto - protocol.
 * @return 0 on success, < 0 on error.
 */
inline static int mk_ip_hdr(struct ip* iph, struct in_addr* from,
				struct in_addr* to, int payload_len, unsigned char proto)
{
	iph->ip_hl = sizeof(struct ip)/4;
	iph->ip_v = 4;
	iph->ip_tos = tos;
	/* on freebsd ip_len _must_ be in _host_ byte order instead
	   of network byte order. On linux the length is ignored (it's filled
	   automatically every time). */
	iph->ip_len = RAW_IPHDR_IP_LEN(payload_len + sizeof(struct ip));
	iph->ip_id = 0; /* 0 => will be filled automatically by the kernel */
	iph->ip_off = 0; /* frag.: first 3 bits=flags=0, last 13 bits=offset */
	iph->ip_ttl = cfg_get(core, core_cfg, udp4_raw_ttl);
	iph->ip_p = proto;
	iph->ip_src = *from;
	iph->ip_dst = *to;
	iph->ip_sum = 0;

	return 0;
}



/** send an udp packet over a non-ip_hdrincl raw socket.
 * @param rsock - raw socket
 * @param buf - data
 * @param len - data len
 * @param from - source address:port (_must_ be non-null, but the ip address
 *                can be 0, in which case it will be filled by the kernel).
 * @param to - destination address:port
 * @return  <0 on error (errno set too), number of bytes sent on success
 *          (including the udp header => on success len + udpheader size).
 */
int raw_udp4_send(int rsock, char* buf, unsigned int len,
					union sockaddr_union* from,
					union sockaddr_union* to)
{
	struct msghdr snd_msg;
	struct cmsghdr* cmsg;
#ifdef IP_PKTINFO
	struct in_pktinfo* snd_pktinfo;
#endif /* IP_PKTINFO */
	struct iovec iov[2];
	struct udphdr udp_hdr;
	char msg_ctrl_snd_buf[1024];
	int ret;

	memset(&snd_msg, 0, sizeof(snd_msg));
	snd_msg.msg_name=&to->sin;
	snd_msg.msg_namelen=sockaddru_len(*to);
	snd_msg.msg_iov=&iov[0];
	/* prepare udp header */
	mk_udp_hdr(&udp_hdr, &from->sin, &to->sin, (unsigned char*)buf, len, 1);
	iov[0].iov_base=(char*)&udp_hdr;
	iov[0].iov_len=sizeof(udp_hdr);
	iov[1].iov_base=buf;
	iov[1].iov_len=len;
	snd_msg.msg_iovlen=2;
	snd_msg.msg_control=msg_ctrl_snd_buf;
	snd_msg.msg_controllen=sizeof(msg_ctrl_snd_buf);
	/* init pktinfo cmsg */
	cmsg=CMSG_FIRSTHDR(&snd_msg);
	cmsg->cmsg_level=IPPROTO_IP;
#ifdef IP_PKTINFO
	cmsg->cmsg_type=IP_PKTINFO;
	cmsg->cmsg_len=CMSG_LEN(sizeof(struct in_pktinfo));
	snd_pktinfo=(struct in_pktinfo*)CMSG_DATA(cmsg);
	snd_pktinfo->ipi_ifindex=0;
	snd_pktinfo->ipi_spec_dst.s_addr=from->sin.sin_addr.s_addr;
#elif defined (IP_SENDSRCADDR)
	cmsg->cmsg_type=IP_SENDSRCADDR;
	cmsg->cmsg_len=CMSG_LEN(sizeof(struct in_addr));
	memcpy(CMSG_DATA(cmsg), &from->sin.sin_addr.s_addr,
							sizeof(struct in_addr));
#else
#error "no method of setting the source ip supported"
#endif /* IP_PKTINFO / IP_SENDSRCADDR */
	snd_msg.msg_controllen=cmsg->cmsg_len;
	snd_msg.msg_flags=0;
	ret=sendmsg(rsock, &snd_msg, 0);
	return ret;
}



/** send an udp packet over an IP_HDRINCL raw socket.
 * If needed, send several fragments.
 * @param rsock - raw socket
 * @param buf - data
 * @param len - data len
 * @param from - source address:port (_must_ be non-null, but the ip address
 *                can be 0, in which case it will be filled by the kernel).
 * @param to - destination address:port
 * @param mtu - maximum datagram size (including the ip header, excluding
 *              link layer headers). Minimum allowed size is 28
 *               (sizeof(ip_header + udp_header)). If mtu is lower, it will
 *               be ignored (the packet will be sent un-fragmented).
 *              0 can be used to disable fragmentation.
 * @return  <0 on error (-2: datagram too big, -1: check errno),
 *          number of bytes sent on success
 *          (including the ip & udp headers =>
 *               on success len + udpheader + ipheader size).
 */
int raw_iphdr_udp4_send(int rsock, char* buf, unsigned int len,
						union sockaddr_union* from,
						union sockaddr_union* to, unsigned short mtu)
{
	struct msghdr snd_msg;
	struct iovec iov[2];
	struct ip_udp_hdr {
		struct ip ip;
		struct udphdr udp;
	} hdr;
	unsigned int totlen;
#ifndef RAW_IPHDR_INC_AUTO_FRAG
	unsigned int ip_frag_size; /* fragment size */
	unsigned int last_frag_extra; /* extra bytes possible in the last frag */
	unsigned int ip_payload;
	unsigned int last_frag_offs;
	void* last_frag_start;
	int frg_no;
#endif /* RAW_IPHDR_INC_AUTO_FRAG */
	int ret;

	totlen = len + sizeof(hdr);
	if (unlikely(totlen) > 65535)
		return -2;
	memset(&snd_msg, 0, sizeof(snd_msg));
	snd_msg.msg_name=&to->sin;
	snd_msg.msg_namelen=sockaddru_len(*to);
	snd_msg.msg_iov=&iov[0];
	/* prepare the udp & ip headers */
	mk_udp_hdr(&hdr.udp, &from->sin, &to->sin, (unsigned char*)buf, len, 1);
	mk_ip_hdr(&hdr.ip, &from->sin.sin_addr, &to->sin.sin_addr,
				len + sizeof(hdr.udp), IPPROTO_UDP);
	iov[0].iov_base=(char*)&hdr;
	iov[0].iov_len=sizeof(hdr);
	snd_msg.msg_iovlen=2;
	snd_msg.msg_control=0;
	snd_msg.msg_controllen=0;
	snd_msg.msg_flags=0;
	/* this part changes for different fragments */
	/* packets are fragmented if mtu has a valid value (at least an
	   IP header + UDP header fit in it) and if the total length is greater
	   then the mtu */
#ifndef RAW_IPHDR_INC_AUTO_FRAG
	if (likely(totlen <= mtu || mtu <= sizeof(hdr))) {
#endif /* RAW_IPHDR_INC_AUTO_FRAG */
		iov[1].iov_base=buf;
		iov[1].iov_len=len;
		ret=sendmsg(rsock, &snd_msg, 0);
#ifndef RAW_IPHDR_INC_AUTO_FRAG
	} else {
		ip_payload = len + sizeof(hdr.udp);
		/* a fragment offset must be a multiple of 8 => its size must
		   also be a multiple of 8, except for the last fragment */
		ip_frag_size = (mtu -sizeof(hdr.ip)) & (~7);
		last_frag_extra = (mtu - sizeof(hdr.ip)) & 7; /* rest */
		frg_no = ip_payload / ip_frag_size +
				 ((ip_payload % ip_frag_size) > last_frag_extra);
		/*ip_last_frag_size = ip_payload % frag_size +
							((ip_payload % frag_size) <= last_frag_extra) *
							ip_frag_size; */
		last_frag_offs = (frg_no - 1) * ip_frag_size;
		/* if we are here mtu => sizeof(ip_h+udp_h) && payload > mtu
		   => last_frag_offs >= sizeof(hdr.udp) */
		last_frag_start = buf + last_frag_offs - sizeof(hdr.udp);
		hdr.ip.ip_id = fastrand_max(65534) + 1; /* random id, should be != 0
											  (if 0 the kernel will fill it) */
		/* send the first fragment */
		iov[1].iov_base=buf;
		/* ip_frag_size >= sizeof(hdr.udp) because we are here only
		   if mtu >= sizeof(hdr.ip) + sizeof(hdr.udp) */
		iov[1].iov_len=ip_frag_size - sizeof(hdr.udp);
		hdr.ip.ip_len = RAW_IPHDR_IP_LEN(ip_frag_size + sizeof(hdr.ip));
		hdr.ip.ip_off = RAW_IPHDR_IP_OFF(0x2000); /* set MF */
		ret=sendmsg(rsock, &snd_msg, 0);
		if (unlikely(ret < 0))
			goto end;
		/* all the other fragments, include only the ip header */
		iov[0].iov_len = sizeof(hdr.ip);
		iov[1].iov_base =  (char*)iov[1].iov_base + iov[1].iov_len;
		/* fragments between the first and the last */
		while(unlikely(iov[1].iov_base < last_frag_start)) {
			iov[1].iov_len = ip_frag_size;
			hdr.ip.ip_len = RAW_IPHDR_IP_LEN(iov[1].iov_len + sizeof(hdr.ip));
			/* set MF  */
			hdr.ip.ip_off = RAW_IPHDR_IP_OFF( (unsigned short)
									(((char*)iov[1].iov_base - (char*)buf +
										sizeof(hdr.udp)) / 8) | 0x2000 );
			ret=sendmsg(rsock, &snd_msg, 0);
			if (unlikely(ret < 0))
				goto end;
			iov[1].iov_base =  (char*)iov[1].iov_base + iov[1].iov_len;
		}
		/* last fragment */
		iov[1].iov_len = buf + len - (char*)iov[1].iov_base;
		hdr.ip.ip_len = RAW_IPHDR_IP_LEN(iov[1].iov_len + sizeof(hdr.ip));
		/* don't set MF (last fragment) */
		hdr.ip.ip_off = RAW_IPHDR_IP_OFF((unsigned short)
									(((char*)iov[1].iov_base - (char*)buf +
										sizeof(hdr.udp)) / 8) );
		ret=sendmsg(rsock, &snd_msg, 0);
		if (unlikely(ret < 0))
			goto end;
	}
end:
#endif /* RAW_IPHDR_INC_AUTO_FRAG */
	return ret;
}



#endif /* USE_RAW_SOCKS */