pcap-win32.c revision 147894
1/*
2 * Copyright (c) 1999 - 2003
3 * NetGroup, Politecnico di Torino (Italy)
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the Politecnico di Torino nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 *
31 */
32
33#ifndef lint
34static const char rcsid[] _U_ =
35    "@(#) $Header: /tcpdump/master/libpcap/pcap-win32.c,v 1.25.2.2 2005/06/10 03:48:56 risso Exp $ (LBL)";
36#endif
37
38#include <pcap-int.h>
39#include <packet32.h>
40#include <Ntddndis.h>
41#ifdef HAVE_DAG_API
42#include <dagnew.h>
43#include <dagapi.h>
44#endif /* HAVE_DAG_API */
45#ifdef __MINGW32__
46int* _errno();
47#define errno (*_errno())
48#endif /* __MINGW32__ */
49
50static int pcap_setfilter_win32_npf(pcap_t *, struct bpf_program *);
51static int pcap_setfilter_win32_dag(pcap_t *, struct bpf_program *);
52static int pcap_getnonblock_win32(pcap_t *, char *);
53static int pcap_setnonblock_win32(pcap_t *, int, char *);
54
55#define	PcapBufSize 256000	/*dimension of the buffer in the pcap_t structure*/
56#define	SIZE_BUF 1000000
57
58/* Equivalent to ntohs(), but a lot faster under Windows */
59#define SWAPS(_X) ((_X & 0xff) << 8) | (_X >> 8)
60
61/*
62 * Header that the WinPcap driver associates to the packets.
63 * Once was in bpf.h
64 */
65struct bpf_hdr {
66	struct timeval	bh_tstamp;	/* time stamp */
67	bpf_u_int32	bh_caplen;	/* length of captured portion */
68	bpf_u_int32	bh_datalen;	/* original length of packet */
69	u_short		bh_hdrlen;	/* length of bpf header (this struct
70					   plus alignment padding) */
71};
72
73/* Start winsock */
74int
75wsockinit()
76{
77	WORD wVersionRequested;
78	WSADATA wsaData;
79	int err;
80	wVersionRequested = MAKEWORD( 1, 1);
81	err = WSAStartup( wVersionRequested, &wsaData );
82	if ( err != 0 )
83	{
84		return -1;
85	}
86	return 0;
87}
88
89
90static int
91pcap_stats_win32(pcap_t *p, struct pcap_stat *ps)
92{
93
94	if(PacketGetStats(p->adapter, (struct bpf_stat*)ps) != TRUE){
95		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "PacketGetStats error: %s", pcap_win32strerror());
96		return -1;
97	}
98
99	return 0;
100}
101
102static int
103pcap_read_win32_npf(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
104{
105	int cc;
106	int n = 0;
107	register u_char *bp, *ep;
108
109	cc = p->cc;
110	if (p->cc == 0) {
111		/*
112		 * Has "pcap_breakloop()" been called?
113		 */
114		if (p->break_loop) {
115			/*
116			 * Yes - clear the flag that indicates that it
117			 * has, and return -2 to indicate that we were
118			 * told to break out of the loop.
119			 */
120			p->break_loop = 0;
121			return (-2);
122		}
123
124	    /* capture the packets */
125		if(PacketReceivePacket(p->adapter,p->Packet,TRUE)==FALSE){
126			snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "read error: PacketReceivePacket failed");
127			return (-1);
128		}
129
130		cc = p->Packet->ulBytesReceived;
131
132		bp = p->Packet->Buffer;
133	}
134	else
135		bp = p->bp;
136
137	/*
138	 * Loop through each packet.
139	 */
140#define bhp ((struct bpf_hdr *)bp)
141	ep = bp + cc;
142	while (1) {
143		register int caplen, hdrlen;
144
145		/*
146		 * Has "pcap_breakloop()" been called?
147		 * If so, return immediately - if we haven't read any
148		 * packets, clear the flag and return -2 to indicate
149		 * that we were told to break out of the loop, otherwise
150		 * leave the flag set, so that the *next* call will break
151		 * out of the loop without having read any packets, and
152		 * return the number of packets we've processed so far.
153		 */
154		if (p->break_loop) {
155			if (n == 0) {
156				p->break_loop = 0;
157				return (-2);
158			} else {
159				p->bp = bp;
160				p->cc = ep - bp;
161				return (n);
162			}
163		}
164		if (bp >= ep)
165			break;
166
167		caplen = bhp->bh_caplen;
168		hdrlen = bhp->bh_hdrlen;
169
170		/*
171		 * XXX A bpf_hdr matches a pcap_pkthdr.
172		 */
173		(*callback)(user, (struct pcap_pkthdr*)bp, bp + hdrlen);
174		bp += BPF_WORDALIGN(caplen + hdrlen);
175		if (++n >= cnt && cnt > 0) {
176			p->bp = bp;
177			p->cc = ep - bp;
178			return (n);
179		}
180	}
181#undef bhp
182	p->cc = 0;
183	return (n);
184}
185
186#ifdef HAVE_DAG_API
187static int
188pcap_read_win32_dag(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
189{
190	u_char *dp = NULL;
191	int	packet_len = 0, caplen = 0;
192	struct pcap_pkthdr	pcap_header;
193	u_char *endofbuf;
194	int n = 0;
195	dag_record_t *header;
196	unsigned erf_record_len;
197	ULONGLONG ts;
198	int cc;
199	unsigned swt;
200	unsigned dfp = p->adapter->DagFastProcess;
201
202	cc = p->cc;
203	if (cc == 0) /* Get new packets only if we have processed all the ones of the previous read */
204	{
205	    /* Get new packets from the network */
206		if(PacketReceivePacket(p->adapter, p->Packet, TRUE)==FALSE){
207			snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "read error: PacketReceivePacket failed");
208			return (-1);
209		}
210
211		cc = p->Packet->ulBytesReceived;
212		if(cc == 0)
213			/* The timeout has expired but we no packets arrived */
214			return 0;
215		header = (dag_record_t*)p->adapter->DagBuffer;
216	}
217	else
218		header = (dag_record_t*)p->bp;
219
220	endofbuf = (char*)header + cc;
221
222	/*
223	 * Cycle through the packets
224	 */
225	do
226	{
227		erf_record_len = SWAPS(header->rlen);
228		if((char*)header + erf_record_len > endofbuf)
229			break;
230
231		/* Increase the number of captured packets */
232		p->md.stat.ps_recv++;
233
234		/* Find the beginning of the packet */
235		dp = ((u_char *)header) + dag_record_size;
236
237		/* Determine actual packet len */
238		switch(header->type)
239		{
240		case TYPE_ATM:
241			packet_len = ATM_SNAPLEN;
242			caplen = ATM_SNAPLEN;
243			dp += 4;
244
245			break;
246
247		case TYPE_ETH:
248			swt = SWAPS(header->wlen);
249			packet_len = swt - (p->md.dag_fcs_bits);
250			caplen = erf_record_len - dag_record_size - 2;
251			if (caplen > packet_len)
252			{
253				caplen = packet_len;
254			}
255			dp += 2;
256
257			break;
258
259		case TYPE_HDLC_POS:
260			swt = SWAPS(header->wlen);
261			packet_len = swt - (p->md.dag_fcs_bits);
262			caplen = erf_record_len - dag_record_size;
263			if (caplen > packet_len)
264			{
265				caplen = packet_len;
266			}
267
268			break;
269		}
270
271		if(caplen > p->snapshot)
272			caplen = p->snapshot;
273
274		/*
275		 * Has "pcap_breakloop()" been called?
276		 * If so, return immediately - if we haven't read any
277		 * packets, clear the flag and return -2 to indicate
278		 * that we were told to break out of the loop, otherwise
279		 * leave the flag set, so that the *next* call will break
280		 * out of the loop without having read any packets, and
281		 * return the number of packets we've processed so far.
282		 */
283		if (p->break_loop)
284		{
285			if (n == 0)
286			{
287				p->break_loop = 0;
288				return (-2);
289			}
290			else
291			{
292				p->bp = (char*)header;
293				p->cc = endofbuf - (char*)header;
294				return (n);
295			}
296		}
297
298		if(!dfp)
299		{
300			/* convert between timestamp formats */
301			ts = header->ts;
302			pcap_header.ts.tv_sec = (int)(ts >> 32);
303			ts = (ts & 0xffffffffi64) * 1000000;
304			ts += 0x80000000; /* rounding */
305			pcap_header.ts.tv_usec = (int)(ts >> 32);
306			if (pcap_header.ts.tv_usec >= 1000000) {
307				pcap_header.ts.tv_usec -= 1000000;
308				pcap_header.ts.tv_sec++;
309			}
310		}
311
312		/* No underlaying filtering system. We need to filter on our own */
313		if (p->fcode.bf_insns)
314		{
315			if (bpf_filter(p->fcode.bf_insns, dp, packet_len, caplen) == 0)
316			{
317				/* Move to next packet */
318				header = (dag_record_t*)((char*)header + erf_record_len);
319				continue;
320			}
321		}
322
323		/* Fill the header for the user suppplied callback function */
324		pcap_header.caplen = caplen;
325		pcap_header.len = packet_len;
326
327		/* Call the callback function */
328		(*callback)(user, &pcap_header, dp);
329
330		/* Move to next packet */
331		header = (dag_record_t*)((char*)header + erf_record_len);
332
333		/* Stop if the number of packets requested by user has been reached*/
334		if (++n >= cnt && cnt > 0)
335		{
336			p->bp = (char*)header;
337			p->cc = endofbuf - (char*)header;
338			return (n);
339		}
340	}
341	while((u_char*)header < endofbuf);
342
343  return 1;
344}
345#endif /* HAVE_DAG_API */
346
347/* Send a packet to the network */
348static int
349pcap_inject_win32(pcap_t *p, const void *buf, size_t size){
350	LPPACKET PacketToSend;
351
352	PacketToSend=PacketAllocatePacket();
353
354	if (PacketToSend == NULL)
355	{
356		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send error: PacketAllocatePacket failed");
357		return -1;
358	}
359
360	PacketInitPacket(PacketToSend,(PVOID)buf,size);
361	if(PacketSendPacket(p->adapter,PacketToSend,TRUE) == FALSE){
362		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send error: PacketSendPacket failed");
363		PacketFreePacket(PacketToSend);
364		return -1;
365	}
366
367	PacketFreePacket(PacketToSend);
368
369	/*
370	 * We assume it all got sent if "PacketSendPacket()" succeeded.
371	 * "pcap_inject()" is expected to return the number of bytes
372	 * sent.
373	 */
374	return size;
375}
376
377static void
378pcap_close_win32(pcap_t *p)
379{
380	pcap_close_common(p);
381	if (p->adapter != NULL) {
382		PacketCloseAdapter(p->adapter);
383		p->adapter = NULL;
384	}
385	if (p->Packet) {
386		PacketFreePacket(p->Packet);
387		p->Packet = NULL;
388	}
389}
390
391pcap_t *
392pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
393    char *ebuf)
394{
395	register pcap_t *p;
396	NetType type;
397
398	/* Init WinSock */
399	wsockinit();
400
401	p = (pcap_t *)malloc(sizeof(*p));
402	if (p == NULL)
403	{
404		snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno));
405		return (NULL);
406	}
407	memset(p, 0, sizeof(*p));
408	p->adapter=NULL;
409
410	p->adapter = PacketOpenAdapter((char*)device);
411
412	if (p->adapter == NULL)
413	{
414		free(p);
415		/* Adapter detected but we are not able to open it. Return failure. */
416		snprintf(ebuf, PCAP_ERRBUF_SIZE, "Error opening adapter: %s", pcap_win32strerror());
417		return NULL;
418	}
419
420	/*get network type*/
421	if(PacketGetNetType (p->adapter,&type) == FALSE)
422	{
423		snprintf(ebuf, PCAP_ERRBUF_SIZE, "Cannot determine the network type: %s", pcap_win32strerror());
424		goto bad;
425	}
426
427	/*Set the linktype*/
428	switch (type.LinkType)
429	{
430	case NdisMediumWan:
431		p->linktype = DLT_EN10MB;
432		break;
433
434	case NdisMedium802_3:
435		p->linktype = DLT_EN10MB;
436		/*
437		 * This is (presumably) a real Ethernet capture; give it a
438		 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
439		 * that an application can let you choose it, in case you're
440		 * capturing DOCSIS traffic that a Cisco Cable Modem
441		 * Termination System is putting out onto an Ethernet (it
442		 * doesn't put an Ethernet header onto the wire, it puts raw
443		 * DOCSIS frames out on the wire inside the low-level
444		 * Ethernet framing).
445		 */
446		p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
447		/*
448		 * If that fails, just leave the list empty.
449		 */
450		if (p->dlt_list != NULL) {
451			p->dlt_list[0] = DLT_EN10MB;
452			p->dlt_list[1] = DLT_DOCSIS;
453			p->dlt_count = 2;
454		}
455		break;
456
457	case NdisMediumFddi:
458		p->linktype = DLT_FDDI;
459		break;
460
461	case NdisMedium802_5:
462		p->linktype = DLT_IEEE802;
463		break;
464
465	case NdisMediumArcnetRaw:
466		p->linktype = DLT_ARCNET;
467		break;
468
469	case NdisMediumArcnet878_2:
470		p->linktype = DLT_ARCNET;
471		break;
472
473	case NdisMediumAtm:
474		p->linktype = DLT_ATM_RFC1483;
475		break;
476
477	case NdisMediumCHDLC:
478		p->linktype = DLT_CHDLC;
479		break;
480
481	case NdisMediumPPPSerial:
482		p->linktype = DLT_PPP_SERIAL;
483		break;
484
485	case NdisMediumNull:
486		p->linktype = DLT_NULL;
487		break;
488
489	default:
490		p->linktype = DLT_EN10MB;			/*an unknown adapter is assumed to be ethernet*/
491		break;
492	}
493
494	/* Set promisquous mode */
495	if (promisc) PacketSetHwFilter(p->adapter,NDIS_PACKET_TYPE_PROMISCUOUS);
496	 else PacketSetHwFilter(p->adapter,NDIS_PACKET_TYPE_ALL_LOCAL);
497
498	/* Set the buffer size */
499	p->bufsize = PcapBufSize;
500
501	/* allocate Packet structure used during the capture */
502	if((p->Packet = PacketAllocatePacket())==NULL)
503	{
504		snprintf(ebuf, PCAP_ERRBUF_SIZE, "failed to allocate the PACKET structure");
505		goto bad;
506	}
507
508	if(!(p->adapter->Flags & INFO_FLAG_DAG_CARD))
509	{
510	/*
511	 * Traditional Adapter
512	 */
513
514		p->buffer = (u_char *)malloc(PcapBufSize);
515		if (p->buffer == NULL)
516		{
517			snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno));
518			goto bad;
519		}
520
521		PacketInitPacket(p->Packet,(BYTE*)p->buffer,p->bufsize);
522
523		p->snapshot = snaplen;
524
525		/* allocate the standard buffer in the driver */
526		if(PacketSetBuff( p->adapter, SIZE_BUF)==FALSE)
527		{
528			snprintf(ebuf, PCAP_ERRBUF_SIZE,"driver error: not enough memory to allocate the kernel buffer\n");
529			goto bad;
530		}
531
532		/* tell the driver to copy the buffer only if it contains at least 16K */
533		if(PacketSetMinToCopy(p->adapter,16000)==FALSE)
534		{
535			snprintf(ebuf, PCAP_ERRBUF_SIZE,"Error calling PacketSetMinToCopy: %s\n", pcap_win32strerror());
536			goto bad;
537		}
538	}
539	else
540#ifdef HAVE_DAG_API
541	{
542	/*
543	 * Dag Card
544	 */
545		LONG	status;
546		HKEY	dagkey;
547		DWORD	lptype;
548		DWORD	lpcbdata;
549		int		postype = 0;
550		char	keyname[512];
551
552		snprintf(keyname, sizeof(keyname), "%s\\CardParams\\%s",
553			"SYSTEM\\CurrentControlSet\\Services\\DAG",
554			strstr(_strlwr((char*)device), "dag"));
555		do
556		{
557			status = RegOpenKeyEx(HKEY_LOCAL_MACHINE, keyname, 0, KEY_READ, &dagkey);
558			if(status != ERROR_SUCCESS)
559				break;
560
561			status = RegQueryValueEx(dagkey,
562				"PosType",
563				NULL,
564				&lptype,
565				(char*)&postype,
566				&lpcbdata);
567
568			if(status != ERROR_SUCCESS)
569			{
570				postype = 0;
571			}
572
573			RegCloseKey(dagkey);
574		}
575		while(FALSE);
576
577
578		p->snapshot = PacketSetSnapLen(p->adapter, snaplen);
579
580		/* Set the length of the FCS associated to any packet. This value
581		 * will be subtracted to the packet length */
582		p->md.dag_fcs_bits = p->adapter->DagFcsLen;
583	}
584#else
585	goto bad;
586#endif /* HAVE_DAG_API */
587
588	PacketSetReadTimeout(p->adapter, to_ms);
589
590#ifdef HAVE_DAG_API
591	if(p->adapter->Flags & INFO_FLAG_DAG_CARD)
592	{
593		/* install dag specific handlers for read and setfilter */
594		p->read_op = pcap_read_win32_dag;
595		p->setfilter_op = pcap_setfilter_win32_dag;
596	}
597	else
598	{
599#endif /* HAVE_DAG_API */
600		/* install traditional npf handlers for read and setfilter */
601		p->read_op = pcap_read_win32_npf;
602		p->setfilter_op = pcap_setfilter_win32_npf;
603#ifdef HAVE_DAG_API
604	}
605#endif /* HAVE_DAG_API */
606	p->setdirection_op = NULL;	/* Not implemented. */
607	    /* XXX - can this be implemented on some versions of Windows? */
608	p->inject_op = pcap_inject_win32;
609	p->set_datalink_op = NULL;	/* can't change data link type */
610	p->getnonblock_op = pcap_getnonblock_win32;
611	p->setnonblock_op = pcap_setnonblock_win32;
612	p->stats_op = pcap_stats_win32;
613	p->close_op = pcap_close_win32;
614
615	return (p);
616bad:
617	if (p->adapter)
618	    PacketCloseAdapter(p->adapter);
619	if (p->buffer != NULL)
620		free(p->buffer);
621	if(p->Packet)
622		PacketFreePacket(p->Packet);
623	/*
624	 * Get rid of any link-layer type list we allocated.
625	 */
626	if (p->dlt_list != NULL)
627		free(p->dlt_list);
628	free(p);
629	return (NULL);
630}
631
632
633static int
634pcap_setfilter_win32_npf(pcap_t *p, struct bpf_program *fp)
635{
636	if(PacketSetBpf(p->adapter,fp)==FALSE){
637		/*
638		 * Kernel filter not installed.
639		 * XXX - fall back on userland filtering, as is done
640		 * on other platforms?
641		 */
642		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "Driver error: cannot set bpf filter: %s", pcap_win32strerror());
643		return (-1);
644	}
645
646	/*
647	 * Discard any previously-received packets, as they might have
648	 * passed whatever filter was formerly in effect, but might
649	 * not pass this filter (BIOCSETF discards packets buffered
650	 * in the kernel, so you can lose packets in any case).
651	 */
652	p->cc = 0;
653	return (0);
654}
655
656/*
657 * We filter at user level, since the kernel driver does't process the packets
658 */
659static int
660pcap_setfilter_win32_dag(pcap_t *p, struct bpf_program *fp) {
661
662	if(!fp)
663	{
664		strncpy(p->errbuf, "setfilter: No filter specified", sizeof(p->errbuf));
665		return -1;
666	}
667
668	/* Install a user level filter */
669	if (install_bpf_program(p, fp) < 0)
670	{
671		snprintf(p->errbuf, sizeof(p->errbuf),
672			"setfilter, unable to install the filter: %s", pcap_strerror(errno));
673		return -1;
674	}
675
676	p->md.use_bpf = 0;
677
678	return (0);
679}
680
681static int
682pcap_getnonblock_win32(pcap_t *p, char *errbuf)
683{
684	/*
685	 * XXX - if there were a PacketGetReadTimeout() call, we
686	 * would use it, and return 1 if the timeout is -1
687	 * and 0 otherwise.
688	 */
689	return (p->nonblock);
690}
691
692static int
693pcap_setnonblock_win32(pcap_t *p, int nonblock, char *errbuf)
694{
695	int newtimeout;
696
697	if (nonblock) {
698		/*
699		 * Set the read timeout to -1 for non-blocking mode.
700		 */
701		newtimeout = -1;
702	} else {
703		/*
704		 * Restore the timeout set when the device was opened.
705		 * (Note that this may be -1, in which case we're not
706		 * really leaving non-blocking mode.)
707		 */
708		newtimeout = p->timeout;
709	}
710	if (!PacketSetReadTimeout(p->adapter, newtimeout)) {
711		snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
712		    "PacketSetReadTimeout: %s", pcap_win32strerror());
713		return (-1);
714	}
715	p->nonblock = (newtimeout == -1);
716	return (0);
717}
718
719/* Set the driver working mode */
720int
721pcap_setmode(pcap_t *p, int mode){
722
723	if (p->adapter==NULL)
724	{
725		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "impossible to set mode while reading from a file");
726		return -1;
727	}
728
729	if(PacketSetMode(p->adapter,mode)==FALSE)
730	{
731		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "driver error: working mode not recognized");
732		return -1;
733	}
734
735	return 0;
736}
737
738/* Set the dimension of the kernel-level capture buffer */
739int
740pcap_setbuff(pcap_t *p, int dim)
741{
742	if (p->adapter==NULL)
743	{
744		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "The kernel buffer size cannot be set while reading from a file");
745		return -1;
746	}
747
748	if(PacketSetBuff(p->adapter,dim)==FALSE)
749	{
750		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "driver error: not enough memory to allocate the kernel buffer");
751		return -1;
752	}
753	return 0;
754}
755
756/*set the minimum amount of data that will release a read call*/
757int
758pcap_setmintocopy(pcap_t *p, int size)
759{
760	if (p->adapter==NULL)
761	{
762		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "Impossible to set the mintocopy parameter on an offline capture");
763		return -1;
764	}
765
766	if(PacketSetMinToCopy(p->adapter, size)==FALSE)
767	{
768		snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "driver error: unable to set the requested mintocopy size");
769		return -1;
770	}
771	return 0;
772}
773