1/*
2 * Copyright (c) 1993, 1994, 1995, 1996, 1997
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 *
21 * savefile.c - supports offline use of tcpdump
22 *	Extraction/creation by Jeffrey Mogul, DECWRL
23 *	Modified by Steve McCanne, LBL.
24 *
25 * Used to save the received packet headers, after filtering, to
26 * a file, and then read them later.
27 * The first record in the file contains saved values for the machine
28 * dependent values so we can print the dump file on any architecture.
29 */
30
31#ifdef HAVE_CONFIG_H
32#include <config.h>
33#endif
34
35#include <pcap-types.h>
36#ifdef _WIN32
37#include <io.h>
38#include <fcntl.h>
39#endif /* _WIN32 */
40
41#include <errno.h>
42#include <memory.h>
43#include <stdio.h>
44#include <stdlib.h>
45#include <string.h>
46#include <limits.h> /* for INT_MAX */
47
48#include "pcap-int.h"
49
50#ifdef HAVE_OS_PROTO_H
51#include "os-proto.h"
52#endif
53
54#include "sf-pcap.h"
55#include "sf-pcapng.h"
56#include "pcap-common.h"
57#include "charconv.h"
58
59#ifdef _WIN32
60/*
61 * This isn't exported on Windows, because it would only work if both
62 * WinPcap/Npcap and the code using it were to use the Universal CRT; otherwise,
63 * a FILE structure in WinPcap/Npcap and a FILE structure in the code using it
64 * could be different if they're using different versions of the C runtime.
65 *
66 * Instead, pcap/pcap.h defines it as a macro that wraps the hopen version,
67 * with the wrapper calling _fileno() and _get_osfhandle() themselves,
68 * so that it convert the appropriate CRT version's FILE structure to
69 * a HANDLE (which is OS-defined, not CRT-defined, and is part of the Win32
70 * and Win64 ABIs).
71 */
72static pcap_t *pcap_fopen_offline_with_tstamp_precision(FILE *, u_int, char *);
73#endif
74
75/*
76 * Setting O_BINARY on DOS/Windows is a bit tricky
77 */
78#if defined(_WIN32)
79  #define SET_BINMODE(f)  _setmode(_fileno(f), _O_BINARY)
80#elif defined(MSDOS)
81  #if defined(__HIGHC__)
82  #define SET_BINMODE(f)  setmode(f, O_BINARY)
83  #else
84  #define SET_BINMODE(f)  setmode(fileno(f), O_BINARY)
85  #endif
86#endif
87
88static int
89sf_getnonblock(pcap_t *p _U_)
90{
91	/*
92	 * This is a savefile, not a live capture file, so never say
93	 * it's in non-blocking mode.
94	 */
95	return (0);
96}
97
98static int
99sf_setnonblock(pcap_t *p, int nonblock _U_)
100{
101	/*
102	 * This is a savefile, not a live capture file, so reject
103	 * requests to put it in non-blocking mode.  (If it's a
104	 * pipe, it could be put in non-blocking mode, but that
105	 * would significantly complicate the code to read packets,
106	 * as it would have to handle reading partial packets and
107	 * keeping the state of the read.)
108	 */
109	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
110	    "Savefiles cannot be put into non-blocking mode");
111	return (-1);
112}
113
114static int
115sf_cant_set_rfmon(pcap_t *p _U_)
116{
117	/*
118	 * This is a savefile, not a device on which you can capture,
119	 * so never say it supports being put into monitor mode.
120	 */
121	return (0);
122}
123
124static int
125sf_stats(pcap_t *p, struct pcap_stat *ps _U_)
126{
127	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
128	    "Statistics aren't available from savefiles");
129	return (-1);
130}
131
132#ifdef _WIN32
133static struct pcap_stat *
134sf_stats_ex(pcap_t *p, int *size _U_)
135{
136	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
137	    "Statistics aren't available from savefiles");
138	return (NULL);
139}
140
141static int
142sf_setbuff(pcap_t *p, int dim _U_)
143{
144	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
145	    "The kernel buffer size cannot be set while reading from a file");
146	return (-1);
147}
148
149static int
150sf_setmode(pcap_t *p, int mode _U_)
151{
152	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
153	    "impossible to set mode while reading from a file");
154	return (-1);
155}
156
157static int
158sf_setmintocopy(pcap_t *p, int size _U_)
159{
160	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
161	    "The mintocopy parameter cannot be set while reading from a file");
162	return (-1);
163}
164
165static HANDLE
166sf_getevent(pcap_t *pcap)
167{
168	(void)snprintf(pcap->errbuf, sizeof(pcap->errbuf),
169	    "The read event cannot be retrieved while reading from a file");
170	return (INVALID_HANDLE_VALUE);
171}
172
173static int
174sf_oid_get_request(pcap_t *p, bpf_u_int32 oid _U_, void *data _U_,
175    size_t *lenp _U_)
176{
177	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
178	    "An OID get request cannot be performed on a file");
179	return (PCAP_ERROR);
180}
181
182static int
183sf_oid_set_request(pcap_t *p, bpf_u_int32 oid _U_, const void *data _U_,
184    size_t *lenp _U_)
185{
186	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
187	    "An OID set request cannot be performed on a file");
188	return (PCAP_ERROR);
189}
190
191static u_int
192sf_sendqueue_transmit(pcap_t *p, pcap_send_queue *queue _U_, int sync _U_)
193{
194	pcap_strlcpy(p->errbuf, "Sending packets isn't supported on savefiles",
195	    PCAP_ERRBUF_SIZE);
196	return (0);
197}
198
199static int
200sf_setuserbuffer(pcap_t *p, int size _U_)
201{
202	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
203	    "The user buffer cannot be set when reading from a file");
204	return (-1);
205}
206
207static int
208sf_live_dump(pcap_t *p, char *filename _U_, int maxsize _U_, int maxpacks _U_)
209{
210	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
211	    "Live packet dumping cannot be performed when reading from a file");
212	return (-1);
213}
214
215static int
216sf_live_dump_ended(pcap_t *p, int sync _U_)
217{
218	snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
219	    "Live packet dumping cannot be performed on a pcap_open_dead pcap_t");
220	return (-1);
221}
222
223static PAirpcapHandle
224sf_get_airpcap_handle(pcap_t *pcap _U_)
225{
226	return (NULL);
227}
228#endif
229
230static int
231sf_inject(pcap_t *p, const void *buf _U_, int size _U_)
232{
233	pcap_strlcpy(p->errbuf, "Sending packets isn't supported on savefiles",
234	    PCAP_ERRBUF_SIZE);
235	return (-1);
236}
237
238/*
239 * Set direction flag: Which packets do we accept on a forwarding
240 * single device? IN, OUT or both?
241 */
242static int
243sf_setdirection(pcap_t *p, pcap_direction_t d _U_)
244{
245	snprintf(p->errbuf, sizeof(p->errbuf),
246	    "Setting direction is not supported on savefiles");
247	return (-1);
248}
249
250void
251sf_cleanup(pcap_t *p)
252{
253	if (p->rfile != stdin)
254		(void)fclose(p->rfile);
255	if (p->buffer != NULL)
256		free(p->buffer);
257	pcap_freecode(&p->fcode);
258}
259
260#ifdef _WIN32
261/*
262 * Wrapper for fopen() and _wfopen().
263 *
264 * If we're in UTF-8 mode, map the pathname from UTF-8 to UTF-16LE and
265 * call _wfopen().
266 *
267 * If we're not, just use fopen(); that'll treat it as being in the
268 * local code page.
269 */
270FILE *
271charset_fopen(const char *path, const char *mode)
272{
273	wchar_t *utf16_path;
274#define MAX_MODE_LEN	16
275	wchar_t utf16_mode[MAX_MODE_LEN+1];
276	int i;
277	char c;
278	FILE *fp;
279	int save_errno;
280
281	if (pcap_utf_8_mode) {
282		/*
283		 * Map from UTF-8 to UTF-16LE.
284		 * Fail if there are invalid characters in the input
285		 * string, rather than converting them to REPLACEMENT
286		 * CHARACTER; the latter is appropriate for strings
287		 * to be displayed to the user, but for file names
288		 * you just want the attempt to open the file to fail.
289		 */
290		utf16_path = cp_to_utf_16le(CP_UTF8, path,
291		    MB_ERR_INVALID_CHARS);
292		if (utf16_path == NULL) {
293			/*
294			 * Error.  Assume errno has been set.
295			 *
296			 * XXX - what about Windows errors?
297			 */
298			return (NULL);
299		}
300
301		/*
302		 * Now convert the mode to UTF-16LE as well.
303		 * We assume the mode is ASCII, and that
304		 * it's short, so that's easy.
305		 */
306		for (i = 0; (c = *mode) != '\0'; i++, mode++) {
307			if (c > 0x7F) {
308				/* Not an ASCII character; fail with EINVAL. */
309				free(utf16_path);
310				errno = EINVAL;
311				return (NULL);
312			}
313			if (i >= MAX_MODE_LEN) {
314				/* The mode string is longer than we allow. */
315				free(utf16_path);
316				errno = EINVAL;
317				return (NULL);
318			}
319			utf16_mode[i] = c;
320		}
321		utf16_mode[i] = '\0';
322
323		/*
324		 * OK, we have UTF-16LE strings; hand them to
325		 * _wfopen().
326		 */
327		fp = _wfopen(utf16_path, utf16_mode);
328
329		/*
330		 * Make sure freeing the UTF-16LE string doesn't
331		 * overwrite the error code we got from _wfopen().
332		 */
333		save_errno = errno;
334		free(utf16_path);
335		errno = save_errno;
336
337		return (fp);
338	} else {
339		/*
340		 * This takes strings in the local code page as an
341		 * argument.
342		 */
343		return (fopen(path, mode));
344	}
345}
346#endif
347
348pcap_t *
349pcap_open_offline_with_tstamp_precision(const char *fname, u_int precision,
350					char *errbuf)
351{
352	FILE *fp;
353	pcap_t *p;
354
355	if (fname == NULL) {
356		snprintf(errbuf, PCAP_ERRBUF_SIZE,
357		    "A null pointer was supplied as the file name");
358		return (NULL);
359	}
360	if (fname[0] == '-' && fname[1] == '\0')
361	{
362		fp = stdin;
363		if (fp == NULL) {
364			snprintf(errbuf, PCAP_ERRBUF_SIZE,
365			    "The standard input is not open");
366			return (NULL);
367		}
368#if defined(_WIN32) || defined(MSDOS)
369		/*
370		 * We're reading from the standard input, so put it in binary
371		 * mode, as savefiles are binary files.
372		 */
373		SET_BINMODE(fp);
374#endif
375	}
376	else {
377		/*
378		 * Use charset_fopen(); on Windows, it tests whether we're
379		 * in "local code page" or "UTF-8" mode, and treats the
380		 * pathname appropriately, and on other platforms, it just
381		 * wraps fopen().
382		 *
383		 * "b" is supported as of C90, so *all* UN*Xes should
384		 * support it, even though it does nothing.  For MS-DOS,
385		 * we again need it.
386		 */
387		fp = charset_fopen(fname, "rb");
388		if (fp == NULL) {
389			pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
390			    errno, "%s", fname);
391			return (NULL);
392		}
393	}
394	p = pcap_fopen_offline_with_tstamp_precision(fp, precision, errbuf);
395	if (p == NULL) {
396		if (fp != stdin)
397			fclose(fp);
398	}
399	return (p);
400}
401
402pcap_t *
403pcap_open_offline(const char *fname, char *errbuf)
404{
405	return (pcap_open_offline_with_tstamp_precision(fname,
406	    PCAP_TSTAMP_PRECISION_MICRO, errbuf));
407}
408
409#ifdef _WIN32
410pcap_t* pcap_hopen_offline_with_tstamp_precision(intptr_t osfd, u_int precision,
411    char *errbuf)
412{
413	int fd;
414	FILE *file;
415
416	fd = _open_osfhandle(osfd, _O_RDONLY);
417	if ( fd < 0 )
418	{
419		pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
420		    errno, "_open_osfhandle");
421		return NULL;
422	}
423
424	file = _fdopen(fd, "rb");
425	if ( file == NULL )
426	{
427		pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
428		    errno, "_fdopen");
429		_close(fd);
430		return NULL;
431	}
432
433	return pcap_fopen_offline_with_tstamp_precision(file, precision,
434	    errbuf);
435}
436
437pcap_t* pcap_hopen_offline(intptr_t osfd, char *errbuf)
438{
439	return pcap_hopen_offline_with_tstamp_precision(osfd,
440	    PCAP_TSTAMP_PRECISION_MICRO, errbuf);
441}
442#endif
443
444/*
445 * Given a link-layer header type and snapshot length, return a
446 * snapshot length to use when reading the file; it's guaranteed
447 * to be > 0 and <= INT_MAX.
448 *
449 * XXX - the only reason why we limit it to <= INT_MAX is so that
450 * it fits in p->snapshot, and the only reason that p->snapshot is
451 * signed is that pcap_snapshot() returns an int, not an unsigned int.
452 */
453bpf_u_int32
454pcap_adjust_snapshot(bpf_u_int32 linktype, bpf_u_int32 snaplen)
455{
456	if (snaplen == 0 || snaplen > INT_MAX) {
457		/*
458		 * Bogus snapshot length; use the maximum for this
459		 * link-layer type as a fallback.
460		 *
461		 * XXX - we don't clamp snapshot lengths that are
462		 * <= INT_MAX but > max_snaplen_for_dlt(linktype),
463		 * so a capture file could cause us to allocate
464		 * a Really Big Buffer.
465		 */
466		snaplen = max_snaplen_for_dlt(linktype);
467	}
468	return snaplen;
469}
470
471static pcap_t *(*check_headers[])(const uint8_t *, FILE *, u_int, char *, int *) = {
472	pcap_check_header,
473	pcap_ng_check_header
474};
475
476#define	N_FILE_TYPES	(sizeof check_headers / sizeof check_headers[0])
477
478#ifdef _WIN32
479static
480#endif
481pcap_t *
482pcap_fopen_offline_with_tstamp_precision(FILE *fp, u_int precision,
483    char *errbuf)
484{
485	register pcap_t *p;
486	uint8_t magic[4];
487	size_t amt_read;
488	u_int i;
489	int err;
490
491	/*
492	 * Fail if we were passed a NULL fp.
493	 *
494	 * That shouldn't happen if we're opening with a path name, but
495	 * it could happen if buggy code is opening with a FILE * and
496	 * didn't bother to make sure the FILE * isn't null.
497	 */
498	if (fp == NULL) {
499		snprintf(errbuf, PCAP_ERRBUF_SIZE,
500		    "Null FILE * pointer provided to savefile open routine");
501		return (NULL);
502	}
503
504	/*
505	 * Read the first 4 bytes of the file; the network analyzer dump
506	 * file formats we support (pcap and pcapng), and several other
507	 * formats we might support in the future (such as snoop, DOS and
508	 * Windows Sniffer, and Microsoft Network Monitor) all have magic
509	 * numbers that are unique in their first 4 bytes.
510	 */
511	amt_read = fread(&magic, 1, sizeof(magic), fp);
512	if (amt_read != sizeof(magic)) {
513		if (ferror(fp)) {
514			pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
515			    errno, "error reading dump file");
516		} else {
517			snprintf(errbuf, PCAP_ERRBUF_SIZE,
518			    "truncated dump file; tried to read %zu file header bytes, only got %zu",
519			    sizeof(magic), amt_read);
520		}
521		return (NULL);
522	}
523
524	/*
525	 * Try all file types.
526	 */
527	for (i = 0; i < N_FILE_TYPES; i++) {
528		p = (*check_headers[i])(magic, fp, precision, errbuf, &err);
529		if (p != NULL) {
530			/* Yup, that's it. */
531			goto found;
532		}
533		if (err) {
534			/*
535			 * Error trying to read the header.
536			 */
537			return (NULL);
538		}
539	}
540
541	/*
542	 * Well, who knows what this mess is....
543	 */
544	snprintf(errbuf, PCAP_ERRBUF_SIZE, "unknown file format");
545	return (NULL);
546
547found:
548	p->rfile = fp;
549
550	/* Padding only needed for live capture fcode */
551	p->fddipad = 0;
552
553#if !defined(_WIN32) && !defined(MSDOS)
554	/*
555	 * You can do "select()" and "poll()" on plain files on most
556	 * platforms, and should be able to do so on pipes.
557	 *
558	 * You can't do "select()" on anything other than sockets in
559	 * Windows, so, on Win32 systems, we don't have "selectable_fd".
560	 */
561	p->selectable_fd = fileno(fp);
562#endif
563
564	p->can_set_rfmon_op = sf_cant_set_rfmon;
565	p->read_op = pcap_offline_read;
566	p->inject_op = sf_inject;
567	p->setfilter_op = install_bpf_program;
568	p->setdirection_op = sf_setdirection;
569	p->set_datalink_op = NULL;	/* we don't support munging link-layer headers */
570	p->getnonblock_op = sf_getnonblock;
571	p->setnonblock_op = sf_setnonblock;
572	p->stats_op = sf_stats;
573#ifdef _WIN32
574	p->stats_ex_op = sf_stats_ex;
575	p->setbuff_op = sf_setbuff;
576	p->setmode_op = sf_setmode;
577	p->setmintocopy_op = sf_setmintocopy;
578	p->getevent_op = sf_getevent;
579	p->oid_get_request_op = sf_oid_get_request;
580	p->oid_set_request_op = sf_oid_set_request;
581	p->sendqueue_transmit_op = sf_sendqueue_transmit;
582	p->setuserbuffer_op = sf_setuserbuffer;
583	p->live_dump_op = sf_live_dump;
584	p->live_dump_ended_op = sf_live_dump_ended;
585	p->get_airpcap_handle_op = sf_get_airpcap_handle;
586#endif
587
588	/*
589	 * For offline captures, the standard one-shot callback can
590	 * be used for pcap_next()/pcap_next_ex().
591	 */
592	p->oneshot_callback = pcap_oneshot;
593
594	/*
595	 * Default breakloop operation.
596	 */
597	p->breakloop_op = pcap_breakloop_common;
598
599	/*
600	 * Savefiles never require special BPF code generation.
601	 */
602	p->bpf_codegen_flags = 0;
603
604	p->activated = 1;
605
606	return (p);
607}
608
609/*
610 * This isn't needed on Windows; we #define pcap_fopen_offline() as
611 * a wrapper around pcap_hopen_offline(), and we don't call it from
612 * inside this file, so it's unused.
613 */
614#ifndef _WIN32
615pcap_t *
616pcap_fopen_offline(FILE *fp, char *errbuf)
617{
618	return (pcap_fopen_offline_with_tstamp_precision(fp,
619	    PCAP_TSTAMP_PRECISION_MICRO, errbuf));
620}
621#endif
622
623/*
624 * Read packets from a capture file, and call the callback for each
625 * packet.
626 * If cnt > 0, return after 'cnt' packets, otherwise continue until eof.
627 */
628int
629pcap_offline_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
630{
631	struct bpf_insn *fcode;
632	int n = 0;
633	u_char *data;
634
635	/*
636	 * This can conceivably process more than INT_MAX packets,
637	 * which would overflow the packet count, causing it either
638	 * to look like a negative number, and thus cause us to
639	 * return a value that looks like an error, or overflow
640	 * back into positive territory, and thus cause us to
641	 * return a too-low count.
642	 *
643	 * Therefore, if the packet count is unlimited, we clip
644	 * it at INT_MAX; this routine is not expected to
645	 * process packets indefinitely, so that's not an issue.
646	 */
647	if (PACKET_COUNT_IS_UNLIMITED(cnt))
648		cnt = INT_MAX;
649
650	for (;;) {
651		struct pcap_pkthdr h;
652		int status;
653
654		/*
655		 * Has "pcap_breakloop()" been called?
656		 * If so, return immediately - if we haven't read any
657		 * packets, clear the flag and return -2 to indicate
658		 * that we were told to break out of the loop, otherwise
659		 * leave the flag set, so that the *next* call will break
660		 * out of the loop without having read any packets, and
661		 * return the number of packets we've processed so far.
662		 */
663		if (p->break_loop) {
664			if (n == 0) {
665				p->break_loop = 0;
666				return (-2);
667			} else
668				return (n);
669		}
670
671		status = p->next_packet_op(p, &h, &data);
672		if (status < 0) {
673			/*
674			 * Error.  Pass it back to the caller.
675			 */
676			return (status);
677		}
678		if (status == 0) {
679			/*
680			 * EOF.  Nothing more to process;
681			 */
682			break;
683		}
684
685		/*
686		 * OK, we've read a packet; run it through the filter
687		 * and, if it passes, process it.
688		 */
689		if ((fcode = p->fcode.bf_insns) == NULL ||
690		    pcap_filter(fcode, data, h.len, h.caplen)) {
691			(*callback)(user, &h, data);
692			n++;	/* count the packet */
693			if (n >= cnt)
694				break;
695		}
696	}
697	/*XXX this breaks semantics tcpslice expects */
698	return (n);
699}
700