/*
* Copyright (c) 1993, 1994, 1995, 1996, 1997
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
* the University nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior
* written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* sf-pcap.c - libpcap-file-format-specific code from savefile.c
* Extraction/creation by Jeffrey Mogul, DECWRL
* Modified by Steve McCanne, LBL.
*
* Used to save the received packet headers, after filtering, to
* a file, and then read them later.
* The first record in the file contains saved values for the machine
* dependent values so we can print the dump file on any architecture.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <pcap-types.h>
#ifdef _WIN32
#include <io.h>
#include <fcntl.h>
#endif /* _WIN32 */
#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pcap-int.h"
#include "pcap-common.h"
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#include "sf-pcap.h"
/*
* Setting O_BINARY on DOS/Windows is a bit tricky
*/
#if defined(_WIN32)
#define SET_BINMODE(f) _setmode(_fileno(f), _O_BINARY)
#elif defined(MSDOS)
#if defined(__HIGHC__)
#define SET_BINMODE(f) setmode(f, O_BINARY)
#else
#define SET_BINMODE(f) setmode(fileno(f), O_BINARY)
#endif
#endif
/*
* Standard libpcap format.
*/
#define TCPDUMP_MAGIC 0xa1b2c3d4
/*
* Alexey Kuznetzov's modified libpcap format.
*/
#define KUZNETZOV_TCPDUMP_MAGIC 0xa1b2cd34
/*
* Reserved for Francisco Mesquita <francisco.mesquita@radiomovel.pt>
* for another modified format.
*/
#define FMESQUITA_TCPDUMP_MAGIC 0xa1b234cd
/*
* Navtel Communcations' format, with nanosecond timestamps,
* as per a request from Dumas Hwang <dumas.hwang@navtelcom.com>.
*/
#define NAVTEL_TCPDUMP_MAGIC 0xa12b3c4d
/*
* Normal libpcap format, except for seconds/nanoseconds timestamps,
* as per a request by Ulf Lamping <ulf.lamping@web.de>
*/
#define NSEC_TCPDUMP_MAGIC 0xa1b23c4d
/*
* Mechanism for storing information about a capture in the upper
* 6 bits of a linktype value in a capture file.
*
* LT_LINKTYPE_EXT(x) extracts the additional information.
*
* The rest of the bits are for a value describing the link-layer
* value. LT_LINKTYPE(x) extracts that value.
*/
#define LT_LINKTYPE(x) ((x) & 0x03FFFFFF)
#define LT_LINKTYPE_EXT(x) ((x) & 0xFC000000)
static int pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **datap);
/*
* Private data for reading pcap savefiles.
*/
typedef enum {
NOT_SWAPPED,
SWAPPED,
MAYBE_SWAPPED
} swapped_type_t;
typedef enum {
PASS_THROUGH,
SCALE_UP,
SCALE_DOWN
} tstamp_scale_type_t;
struct pcap_sf {
size_t hdrsize;
swapped_type_t lengths_swapped;
tstamp_scale_type_t scale_type;
};
/*
* Check whether this is a pcap savefile and, if it is, extract the
* relevant information from the header.
*/
pcap_t *
pcap_check_header(bpf_u_int32 magic, FILE *fp, u_int precision, char *errbuf,
int *err)
{
struct pcap_file_header hdr;
size_t amt_read;
pcap_t *p;
int swapped = 0;
struct pcap_sf *ps;
/*
* Assume no read errors.
*/
*err = 0;
/*
* Check whether the first 4 bytes of the file are the magic
* number for a pcap savefile, or for a byte-swapped pcap
* savefile.
*/
if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC &&
magic != NSEC_TCPDUMP_MAGIC) {
magic = SWAPLONG(magic);
if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC &&
magic != NSEC_TCPDUMP_MAGIC)
return (NULL); /* nope */
swapped = 1;
}
/*
* They are. Put the magic number in the header, and read
* the rest of the header.
*/
hdr.magic = magic;
amt_read = fread(((char *)&hdr) + sizeof hdr.magic, 1,
sizeof(hdr) - sizeof(hdr.magic), fp);
if (amt_read != sizeof(hdr) - sizeof(hdr.magic)) {
if (ferror(fp)) {
pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
errno, "error reading dump file");
} else {
pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %lu file header bytes, only got %lu",
(unsigned long)sizeof(hdr),
(unsigned long)amt_read);
}
*err = 1;
return (NULL);
}
/*
* If it's a byte-swapped capture file, byte-swap the header.
*/
if (swapped) {
hdr.version_major = SWAPSHORT(hdr.version_major);
hdr.version_minor = SWAPSHORT(hdr.version_minor);
hdr.thiszone = SWAPLONG(hdr.thiszone);
hdr.sigfigs = SWAPLONG(hdr.sigfigs);
hdr.snaplen = SWAPLONG(hdr.snaplen);
hdr.linktype = SWAPLONG(hdr.linktype);
}
if (hdr.version_major < PCAP_VERSION_MAJOR) {
pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
"archaic pcap savefile format");
*err = 1;
return (NULL);
}
/*
* currently only versions 2.[0-4] are supported with
* the exception of 543.0 for DG/UX tcpdump.
*/
if (! ((hdr.version_major == PCAP_VERSION_MAJOR &&
hdr.version_minor <= PCAP_VERSION_MINOR) ||
(hdr.version_major == 543 &&
hdr.version_minor == 0))) {
pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
"unsupported pcap savefile version %u.%u",
hdr.version_major, hdr.version_minor);
*err = 1;
return NULL;
}
/*
* OK, this is a good pcap file.
* Allocate a pcap_t for it.
*/
p = pcap_open_offline_common(errbuf, sizeof (struct pcap_sf));
if (p == NULL) {
/* Allocation failed. */
*err = 1;
return (NULL);
}
p->swapped = swapped;
p->version_major = hdr.version_major;
p->version_minor = hdr.version_minor;
p->tzoff = hdr.thiszone;
p->snapshot = hdr.snaplen;
if (p->snapshot <= 0) {
/*
* Bogus snapshot length; use the maximum for this
* link-layer type as a fallback.
*
* XXX - the only reason why snapshot is signed is
* that pcap_snapshot() returns an int, not an
* unsigned int.
*/
p->snapshot = max_snaplen_for_dlt(hdr.linktype);
}
p->linktype = linktype_to_dlt(LT_LINKTYPE(hdr.linktype));
p->linktype_ext = LT_LINKTYPE_EXT(hdr.linktype);
p->next_packet_op = pcap_next_packet;
ps = p->priv;
p->opt.tstamp_precision = precision;
/*
* Will we need to scale the timestamps to match what the
* user wants?
*/
switch (precision) {
case PCAP_TSTAMP_PRECISION_MICRO:
if (magic == NSEC_TCPDUMP_MAGIC) {
/*
* The file has nanoseconds, the user
* wants microseconds; scale the
* precision down.
*/
ps->scale_type = SCALE_DOWN;
} else {
/*
* The file has microseconds, the
* user wants microseconds; nothing to do.
*/
ps->scale_type = PASS_THROUGH;
}
break;
case PCAP_TSTAMP_PRECISION_NANO:
if (magic == NSEC_TCPDUMP_MAGIC) {
/*
* The file has nanoseconds, the
* user wants nanoseconds; nothing to do.
*/
ps->scale_type = PASS_THROUGH;
} else {
/*
* The file has microoseconds, the user
* wants nanoseconds; scale the
* precision up.
*/
ps->scale_type = SCALE_UP;
}
break;
default:
pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
"unknown time stamp resolution %u", precision);
free(p);
*err = 1;
return (NULL);
}
/*
* We interchanged the caplen and len fields at version 2.3,
* in order to match the bpf header layout. But unfortunately
* some files were written with version 2.3 in their headers
* but without the interchanged fields.
*
* In addition, DG/UX tcpdump writes out files with a version
* number of 543.0, and with the caplen and len fields in the
* pre-2.3 order.
*/
switch (hdr.version_major) {
case 2:
if (hdr.version_minor < 3)
ps->lengths_swapped = SWAPPED;
else if (hdr.version_minor == 3)
ps->lengths_swapped = MAYBE_SWAPPED;
else
ps->lengths_swapped = NOT_SWAPPED;
break;
case 543:
ps->lengths_swapped = SWAPPED;
break;
default:
ps->lengths_swapped = NOT_SWAPPED;
break;
}
if (magic == KUZNETZOV_TCPDUMP_MAGIC) {
/*
* XXX - the patch that's in some versions of libpcap
* changes the packet header but not the magic number,
* and some other versions with this magic number have
* some extra debugging information in the packet header;
* we'd have to use some hacks^H^H^H^H^Hheuristics to
* detect those variants.
*
* Ethereal does that, but it does so by trying to read
* the first two packets of the file with each of the
* record header formats. That currently means it seeks
* backwards and retries the reads, which doesn't work
* on pipes. We want to be able to read from a pipe, so
* that strategy won't work; we'd have to buffer some
* data ourselves and read from that buffer in order to
* make that work.
*/
ps->hdrsize = sizeof(struct pcap_sf_patched_pkthdr);
if (p->linktype == DLT_EN10MB) {
/*
* This capture might have been done in raw mode
* or cooked mode.
*
* If it was done in cooked mode, p->snapshot was
* passed to recvfrom() as the buffer size, meaning
* that the most packet data that would be copied
* would be p->snapshot. However, a faked Ethernet
* header would then have been added to it, so the
* most data that would be in a packet in the file
* would be p->snapshot + 14.
*
* We can't easily tell whether the capture was done
* in raw mode or cooked mode, so we'll assume it was
* cooked mode, and add 14 to the snapshot length.
* That means that, for a raw capture, the snapshot
* length will be misleading if you use it to figure
* out why a capture doesn't have all the packet data,
* but there's not much we can do to avoid that.
*/
p->snapshot += 14;
}
} else
ps->hdrsize = sizeof(struct pcap_sf_pkthdr);
/*
* Allocate a buffer for the packet data.
* Choose the minimum of the file's snapshot length and 2K bytes;
* that should be enough for most network packets - we'll grow it
* if necessary. That way, we don't allocate a huge chunk of
* memory just because there's a huge snapshot length, as the
* snapshot length might be larger than the size of the largest
* packet.
*/
p->bufsize = p->snapshot;
if (p->bufsize > 2048)
p->bufsize = 2048;
p->buffer = malloc(p->bufsize);
if (p->buffer == NULL) {
pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
free(p);
*err = 1;
return (NULL);
}
p->cleanup_op = sf_cleanup;
return (p);
}
/*
* Grow the packet buffer to the specified size.
*/
static int
grow_buffer(pcap_t *p, u_int bufsize)
{
void *bigger_buffer;
bigger_buffer = realloc(p->buffer, bufsize);
if (bigger_buffer == NULL) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "out of memory");
return (0);
}
p->buffer = bigger_buffer;
p->bufsize = bufsize;
return (1);
}
/*
* Read and return the next packet from the savefile. Return the header
* in hdr and a pointer to the contents in data. Return 0 on success, 1
* if there were no more packets, and -1 on an error.
*/
static int
pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
{
struct pcap_sf *ps = p->priv;
struct pcap_sf_patched_pkthdr sf_hdr;
FILE *fp = p->rfile;
size_t amt_read;
bpf_u_int32 t;
/*
* Read the packet header; the structure we use as a buffer
* is the longer structure for files generated by the patched
* libpcap, but if the file has the magic number for an
* unpatched libpcap we only read as many bytes as the regular
* header has.
*/
amt_read = fread(&sf_hdr, 1, ps->hdrsize, fp);
if (amt_read != ps->hdrsize) {
if (ferror(fp)) {
pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "error reading dump file");
return (-1);
} else {
if (amt_read != 0) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %lu header bytes, only got %lu",
(unsigned long)ps->hdrsize,
(unsigned long)amt_read);
return (-1);
}
/* EOF */
return (1);
}
}
if (p->swapped) {
/* these were written in opposite byte order */
hdr->caplen = SWAPLONG(sf_hdr.caplen);
hdr->len = SWAPLONG(sf_hdr.len);
hdr->ts.tv_sec = SWAPLONG(sf_hdr.ts.tv_sec);
hdr->ts.tv_usec = SWAPLONG(sf_hdr.ts.tv_usec);
} else {
hdr->caplen = sf_hdr.caplen;
hdr->len = sf_hdr.len;
hdr->ts.tv_sec = sf_hdr.ts.tv_sec;
hdr->ts.tv_usec = sf_hdr.ts.tv_usec;
}
switch (ps->scale_type) {
case PASS_THROUGH:
/*
* Just pass the time stamp through.
*/
break;
case SCALE_UP:
/*
* File has microseconds, user wants nanoseconds; convert
* it.
*/
hdr->ts.tv_usec = hdr->ts.tv_usec * 1000;
break;
case SCALE_DOWN:
/*
* File has nanoseconds, user wants microseconds; convert
* it.
*/
hdr->ts.tv_usec = hdr->ts.tv_usec / 1000;
break;
}
/* Swap the caplen and len fields, if necessary. */
switch (ps->lengths_swapped) {
case NOT_SWAPPED:
break;
case MAYBE_SWAPPED:
if (hdr->caplen <= hdr->len) {
/*
* The captured length is <= the actual length,
* so presumably they weren't swapped.
*/
break;
}
/* FALLTHROUGH */
case SWAPPED:
t = hdr->caplen;
hdr->caplen = hdr->len;
hdr->len = t;
break;
}
/*
* Is the packet bigger than we consider sane?
*/
if (hdr->caplen > max_snaplen_for_dlt(p->linktype)) {
/*
* Yes. This may be a damaged or fuzzed file.
*
* Is it bigger than the snapshot length?
* (We don't treat that as an error if it's not
* bigger than the maximum we consider sane; see
* below.)
*/
if (hdr->caplen > (bpf_u_int32)p->snapshot) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"invalid packet capture length %u, bigger than "
"snaplen of %d", hdr->caplen, p->snapshot);
} else {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"invalid packet capture length %u, bigger than "
"maximum of %u", hdr->caplen,
max_snaplen_for_dlt(p->linktype));
}
return (-1);
}
if (hdr->caplen > (bpf_u_int32)p->snapshot) {
/*
* The packet is bigger than the snapshot length
* for this file.
*
* This can happen due to Solaris 2.3 systems tripping
* over the BUFMOD problem and not setting the snapshot
* length correctly in the savefile header.
*
* libpcap 0.4 and later on Solaris 2.3 should set the
* snapshot length correctly in the pcap file header,
* even though they don't set a snapshot length in bufmod
* (the buggy bufmod chops off the *beginning* of the
* packet if a snapshot length is specified); they should
* also reduce the captured length, as supplied to the
* per-packet callback, to the snapshot length if it's
* greater than the snapshot length, so the code using
* libpcap should see the packet cut off at the snapshot
* length, even though the full packet is copied up to
* userland.
*
* However, perhaps some versions of libpcap failed to
* set the snapshot length currectly in the file header
* or the per-packet header, or perhaps this is a
* corrupted safefile or a savefile built/modified by a
* fuzz tester, so we check anyway. We grow the buffer
* to be big enough for the snapshot length, read up
* to the snapshot length, discard the rest of the
* packet, and report the snapshot length as the captured
* length; we don't want to hand our caller a packet
* bigger than the snapshot length, because they might
* be assuming they'll never be handed such a packet,
* and might copy the packet into a snapshot-length-
* sized buffer, assuming it'll fit.
*/
size_t bytes_to_discard;
size_t bytes_to_read, bytes_read;
char discard_buf[4096];
if (hdr->caplen > p->bufsize) {
/*
* Grow the buffer to the snapshot length.
*/
if (!grow_buffer(p, p->snapshot))
return (-1);
}
/*
* Read the first p->snapshot bytes into the buffer.
*/
amt_read = fread(p->buffer, 1, p->snapshot, fp);
if (amt_read != (bpf_u_int32)p->snapshot) {
if (ferror(fp)) {
pcap_fmt_errmsg_for_errno(p->errbuf,
PCAP_ERRBUF_SIZE, errno,
"error reading dump file");
} else {
/*
* Yes, this uses hdr->caplen; technically,
* it's true, because we would try to read
* and discard the rest of those bytes, and
* that would fail because we got EOF before
* the read finished.
*/
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %u captured bytes, only got %lu",
p->snapshot, (unsigned long)amt_read);
}
return (-1);
}
/*
* Now read and discard what's left.
*/
bytes_to_discard = hdr->caplen - p->snapshot;
bytes_read = amt_read;
while (bytes_to_discard != 0) {
bytes_to_read = bytes_to_discard;
if (bytes_to_read > sizeof (discard_buf))
bytes_to_read = sizeof (discard_buf);
amt_read = fread(discard_buf, 1, bytes_to_read, fp);
bytes_read += amt_read;
if (amt_read != bytes_to_read) {
if (ferror(fp)) {
pcap_fmt_errmsg_for_errno(p->errbuf,
PCAP_ERRBUF_SIZE, errno,
"error reading dump file");
} else {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %u captured bytes, only got %lu",
hdr->caplen, (unsigned long)bytes_read);
}
return (-1);
}
bytes_to_discard -= amt_read;
}
/*
* Adjust caplen accordingly, so we don't get confused later
* as to how many bytes we have to play with.
*/
hdr->caplen = p->snapshot;
} else {
if (hdr->caplen > p->bufsize) {
/*
* Grow the buffer to the next power of 2, or
* the snaplen, whichever is lower.
*/
u_int new_bufsize;
new_bufsize = hdr->caplen;
/*
* http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
*/
new_bufsize--;
new_bufsize |= new_bufsize >> 1;
new_bufsize |= new_bufsize >> 2;
new_bufsize |= new_bufsize >> 4;
new_bufsize |= new_bufsize >> 8;
new_bufsize |= new_bufsize >> 16;
new_bufsize++;
if (new_bufsize > (u_int)p->snapshot)
new_bufsize = p->snapshot;
if (!grow_buffer(p, new_bufsize))
return (-1);
}
/* read the packet itself */
amt_read = fread(p->buffer, 1, hdr->caplen, fp);
if (amt_read != hdr->caplen) {
if (ferror(fp)) {
pcap_fmt_errmsg_for_errno(p->errbuf,
PCAP_ERRBUF_SIZE, errno,
"error reading dump file");
} else {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %u captured bytes, only got %lu",
hdr->caplen, (unsigned long)amt_read);
}
return (-1);
}
}
*data = p->buffer;
if (p->swapped)
swap_pseudo_headers(p->linktype, hdr, *data);
return (0);
}
static int
sf_write_header(pcap_t *p, FILE *fp, int linktype, int thiszone, int snaplen)
{
struct pcap_file_header hdr;
hdr.magic = p->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? NSEC_TCPDUMP_MAGIC : TCPDUMP_MAGIC;
hdr.version_major = PCAP_VERSION_MAJOR;
hdr.version_minor = PCAP_VERSION_MINOR;
hdr.thiszone = thiszone;
hdr.snaplen = snaplen;
hdr.sigfigs = 0;
hdr.linktype = linktype;
if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
return (-1);
return (0);
}
/*
* Output a packet to the initialized dump file.
*/
void
pcap_dump(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
register FILE *f;
struct pcap_sf_pkthdr sf_hdr;
f = (FILE *)user;
sf_hdr.ts.tv_sec = h->ts.tv_sec;
sf_hdr.ts.tv_usec = h->ts.tv_usec;
sf_hdr.caplen = h->caplen;
sf_hdr.len = h->len;
/* XXX we should check the return status */
(void)fwrite(&sf_hdr, sizeof(sf_hdr), 1, f);
(void)fwrite(sp, h->caplen, 1, f);
}
static pcap_dumper_t *
pcap_setup_dump(pcap_t *p, int linktype, FILE *f, const char *fname)
{
#if defined(_WIN32) || defined(MSDOS)
/*
* If we're writing to the standard output, put it in binary
* mode, as savefiles are binary files.
*
* Otherwise, we turn off buffering.
* XXX - why? And why not on the standard output?
*/
if (f == stdout)
SET_BINMODE(f);
else
setvbuf(f, NULL, _IONBF, 0);
#endif
if (sf_write_header(p, f, linktype, p->tzoff, p->snapshot) == -1) {
pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "Can't write to %s", fname);
if (f != stdout)
(void)fclose(f);
return (NULL);
}
return ((pcap_dumper_t *)f);
}
/*
* Initialize so that sf_write() will output to the file named 'fname'.
*/
pcap_dumper_t *
pcap_dump_open(pcap_t *p, const char *fname)
{
FILE *f;
int linktype;
/*
* If this pcap_t hasn't been activated, it doesn't have a
* link-layer type, so we can't use it.
*/
if (!p->activated) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: not-yet-activated pcap_t passed to pcap_dump_open",
fname);
return (NULL);
}
linktype = dlt_to_linktype(p->linktype);
if (linktype == -1) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: link-layer type %d isn't supported in savefiles",
fname, p->linktype);
return (NULL);
}
linktype |= p->linktype_ext;
if (fname == NULL) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"A null pointer was supplied as the file name");
return NULL;
}
if (fname[0] == '-' && fname[1] == '\0') {
f = stdout;
fname = "standard output";
} else {
/*
* "b" is supported as of C90, so *all* UN*Xes should
* support it, even though it does nothing. It's
* required on Windows, as the file is a binary file
* and must be written in binary mode.
*/
f = fopen(fname, "wb");
if (f == NULL) {
pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s", fname);
return (NULL);
}
}
return (pcap_setup_dump(p, linktype, f, fname));
}
/*
* Initialize so that sf_write() will output to the given stream.
*/
pcap_dumper_t *
pcap_dump_fopen(pcap_t *p, FILE *f)
{
int linktype;
linktype = dlt_to_linktype(p->linktype);
if (linktype == -1) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"stream: link-layer type %d isn't supported in savefiles",
p->linktype);
return (NULL);
}
linktype |= p->linktype_ext;
return (pcap_setup_dump(p, linktype, f, "stream"));
}
pcap_dumper_t *
pcap_dump_open_append(pcap_t *p, const char *fname)
{
FILE *f;
int linktype;
size_t amt_read;
struct pcap_file_header ph;
linktype = dlt_to_linktype(p->linktype);
if (linktype == -1) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: link-layer type %d isn't supported in savefiles",
fname, linktype);
return (NULL);
}
if (fname == NULL) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"A null pointer was supplied as the file name");
return NULL;
}
if (fname[0] == '-' && fname[1] == '\0')
return (pcap_setup_dump(p, linktype, stdout, "standard output"));
/*
* "b" is supported as of C90, so *all* UN*Xes should support it,
* even though it does nothing. It's required on Windows, as the
* file is a binary file and must be read in binary mode.
*/
f = fopen(fname, "rb+");
if (f == NULL) {
pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s", fname);
return (NULL);
}
/*
* Try to read a pcap header.
*/
amt_read = fread(&ph, 1, sizeof (ph), f);
if (amt_read != sizeof (ph)) {
if (ferror(f)) {
pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "%s", fname);
fclose(f);
return (NULL);
} else if (feof(f) && amt_read > 0) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: truncated pcap file header", fname);
fclose(f);
return (NULL);
}
}
#if defined(_WIN32) || defined(MSDOS)
/*
* We turn off buffering.
* XXX - why? And why not on the standard output?
*/
setvbuf(f, NULL, _IONBF, 0);
#endif
/*
* If a header is already present and:
*
* it's not for a pcap file of the appropriate resolution
* and the right byte order for this machine;
*
* the link-layer header types don't match;
*
* the snapshot lengths don't match;
*
* return an error.
*/
if (amt_read > 0) {
/*
* A header is already present.
* Do the checks.
*/
switch (ph.magic) {
case TCPDUMP_MAGIC:
if (p->opt.tstamp_precision != PCAP_TSTAMP_PRECISION_MICRO) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: different time stamp precision, cannot append to file", fname);
fclose(f);
return (NULL);
}
break;
case NSEC_TCPDUMP_MAGIC:
if (p->opt.tstamp_precision != PCAP_TSTAMP_PRECISION_NANO) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: different time stamp precision, cannot append to file", fname);
fclose(f);
return (NULL);
}
break;
case SWAPLONG(TCPDUMP_MAGIC):
case SWAPLONG(NSEC_TCPDUMP_MAGIC):
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: different byte order, cannot append to file", fname);
fclose(f);
return (NULL);
case KUZNETZOV_TCPDUMP_MAGIC:
case SWAPLONG(KUZNETZOV_TCPDUMP_MAGIC):
case NAVTEL_TCPDUMP_MAGIC:
case SWAPLONG(NAVTEL_TCPDUMP_MAGIC):
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: not a pcap file to which we can append", fname);
fclose(f);
return (NULL);
default:
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: not a pcap file", fname);
fclose(f);
return (NULL);
}
/*
* Good version?
*/
if (ph.version_major != PCAP_VERSION_MAJOR ||
ph.version_minor != PCAP_VERSION_MINOR) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: version is %u.%u, cannot append to file", fname,
ph.version_major, ph.version_minor);
fclose(f);
return (NULL);
}
if ((bpf_u_int32)linktype != ph.linktype) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: different linktype, cannot append to file", fname);
fclose(f);
return (NULL);
}
if ((bpf_u_int32)p->snapshot != ph.snaplen) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: different snaplen, cannot append to file", fname);
fclose(f);
return (NULL);
}
} else {
/*
* A header isn't present; attempt to write it.
*/
if (sf_write_header(p, f, linktype, p->tzoff, p->snapshot) == -1) {
pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "Can't write to %s", fname);
(void)fclose(f);
return (NULL);
}
}
/*
* Start writing at the end of the file.
*/
if (fseek(f, 0, SEEK_END) == -1) {
pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "Can't seek to end of %s", fname);
(void)fclose(f);
return (NULL);
}
return ((pcap_dumper_t *)f);
}
FILE *
pcap_dump_file(pcap_dumper_t *p)
{
return ((FILE *)p);
}
long
pcap_dump_ftell(pcap_dumper_t *p)
{
return (ftell((FILE *)p));
}
#if defined(HAVE_FSEEKO)
/*
* We have fseeko(), so we have ftello().
* If we have large file support (files larger than 2^31-1 bytes),
* ftello() will give us a current file position with more than 32
* bits.
*/
int64_t
pcap_dump_ftell64(pcap_dumper_t *p)
{
return (ftello((FILE *)p));
}
#elif defined(_MSC_VER)
/*
* We have Visual Studio; we support only 2005 and later, so we have
* _ftelli64().
*/
int64_t
pcap_dump_ftell64(pcap_dumper_t *p)
{
return (_ftelli64((FILE *)p));
}
#else
/*
* We don't have ftello() or _ftelli64(), so fall back on ftell().
* Either long is 64 bits, in which case ftell() should suffice,
* or this is probably an older 32-bit UN*X without large file
* support, which means you'll probably get errors trying to
* write files > 2^31-1, so it won't matter anyway.
*
* XXX - what about MinGW?
*/
int64_t
pcap_dump_ftell64(pcap_dumper_t *p)
{
return (ftell((FILE *)p));
}
#endif
int
pcap_dump_flush(pcap_dumper_t *p)
{
if (fflush((FILE *)p) == EOF)
return (-1);
else
return (0);
}
void
pcap_dump_close(pcap_dumper_t *p)
{
#ifdef notyet
if (ferror((FILE *)p))
return-an-error;
/* XXX should check return from fclose() too */
#endif
(void)fclose((FILE *)p);
}