nexmon – Rev 1
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/*
* 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-ng.c - pcap-ng-file-format-specific code from savefile.c
*/
#ifndef lint
static const char rcsid[] _U_ =
"@(#) $Header$ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef WIN32
#include <pcap-stdinc.h>
#else /* WIN32 */
#if HAVE_INTTYPES_H
#include <inttypes.h>
#elif HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_SYS_BITYPES_H
#include <sys/bitypes.h>
#endif
#include <sys/types.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-ng.h"
/*
* Block types.
*/
/*
* Common part at the beginning of all blocks.
*/
struct block_header {
bpf_u_int32 block_type;
bpf_u_int32 total_length;
};
/*
* Common trailer at the end of all blocks.
*/
struct block_trailer {
bpf_u_int32 total_length;
};
/*
* Common options.
*/
#define OPT_ENDOFOPT 0 /* end of options */
#define OPT_COMMENT 1 /* comment string */
/*
* Option header.
*/
struct option_header {
u_short option_code;
u_short option_length;
};
/*
* Structures for the part of each block type following the common
* part.
*/
/*
* Section Header Block.
*/
#define BT_SHB 0x0A0D0D0A
struct section_header_block {
bpf_u_int32 byte_order_magic;
u_short major_version;
u_short minor_version;
u_int64_t section_length;
/* followed by options and trailer */
};
/*
* Byte-order magic value.
*/
#define BYTE_ORDER_MAGIC 0x1A2B3C4D
/*
* Current version number. If major_version isn't PCAP_NG_VERSION_MAJOR,
* that means that this code can't read the file.
*/
#define PCAP_NG_VERSION_MAJOR 1
/*
* Interface Description Block.
*/
#define BT_IDB 0x00000001
struct interface_description_block {
u_short linktype;
u_short reserved;
bpf_u_int32 snaplen;
/* followed by options and trailer */
};
/*
* Options in the IDB.
*/
#define IF_NAME 2 /* interface name string */
#define IF_DESCRIPTION 3 /* interface description string */
#define IF_IPV4ADDR 4 /* interface's IPv4 address and netmask */
#define IF_IPV6ADDR 5 /* interface's IPv6 address and prefix length */
#define IF_MACADDR 6 /* interface's MAC address */
#define IF_EUIADDR 7 /* interface's EUI address */
#define IF_SPEED 8 /* interface's speed, in bits/s */
#define IF_TSRESOL 9 /* interface's time stamp resolution */
#define IF_TZONE 10 /* interface's time zone */
#define IF_FILTER 11 /* filter used when capturing on interface */
#define IF_OS 12 /* string OS on which capture on this interface was done */
#define IF_FCSLEN 13 /* FCS length for this interface */
#define IF_TSOFFSET 14 /* time stamp offset for this interface */
/*
* Enhanced Packet Block.
*/
#define BT_EPB 0x00000006
struct enhanced_packet_block {
bpf_u_int32 interface_id;
bpf_u_int32 timestamp_high;
bpf_u_int32 timestamp_low;
bpf_u_int32 caplen;
bpf_u_int32 len;
/* followed by packet data, options, and trailer */
};
/*
* Simple Packet Block.
*/
#define BT_SPB 0x00000003
struct simple_packet_block {
bpf_u_int32 len;
/* followed by packet data and trailer */
};
/*
* Packet Block.
*/
#define BT_PB 0x00000002
struct packet_block {
u_short interface_id;
u_short drops_count;
bpf_u_int32 timestamp_high;
bpf_u_int32 timestamp_low;
bpf_u_int32 caplen;
bpf_u_int32 len;
/* followed by packet data, options, and trailer */
};
/*
* Block cursor - used when processing the contents of a block.
* Contains a pointer into the data being processed and a count
* of bytes remaining in the block.
*/
struct block_cursor {
u_char *data;
size_t data_remaining;
bpf_u_int32 block_type;
};
typedef enum {
PASS_THROUGH,
SCALE_UP,
SCALE_DOWN
} tstamp_scale_type_t;
/*
* Per-interface information.
*/
struct pcap_ng_if {
u_int tsresol; /* time stamp resolution */
u_int64_t tsoffset; /* time stamp offset */
tstamp_scale_type_t scale_type; /* how to scale */
};
struct pcap_ng_sf {
u_int user_tsresol; /* time stamp resolution requested by the user */
bpf_u_int32 ifcount; /* number of interfaces seen in this capture */
bpf_u_int32 ifaces_size; /* size of arrary below */
struct pcap_ng_if *ifaces; /* array of interface information */
};
static void pcap_ng_cleanup(pcap_t *p);
static int pcap_ng_next_packet(pcap_t *p, struct pcap_pkthdr *hdr,
u_char **data);
static int
read_bytes(FILE *fp, void *buf, size_t bytes_to_read, int fail_on_eof,
char *errbuf)
{
size_t amt_read;
amt_read = fread(buf, 1, bytes_to_read, fp);
if (amt_read != bytes_to_read) {
if (ferror(fp)) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"error reading dump file: %s",
pcap_strerror(errno));
} else {
if (amt_read == 0 && !fail_on_eof)
return (0); /* EOF */
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %lu bytes, only got %lu",
(unsigned long)bytes_to_read,
(unsigned long)amt_read);
}
return (-1);
}
return (1);
}
static int
read_block(FILE *fp, pcap_t *p, struct block_cursor *cursor, char *errbuf)
{
int status;
struct block_header bhdr;
status = read_bytes(fp, &bhdr, sizeof(bhdr), 0, errbuf);
if (status <= 0)
return (status); /* error or EOF */
if (p->swapped) {
bhdr.block_type = SWAPLONG(bhdr.block_type);
bhdr.total_length = SWAPLONG(bhdr.total_length);
}
/*
* Is this block "too big"?
*
* We choose 16MB as "too big", for now, so that we handle
* "reasonably" large buffers but don't chew up all the
* memory if we read a malformed file.
*/
if (bhdr.total_length > 16*1024*1024) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"pcap-ng block size %u > maximum %u",
bhdr.total_length, 16*1024*1024);
return (-1);
}
/*
* Is this block "too small" - i.e., is it shorter than a block
* header plus a block trailer?
*/
if (bhdr.total_length < sizeof(struct block_header) +
sizeof(struct block_trailer)) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"block in pcap-ng dump file has a length of %u < %lu",
bhdr.total_length,
(unsigned long)(sizeof(struct block_header) + sizeof(struct block_trailer)));
return (-1);
}
/*
* Is the buffer big enough?
*/
if (p->bufsize < bhdr.total_length) {
/*
* No - make it big enough.
*/
p->buffer = realloc(p->buffer, bhdr.total_length);
if (p->buffer == NULL) {
snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
return (-1);
}
}
/*
* Copy the stuff we've read to the buffer, and read the rest
* of the block.
*/
memcpy(p->buffer, &bhdr, sizeof(bhdr));
if (read_bytes(fp, p->buffer + sizeof(bhdr),
bhdr.total_length - sizeof(bhdr), 1, errbuf) == -1)
return (-1);
/*
* Initialize the cursor.
*/
cursor->data = p->buffer + sizeof(bhdr);
cursor->data_remaining = bhdr.total_length - sizeof(bhdr) -
sizeof(struct block_trailer);
cursor->block_type = bhdr.block_type;
return (1);
}
static void *
get_from_block_data(struct block_cursor *cursor, size_t chunk_size,
char *errbuf)
{
void *data;
/*
* Make sure we have the specified amount of data remaining in
* the block data.
*/
if (cursor->data_remaining < chunk_size) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"block of type %u in pcap-ng dump file is too short",
cursor->block_type);
return (NULL);
}
/*
* Return the current pointer, and skip past the chunk.
*/
data = cursor->data;
cursor->data += chunk_size;
cursor->data_remaining -= chunk_size;
return (data);
}
static struct option_header *
get_opthdr_from_block_data(pcap_t *p, struct block_cursor *cursor, char *errbuf)
{
struct option_header *opthdr;
opthdr = get_from_block_data(cursor, sizeof(*opthdr), errbuf);
if (opthdr == NULL) {
/*
* Option header is cut short.
*/
return (NULL);
}
/*
* Byte-swap it if necessary.
*/
if (p->swapped) {
opthdr->option_code = SWAPSHORT(opthdr->option_code);
opthdr->option_length = SWAPSHORT(opthdr->option_length);
}
return (opthdr);
}
static void *
get_optvalue_from_block_data(struct block_cursor *cursor,
struct option_header *opthdr, char *errbuf)
{
size_t padded_option_len;
void *optvalue;
/* Pad option length to 4-byte boundary */
padded_option_len = opthdr->option_length;
padded_option_len = ((padded_option_len + 3)/4)*4;
optvalue = get_from_block_data(cursor, padded_option_len, errbuf);
if (optvalue == NULL) {
/*
* Option value is cut short.
*/
return (NULL);
}
return (optvalue);
}
static int
process_idb_options(pcap_t *p, struct block_cursor *cursor, u_int *tsresol,
u_int64_t *tsoffset, char *errbuf)
{
struct option_header *opthdr;
void *optvalue;
int saw_tsresol, saw_tsoffset;
u_char tsresol_opt;
u_int i;
saw_tsresol = 0;
saw_tsoffset = 0;
while (cursor->data_remaining != 0) {
/*
* Get the option header.
*/
opthdr = get_opthdr_from_block_data(p, cursor, errbuf);
if (opthdr == NULL) {
/*
* Option header is cut short.
*/
return (-1);
}
/*
* Get option value.
*/
optvalue = get_optvalue_from_block_data(cursor, opthdr,
errbuf);
if (optvalue == NULL) {
/*
* Option value is cut short.
*/
return (-1);
}
switch (opthdr->option_code) {
case OPT_ENDOFOPT:
if (opthdr->option_length != 0) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Interface Description Block has opt_endofopt option with length %u != 0",
opthdr->option_length);
return (-1);
}
goto done;
case IF_TSRESOL:
if (opthdr->option_length != 1) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Interface Description Block has if_tsresol option with length %u != 1",
opthdr->option_length);
return (-1);
}
if (saw_tsresol) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Interface Description Block has more than one if_tsresol option");
return (-1);
}
saw_tsresol = 1;
memcpy(&tsresol_opt, optvalue, sizeof(tsresol_opt));
if (tsresol_opt & 0x80) {
/*
* Resolution is negative power of 2.
*/
*tsresol = 1 << (tsresol_opt & 0x7F);
} else {
/*
* Resolution is negative power of 10.
*/
*tsresol = 1;
for (i = 0; i < tsresol_opt; i++)
*tsresol *= 10;
}
if (*tsresol == 0) {
/*
* Resolution is too high.
*/
if (tsresol_opt & 0x80) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Interface Description Block if_tsresol option resolution 2^-%u is too high",
tsresol_opt & 0x7F);
} else {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Interface Description Block if_tsresol option resolution 10^-%u is too high",
tsresol_opt);
}
return (-1);
}
break;
case IF_TSOFFSET:
if (opthdr->option_length != 8) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Interface Description Block has if_tsoffset option with length %u != 8",
opthdr->option_length);
return (-1);
}
if (saw_tsoffset) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Interface Description Block has more than one if_tsoffset option");
return (-1);
}
saw_tsoffset = 1;
memcpy(tsoffset, optvalue, sizeof(*tsoffset));
if (p->swapped)
*tsoffset = SWAPLL(*tsoffset);
break;
default:
break;
}
}
done:
return (0);
}
static int
add_interface(pcap_t *p, struct block_cursor *cursor, char *errbuf)
{
struct pcap_ng_sf *ps;
u_int tsresol;
u_int64_t tsoffset;
ps = p->priv;
/*
* Count this interface.
*/
ps->ifcount++;
/*
* Grow the array of per-interface information as necessary.
*/
if (ps->ifcount > ps->ifaces_size) {
/*
* We need to grow the array.
*/
if (ps->ifaces == NULL) {
/*
* It's currently empty.
*/
ps->ifaces_size = 1;
ps->ifaces = malloc(sizeof (struct pcap_ng_if));
} else {
/*
* It's not currently empty; double its size.
* (Perhaps overkill once we have a lot of interfaces.)
*/
ps->ifaces_size *= 2;
ps->ifaces = realloc(ps->ifaces, ps->ifaces_size * sizeof (struct pcap_ng_if));
}
if (ps->ifaces == NULL) {
/*
* We ran out of memory.
* Give up.
*/
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"out of memory for per-interface information (%u interfaces)",
ps->ifcount);
return (0);
}
}
/*
* Set the default time stamp resolution and offset.
*/
tsresol = 1000000; /* microsecond resolution */
tsoffset = 0; /* absolute timestamps */
/*
* Now look for various time stamp options, so we know
* how to interpret the time stamps for this interface.
*/
if (process_idb_options(p, cursor, &tsresol, &tsoffset, errbuf) == -1)
return (0);
ps->ifaces[ps->ifcount - 1].tsresol = tsresol;
ps->ifaces[ps->ifcount - 1].tsoffset = tsoffset;
/*
* Determine whether we're scaling up or down or not
* at all for this interface.
*/
switch (p->opt.tstamp_precision) {
case PCAP_TSTAMP_PRECISION_MICRO:
if (tsresol == 1000000) {
/*
* The resolution is 1 microsecond,
* so we don't have to do scaling.
*/
ps->ifaces[ps->ifcount - 1].scale_type = PASS_THROUGH;
} else if (tsresol > 1000000) {
/*
* The resolution is greater than
* 1 microsecond, so we have to
* scale the timestamps down.
*/
ps->ifaces[ps->ifcount - 1].scale_type = SCALE_DOWN;
} else {
/*
* The resolution is less than 1
* microsecond, so we have to scale
* the timestamps up.
*/
ps->ifaces[ps->ifcount - 1].scale_type = SCALE_UP;
}
break;
case PCAP_TSTAMP_PRECISION_NANO:
if (tsresol == 1000000000) {
/*
* The resolution is 1 nanosecond,
* so we don't have to do scaling.
*/
ps->ifaces[ps->ifcount - 1].scale_type = PASS_THROUGH;
} else if (tsresol > 1000000000) {
/*
* The resolution is greater than
* 1 nanosecond, so we have to
* scale the timestamps down.
*/
ps->ifaces[ps->ifcount - 1].scale_type = SCALE_DOWN;
} else {
/*
* The resolution is less than 1
* nanosecond, so we have to scale
* the timestamps up.
*/
ps->ifaces[ps->ifcount - 1].scale_type = SCALE_UP;
}
break;
}
return (1);
}
/*
* Check whether this is a pcap-ng savefile and, if it is, extract the
* relevant information from the header.
*/
pcap_t *
pcap_ng_check_header(bpf_u_int32 magic, FILE *fp, u_int precision, char *errbuf,
int *err)
{
size_t amt_read;
bpf_u_int32 total_length;
bpf_u_int32 byte_order_magic;
struct block_header *bhdrp;
struct section_header_block *shbp;
pcap_t *p;
int swapped = 0;
struct pcap_ng_sf *ps;
int status;
struct block_cursor cursor;
struct interface_description_block *idbp;
/*
* Assume no read errors.
*/
*err = 0;
/*
* Check whether the first 4 bytes of the file are the block
* type for a pcap-ng savefile.
*/
if (magic != BT_SHB) {
/*
* XXX - check whether this looks like what the block
* type would be after being munged by mapping between
* UN*X and DOS/Windows text file format and, if it
* does, look for the byte-order magic number in
* the appropriate place and, if we find it, report
* this as possibly being a pcap-ng file transferred
* between UN*X and Windows in text file format?
*/
return (NULL); /* nope */
}
/*
* OK, they are. However, that's just \n\r\r\n, so it could,
* conceivably, be an ordinary text file.
*
* It could not, however, conceivably be any other type of
* capture file, so we can read the rest of the putative
* Section Header Block; put the block type in the common
* header, read the rest of the common header and the
* fixed-length portion of the SHB, and look for the byte-order
* magic value.
*/
amt_read = fread(&total_length, 1, sizeof(total_length), fp);
if (amt_read < sizeof(total_length)) {
if (ferror(fp)) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"error reading dump file: %s",
pcap_strerror(errno));
*err = 1;
return (NULL); /* fail */
}
/*
* Possibly a weird short text file, so just say
* "not pcap-ng".
*/
return (NULL);
}
amt_read = fread(&byte_order_magic, 1, sizeof(byte_order_magic), fp);
if (amt_read < sizeof(byte_order_magic)) {
if (ferror(fp)) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"error reading dump file: %s",
pcap_strerror(errno));
*err = 1;
return (NULL); /* fail */
}
/*
* Possibly a weird short text file, so just say
* "not pcap-ng".
*/
return (NULL);
}
if (byte_order_magic != BYTE_ORDER_MAGIC) {
byte_order_magic = SWAPLONG(byte_order_magic);
if (byte_order_magic != BYTE_ORDER_MAGIC) {
/*
* Not a pcap-ng file.
*/
return (NULL);
}
swapped = 1;
total_length = SWAPLONG(total_length);
}
/*
* Check the sanity of the total length.
*/
if (total_length < sizeof(*bhdrp) + sizeof(*shbp) + sizeof(struct block_trailer)) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"Section Header Block in pcap-ng dump file has a length of %u < %lu",
total_length,
(unsigned long)(sizeof(*bhdrp) + sizeof(*shbp) + sizeof(struct block_trailer)));
*err = 1;
return (NULL);
}
/*
* OK, this is a good pcap-ng file.
* Allocate a pcap_t for it.
*/
p = pcap_open_offline_common(errbuf, sizeof (struct pcap_ng_sf));
if (p == NULL) {
/* Allocation failed. */
*err = 1;
return (NULL);
}
p->swapped = swapped;
ps = p->priv;
/*
* What precision does the user want?
*/
switch (precision) {
case PCAP_TSTAMP_PRECISION_MICRO:
ps->user_tsresol = 1000000;
break;
case PCAP_TSTAMP_PRECISION_NANO:
ps->user_tsresol = 1000000000;
break;
default:
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"unknown time stamp resolution %u", precision);
free(p);
*err = 1;
return (NULL);
}
p->opt.tstamp_precision = precision;
/*
* Allocate a buffer into which to read blocks. We default to
* the maximum of:
*
* the total length of the SHB for which we read the header;
*
* 2K, which should be more than large enough for an Enhanced
* Packet Block containing a full-size Ethernet frame, and
* leaving room for some options.
*
* If we find a bigger block, we reallocate the buffer.
*/
p->bufsize = 2048;
if (p->bufsize < total_length)
p->bufsize = total_length;
p->buffer = malloc(p->bufsize);
if (p->buffer == NULL) {
snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
free(p);
*err = 1;
return (NULL);
}
/*
* Copy the stuff we've read to the buffer, and read the rest
* of the SHB.
*/
bhdrp = (struct block_header *)p->buffer;
shbp = (struct section_header_block *)(p->buffer + sizeof(struct block_header));
bhdrp->block_type = magic;
bhdrp->total_length = total_length;
shbp->byte_order_magic = byte_order_magic;
if (read_bytes(fp,
p->buffer + (sizeof(magic) + sizeof(total_length) + sizeof(byte_order_magic)),
total_length - (sizeof(magic) + sizeof(total_length) + sizeof(byte_order_magic)),
1, errbuf) == -1)
goto fail;
if (p->swapped) {
/*
* Byte-swap the fields we've read.
*/
shbp->major_version = SWAPSHORT(shbp->major_version);
shbp->minor_version = SWAPSHORT(shbp->minor_version);
/*
* XXX - we don't care about the section length.
*/
}
if (shbp->major_version != PCAP_NG_VERSION_MAJOR) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"unknown pcap-ng savefile major version number %u",
shbp->major_version);
goto fail;
}
p->version_major = shbp->major_version;
p->version_minor = shbp->minor_version;
/*
* Save the time stamp resolution the user requested.
*/
p->opt.tstamp_precision = precision;
/*
* Now start looking for an Interface Description Block.
*/
for (;;) {
/*
* Read the next block.
*/
status = read_block(fp, p, &cursor, errbuf);
if (status == 0) {
/* EOF - no IDB in this file */
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"the capture file has no Interface Description Blocks");
goto fail;
}
if (status == -1)
goto fail; /* error */
switch (cursor.block_type) {
case BT_IDB:
/*
* Get a pointer to the fixed-length portion of the
* IDB.
*/
idbp = get_from_block_data(&cursor, sizeof(*idbp),
errbuf);
if (idbp == NULL)
goto fail; /* error */
/*
* Byte-swap it if necessary.
*/
if (p->swapped) {
idbp->linktype = SWAPSHORT(idbp->linktype);
idbp->snaplen = SWAPLONG(idbp->snaplen);
}
/*
* Try to add this interface.
*/
if (!add_interface(p, &cursor, errbuf))
goto fail;
goto done;
case BT_EPB:
case BT_SPB:
case BT_PB:
/*
* Saw a packet before we saw any IDBs. That's
* not valid, as we don't know what link-layer
* encapsulation the packet has.
*/
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"the capture file has a packet block before any Interface Description Blocks");
goto fail;
default:
/*
* Just ignore it.
*/
break;
}
}
done:
p->tzoff = 0; /* XXX - not used in pcap */
p->snapshot = idbp->snaplen;
p->linktype = linktype_to_dlt(idbp->linktype);
p->linktype_ext = 0;
p->next_packet_op = pcap_ng_next_packet;
p->cleanup_op = pcap_ng_cleanup;
return (p);
fail:
free(ps->ifaces);
free(p->buffer);
free(p);
*err = 1;
return (NULL);
}
static void
pcap_ng_cleanup(pcap_t *p)
{
struct pcap_ng_sf *ps = p->priv;
free(ps->ifaces);
sf_cleanup(p);
}
/*
* 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_ng_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
{
struct pcap_ng_sf *ps = p->priv;
struct block_cursor cursor;
int status;
struct enhanced_packet_block *epbp;
struct simple_packet_block *spbp;
struct packet_block *pbp;
bpf_u_int32 interface_id = 0xFFFFFFFF;
struct interface_description_block *idbp;
struct section_header_block *shbp;
FILE *fp = p->rfile;
u_int64_t t, sec, frac;
/*
* Look for an Enhanced Packet Block, a Simple Packet Block,
* or a Packet Block.
*/
for (;;) {
/*
* Read the block type and length; those are common
* to all blocks.
*/
status = read_block(fp, p, &cursor, p->errbuf);
if (status == 0)
return (1); /* EOF */
if (status == -1)
return (-1); /* error */
switch (cursor.block_type) {
case BT_EPB:
/*
* Get a pointer to the fixed-length portion of the
* EPB.
*/
epbp = get_from_block_data(&cursor, sizeof(*epbp),
p->errbuf);
if (epbp == NULL)
return (-1); /* error */
/*
* Byte-swap it if necessary.
*/
if (p->swapped) {
/* these were written in opposite byte order */
interface_id = SWAPLONG(epbp->interface_id);
hdr->caplen = SWAPLONG(epbp->caplen);
hdr->len = SWAPLONG(epbp->len);
t = ((u_int64_t)SWAPLONG(epbp->timestamp_high)) << 32 |
SWAPLONG(epbp->timestamp_low);
} else {
interface_id = epbp->interface_id;
hdr->caplen = epbp->caplen;
hdr->len = epbp->len;
t = ((u_int64_t)epbp->timestamp_high) << 32 |
epbp->timestamp_low;
}
goto found;
case BT_SPB:
/*
* Get a pointer to the fixed-length portion of the
* SPB.
*/
spbp = get_from_block_data(&cursor, sizeof(*spbp),
p->errbuf);
if (spbp == NULL)
return (-1); /* error */
/*
* SPB packets are assumed to have arrived on
* the first interface.
*/
interface_id = 0;
/*
* Byte-swap it if necessary.
*/
if (p->swapped) {
/* these were written in opposite byte order */
hdr->len = SWAPLONG(spbp->len);
} else
hdr->len = spbp->len;
/*
* The SPB doesn't give the captured length;
* it's the minimum of the snapshot length
* and the packet length.
*/
hdr->caplen = hdr->len;
if (hdr->caplen > p->snapshot)
hdr->caplen = p->snapshot;
t = 0; /* no time stamps */
goto found;
case BT_PB:
/*
* Get a pointer to the fixed-length portion of the
* PB.
*/
pbp = get_from_block_data(&cursor, sizeof(*pbp),
p->errbuf);
if (pbp == NULL)
return (-1); /* error */
/*
* Byte-swap it if necessary.
*/
if (p->swapped) {
/* these were written in opposite byte order */
interface_id = SWAPSHORT(pbp->interface_id);
hdr->caplen = SWAPLONG(pbp->caplen);
hdr->len = SWAPLONG(pbp->len);
t = ((u_int64_t)SWAPLONG(pbp->timestamp_high)) << 32 |
SWAPLONG(pbp->timestamp_low);
} else {
interface_id = pbp->interface_id;
hdr->caplen = pbp->caplen;
hdr->len = pbp->len;
t = ((u_int64_t)pbp->timestamp_high) << 32 |
pbp->timestamp_low;
}
goto found;
case BT_IDB:
/*
* Interface Description Block. Get a pointer
* to its fixed-length portion.
*/
idbp = get_from_block_data(&cursor, sizeof(*idbp),
p->errbuf);
if (idbp == NULL)
return (-1); /* error */
/*
* Byte-swap it if necessary.
*/
if (p->swapped) {
idbp->linktype = SWAPSHORT(idbp->linktype);
idbp->snaplen = SWAPLONG(idbp->snaplen);
}
/*
* If the link-layer type or snapshot length
* differ from the ones for the first IDB we
* saw, quit.
*
* XXX - just discard packets from those
* interfaces?
*/
if (p->linktype != idbp->linktype) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"an interface has a type %u different from the type of the first interface",
idbp->linktype);
return (-1);
}
if (p->snapshot != idbp->snaplen) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"an interface has a snapshot length %u different from the type of the first interface",
idbp->snaplen);
return (-1);
}
/*
* Try to add this interface.
*/
if (!add_interface(p, &cursor, p->errbuf))
return (-1);
break;
case BT_SHB:
/*
* Section Header Block. Get a pointer
* to its fixed-length portion.
*/
shbp = get_from_block_data(&cursor, sizeof(*shbp),
p->errbuf);
if (shbp == NULL)
return (-1); /* error */
/*
* Assume the byte order of this section is
* the same as that of the previous section.
* We'll check for that later.
*/
if (p->swapped) {
shbp->byte_order_magic =
SWAPLONG(shbp->byte_order_magic);
shbp->major_version =
SWAPSHORT(shbp->major_version);
}
/*
* Make sure the byte order doesn't change;
* pcap_is_swapped() shouldn't change its
* return value in the middle of reading a capture.
*/
switch (shbp->byte_order_magic) {
case BYTE_ORDER_MAGIC:
/*
* OK.
*/
break;
case SWAPLONG(BYTE_ORDER_MAGIC):
/*
* Byte order changes.
*/
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"the file has sections with different byte orders");
return (-1);
default:
/*
* Not a valid SHB.
*/
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"the file has a section with a bad byte order magic field");
return (-1);
}
/*
* Make sure the major version is the version
* we handle.
*/
if (shbp->major_version != PCAP_NG_VERSION_MAJOR) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"unknown pcap-ng savefile major version number %u",
shbp->major_version);
return (-1);
}
/*
* Reset the interface count; this section should
* have its own set of IDBs. If any of them
* don't have the same interface type, snapshot
* length, or resolution as the first interface
* we saw, we'll fail. (And if we don't see
* any IDBs, we'll fail when we see a packet
* block.)
*/
ps->ifcount = 0;
break;
default:
/*
* Not a packet block, IDB, or SHB; ignore it.
*/
break;
}
}
found:
/*
* Is the interface ID an interface we know?
*/
if (interface_id >= ps->ifcount) {
/*
* Yes. Fail.
*/
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"a packet arrived on interface %u, but there's no Interface Description Block for that interface",
interface_id);
return (-1);
}
/*
* Convert the time stamp to seconds and fractions of a second,
* with the fractions being in units of the file-supplied resolution.
*/
sec = t / ps->ifaces[interface_id].tsresol + ps->ifaces[interface_id].tsoffset;
frac = t % ps->ifaces[interface_id].tsresol;
/*
* Convert the fractions from units of the file-supplied resolution
* to units of the user-requested resolution.
*/
switch (ps->ifaces[interface_id].scale_type) {
case PASS_THROUGH:
/*
* The interface resolution is what the user wants,
* so we're done.
*/
break;
case SCALE_UP:
case SCALE_DOWN:
/*
* The interface resolution is different from what the
* user wants; convert the fractions to units of the
* resolution the user requested by multiplying by the
* quotient of the user-requested resolution and the
* file-supplied resolution. We do that by multiplying
* by the user-requested resolution and dividing by the
* file-supplied resolution, as the quotient might not
* fit in an integer.
*
* XXX - if ps->ifaces[interface_id].tsresol is a power
* of 10, we could just multiply by the quotient of
* ps->user_tsresol and ps->ifaces[interface_id].tsresol
* in the scale-up case, and divide by the quotient of
* ps->ifaces[interface_id].tsresol and ps->user_tsresol
* in the scale-down case, as we know those will be integers.
* That would involve fewer arithmetic operations, and
* would run less risk of overflow.
*
* Is there something clever we could do if
* ps->ifaces[interface_id].tsresol is a power of 2?
*/
frac *= ps->user_tsresol;
frac /= ps->ifaces[interface_id].tsresol;
break;
}
hdr->ts.tv_sec = sec;
hdr->ts.tv_usec = frac;
/*
* Get a pointer to the packet data.
*/
*data = get_from_block_data(&cursor, hdr->caplen, p->errbuf);
if (*data == NULL)
return (-1);
if (p->swapped)
swap_pseudo_headers(p->linktype, hdr, *data);
return (0);
}