/src/libpcap-1.9.1/sf-pcapng.c

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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-pcapng.c - pcapng-file-format-specific code from savefile.c
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <pcap/pcap-inttypes.h>

#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-pcapng.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
#define BT_SHB_INSANE_MAX       1024U*1024U*1U  /* 1MB should be enough */
struct section_header_block {
  bpf_u_int32 byte_order_magic;
  u_short   major_version;
  u_short   minor_version;
  uint64_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
#define PCAP_NG_VERSION_MINOR 0

/*
 * 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_DEC,
  SCALE_DOWN_DEC,
  SCALE_UP_BIN,
  SCALE_DOWN_BIN
} tstamp_scale_type_t;

/*
 * Per-interface information.
 */
struct pcap_ng_if {
  uint64_t tsresol;   /* time stamp resolution */
  tstamp_scale_type_t scale_type; /* how to scale */
  uint64_t scale_factor;    /* time stamp scale factor for power-of-10 tsresol */
  uint64_t tsoffset;    /* time stamp offset */
};

/*
 * Per-pcap_t private data.
 *
 * max_blocksize is the maximum size of a block that we'll accept.  We
 * reject blocks bigger than this, so we don't consume too much memory
 * with a truly huge block.  It can change as we see IDBs with different
 * link-layer header types.  (Currently, we don't support IDBs with
 * different link-layer header types, but we will support it in the
 * future, when we offer file-reading APIs that support it.)
 *
 * XXX - that's an issue on ILP32 platforms, where the maximum block
 * size of 2^31-1 would eat all but one byte of the entire address space.
 * It's less of an issue on ILP64/LLP64 platforms, but the actual size
 * of the address space may be limited by 1) the number of *significant*
 * address bits (currently, x86-64 only supports 48 bits of address), 2)
 * any limitations imposed by the operating system; 3) any limitations
 * imposed by the amount of available backing store for anonymous pages,
 * so we impose a limit regardless of the size of a pointer.
 */
struct pcap_ng_sf {
  uint64_t user_tsresol;    /* time stamp resolution requested by the user */
  u_int max_blocksize;    /* don't grow buffer size past this */
  bpf_u_int32 ifcount;    /* number of interfaces seen in this capture */
  bpf_u_int32 ifaces_size;  /* size of array below */
  struct pcap_ng_if *ifaces;  /* array of interface information */
};

/*
 * The maximum block size we start with; we use an arbitrary value of
 * 16 MiB.
 */
#define INITIAL_MAX_BLOCKSIZE (16*1024*1024)

/*
 * Maximum block size for a given maximum snapshot length; we define it
 * as the size of an EPB with a max_snaplen-sized packet and 128KB of
 * options.
 */
#define MAX_BLOCKSIZE_FOR_SNAPLEN(max_snaplen) \
  (sizeof (struct block_header) + \
   sizeof (struct enhanced_packet_block) + \
   (max_snaplen) + 131072 + \
   sizeof (struct block_trailer))

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)) {
      pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
          errno, "error reading dump file");
    } else {
      if (amt_read == 0 && !fail_on_eof)
        return (0);  /* EOF */
      pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
          "truncated pcapng dump file; tried to read %" PRIsize " bytes, only got %" PRIsize,
          bytes_to_read, amt_read);
    }
    return (-1);
  }
  return (1);
}

static int
read_block(FILE *fp, pcap_t *p, struct block_cursor *cursor, char *errbuf)
{
  struct pcap_ng_sf *ps;
  int status;
  struct block_header bhdr;
  struct block_trailer *btrlr;
  u_char *bdata;
  size_t data_remaining;

  ps = p->priv;

  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 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)) {
    pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
        "block in pcapng dump file has a length of %u < %" PRIsize,
        bhdr.total_length,
        sizeof(struct block_header) + sizeof(struct block_trailer));
    return (-1);
  }

  /*
   * Is the block total length a multiple of 4?
   */
  if ((bhdr.total_length % 4) != 0) {
    /*
     * No.  Report that as an error.
     */
    pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
        "block in pcapng dump file has a length of %u that is not a multiple of 4" PRIsize,
        bhdr.total_length);
    return (-1);
  }

  /*
   * Is the buffer big enough?
   */
  if (p->bufsize < bhdr.total_length) {
    /*
     * No - make it big enough, unless it's too big, in
     * which case we fail.
     */
    void *bigger_buffer;

    if (bhdr.total_length > ps->max_blocksize) {
      pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "pcapng block size %u > maximum %u", bhdr.total_length,
          ps->max_blocksize);
      return (-1);
    }
    bigger_buffer = realloc(p->buffer, bhdr.total_length);
    if (bigger_buffer == NULL) {
      pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
      return (-1);
    }
    p->buffer = bigger_buffer;
  }

  /*
   * Copy the stuff we've read to the buffer, and read the rest
   * of the block.
   */
  memcpy(p->buffer, &bhdr, sizeof(bhdr));
  bdata = (u_char *)p->buffer + sizeof(bhdr);
  data_remaining = bhdr.total_length - sizeof(bhdr);
  if (read_bytes(fp, bdata, data_remaining, 1, errbuf) == -1)
    return (-1);

  /*
   * Get the block size from the trailer.
   */
  btrlr = (struct block_trailer *)(bdata + data_remaining - sizeof (struct block_trailer));
  if (p->swapped)
    btrlr->total_length = SWAPLONG(btrlr->total_length);

  /*
   * Is the total length from the trailer the same as the total
   * length from the header?
   */
  if (bhdr.total_length != btrlr->total_length) {
    /*
     * No.
     */
    pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
        "block total length in header and trailer don't match");
    return (-1);
  }

  /*
   * Initialize the cursor.
   */
  cursor->data = bdata;
  cursor->data_remaining = data_remaining - 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) {
    pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
        "block of type %u in pcapng 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, uint64_t *tsresol,
    uint64_t *tsoffset, int *is_binary, char *errbuf)
{
  struct option_header *opthdr;
  void *optvalue;
  int saw_tsresol, saw_tsoffset;
  uint8_t 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) {
        pcap_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) {
        pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
            "Interface Description Block has if_tsresol option with length %u != 1",
            opthdr->option_length);
        return (-1);
      }
      if (saw_tsresol) {
        pcap_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.
         */
        uint8_t tsresol_shift = (tsresol_opt & 0x7F);

        if (tsresol_shift > 63) {
          /*
           * Resolution is too high; 2^-{res}
           * won't fit in a 64-bit value.
           */
          pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
              "Interface Description Block if_tsresol option resolution 2^-%u is too high",
              tsresol_shift);
          return (-1);
        }
        *is_binary = 1;
        *tsresol = ((uint64_t)1) << tsresol_shift;
      } else {
        /*
         * Resolution is negative power of 10.
         */
        if (tsresol_opt > 19) {
          /*
           * Resolution is too high; 2^-{res}
           * won't fit in a 64-bit value (the
           * largest power of 10 that fits
           * in a 64-bit value is 10^19, as
           * the largest 64-bit unsigned
           * value is ~1.8*10^19).
           */
          pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
              "Interface Description Block if_tsresol option resolution 10^-%u is too high",
              tsresol_opt);
          return (-1);
        }
        *is_binary = 0;
        *tsresol = 1;
        for (i = 0; i < tsresol_opt; i++)
          *tsresol *= 10;
      }
      break;

    case IF_TSOFFSET:
      if (opthdr->option_length != 8) {
        pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
            "Interface Description Block has if_tsoffset option with length %u != 8",
            opthdr->option_length);
        return (-1);
      }
      if (saw_tsoffset) {
        pcap_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;
  uint64_t tsresol;
  uint64_t tsoffset;
  int is_binary;

  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.
     */
    bpf_u_int32 new_ifaces_size;
    struct pcap_ng_if *new_ifaces;

    if (ps->ifaces_size == 0) {
      /*
       * It's currently empty.
       *
       * (The Clang static analyzer doesn't do enough,
       * err, umm, dataflow *analysis* to realize that
       * ps->ifaces_size == 0 if ps->ifaces == NULL,
       * and so complains about a possible zero argument
       * to realloc(), so we check for the former
       * condition to shut it up.
       *
       * However, it doesn't complain that one of the
       * multiplications below could overflow, which is
       * a real, albeit extremely unlikely, problem (you'd
       * need a pcapng file with tens of millions of
       * interfaces).)
       */
      new_ifaces_size = 1;
      new_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.)
       *
       * Check for overflow if we double it.
       */
      if (ps->ifaces_size * 2 < ps->ifaces_size) {
        /*
         * The maximum number of interfaces before
         * ps->ifaces_size overflows is the largest
         * possible 32-bit power of 2, as we do
         * size doubling.
         */
        pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
            "more than %u interfaces in the file",
            0x80000000U);
        return (0);
      }

      /*
       * ps->ifaces_size * 2 doesn't overflow, so it's
       * safe to multiply.
       */
      new_ifaces_size = ps->ifaces_size * 2;

      /*
       * Now make sure that's not so big that it overflows
       * if we multiply by sizeof (struct pcap_ng_if).
       *
       * That can happen on 32-bit platforms, with a 32-bit
       * size_t; it shouldn't happen on 64-bit platforms,
       * with a 64-bit size_t, as new_ifaces_size is
       * 32 bits.
       */
      if (new_ifaces_size * sizeof (struct pcap_ng_if) < new_ifaces_size) {
        /*
         * As this fails only with 32-bit size_t,
         * the multiplication was 32x32->32, and
         * the largest 32-bit value that can safely
         * be multiplied by sizeof (struct pcap_ng_if)
         * without overflow is the largest 32-bit
         * (unsigned) value divided by
         * sizeof (struct pcap_ng_if).
         */
        pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
            "more than %u interfaces in the file",
            0xFFFFFFFFU / ((u_int)sizeof (struct pcap_ng_if)));
        return (0);
      }
      new_ifaces = realloc(ps->ifaces, new_ifaces_size * sizeof (struct pcap_ng_if));
    }
    if (new_ifaces == NULL) {
      /*
       * We ran out of memory.
       * Give up.
       */
      pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
          "out of memory for per-interface information (%u interfaces)",
          ps->ifcount);
      return (0);
    }
    ps->ifaces_size = new_ifaces_size;
    ps->ifaces = new_ifaces;
  }

  /*
   * Set the default time stamp resolution and offset.
   */
  tsresol = 1000000;  /* microsecond resolution */
  is_binary = 0;    /* which is a power of 10 */
  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, &is_binary,
      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.
   */
  if (tsresol == ps->user_tsresol) {
    /*
     * The resolution is the resolution the user wants,
     * so we don't have to do scaling.
     */
    ps->ifaces[ps->ifcount - 1].scale_type = PASS_THROUGH;
  } else if (tsresol > ps->user_tsresol) {
    /*
     * The resolution is greater than what the user wants,
     * so we have to scale the timestamps down.
     */
    if (is_binary)
      ps->ifaces[ps->ifcount - 1].scale_type = SCALE_DOWN_BIN;
    else {
      /*
       * Calculate the scale factor.
       */
      ps->ifaces[ps->ifcount - 1].scale_factor = tsresol/ps->user_tsresol;
      ps->ifaces[ps->ifcount - 1].scale_type = SCALE_DOWN_DEC;
    }
  } else {
    /*
     * The resolution is less than what the user wants,
     * so we have to scale the timestamps up.
     */
    if (is_binary)
      ps->ifaces[ps->ifcount - 1].scale_type = SCALE_UP_BIN;
    else {
      /*
       * Calculate the scale factor.
       */
      ps->ifaces[ps->ifcount - 1].scale_factor = ps->user_tsresol/tsresol;
      ps->ifaces[ps->ifcount - 1].scale_type = SCALE_UP_DEC;
    }
  }
  return (1);
}

/*
 * Check whether this is a pcapng savefile and, if it is, extract the
 * relevant information from the header.
 */
pcap_t *
pcap_ng_check_header(const uint8_t *magic, FILE *fp, u_int precision,
    char *errbuf, int *err)
{
  bpf_u_int32 magic_int;
  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 pcapng savefile.
   */
  memcpy(&magic_int, magic, sizeof(magic_int));
  if (magic_int != 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 pcapng 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)) {
      pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
          errno, "error reading dump file");
      *err = 1;
      return (NULL);  /* fail */
    }

    /*
     * Possibly a weird short text file, so just say
     * "not pcapng".
     */
    return (NULL);
  }
  amt_read = fread(&byte_order_magic, 1, sizeof(byte_order_magic), fp);
  if (amt_read < sizeof(byte_order_magic)) {
    if (ferror(fp)) {
      pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
          errno, "error reading dump file");
      *err = 1;
      return (NULL);  /* fail */
    }

    /*
     * Possibly a weird short text file, so just say
     * "not pcapng".
     */
    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 pcapng 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) ||
            (total_length > BT_SHB_INSANE_MAX)) {
    pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
        "Section Header Block in pcapng dump file has invalid length %" PRIsize " < _%u_ < %u (BT_SHB_INSANE_MAX)",
        sizeof(*bhdrp) + sizeof(*shbp) + sizeof(struct block_trailer),
        total_length,
        BT_SHB_INSANE_MAX);

    *err = 1;
    return (NULL);
  }

  /*
   * OK, this is a good pcapng 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:
    pcap_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, up to
   * the maximum size.  We start out with a maximum size of
   * INITIAL_MAX_BLOCKSIZE; if we see any link-layer header types
   * with a maximum snapshot that results in a larger maximum
   * block length, we boost the maximum.
   */
  p->bufsize = 2048;
  if (p->bufsize < total_length)
    p->bufsize = total_length;
  p->buffer = malloc(p->bufsize);
  if (p->buffer == NULL) {
    pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
    free(p);
    *err = 1;
    return (NULL);
  }
  ps->max_blocksize = INITIAL_MAX_BLOCKSIZE;

  /*
   * 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 *)((u_char *)p->buffer + sizeof(struct block_header));
  bhdrp->block_type = magic_int;
  bhdrp->total_length = total_length;
  shbp->byte_order_magic = byte_order_magic;
  if (read_bytes(fp,
      (u_char *)p->buffer + (sizeof(magic_int) + sizeof(total_length) + sizeof(byte_order_magic)),
      total_length - (sizeof(magic_int) + 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.
     */
  }
  /* currently only SHB version 1.0 is supported */
  if (! (shbp->major_version == PCAP_NG_VERSION_MAJOR &&
         shbp->minor_version == PCAP_NG_VERSION_MINOR)) {
    pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
        "unsupported pcapng savefile version %u.%u",
        shbp->major_version, shbp->minor_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 */
      pcap_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.
       */
      pcap_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->linktype = linktype_to_dlt(idbp->linktype);
  p->snapshot = pcap_adjust_snapshot(p->linktype, idbp->snaplen);
  p->linktype_ext = 0;

  /*
   * If the maximum block size for a packet with the maximum
   * snapshot length for this DLT_ is bigger than the current
   * maximum block size, increase the maximum.
   */
  if (MAX_BLOCKSIZE_FOR_SNAPLEN(max_snaplen_for_dlt(p->linktype)) > ps->max_blocksize)
    ps->max_blocksize = MAX_BLOCKSIZE_FOR_SNAPLEN(max_snaplen_for_dlt(p->linktype));

  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;
  uint64_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 = ((uint64_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 = ((uint64_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 > (bpf_u_int32)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 = ((uint64_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 = ((uint64_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) {
        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
            "an interface has a type %u different from the type of the first interface",
            idbp->linktype);
        return (-1);
      }

      /*
       * Check against the *adjusted* value of this IDB's
       * snapshot length.
       */
      if ((bpf_u_int32)p->snapshot !=
          pcap_adjust_snapshot(p->linktype, idbp->snaplen)) {
        pcap_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.
         */
        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
            "the file has sections with different byte orders");
        return (-1);

      default:
        /*
         * Not a valid SHB.
         */
        pcap_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) {
        pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
            "unknown pcapng 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.
     */
    pcap_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);
  }

  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);
    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_DEC:
    /*
     * The interface resolution is less than what the user
     * wants; scale the fractional part up to the units of
     * the resolution the user requested by multiplying by
     * the quotient of the user-requested resolution and the
     * file-supplied resolution.
     *
     * Those resolutions are both powers of 10, and the user-
     * requested resolution is greater than the file-supplied
     * resolution, so the quotient in question is an integer.
     * We've calculated that quotient already, so we just
     * multiply by it.
     */
    frac *= ps->ifaces[interface_id].scale_factor;
    break;

  case SCALE_UP_BIN:
    /*
     * The interface resolution is less than what the user
     * wants; scale the fractional part up to the units of
     * the resolution the user requested by multiplying by
     * the quotient of the user-requested resolution and the
     * file-supplied resolution.
     *
     * The file-supplied resolution is a power of 2, so the
     * quotient is not an integer, so, in order to do this
     * entirely with integer arithmetic, we multiply by the
     * user-requested resolution and divide by the file-
     * supplied resolution.
     *
     * XXX - Is there something clever we could do here,
     * given that we know that the file-supplied resolution
     * is a power of 2?  Doing a multiplication followed by
     * a division runs the risk of overflowing, and involves
     * two non-simple arithmetic operations.
     */
    frac *= ps->user_tsresol;
    frac /= ps->ifaces[interface_id].tsresol;
    break;

  case SCALE_DOWN_DEC:
    /*
     * The interface resolution is greater than what the user
     * wants; scale the fractional part up to the units of
     * the resolution the user requested by multiplying by
     * the quotient of the user-requested resolution and the
     * file-supplied resolution.
     *
     * Those resolutions are both powers of 10, and the user-
     * requested resolution is less than the file-supplied
     * resolution, so the quotient in question isn't an
     * integer, but its reciprocal is, and we can just divide
     * by the reciprocal of the quotient.  We've calculated
     * the reciprocal of that quotient already, so we must
     * divide by it.
     */
    frac /= ps->ifaces[interface_id].scale_factor;
    break;


  case SCALE_DOWN_BIN:
    /*
     * The interface resolution is greater than what the user
     * wants; convert the fractional part 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.
     *
     * The file-supplied resolution is a power of 2, so the
     * quotient is not an integer, and neither is its
     * reciprocal, so, in order to do this entirely with
     * integer arithmetic, we multiply by the user-requested
     * resolution and divide by the file-supplied resolution.
     *
     * XXX - Is there something clever we could do here,
     * given that we know that the file-supplied resolution
     * is a power of 2?  Doing a multiplication followed by
     * a division runs the risk of overflowing, and involves
     * two non-simple arithmetic operations.
     */
    frac *= ps->user_tsresol;
    frac /= ps->ifaces[interface_id].tsresol;
    break;
  }
#ifdef _WIN32
  /*
   * tv_sec and tv_used in the Windows struct timeval are both
   * longs.
   */
  hdr->ts.tv_sec = (long)sec;
  hdr->ts.tv_usec = (long)frac;
#else
  /*
   * tv_sec in the UN*X struct timeval is a time_t; tv_usec is
   * suseconds_t in UN*Xes that work the way the current Single
   * UNIX Standard specify - but not all older UN*Xes necessarily
   * support that type, so just cast to int.
   */
  hdr->ts.tv_sec = (time_t)sec;
  hdr->ts.tv_usec = (int)frac;
#endif

  /*
   * 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);
}

Coverage Report

Created: 2025-07-23 07:29