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capture_loop.c

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/* capture_loop.c
 * The actual capturing loop, getting packets and storing it
 *
 * $Id: capture_loop.c 19456 2006-10-08 22:39:23Z ulfl $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */


/** @file
 *
 * Capture loop (internal interface).
 *
 * It will open the input and output files, capture the packets,
 * change ringbuffer output files while capturing and close all files again.
 *
 * The input file can be a network interface or capture pipe (unix only).
 * The output file can be a single or a ringbuffer file handled by wiretap.
 *
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef HAVE_LIBPCAP

#include <string.h>

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif

#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif

#include <signal.h>
#include <errno.h>
#include <setjmp.h>


#include <glib.h>

#include <pcap.h>

#include "pcapio.h"

#include "capture-pcap-util.h"

#include "capture.h"
#include "capture_sync.h"

#include "conditions.h"
#include "capture_stop_conditions.h"
#include "ringbuffer.h"

#include "simple_dialog.h"
#include "tempfile.h"
#include "log.h"
#include "file_util.h"

#include "epan/unicode-utils.h"

#include "capture_loop.h"

/*
 * Standard secondary message for unexpected errors.
 */
static const char please_report[] =
    "Please report this to the Wireshark developers.  (This is not a crash;\n"
    "please do not report it as such.)";

/*
 * This needs to be static, so that the SIGUSR1 handler can clear the "go"
 * flag.
 */
static loop_data   ld;


/*
 * Timeout, in milliseconds, for reads from the stream of captured packets.
 */
#define     CAP_READ_TIMEOUT  250
static char *cap_pipe_err_str;

static void capture_loop_packet_cb(u_char *user, const struct pcap_pkthdr *phdr,
  const u_char *pd);
static void capture_loop_get_errmsg(char *errmsg, int errmsglen, const char *fname,
                    int err, gboolean is_close);



/* Take care of byte order in the libpcap headers read from pipes.
 * (function taken from wiretap/libpcap.c) */
static void
cap_pipe_adjust_header(gboolean byte_swapped, struct pcap_hdr *hdr, struct pcaprec_hdr *rechdr)
{
  if (byte_swapped) {
    /* Byte-swap the record header fields. */
    rechdr->ts_sec = BSWAP32(rechdr->ts_sec);
    rechdr->ts_usec = BSWAP32(rechdr->ts_usec);
    rechdr->incl_len = BSWAP32(rechdr->incl_len);
    rechdr->orig_len = BSWAP32(rechdr->orig_len);
  }

  /* In file format version 2.3, the "incl_len" and "orig_len" fields were
     swapped, in order to match the BPF header layout.

     Unfortunately, some files were, according to a comment in the "libpcap"
     source, written with version 2.3 in their headers but without the
     interchanged fields, so if "incl_len" is greater than "orig_len" - which
     would make no sense - we assume that we need to swap them.  */
  if (hdr->version_major == 2 &&
      (hdr->version_minor < 3 ||
       (hdr->version_minor == 3 && rechdr->incl_len > rechdr->orig_len))) {
    guint32 temp;

    temp = rechdr->orig_len;
    rechdr->orig_len = rechdr->incl_len;
    rechdr->incl_len = temp;
  }
}

/* Provide select() functionality for a single file descriptor
 * on both UNIX/POSIX and Windows.
 *
 * The Windows version calls WaitForSingleObject instead of
 * select().
 *
 * Returns the same values as select.  If an error is returned,
 * the string cap_pipe_err_str should be used instead of errno.
 */
static int
cap_pipe_select(int pipe_fd, gboolean wait_forever) {
#ifndef _WIN32
  fd_set      rfds;
  struct timeval timeout, *pto;
  int sel_ret;

  cap_pipe_err_str = "Unknown error";

  FD_ZERO(&rfds);
  FD_SET(pipe_fd, &rfds);
  if (wait_forever) {
    pto = NULL;
  } else {
    timeout.tv_sec = 0;
    timeout.tv_usec = CAP_READ_TIMEOUT * 1000;
    pto = &timeout;
  }
  sel_ret = select(pipe_fd+1, &rfds, NULL, NULL, pto);
  if (sel_ret < 0)
    cap_pipe_err_str = strerror(errno);
  return sel_ret;
}
#else
  /* XXX - Should we just use file handles exclusively under Windows?
   * Otherwise we have to convert between file handles and file descriptors
   * here and when we open a named pipe.
   */
  HANDLE hPipe = (HANDLE) _get_osfhandle(pipe_fd);
  wchar_t *err_str;
  DWORD timeout = wait_forever ? INFINITE : CAP_READ_TIMEOUT * 1000;
  DWORD wait_ret;

  if (hPipe == INVALID_HANDLE_VALUE) {
    cap_pipe_err_str = "Could not open standard input";
    return -1;
  }

  cap_pipe_err_str = "Unknown error";

  wait_ret = WaitForSingleObject(hPipe, timeout);
  switch (wait_ret) {
    /* XXX - This probably isn't correct */
    case WAIT_ABANDONED:
      errno = EINTR;
      return -1;
    case WAIT_OBJECT_0:
      return 1;
    case WAIT_TIMEOUT:
      return 0;
    case WAIT_FAILED:
      FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
        NULL, GetLastError(), 0, (LPTSTR) &err_str, 0, NULL);
      cap_pipe_err_str = utf_16to8(err_str);
      LocalFree(err_str);
      return -1;
    default:
      g_assert_not_reached();
      return -1;
  }
}
#endif


/* Mimic pcap_open_live() for pipe captures
 * We check if "pipename" is "-" (stdin) or a FIFO, open it, and read the
 * header.
 * N.B. : we can't read the libpcap formats used in RedHat 6.1 or SuSE 6.3
 * because we can't seek on pipes (see wiretap/libpcap.c for details) */
static int
cap_pipe_open_live(char *pipename, struct pcap_hdr *hdr, loop_data *ld,
                 char *errmsg, int errmsgl)
{
#ifndef _WIN32
  struct stat pipe_stat;
#else
#if 0
  char *pncopy, *pos;
  wchar_t *err_str;
#endif
  HANDLE hPipe = NULL;
#endif
  int          sel_ret;
  int          fd;
  int          b;
  guint32       magic;
  unsigned int bytes_read;

  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "cap_pipe_open_live: %s", pipename);

  /*
   * XXX (T)Wireshark blocks until we return
   */
  if (strcmp(pipename, "-") == 0) {
    fd = 0; /* read from stdin */
#ifdef _WIN32
    /*
     * This is needed to set the stdin pipe into binary mode, otherwise
     * CR/LF are mangled...
     */
    _setmode(0, _O_BINARY);
#endif  /* _WIN32 */
  } else {
#ifndef _WIN32
    if (eth_stat(pipename, &pipe_stat) < 0) {
      if (errno == ENOENT || errno == ENOTDIR)
        ld->cap_pipe_err = PIPNEXIST;
      else {
        g_snprintf(errmsg, errmsgl,
          "The capture session could not be initiated "
          "due to error on pipe: %s", strerror(errno));
        ld->cap_pipe_err = PIPERR;
      }
      return -1;
    }
    if (! S_ISFIFO(pipe_stat.st_mode)) {
      if (S_ISCHR(pipe_stat.st_mode)) {
        /*
         * Assume the user specified an interface on a system where
         * interfaces are in /dev.  Pretend we haven't seen it.
         */
         ld->cap_pipe_err = PIPNEXIST;
      } else
      {
        g_snprintf(errmsg, errmsgl,
            "The capture session could not be initiated because\n"
            "\"%s\" is neither an interface nor a pipe", pipename);
        ld->cap_pipe_err = PIPERR;
      }
      return -1;
    }
    fd = eth_open(pipename, O_RDONLY | O_NONBLOCK, 0000 /* no creation so don't matter */);
    if (fd == -1) {
      g_snprintf(errmsg, errmsgl,
          "The capture session could not be initiated "
          "due to error on pipe open: %s", strerror(errno));
      ld->cap_pipe_err = PIPERR;
      return -1;
    }
#else /* _WIN32 */
#if 0 /* Enable/disable Windows named pipes */
#define PIPE_STR "\\pipe\\"
    /* Under Windows, named pipes _must_ have the form
     * "\<server>\pipe<pipename>".  <server> may be "." for localhost.
     */
    pncopy = g_strdup(pipename);
    if (strstr(pncopy, "\\\\") == pncopy) {
      pos = strchr(pncopy + 3, '\\');
      if (pos && g_strncasecmp(pos, PIPE_STR, strlen(PIPE_STR)) != 0)
        pos = NULL;
    }

    g_free(pncopy);

    if (!pos) {
      g_snprintf(errmsg, errmsgl,
          "The capture session could not be initiated because\n"
          "\"%s\" is neither an interface nor a pipe", pipename);
      ld->cap_pipe_err = PIPNEXIST;
      return -1;
    }

    /* Wait for the pipe to appear */
    while (1) {
      hPipe = CreateFile(utf_8to16(pipename), GENERIC_READ, 0, NULL,
          OPEN_EXISTING, 0, NULL);

      if (hPipe != INVALID_HANDLE_VALUE)
        break;

      if (GetLastError() != ERROR_PIPE_BUSY) {
        FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
          NULL, GetLastError(), 0, (LPTSTR) &err_str, 0, NULL);
        g_snprintf(errmsg, errmsgl,
            "The capture session on \"%s\" could not be initiated "
            "due to error on pipe open: pipe busy: %s (error %d)",
          pipename, utf_16to8(err_str), GetLastError());
        LocalFree(err_str);
        ld->cap_pipe_err = PIPERR;
        return -1;
      }

      if (!WaitNamedPipe(utf_8to16(pipename), 30 * 1000)) {
        FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
          NULL, GetLastError(), 0, (LPTSTR) &err_str, 0, NULL);
        g_snprintf(errmsg, errmsgl,
            "The capture session could not be initiated "
            "due to error on pipe open: %s (error %d)",
          utf_16to8(err_str), GetLastError());
        LocalFree(err_str);
        ld->cap_pipe_err = PIPERR;
        return -1;
      }
    }

    fd = _open_osfhandle((long) hPipe, _O_RDONLY);
    if (fd == -1) {
      g_snprintf(errmsg, errmsgl,
          "The capture session could not be initiated "
          "due to error on pipe open: %s", strerror(errno));
      ld->cap_pipe_err = PIPERR;
      return -1;
    }
#else /* Enable/disable Windows named pipes */
    /* On Windows, we don't support capturing on pipes, so we give up. */

    g_snprintf(errmsg, errmsgl,
"The capture session could not be initiated.  Unable to open interface.");
    return -1;
#endif /* Enable/disable Windows named pipes */
#endif /* _WIN32 */
  }

  ld->from_cap_pipe = TRUE;

  /* read the pcap header */
  bytes_read = 0;
  while (bytes_read < sizeof magic) {
    sel_ret = cap_pipe_select(fd, FALSE);
    if (sel_ret < 0) {
      g_snprintf(errmsg, errmsgl,
        "Unexpected error from select: %s", strerror(errno));
      goto error;
    } else if (sel_ret > 0) {
      b = read(fd, ((char *)&magic)+bytes_read, sizeof magic-bytes_read);
      if (b <= 0) {
        if (b == 0)
          g_snprintf(errmsg, errmsgl, "End of file on pipe during open");
        else
          g_snprintf(errmsg, errmsgl, "Error on pipe during open: %s",
            strerror(errno));
        goto error;
      }
      bytes_read += b;
    }
  }

  switch (magic) {
  case PCAP_MAGIC:
    /* Host that wrote it has our byte order, and was running
       a program using either standard or ss990417 libpcap. */
    ld->cap_pipe_byte_swapped = FALSE;
    ld->cap_pipe_modified = FALSE;
    break;
  case PCAP_MODIFIED_MAGIC:
    /* Host that wrote it has our byte order, but was running
       a program using either ss990915 or ss991029 libpcap. */
    ld->cap_pipe_byte_swapped = FALSE;
    ld->cap_pipe_modified = TRUE;
    break;
  case PCAP_SWAPPED_MAGIC:
    /* Host that wrote it has a byte order opposite to ours,
       and was running a program using either standard or
       ss990417 libpcap. */
    ld->cap_pipe_byte_swapped = TRUE;
    ld->cap_pipe_modified = FALSE;
    break;
  case PCAP_SWAPPED_MODIFIED_MAGIC:
    /* Host that wrote it out has a byte order opposite to
       ours, and was running a program using either ss990915
       or ss991029 libpcap. */
    ld->cap_pipe_byte_swapped = TRUE;
    ld->cap_pipe_modified = TRUE;
    break;
  default:
    /* Not a "libpcap" type we know about. */
    g_snprintf(errmsg, errmsgl, "Unrecognized libpcap format");
    goto error;
  }

  /* Read the rest of the header */
  bytes_read = 0;
  while (bytes_read < sizeof(struct pcap_hdr)) {
    sel_ret = cap_pipe_select(fd, FALSE);
    if (sel_ret < 0) {
      g_snprintf(errmsg, errmsgl,
        "Unexpected error from select: %s", strerror(errno));
      goto error;
    } else if (sel_ret > 0) {
      b = read(fd, ((char *)hdr)+bytes_read,
            sizeof(struct pcap_hdr) - bytes_read);
      if (b <= 0) {
        if (b == 0)
          g_snprintf(errmsg, errmsgl, "End of file on pipe during open");
        else
          g_snprintf(errmsg, errmsgl, "Error on pipe during open: %s",
            strerror(errno));
        goto error;
      }
      bytes_read += b;
    }
  }

  if (ld->cap_pipe_byte_swapped) {
    /* Byte-swap the header fields about which we care. */
    hdr->version_major = BSWAP16(hdr->version_major);
    hdr->version_minor = BSWAP16(hdr->version_minor);
    hdr->snaplen = BSWAP32(hdr->snaplen);
    hdr->network = BSWAP32(hdr->network);
  }
  ld->linktype = hdr->network;

  if (hdr->version_major < 2) {
    g_snprintf(errmsg, errmsgl, "Unable to read old libpcap format");
    goto error;
  }

  ld->cap_pipe_state = STATE_EXPECT_REC_HDR;
  ld->cap_pipe_err = PIPOK;
  return fd;

error:
  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "cap_pipe_open_live: error %s", errmsg);
  ld->cap_pipe_err = PIPERR;
  eth_close(fd);
  return -1;

}


/* We read one record from the pipe, take care of byte order in the record
 * header, write the record to the capture file, and update capture statistics. */
static int
cap_pipe_dispatch(loop_data *ld, guchar *data, char *errmsg, int errmsgl)
{
  struct pcap_pkthdr phdr;
  int b;
  enum { PD_REC_HDR_READ, PD_DATA_READ, PD_PIPE_EOF, PD_PIPE_ERR,
          PD_ERR } result;


#ifdef LOG_CAPTURE_VERBOSE
  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "cap_pipe_dispatch");
#endif

  switch (ld->cap_pipe_state) {

  case STATE_EXPECT_REC_HDR:
    ld->cap_pipe_bytes_to_read = ld->cap_pipe_modified ?
      sizeof(struct pcaprec_modified_hdr) : sizeof(struct pcaprec_hdr);
    ld->cap_pipe_bytes_read = 0;
    ld->cap_pipe_state = STATE_READ_REC_HDR;
    /* Fall through */

  case STATE_READ_REC_HDR:
    b = read(ld->cap_pipe_fd, ((char *)&ld->cap_pipe_rechdr)+ld->cap_pipe_bytes_read,
             ld->cap_pipe_bytes_to_read - ld->cap_pipe_bytes_read);
    if (b <= 0) {
      if (b == 0)
        result = PD_PIPE_EOF;
      else
        result = PD_PIPE_ERR;
      break;
    }
    if ((ld->cap_pipe_bytes_read += b) < ld->cap_pipe_bytes_to_read)
        return 0;
    result = PD_REC_HDR_READ;
    break;

  case STATE_EXPECT_DATA:
    ld->cap_pipe_bytes_read = 0;
    ld->cap_pipe_state = STATE_READ_DATA;
    /* Fall through */

  case STATE_READ_DATA:
    b = read(ld->cap_pipe_fd, data+ld->cap_pipe_bytes_read,
             ld->cap_pipe_rechdr.hdr.incl_len - ld->cap_pipe_bytes_read);
    if (b <= 0) {
      if (b == 0)
        result = PD_PIPE_EOF;
      else
        result = PD_PIPE_ERR;
      break;
    }
    if ((ld->cap_pipe_bytes_read += b) < ld->cap_pipe_rechdr.hdr.incl_len)
      return 0;
    result = PD_DATA_READ;
    break;

  default:
    g_snprintf(errmsg, errmsgl, "cap_pipe_dispatch: invalid state");
    result = PD_ERR;

  } /* switch (ld->cap_pipe_state) */

  /*
   * We've now read as much data as we were expecting, so process it.
   */
  switch (result) {

  case PD_REC_HDR_READ:
    /* We've read the header. Take care of byte order. */
    cap_pipe_adjust_header(ld->cap_pipe_byte_swapped, &ld->cap_pipe_hdr,
                           &ld->cap_pipe_rechdr.hdr);
    if (ld->cap_pipe_rechdr.hdr.incl_len > WTAP_MAX_PACKET_SIZE) {
      g_snprintf(errmsg, errmsgl, "Frame %u too long (%d bytes)",
        ld->packet_count+1, ld->cap_pipe_rechdr.hdr.incl_len);
      break;
    }
    ld->cap_pipe_state = STATE_EXPECT_DATA;
    return 0;

  case PD_DATA_READ:
    /* Fill in a "struct pcap_pkthdr", and process the packet. */
    phdr.ts.tv_sec = ld->cap_pipe_rechdr.hdr.ts_sec;
    phdr.ts.tv_usec = ld->cap_pipe_rechdr.hdr.ts_usec;
    phdr.caplen = ld->cap_pipe_rechdr.hdr.incl_len;
    phdr.len = ld->cap_pipe_rechdr.hdr.orig_len;

    ld->packet_cb((u_char *)ld, &phdr, data);

    ld->cap_pipe_state = STATE_EXPECT_REC_HDR;
    return 1;

  case PD_PIPE_EOF:
    ld->cap_pipe_err = PIPEOF;
    return -1;

  case PD_PIPE_ERR:
    g_snprintf(errmsg, errmsgl, "Error reading from pipe: %s",
      strerror(errno));
    /* Fall through */
  case PD_ERR:
    break;
  }

  ld->cap_pipe_err = PIPERR;
  /* Return here rather than inside the switch to prevent GCC warning */
  return -1;
}


/* open the capture input file (pcap or capture pipe) */
gboolean
capture_loop_open_input(capture_options *capture_opts, loop_data *ld,
                        char *errmsg, size_t errmsg_len,
                        char *secondary_errmsg, size_t secondary_errmsg_len)
{
  gchar       open_err_str[PCAP_ERRBUF_SIZE];
  gchar      *sync_msg_str;
  static const char ppamsg[] = "can't find PPA for ";
  const char *set_linktype_err_str;
  const char  *libpcap_warn;
#ifdef _WIN32
  gchar      *sync_secondary_msg_str;
  int         err;
  WORD        wVersionRequested;
  WSADATA     wsaData;
#endif


  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_open_input : %s", capture_opts->iface);


/* XXX - opening Winsock on tshark? */

  /* Initialize Windows Socket if we are in a WIN32 OS
     This needs to be done before querying the interface for network/netmask */
#ifdef _WIN32
  /* XXX - do we really require 1.1 or earlier?
     Are there any versions that support only 2.0 or higher? */
  wVersionRequested = MAKEWORD(1, 1);
  err = WSAStartup(wVersionRequested, &wsaData);
  if (err != 0) {
    switch (err) {

    case WSASYSNOTREADY:
      g_snprintf(errmsg, errmsg_len,
        "Couldn't initialize Windows Sockets: Network system not ready for network communication");
      break;

    case WSAVERNOTSUPPORTED:
      g_snprintf(errmsg, errmsg_len,
        "Couldn't initialize Windows Sockets: Windows Sockets version %u.%u not supported",
        LOBYTE(wVersionRequested), HIBYTE(wVersionRequested));
      break;

    case WSAEINPROGRESS:
      g_snprintf(errmsg, errmsg_len,
        "Couldn't initialize Windows Sockets: Blocking operation is in progress");
      break;

    case WSAEPROCLIM:
      g_snprintf(errmsg, errmsg_len,
        "Couldn't initialize Windows Sockets: Limit on the number of tasks supported by this WinSock implementation has been reached");
      break;

    case WSAEFAULT:
      g_snprintf(errmsg, errmsg_len,
        "Couldn't initialize Windows Sockets: Bad pointer passed to WSAStartup");
      break;

    default:
      g_snprintf(errmsg, errmsg_len,
        "Couldn't initialize Windows Sockets: error %d", err);
      break;
    }
    g_snprintf(secondary_errmsg, secondary_errmsg_len, please_report);
    return FALSE;
  }
#endif

  /* Open the network interface to capture from it.
     Some versions of libpcap may put warnings into the error buffer
     if they succeed; to tell if that's happened, we have to clear
     the error buffer, and check if it's still a null string.  */
  open_err_str[0] = '\0';
  ld->pcap_h = pcap_open_live(capture_opts->iface,
                   capture_opts->has_snaplen ? capture_opts->snaplen :
                                      WTAP_MAX_PACKET_SIZE,
                   capture_opts->promisc_mode, CAP_READ_TIMEOUT,
                   open_err_str);

  if (ld->pcap_h != NULL) {
    /* we've opened "iface" as a network device */
#ifdef _WIN32
    /* try to set the capture buffer size */
    if (pcap_setbuff(ld->pcap_h, capture_opts->buffer_size * 1024 * 1024) != 0) {
        sync_secondary_msg_str = g_strdup_printf(
          "The capture buffer size of %luMB seems to be too high for your machine,\n"
          "the default of 1MB will be used.\n"
          "\n"
          "Nonetheless, the capture is started.\n",
          capture_opts->buffer_size);
        report_capture_error("Couldn't set the capture buffer size!",
                                   sync_secondary_msg_str);
        g_free(sync_secondary_msg_str);
    }
#endif

    /* setting the data link type only works on real interfaces */
    if (capture_opts->linktype != -1) {
      set_linktype_err_str = set_pcap_linktype(ld->pcap_h, capture_opts->iface,
      capture_opts->linktype);
      if (set_linktype_err_str != NULL) {
      g_snprintf(errmsg, errmsg_len, "Unable to set data link type (%s).",
                 set_linktype_err_str);
        g_snprintf(secondary_errmsg, secondary_errmsg_len, please_report);
      return FALSE;
      }
    }
    ld->linktype = get_pcap_linktype(ld->pcap_h, capture_opts->iface);
  } else {
    /* We couldn't open "iface" as a network device. */
    /* Try to open it as a pipe */
    ld->cap_pipe_fd = cap_pipe_open_live(capture_opts->iface, &ld->cap_pipe_hdr, ld, errmsg, errmsg_len);

    if (ld->cap_pipe_fd == -1) {

      if (ld->cap_pipe_err == PIPNEXIST) {
      /* Pipe doesn't exist, so output message for interface */

      /* If we got a "can't find PPA for X" message, warn the user (who
         is running (T)Wireshark on HP-UX) that they don't have a version
         of libpcap that properly handles HP-UX (libpcap 0.6.x and later
         versions, which properly handle HP-UX, say "can't find /dev/dlpi
         PPA for X" rather than "can't find PPA for X"). */
      if (strncmp(open_err_str, ppamsg, sizeof ppamsg - 1) == 0)
        libpcap_warn =
          "\n\n"
          "You are running (T)Wireshark with a version of the libpcap library\n"
          "that doesn't handle HP-UX network devices well; this means that\n"
          "(T)Wireshark may not be able to capture packets.\n"
          "\n"
          "To fix this, you should install libpcap 0.6.2, or a later version\n"
          "of libpcap, rather than libpcap 0.4 or 0.5.x.  It is available in\n"
          "packaged binary form from the Software Porting And Archive Centre\n"
          "for HP-UX; the Centre is at http://hpux.connect.org.uk/ - the page\n"
          "at the URL lists a number of mirror sites.";
      else
        libpcap_warn = "";
      g_snprintf(errmsg, errmsg_len,
        "The capture session could not be initiated (%s).", open_err_str);
#ifndef _WIN32
      g_snprintf(secondary_errmsg, secondary_errmsg_len,
"Please check to make sure you have sufficient permissions, and that you have\n"
"the proper interface or pipe specified.%s", libpcap_warn);
#else
    g_snprintf(secondary_errmsg, secondary_errmsg_len,
"\n"
"Please check that \"%s\" is the proper interface.\n"
"\n"
"\n"
"Help can be found at:\n"
"\n"
"       http://wiki.wireshark.org/CaptureSetup\n"
"\n"
"64-bit Windows:\n"
"WinPcap does not support 64-bit Windows; you will have to use some other\n"
"tool to capture traffic, such as netcap.\n"
"For netcap details see: http://support.microsoft.com/?id=310875\n"
"\n"
"Modem (PPP/WAN):\n"
"Note that version 3.0 of WinPcap, and earlier versions of WinPcap, don't\n"
"support capturing on PPP/WAN interfaces on Windows NT 4.0 / 2000 / XP /\n"
"Server 2003.\n"
"WinPcap 3.1 has support for it on Windows 2000 / XP / Server 2003, but has no\n"
"support for it on Windows NT 4.0 or Windows Vista (Beta 1).",
    capture_opts->iface);
#endif /* _WIN32 */
      }
      /*
       * Else pipe (or file) does exist and cap_pipe_open_live() has
       * filled in errmsg
       */
      return FALSE;
    } else
      /* cap_pipe_open_live() succeeded; don't want
         error message from pcap_open_live() */
      open_err_str[0] = '\0';
  }

/* XXX - will this work for tshark? */
#ifdef MUST_DO_SELECT
  if (!ld->from_cap_pipe) {
#ifdef HAVE_PCAP_GET_SELECTABLE_FD
    ld->pcap_fd = pcap_get_selectable_fd(ld->pcap_h);
#else
    ld->pcap_fd = pcap_fileno(ld->pcap_h);
#endif
  }
#endif

  /* Does "open_err_str" contain a non-empty string?  If so, "pcap_open_live()"
     returned a warning; print it, but keep capturing. */
  if (open_err_str[0] != '\0') {
    sync_msg_str = g_strdup_printf("%s.", open_err_str);
    report_capture_error(sync_msg_str, "");
    g_free(sync_msg_str);
  }

  return TRUE;
}


/* close the capture input file (pcap or capture pipe) */
static void capture_loop_close_input(loop_data *ld) {

  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_close_input");

  /* if open, close the capture pipe "input file" */
  if (ld->cap_pipe_fd >= 0) {
    g_assert(ld->from_cap_pipe);
    eth_close(ld->cap_pipe_fd);
  }

  /* if open, close the pcap "input file" */
  if(ld->pcap_h != NULL) {
    g_assert(!ld->from_cap_pipe);
    pcap_close(ld->pcap_h);
  }

#ifdef _WIN32
  /* Shut down windows sockets */
  WSACleanup();
#endif
}


/* init the capture filter */
initfilter_status_t capture_loop_init_filter(pcap_t *pcap_h, gboolean from_cap_pipe, const gchar * iface, gchar * cfilter) {
  bpf_u_int32 netnum, netmask;
  gchar       lookup_net_err_str[PCAP_ERRBUF_SIZE];
  struct bpf_program fcode;


  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_init_filter: %s", cfilter);

  /* capture filters only work on real interfaces */
  if (cfilter && !from_cap_pipe) {
    /* A capture filter was specified; set it up. */
    if (pcap_lookupnet(iface, &netnum, &netmask, lookup_net_err_str) < 0) {
      /*
       * Well, we can't get the netmask for this interface; it's used
       * only for filters that check for broadcast IP addresses, so
       * we just punt and use 0.  It might be nice to warn the user,
       * but that's a pain in a GUI application, as it'd involve popping
       * up a message box, and it's not clear how often this would make
       * a difference (only filters that check for IP broadcast addresses
       * use the netmask).
       */
      /*cmdarg_err(
        "Warning:  Couldn't obtain netmask info (%s).", lookup_net_err_str);*/
      netmask = 0;
    }
    if (pcap_compile(pcap_h, &fcode, cfilter, 1, netmask) < 0) {
      /* Treat this specially - our caller might try to compile this
         as a display filter and, if that succeeds, warn the user that
         the display and capture filter syntaxes are different. */
      return INITFILTER_BAD_FILTER;
    }
    if (pcap_setfilter(pcap_h, &fcode) < 0) {
#ifdef HAVE_PCAP_FREECODE
      pcap_freecode(&fcode);
#endif
      return INITFILTER_OTHER_ERROR;
    }
#ifdef HAVE_PCAP_FREECODE
    pcap_freecode(&fcode);
#endif
  }

  return INITFILTER_NO_ERROR;
}


/* set up to write to the already-opened capture output file/files */
gboolean capture_loop_init_output(capture_options *capture_opts, int save_file_fd, loop_data *ld, char *errmsg, int errmsg_len) {
  int         file_snaplen;
  int         err;


  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_init_output");

  /* get snaplen */
  if (ld->from_cap_pipe) {
    file_snaplen = ld->cap_pipe_hdr.snaplen;
  } else
  {
    file_snaplen = pcap_snapshot(ld->pcap_h);
  }

  /* Set up to write to the capture file. */
  if (capture_opts->multi_files_on) {
    ld->pdh = ringbuf_init_libpcap_fdopen(ld->linktype, file_snaplen,
                                          &ld->bytes_written, &err);
  } else {
    ld->pdh = libpcap_fdopen(save_file_fd, ld->linktype, file_snaplen,
                             &ld->bytes_written, &err);
  }

  if (ld->pdh == NULL) {
    /* We couldn't set up to write to the capture file. */
    /* XXX - use cf_open_error_message from tshark instead? */
    switch (err) {

    case WTAP_ERR_CANT_OPEN:
      strcpy(errmsg, "The file to which the capture would be saved"
               " couldn't be created for some unknown reason.");
      break;

    case WTAP_ERR_SHORT_WRITE:
      strcpy(errmsg, "A full header couldn't be written to the file"
               " to which the capture would be saved.");
      break;

    default:
      if (err < 0) {
        g_snprintf(errmsg, errmsg_len,
                 "The file to which the capture would be"
                     " saved (\"%s\") could not be opened: Error %d.",
                  capture_opts->save_file, err);
      } else {
        g_snprintf(errmsg, errmsg_len,
                 "The file to which the capture would be"
                     " saved (\"%s\") could not be opened: %s.",
                  capture_opts->save_file, strerror(err));
      }
      break;
    }

    return FALSE;
  }

  return TRUE;
}

gboolean capture_loop_close_output(capture_options *capture_opts, loop_data *ld, int *err_close) {

  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_close_output");

  if (capture_opts->multi_files_on) {
    return ringbuf_libpcap_dump_close(&capture_opts->save_file, err_close);
  } else {
    return libpcap_dump_close(ld->pdh, err_close);
  }
}

/* dispatch incoming packets (pcap or capture pipe) */
int
capture_loop_dispatch(capture_options *capture_opts _U_, loop_data *ld,
                  char *errmsg, int errmsg_len) {
  int       inpkts;
  int         sel_ret;
  guchar pcap_data[WTAP_MAX_PACKET_SIZE];

  if (ld->from_cap_pipe) {
    /* dispatch from capture pipe */
#ifdef LOG_CAPTURE_VERBOSE
    g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_dispatch: from capture pipe");
#endif
    sel_ret = cap_pipe_select(ld->cap_pipe_fd, FALSE);
    if (sel_ret <= 0) {
      inpkts = 0;
      if (sel_ret < 0 && errno != EINTR) {
        g_snprintf(errmsg, errmsg_len,
          "Unexpected error from select: %s", strerror(errno));
        report_capture_error(errmsg, please_report);
        ld->go = FALSE;
      }
    } else {
      /*
       * "select()" says we can read from the pipe without blocking
       */
      inpkts = cap_pipe_dispatch(ld, pcap_data, errmsg, errmsg_len);
      if (inpkts < 0) {
        ld->go = FALSE;
      }
    }
  }
  else
  {
    /* dispatch from pcap */
#ifdef MUST_DO_SELECT
    /*
     * If we have "pcap_get_selectable_fd()", we use it to get the
     * descriptor on which to select; if that's -1, it means there
     * is no descriptor on which you can do a "select()" (perhaps
     * because you're capturing on a special device, and that device's
     * driver unfortunately doesn't support "select()", in which case
     * we don't do the select - which means it might not be possible
     * to stop a capture until a packet arrives.  If that's unacceptable,
     * plead with whoever supplies the software for that device to add
     * "select()" support, or upgrade to libpcap 0.8.1 or later, and
     * rebuild Wireshark or get a version built with libpcap 0.8.1 or
     * later, so it can use pcap_breakloop().
     */
#ifdef LOG_CAPTURE_VERBOSE
    g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_dispatch: from pcap_dispatch with select");
#endif
    if (ld->pcap_fd != -1) {
      sel_ret = cap_pipe_select(ld->pcap_fd, TRUE);
      if (sel_ret > 0) {
        /*
         * "select()" says we can read from it without blocking; go for
         * it.
         *
         * We don't have pcap_breakloop(), so we only process one packet
         * per pcap_dispatch() call, to allow a signal to stop the
         * processing immediately, rather than processing all packets
         * in a batch before quitting.
         */
        inpkts = pcap_dispatch(ld->pcap_h, 1, ld->packet_cb, (u_char *)ld);
        if (inpkts < 0) {
          ld->pcap_err = TRUE;
          ld->go = FALSE; /* error or pcap_breakloop() - stop capturing */
        }
      } else {
        inpkts = 0;
        if (sel_ret < 0 && errno != EINTR) {
          g_snprintf(errmsg, errmsg_len,
            "Unexpected error from select: %s", strerror(errno));
          report_capture_error(errmsg, please_report);
          ld->go = FALSE;
        }
      }
    }
    else
#endif /* MUST_DO_SELECT */
    {
      /* dispatch from pcap without select */
#if 1
#ifdef LOG_CAPTURE_VERBOSE
      g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_dispatch: from pcap_dispatch");
#endif
#ifdef _WIN32
      /*
       * On Windows, we don't support asynchronously telling a process to
       * stop capturing; instead, we check for an indication on a pipe
       * after processing packets.  We therefore process only one packet
       * at a time, so that we can check the pipe after every packet.
       */
      inpkts = pcap_dispatch(ld->pcap_h, 1, ld->packet_cb, (u_char *) ld);
#else
      inpkts = pcap_dispatch(ld->pcap_h, -1, ld->packet_cb, (u_char *) ld);
#endif
      if (inpkts < 0) {
        if (inpkts == -1) {
          /* Error, rather than pcap_breakloop(). */
          ld->pcap_err = TRUE;
        }
        ld->go = FALSE; /* error or pcap_breakloop() - stop capturing */
      }
#else /* pcap_next_ex */
#ifdef LOG_CAPTURE_VERBOSE
      g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_dispatch: from pcap_next_ex");
#endif
      /* XXX - this is currently unused, as there is some confusion with pcap_next_ex() vs. pcap_dispatch() */

      /*
       * WinPcap's remote capturing feature doesn't work with pcap_dispatch(),
       * see http://wiki.wireshark.org/CaptureSetup_2fWinPcapRemote
       * This should be fixed in the WinPcap 4.0 alpha release.
       *
       * For reference, an example remote interface:
       * rpcap://[1.2.3.4]/\Device\NPF_{39993D68-7C9B-4439-A329-F2D888DA7C5C}
       */

      /* emulate dispatch from pcap */
      {
        int in;
        struct pcap_pkthdr *pkt_header;
        u_char *pkt_data;

        inpkts = 0;
        in = 0;
        while(ld->go &&
              (in = pcap_next_ex(ld->pcap_h, &pkt_header, &pkt_data)) == 1) {
          ld->packet_cb( (u_char *) ld, pkt_header, pkt_data);
          inpkts++;
        }

        if(in < 0) {
          ld->pcap_err = TRUE;
          ld->go = FALSE;
          inpkts = in;
        }
      }
#endif /* pcap_next_ex */
    }
  }

#ifdef LOG_CAPTURE_VERBOSE
  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_dispatch: %d new packet%s", inpkts, plurality(inpkts, "", "s"));
#endif

  return inpkts;
}


/* open the output file (temporary/specified name/ringbuffer/named pipe/stdout) */
/* Returns TRUE if the file opened successfully, FALSE otherwise. */
gboolean
capture_loop_open_output(capture_options *capture_opts, int *save_file_fd,
                  char *errmsg, int errmsg_len) {

  char tmpname[128+1];
  gchar *capfile_name;
  gboolean is_tempfile;


  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_open_output: %s",
      (capture_opts->save_file) ? capture_opts->save_file : "");

  if (capture_opts->save_file != NULL) {
    /* We return to the caller while the capture is in progress.
     * Therefore we need to take a copy of save_file in
     * case the caller destroys it after we return.
     */
    capfile_name = g_strdup(capture_opts->save_file);
    if (strcmp(capfile_name, "-") == 0) {
      /* Write to the standard output. */
      if (capture_opts->multi_files_on) {
        /* ringbuffer is enabled; that doesn't work with standard output */
        g_snprintf(errmsg, errmsg_len,
          "Ring buffer requested, but capture is being written to the standard output.");
        g_free(capfile_name);
        return FALSE;
      } else {
        *save_file_fd = 1;
      }
    } else {
      if (capture_opts->multi_files_on) {
        /* ringbuffer is enabled */
        *save_file_fd = ringbuf_init(capfile_name,
            (capture_opts->has_ring_num_files) ? capture_opts->ring_num_files : 0);

        /* we need the ringbuf name */
        if(*save_file_fd != -1) {
            g_free(capfile_name);
            capfile_name = g_strdup(ringbuf_current_filename());
        }
      } else {
        /* Try to open/create the specified file for use as a capture buffer. */
        *save_file_fd = open(capfile_name, O_RDWR|O_BINARY|O_TRUNC|O_CREAT,
                             0600);
      }
    }
    is_tempfile = FALSE;
  } else {
    /* Choose a random name for the temporary capture buffer */
    *save_file_fd = create_tempfile(tmpname, sizeof tmpname, "ether");
    capfile_name = g_strdup(tmpname);
    is_tempfile = TRUE;
  }

  /* did we fail to open the output file? */
  if (*save_file_fd == -1) {
    if (is_tempfile) {
      g_snprintf(errmsg, errmsg_len,
      "The temporary file to which the capture would be saved (\"%s\") "
      "could not be opened: %s.", capfile_name, strerror(errno));
    } else {
      if (capture_opts->multi_files_on) {
        ringbuf_error_cleanup();
      }

      g_snprintf(errmsg, errmsg_len,
          "The file to which the capture would be saved (\"%s\") "
        "could not be opened: %s.", capfile_name,
        strerror(errno));
    }
    g_free(capfile_name);
    return FALSE;
  }

  if(capture_opts->save_file != NULL) {
    g_free(capture_opts->save_file);
  }
  capture_opts->save_file = capfile_name;
  /* capture_opts.save_file is "g_free"ed later, which is equivalent to
     "g_free(capfile_name)". */

  return TRUE;
}


static void
capture_loop_stop_signal_handler(int signo _U_)
{
  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_INFO, "Signal: Stop capture");
  capture_loop_stop();
}

#ifdef _WIN32
#define TIME_GET() GetTickCount()
#else
#define TIME_GET() time(NULL)
#endif

/* Do the low-level work of a capture.
   Returns TRUE if it succeeds, FALSE otherwise. */
int
capture_loop_start(capture_options *capture_opts, gboolean *stats_known, struct pcap_stat *stats)
{
#ifndef _WIN32
  struct sigaction act;
#endif
  time_t      upd_time, cur_time;
  time_t      start_time;
  int         err_close;
  int         inpkts;
  gint        inpkts_to_sync_pipe = 0;     /* packets not already send out to the sync_pipe */
  condition  *cnd_file_duration = NULL;
  condition  *cnd_autostop_files = NULL;
  condition  *cnd_autostop_size = NULL;
  condition  *cnd_autostop_duration = NULL;
  guint32     autostop_files = 0;
  gboolean    write_ok;
  gboolean    close_ok;
  gboolean    cfilter_error = FALSE;
  char        errmsg[4096+1];
  char        secondary_errmsg[4096+1];
  int         save_file_fd = -1;


  /* init the loop data */
  ld.go                 = TRUE;
  ld.packet_count       = 0;
  if (capture_opts->has_autostop_packets)
    ld.packet_max       = capture_opts->autostop_packets;
  else
    ld.packet_max       = 0;  /* no limit */
  ld.err                = 0;  /* no error seen yet */
  ld.wtap_linktype      = WTAP_ENCAP_UNKNOWN;
  ld.pcap_err           = FALSE;
  ld.from_cap_pipe      = FALSE;
  ld.pdh                = NULL;
  ld.cap_pipe_fd        = -1;
#ifdef MUST_DO_SELECT
  ld.pcap_fd            = 0;
#endif
  ld.packet_cb          = capture_loop_packet_cb;


  /* We haven't yet gotten the capture statistics. */
  *stats_known      = FALSE;

#ifndef _WIN32
  /*
   * Catch SIGUSR1, so that we exit cleanly if the parent process
   * kills us with it due to the user selecting "Capture->Stop".
   */
  act.sa_handler = capture_loop_stop_signal_handler;
  /*
   * Arrange that system calls not get restarted, because when
   * our signal handler returns we don't want to restart
   * a call that was waiting for packets to arrive.
   */
  act.sa_flags = 0;
  sigemptyset(&act.sa_mask);
  sigaction(SIGUSR1, &act, NULL);
#endif /* _WIN32 */

  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_INFO, "Capture loop starting ...");
  capture_opts_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, capture_opts);

  /* open the "input file" from network interface or capture pipe */
  if (!capture_loop_open_input(capture_opts, &ld, errmsg, sizeof(errmsg),
                               secondary_errmsg, sizeof(secondary_errmsg))) {
    goto error;
  }

  /* init the input filter from the network interface (capture pipe will do nothing) */
  switch (capture_loop_init_filter(ld.pcap_h, ld.from_cap_pipe, capture_opts->iface, capture_opts->cfilter)) {

  case INITFILTER_NO_ERROR:
    break;

  case INITFILTER_BAD_FILTER:
    cfilter_error = TRUE;
    g_snprintf(errmsg, sizeof(errmsg), "%s", pcap_geterr(ld.pcap_h));
    *secondary_errmsg = '\0';
    goto error;

  case INITFILTER_OTHER_ERROR:
    g_snprintf(errmsg, sizeof(errmsg), "Can't install filter (%s).",
               pcap_geterr(ld.pcap_h));
    g_snprintf(secondary_errmsg, sizeof(secondary_errmsg), "%s", please_report);
    goto error;
  }

  /* If we're supposed to write to a capture file, open it for output
     (temporary/specified name/ringbuffer) */
  if (capture_opts->saving_to_file) {
    if (!capture_loop_open_output(capture_opts, &save_file_fd, errmsg, sizeof(errmsg))) {
      *secondary_errmsg = '\0';
      goto error;
    }

    /* set up to write to the already-opened capture output file/files */
    if (!capture_loop_init_output(capture_opts, save_file_fd, &ld, errmsg, sizeof(errmsg))) {
      *secondary_errmsg = '\0';
      goto error;
    }

  /* XXX - capture SIGTERM and close the capture, in case we're on a
     Linux 2.0[.x] system and you have to explicitly close the capture
     stream in order to turn promiscuous mode off?  We need to do that
     in other places as well - and I don't think that works all the
     time in any case, due to libpcap bugs. */

    /* Well, we should be able to start capturing.

       Sync out the capture file, so the header makes it to the file system,
       and send a "capture started successfully and capture file created"
       message to our parent so that they'll open the capture file and
       update its windows to indicate that we have a live capture in
       progress. */
    libpcap_dump_flush(ld.pdh, NULL);
    report_new_capture_file(capture_opts->save_file);
  }

  /* initialize capture stop (and alike) conditions */
  init_capture_stop_conditions();
  /* create stop conditions */
  if (capture_opts->has_autostop_filesize)
    cnd_autostop_size =
        cnd_new(CND_CLASS_CAPTURESIZE,(long)capture_opts->autostop_filesize * 1024);
  if (capture_opts->has_autostop_duration)
    cnd_autostop_duration =
        cnd_new(CND_CLASS_TIMEOUT,(gint32)capture_opts->autostop_duration);

  if (capture_opts->multi_files_on) {
      if (capture_opts->has_file_duration)
        cnd_file_duration =
          cnd_new(CND_CLASS_TIMEOUT, capture_opts->file_duration);

      if (capture_opts->has_autostop_files)
        cnd_autostop_files =
          cnd_new(CND_CLASS_CAPTURESIZE, capture_opts->autostop_files);
  }

  /* init the time values */
  start_time = TIME_GET();
  upd_time = TIME_GET();

  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_INFO, "Capture loop running!");

  /* WOW, everything is prepared! */
  /* please fasten your seat belts, we will enter now the actual capture loop */
  while (ld.go) {
    /* dispatch incoming packets */
    inpkts = capture_loop_dispatch(capture_opts, &ld, errmsg, sizeof(errmsg));

#ifdef _WIN32
    /* any news from our parent (signal pipe)? -> just stop the capture */
    if (!signal_pipe_check_running()) {
      ld.go = FALSE;
    }
#endif

    if (inpkts > 0) {
      inpkts_to_sync_pipe += inpkts;

      /* check capture size condition */
      if (cnd_autostop_size != NULL &&
          cnd_eval(cnd_autostop_size, (guint32)ld.bytes_written)){
        /* Capture size limit reached, do we have another file? */
        if (capture_opts->multi_files_on) {
          if (cnd_autostop_files != NULL &&
              cnd_eval(cnd_autostop_files, ++autostop_files)) {
             /* no files left: stop here */
            ld.go = FALSE;
            continue;
          }

          /* Switch to the next ringbuffer file */
          if (ringbuf_switch_file(&ld.pdh, &capture_opts->save_file,
              &save_file_fd, &ld.bytes_written, &ld.err)) {
            /* File switch succeeded: reset the conditions */
            cnd_reset(cnd_autostop_size);
            if (cnd_file_duration) {
              cnd_reset(cnd_file_duration);
            }
            libpcap_dump_flush(ld.pdh, NULL);
            report_packet_count(inpkts_to_sync_pipe);
            inpkts_to_sync_pipe = 0;
            report_new_capture_file(capture_opts->save_file);
          } else {
            /* File switch failed: stop here */
            ld.go = FALSE;
            continue;
          }
        } else {
          /* single file, stop now */
          ld.go = FALSE;
          continue;
        }
      } /* cnd_autostop_size */
      if (capture_opts->output_to_pipe) {
        libpcap_dump_flush(ld.pdh, NULL);
      }
    } /* inpkts */

    /* Only update once a second (Win32: 500ms) so as not to overload slow displays */
    cur_time = TIME_GET();
#ifdef _WIN32
    if ( (cur_time - upd_time) > 500) {
#else
    if (cur_time - upd_time > 0) {
#endif
        upd_time = cur_time;

      /*if (pcap_stats(pch, stats) >= 0) {
        *stats_known = TRUE;
      }*/

      /* Let the parent process know. */
      if (inpkts_to_sync_pipe) {
        /* do sync here */
        libpcap_dump_flush(ld.pdh, NULL);

        /* Send our parent a message saying we've written out "inpkts_to_sync_pipe"
           packets to the capture file. */
        report_packet_count(inpkts_to_sync_pipe);

        inpkts_to_sync_pipe = 0;
      }

      /* check capture duration condition */
      if (cnd_autostop_duration != NULL && cnd_eval(cnd_autostop_duration)) {
        /* The maximum capture time has elapsed; stop the capture. */
        ld.go = FALSE;
        continue;
      }

      /* check capture file duration condition */
      if (cnd_file_duration != NULL && cnd_eval(cnd_file_duration)) {
        /* duration limit reached, do we have another file? */
        if (capture_opts->multi_files_on) {
          if (cnd_autostop_files != NULL &&
              cnd_eval(cnd_autostop_files, ++autostop_files)) {
            /* no files left: stop here */
            ld.go = FALSE;
            continue;
          }

          /* Switch to the next ringbuffer file */
          if (ringbuf_switch_file(&ld.pdh, &capture_opts->save_file,
                                  &save_file_fd, &ld.bytes_written, &ld.err)) {
            /* file switch succeeded: reset the conditions */
            cnd_reset(cnd_file_duration);
            if(cnd_autostop_size)
              cnd_reset(cnd_autostop_size);
            libpcap_dump_flush(ld.pdh, NULL);
            report_packet_count(inpkts_to_sync_pipe);
            inpkts_to_sync_pipe = 0;
            report_new_capture_file(capture_opts->save_file);
          } else {
            /* File switch failed: stop here */
            ld.go = FALSE;
            continue;
          }
        } else {
          /* single file, stop now */
          ld.go = FALSE;
          continue;
        }
      } /* cnd_file_duration */
    }

  } /* while (ld.go) */

  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_INFO, "Capture loop stopping ...");

  /* delete stop conditions */
  if (cnd_file_duration != NULL)
    cnd_delete(cnd_file_duration);
  if (cnd_autostop_files != NULL)
    cnd_delete(cnd_autostop_files);
  if (cnd_autostop_size != NULL)
    cnd_delete(cnd_autostop_size);
  if (cnd_autostop_duration != NULL)
    cnd_delete(cnd_autostop_duration);

  /* did we had a pcap (input) error? */
  if (ld.pcap_err) {
    g_snprintf(errmsg, sizeof(errmsg), "Error while capturing packets: %s",
      pcap_geterr(ld.pcap_h));
    report_capture_error(errmsg, please_report);
  }
    else if (ld.from_cap_pipe && ld.cap_pipe_err == PIPERR)
      report_capture_error(errmsg, "");

  /* did we had an error while capturing? */
  if (ld.err == 0) {
    write_ok = TRUE;
  } else {
    capture_loop_get_errmsg(errmsg, sizeof(errmsg), capture_opts->save_file, ld.err,
                        FALSE);
    report_capture_error(errmsg, please_report);
    write_ok = FALSE;
  }

  if (capture_opts->saving_to_file) {
    /* close the wiretap (output) file */
    close_ok = capture_loop_close_output(capture_opts, &ld, &err_close);
  } else
    close_ok = TRUE;

  /* there might be packets not yet notified to the parent */
  /* (do this after closing the file, so all packets are already flushed) */
  if(inpkts_to_sync_pipe) {
    report_packet_count(inpkts_to_sync_pipe);
    inpkts_to_sync_pipe = 0;
  }

  /* If we've displayed a message about a write error, there's no point
     in displaying another message about an error on close. */
  if (!close_ok && write_ok) {
    capture_loop_get_errmsg(errmsg, sizeof(errmsg), capture_opts->save_file, err_close,
            TRUE);
    report_capture_error(errmsg, "");
  }

  /*
   * XXX We exhibit different behaviour between normal mode and sync mode
   * when the pipe is stdin and not already at EOF.  If we're a child, the
   * parent's stdin isn't closed, so if the user starts another capture,
   * cap_pipe_open_live() will very likely not see the expected magic bytes and
   * will say "Unrecognized libpcap format".  On the other hand, in normal
   * mode, cap_pipe_open_live() will say "End of file on pipe during open".
   */

  /* get packet drop statistics from pcap */
  if(ld.pcap_h != NULL) {
    g_assert(!ld.from_cap_pipe);
    /* Get the capture statistics, so we know how many packets were
       dropped. */
    if (pcap_stats(ld.pcap_h, stats) >= 0) {
      *stats_known = TRUE;
      /* Let the parent process know. */
      report_packet_drops(stats->ps_drop);
    } else {
      g_snprintf(errmsg, sizeof(errmsg),
            "Can't get packet-drop statistics: %s",
            pcap_geterr(ld.pcap_h));
      report_capture_error(errmsg, please_report);
    }
  }

  /* close the input file (pcap or capture pipe) */
  capture_loop_close_input(&ld);

  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_INFO, "Capture loop stopped!");

  /* ok, if the write and the close were successful. */
  return write_ok && close_ok;

error:
  if (capture_opts->multi_files_on) {
    /* cleanup ringbuffer */
    ringbuf_error_cleanup();
  } else {
    /* We can't use the save file, and we have no FILE * for the stream
       to close in order to close it, so close the FD directly. */
    if(save_file_fd != -1) {
      eth_close(save_file_fd);
    }

    /* We couldn't even start the capture, so get rid of the capture
       file. */
    if(capture_opts->save_file != NULL) {
      eth_unlink(capture_opts->save_file);
      g_free(capture_opts->save_file);
    }
  }
  capture_opts->save_file = NULL;
  if (cfilter_error)
    report_cfilter_error(capture_opts->cfilter, errmsg);
  else
    report_capture_error(errmsg, secondary_errmsg);

  /* close the input file (pcap or cap_pipe) */
  capture_loop_close_input(&ld);

  g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_INFO, "Capture loop stopped with error");

  return FALSE;
}


void capture_loop_stop(void)
{
#ifdef HAVE_PCAP_BREAKLOOP
  if(ld.pcap_h != NULL)
    pcap_breakloop(ld.pcap_h);
#endif
  ld.go = FALSE;
}


static void
capture_loop_get_errmsg(char *errmsg, int errmsglen, const char *fname,
                    int err, gboolean is_close)
{
  switch (err) {

  case ENOSPC:
    g_snprintf(errmsg, errmsglen,
            "Not all the packets could be written to the file"
            " to which the capture was being saved\n"
            "(\"%s\") because there is no space left on the file system\n"
            "on which that file resides.",
            fname);
    break;

#ifdef EDQUOT
  case EDQUOT:
    g_snprintf(errmsg, errmsglen,
            "Not all the packets could be written to the file"
            " to which the capture was being saved\n"
            "(\"%s\") because you are too close to, or over,"
            " your disk quota\n"
            "on the file system on which that file resides.",
            fname);
  break;
#endif

  case WTAP_ERR_CANT_CLOSE:
    g_snprintf(errmsg, errmsglen,
            "The file to which the capture was being saved"
            " couldn't be closed for some unknown reason.");
    break;

  case WTAP_ERR_SHORT_WRITE:
    g_snprintf(errmsg, errmsglen,
            "Not all the packets could be written to the file"
            " to which the capture was being saved\n"
            "(\"%s\").",
            fname);
    break;

  default:
    if (is_close) {
      g_snprintf(errmsg, errmsglen,
            "The file to which the capture was being saved\n"
            "(\"%s\") could not be closed: %s.",
            fname, wtap_strerror(err));
    } else {
      g_snprintf(errmsg, errmsglen,
            "An error occurred while writing to the file"
            " to which the capture was being saved\n"
            "(\"%s\"): %s.",
            fname, wtap_strerror(err));
    }
    break;
  }
}


/* one packet was captured, process it */
static void
capture_loop_packet_cb(u_char *user, const struct pcap_pkthdr *phdr,
  const u_char *pd)
{
  loop_data *ld = (loop_data *) user;
  int err;

  /* if the user told us to stop after x packets, do we have enough? */
  ld->packet_count++;
  if ((ld->packet_max > 0) && (ld->packet_count >= ld->packet_max))
  {
     ld->go = FALSE;
  }

  if (ld->pdh) {
    /* We're supposed to write the packet to a file; do so.
       If this fails, set "ld->go" to FALSE, to stop the capture, and set
       "ld->err" to the error. */
    if (!libpcap_write_packet(ld->pdh, phdr, pd, &ld->bytes_written, &err)) {
      ld->go = FALSE;
      ld->err = err;
    }
  }
}

#endif /* HAVE_LIBPCAP */

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