Pull capture_loop.c into dumpcap.c, as dumpcap is the only program that

does capturing any more.  (We will be inserting a call to give up
privileges after the pcap_open_live(), which should fix 2273; we're
currently only giving up privileges on platforms with libcap.)

svn path=/trunk/; revision=24345

1 files changed, 1844 insertions, 14 deletions

diff --git a/dumpcap.c b/dumpcap.c
index c44bfe6167..3f048d845b 100644
--- a/dumpcap.c
+++ b/dumpcap.c
@@ -31,11 +31,24 @@
 #include <string.h>
 #include <ctype.h>
 
+#ifdef HAVE_SYS_TYPES_H
+# include <sys/types.h>
+#endif
+
+#ifdef HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
 
 #include <signal.h>
+#include <errno.h>
 
 #ifdef NEED_GETOPT_H
 #include "getopt.h"
@@ -57,6 +70,8 @@
 #include "version_info.h"
 
 #include <pcap.h>
+#include "pcapio.h"
+
 #include "capture-pcap-util.h"
 
 #ifdef _WIN32
@@ -74,37 +89,189 @@
 #include "sync_pipe.h"
 
 #include "capture.h"
-#include "capture_loop.h"
 #include "capture_sync.h"
 
-#include "simple_dialog.h"
-#include "util.h"
+#include "conditions.h"
+#include "capture_stop_conditions.h"
+
+#include "tempfile.h"
 #include "log.h"
 #include "file_util.h"
 
+#include "epan/unicode-utils.h"
+
+#ifdef NEED_G_ASCII_STRCASECMP_H
+#include "epan/g_ascii_strcasecmp.h"
+#endif
+
+/*
+ * Get information about libpcap format from "wiretap/libpcap.h".
+ * XXX - can we just use pcap_open_offline() to read the pipe?
+ */
+#include "wiretap/libpcap.h"
 
 /*#define DEBUG_DUMPCAP*/
 
-gboolean capture_child = FALSE; /* FALSE: standalone call, TRUE: this is an Wireshark capture child */
+static gboolean capture_child = FALSE; /* FALSE: standalone call, TRUE: this is an Wireshark capture child */
 #ifdef _WIN32
-gchar *sig_pipe_name = NULL;
-HANDLE sig_pipe_handle = NULL;
+static gchar *sig_pipe_name = NULL;
+static HANDLE sig_pipe_handle = NULL;
+#endif
+
+/** Stop a low-level capture (stops the capture child). */
+static void capture_loop_stop(void);
+
+#if !defined (__linux__)
+#ifndef HAVE_PCAP_BREAKLOOP
+/*
+ * We don't have pcap_breakloop(), which is the only way to ensure that
+ * pcap_dispatch(), pcap_loop(), or even pcap_next() or pcap_next_ex()
+ * won't, if the call to read the next packet or batch of packets is
+ * is interrupted by a signal on UN*X, just go back and try again to
+ * read again.
+ *
+ * On UN*X, we catch SIGUSR1 as a "stop capturing" signal, and, in
+ * the signal handler, set a flag to stop capturing; however, without
+ * a guarantee of that sort, we can't guarantee that we'll stop capturing
+ * if the read will be retried and won't time out if no packets arrive.
+ *
+ * Therefore, on at least some platforms, we work around the lack of
+ * pcap_breakloop() by doing a select() on the pcap_t's file descriptor
+ * to wait for packets to arrive, so that we're probably going to be
+ * blocked in the select() when the signal arrives, and can just bail
+ * out of the loop at that point.
+ *
+ * However, we don't want to that on BSD (because "select()" doesn't work
+ * correctly on BPF devices on at least some releases of some flavors of
+ * BSD), and we don't want to do it on Windows (because "select()" is
+ * something for sockets, not for arbitrary handles).  (Note that "Windows"
+ * here includes Cygwin; even in its pretend-it's-UNIX environment, we're
+ * using WinPcap, not a UNIX libpcap.)
+ *
+ * Fortunately, we don't need to do it on BSD, because the libpcap timeout
+ * on BSD times out even if no packets have arrived, so we'll eventually
+ * exit pcap_dispatch() with an indication that no packets have arrived,
+ * and will break out of the capture loop at that point.
+ *
+ * On Windows, we can't send a SIGUSR1 to stop capturing, so none of this
+ * applies in any case.
+ *
+ * XXX - the various BSDs appear to define BSD in <sys/param.h>; we don't
+ * want to include it if it's not present on this platform, however.
+ */
+# if !defined(__FreeBSD__) && !defined(__NetBSD__) && !defined(__OpenBSD__) && \
+    !defined(__bsdi__) && !defined(__APPLE__) && !defined(_WIN32) && \
+    !defined(__CYGWIN__)
+#  define MUST_DO_SELECT
+# endif /* avoid select */
+#endif /* HAVE_PCAP_BREAKLOOP */
+#else /* linux */
+/* whatever the deal with pcap_breakloop, linux doesn't support timeouts
+ * in pcap_dispatch(); on the other hand, select() works just fine there.
+ * Hence we use a select for that come what may.
+ */
+#define MUST_DO_SELECT
+#endif
+
+typedef void (*capture_packet_cb_fct)(u_char *, const struct pcap_pkthdr *, const u_char *);
+
+/** init the capture filter */
+typedef enum {
+  INITFILTER_NO_ERROR,
+  INITFILTER_BAD_FILTER,
+  INITFILTER_OTHER_ERROR
+} initfilter_status_t;
+
+typedef struct _loop_data {
+  /* common */
+  gboolean       go;                    /* TRUE as long as we're supposed to keep capturing */
+  int            err;                   /* if non-zero, error seen while capturing */
+  gint           packet_count;          /* Number of packets we have already captured */
+  gint           packet_max;            /* Number of packets we're supposed to capture - 0 means infinite */
+
+  capture_packet_cb_fct  packet_cb;     /* callback for a single captured packet */
+
+  /* pcap "input file" */
+  pcap_t        *pcap_h;                /* pcap handle */
+  gboolean       pcap_err;              /* TRUE if error from pcap */
+#ifdef MUST_DO_SELECT
+  int            pcap_fd;               /* pcap file descriptor */
 #endif
 
+  /* capture pipe (unix only "input file") */
+  gboolean       from_cap_pipe;         /* TRUE if we are capturing data from a capture pipe */
+  struct pcap_hdr cap_pipe_hdr;         /* Pcap header when capturing from a pipe */
+  struct pcaprec_modified_hdr cap_pipe_rechdr;  /* Pcap record header when capturing from a pipe */
+  int            cap_pipe_fd;           /* the file descriptor of the capture pipe */
+  gboolean       cap_pipe_modified;     /* TRUE if data in the pipe uses modified pcap headers */
+  gboolean       cap_pipe_byte_swapped; /* TRUE if data in the pipe is byte swapped */
+  unsigned int   cap_pipe_bytes_to_read;/* Used by cap_pipe_dispatch */
+  unsigned int   cap_pipe_bytes_read;   /* Used by cap_pipe_dispatch */
+  enum {
+         STATE_EXPECT_REC_HDR,
+         STATE_READ_REC_HDR,
+         STATE_EXPECT_DATA,
+         STATE_READ_DATA
+       } cap_pipe_state;
+  enum { PIPOK, PIPEOF, PIPERR, PIPNEXIST } cap_pipe_err;
+
+  /* output file */
+  FILE          *pdh;
+  int            linktype;
+  gint           wtap_linktype;
+  long           bytes_written;
+
+} loop_data;
+
+/*
+ * Standard secondary message for unexpected errors.
+ */
+static const char please_report[] =
+    "Please report this to the Wireshark developers.\n"
+    "(This is not a crash; 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
 console_log_handler(const char *log_domain, GLogLevelFlags log_level,
 		    const char *message, gpointer user_data _U_);
 
 /* capture related options */
-capture_options global_capture_opts;
-capture_options *capture_opts = &global_capture_opts;
+static capture_options global_capture_opts;
+static capture_options *capture_opts = &global_capture_opts;
+
+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);
+
 
 #if __GNUC__ >= 2
-void exit_main(int err) __attribute__ ((noreturn));
+static void exit_main(int err) __attribute__ ((noreturn));
 #else
-void exit_main(int err);
+static void exit_main(int err);
 #endif
 
+static void report_new_capture_file(const char *filename);
+static void report_packet_count(int packet_count);
+static void report_packet_drops(int drops);
+static void report_capture_error(const char *error_msg, const char *secondary_error_msg);
+static void report_cfilter_error(const char *cfilter, const char *errmsg);
+
+#ifdef _WIN32
+static gboolean signal_pipe_check_running(void);
+#endif
 
 static void
 print_usage(gboolean print_ver) {
@@ -275,7 +442,7 @@ capture_cleanup(int signum)
 }
 #endif
 
-void exit_main(int status)
+static void exit_main(int status)
 {
 #ifdef _WIN32
   /* Shutdown windows sockets */
@@ -298,7 +465,7 @@ void exit_main(int status)
  * CAP_NET_ADMIN and CAP_NET_RAW, then relinquish our permissions.
  */
 
-void
+static void
 #if 0 /* Set to enable capability debugging */
 print_caps(char *pfx) {
     cap_t caps = cap_get_proc();
@@ -310,7 +477,7 @@ print_caps(char *pfx _U_) {
 #endif
 }
 
-void
+static void
 relinquish_privs_except_capture(void)
 {
     /* CAP_NET_ADMIN: Promiscuous mode and a truckload of other
@@ -348,6 +515,1669 @@ relinquish_privs_except_capture(void)
 }
 #endif /* HAVE_LIBCAP */
 
+/* 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) {
+#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);
+
+  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 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, CAP_READ_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 1
+  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 */
+#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 ( (pos=strstr(pncopy, "\\\\")) == pncopy) {
+      pos = strchr(pncopy + 3, '\\');
+      if (pos && g_ascii_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 named 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;
+    }
+#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);
+    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);
+    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).
+ *  Returns TRUE if it succeeds, FALSE otherwise. */
+static 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
+#ifdef HAVE_PCAP_REMOTE
+  struct pcap_rmtauth auth;
+#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';
+#ifdef HAVE_PCAP_OPEN
+  auth.type = capture_opts->auth_type == CAPTURE_AUTH_PWD ?
+                    RPCAP_RMTAUTH_PWD : RPCAP_RMTAUTH_NULL;
+  auth.username = capture_opts->auth_username;
+  auth.password = capture_opts->auth_password;
+
+  ld->pcap_h = pcap_open(capture_opts->iface,
+               capture_opts->has_snaplen ? capture_opts->snaplen :
+                          WTAP_MAX_PACKET_SIZE,
+               /* flags */
+               (capture_opts->promisc_mode ? PCAP_OPENFLAG_PROMISCUOUS : 0) |
+               (capture_opts->datatx_udp ? PCAP_OPENFLAG_DATATX_UDP : 0) |
+               (capture_opts->nocap_rpcap ? PCAP_OPENFLAG_NOCAPTURE_RPCAP : 0),
+               CAP_READ_TIMEOUT, &auth, open_err_str);
+#else
+  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);
+#endif
+
+  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
+
+#if defined(HAVE_PCAP_REMOTE) && defined(HAVE_PCAP_SETSAMPLING)
+    if (capture_opts->sampling_method != CAPTURE_SAMP_NONE)
+    {
+        struct pcap_samp *samp;
+
+        if ((samp = pcap_setsampling(ld->pcap_h)) != NULL)
+        {
+            switch (capture_opts->sampling_method)
+            {
+                case CAPTURE_SAMP_BY_COUNT:
+                    samp->method = PCAP_SAMP_1_EVERY_N;
+                    break;
+
+                case CAPTURE_SAMP_BY_TIMER:
+                    samp->method = PCAP_SAMP_FIRST_AFTER_N_MS;
+                    break;
+
+                default:
+                    sync_msg_str = g_strdup_printf(
+                            "Unknown sampling method %d specified,\n"
+                            "continue without packet sampling",
+                            capture_opts->sampling_method);
+                    report_capture_error("Couldn't set the capture "
+                            "sampling", sync_msg_str);
+                    g_free(sync_msg_str);
+            }
+            samp->value = capture_opts->sampling_param;
+        }
+        else
+        {
+            report_capture_error("Couldn't set the capture sampling",
+                    "Cannot get packet sampling data structure");
+        }
+
+    }
+#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 "
+"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);
+    ld->cap_pipe_fd = 0;
+  }
+
+  /* if open, close the pcap "input file" */
+  if(ld->pcap_h != NULL) {
+    g_log(LOG_DOMAIN_CAPTURE_CHILD, G_LOG_LEVEL_DEBUG, "capture_loop_close_input: closing %p", ld->pcap_h);
+    g_assert(!ld->from_cap_pipe);
+    pcap_close(ld->pcap_h);
+    ld->pcap_h = NULL;
+  }
+
+  ld->go = FALSE;
+
+#ifdef _WIN32
+  /* Shut down windows sockets */
+  WSACleanup();
+#endif
+}
+
+
+/* init the capture filter */
+static initfilter_status_t
+capture_loop_init_filter(pcap_t *pcap_h, gboolean from_cap_pipe, 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 */
+static 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:
+      g_snprintf(errmsg, errmsg_len, "The file to which the capture would be saved"
+               " couldn't be created for some unknown reason.");
+      break;
+
+    case WTAP_ERR_SHORT_WRITE:
+      g_snprintf(errmsg, errmsg_len, "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;
+}
+
+static 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)
+ *
+ * Waits for incoming packets to be available, and calls pcap_dispatch()
+ * to cause them to be processed.
+ *
+ * Returns the number of packets which were processed.
+ *
+ * Times out (returning zero) after CAP_READ_TIMEOUT ms; this ensures that the
+ * packet-batching behaviour does not cause packets to get held back
+ * indefinitely.
+ */
+static int
+capture_loop_dispatch(capture_options *capture_opts _U_, loop_data *ld,
+		      char *errmsg, int errmsg_len)
+{
+  int       inpkts;
+  int       sel_ret;
+  gint      packet_count_before;
+  guchar    pcap_data[WTAP_MAX_PACKET_SIZE];
+
+  packet_count_before = ld->packet_count;
+  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);
+    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);
+      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 {
+        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;
+
+        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);
+
+        if(in < 0) {
+          ld->pcap_err = TRUE;
+          ld->go = FALSE;
+        }
+      }
+#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 ld->packet_count - packet_count_before;
+}
+
+
+/* open the output file (temporary/specified name/ringbuffer/named pipe/stdout) */
+/* Returns TRUE if the file opened successfully, FALSE otherwise. */
+static 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 (capture_opts->output_to_pipe == TRUE) { /* either "-" or named pipe */
+      if (capture_opts->multi_files_on) {
+        /* ringbuffer is enabled; that doesn't work with standard output or a named pipe */
+        g_snprintf(errmsg, errmsg_len,
+	    "Ring buffer requested, but capture is being written to standard output or to a named pipe.");
+        g_free(capfile_name);
+        return FALSE;
+      }
+      if (strcmp(capfile_name, "-") == 0) {
+        /* write to stdout */
+        *save_file_fd = 1;
+#ifdef _WIN32
+        /* set output pipe to binary mode to avoid Windows text-mode processing (eg: for CR/LF)  */
+        _setmode(1, O_BINARY);
+#endif
+      }
+    } /* if (...output_to_pipe ... */
+
+    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 = eth_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)". */
+#ifndef _WIN32
+  fchown(*save_file_fd, capture_opts->owner, capture_opts->group);
+#endif
+
+  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. */
+static gboolean
+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;
+#define MSG_MAX_LENGTH 4096
+  char        errmsg[MSG_MAX_LENGTH+1];
+  char        secondary_errmsg[MSG_MAX_LENGTH+1];
+  int         save_file_fd = -1;
+
+  *errmsg           = '\0';
+  *secondary_errmsg = '\0';
+
+  /* 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));
+    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))) {
+      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))) {
+      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. This also prevents too much context-switching between the
+     * dumpcap and wireshark processes */
+    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) {
+    /* On Linux, if an interface goes down while you're capturing on it,
+       you'll get a "recvfrom: Network is down" error (ENETDOWN).
+       (At least you will if strerror() doesn't show a local translation
+       of the error.)
+
+       On FreeBSD and OS X, if a network adapter disappears while
+       you're capturing on it, you'll get a "read: Device not configured"
+       error (ENXIO).  (See previous parenthetical note.)
+
+       On OpenBSD, you get "read: I/O error" (EIO) in the same case.
+
+       These should *not* be reported to the Wireshark developers. */
+    char *cap_err_str;
+
+    cap_err_str = pcap_geterr(ld.pcap_h);
+    if (strcmp(cap_err_str, "recvfrom: Network is down") == 0 ||
+        strcmp(cap_err_str, "read: Device not configured") == 0 ||
+        strcmp(cap_err_str, "read: I/O error") == 0) {
+      report_capture_error("The network adapter on which the capture was being done "
+                           "is no longer running; the capture has stopped.",
+                           "");
+    } else {
+      g_snprintf(errmsg, sizeof(errmsg), "Error while capturing packets: %s",
+        cap_err_str);
+      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;
+}
+
+
+static 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 = (void *) user;
+  int err;
+
+  /* if the user told us to stop after x packets, do we already have enough? */
+  if ((ld->packet_max > 0) && (ld->packet_count >= ld->packet_max))
+  {
+     ld->go = FALSE;
+     return;
+  }
+
+  /* We may be called multiple times from pcap_dispatch(); if we've set
+     the "stop capturing" flag, ignore this packet, as we're not
+     supposed to be saving any more packets. */
+  if (!ld->go)
+    return;
+
+  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;
+    } else
+      ld->packet_count++;
+  }
+}
+
 
 /* And now our feature presentation... [ fade to music ] */
 int
@@ -794,7 +2624,7 @@ report_packet_drops(int drops)
 
 
 #ifdef _WIN32
-gboolean
+static gboolean
 signal_pipe_check_running(void)
 {
     /* any news from our parent? -> just stop the capture */