Allow bigger snapshot lengths for D-Bus captures.

Use WTAP_MAX_PACKET_SIZE_STANDARD, set to 256KB, for everything except
for D-Bus captures.  Use WTAP_MAX_PACKET_SIZE_DBUS, set to 128MB, for
them, because that's the largest possible D-Bus message size.  See

	https://bugs.freedesktop.org/show_bug.cgi?id=100220

for an example of the problems caused by limiting the snapshot length to
256KB for D-Bus.

Have a snapshot length of 0 in a capture_file structure mean "there is
no snapshot length for the file"; we don't need the has_snap field in
that case, a value of 0 mean "no, we don't have a snapshot length".

In dumpcap, start out with a pipe buffer size of 2KB, and grow it as
necessary.  When checking for a too-big packet from a pipe, check
against the appropriate maximum - 128MB for DLT_DBUS, 256KB for
everything else.

Change-Id: Ib2ce7a0cf37b971fbc0318024fd011e18add8b20
Reviewed-on: https://code.wireshark.org/review/21952
Petri-Dish: Guy Harris <guy@alum.mit.edu>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Guy Harris <guy@alum.mit.edu>
(cherry picked from commit d0865fd619454a9ac06b1c7d287dc438aff50bb0)
Reviewed-on: https://code.wireshark.org/review/21955

1 files changed, 0 insertions, 12 deletions

diff --git a/file.c b/file.c
index c30839e9bc..7cbab798ee 100644
--- a/file.c
+++ b/file.c
@@ -342,12 +342,6 @@ cf_open(capture_file *cf, const char *fname, unsigned int type, gboolean is_temp
   cf->drops_known = FALSE;
   cf->drops     = 0;
   cf->snap      = wtap_snapshot_length(cf->wth);
-  if (cf->snap == 0) {
-    /* Snapshot length not known. */
-    cf->has_snap = FALSE;
-    cf->snap = WTAP_MAX_PACKET_SIZE;
-  } else
-    cf->has_snap = TRUE;
 
   /* Allocate a frame_data_sequence for the frames in this file */
   cf->frames = new_frame_data_sequence();
@@ -4236,12 +4230,6 @@ rescan_file(capture_file *cf, const char *fname, gboolean is_tempfile)
   cf->linktypes = g_array_sized_new(FALSE, FALSE, (guint) sizeof(int), 1);
 
   cf->snap      = wtap_snapshot_length(cf->wth);
-  if (cf->snap == 0) {
-    /* Snapshot length not known. */
-    cf->has_snap = FALSE;
-    cf->snap = WTAP_MAX_PACKET_SIZE;
-  } else
-    cf->has_snap = TRUE;
 
   name_ptr = g_filename_display_basename(cf->filename);