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The LAPB dissector can be called from the Ethernet dissector; don't 

assume we have an X.25 pseudo-header.

svn path=/trunk/; revision=8547
This commit is contained in:
Guy Harris 2003-09-26 08:19:55 +00:00
parent 2d33b62811
commit 1085de3d7a
1 changed files with 62 additions and 17 deletions
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79
packet-lapb.c
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@ -2,7 +2,7 @@
* Routines for lapb frame disassembly
* Olivier Abad <oabad@noos.fr>
*
* $Id: packet-lapb.c,v 1.39 2003/09/02 19:18:52 guy Exp $
* $Id: packet-lapb.c,v 1.40 2003/09/26 08:19:55 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
@ -41,6 +41,7 @@ static gint ett_lapb = -1;
static gint ett_lapb_control = -1;
static dissector_handle_t x25_dir_handle;
static dissector_handle_t x25_handle;
static void
dissect_lapb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
@ -55,17 +56,28 @@ dissect_lapb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
if (check_col(pinfo->cinfo, COL_INFO))
col_clear(pinfo->cinfo, COL_INFO);
if (pinfo->pseudo_header->x25.flags & FROM_DCE) {
if(check_col(pinfo->cinfo, COL_RES_DL_DST))
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
}
else {
if(check_col(pinfo->cinfo, COL_RES_DL_DST))
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
switch (pinfo->p2p_dir) {
case P2P_DIR_SENT:
if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE");
if(check_col(pinfo->cinfo, COL_RES_DL_DST))
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
break;
case P2P_DIR_RECV:
if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
if(check_col(pinfo->cinfo, COL_RES_DL_DST))
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
break;
default:
if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "N/A");
if(check_col(pinfo->cinfo, COL_RES_DL_DST))
col_set_str(pinfo->cinfo, COL_RES_DL_DST, "N/A");
break;
}
byte0 = tvb_get_guint8(tvb, 0);
@ -80,11 +92,32 @@ dissect_lapb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
return;
}
if (((pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 == 0x01) ||
(!(pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 == 0x03))
is_response = TRUE;
else
switch (pinfo->p2p_dir) {
case P2P_DIR_SENT:
if (byte0 == 0x03)
is_response = TRUE;
else
is_response = FALSE;
break;
case P2P_DIR_RECV:
if (byte0 == 0x01)
is_response = TRUE;
else
is_response = FALSE;
break;
default:
/*
* XXX - should we base this on the source and destination
* addresses? The problem is that we can tell one direction
* from another with that, but we can't say which is DTE->DCE
* and which is DCE->DTE.
*/
is_response = FALSE;
break;
}
if (tree) {
ti = proto_tree_add_protocol_format(tree, proto_lapb, tvb, 0, 2,
@ -101,8 +134,18 @@ dissect_lapb(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
/* not end of frame ==> X.25 */
if (tvb_reported_length(tvb) > 2) {
next_tvb = tvb_new_subset(tvb, 2, -1, -1);
next_tvb = tvb_new_subset(tvb, 2, -1, -1);
switch (pinfo->p2p_dir) {
case P2P_DIR_SENT:
case P2P_DIR_RECV:
call_dissector(x25_dir_handle, next_tvb, pinfo, tree);
break;
default:
call_dissector(x25_handle, next_tvb, pinfo, tree);
break;
}
}
}
@ -137,10 +180,12 @@ proto_reg_handoff_lapb(void)
dissector_handle_t lapb_handle;
/*
* Get a handle for the X.25 dissector; we will be getting an
* X.25 pseudo-header, so call the dissector that can handle it.
* Get handles for the X.25 dissectors; we don't get an X.25
* pseudo-header for LAPB-over-Ethernet, but we do get it
* for raw LAPB.
*/
x25_dir_handle = find_dissector("x.25_dir");
x25_handle = find_dissector("x.25");
lapb_handle = find_dissector("lapb");
dissector_add("wtap_encap", WTAP_ENCAP_LAPB, lapb_handle);