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/* atm.c
*
* Wiretap Library
* Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include "wtap-int.h"
#include "atm.h"
/*
* Routines to use with ATM capture file types that don't include information
* about the *type* of ATM traffic (or, at least, where we haven't found
* that information).
*
* We assume the traffic is AAL5, unless it's VPI 0/VCI 5, in which case
* we assume it's the signalling AAL.
*/
void
atm_guess_traffic_type(wtap_rec *rec, const guint8 *pd)
{
/*
* Start out assuming nothing other than that it's AAL5.
*/
rec->rec_header.packet_header.pseudo_header.atm.aal = AAL_5;
rec->rec_header.packet_header.pseudo_header.atm.type = TRAF_UNKNOWN;
rec->rec_header.packet_header.pseudo_header.atm.subtype = TRAF_ST_UNKNOWN;
if (rec->rec_header.packet_header.pseudo_header.atm.vpi == 0) {
/*
* Traffic on some PVCs with a VPI of 0 and certain
* VCIs is of particular types.
*/
switch (rec->rec_header.packet_header.pseudo_header.atm.vci) {
case 5:
/*
* Signalling AAL.
*/
rec->rec_header.packet_header.pseudo_header.atm.aal = AAL_SIGNALLING;
return;
case 16:
/*
* ILMI.
*/
rec->rec_header.packet_header.pseudo_header.atm.type = TRAF_ILMI;
return;
}
}
/*
* OK, we can't tell what it is based on the VPI/VCI; try
* guessing based on the contents, if we have enough data
* to guess.
*/
if (rec->rec_header.packet_header.caplen >= 3) {
if (pd[0] == 0xaa && pd[1] == 0xaa && pd[2] == 0x03) {
/*
* Looks like a SNAP header; assume it's LLC
* multiplexed RFC 1483 traffic.
*/
rec->rec_header.packet_header.pseudo_header.atm.type = TRAF_LLCMX;
} else if ((rec->rec_header.packet_header.pseudo_header.atm.aal5t_len && rec->rec_header.packet_header.pseudo_header.atm.aal5t_len < 16) ||
rec->rec_header.packet_header.caplen < 16) {
/*
* As this cannot be a LANE Ethernet frame (less
* than 2 bytes of LANE header + 14 bytes of
* Ethernet header) we can try it as a SSCOP frame.
*/
rec->rec_header.packet_header.pseudo_header.atm.aal = AAL_SIGNALLING;
} else if (pd[0] == 0x83 || pd[0] == 0x81) {
/*
* MTP3b headers often encapsulate
* a SCCP or MTN in the 3G network.
* This should cause 0x83 or 0x81
* in the first byte.
*/
rec->rec_header.packet_header.pseudo_header.atm.aal = AAL_SIGNALLING;
} else {
/*
* Assume it's LANE.
*/
rec->rec_header.packet_header.pseudo_header.atm.type = TRAF_LANE;
atm_guess_lane_type(rec, pd);
}
} else {
/*
* Not only VCI 5 is used for signaling. It might be
* one of these VCIs.
*/
rec->rec_header.packet_header.pseudo_header.atm.aal = AAL_SIGNALLING;
}
}
void
atm_guess_lane_type(wtap_rec *rec, const guint8 *pd)
{
if (rec->rec_header.packet_header.caplen >= 2) {
if (pd[0] == 0xff && pd[1] == 0x00) {
/*
* Looks like LE Control traffic.
*/
rec->rec_header.packet_header.pseudo_header.atm.subtype = TRAF_ST_LANE_LE_CTRL;
} else {
/*
* XXX - Ethernet, or Token Ring?
* Assume Ethernet for now; if we see earlier
* LANE traffic, we may be able to figure out
* the traffic type from that, but there may
* still be situations where the user has to
* tell us.
*/
rec->rec_header.packet_header.pseudo_header.atm.subtype = TRAF_ST_LANE_802_3;
}
}
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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