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/* xdlc.c
* Routines for use by various SDLC-derived protocols, such as HDLC
* and its derivatives LAPB, IEEE 802.2 LLC, etc..
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <stdio.h>
#include <string.h>
#include <glib.h>
#include <epan/packet.h>
#include <epan/xdlc.h>
#include <wsutil/pint.h>
const value_string ftype_vals[] = {
{ XDLC_I, "Information frame" },
{ XDLC_S, "Supervisory frame" },
{ XDLC_U, "Unnumbered frame" },
{ 0, NULL }
};
const value_string stype_vals[] = {
{ XDLC_RR>>2, "Receiver ready" },
{ XDLC_RNR>>2, "Receiver not ready" },
{ XDLC_REJ>>2, "Reject" },
{ XDLC_SREJ>>2, "Selective reject" },
{ 0, NULL }
};
static const value_string modifier_short_vals_cmd[] = {
{ XDLC_UI, "UI" },
{ XDLC_UP, "UP" },
{ XDLC_DISC, "DISC" },
{ XDLC_UA, "UA" },
{ XDLC_SNRM, "SNRM" },
{ XDLC_SNRME, "SNRME" },
{ XDLC_TEST, "TEST" },
{ XDLC_SIM, "SIM" },
{ XDLC_FRMR, "FRMR" },
{ XDLC_CFGR, "CFGR" },
{ XDLC_SARM, "SARM" },
{ XDLC_SABM, "SABM" },
{ XDLC_SARME, "SARME" },
{ XDLC_SABME, "SABME" },
{ XDLC_RESET, "RESET" },
{ XDLC_XID, "XID" },
{ XDLC_SNRME, "SNRME" },
{ XDLC_BCN, "BCN" },
{ 0, NULL }
};
const value_string modifier_vals_cmd[] = {
{ XDLC_UI>>2, "Unnumbered Information" },
{ XDLC_UP>>2, "Unnumbered Poll" },
{ XDLC_DISC>>2, "Disconnect" },
{ XDLC_UA>>2, "Unnumbered Acknowledge" },
{ XDLC_SNRM>>2, "Set Normal Response Mode" },
{ XDLC_TEST>>2, "Test" },
{ XDLC_SIM>>2, "Set Initialization Mode" },
{ XDLC_FRMR>>2, "Frame reject" },
{ XDLC_CFGR>>2, "Configure" },
{ XDLC_SARM>>2, "Set Asynchronous Response Mode" },
{ XDLC_SABM>>2, "Set Asynchronous Balanced Mode" },
{ XDLC_SARME>>2, "Set Asynchronous Response Mode Extended" },
{ XDLC_SABME>>2, "Set Asynchronous Balanced Mode Extended" },
{ XDLC_RESET>>2, "Reset" },
{ XDLC_XID>>2, "Exchange identification" },
{ XDLC_SNRME>>2, "Set Normal Response Mode Extended" },
{ XDLC_BCN>>2, "Beacon" },
{ 0, NULL }
};
static const value_string modifier_short_vals_resp[] = {
{ XDLC_UI, "UI" },
{ XDLC_UP, "UP" },
{ XDLC_RD, "RD" },
{ XDLC_UA, "UA" },
{ XDLC_SNRM, "SNRM" },
{ XDLC_TEST, "TEST" },
{ XDLC_RIM, "RIM" },
{ XDLC_FRMR, "FRMR" },
{ XDLC_CFGR, "CFGR" },
{ XDLC_DM, "DM" },
{ XDLC_SABM, "SABM" },
{ XDLC_SARME, "SARME" },
{ XDLC_SABME, "SABME" },
{ XDLC_RESET, "RESET" },
{ XDLC_XID, "XID" },
{ XDLC_SNRME, "SNRME" },
{ XDLC_BCN, "BCN" },
{ 0, NULL }
};
const value_string modifier_vals_resp[] = {
{ XDLC_UI>>2, "Unnumbered Information" },
{ XDLC_UP>>2, "Unnumbered Poll" },
{ XDLC_RD>>2, "Request Disconnect" },
{ XDLC_UA>>2, "Unnumbered Acknowledge" },
{ XDLC_SNRM>>2, "Set Normal Response Mode" },
{ XDLC_TEST>>2, "Test" },
{ XDLC_RIM>>2, "Request Initialization Mode" },
{ XDLC_FRMR>>2, "Frame reject" },
{ XDLC_CFGR>>2, "Configure" },
{ XDLC_DM>>2, "Disconnected mode" },
{ XDLC_SABM>>2, "Set Asynchronous Balanced Mode" },
{ XDLC_SARME>>2, "Set Asynchronous Response Mode Extended" },
{ XDLC_SABME>>2, "Set Asynchronous Balanced Mode Extended" },
{ XDLC_RESET>>2, "Reset" },
{ XDLC_XID>>2, "Exchange identification" },
{ XDLC_SNRME>>2, "Set Normal Response Mode Extended" },
{ XDLC_BCN>>2, "Beacon" },
{ 0, NULL }
};
int
get_xdlc_control(const guint8 *pd, int offset, gboolean is_extended)
{
guint16 control;
switch (pd[offset] & 0x03) {
case XDLC_S:
default:
/*
* Supervisory or Information frame.
*/
if (is_extended)
control = pletoh16(&pd[offset]);
else
control = pd[offset];
break;
case XDLC_U:
/*
* Unnumbered frame.
*
* XXX - is this two octets, with a P/F bit, in HDLC extended
* operation? It's one octet in LLC, even though the control
* field of I and S frames is a 2-byte extended-operation field
* in LLC. Given that there are no sequence numbers in the
* control field of a U frame, there doesn't appear to be any
* need for it to be 2 bytes in extended operation.
*/
control = pd[offset];
break;
}
return control;
}
int
dissect_xdlc_control(tvbuff_t *tvb, int offset, packet_info *pinfo,
proto_tree *xdlc_tree, int hf_xdlc_control, gint ett_xdlc_control,
const xdlc_cf_items *cf_items_nonext, const xdlc_cf_items *cf_items_ext,
const value_string *u_modifier_short_vals_cmd,
const value_string *u_modifier_short_vals_resp, gboolean is_response,
gboolean is_extended, gboolean append_info)
{
guint16 control;
int control_len;
const xdlc_cf_items *cf_items;
const char *control_format;
guint16 poll_final;
char *info;
proto_tree *tc, *control_tree;
const gchar *frame_type = NULL;
const gchar *modifier;
info=(char *)wmem_alloc(pinfo->pool, 80);
switch (tvb_get_guint8(tvb, offset) & 0x03) {
case XDLC_S:
/*
* Supervisory frame.
*/
if (is_extended) {
control = tvb_get_letohs(tvb, offset);
control_len = 2;
cf_items = cf_items_ext;
control_format = "Control field: %s (0x%04X)";
} else {
control = tvb_get_guint8(tvb, offset);
control_len = 1;
cf_items = cf_items_nonext;
control_format = "Control field: %s (0x%02X)";
}
switch (control & XDLC_S_FTYPE_MASK) {
case XDLC_RR:
frame_type = "RR";
break;
case XDLC_RNR:
frame_type = "RNR";
break;
case XDLC_REJ:
frame_type = "REJ";
break;
case XDLC_SREJ:
frame_type = "SREJ";
break;
}
if (is_extended) {
poll_final = (control & XDLC_P_F_EXT);
snprintf(info, 80, "S%s, func=%s, N(R)=%u",
(poll_final ?
(is_response ? " F" : " P") :
""),
frame_type,
(control & XDLC_N_R_EXT_MASK) >> XDLC_N_R_EXT_SHIFT);
} else {
poll_final = (control & XDLC_P_F);
snprintf(info, 80, "S%s, func=%s, N(R)=%u",
(poll_final ?
(is_response ? " F" : " P") :
""),
frame_type,
(control & XDLC_N_R_MASK) >> XDLC_N_R_SHIFT);
}
if (append_info) {
col_append_str(pinfo->cinfo, COL_INFO, ", ");
col_append_str(pinfo->cinfo, COL_INFO, info);
} else {
col_add_str(pinfo->cinfo, COL_INFO, info);
}
if (xdlc_tree) {
tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb,
offset, control_len, control, control_format, info, control);
control_tree = proto_item_add_subtree(tc, ett_xdlc_control);
proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_r,
tvb, offset, control_len, control);
if (poll_final) {
proto_tree_add_boolean(control_tree,
(is_response ? *cf_items->hf_xdlc_f :
*cf_items->hf_xdlc_p),
tvb, offset, control_len, control);
}
proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_s_ftype,
tvb, offset, control_len, control);
/* This will always say it's a supervisory frame */
proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_s_u,
tvb, offset, control_len, control);
}
break;
case XDLC_U:
/*
* Unnumbered frame.
*
* XXX - is this two octets, with a P/F bit, in HDLC extended
* operation? It's one octet in LLC, even though the control
* field of I and S frames is a 2-byte extended-operation field
* in LLC. Given that there are no sequence numbers in the
* control field of a U frame, there doesn't appear to be any
* need for it to be 2 bytes in extended operation.
*/
if (u_modifier_short_vals_cmd == NULL)
u_modifier_short_vals_cmd = modifier_short_vals_cmd;
if (u_modifier_short_vals_resp == NULL)
u_modifier_short_vals_resp = modifier_short_vals_resp;
control = tvb_get_guint8(tvb, offset);
control_len = 1;
cf_items = cf_items_nonext;
control_format = "Control field: %s (0x%02X)";
if (is_response) {
modifier = val_to_str(control & XDLC_U_MODIFIER_MASK,
u_modifier_short_vals_resp, "Unknown");
} else {
modifier = val_to_str(control & XDLC_U_MODIFIER_MASK,
u_modifier_short_vals_cmd, "Unknown");
}
poll_final = (control & XDLC_P_F);
snprintf(info, 80, "U%s, func=%s",
(poll_final ?
(is_response ? " F" : " P") :
""),
modifier);
if (append_info) {
col_append_str(pinfo->cinfo, COL_INFO, ", ");
col_append_str(pinfo->cinfo, COL_INFO, info);
} else {
col_add_str(pinfo->cinfo, COL_INFO, info);
}
if (xdlc_tree) {
tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb,
offset, control_len, control, control_format, info, control);
control_tree = proto_item_add_subtree(tc, ett_xdlc_control);
if (poll_final) {
proto_tree_add_boolean(control_tree,
(is_response ? *cf_items->hf_xdlc_f:
*cf_items->hf_xdlc_p),
tvb, offset, control_len, control);
}
proto_tree_add_uint(control_tree,
(is_response ? *cf_items->hf_xdlc_u_modifier_resp :
*cf_items->hf_xdlc_u_modifier_cmd),
tvb, offset, control_len, control);
/* This will always say it's an unnumbered frame */
proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_s_u,
tvb, offset, control_len, control);
}
break;
default:
/*
* Information frame.
*/
if (is_extended) {
control = tvb_get_letohs(tvb, offset);
control_len = 2;
cf_items = cf_items_ext;
control_format = "Control field: %s (0x%04X)";
poll_final = (control & XDLC_P_F_EXT);
snprintf(info, 80, "I%s, N(R)=%u, N(S)=%u",
((control & XDLC_P_F_EXT) ? " P" : ""),
(control & XDLC_N_R_EXT_MASK) >> XDLC_N_R_EXT_SHIFT,
(control & XDLC_N_S_EXT_MASK) >> XDLC_N_S_EXT_SHIFT);
} else {
control = tvb_get_guint8(tvb, offset);
control_len = 1;
cf_items = cf_items_nonext;
control_format = "Control field: %s (0x%02X)";
poll_final = (control & XDLC_P_F);
snprintf(info, 80, "I%s, N(R)=%u, N(S)=%u",
((control & XDLC_P_F) ? " P" : ""),
(control & XDLC_N_R_MASK) >> XDLC_N_R_SHIFT,
(control & XDLC_N_S_MASK) >> XDLC_N_S_SHIFT);
}
if (append_info) {
col_append_str(pinfo->cinfo, COL_INFO, ", ");
col_append_str(pinfo->cinfo, COL_INFO, info);
} else {
col_add_str(pinfo->cinfo, COL_INFO, info);
}
if (xdlc_tree) {
tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb,
offset, control_len, control, control_format, info, control);
control_tree = proto_item_add_subtree(tc, ett_xdlc_control);
proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_r,
tvb, offset, control_len, control);
proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_s,
tvb, offset, control_len, control);
if (poll_final) {
proto_tree_add_boolean(control_tree, *cf_items->hf_xdlc_p,
tvb, offset, control_len, control);
}
/* This will always say it's an information frame */
proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_i,
tvb, offset, control_len, control);
}
break;
}
return control;
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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