forked from osmocom/wireshark
The only LLC frame types that should be dissected based on their SAP or,
if the SAPs are SNAP, based on their ethertype are I frames and UI frames; others don't have payload to be dissected as belonging to other protocols. svn path=/trunk/; revision=555
This commit is contained in:
Guy Harris
parent
42aba512c6
commit
397b2be709
105
packet-llc.c
105
packet-llc.c
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@ -2,7 +2,7 @@
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* Routines for IEEE 802.2 LLC layer
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* Gilbert Ramirez <gramirez@tivoli.com>
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*
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* $Id: packet-llc.c,v 1.19 1999/08/10 20:05:40 guy Exp $
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* $Id: packet-llc.c,v 1.20 1999/08/23 22:47:13 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@unicom.net>
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@ -162,29 +162,59 @@ sap_dissect_func(u_char sap) {
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void
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capture_llc(const u_char *pd, int offset, guint32 cap_len, packet_counts *ld) {
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guint16 etype;
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int is_snap;
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int control;
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guint16 etype;
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capture_func_t *capture;
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is_snap = (pd[offset] == 0xAA) && (pd[offset+1] == 0xAA);
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/*
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* The low-order bit of the SSAP apparently determines whether this
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* is a request or a response. (RFC 1390, "Transmission of IP and
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* ARP over FDDI Networks", says
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*
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* Command frames are identified by having the low order
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* bit of the SSAP address reset to zero. Response frames
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* have the low order bit of the SSAP address set to one.
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*
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* and a page I've seen seems to imply that's part of 802.2.)
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*
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* XXX - that page also implies that LLC Type 2 always uses
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* extended operation, so we don't need to determine whether
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* it's basic or extended operation; is that the case?
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*/
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control = get_xdlc_control(pd, offset+2, pd[offset+1] & 0x01, TRUE);
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if (is_snap) {
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etype = (pd[offset+6] << 8) | pd[offset+7];
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offset += 8;
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capture_ethertype(etype, offset, pd, cap_len, ld);
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if (control == XDLC_I || control == (XDLC_U|XDLC_UI)) {
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/*
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* Unnumbered Information - analyze it based on
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* the Ethernet packet type.
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*/
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etype = (pd[offset+6] << 8) | pd[offset+7];
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offset += 8;
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capture_ethertype(etype, offset, pd, cap_len, ld);
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}
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}
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else {
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capture = sap_capture_func(pd[offset]);
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if (control == XDLC_I || control == (XDLC_U|XDLC_UI)) {
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/*
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* Unnumbered Information - analyze it based on
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* the DSAP.
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*/
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capture = sap_capture_func(pd[offset]);
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/* non-SNAP */
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offset += 3;
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/* non-SNAP */
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offset += 3;
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if (capture) {
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capture(pd, offset, cap_len, ld);
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if (capture) {
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capture(pd, offset, cap_len, ld);
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}
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else {
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ld->other++;
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}
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}
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else {
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ld->other++;
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}
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}
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}
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@ -193,8 +223,9 @@ dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
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proto_tree *llc_tree = NULL;
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proto_item *ti;
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guint16 etype;
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int is_snap;
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int control;
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guint16 etype;
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dissect_func_t *dissect;
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is_snap = (pd[offset] == 0xAA) && (pd[offset+1] == 0xAA);
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@ -226,17 +257,13 @@ dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
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* extended operation, so we don't need to determine whether
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* it's basic or extended operation; is that the case?
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*/
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dissect_xdlc_control(pd, offset+2, fd, llc_tree, hf_llc_ctrl,
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control = dissect_xdlc_control(pd, offset+2, fd, llc_tree, hf_llc_ctrl,
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pd[offset+1] & 0x01, TRUE);
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/*
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* XXX - do we want to append the SAP information to the stuff
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* "dissect_xdlc_control()" put in the COL_INFO column, rather
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* than overwriting it?
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*
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* XXX - we shouldn't, as far as I know, pass S frames to
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* "ethertype" or "dissect", and we may have to treat I frames
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* differently from U frames.
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*/
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if (is_snap) {
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if (check_col(fd, COL_INFO)) {
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@ -246,10 +273,17 @@ dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
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proto_tree_add_item(llc_tree, hf_llc_oui, offset+3, 3,
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pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5]);
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}
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etype = pntohs(&pd[offset+6]);
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offset += 8;
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/* w/o even checking, assume OUI is ethertype */
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ethertype(etype, offset, pd, fd, tree, llc_tree, hf_llc_type);
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if (control == (XDLC_U|XDLC_UI)) {
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/*
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* Unnumbered Information - dissect it based on
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* the Ethernet packet type.
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*/
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etype = pntohs(&pd[offset+6]);
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offset += 8;
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/* w/o even checking, assume OUI is ethertype */
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ethertype(etype, offset, pd, fd, tree, llc_tree,
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hf_llc_type);
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}
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}
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else {
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if (check_col(fd, COL_INFO)) {
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@ -257,18 +291,23 @@ dissect_llc(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
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val_to_str(pd[offset], sap_vals, "%02x"));
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}
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dissect = sap_dissect_func(pd[offset]);
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if (control == (XDLC_U|XDLC_UI)) {
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/*
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* Unnumbered Information - dissect it based on
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* the DSAP.
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*/
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dissect = sap_dissect_func(pd[offset]);
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/* non-SNAP */
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offset += 3;
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/* non-SNAP */
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offset += 3;
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if (dissect) {
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dissect(pd, offset, fd, tree);
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if (dissect) {
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dissect(pd, offset, fd, tree);
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}
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else {
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dissect_data(pd, offset, fd, tree);
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}
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}
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else {
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dissect_data(pd, offset, fd, tree);
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}
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}
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}
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76
xdlc.c
76
xdlc.c
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@ -2,7 +2,7 @@
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* Routines for use by various SDLC-derived protocols, such as HDLC
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* and its derivatives LAPB, IEEE 802.2 LLC, etc..
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*
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* $Id: xdlc.c,v 1.3 1999/08/16 05:54:32 guy Exp $
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* $Id: xdlc.c,v 1.4 1999/08/23 22:47:13 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@unicom.net>
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@ -74,31 +74,6 @@ static const value_string stype_vals[] = {
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{ 0, NULL }
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};
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/*
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* U-format modifiers.
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*/
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#define XDLC_U_MODIFIER_MASK 0xEC
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#define XDLC_UI 0x00 /* Unnumbered Information */
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#define XDLC_UP 0x20 /* Unnumbered Poll */
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#define XDLC_DISC 0x40 /* Disconnect (command) */
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#define XDLC_RD 0x40 /* Request Disconnect (response) */
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#define XDLC_UA 0x60 /* Unnumbered Acknowledge */
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#define XDLC_SNRM 0x80 /* Set Normal Response Mode */
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#define XDLC_TEST 0xC0 /* Test */
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#define XDLC_SIM 0x04 /* Set Initialization Mode (command) */
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#define XDLC_RIM 0x04 /* Request Initialization Mode (response) */
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#define XDLC_FRMR 0x84 /* Frame reject */
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#define XDLC_CFGR 0xC4 /* Configure */
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#define XDLC_SARM 0x0C /* Set Asynchronous Response Mode (command) */
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#define XDLC_DM 0x0C /* Disconnected mode (response) */
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#define XDLC_SABM 0x2C /* Set Asynchronous Balanced Mode */
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#define XDLC_SARME 0x4C /* Set Asynchronous Response Mode Extended */
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#define XDLC_SABME 0x6C /* Set Asynchronous Balanced Mode Extended */
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#define XDLC_RESET 0x8C /* Reset */
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#define XDLC_XID 0xAC /* Exchange identification */
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#define XDLC_SNRME 0xCC /* Set Normal Response Mode Extended */
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#define XDLC_BCN 0xEC /* Beacon */
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static const value_string modifier_short_vals_cmd[] = {
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{ XDLC_UI, "UI" },
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{ XDLC_UP, "UP" },
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@ -183,6 +158,47 @@ static const value_string modifier_vals_resp[] = {
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{ 0, NULL }
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};
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int
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get_xdlc_control(const u_char *pd, int offset, int is_response, int is_extended)
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{
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guint16 control;
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switch (pd[offset] & 0x03) {
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case XDLC_S:
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/*
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* Supervisory frame.
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*/
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return XDLC_S;
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case XDLC_U:
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/*
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* Unnumbered frame.
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*
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* XXX - is this two octets, with a P/F bit, in HDLC extended
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* operation? It's one octet in LLC, even though the control
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* field of I and S frames is a 2-byte extended-operation field
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* in LLC. Given that there are no sequence numbers in the
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* control field of a U frame, there doesn't appear to be any
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* need for it to be 2 bytes in extended operation.
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*/
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control = pd[offset];
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/*
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* Return the modifier as well as the XDLC_U bits, so that
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* our caller knows whether the packet is UI or something
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* else.
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*/
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return control & (XDLC_U_MODIFIER_MASK|0x03);
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default:
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/*
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* Information frame.
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*/
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return XDLC_I;
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}
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}
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int
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dissect_xdlc_control(const u_char *pd, int offset, frame_data *fd,
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proto_tree *xdlc_tree, int hf_xdlc_control,
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@ -331,7 +347,13 @@ dissect_xdlc_control(const u_char *pd, int offset, frame_data *fd,
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decode_boolean_bitfield(control, 0x03, 1*8,
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"Unnumbered frame", NULL));
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}
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return XDLC_U;
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/*
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* Return the modifier as well as the XDLC_U bits, so that
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* our caller knows whether the packet is UI or something
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* else.
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*/
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return control & (XDLC_U_MODIFIER_MASK|0x03);
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default:
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/*
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30
xdlc.h
30
xdlc.h
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@ -2,7 +2,7 @@
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* Define *DLC frame types, and routine to dissect the control field of
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* a *DLC frame.
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*
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* $Id: xdlc.h,v 1.1 1999/08/04 04:37:46 guy Exp $
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* $Id: xdlc.h,v 1.2 1999/08/23 22:47:13 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@unicom.net>
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@ -32,5 +32,33 @@
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#define XDLC_S 0x01 /* Supervisory frames */
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#define XDLC_U 0x03 /* Unnumbered frames */
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/*
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* U-format modifiers.
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*/
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#define XDLC_U_MODIFIER_MASK 0xEC
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#define XDLC_UI 0x00 /* Unnumbered Information */
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#define XDLC_UP 0x20 /* Unnumbered Poll */
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#define XDLC_DISC 0x40 /* Disconnect (command) */
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#define XDLC_RD 0x40 /* Request Disconnect (response) */
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#define XDLC_UA 0x60 /* Unnumbered Acknowledge */
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#define XDLC_SNRM 0x80 /* Set Normal Response Mode */
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#define XDLC_TEST 0xC0 /* Test */
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#define XDLC_SIM 0x04 /* Set Initialization Mode (command) */
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#define XDLC_RIM 0x04 /* Request Initialization Mode (response) */
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#define XDLC_FRMR 0x84 /* Frame reject */
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#define XDLC_CFGR 0xC4 /* Configure */
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#define XDLC_SARM 0x0C /* Set Asynchronous Response Mode (command) */
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#define XDLC_DM 0x0C /* Disconnected mode (response) */
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#define XDLC_SABM 0x2C /* Set Asynchronous Balanced Mode */
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#define XDLC_SARME 0x4C /* Set Asynchronous Response Mode Extended */
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#define XDLC_SABME 0x6C /* Set Asynchronous Balanced Mode Extended */
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#define XDLC_RESET 0x8C /* Reset */
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#define XDLC_XID 0xAC /* Exchange identification */
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#define XDLC_SNRME 0xCC /* Set Normal Response Mode Extended */
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#define XDLC_BCN 0xEC /* Beacon */
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int get_xdlc_control(const u_char *pd, int offset, int is_response,
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int extended);
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int dissect_xdlc_control(const u_char *pd, int offset, frame_data *fd,
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proto_tree *xdlc_tree, int hf_xdlc_control, int is_response, int extended);
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