path: root/print-llc.c

/*
 * Copyright (c) 1992, 1993, 1994, 1995, 1996, 1997
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Code by Matt Thomas, Digital Equipment Corporation
 *	with an awful lot of hacking by Jeffrey Mogul, DECWRL
 */

/* \summary: IEEE 802.2 LLC printer */

#include <config.h>

#include "netdissect-stdinc.h"

#include "netdissect.h"
#include "addrtoname.h"
#include "extract.h"

#include "llc.h"
#include "ethertype.h"
#include "oui.h"

static const struct tok llc_values[] = {
        { LLCSAP_NULL,     "Null" },
        { LLCSAP_GLOBAL,   "Global" },
        { LLCSAP_8021B_I,  "802.1B I" },
        { LLCSAP_8021B_G,  "802.1B G" },
        { LLCSAP_IP,       "IP" },
        { LLCSAP_SNA,      "SNA" },
        { LLCSAP_PROWAYNM, "ProWay NM" },
        { LLCSAP_8021D,    "STP" },
        { LLCSAP_RS511,    "RS511" },
        { LLCSAP_ISO8208,  "ISO8208" },
        { LLCSAP_PROWAY,   "ProWay" },
        { LLCSAP_SNAP,     "SNAP" },
        { LLCSAP_IPX,      "IPX" },
        { LLCSAP_NETBEUI,  "NetBeui" },
        { LLCSAP_ISONS,    "OSI" },
        { 0,               NULL },
};

static const struct tok llc_cmd_values[] = {
	{ LLC_UI,	"ui" },
	{ LLC_TEST,	"test" },
	{ LLC_XID,	"xid" },
	{ LLC_UA,	"ua" },
	{ LLC_DISC,	"disc" },
	{ LLC_DM,	"dm" },
	{ LLC_SABME,	"sabme" },
	{ LLC_FRMR,	"frmr" },
	{ 0,		NULL }
};

static const struct tok llc_flag_values[] = {
        { 0, "Command" },
        { LLC_GSAP, "Response" },
        { LLC_U_POLL, "Poll" },
        { LLC_GSAP|LLC_U_POLL, "Final" },
        { LLC_IS_POLL, "Poll" },
        { LLC_GSAP|LLC_IS_POLL, "Final" },
	{ 0, NULL }
};


static const struct tok llc_ig_flag_values[] = {
        { 0, "Individual" },
        { LLC_IG, "Group" },
	{ 0, NULL }
};


static const struct tok llc_supervisory_values[] = {
        { 0, "Receiver Ready" },
        { 1, "Receiver not Ready" },
        { 2, "Reject" },
	{ 0,             NULL }
};


static const struct tok cisco_values[] = {
	{ PID_CISCO_CDP, "CDP" },
	{ PID_CISCO_VTP, "VTP" },
	{ PID_CISCO_DTP, "DTP" },
	{ PID_CISCO_UDLD, "UDLD" },
	{ PID_CISCO_PVST, "PVST" },
	{ PID_CISCO_VLANBRIDGE, "VLAN Bridge" },
	{ 0,             NULL }
};

static const struct tok bridged_values[] = {
	{ PID_RFC2684_ETH_FCS,     "Ethernet + FCS" },
	{ PID_RFC2684_ETH_NOFCS,   "Ethernet w/o FCS" },
	{ PID_RFC2684_802_4_FCS,   "802.4 + FCS" },
	{ PID_RFC2684_802_4_NOFCS, "802.4 w/o FCS" },
	{ PID_RFC2684_802_5_FCS,   "Token Ring + FCS" },
	{ PID_RFC2684_802_5_NOFCS, "Token Ring w/o FCS" },
	{ PID_RFC2684_FDDI_FCS,    "FDDI + FCS" },
	{ PID_RFC2684_FDDI_NOFCS,  "FDDI w/o FCS" },
	{ PID_RFC2684_802_6_FCS,   "802.6 + FCS" },
	{ PID_RFC2684_802_6_NOFCS, "802.6 w/o FCS" },
	{ PID_RFC2684_BPDU,        "BPDU" },
	{ 0,                       NULL },
};

static const struct tok null_values[] = {
	{ 0,             NULL }
};

struct oui_tok {
	uint32_t	oui;
	const struct tok *tok;
};

static const struct oui_tok oui_to_tok[] = {
	{ OUI_ENCAP_ETHER, ethertype_values },
	{ OUI_CISCO_90, ethertype_values },	/* uses some Ethertype values */
	{ OUI_APPLETALK, ethertype_values },	/* uses some Ethertype values */
	{ OUI_CISCO, cisco_values },
	{ OUI_RFC2684, bridged_values },	/* bridged, RFC 2427 FR or RFC 2864 ATM */
	{ 0, NULL }
};

/*
 * If we printed information about the payload, returns the length of the LLC
 * header, plus the length of any SNAP header following it.
 *
 * Otherwise (for example, if the packet has unknown SAPs or has a SNAP
 * header with an unknown OUI/PID combination), returns the *negative*
 * of that value.
 */
int
llc_print(netdissect_options *ndo, const u_char *p, u_int length, u_int caplen,
	  const struct lladdr_info *src, const struct lladdr_info *dst)
{
	uint8_t dsap_field, dsap, ssap_field, ssap;
	uint16_t control;
	int hdrlen;
	int is_u;

	ndo->ndo_protocol = "llc";
	if (caplen < 3) {
		nd_print_trunc(ndo);
		ND_DEFAULTPRINT((const u_char *)p, caplen);
		return (caplen);
	}
	if (length < 3) {
		nd_print_trunc(ndo);
		ND_DEFAULTPRINT((const u_char *)p, caplen);
		return (length);
	}

	dsap_field = GET_U_1(p);
	ssap_field = GET_U_1(p + 1);

	/*
	 * OK, what type of LLC frame is this?  The length
	 * of the control field depends on that - I frames
	 * have a two-byte control field, and U frames have
	 * a one-byte control field.
	 */
	control = GET_U_1(p + 2);
	if ((control & LLC_U_FMT) == LLC_U_FMT) {
		/*
		 * U frame.
		 */
		is_u = 1;
		hdrlen = 3;	/* DSAP, SSAP, 1-byte control field */
	} else {
		/*
		 * The control field in I and S frames is
		 * 2 bytes...
		 */
		if (caplen < 4) {
			nd_print_trunc(ndo);
			ND_DEFAULTPRINT((const u_char *)p, caplen);
			return (caplen);
		}
		if (length < 4) {
			nd_print_trunc(ndo);
			ND_DEFAULTPRINT((const u_char *)p, caplen);
			return (length);
		}

		/*
		 * ...and is little-endian.
		 */
		control = GET_LE_U_2(p + 2);
		is_u = 0;
		hdrlen = 4;	/* DSAP, SSAP, 2-byte control field */
	}

	if (ssap_field == LLCSAP_GLOBAL && dsap_field == LLCSAP_GLOBAL) {
		/*
		 * This is an Ethernet_802.3 IPX frame; it has an
		 * 802.3 header (i.e., an Ethernet header where the
		 * type/length field is <= MAX_ETHERNET_LENGTH_VAL,
		 * i.e. it's a length field, not a type field), but
		 * has no 802.2 header - the IPX packet starts right
		 * after the Ethernet header, with a signature of two
		 * bytes of 0xFF (which is LLCSAP_GLOBAL).
		 *
		 * (It might also have been an Ethernet_802.3 IPX at
		 * one time, but got bridged onto another network,
		 * such as an 802.11 network; this has appeared in at
		 * least one capture file.)
		 */

            if (ndo->ndo_eflag)
		ND_PRINT("IPX 802.3: ");

            ipx_print(ndo, p, length);
            return (0);		/* no LLC header */
	}

	dsap = dsap_field & ~LLC_IG;
	ssap = ssap_field & ~LLC_GSAP;

	if (ndo->ndo_eflag) {
                ND_PRINT("LLC, dsap %s (0x%02x) %s, ssap %s (0x%02x) %s",
                       tok2str(llc_values, "Unknown", dsap),
                       dsap,
                       tok2str(llc_ig_flag_values, "Unknown", dsap_field & LLC_IG),
                       tok2str(llc_values, "Unknown", ssap),
                       ssap,
                       tok2str(llc_flag_values, "Unknown", ssap_field & LLC_GSAP));

		if (is_u) {
			ND_PRINT(", ctrl 0x%02x: ", control);
		} else {
			ND_PRINT(", ctrl 0x%04x: ", control);
		}
	}

	/*
	 * Skip LLC header.
	 */
	p += hdrlen;
	length -= hdrlen;
	caplen -= hdrlen;

	if (ssap == LLCSAP_SNAP && dsap == LLCSAP_SNAP
	    && control == LLC_UI) {
		/*
		 * XXX - what *is* the right bridge pad value here?
		 * Does anybody ever bridge one form of LAN traffic
		 * over a networking type that uses 802.2 LLC?
		 */
		if (!snap_print(ndo, p, length, caplen, src, dst, 2)) {
			/*
			 * Unknown packet type; tell our caller, by
			 * returning a negative value, so they
			 * can print the raw packet.
			 */
			return (-(hdrlen + 5));	/* include LLC and SNAP header */
		} else
			return (hdrlen + 5);	/* include LLC and SNAP header */
	}

	if (ssap == LLCSAP_8021D && dsap == LLCSAP_8021D &&
	    control == LLC_UI) {
		stp_print(ndo, p, length);
		return (hdrlen);
	}

	if (ssap == LLCSAP_IP && dsap == LLCSAP_IP &&
	    control == LLC_UI) {
		/*
		 * This is an RFC 948-style IP packet, with
		 * an 802.3 header and an 802.2 LLC header
		 * with the source and destination SAPs being
		 * the IP SAP.
		 */
		ip_print(ndo, p, length);
		return (hdrlen);
	}

	if (ssap == LLCSAP_IPX && dsap == LLCSAP_IPX &&
	    control == LLC_UI) {
		/*
		 * This is an Ethernet_802.2 IPX frame, with an 802.3
		 * header and an 802.2 LLC header with the source and
		 * destination SAPs being the IPX SAP.
		 */
                if (ndo->ndo_eflag)
                        ND_PRINT("IPX 802.2: ");

		ipx_print(ndo, p, length);
		return (hdrlen);
	}

#ifdef ENABLE_SMB
	if (ssap == LLCSAP_NETBEUI && dsap == LLCSAP_NETBEUI
	    && (!(control & LLC_S_FMT) || control == LLC_U_FMT)) {
		/*
		 * we don't actually have a full netbeui parser yet, but the
		 * smb parser can handle many smb-in-netbeui packets, which
		 * is very useful, so we call that
		 *
		 * We don't call it for S frames, however, just I frames
		 * (which are frames that don't have the low-order bit,
		 * LLC_S_FMT, set in the first byte of the control field)
		 * and UI frames (whose control field is just 3, LLC_U_FMT).
		 */
		netbeui_print(ndo, control, p, length);
		return (hdrlen);
	}
#endif
	if (ssap == LLCSAP_ISONS && dsap == LLCSAP_ISONS
	    && control == LLC_UI) {
		isoclns_print(ndo, p, length);
		return (hdrlen);
	}

	if (!ndo->ndo_eflag) {
		if (ssap == dsap) {
			if (src == NULL || dst == NULL)
				ND_PRINT("%s ", tok2str(llc_values, "Unknown DSAP 0x%02x", dsap));
			else
				ND_PRINT("%s > %s %s ",
						(src->addr_string)(ndo, src->addr),
						(dst->addr_string)(ndo, dst->addr),
						tok2str(llc_values, "Unknown DSAP 0x%02x", dsap));
		} else {
			if (src == NULL || dst == NULL)
				ND_PRINT("%s > %s ",
                                        tok2str(llc_values, "Unknown SSAP 0x%02x", ssap),
					tok2str(llc_values, "Unknown DSAP 0x%02x", dsap));
			else
				ND_PRINT("%s %s > %s %s ",
					(src->addr_string)(ndo, src->addr),
                                        tok2str(llc_values, "Unknown SSAP 0x%02x", ssap),
					(dst->addr_string)(ndo, dst->addr),
					tok2str(llc_values, "Unknown DSAP 0x%02x", dsap));
		}
	}

	if (is_u) {
		ND_PRINT("Unnumbered, %s, Flags [%s], length %u",
                       tok2str(llc_cmd_values, "%02x", LLC_U_CMD(control)),
                       tok2str(llc_flag_values,"?",(ssap_field & LLC_GSAP) | (control & LLC_U_POLL)),
                       length + hdrlen);

		if ((control & ~LLC_U_POLL) == LLC_XID) {
			if (length == 0) {
				/*
				 * XID with no payload.
				 * This could, for example, be an SNA
				 * "short form" XID.
                                 */
				return (hdrlen);
			}
			if (caplen < 1) {
				nd_print_trunc(ndo);
				if (caplen > 0)
					ND_DEFAULTPRINT((const u_char *)p, caplen);
				return (hdrlen);
			}
			if (GET_U_1(p) == LLC_XID_FI) {
				if (caplen < 3 || length < 3) {
					nd_print_trunc(ndo);
					if (caplen > 0)
						ND_DEFAULTPRINT((const u_char *)p, caplen);
				} else
					ND_PRINT(": %02x %02x",
						  GET_U_1(p + 1),
						  GET_U_1(p + 2));
				return (hdrlen);
			}
		}
	} else {
		if ((control & LLC_S_FMT) == LLC_S_FMT) {
			ND_PRINT("Supervisory, %s, rcv seq %u, Flags [%s], length %u",
				tok2str(llc_supervisory_values,"?",LLC_S_CMD(control)),
				LLC_IS_NR(control),
				tok2str(llc_flag_values,"?",(ssap_field & LLC_GSAP) | (control & LLC_IS_POLL)),
                                length + hdrlen);
			return (hdrlen);	/* no payload to print */
		} else {
			ND_PRINT("Information, send seq %u, rcv seq %u, Flags [%s], length %u",
				LLC_I_NS(control),
				LLC_IS_NR(control),
				tok2str(llc_flag_values,"?",(ssap_field & LLC_GSAP) | (control & LLC_IS_POLL)),
                                length + hdrlen);
		}
	}
	return (-hdrlen);
}

static const struct tok *
oui_to_struct_tok(uint32_t orgcode)
{
	const struct tok *tok = null_values;
	const struct oui_tok *otp;

	for (otp = &oui_to_tok[0]; otp->tok != NULL; otp++) {
		if (otp->oui == orgcode) {
			tok = otp->tok;
			break;
		}
	}
	return (tok);
}

int
snap_print(netdissect_options *ndo, const u_char *p, u_int length, u_int caplen,
	const struct lladdr_info *src, const struct lladdr_info *dst,
	u_int bridge_pad)
{
	uint32_t orgcode;
	u_short et;
	int ret;

	ndo->ndo_protocol = "snap";
	ND_TCHECK_5(p);
	if (caplen < 5 || length < 5)
		goto trunc;
	orgcode = GET_BE_U_3(p);
	et = GET_BE_U_2(p + 3);

	if (ndo->ndo_eflag) {
		/*
		 * Somebody's already printed the MAC addresses, if there
		 * are any, so just print the SNAP header, not the MAC
		 * addresses.
		 */
		ND_PRINT("oui %s (0x%06x), %s %s (0x%04x), length %u: ",
		     tok2str(oui_values, "Unknown", orgcode),
		     orgcode,
		     (orgcode == 0x000000 ? "ethertype" : "pid"),
		     tok2str(oui_to_struct_tok(orgcode), "Unknown", et),
		     et, length - 5);
	}
	p += 5;
	length -= 5;
	caplen -= 5;

	switch (orgcode) {
	case OUI_ENCAP_ETHER:
	case OUI_CISCO_90:
		/*
		 * This is an encapsulated Ethernet packet,
		 * or a packet bridged by some piece of
		 * Cisco hardware; the protocol ID is
		 * an Ethernet protocol type.
		 */
		ret = ethertype_print(ndo, et, p, length, caplen, src, dst);
		if (ret)
			return (ret);
		break;

	case OUI_APPLETALK:
		if (et == ETHERTYPE_ATALK) {
			/*
			 * No, I have no idea why Apple used one
			 * of their own OUIs, rather than
			 * 0x000000, and an Ethernet packet
			 * type, for Appletalk data packets,
			 * but used 0x000000 and an Ethernet
			 * packet type for AARP packets.
			 */
			ret = ethertype_print(ndo, et, p, length, caplen, src, dst);
			if (ret)
				return (ret);
		}
		break;

	case OUI_CISCO:
                switch (et) {
                case PID_CISCO_CDP:
                        cdp_print(ndo, p, length);
                        return (1);
                case PID_CISCO_DTP:
                        dtp_print(ndo, p, length);
                        return (1);
                case PID_CISCO_UDLD:
                        udld_print(ndo, p, length);
                        return (1);
                case PID_CISCO_VTP:
                        vtp_print(ndo, p, length);
                        return (1);
                case PID_CISCO_PVST:
                case PID_CISCO_VLANBRIDGE:
                        stp_print(ndo, p, length);
                        return (1);
                default:
                        break;
                }
		break;

	case OUI_RFC2684:
		switch (et) {

		case PID_RFC2684_ETH_FCS:
		case PID_RFC2684_ETH_NOFCS:
			/*
			 * XXX - remove the last two bytes for
			 * PID_RFC2684_ETH_FCS?
			 */
			/*
			 * Skip the padding.
			 */
			ND_TCHECK_LEN(p, bridge_pad);
			caplen -= bridge_pad;
			length -= bridge_pad;
			p += bridge_pad;

			/*
			 * What remains is an Ethernet packet.
			 */
			ether_print(ndo, p, length, caplen, NULL, NULL);
			return (1);

		case PID_RFC2684_802_5_FCS:
		case PID_RFC2684_802_5_NOFCS:
			/*
			 * XXX - remove the last two bytes for
			 * PID_RFC2684_ETH_FCS?
			 */
			/*
			 * Skip the padding, but not the Access
			 * Control field.
			 */
			ND_TCHECK_LEN(p, bridge_pad);
			caplen -= bridge_pad;
			length -= bridge_pad;
			p += bridge_pad;

			/*
			 * What remains is an 802.5 Token Ring
			 * packet.
			 */
			token_print(ndo, p, length, caplen);
			return (1);

		case PID_RFC2684_FDDI_FCS:
		case PID_RFC2684_FDDI_NOFCS:
			/*
			 * XXX - remove the last two bytes for
			 * PID_RFC2684_ETH_FCS?
			 */
			/*
			 * Skip the padding.
			 */
			ND_TCHECK_LEN(p, bridge_pad + 1);
			caplen -= bridge_pad + 1;
			length -= bridge_pad + 1;
			p += bridge_pad + 1;

			/*
			 * What remains is an FDDI packet.
			 */
			fddi_print(ndo, p, length, caplen);
			return (1);

		case PID_RFC2684_BPDU:
			stp_print(ndo, p, length);
			return (1);
		}
	}
	if (!ndo->ndo_eflag) {
		/*
		 * Nobody printed the link-layer addresses, so print them, if
		 * we have any.
		 */
		if (src != NULL && dst != NULL) {
			ND_PRINT("%s > %s ",
				(src->addr_string)(ndo, src->addr),
				(dst->addr_string)(ndo, dst->addr));
		}
		/*
		 * Print the SNAP header, but if the OUI is 000000, don't
		 * bother printing it, and report the PID as being an
		 * ethertype.
		 */
		if (orgcode == 0x000000) {
			ND_PRINT("SNAP, ethertype %s (0x%04x), length %u: ",
			     tok2str(ethertype_values, "Unknown", et),
			     et, length);
		} else {
			ND_PRINT("SNAP, oui %s (0x%06x), pid %s (0x%04x), length %u: ",
			     tok2str(oui_values, "Unknown", orgcode),
			     orgcode,
			     tok2str(oui_to_struct_tok(orgcode), "Unknown", et),
			     et, length);
		}
	}
	return (0);

trunc:
	nd_print_trunc(ndo);
	return (1);
}