nexmon – Rev 1
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/*
* Copyright (c) 1988, 1989, 1990, 1991, 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.
*/
#define NETDISSECT_REWORKED
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <tcpdump-stdinc.h>
#include "interface.h"
#include "addrtoname.h"
#include "ethertype.h"
#include "extract.h"
#include "ether.h"
/*
* For captures on Linux cooked sockets, we construct a fake header
* that includes:
*
* a 2-byte "packet type" which is one of:
*
* LINUX_SLL_HOST packet was sent to us
* LINUX_SLL_BROADCAST packet was broadcast
* LINUX_SLL_MULTICAST packet was multicast
* LINUX_SLL_OTHERHOST packet was sent to somebody else
* LINUX_SLL_OUTGOING packet was sent *by* us;
*
* a 2-byte Ethernet protocol field;
*
* a 2-byte link-layer type;
*
* a 2-byte link-layer address length;
*
* an 8-byte source link-layer address, whose actual length is
* specified by the previous value.
*
* All fields except for the link-layer address are in network byte order.
*
* DO NOT change the layout of this structure, or change any of the
* LINUX_SLL_ values below. If you must change the link-layer header
* for a "cooked" Linux capture, introduce a new DLT_ type (ask
* "tcpdump-workers@lists.tcpdump.org" for one, so that you don't give it
* a value that collides with a value already being used), and use the
* new header in captures of that type, so that programs that can
* handle DLT_LINUX_SLL captures will continue to handle them correctly
* without any change, and so that capture files with different headers
* can be told apart and programs that read them can dissect the
* packets in them.
*
* This structure, and the #defines below, must be the same in the
* libpcap and tcpdump versions of "sll.h".
*/
/*
* A DLT_LINUX_SLL fake link-layer header.
*/
#define SLL_HDR_LEN 16 /* total header length */
#define SLL_ADDRLEN 8 /* length of address field */
struct sll_header {
uint16_t sll_pkttype; /* packet type */
uint16_t sll_hatype; /* link-layer address type */
uint16_t sll_halen; /* link-layer address length */
uint8_t sll_addr[SLL_ADDRLEN]; /* link-layer address */
uint16_t sll_protocol; /* protocol */
};
/*
* The LINUX_SLL_ values for "sll_pkttype"; these correspond to the
* PACKET_ values on Linux, but are defined here so that they're
* available even on systems other than Linux, and so that they
* don't change even if the PACKET_ values change.
*/
#define LINUX_SLL_HOST 0
#define LINUX_SLL_BROADCAST 1
#define LINUX_SLL_MULTICAST 2
#define LINUX_SLL_OTHERHOST 3
#define LINUX_SLL_OUTGOING 4
/*
* The LINUX_SLL_ values for "sll_protocol"; these correspond to the
* ETH_P_ values on Linux, but are defined here so that they're
* available even on systems other than Linux. We assume, for now,
* that the ETH_P_ values won't change in Linux; if they do, then:
*
* if we don't translate them in "pcap-linux.c", capture files
* won't necessarily be readable if captured on a system that
* defines ETH_P_ values that don't match these values;
*
* if we do translate them in "pcap-linux.c", that makes life
* unpleasant for the BPF code generator, as the values you test
* for in the kernel aren't the values that you test for when
* reading a capture file, so the fixup code run on BPF programs
* handed to the kernel ends up having to do more work.
*
* Add other values here as necessary, for handling packet types that
* might show up on non-Ethernet, non-802.x networks. (Not all the ones
* in the Linux "if_ether.h" will, I suspect, actually show up in
* captures.)
*/
#define LINUX_SLL_P_802_3 0x0001 /* Novell 802.3 frames without 802.2 LLC header */
#define LINUX_SLL_P_802_2 0x0004 /* 802.2 frames (not D/I/X Ethernet) */
static const struct tok sll_pkttype_values[] = {
{ LINUX_SLL_HOST, "In" },
{ LINUX_SLL_BROADCAST, "B" },
{ LINUX_SLL_MULTICAST, "M" },
{ LINUX_SLL_OTHERHOST, "P" },
{ LINUX_SLL_OUTGOING, "Out" },
{ 0, NULL}
};
static inline void
sll_print(netdissect_options *ndo, register const struct sll_header *sllp, u_int length)
{
u_short ether_type;
ND_PRINT((ndo, "%3s ",tok2str(sll_pkttype_values,"?",EXTRACT_16BITS(&sllp->sll_pkttype))));
/*
* XXX - check the link-layer address type value?
* For now, we just assume 6 means Ethernet.
* XXX - print others as strings of hex?
*/
if (EXTRACT_16BITS(&sllp->sll_halen) == 6)
ND_PRINT((ndo, "%s ", etheraddr_string(ndo, sllp->sll_addr)));
if (!ndo->ndo_qflag) {
ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
if (ether_type <= ETHERMTU) {
/*
* Not an Ethernet type; what type is it?
*/
switch (ether_type) {
case LINUX_SLL_P_802_3:
/*
* Ethernet_802.3 IPX frame.
*/
ND_PRINT((ndo, "802.3"));
break;
case LINUX_SLL_P_802_2:
/*
* 802.2.
*/
ND_PRINT((ndo, "802.2"));
break;
default:
/*
* What is it?
*/
ND_PRINT((ndo, "ethertype Unknown (0x%04x)",
ether_type));
break;
}
} else {
ND_PRINT((ndo, "ethertype %s (0x%04x)",
tok2str(ethertype_values, "Unknown", ether_type),
ether_type));
}
ND_PRINT((ndo, ", length %u: ", length));
}
}
/*
* This is the top level routine of the printer. 'p' points to the
* Linux "cooked capture" header of the packet, 'h->ts' is the timestamp,
* 'h->len' is the length of the packet off the wire, and 'h->caplen'
* is the number of bytes actually captured.
*/
u_int
sll_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
{
u_int caplen = h->caplen;
u_int length = h->len;
register const struct sll_header *sllp;
u_short ether_type;
u_short extracted_ethertype;
if (caplen < SLL_HDR_LEN) {
/*
* XXX - this "can't happen" because "pcap-linux.c" always
* adds this many bytes of header to every packet in a
* cooked socket capture.
*/
ND_PRINT((ndo, "[|sll]"));
return (caplen);
}
sllp = (const struct sll_header *)p;
if (ndo->ndo_eflag)
sll_print(ndo, sllp, length);
/*
* Go past the cooked-mode header.
*/
length -= SLL_HDR_LEN;
caplen -= SLL_HDR_LEN;
p += SLL_HDR_LEN;
ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
recurse:
/*
* Is it (gag) an 802.3 encapsulation, or some non-Ethernet
* packet type?
*/
if (ether_type <= ETHERMTU) {
/*
* Yes - what type is it?
*/
switch (ether_type) {
case LINUX_SLL_P_802_3:
/*
* Ethernet_802.3 IPX frame.
*/
ipx_print(ndo, p, length);
break;
case LINUX_SLL_P_802_2:
/*
* 802.2.
* Try to print the LLC-layer header & higher layers.
*/
if (llc_print(ndo, p, length, caplen, NULL, NULL,
&extracted_ethertype) == 0)
goto unknown; /* unknown LLC type */
break;
default:
extracted_ethertype = 0;
/*FALLTHROUGH*/
unknown:
/* ether_type not known, print raw packet */
if (!ndo->ndo_eflag)
sll_print(ndo, sllp, length + SLL_HDR_LEN);
if (extracted_ethertype) {
ND_PRINT((ndo, "(LLC %s) ",
etherproto_string(htons(extracted_ethertype))));
}
if (!ndo->ndo_suppress_default_print)
ND_DEFAULTPRINT(p, caplen);
break;
}
} else if (ether_type == ETHERTYPE_8021Q) {
/*
* Print VLAN information, and then go back and process
* the enclosed type field.
*/
if (caplen < 4 || length < 4) {
ND_PRINT((ndo, "[|vlan]"));
return (SLL_HDR_LEN);
}
if (ndo->ndo_eflag) {
uint16_t tag = EXTRACT_16BITS(p);
ND_PRINT((ndo, "%s, ", ieee8021q_tci_string(tag)));
}
ether_type = EXTRACT_16BITS(p + 2);
if (ether_type <= ETHERMTU)
ether_type = LINUX_SLL_P_802_2;
if (!ndo->ndo_qflag) {
ND_PRINT((ndo, "ethertype %s, ",
tok2str(ethertype_values, "Unknown", ether_type)));
}
p += 4;
length -= 4;
caplen -= 4;
goto recurse;
} else {
if (ethertype_print(ndo, ether_type, p, length, caplen) == 0) {
/* ether_type not known, print raw packet */
if (!ndo->ndo_eflag)
sll_print(ndo, sllp, length + SLL_HDR_LEN);
if (!ndo->ndo_suppress_default_print)
ND_DEFAULTPRINT(p, caplen);
}
}
return (SLL_HDR_LEN);
}