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/*
* packet-pktap.c
* Routines for dissecting Apple's PKTAP header
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 2007 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/capture_dissectors.h>
#include <epan/expert.h>
#include <wsutil/pint.h>
#include "packet-eth.h"
static dissector_handle_t pcap_pktdata_handle;
void proto_register_pktap(void);
void proto_reg_handoff_pktap(void);
/*
* Apple's PKTAP header.
*/
/*
* Minimum header length.
*
* XXX - I'm assuming the header begins with a length field so that it
* can be transparently *extended*, not so that fields in the current
* header can be *omitted*.
*/
#define MIN_PKTAP_HDR_LEN 108
/*
* Record types.
*/
#define PKT_REC_NONE 0 /* nothing follows the header */
#define PKT_REC_PACKET 1 /* a packet follows the header */
/* Protocol */
static int proto_pktap;
static int hf_pktap_hdrlen;
static int hf_pktap_rectype;
static int hf_pktap_dlt;
static int hf_pktap_ifname;
static int hf_pktap_flags;
static int hf_pktap_pfamily;
static int hf_pktap_llhdrlen;
static int hf_pktap_lltrlrlen;
static int hf_pktap_pid;
static int hf_pktap_cmdname;
static int hf_pktap_svc_class;
static int hf_pktap_iftype;
static int hf_pktap_ifunit;
static int hf_pktap_epid;
static int hf_pktap_ecmdname;
static int ett_pktap;
static expert_field ei_pktap_hdrlen_too_short;
static dissector_handle_t pktap_handle;
static capture_dissector_handle_t eth_cap_handle;
/*
* XXX - these are only little-endian because they've been created on
* little-endian machines; the code in bsd/net/pktap.c in XNU writes
* the structure out in host byte order.
*
* We haven't been treating it as host-endian in libpcap and libwiretap,
* i.e. we haven't been byte-swapping its members when reading it on
* a machine whose byte order differs from the byte order of the machine
* on which the file is being read.
*
* Furthermore, the header is extensible, so we don't necessarily know
* what fields to swap.
*
* Fortunately, the length of the PKTAP header is a 32-bit field and is
* *presumably* never going to be 65536 or greater, so if any of the upper
* 16 bits appear to be set, it means we're looking at it in the wrong
* byte order, and it's never going to be zero, so those bits *will* be
* set if it's >= 65536, so we can determine its byte order.
*
* We should do that here.
*/
static bool
capture_pktap(const unsigned char *pd, int offset _U_, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header _U_)
{
uint32_t hdrlen, rectype, dlt;
hdrlen = pletoh32(pd);
if (hdrlen < MIN_PKTAP_HDR_LEN || !BYTES_ARE_IN_FRAME(0, len, hdrlen))
return false;
rectype = pletoh32(pd+4);
if (rectype != PKT_REC_PACKET)
return false;
dlt = pletoh32(pd+4);
/* XXX - We should probably combine this with capture_info.c:capture_info_packet() */
switch (dlt) {
case 1: /* DLT_EN10MB */
return call_capture_dissector(eth_cap_handle, pd, hdrlen, len, cpinfo, pseudo_header);
}
return false;
}
static int
dissect_pktap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
proto_tree *pktap_tree = NULL;
proto_item *ti = NULL;
tvbuff_t *next_tvb;
int offset = 0;
uint32_t pkt_len, rectype, dlt;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "PKTAP");
col_clear(pinfo->cinfo, COL_INFO);
pkt_len = tvb_get_letohl(tvb, offset);
col_add_fstr(pinfo->cinfo, COL_INFO, "PKTAP, %u byte header", pkt_len);
/* Dissect the packet */
ti = proto_tree_add_item(tree, proto_pktap, tvb, offset, pkt_len, ENC_NA);
pktap_tree = proto_item_add_subtree(ti, ett_pktap);
proto_tree_add_item(pktap_tree, hf_pktap_hdrlen, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
if (pkt_len < MIN_PKTAP_HDR_LEN) {
proto_tree_add_expert(tree, pinfo, &ei_pktap_hdrlen_too_short,
tvb, offset, 4);
return tvb_captured_length(tvb);
}
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_rectype, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
rectype = tvb_get_letohl(tvb, offset);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_dlt, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
dlt = tvb_get_letohl(tvb, offset);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_ifname, tvb, offset, 24,
ENC_ASCII);
offset += 24;
proto_tree_add_item(pktap_tree, hf_pktap_flags, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_pfamily, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_llhdrlen, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_lltrlrlen, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_pid, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_cmdname, tvb, offset, 20,
ENC_UTF_8);
offset += 20;
proto_tree_add_item(pktap_tree, hf_pktap_svc_class, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_iftype, tvb, offset, 2,
ENC_LITTLE_ENDIAN);
offset += 2;
proto_tree_add_item(pktap_tree, hf_pktap_ifunit, tvb, offset, 2,
ENC_LITTLE_ENDIAN);
offset += 2;
proto_tree_add_item(pktap_tree, hf_pktap_epid, tvb, offset, 4,
ENC_LITTLE_ENDIAN);
offset += 4;
proto_tree_add_item(pktap_tree, hf_pktap_ecmdname, tvb, offset, 20,
ENC_UTF_8);
/*offset += 20;*/
if (rectype == PKT_REC_PACKET) {
next_tvb = tvb_new_subset_remaining(tvb, pkt_len);
call_dissector_with_data(pcap_pktdata_handle, next_tvb,
pinfo, tree, &dlt);
}
return tvb_captured_length(tvb);
}
void
proto_register_pktap(void)
{
static hf_register_info hf[] = {
{ &hf_pktap_hdrlen,
{ "Header length", "pktap.hdrlen",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_rectype,
{ "Record type", "pktap.rectype",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_dlt,
{ "DLT", "pktap.dlt",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_ifname, /* fixed length *and* null-terminated */
{ "Interface name", "pktap.ifname",
FT_STRINGZ, BASE_NONE, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_flags,
{ "Flags", "pktap.flags",
FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_pfamily,
{ "Protocol family", "pktap.pfamily",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_llhdrlen,
{ "Link-layer header length", "pktap.llhdrlen",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_lltrlrlen,
{ "Link-layer trailer length", "pktap.lltrlrlen",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_pid,
{ "Process ID", "pktap.pid",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_cmdname, /* fixed length *and* null-terminated */
{ "Command name", "pktap.cmdname",
FT_STRINGZ, BASE_NONE, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_svc_class,
{ "Service class", "pktap.svc_class",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_iftype,
{ "Interface type", "pktap.iftype",
FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_ifunit,
{ "Interface unit", "pktap.ifunit",
FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_epid,
{ "Effective process ID", "pktap.epid",
FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } },
{ &hf_pktap_ecmdname, /* fixed length *and* null-terminated */
{ "Effective command name", "pktap.ecmdname",
FT_STRINGZ, BASE_NONE, NULL, 0x0, NULL, HFILL } },
};
static int *ett[] = {
&ett_pktap,
};
static ei_register_info ei[] = {
{ &ei_pktap_hdrlen_too_short,
{ "pktap.hdrlen_too_short", PI_MALFORMED, PI_ERROR,
"Header length is too short", EXPFILL }},
};
expert_module_t* expert_pktap;
proto_pktap = proto_register_protocol("PKTAP packet header", "PKTAP",
"pktap");
proto_register_field_array(proto_pktap, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_pktap = expert_register_protocol(proto_pktap);
expert_register_field_array(expert_pktap, ei, array_length(ei));
pktap_handle = register_dissector("pktap", dissect_pktap, proto_pktap);
}
void
proto_reg_handoff_pktap(void)
{
capture_dissector_handle_t pktap_cap_handle;
dissector_add_uint("wtap_encap", WTAP_ENCAP_PKTAP, pktap_handle);
pcap_pktdata_handle = find_dissector_add_dependency("pcap_pktdata", proto_pktap);
/* XXX - WTAP_ENCAP_USER2 to handle Mavericks' botch wherein it
uses DLT_USER2 for PKTAP; if you are using DLT_USER2 for your
own purposes, feel free to call your own capture_ routine for
WTAP_ENCAP_USER2. */
pktap_cap_handle = create_capture_dissector_handle(capture_pktap, proto_pktap);
capture_dissector_add_uint("wtap_encap", WTAP_ENCAP_PKTAP, pktap_cap_handle);
capture_dissector_add_uint("wtap_encap", WTAP_ENCAP_USER2, pktap_cap_handle);
eth_cap_handle = find_capture_dissector("eth");
}
/*
* 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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