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--
-- pcap.lua: libpcap file format
--
-- Copyright (c) 2017, Přemysl Eric Janouch <p@janouch.name>
--
-- Permission to use, copy, modify, and/or distribute this software for any
-- purpose with or without fee is hereby granted.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
-- SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
-- OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
-- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
--
local detect = function (c)
if #c < 4 then
return false
end
local magic = c:u32 ()
return magic == 0xa1b2c3d4 or magic == 0xd4c3b2a1
end
local detect_ng = function (c)
if #c < 8 then
return false
end
local magic = c (9):u32 ()
return c:u32 () == 0x0a0d0d0a
and (magic == 0x1a2b3c4d or magic == 0x4d3c2b1a)
end
-- Specified in http://www.tcpdump.org/linktypes.html
local link_types = {
[0] = "NULL",
[1] = "ETHERNET",
[3] = "AX25",
[6] = "IEEE802_5",
[7] = "ARCNET_BSD",
[8] = "SLIP",
[9] = "PPP",
[10] = "FDDI",
[50] = "PPP_HDLC",
[51] = "PPP_ETHER",
[100] = "ATM_RFC1483",
[101] = "RAW",
[104] = "C_HDLC",
[105] = "IEEE802_11",
[107] = "FRELAY",
[108] = "LOOP",
[113] = "LINUX_SLL",
[114] = "LTALK",
[117] = "PFLOG",
[119] = "IEEE802_11_PRISM",
[122] = "IP_OVER_FC",
[123] = "SUNATM",
[127] = "IEEE802_11_RADIOTAP",
[129] = "ARCNET_LINUX",
[138] = "APPLE_IP_OVER_IEEE1394",
[139] = "MTP2_WITH_PHDR",
[140] = "MTP2",
[141] = "MTP3",
[142] = "SCCP",
[143] = "DOCSIS",
[144] = "LINUX_IRDA",
[147] = "USER0",
[148] = "USER1",
[149] = "USER2",
[150] = "USER3",
[151] = "USER4",
[152] = "USER5",
[153] = "USER6",
[154] = "USER7",
[155] = "USER8",
[156] = "USER9",
[157] = "USER10",
[158] = "USER11",
[159] = "USER12",
[160] = "USER13",
[161] = "USER14",
[162] = "USER15",
[163] = "IEEE802_11_AVS",
[165] = "BACNET_MS_TP",
[166] = "PPP_PPPD",
[169] = "GPRS_LLC",
[170] = "GPF_T",
[171] = "GPF_F",
[177] = "LINUX_LAPD",
[187] = "BLUETOOTH_HCI_H4",
[189] = "USB_LINUX",
[192] = "PPI",
[195] = "IEEE802_15_4",
[196] = "SITA",
[197] = "ERF",
[201] = "BLUETOOTH_HCI_H4_WITH_PHDR",
[202] = "AX25_KISS",
[203] = "LAPD",
[204] = "PPP_WITH_DIR",
[205] = "C_HDLC_WITH_DIR",
[206] = "FRELAY_WITH_DIR",
[209] = "IPMB_LINUX",
[215] = "IEEE802_15_4_NONASK_PHY",
[220] = "USB_LINUX_MMAPPED",
[224] = "FC_2",
[225] = "FC_2_WITH_FRAME_DELIMS",
[226] = "IPNET",
[227] = "CAN_SOCKETCAN",
[228] = "IPV4",
[229] = "IPV6",
[230] = "IEEE802_15_4_NOFCS",
[231] = "DBUS",
[235] = "DVB_CI",
[236] = "MUX27010",
[237] = "STANAG_5066_D_PDU",
[239] = "NFLOG",
[240] = "NETANALYZER",
[241] = "NETANALYZER_TRANSPARENT",
[242] = "IPOIB",
[243] = "MPEG_2_TS",
[244] = "NG40",
[245] = "NFC_LLCP",
[247] = "INFINIBAND",
[248] = "SCTP",
[249] = "USBPCAP",
[250] = "RTAC_SERIAL",
[251] = "BLUETOOTH_LE_LL",
[253] = "NETLINK",
[254] = "BLUETOOTH_LINUX_MONITOR",
[255] = "BLUETOOTH_BREDR_BB",
[256] = "BLUETOOTH_LE_LL_WITH_PHDR",
[257] = "PROFIBUS_DL",
[258] = "PKTAP",
[259] = "EPON",
[260] = "IPMI_HPM_2",
[261] = "ZWAVE_R1_R2",
[262] = "ZWAVE_R3",
[263] = "WATTSTOPPER_DLM",
[264] = "ISO_14443",
[265] = "RDS",
[266] = "USB_DARWIN"
}
-- As described by https://wiki.wireshark.org/Development/LibpcapFileFormat
local decode = function (c)
if not detect (c ()) then error ("not a PCAP file") end
c.endianity = "le"
c:u32 ("PCAP magic: %s", function (u32)
if u32 == 0xa1b2c3d4 then return "little-endian" end
c.endianity = "be"
return "big-endian"
end)
local p, vmajor, vminor = c.position, c:u16 (), c:u16 ()
c (p, c.position - 1):mark ("PCAP version: %d.%d", vmajor, vminor)
local zone = c:s32 ("UTC to local TZ correction: %d seconds")
local sigfigs = c:u32 ("timestamp accuracy")
local snaplen = c:u32 ("max. length of captured packets: %d")
local network = c:u32 ("data link type: %s", function (u32)
name = link_types[u32]
if name then return name end
return "unknown: %d", u32
end)
local i = 0
while not c.eof do
c (c.position, c.position + 15):mark ("PCAP record %d header", i)
local p, ts_sec, ts_usec = c.position, c:u32 (), c:u32 ()
c (p, c.position - 1):mark ("timestamp: %s.%06d",
os.date ("!%F %T", ts_sec + zone), ts_usec)
local incl_len = c:u32 ("included record length: %d")
local orig_len = c:u32 ("original record length: %d")
local p = c.position
c.position = c.position + incl_len
-- TODO: also decode record contents as per the huge table
c (p, c.position - 1):mark ("PCAP record %d data", i)
i = i + 1
end
end
hex.register { type="pcap", detect=detect, decode=decode }
local block_types = {
[0x0a0d0d0a] = "Section Header Block",
[0x00000001] = "Interface Description Block",
[0x00000003] = "Simple Packet Block",
[0x00000004] = "Name Resolution Block",
[0x00000005] = "Interface Statistics Block",
[0x00000006] = "Enhanced Packet Block",
[0x00000BAD] = "Custom Block",
[0x40000BAD] = "Custom Block"
}
local decode_shb = function (c)
local magic = c:u32 ()
local p, vmajor, vminor = c.position, c:u16 (), c:u16 ()
c (p, c.position - 1):mark ("PCAPNG version: %d.%d", vmajor, vminor)
-- XXX: what exactly does section_len mean?
local section_len = c:u64 ("section length: %d")
while not c.eof do
-- TODO: decode the meaning of options as well
local type = c:u16 ("option type: %d")
local length = c:u16 ("option length: %d")
local p = c.position
c.position = c.position + length + (-length & 3)
c (p, c.position - 1):mark ("option value")
end
end
local block_decoders = {
-- TODO: also decode other types of blocks
[0x0a0d0d0a] = decode_shb
}
-- As described by https://github.com/pcapng/pcapng
local decode_ng = function (c)
assert (c.position == 1)
if not detect_ng (c ()) then error ("not a PCAPNG file") end
c.endianity = "le"
c (9):u32 ("byte-order magic: %s", function (u32)
if u32 == 0x1a2b3c4d then return "little-endian" end
c.endianity = "be"
return "big-endian"
end)
while not c.eof do
local block_start = c.position
local block_type = c:u32 ("PCAPNG block type: %s", function (u32)
local name = block_types[u32]
if name then return name end
return "unknown: %d", u32
end)
local block_len = c:u32 ("PCAPNG block length: %d")
local data_start = c.position
c.position = block_start + block_len - 4
local decoder = block_decoders[block_type]
if decoder then decoder (c (data_start, c.position - 1)) end
c:u32 ("PCAPNG trailing block length: %d")
end
end
hex.register { type="pcapng", detect=detect_ng, decode=decode_ng }
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