Add a partial decoder for PCAP

1 files changed, 178 insertions, 0 deletions

diff --git a/plugins/pcap.lua b/plugins/pcap.lua
new file mode 100644
index 0000000..1b8d791
--- /dev/null
+++ b/plugins/pcap.lua
@@ -0,0 +1,178 @@
+--
+-- pcap.lua: libpcap file format
+--
+-- Copyright (c) 2017, Přemysl Janouch <p.janouch@gmail.com>
+--
+-- Permission to use, copy, modify, and/or distribute this software for any
+-- purpose with or without fee is hereby granted, provided that the above
+-- copyright notice and this permission notice appear in all copies.
+--
+-- 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)
+	local magic = c:read (4)
+	return magic == "\xa1\xb2\xc3\xd4" or magic == "\xd4\xc3\xb2\xa1"
+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:i32 ("UTC to local TZ correction: %d seconds")
+	local sigfigs = c:u32 ("timestamp accuracy")
+	local snaplen = c:u32 ("max. length of captured packets")
+
+	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 + 23):mark ("PCAP record %d header", i)
+		i = i + 1
+
+		local p, ts_sec, ts_usec = p, c:u32 (), c:u32 ()
+		c (p, c.position - 1):mark ("timestamp: %s.%06d",
+			os.date ("!%F %T", ts_sec + zonen), ts_usec)
+		local incl_len = c:u32 ("included record length")
+		local orig_len = c:u32 ("original record length")
+
+		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)
+	end
+end
+
+hex.register { type="pcap", detect=detect, decode=decode }
+