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pcap.js
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pcap.js
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/*global process require exports console */
var util, IOWatcher,
dns = require('dns'),
Buffer = require('buffer').Buffer,
events = require('events'),
binding = require('./build/Release/pcap_binding'),
HTTPParser = process.binding('http_parser').HTTPParser,
url = require('url');
if (process.versions && process.versions.node && process.versions.node.split('.')[1] >= 3) {
util = require("util");
IOWatcher = process.binding('io_watcher').IOWatcher;
} else {
util = require('util');
IOWatcher = process.IOWatcher;
}
function Pcap() {
this.opened = false;
this.fd = null;
events.EventEmitter.call(this);
}
util.inherits(Pcap, events.EventEmitter);
exports.lib_version = binding.lib_version();
Pcap.prototype.findalldevs = function () {
return binding.findalldevs();
};
Pcap.prototype.open = function (live, device, filter, buffer_size, pcap_output_filename) {
var me = this;
if (typeof buffer_size === 'number' && !isNaN(buffer_size)) {
this.buffer_size = Math.round(buffer_size);
} else {
this.buffer_size = 10 * 1024 * 1024; // Default buffer size is 10MB
}
this.live = live;
if (live) {
this.device_name = device || binding.default_device();
this.link_type = binding.open_live(this.device_name, filter || "", this.buffer_size, pcap_output_filename || "");
} else {
this.device_name = device;
this.link_type = binding.open_offline(this.device_name, filter || "", this.buffer_size, pcap_output_filename || "");
}
this.fd = binding.fileno();
this.opened = true;
this.readWatcher = new IOWatcher();
this.empty_reads = 0;
this.buf = new Buffer(65535);
// called for each packet read by pcap
function packet_ready(header) {
header.link_type = me.link_type;
header.time_ms = (header.tv_sec * 1000) + (header.tv_usec / 1000);
me.buf.pcap_header = header;
me.emit('packet', me.buf);
}
// readWatcher gets a callback when pcap has data to read. multiple packets may be readable.
this.readWatcher.callback = function pcap_read_callback() {
var packets_read = binding.dispatch(me.buf, packet_ready);
if (packets_read < 1) {
// according to pcap_dispatch documentation if 0 is returned when reading
// from a savefile there will be no more packets left. this check ensures
// we stop reading. Under certain circumstances IOWatcher will get caught
// in a loop and continue to signal us causing the program to be flooded
// with events.
if(!me.live) {
me.readWatcher.stop();
me.emit('complete');
}
// TODO - figure out what is causing this, and if it is bad.
me.empty_reads += 1;
}
};
this.readWatcher.set(this.fd, true, false);
this.readWatcher.start();
};
Pcap.prototype.close = function () {
this.opened = false;
binding.close();
// TODO - remove listeners so program will exit I guess?
};
Pcap.prototype.stats = function () {
return binding.stats();
};
exports.Pcap = Pcap;
exports.createSession = function (device, filter, buffer_size) {
var session = new Pcap();
session.open(true, device, filter, buffer_size);
return session;
};
exports.createOfflineSession = function (path, filter) {
var session = new Pcap();
session.open(false, path, filter, 0);
return session;
};
//
// Decoding functions
//
function lpad(str, len) {
while (str.length < len) {
str = "0" + str;
}
return str;
}
function dump_bytes(raw_packet, offset) {
for (var i = offset; i < raw_packet.pcap_header.caplen ; i += 1) {
console.log(i + ": " + raw_packet[i]);
}
}
var unpack = {
ethernet_addr: function (raw_packet, offset) {
return [
lpad(raw_packet[offset].toString(16), 2),
lpad(raw_packet[offset + 1].toString(16), 2),
lpad(raw_packet[offset + 2].toString(16), 2),
lpad(raw_packet[offset + 3].toString(16), 2),
lpad(raw_packet[offset + 4].toString(16), 2),
lpad(raw_packet[offset + 5].toString(16), 2)
].join(":");
},
uint16: function (raw_packet, offset) {
return ((raw_packet[offset] * 256) + raw_packet[offset + 1]);
},
uint16_be: function (raw_packet, offset) {
return ((raw_packet[offset+1] * 256) + raw_packet[offset]);
},
uint32: function (raw_packet, offset) {
return (
(raw_packet[offset] * 16777216) +
(raw_packet[offset + 1] * 65536) +
(raw_packet[offset + 2] * 256) +
raw_packet[offset + 3]
);
},
uint64: function (raw_packet, offset) {
return (
(raw_packet[offset] * 72057594037927936) +
(raw_packet[offset + 1] * 281474976710656) +
(raw_packet[offset + 2] * 1099511627776) +
(raw_packet[offset + 3] * 4294967296) +
(raw_packet[offset + 4] * 16777216) +
(raw_packet[offset + 5] * 65536) +
(raw_packet[offset + 6] * 256) +
raw_packet[offset + 7]
);
},
ipv4_addr: function (raw_packet, offset) {
return [
raw_packet[offset],
raw_packet[offset + 1],
raw_packet[offset + 2],
raw_packet[offset + 3]
].join('.');
},
ipv6_addr: function (raw_packet, offset) {
var ret = '';
var octets = [];
for (var i=offset; i<offset+16; i+=2) {
octets.push(unpack.uint16(raw_packet,i).toString(16));
}
var curr_start, curr_len = undefined;
var max_start, max_len = undefined;
for(var i = 0; i < 8; i++){
if(octets[i] == "0"){
if(curr_start === undefined){
curr_len = 1;
curr_start = i;
}else{
curr_len++;
if(!max_start || curr_len > max_len){
max_start = curr_start;
max_len = curr_len;
}
}
}else{
curr_start = undefined;
}
}
if(max_start !== undefined){
var tosplice = max_start == 0 || (max_start + max_len > 7) ? ":" : "";
octets.splice(max_start, max_len,tosplice);
if(max_len == 8){octets.push("");}
}
ret = octets.join(":");
return ret;
}
};
exports.unpack = unpack;
var decode = {}; // convert raw packet data into JavaScript objects with friendly names
decode.packet = function (raw_packet) {
var packet = {};
packet.link_type = raw_packet.pcap_header.link_type;
switch (packet.link_type) {
case "LINKTYPE_ETHERNET":
packet.link = decode.ethernet(raw_packet, 0);
break;
case "LINKTYPE_NULL":
packet.link = decode.nulltype(raw_packet, 0);
break;
case "LINKTYPE_RAW":
packet.link = decode.rawtype(raw_packet, 0);
break;
case "LINKTYPE_IEEE802_11_RADIO":
packet.link = decode.ieee802_11_radio(raw_packet, 0);
break;
default:
console.log("pcap.js: decode.packet() - Don't yet know how to decode link type " + raw_packet.pcap_header.link_type);
}
packet.pcap_header = raw_packet.pcap_header; // TODO - merge values here instead of putting ref on packet buffer
return packet;
};
decode.rawtype = function (raw_packet, offset) {
var ret = {};
ret.ip = decode.ip(raw_packet, 0);
return ret;
};
decode.nulltype = function (raw_packet, offset) {
var ret = {};
// an oddity about nulltype is that it starts with a 4 byte header, but I can't find a
// way to tell which byte order is used. The good news is that all address family
// values are 8 bits or less.
if (raw_packet[0] === 0 && raw_packet[1] === 0) { // must be one of the endians
ret.pftype = raw_packet[3];
} else { // and this is the other one
ret.pftype = raw_packet[0];
}
if (ret.pftype === 2) { // AF_INET, at least on my Linux and OSX machines right now
ret.ip = decode.ip(raw_packet, 4);
} else if (ret.pftype === 30) { // AF_INET6, often
ret.ip = decode.ip6(raw_packet, 4);
} else {
console.log("pcap.js: decode.nulltype() - Don't know how to decode protocol family " + ret.pftype);
}
return ret;
};
decode.ethernet = function (raw_packet, offset) {
var ret = {};
ret.dhost = unpack.ethernet_addr(raw_packet, 0);
ret.shost = unpack.ethernet_addr(raw_packet, 6);
ret.ethertype = unpack.uint16(raw_packet, 12);
offset = 14;
// Check for a tagged frame
switch (ret.ethertype) {
case 0x8100: // VLAN-tagged (802.1Q)
ret.vlan = decode.vlan(raw_packet, 14);
// Update the ethertype
ret.ethertype = unpack.uint16(raw_packet, 16);
offset = 18;
break;
}
if (ret.ethertype < 1536) {
// this packet is actually some 802.3 type without an ethertype
ret.ethertype = 0;
} else {
// http://en.wikipedia.org/wiki/EtherType
switch (ret.ethertype) {
case 0x800: // IPv4
ret.ip = decode.ip(raw_packet, offset);
break;
case 0x806: // ARP
ret.arp = decode.arp(raw_packet, offset);
break;
case 0x86dd: // IPv6 - http://en.wikipedia.org/wiki/IPv6
ret.ipv6 = decode.ip6(raw_packet, offset);
break;
case 0x88cc: // LLDP - http://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol
ret.lldp = "need to implement LLDP";
break;
default:
console.log("pcap.js: decode.ethernet() - Don't know how to decode ethertype " + ret.ethertype);
}
}
return ret;
};
decode.ieee802_11_radio = function (raw_packet, offset) {
var ret = {};
var original_offset = offset;
ret.headerRevision = raw_packet[offset++];
ret.headerPad = raw_packet[offset++];
ret.headerLength = unpack.uint16_be(raw_packet, offset); offset += 2;
offset = original_offset + ret.headerLength;
ret.ieee802_11Frame = decode.ieee802_11_frame(raw_packet, offset);
if(ret.ieee802_11Frame && ret.ieee802_11Frame.llc && ret.ieee802_11Frame.llc.ip) {
ret.ip = ret.ieee802_11Frame.llc.ip;
delete ret.ieee802_11Frame.llc.ip;
ret.shost = ret.ieee802_11Frame.shost;
delete ret.ieee802_11Frame.shost;
ret.dhost = ret.ieee802_11Frame.dhost;
delete ret.ieee802_11Frame.dhost
}
return ret;
};
decode.ieee802_11_frame = function (raw_packet, offset) {
var ret = {};
ret.frameControl = unpack.uint16_be(raw_packet, offset); offset += 2;
ret.type = (ret.frameControl >> 2) & 0x0003;
ret.subType = (ret.frameControl >> 4) & 0x000f;
ret.flags = (ret.frameControl >> 8) & 0xff;
ret.duration = unpack.uint16_be(raw_packet, offset); offset += 2;
ret.bssid = unpack.ethernet_addr(raw_packet, offset); offset += 6;
ret.shost = unpack.ethernet_addr(raw_packet, offset); offset += 6;
ret.dhost = unpack.ethernet_addr(raw_packet, offset); offset += 6;
ret.fragSeq = unpack.uint16_be(raw_packet, offset); offset += 2;
switch(ret.subType) {
case 8: // QoS Data
ret.qosPriority = raw_packet[offset++];
ret.txop = raw_packet[offset++];
break;
}
if(ret.type == 2 && ret.subType == 4) {
// skip this is Null function (No data)
}
else if(ret.type == 2 && ret.subType == 12) {
// skip this is QoS Null function (No data)
}
else if(ret.type == 2 && ret.subType == 7) {
// skip this is CF-Ack/Poll
}
else if(ret.type == 2 && ret.subType == 6) {
// skip this is CF-Poll (No data)
}
else if(ret.type == 2) { // data
ret.llc = decode.logicalLinkControl(raw_packet, offset);
}
return ret;
};
decode.logicalLinkControl = function (raw_packet, offset) {
var ret = {};
ret.dsap = raw_packet[offset++];
ret.ssap = raw_packet[offset++];
if(((ret.dsap == 0xaa) && (ret.ssap == 0xaa))
|| ((ret.dsap == 0x00) && (ret.ssap == 0x00))) {
ret.controlField = raw_packet[offset++];
ret.orgCode = [
raw_packet[offset++],
raw_packet[offset++],
raw_packet[offset++]
];
ret.type = unpack.uint16(raw_packet, offset); offset += 2;
switch(ret.type) {
case 0x0800: // ip
ret.ip = decode.ip(raw_packet, offset);
break;
}
} else {
throw new Error("Unknown LLC types: DSAP: " + ret.dsap + ", SSAP: " + ret.ssap);
}
return ret;
}
decode.vlan = function (raw_packet, offset) {
var ret = {};
// http://en.wikipedia.org/wiki/IEEE_802.1Q
ret.priority = (raw_packet[offset] & 0xE0) >> 5;
ret.canonical_format = (raw_packet[offset] & 0x10) >> 4;
ret.id = ((raw_packet[offset] & 0x0F) << 8) | raw_packet[offset + 1];
return ret;
};
decode.arp = function (raw_packet, offset) {
var ret = {};
// http://en.wikipedia.org/wiki/Address_Resolution_Protocol
ret.htype = unpack.uint16(raw_packet, offset); // 0, 1
ret.ptype = unpack.uint16(raw_packet, offset + 2); // 2, 3
ret.hlen = raw_packet[offset + 4];
ret.plen = raw_packet[offset + 5];
ret.operation = unpack.uint16(raw_packet, offset + 6); // 6, 7
if (ret.operation === 1) {
ret.operation = "request";
}
else if (ret.operation === 2) {
ret.operation = "reply";
}
else {
ret.operation = "unknown";
}
if (ret.hlen === 6 && ret.plen === 4) { // ethernet + IPv4
ret.sender_ha = unpack.ethernet_addr(raw_packet, offset + 8); // 8, 9, 10, 11, 12, 13
ret.sender_pa = unpack.ipv4_addr(raw_packet, offset + 14); // 14, 15, 16, 17
ret.target_ha = unpack.ethernet_addr(raw_packet, offset + 18); // 18, 19, 20, 21, 22, 23
ret.target_pa = unpack.ipv4_addr(raw_packet, offset + 24); // 24, 25, 26, 27
}
// don't know how to decode more exotic ARP types
return ret;
};
decode.ip = function (raw_packet, offset) {
var ret = {};
// http://en.wikipedia.org/wiki/IPv4
ret.version = (raw_packet[offset] & 240) >> 4; // first 4 bits
ret.header_length = raw_packet[offset] & 15; // second 4 bits
ret.header_bytes = ret.header_length * 4;
ret.diffserv = raw_packet[offset + 1];
ret.total_length = unpack.uint16(raw_packet, offset + 2); // 2, 3
ret.identification = unpack.uint16(raw_packet, offset + 4); // 4, 5
ret.flags = {};
ret.flags.reserved = (raw_packet[offset + 6] & 128) >> 7;
ret.flags.df = (raw_packet[offset + 6] & 64) >> 6;
ret.flags.mf = (raw_packet[offset + 6] & 32) >> 5;
ret.fragment_offset = ((raw_packet[offset + 6] & 31) * 256) + raw_packet[offset + 7]; // 13-bits from 6, 7
ret.ttl = raw_packet[offset + 8];
ret.protocol = raw_packet[offset + 9];
ret.header_checksum = unpack.uint16(raw_packet, offset + 10); // 10, 11
ret.saddr = unpack.ipv4_addr(raw_packet, offset + 12); // 12, 13, 14, 15
ret.daddr = unpack.ipv4_addr(raw_packet, offset + 16); // 16, 17, 18, 19
// TODO - parse IP "options" if header_length > 5
switch (ret.protocol) {
case 1:
ret.protocol_name = "ICMP";
ret.icmp = decode.icmp(raw_packet, offset + (ret.header_length * 4));
break;
case 2:
ret.protocol_name = "IGMP";
ret.igmp = decode.igmp(raw_packet, offset + (ret.header_length * 4));
break;
case 6:
ret.protocol_name = "TCP";
ret.tcp = decode.tcp(raw_packet, offset + (ret.header_length * 4), ret);
break;
case 17:
ret.protocol_name = "UDP";
ret.udp = decode.udp(raw_packet, offset + (ret.header_length * 4));
break;
default:
ret.protocol_name = "Unknown";
}
return ret;
};
decode.ip6_header = function(raw_packet, next_header, ip, offset) {
switch (next_header) {
case 1:
ip.protocol_name = "ICMP";
ip.icmp = decode.icmp(raw_packet, offset);
break;
case 2:
ip.protocol_name = "IGMP";
ip.igmp = decode.igmp(raw_packet, offset);
break;
case 6:
ip.protocol_name = "TCP";
ip.tcp = decode.tcp(raw_packet, offset, ip);
break;
case 17:
ip.protocol_name = "UDP";
ip.udp = decode.udp(raw_packet, offset);
break;
default:
// TODO: capture the extensions
//decode.ip6_header(raw_packet, raw_packet[offset], offset + raw_packet[offset+1]);
}
};
decode.ip6 = function (raw_packet, offset) {
var ret = {};
// http://en.wikipedia.org/wiki/IPv6
ret.version = (raw_packet[offset] & 240) >> 4; // first 4 bits
ret.traffic_class = ((raw_packet[offset] & 15) << 4) + ((raw_packet[offset+1] & 240) >> 4);
ret.flow_label = ((raw_packet[offset + 1] & 15) << 16) +
(raw_packet[offset + 2] << 8) +
raw_packet[offset + 3];
ret.payload_length = unpack.uint16(raw_packet, offset+4);
ret.total_length = ret.payload_length + 40;
ret.next_header = raw_packet[offset+6];
ret.hop_limit = raw_packet[offset+7];
ret.saddr = unpack.ipv6_addr(raw_packet, offset+8);
ret.daddr = unpack.ipv6_addr(raw_packet, offset+24);
ret.header_bytes = 40;
decode.ip6_header(raw_packet, ret.next_header, ret, offset+40);
return ret;
};
decode.icmp = function (raw_packet, offset) {
var ret = {};
// http://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
ret.type = raw_packet[offset];
ret.code = raw_packet[offset + 1];
ret.checksum = unpack.uint16(raw_packet, offset + 2); // 2, 3
ret.id = unpack.uint16(raw_packet, offset + 4); // 4, 5
ret.sequence = unpack.uint16(raw_packet, offset + 6); // 6, 7
switch (ret.type) {
case 0:
ret.type_desc = "Echo Reply";
break;
case 1:
case 2:
ret.type_desc = "Reserved";
break;
case 3:
switch (ret.code) {
case 0:
ret.type_desc = "Destination Network Unreachable";
break;
case 1:
ret.type_desc = "Destination Host Unreachable";
break;
case 2:
ret.type_desc = "Destination Protocol Unreachable";
break;
case 3:
ret.type_desc = "Destination Port Unreachable";
break;
case 4:
ret.type_desc = "Fragmentation required, and DF flag set";
break;
case 5:
ret.type_desc = "Source route failed";
break;
case 6:
ret.type_desc = "Destination network unknown";
break;
case 7:
ret.type_desc = "Destination host unknown";
break;
case 8:
ret.type_desc = "Source host isolated";
break;
case 9:
ret.type_desc = "Network administratively prohibited";
break;
case 10:
ret.type_desc = "Host administratively prohibited";
break;
case 11:
ret.type_desc = "Network unreachable for TOS";
break;
case 12:
ret.type_desc = "Host unreachable for TOS";
break;
case 13:
ret.type_desc = "Communication administratively prohibited";
break;
default:
ret.type_desc = "Destination Unreachable (unknown code " + ret.code + ")";
}
break;
case 4:
ret.type_desc = "Source Quench";
break;
case 5:
switch (ret.code) {
case 0:
ret.type_desc = "Redirect Network";
break;
case 1:
ret.type_desc = "Redirect Host";
break;
case 2:
ret.type_desc = "Redirect TOS and Network";
break;
case 3:
ret.type_desc = "Redirect TOS and Host";
break;
default:
ret.type_desc = "Redirect (unknown code " + ret.code + ")";
break;
}
break;
case 6:
ret.type_desc = "Alternate Host Address";
break;
case 7:
ret.type_desc = "Reserved";
break;
case 8:
ret.type_desc = "Echo Request";
break;
case 9:
ret.type_desc = "Router Advertisement";
break;
case 10:
ret.type_desc = "Router Solicitation";
break;
case 11:
switch (ret.code) {
case 0:
ret.type_desc = "TTL expired in transit";
break;
case 1:
ret.type_desc = "Fragment reassembly time exceeded";
break;
default:
ret.type_desc = "Time Exceeded (unknown code " + ret.code + ")";
}
break;
// TODO - decode the rest of the well-known ICMP messages
default:
ret.type_desc = "type " + ret.type + " code " + ret.code;
}
// There are usually more exciting things hiding in ICMP packets after the headers
return ret;
};
decode.igmp = function (raw_packet, offset) {
var ret = {};
// http://en.wikipedia.org/wiki/Internet_Group_Management_Protocol
ret.type = raw_packet[offset];
ret.max_response_time = raw_packet[offset + 1];
ret.checksum = unpack.uint16(raw_packet, offset + 2); // 2, 3
ret.group_address = unpack.ipv4_addr(raw_packet, offset + 4); // 4, 5, 6, 7
switch (ret.type) {
case 0x11:
ret.version = ret.max_response_time > 0 ? 2 : 1;
ret.type_desc = "Membership Query"
break;
case 0x12:
ret.version = 1;
ret.type_desc = "Membership Report"
break;
case 0x16:
ret.version = 2;
ret.type_desc = "Membership Report"
break;
case 0x17:
ret.version = 2;
ret.type_desc = "Leave Group"
break;
case 0x22:
ret.version = 3;
ret.type_desc = "Membership Report"
// TODO: Decode v3 message
break;
default:
ret.type_desc = "type " + ret.type;
break;
}
return ret;
}
decode.udp = function (raw_packet, offset) {
var ret = {};
// http://en.wikipedia.org/wiki/User_Datagram_Protocol
ret.sport = unpack.uint16(raw_packet, offset); // 0, 1
ret.dport = unpack.uint16(raw_packet, offset + 2); // 2, 3
ret.length = unpack.uint16(raw_packet, offset + 4); // 4, 5
ret.checksum = unpack.uint16(raw_packet, offset + 6); // 6, 7
ret.data_offset = offset + 8;
ret.data_end = ret.length + ret.data_offset - 8;
ret.data_bytes = ret.data_end - ret.data_offset;
// Follow tcp pattern and don't make a copy of the data payload
// Therefore its only valid for this pass throught the capture loop
if (ret.data_bytes > 0) {
ret.data = raw_packet.slice(ret.data_offset, ret.data_end);
ret.data.length = ret.data_bytes;
}
if (ret.sport === 53 || ret.dport === 53) {
ret.dns = decode.dns(raw_packet, offset + 8);
}
return ret;
};
decode.tcp = function (raw_packet, offset, ip) {
var ret = {}, option_offset, options_end;
// http://en.wikipedia.org/wiki/Transmission_Control_Protocol
ret.sport = unpack.uint16(raw_packet, offset); // 0, 1
ret.dport = unpack.uint16(raw_packet, offset + 2); // 2, 3
ret.seqno = unpack.uint32(raw_packet, offset + 4); // 4, 5, 6, 7
ret.ackno = unpack.uint32(raw_packet, offset + 8); // 8, 9, 10, 11
ret.data_offset = (raw_packet[offset + 12] & 0xf0) >> 4; // first 4 bits of 12
ret.header_bytes = ret.data_offset * 4; // convenience for using data_offset
ret.reserved = raw_packet[offset + 12] & 15; // second 4 bits of 12
ret.flags = {};
ret.flags.cwr = (raw_packet[offset + 13] & 128) >> 7; // all flags packed into 13
ret.flags.ece = (raw_packet[offset + 13] & 64) >> 6;
ret.flags.urg = (raw_packet[offset + 13] & 32) >> 5;
ret.flags.ack = (raw_packet[offset + 13] & 16) >> 4;
ret.flags.psh = (raw_packet[offset + 13] & 8) >> 3;
ret.flags.rst = (raw_packet[offset + 13] & 4) >> 2;
ret.flags.syn = (raw_packet[offset + 13] & 2) >> 1;
ret.flags.fin = raw_packet[offset + 13] & 1;
ret.window_size = unpack.uint16(raw_packet, offset + 14); // 14, 15
ret.checksum = unpack.uint16(raw_packet, offset + 16); // 16, 17
ret.urgent_pointer = unpack.uint16(raw_packet, offset + 18); // 18, 19
ret.options = {};
option_offset = offset + 20;
options_end = offset + (ret.data_offset * 4);
while (option_offset < options_end) {
switch (raw_packet[option_offset]) {
case 0:
option_offset += 1;
break;
case 1:
option_offset += 1;
break;
case 2:
ret.options.mss = unpack.uint16(raw_packet, option_offset + 2);
option_offset += 4;
break;
case 3:
ret.options.window_scale = Math.pow(2, (raw_packet[option_offset + 2]));
option_offset += 3;
break;
case 4:
ret.options.sack_ok = true;
option_offset += 2;
break;
case 5:
ret.options.sack = [];
switch (raw_packet[option_offset + 1]) {
case 10:
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 2), unpack.uint32(raw_packet, option_offset + 6)]);
option_offset += 10;
break;
case 18:
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 2), unpack.uint32(raw_packet, option_offset + 6)]);
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 10), unpack.uint32(raw_packet, option_offset + 14)]);
option_offset += 18;
break;
case 26:
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 2), unpack.uint32(raw_packet, option_offset + 6)]);
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 10), unpack.uint32(raw_packet, option_offset + 14)]);
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 18), unpack.uint32(raw_packet, option_offset + 22)]);
option_offset += 26;
break;
case 34:
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 2), unpack.uint32(raw_packet, option_offset + 6)]);
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 10), unpack.uint32(raw_packet, option_offset + 14)]);
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 18), unpack.uint32(raw_packet, option_offset + 22)]);
ret.options.sack.push([unpack.uint32(raw_packet, option_offset + 26), unpack.uint32(raw_packet, option_offset + 30)]);
option_offset += 34;
break;
default:
console.log("Invalid TCP SACK option length " + raw_packet[option_offset + 1]);
option_offset = options_end;
}
break;
case 8:
ret.options.timestamp = unpack.uint32(raw_packet, option_offset + 2);
ret.options.echo = unpack.uint32(raw_packet, option_offset + 6);
option_offset += 10;
break;
default:
throw new Error("Don't know how to process TCP option " + raw_packet[option_offset]);
}
}
ret.data_offset = offset + ret.header_bytes;
ret.data_end = offset + ip.total_length - ip.header_bytes;
ret.data_bytes = ret.data_end - ret.data_offset;
if (ret.data_bytes > 0) {
// add a buffer slice pointing to the data area of this TCP packet.
// Note that this does not make a copy, so ret.data is only valid for this current
// trip through the capture loop.
ret.data = raw_packet.slice(ret.data_offset, ret.data_end);
ret.data.length = ret.data_bytes;
}
// automatic protocol decode ends here. Higher level protocols can be decoded by using payload.
return ret;
};
// helpers for DNS decoder
var dns_util = {
type_to_string: function (type_num) {
switch (type_num) {
case 1:
return "A";
case 2:
return "NS";
case 3:
return "MD";
case 4:
return "MF";
case 5:
return "CNAME";
case 6:
return "SOA";
case 7:
return "MB";
case 8:
return "MG";
case 9:
return "MR";
case 10:
return "NULL";
case 11:
return "WKS";
case 12:
return "PTR";
case 13:
return "HINFO";
case 14:
return "MINFO";
case 15:
return "MX";
case 16:
return "TXT";
default:
return ("Unknown (" + type_num + ")");
}
},
qtype_to_string: function (qtype_num) {
switch (qtype_num) {
case 252:
return "AXFR";
case 253:
return "MAILB";
case 254:
return "MAILA";
case 255:
return "*";
default:
return dns_util.type_to_string(qtype_num);
}
},
class_to_string: function (class_num) {
switch (class_num) {
case 1:
return "IN";
case 2:
return "CS";
case 3:
return "CH";
case 4:
return "HS";
default:
return "Unknown (" + class_num + ")";
}
},
qclass_to_string: function (qclass_num) {
if (qclass_num === 255) {
return "*";
} else {
return dns_util.class_to_string(qclass_num);
}
},
expandRRData: function(raw_packet, offset, rrRecord) {
if(rrRecord.rrtype == 'A' && rrRecord.rrclass == 'IN' && rrRecord.rdlength == 4) {
var data = {};
data.ipAddress = raw_packet[offset] + '.' + raw_packet[offset+1] + '.' + raw_packet[offset+2] + '.' + raw_packet[offset+3];
return data;
}
return null;
},
readName: function(raw_packet, offset, internal_offset, result) {
if(offset + internal_offset > raw_packet.pcap_header.len) {
throw new Error("Malformed DNS RR. Offset is larger than the size of the packet (readName).");
}
var lenOrPtr = raw_packet[offset + internal_offset];
internal_offset++;
if(lenOrPtr == 0x00) {
return result;
}
if((lenOrPtr & 0xC0) == 0xC0) {
var nameOffset = ((lenOrPtr & ~0xC0) << 8) | raw_packet[offset + internal_offset];
internal_offset++;
return dns_util.readName(raw_packet, offset, nameOffset, result);
}
for(var i=0; i<lenOrPtr; i++) {
var ch = raw_packet[offset + internal_offset];
internal_offset++;
result += String.fromCharCode(ch);
}
result += '.';
return dns_util.readName(raw_packet, offset, internal_offset, result);
},
decodeRR: function(raw_packet, offset, internal_offset, result) {
if(internal_offset > raw_packet.pcap_header.len) {
throw new Error("Malformed DNS RR. Offset is larger than the size of the packet (decodeRR). offset: " + offset + ", internal_offset: " + internal_offset + ", packet length: " + raw_packet.pcap_header.len);
}
var compressedName = raw_packet[internal_offset];
if((compressedName & 0xC0) == 0xC0) {
result.name = "";
result.name = dns_util.readName(raw_packet, offset, internal_offset - offset, result.name);
result.name = result.name.replace(/\.$/, '');
internal_offset += 2;
} else {
result.name = "";
var ch;
while((ch = raw_packet[internal_offset++]) != 0x00) {
result.name += String.fromCharCode(ch);
}
}
result.rrtype = dns_util.qtype_to_string(unpack.uint16(raw_packet, internal_offset));
internal_offset += 2;
result.rrclass = dns_util.qclass_to_string(unpack.uint16(raw_packet, internal_offset));
internal_offset += 2;
result.ttl = unpack.uint32(raw_packet, internal_offset);
internal_offset += 4;
result.rdlength = unpack.uint16(raw_packet, internal_offset);
internal_offset += 2;
var data = dns_util.expandRRData(raw_packet, internal_offset, result);
if(data) {
result.data = data;
}
// skip rdata. TODO: store the rdata somewhere?
internal_offset += result.rdlength;
return internal_offset;
},
decodeRRs: function(raw_packet, offset, internal_offset, count, results) {
for (i = 0; i < count; i++) {
results[i] = {};
internal_offset = dns_util.decodeRR(raw_packet, offset, internal_offset, results[i]);
}
return internal_offset;
}
};
decode.dns = function (raw_packet, offset) {
var ret = {}, i, internal_offset, question_done, len, parts;
// http://tools.ietf.org/html/rfc1035
ret.header = {};
ret.header.id = unpack.uint16(raw_packet, offset); // 0, 1
ret.header.qr = (raw_packet[offset + 2] & 128) >> 7;
ret.header.opcode = (raw_packet[offset + 2] & 120) >> 3;
ret.header.aa = (raw_packet[offset + 2] & 4) >> 2;
ret.header.tc = (raw_packet[offset + 2] & 2) >> 1;
ret.header.rd = raw_packet[offset + 2] & 1;
ret.header.ra = (raw_packet[offset + 3] & 128) >> 7;
ret.header.z = 0; // spec says this MUST always be 0
ret.header.rcode = raw_packet[offset + 3] & 15;
ret.header.qdcount = unpack.uint16(raw_packet, offset + 4); // 4, 5
ret.header.ancount = unpack.uint16(raw_packet, offset + 6); // 6, 7
ret.header.nscount = unpack.uint16(raw_packet, offset + 8); // 8, 9
ret.header.arcount = unpack.uint16(raw_packet, offset + 10); // 10, 11
internal_offset = offset + 12;
ret.question = [];