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packet.lua
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packet.lua
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local hex = require 'eco.encoding.hex'
local nl80211 = require 'eco.nl80211'
local socket = require 'eco.socket'
local M = {}
local methods_decap = {}
local mtable_decap = {
__index = methods_decap
}
local protos = {
[socket.ETH_P_8021Q] = {
name = '8021Q',
next = function(data)
if #data < 4 then
return nil, 'not a valid 8021Q packet'
end
local tci = string.unpack('>I2', data:sub(1))
return setmetatable({
name = '8021Q',
pri = tci >> 13,
vid = tci & 0xfff,
proto = string.unpack('>I2', data:sub(3)),
data = data:sub(5)
}, mtable_decap)
end
},
[socket.ETH_P_ARP] = {
name = 'ARP',
next = function(data)
if #data < 8 then
return nil, 'not a valid ARP packet'
end
local pkt = {
name = 'ARP',
ar_hrd = string.unpack('>I2', data:sub(1)),
ar_pro = string.unpack('>I2', data:sub(3)),
ar_hln = data:byte(5),
ar_pln = data:byte(6),
op = string.unpack('>I2', data:sub(7))
}
if #data < 8 + pkt.ar_hln * 2 + pkt.ar_pln * 2 then
return nil, 'not a valid ARP packet'
end
if pkt.ar_hrd == socket.ARPHRD_ETHER and pkt.ar_pro == socket.ETH_P_IP then
pkt.sha = hex.encode(data:sub(9, 14), ':')
pkt.sip = socket.inet_ntop(socket.AF_INET, data:sub(15))
pkt.tha = hex.encode(data:sub(19, 24), ':')
pkt.tip = socket.inet_ntop(socket.AF_INET, data:sub(25))
end
return setmetatable(pkt, mtable_decap)
end
},
[socket.ETH_P_IP] = {
name = 'IP',
next = function(data)
local ihl = 20
if #data < ihl then
return nil, 'not a valid IPv4 packet'
end
local byte1 = data:byte(1)
local version = byte1 >> 4
ihl = byte1 & 0xf
if #data < ihl * 4 then
return nil, 'not a valid IPv4 packet'
end
return setmetatable({
name = 'IP',
version = version,
ihl = ihl,
tos = data:byte(2),
tot_len = string.unpack('>I2', data:sub(3)),
id = string.unpack('>I2', data:sub(5)),
frag_off = string.unpack('>I2', data:sub(7)),
ttl = data:byte(9),
protocol = data:byte(10),
check = string.unpack('>I2', data:sub(12)),
saddr = socket.inet_ntop(socket.AF_INET, data:sub(17)),
daddr = socket.inet_ntop(socket.AF_INET, data:sub(13)),
data = data:sub(ihl * 4 + 1)
}, mtable_decap)
end
},
[socket.ETH_P_IPV6] = {
name = 'IPV6',
next = function(data)
if #data < 40 then
return nil, 'not a valid IPV6 packet'
end
local byte1 = data:byte(1)
local version = byte1 >> 4
local priority = byte1 & 0xf
local pkt = {
name = 'IPV6',
version = version,
priority = priority,
payload_len = string.unpack('>I2', data:sub(5)),
nexthdr = data:byte(7),
hop_limit = data:byte(8),
saddr = socket.inet_ntop(socket.AF_INET6, data:sub(9)),
daddr = socket.inet_ntop(socket.AF_INET6, data:sub(25)),
data = data:sub(41)
}
local nexthdr = pkt.nexthdr
if nexthdr == socket.IPPROTO_TCP or nexthdr == socket.IPPROTO_UDP then
pkt.protocol = nexthdr
elseif nexthdr == 4 then
pkt.proto = socket.ETH_P_IP -- IPv4 in IPv6
elseif nexthdr == 41 then
pkt.proto = socket.ETH_P_IPV6 -- IPv6 in IPv6
end
return setmetatable(pkt, mtable_decap)
end
}
}
local protocols = {
[socket.IPPROTO_ICMP] = {
name = 'ICMP',
next = function(data)
if #data < 8 then
return nil, 'not a valid ICMP packet'
end
local typ, code = data:byte(1, 2)
local pkt = {
name = 'ICMP',
type = typ,
code = code,
checksum = string.unpack('>I2', data:sub(3))
}
if typ == socket.ICMP_ECHO or typ == socket.ICMP_ECHOREPLY then
pkt.id = string.unpack('>I2', data:sub(5))
pkt.sequence = string.unpack('>I2', data:sub(7))
elseif typ == socket.ICMP_REDIRECT then
pkt.gateway = socket.inet_ntop(socket.AF_INET, data:sub(5))
end
pkt.data = data:sub(9)
return setmetatable(pkt, mtable_decap)
end
},
[socket.IPPROTO_ICMPV6] = {
name = 'ICMPV6',
next = function(data)
if #data < 8 then
return nil, 'not a valid ICMPV6 packet'
end
local typ, code = data:byte(1, 2)
local pkt = {
name = 'ICMPV6',
type = typ,
code = code,
checksum = string.unpack('>I2', data:sub(3))
}
if typ == socket.ICMPV6_ECHO_REQUEST or typ == socket.ICMPV6_ECHO_REPLY then
pkt.id = string.unpack('>I2', data:sub(5))
pkt.sequence = string.unpack('>I2', data:sub(7))
end
pkt.data = data:sub(9)
return setmetatable(pkt, mtable_decap)
end
},
[socket.IPPROTO_TCP] = {
name = 'TCP',
next = function(data, self)
local thl = 20
if #data < thl then
return nil, 'not a valid TCP packet'
end
local doff = data:byte(13) >> 4
thl = doff * 4
local len = self.tot_len - self.ihl * 4 - thl
local byte14 = data:byte(14)
return setmetatable({
name = 'TCP',
source = string.unpack('>I2', data),
dest = string.unpack('>I2', data:sub(3)),
seq = string.unpack('>I4', data:sub(5)),
ack_seq = string.unpack('>I4', data:sub(9)),
doff = doff,
cwr = (byte14 >> 7) & 0x1 == 1,
ece = (byte14 >> 6) & 0x1 == 1,
urg = (byte14 >> 5) & 0x1 == 1,
ack = (byte14 >> 4) & 0x1 == 1,
psh = (byte14 >> 3) & 0x1 == 1,
rst = (byte14 >> 2) & 0x1 == 1,
syn = (byte14 >> 1) & 0x1 == 1,
fin = byte14 & 0x1 == 1,
window = string.unpack('>I2', data:sub(15)),
check = string.unpack('>I2', data:sub(17)),
urg_ptr = string.unpack('>I2', data:sub(19)),
data = data:sub(thl + 1, thl + len)
}, mtable_decap)
end
},
[socket.IPPROTO_UDP] = {
name = 'UDP',
next = function(data)
local uhl = 8
if #data < uhl then
return nil, 'not a valid UDP packet'
end
local len = string.unpack('>I2', data:sub(5))
local data_len = len - uhl
return setmetatable({
name = 'UDP',
source = string.unpack('>I2', data),
dest = string.unpack('>I2', data:sub(3)),
len = len,
check = string.unpack('>I2', data:sub(7)),
data = data:sub(uhl + 1, uhl + data_len)
}, mtable_decap)
end
}
}
local tostrings = {
['80211'] = function(self)
local typ, subtype = self.type, self.subtype
local name = nl80211.ftype_name(typ, subtype)
local fields = {}
if self.addr1 then
if self.addr2 then
fields[#fields + 1] = self.addr2 .. '->' .. self.addr1
else
fields[#fields + 1] = self.addr1
end
end
if name then
fields[#fields + 1] = name
else
fields[#fields + 1] = 'type ' .. string.format('0x%02x', typ)
fields[#fields + 1] = 'subtype ' .. string.format('0x%02x', subtype)
end
if typ == nl80211.FTYPE_MGMT then
if self.beacon_interval then
fields[#fields + 1] = 'BI=' .. self.beacon_interval
end
if self.ssid then
fields[#fields + 1] = 'SSID="' .. self.ssid .. '"'
end
end
return table.concat(fields, ' ')
end,
['ETHER'] = function(self)
local proto = self.proto
local p = protos[self.proto]
return self.source .. '->' .. self.dest .. ' ' .. (p and p.name or proto)
end,
['8021Q'] = function(self)
local proto = self.proto
local p = protos[self.proto]
return 'pri ' .. self.pri .. ' vid ' .. self.vid .. ' ' .. (p and p.name or proto)
end,
['ARP'] = function(self)
if self.ar_hrd == socket.ARPHRD_ETHER and self.ar_pro == socket.ETH_P_IP then
if self.op == socket.ARPOP_REQUEST then
return string.format('Request who-has %s (%s) tell %s', self.tip, self.tha, self.sip)
else
return string.format('Reply %s is-at %s', self.sip, self.sha)
end
end
return ''
end,
['ICMP'] = function(self)
local typ = self.type
local fields = {}
if typ == socket.ICMP_ECHO or typ == socket.ICMP_ECHOREPLY then
fields[#fields + 1] = typ == socket.ICMP_ECHO and 'ECHO' or 'ECHOREPLY'
fields[#fields + 1] = 'seq ' .. self.sequence
fields[#fields + 1] = 'id ' .. self.id
else
fields[#fields + 1] = 'type ' .. typ
end
fields[#fields + 1] = 'len ' .. #self.data
return table.concat(fields, ' ')
end,
['ICMPV6'] = function(self)
local typ = self.type
local fields = {}
if typ == socket.ICMPV6_ECHO_REQUEST or typ == socket.ICMPV6_ECHO_REPLY then
fields[#fields + 1] = typ == socket.ICMPV6_ECHO_REQUEST and 'ECHO' or 'ECHOREPLY'
fields[#fields + 1] = 'seq ' .. self.sequence
fields[#fields + 1] = 'id ' .. self.id
else
fields[#fields + 1] = 'type ' .. typ
end
fields[#fields + 1] = 'len ' .. #self.data
return table.concat(fields, ' ')
end,
['IP'] = function(self)
local protocol = self.protocol
local p = protocols[protocol]
return self.saddr .. '->' .. self.daddr .. ' ' .. (p and p.name or protocol)
end,
['IPV6'] = function(self)
return self.saddr .. '->' .. self.daddr
end,
['TCP'] = function(self)
local tokens = {self.source .. '->' .. self.dest, 'len ' .. #self.data}
for _, flag in ipairs({ 'syn', 'ack', 'rst', 'fin' }) do
if self[flag] then
tokens[#tokens + 1] = flag:upper()
end
end
return table.concat(tokens, ' ')
end,
['UDP'] = function(self)
return self.source .. '->' .. self.dest .. ' len ' .. #self.data
end
}
function mtable_decap:__tostring()
if tostrings[self.name] then
return tostrings[self.name](self)
end
return ''
end
function methods_decap:next()
local data = self.data
local proto = self.proto
if proto then
if not protos[proto] then
return nil, 'unknown L3 proto "' .. proto .. '"'
end
return protos[proto].next(data)
end
local protocol = self.protocol
if protocol then
if not protocols[protocol] then
return nil, 'unknown L4 protocol "' .. protocol .. '"'
end
return protocols[protocol].next(data, self)
end
return nil, 'no upper protocol layer'
end
function M.from_icmp(data)
return protocols[socket.IPPROTO_ICMP].next(data)
end
function M.from_icmp6(data)
return protocols[socket.IPPROTO_ICMPV6].next(data)
end
function M.from_ip(data)
return protos[socket.ETH_P_IP].next(data)
end
function M.from_ip6(data)
return protos[socket.ETH_P_IPV6].next(data)
end
function M.from_ether(data)
assert(type(data) == 'string')
if #data < 14 then
return nil, 'not a valid ether packet'
end
local dest = hex.encode(data:sub(1, 6), ':')
local source = hex.encode(data:sub(7, 12), ':')
local proto = string.unpack('>I2', data:sub(13))
return setmetatable({
name = 'ETHER',
dest = dest,
source = source,
proto = proto,
data = data:sub(15)
}, mtable_decap)
end
local function parse_80211_ie(pkt, data)
while #data >= 2 and #data - 2 >= data:byte(2) do
local ie_type = data:byte(1)
local ie_len = data:byte(2)
data = data:sub(3)
if ie_type == 0 then
pkt.ssid = data:sub(1, ie_len)
end
data = data:sub(ie_len + 1)
end
end
function M.from_radiotap(data)
assert(type(data) == 'string')
if #data < 14 then
return nil, 'not a valid radiotap packet'
end
local header_len = string.unpack('<I2', data:sub(3))
data = data:sub(header_len + 1)
local fc = string.unpack('<I2', data:sub(1))
local typ = (fc >> 2) & 0x3
local subtype = (fc >> 4) & 0xf
local pkt = {
name = '80211',
version = fc & 0x3,
type = typ,
subtype = subtype,
to_ds = (fc >> 8) & 01 == 1,
from_ds = (fc >> 9) & 0x1 == 1,
more_frag = (fc >> 10) & 0x1 == 1,
retry = (fc >> 11) & 0x1 == 1,
pwr_mgmt = (fc >> 12) & 0x1 == 1,
more_data = (fc >> 13) & 0x1 == 1,
protected = (fc >> 14) & 0x1 == 1,
plus_htc = (fc >> 15) & 0x1 == 1,
duration = string.unpack('<I2', data:sub(3)),
addr1 = hex.encode(data:sub(5, 10), ':')
}
if typ == nl80211.FTYPE_MGMT then
pkt.addr2 = hex.encode(data:sub(11, 16), ':')
pkt.addr3 = hex.encode(data:sub(17, 22), ':')
data = data:sub(pkt.plus_htc and 29 or 25)
if subtype == nl80211.STYPE_BEACON or subtype == nl80211.STYPE_PROBE_RESP then
pkt.timestamp = string.unpack('<I8', data:sub(1))
pkt.beacon_interval = string.unpack('<I2', data:sub(9))
pkt.capability = string.unpack('<I2', data:sub(11))
parse_80211_ie(pkt, data:sub(13))
elseif subtype == nl80211.STYPE_PROBE_REQ then
parse_80211_ie(pkt, data)
end
elseif typ == nl80211.FTYPE_DATA then
pkt.addr2 = hex.encode(data:sub(11, 16), ':')
pkt.addr3 = hex.encode(data:sub(17, 22), ':')
if pkt.from_ds and pkt.to_ds then
pkt.addr4 = hex.encode(data:sub(23, 28), ':')
end
end
return setmetatable(pkt, mtable_decap)
end
local function csum_icmp(data)
local count = #data
local sum = 0
local i = 1
while i < count do
sum = sum + data:byte(i) * 256 + data:byte(i + 1)
i = i + 2
end
if i == count then
sum = sum + data:byte(i) * 256
end
sum = (sum >> 16) + (sum & 0xffff)
sum = sum + (sum >> 16)
return ~sum & 0xffff
end
function M.icmp(typ, code, id, sequence, data, checksum)
assert(typ == socket.ICMP_ECHO or typ == socket.ICMP_ECHOREPLY)
data = data or ''
local check = 0
local buf = {
string.char(typ, code),
string.pack('>I2', check),
string.pack('>I2', id),
string.pack('>I2', sequence),
data
}
if checksum then
check = csum_icmp(table.concat(buf))
buf[2] = string.pack('>I2', check)
end
return table.concat(buf)
end
function M.icmp6(typ, code, id, sequence, data, checksum)
assert(typ == socket.ICMPV6_ECHO_REQUEST or typ == socket.ICMPV6_ECHO_REPLY)
data = data or ''
local check = 0
local buf = {
string.char(typ, code),
string.pack('>I2', check),
string.pack('>I2', id),
string.pack('>I2', sequence),
data
}
if checksum then
check = csum_icmp(table.concat(buf))
buf[2] = string.pack('>I2', check)
end
return table.concat(buf)
end
local function csum_tcpudp(saddr, daddr, protocol, pkt)
local function sum16bits(data)
local sum = 0
for i = 1, #data, 2 do
if i + 1 <= #data then
sum = sum + (data:byte(i) * 256 + data:byte(i + 1))
else
sum = sum + (data:byte(i) * 256)
end
if sum > 0xffff then
sum = (sum & 0xffff) + (sum >> 16)
end
end
return sum
end
local pseudo_header = table.concat({
string.pack('I4', socket.inet_aton(saddr)),
string.pack('I4', socket.inet_aton(daddr)),
'\0',
string.char(protocol),
string.pack(">I2", #pkt)
})
local sum = sum16bits(pseudo_header) + sum16bits(pkt)
while sum > 0xffff do
sum = (sum & 0xffff) + (sum >> 16)
end
return ~sum & 0xffff
end
function M.udp(source, dest, data, saddr, daddr)
data = data or ''
local len = 8 + #data
local check = 0
local buf = {
string.pack('>I2', source),
string.pack('>I2', dest),
string.pack('>I2', len),
string.pack('>I2', check),
data
}
if saddr and daddr then
check = csum_tcpudp(saddr, daddr, socket.IPPROTO_UDP, table.concat(buf))
buf[4] = string.pack('>I2', check)
end
return table.concat(buf)
end
function M.tcp(source, dest, seq, ack_seq, flags, window, saddr, daddr, data)
flags = flags or {}
data = data or ''
local hl = 5
local check = 0
local flag = 0
local urg_ptr = 0
flag = flag | (flags.cwr and (1 << 7) or 0)
flag = flag | (flags.ece and (1 << 6) or 0)
flag = flag | (flags.urg and (1 << 5) or 0)
flag = flag | (flags.ack and (1 << 4) or 0)
flag = flag | (flags.psh and (1 << 3) or 0)
flag = flag | (flags.rst and (1 << 2) or 0)
flag = flag | (flags.syn and (1 << 1) or 0)
flag = flag | (flags.fin and (1 << 0) or 0)
local buf = {
string.pack('>I2', source),
string.pack('>I2', dest),
string.pack('>I4', seq),
string.pack('>I4', ack_seq),
string.char(hl << 4, flag),
string.pack('>I2', window),
string.pack('>I2', check),
string.pack('>I2', urg_ptr),
data
}
check = csum_tcpudp(saddr, daddr, socket.IPPROTO_TCP, table.concat(buf))
buf[7] = string.pack('>I2', check)
return table.concat(buf)
end
function M.ip(saddr, daddr, protocol, data)
data = data or ''
local version = 4
local ihl = 5
local tos = 0
local tot_len = ihl * 4 + #data
local id = 0
local frag_off = 0
local ttl = 64
local check = 0
local header = {
string.char(version << 4 | ihl, tos),
string.pack('>I2', tot_len),
string.pack('>I2', id),
string.pack('>I2', frag_off),
string.char(ttl, protocol),
string.pack('>I2', check),
string.pack('I4', socket.inet_aton(saddr)),
string.pack('I4', socket.inet_aton(daddr))
}
local buf = table.concat(header)
for i = 1, #buf, 2 do
check = check + (buf:byte(i) << 8) + buf:byte(i + 1)
if check > 0xffff then
check = (check & 0xffff) + (check >> 16)
end
end
check = ~check & 0xffff
header[6] = string.pack('>I2', check)
return table.concat(header) .. data
end
function M.arp(op, sha, sip, tha, tip)
sha = sha or '00:00:00:00:00:00'
sip = sip or '0.0.0.0'
tha = tha or '00:00:00:00:00:00'
tip = tip or '0.0.0.0'
local buf = {
string.pack('>I2', socket.ARPHRD_ETHER),
string.pack('>I2', socket.ETH_P_IP),
string.char(6, 4), -- hardware address length and proto address length
string.pack('>I2', op),
hex.decode(sha:gsub(':', '')),
string.pack('I4', socket.inet_aton(sip)),
hex.decode(tha:gsub(':', '')),
string.pack('I4', socket.inet_aton(tip))
}
return table.concat(buf)
end
function M.ether(source, dest, proto, data)
data = data or ''
local buf = {
hex.decode(dest:gsub(':', '')),
hex.decode(source:gsub(':', '')),
string.pack('>I2', proto),
data
}
return table.concat(buf)
end
return M