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Clean up packet.lua, add a few unit tests.

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This commit is contained in:
dmiller
2020-11-04 22:26:58 +00:00
parent 82be54a353
commit 041838d986
1 changed files with 76 additions and 86 deletions
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162
nselib/packet.lua
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@@ -7,6 +7,7 @@
local ipOps = require "ipOps" local ipOps = require "ipOps"
local stdnse = require "stdnse" local stdnse = require "stdnse"
local string = require "string" local string = require "string"
local unittest = require "unittest"
_ENV = stdnse.module("packet", stdnse.seeall) _ENV = stdnse.module("packet", stdnse.seeall)
@@ -15,29 +16,22 @@ _ENV = stdnse.module("packet", stdnse.seeall)
-- @param b A byte string. -- @param b A byte string.
-- @param i Offset. -- @param i Offset.
-- @return An 8-bit integer. -- @return An 8-bit integer.
function u8(b, i) local function u8(b, i)
return string.byte(b, i+1) return b:byte(i+1)
end end
--- Get a 16-bit integer at a 0-based byte offset in a byte string. --- Get a 16-bit integer at a 0-based byte offset in a byte string.
-- @param b A byte string. -- @param b A byte string.
-- @param i Offset. -- @param i Offset.
-- @return A 16-bit integer. -- @return A 16-bit integer.
function u16(b, i) local function u16(b, i)
local b1,b2 return (">I2"):unpack(b, i+1)
b1, b2 = string.byte(b, i+1), string.byte(b, i+2)
-- 2^8 2^0
return b1*256 + b2
end end
--- Get a 32-bit integer at a 0-based byte offset in a byte string. --- Get a 32-bit integer at a 0-based byte offset in a byte string.
-- @param b A byte string. -- @param b A byte string.
-- @param i Offset. -- @param i Offset.
-- @return A 32-bit integer. -- @return A 32-bit integer.
function u32(b,i) local function u32(b,i)
local b1,b2,b3,b4 return (">I4"):unpack(b, i+1)
b1, b2 = string.byte(b, i+1), string.byte(b, i+2)
b3, b4 = string.byte(b, i+3), string.byte(b, i+4)
-- 2^24 2^16 2^8 2^0
return b1*16777216 + b2*65536 + b3*256 + b4
end end
--- Set an 8-bit integer at a 0-based byte offset in a byte string --- Set an 8-bit integer at a 0-based byte offset in a byte string
@@ -45,7 +39,7 @@ end
-- @param b A byte string. -- @param b A byte string.
-- @param i Offset. -- @param i Offset.
-- @param num Integer to store. -- @param num Integer to store.
function set_u8(b, i, num) local function set_u8(b, i, num)
local s = string.char(num & 0xff) local s = string.char(num & 0xff)
return b:sub(0+1, i+1-1) .. s .. b:sub(i+1+1) return b:sub(0+1, i+1-1) .. s .. b:sub(i+1+1)
end end
@@ -54,38 +48,16 @@ end
-- @param b A byte string. -- @param b A byte string.
-- @param i Offset. -- @param i Offset.
-- @param num Integer to store. -- @param num Integer to store.
function set_u16(b, i, num) local function set_u16(b, i, num)
local s = string.char((num >> 8) & 0xff) .. string.char(num & 0xff) return b:sub(0+1, i+1-1) .. (">I2"):pack(num) .. b:sub(i+1+2)
return b:sub(0+1, i+1-1) .. s .. b:sub(i+1+2)
end end
--- Set a 32-bit integer at a 0-based byte offset in a byte string --- Set a 32-bit integer at a 0-based byte offset in a byte string
-- (big-endian). -- (big-endian).
-- @param b A byte string. -- @param b A byte string.
-- @param i Offset. -- @param i Offset.
-- @param num Integer to store. -- @param num Integer to store.
function set_u32(b,i, num) local function set_u32(b,i, num)
local s = string.char((num >> 24) & 0xff) .. return b:sub(0+1, i+1-1) .. (">I4"):pack(num) .. b:sub(i+1+4)
string.char((num >>16) & 0xff) ..
string.char((num >> 8) & 0xff) ..
string.char(num & 0xff)
return b:sub(0+1, i+1-1) .. s .. b:sub(i+1+4)
end
--- Get a 1-byte string from a number.
-- @param num A number.
function numtostr8(num)
return string.char(num)
end
--- Get a 2-byte string from a number.
-- (big-endian)
-- @param num A number.
function numtostr16(num)
return set_u16("..", 0, num)
end
--- Get a 4-byte string from a number.
-- (big-endian)
-- @param num A number.
function numtostr32(num)
return set_u32("....", 0, num)
end end
--- Calculate a standard Internet checksum. --- Calculate a standard Internet checksum.
@@ -93,20 +65,18 @@ end
-- @return Checksum. -- @return Checksum.
function in_cksum(b) function in_cksum(b)
local sum = 0 local sum = 0
local i
-- Note we are using 0-based indexes here. -- Pad to even length, then sum up
i = 0 string.gsub(b .. ("\0"):rep(#b % 2), "..", function(twobytes)
while i < b:len() - 1 do sum = sum + (">I2"):unpack(twobytes)
sum = sum + u16(b, i) end)
i = i + 2
end local shifted = sum >> 16
if i < b:len() then while shifted > 0 do
sum = sum + u8(b, i) * 256 sum = (sum & 0xffff) + shifted
shifted = sum >> 16
end end
sum = (sum >> 16) + (sum & 0xffff)
sum = sum + (sum >> 16)
sum = ~sum sum = ~sum
sum = (sum & 0xffff) -- truncate to 16 bits sum = (sum & 0xffff) -- truncate to 16 bits
return sum return sum
@@ -277,11 +247,10 @@ end
-- @param ip6_tc Number stands for Traffic Class. -- @param ip6_tc Number stands for Traffic Class.
-- @param ip6_fl Number stands for Flow Label. -- @param ip6_fl Number stands for Flow Label.
-- @return The first four-byte string of an IPv6 header. -- @return The first four-byte string of an IPv6 header.
function ipv6_hdr_pack_tc_fl(ip6_tc, ip6_fl) local function ipv6_hdr_tc_fl(ip6_tc, ip6_fl)
local ver_tc_fl = (6 << 28) + return (6 << 28) +
((ip6_tc & 0xFF) << 20) + ((ip6_tc & 0xFF) << 20) +
(ip6_fl & 0xFFFFF) (ip6_fl & 0xFFFFF)
return numtostr32(ver_tc_fl)
end end
--- Build an IPv6 packet. --- Build an IPv6 packet.
-- @param src 16-byte string of the source IPv6 address. -- @param src 16-byte string of the source IPv6 address.
@@ -301,13 +270,13 @@ function Packet:build_ipv6_packet(src, dst, nx_hdr, payload, h_limit, t_class, f
self.ip6_fl = f_label or self.ip6_fl or 1 self.ip6_fl = f_label or self.ip6_fl or 1
self.ip6_hlimit = h_limit or self.ip6_hlimit or 255 self.ip6_hlimit = h_limit or self.ip6_hlimit or 255
self.ip6_plen = #(self.exheader or "")+#(self.l4_packet or "") self.ip6_plen = #(self.exheader or "")+#(self.l4_packet or "")
self.buf = self.buf = (">I4I2BBc16c16"):pack(
ipv6_hdr_pack_tc_fl(self.ip6_tc, self.ip6_fl) .. ipv6_hdr_tc_fl(self.ip6_tc, self.ip6_fl),
numtostr16(self.ip6_plen) .. --payload length self.ip6_plen, --payload length
string.char(self.ip6_nhdr) .. --next header self.ip6_nhdr, --next header
string.char(self.ip6_hlimit) .. --hop limit self.ip6_hlimit, --hop limit
self.ip_bin_src .. --Source self.ip_bin_src, --Source
self.ip_bin_dst ..--dest self.ip_bin_dst) .. --dest
(self.exheader or "").. (self.exheader or "")..
(self.l4_packet or "") (self.l4_packet or "")
end end
@@ -326,7 +295,8 @@ end
--- Count IPv6 checksum. --- Count IPv6 checksum.
-- @return the checksum. -- @return the checksum.
function Packet:count_ipv6_pseudoheader_cksum() function Packet:count_ipv6_pseudoheader_cksum()
local pseudoheader = self.ip_bin_src .. self.ip_bin_dst .. numtostr16(#self.l4_packet) .. "\0\0\0" .. string.char(self.ip6_nhdr) local pseudoheader = (">c16c16I2xxxB"):pack(
self.ip_bin_src, self.ip_bin_dst, #self.l4_packet, self.ip6_nhdr)
local ck_content = pseudoheader .. self.l4_packet local ck_content = pseudoheader .. self.l4_packet
return in_cksum(ck_content) return in_cksum(ck_content)
end end
@@ -348,9 +318,7 @@ function Packet:build_icmpv6_header(icmpv6_type, icmpv6_code, icmpv6_payload, ip
self.ip_bin_src = ip_bin_src or self.ip_bin_src self.ip_bin_src = ip_bin_src or self.ip_bin_src
self.ip_bin_dst = ip_bin_dst or self.ip_bin_dst self.ip_bin_dst = ip_bin_dst or self.ip_bin_dst
self.l4_packet = self.l4_packet = ("BBxx"):pack(self.icmpv6_type, self.icmpv6_code) ..
string.char(self.icmpv6_type,self.icmpv6_code) ..
"\0\0" .. --checksum
(self.icmpv6_payload or "") (self.icmpv6_payload or "")
local check_sum = self:count_ipv6_pseudoheader_cksum() local check_sum = self:count_ipv6_pseudoheader_cksum()
self:set_icmp6_cksum(check_sum) self:set_icmp6_cksum(check_sum)
@@ -383,7 +351,7 @@ function Packet:build_icmpv6_echo_request(id, sequence, data, mac_src, mac_dst,
self.echo_seq = sequence or self.echo_seq or 0xbeef self.echo_seq = sequence or self.echo_seq or 0xbeef
self.echo_data = data or self.echo_data or "" self.echo_data = data or self.echo_data or ""
self.icmpv6_payload = numtostr16(self.echo_id) .. numtostr16(self.echo_seq) .. self.echo_data self.icmpv6_payload = (">I2I2"):pack(self.echo_id, self.echo_seq) .. self.echo_data
end end
--- Set an ICMPv6 option message. --- Set an ICMPv6 option message.
function Packet:set_icmpv6_option(opt_type,msg) function Packet:set_icmpv6_option(opt_type,msg)
@@ -412,18 +380,19 @@ function Packet:build_ip_packet(src, dst, payload, dsf, id, flags, off, ttl, pro
self.ip_id = id or self.ip_id or 0xbeef self.ip_id = id or self.ip_id or 0xbeef
self.ip_off = off or self.ip_off or 0 self.ip_off = off or self.ip_off or 0
self.ip_ttl = ttl or self.ip_ttl or 255 self.ip_ttl = ttl or self.ip_ttl or 255
self.buf = self.buf = (">BBI2I2BBBBI2c4c4"):pack(
numtostr8((self.ip_v << 4) + 20 / 4) .. -- version and header length (self.ip_v << 4) + 20 / 4, -- version and header length
numtostr8(self.ip_dsf) .. self.ip_dsf,
numtostr16(#self.l3_packet + 20) .. #self.l3_packet + 20,
numtostr16(self.ip_id) .. self.ip_id,
numtostr8(self.flags) .. self.flags,
numtostr8(self.ip_off) .. self.ip_off,
numtostr8(self.ip_ttl) .. self.ip_ttl,
numtostr8(self.ip_p) .. self.ip_p,
numtostr16(0) .. -- checksum 0, -- checksum
self.ip_bin_src .. --Source self.ip_bin_src, --Source
self.ip_bin_dst --dest self.ip_bin_dst --dest
)
self.buf = set_u16(self.buf, 10, in_cksum(self.buf)) self.buf = set_u16(self.buf, 10, in_cksum(self.buf))
self.buf = self.buf .. self.l3_packet self.buf = self.buf .. self.l3_packet
@@ -441,9 +410,7 @@ function Packet:build_icmp_header(icmp_type, icmp_code, icmp_payload, ip_bin_src
self.ip_bin_src = ip_bin_src or self.ip_bin_src self.ip_bin_src = ip_bin_src or self.ip_bin_src
self.ip_bin_dst = ip_bin_dst or self.ip_bin_dst self.ip_bin_dst = ip_bin_dst or self.ip_bin_dst
self.l3_packet = self.l3_packet = ("BBxx"):pack(self.icmp_type, self.icmp_code) ..
string.char(self.icmp_type,self.icmp_code) ..
"\0\0" .. --checksum
(self.icmp_payload or "") (self.icmp_payload or "")
self.l3_packet = set_u16(self.l3_packet, 2, in_cksum(self.l3_packet)) self.l3_packet = set_u16(self.l3_packet, 2, in_cksum(self.l3_packet))
end end
@@ -471,7 +438,7 @@ function Packet:build_icmp_echo_request(id, seq, data, mac_src, mac_dst, ip_bin_
self.echo_seq = seq or self.echo_seq or 0xbeef self.echo_seq = seq or self.echo_seq or 0xbeef
self.echo_data = data or self.echo_data or "" self.echo_data = data or self.echo_data or ""
self.icmp_payload = numtostr16(self.echo_id) .. numtostr16(self.echo_seq) .. self.echo_data self.icmp_payload = (">I2I2"):pack(self.echo_id, self.echo_seq) .. self.echo_data
end end
@@ -529,7 +496,7 @@ end
function Packet:raw(index, length) function Packet:raw(index, length)
if not index then index = 0 end if not index then index = 0 end
if not length then length = #self.buf-index end if not length then length = #self.buf-index end
return string.char(string.byte(self.buf, index+1, index+1+length-1)) return self.buf:sub(index+1, index+1+length-1)
end end
--- Set an 8-bit integer at a 0-based byte offset in the packet. --- Set an 8-bit integer at a 0-based byte offset in the packet.
@@ -934,8 +901,7 @@ function Packet:tcp_count_checksum()
local b = self.ip_bin_src .. local b = self.ip_bin_src ..
self.ip_bin_dst .. self.ip_bin_dst ..
"\0" .. "\0" ..
string.char(proto) .. (">BI2"):pack(proto, length) ..
set_u16("..", 0, length) ..
self.buf:sub(self.tcp_offset+1) self.buf:sub(self.tcp_offset+1)
self:tcp_set_checksum(in_cksum(b)) self:tcp_set_checksum(in_cksum(b))
@@ -1073,12 +1039,36 @@ function Packet:udp_count_checksum()
local b = self.ip_bin_src .. local b = self.ip_bin_src ..
self.ip_bin_dst .. self.ip_bin_dst ..
"\0" .. "\0" ..
string.char(proto) .. (">BI2"):pack(proto, length) ..
set_u16("..", 0, length) ..
self.buf:sub(self.udp_offset+1) self.buf:sub(self.udp_offset+1)
self:udp_set_checksum(in_cksum(b)) self:udp_set_checksum(in_cksum(b))
end end
if not unittest.testing() then
return _ENV
end
test_suite = unittest.TestSuite:new()
-- Byte setting functions
test_suite:add_test(unittest.equal(set_u8("abc", 1, 0x41), "aAc"), "set_u8")
test_suite:add_test(unittest.equal(set_u16("abcd", 2, 0x4142), "abAB"), "set_u16")
test_suite:add_test(unittest.equal(set_u32("abcdefg", 0, 0x41424344), "ABCDefg"), "set_u32")
-- Packet parsing
local packet1 = "\x45\x00\x00\x62\xaf\xbd\x40\x00\xe3\x06\x03\xf3\x03\x5e\x1e\xa5\xc0\xa8\x01\x3a\x01\xbb\xee\x3e\x74\xd2\x61\xbe\xd5\x66\xb1\x09\x80\x18\x00\x7a\x94\x22\x00\x00\x01\x01\x08\x0a\x73\xab\x53\x92\x05\xe3\x08\xc3\x17\x03\x03\x00\x29\x99\xff\x5d\x17\xe4\x26\x14\xb8\x53\xe3\x76\xdc\xba\xf9\x55\xf7\x52\x5f\xa2\x78\xc3\x4e\x9a\x31\x44\x2d\x67\x9c\x16\xea\x71\xf1\xdb\x0a\xdd\xc1\x92\x46\xa7\xdf\xde"
local pkt_parsed = Packet:new(packet1, #packet1, false)
test_suite:add_test (unittest.not_nil(pkt_parsed), "parse packet")
test_suite:add_test(unittest.equal(pkt_parsed:raw(), packet1), "parse to raw")
-- Checksum tests
pkt_parsed:ip_count_checksum()
test_suite:add_test(unittest.equal(pkt_parsed:raw(), packet1), "IP checksum")
pkt_parsed:tcp_count_checksum()
test_suite:add_test(unittest.equal(pkt_parsed:raw(), packet1), "TCP checksum")
-- TODO: UDP parsing/checksum
-- TODO: IPv6 parsing, ICMPv6 checksum
-- Basically, we need a lot more test coverage here.
return _ENV; return _ENV;