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Switch to string packing instead of bin packing and return order for asn1-related libs

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dmiller
2017-03-29 20:42:01 +00:00
parent 3dec043ead
commit 4cef14a873
8 changed files with 120 additions and 134 deletions
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56
nselib/asn1.lua
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@@ -17,7 +17,6 @@
-- o Each script or library should now create its own Encoder and Decoder instance
--
local bin = require "bin"
local bit = require "bit"
local math = require "math"
local stdnse = require "stdnse"
@@ -62,7 +61,7 @@ ASN1Decoder = {
-- Boolean
self.decoder["\x01"] = function( self, encStr, elen, pos )
local val = string.byte(encStr, pos)
return pos + 1, val ~= 0xFF
return val ~= 0xFF, pos + 1
end
-- Integer
@@ -72,12 +71,12 @@ ASN1Decoder = {
-- Octet String
self.decoder["\x04"] = function( self, encStr, elen, pos )
return bin.unpack("A" .. elen, encStr, pos)
return string.unpack("c" .. elen, encStr, pos)
end
-- Null
self.decoder["\x05"] = function( self, encStr, elen, pos )
return pos, false
return false, pos
end
-- Object Identifier
@@ -107,8 +106,8 @@ ASN1Decoder = {
-- @param encStr Encoded string
-- @param elen Length of the object in bytes
-- @param pos Current position in the string
-- @return The position after decoding
-- @return The decoded object
-- @return The position after decoding
--- Allows for registration of additional tag decoders
-- @name ASN1Decoder.registerTagDecoders
@@ -125,21 +124,21 @@ ASN1Decoder = {
-- @name ASN1Decoder.decode
-- @param encStr Encoded string.
-- @param pos Current position in the string.
-- @return The position after decoding
-- @return The decoded value(s).
-- @return The position after decoding
decode = function(self, encStr, pos)
local etype, elen
local newpos = pos
etype, newpos = string.unpack("c1", encStr, newpos)
newpos, elen = self.decodeLength(encStr, newpos)
elen, newpos = self.decodeLength(encStr, newpos)
if self.decoder[etype] then
return self.decoder[etype]( self, encStr, elen, newpos )
else
stdnse.debug1("no decoder for etype: " .. etype)
return newpos, nil
return nil, newpos
end
end,
@@ -149,23 +148,22 @@ ASN1Decoder = {
-- @name ASN1Decoder.decodeLength
-- @param encStr Encoded string.
-- @param pos Current position in the string.
-- @return The position after decoding.
-- @return The length of the following value.
-- @return The position after decoding.
decodeLength = function(encStr, pos)
local elen
pos, elen = bin.unpack('C', encStr, pos)
local elen, newpos = string.unpack('B', encStr, pos)
if (elen > 128) then
elen = elen - 128
local elenCalc = 0
local elenNext
for i = 1, elen do
elenCalc = elenCalc * 256
pos, elenNext = bin.unpack("C", encStr, pos)
elenNext, newpos = string.unpack('B', encStr, newpos)
elenCalc = elenCalc + elenNext
end
elen = elenCalc
end
return pos, elen
return elen, newpos
end,
---
@@ -174,20 +172,19 @@ ASN1Decoder = {
-- @param encStr Encoded string.
-- @param len Length of sequence in bytes.
-- @param pos Current position in the string.
-- @return The position after decoding.
-- @return The decoded sequence as a table.
-- @return The position after decoding.
decodeSeq = function(self, encStr, len, pos)
local seq = {}
local sPos = 1
local sStr
pos, sStr = bin.unpack("A" .. len, encStr, pos)
local sStr, newpos = string.unpack("c" .. len, encStr, pos)
while (sPos < len) do
local newSeq
sPos, newSeq = self:decode(sStr, sPos)
newSeq, sPos = self:decode(sStr, sPos)
if ( not(newSeq) and self.stoponerror ) then break end
table.insert(seq, newSeq)
end
return pos, seq
return seq, newpos
end,
-- Decode one component of an OID from a byte string. 7 bits of the component
@@ -200,11 +197,11 @@ ASN1Decoder = {
local n = 0
repeat
pos, octet = bin.unpack("C", encStr, pos)
octet, pos = string.unpack("B", encStr, pos)
n = n * 128 + bit.band(0x7F, octet)
until octet < 128
return pos, n
return n, pos
end,
--- Decodes an OID from a sequence of bytes.
@@ -212,8 +209,8 @@ ASN1Decoder = {
-- @param encStr Encoded string.
-- @param len Length of sequence in bytes.
-- @param pos Current position in the string.
-- @return The position after decoding.
-- @return The OID as an array.
-- @return The position after decoding.
decodeOID = function(self, encStr, len, pos)
local last
local oid = {}
@@ -222,7 +219,7 @@ ASN1Decoder = {
last = pos + len - 1
if pos <= last then
oid._snmp = '\x06'
pos, octet = bin.unpack("C", encStr, pos)
octet, pos = string.unpack("B", encStr, pos)
oid[2] = math.fmod(octet, 40)
octet = octet - oid[2]
oid[1] = octet//40
@@ -230,11 +227,11 @@ ASN1Decoder = {
while pos <= last do
local c
pos, c = self.decode_oid_component(encStr, pos)
c, pos = self.decode_oid_component(encStr, pos)
oid[#oid + 1] = c
end
return pos, oid
return oid, pos
end,
---
@@ -243,11 +240,10 @@ ASN1Decoder = {
-- @param encStr Encoded string.
-- @param len Length of integer in bytes.
-- @param pos Current position in the string.
-- @return The position after decoding.
-- @return The decoded integer.
-- @return The position after decoding.
decodeInt = function(encStr, len, pos)
local value, pos = string.unpack(">i" .. len, encStr, pos)
return pos, value
return string.unpack(">i" .. len, encStr, pos)
end,
}
@@ -392,7 +388,7 @@ ASN1Encoder = {
local valStr = ""
while (val > 0) do
lsb = math.fmod(val, 256)
valStr = valStr .. bin.pack("C", lsb)
valStr = valStr .. string.pack("B", lsb)
val = math.floor(val/256)
end
if lsb > 127 then -- two's complement collision
@@ -410,12 +406,12 @@ ASN1Encoder = {
local valStr = ""
while (tcval > 0) do
lsb = math.fmod(tcval, 256)
valStr = valStr .. bin.pack("C", lsb)
valStr = valStr .. string.pack("B", lsb)
tcval = math.floor(tcval/256)
end
return string.reverse(valStr)
else -- val == 0
return bin.pack("x")
return '\0'
end
end,