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# Nim-Libp2p
# Copyright (c) 2022 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
# * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.
## This module implements minimal ASN.1 encoding/decoding primitives.
{.push raises: [Defect].}
import stew/[endians2, results, ctops]
export results
# We use `ncrutils` for constant-time hexadecimal encoding/decoding procedures.
import nimcrypto/utils as ncrutils
type
Asn1Error* {.pure.} = enum
Overflow,
Incomplete,
Indefinite,
Incorrect,
NoSupport,
Overrun
Asn1Result*[T] = Result[T, Asn1Error]
Asn1Class* {.pure.} = enum
Universal = 0x00,
Application = 0x01
ContextSpecific = 0x02
Private = 0x03
Asn1Tag* {.pure.} = enum
## Protobuf's field types enum
NoSupport,
Boolean,
Integer,
BitString,
OctetString,
Null,
Oid,
Sequence,
Context
Asn1Buffer* = object of RootObj
## ASN.1's message representation object
buffer*: seq[byte]
offset*: int
length*: int
Asn1Field* = object
klass*: Asn1Class
index*: int
offset*: int
length*: int
buffer*: seq[byte]
case kind*: Asn1Tag
of Asn1Tag.Boolean:
vbool*: bool
of Asn1Tag.Integer:
vint*: uint64
of Asn1Tag.BitString:
ubits*: int
else:
discard
Asn1Composite* = object of Asn1Buffer
tag*: Asn1Tag
idx*: int
const
Asn1OidSecp256r1* = [
0x2A'u8, 0x86'u8, 0x48'u8, 0xCE'u8, 0x3D'u8, 0x03'u8, 0x01'u8, 0x07'u8
]
## Encoded OID for `secp256r1` curve (1.2.840.10045.3.1.7)
Asn1OidSecp384r1* = [
0x2B'u8, 0x81'u8, 0x04'u8, 0x00'u8, 0x22'u8
]
## Encoded OID for `secp384r1` curve (1.3.132.0.34)
Asn1OidSecp521r1* = [
0x2B'u8, 0x81'u8, 0x04'u8, 0x00'u8, 0x23'u8
]
## Encoded OID for `secp521r1` curve (1.3.132.0.35)
Asn1OidSecp256k1* = [
0x2B'u8, 0x81'u8, 0x04'u8, 0x00'u8, 0x0A'u8
]
## Encoded OID for `secp256k1` curve (1.3.132.0.10)
Asn1OidEcPublicKey* = [
0x2A'u8, 0x86'u8, 0x48'u8, 0xCE'u8, 0x3D'u8, 0x02'u8, 0x01'u8
]
## Encoded OID for Elliptic Curve Public Key (1.2.840.10045.2.1)
Asn1OidRsaEncryption* = [
0x2A'u8, 0x86'u8, 0x48'u8, 0x86'u8, 0xF7'u8, 0x0D'u8, 0x01'u8,
0x01'u8, 0x01'u8
]
## Encoded OID for RSA Encryption (1.2.840.113549.1.1.1)
Asn1True* = [0x01'u8, 0x01'u8, 0xFF'u8]
## Encoded boolean ``TRUE``.
Asn1False* = [0x01'u8, 0x01'u8, 0x00'u8]
## Encoded boolean ``FALSE``.
Asn1Null* = [0x05'u8, 0x00'u8]
## Encoded ``NULL`` value.
template toOpenArray*(ab: Asn1Buffer): untyped =
toOpenArray(ab.buffer, ab.offset, ab.buffer.high)
template toOpenArray*(ac: Asn1Composite): untyped =
toOpenArray(ac.buffer, ac.offset, ac.buffer.high)
template toOpenArray*(af: Asn1Field): untyped =
toOpenArray(af.buffer, af.offset, af.offset + af.length - 1)
template isEmpty*(ab: Asn1Buffer): bool =
ab.offset >= len(ab.buffer)
template isEnough*(ab: Asn1Buffer, length: int): bool =
len(ab.buffer) >= ab.offset + length
proc len*[T: Asn1Buffer|Asn1Composite](abc: T): int {.inline.} =
len(abc.buffer) - abc.offset
proc len*(field: Asn1Field): int {.inline.} =
field.length
template getPtr*(field: untyped): pointer =
cast[pointer](unsafeAddr field.buffer[field.offset])
proc extend*[T: Asn1Buffer|Asn1Composite](abc: var T, length: int) {.inline.} =
## Extend buffer or composite's internal buffer by ``length`` octets.
abc.buffer.setLen(len(abc.buffer) + length)
proc code*(tag: Asn1Tag): byte {.inline.} =
## Converts Nim ``tag`` enum to ASN.1 tag code.
case tag:
of Asn1Tag.NoSupport:
0x00'u8
of Asn1Tag.Boolean:
0x01'u8
of Asn1Tag.Integer:
0x02'u8
of Asn1Tag.BitString:
0x03'u8
of Asn1Tag.OctetString:
0x04'u8
of Asn1Tag.Null:
0x05'u8
of Asn1Tag.Oid:
0x06'u8
of Asn1Tag.Sequence:
0x30'u8
of Asn1Tag.Context:
0xA0'u8
proc asn1EncodeLength*(dest: var openArray[byte], length: uint64): int =
## Encode ASN.1 DER length part of TLV triple and return number of bytes
## (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``length`` value, then result of encoding WILL NOT BE stored in ``dest``
## but number of bytes (octets) required will be returned.
if length < 0x80'u64:
if len(dest) >= 1:
dest[0] = byte(length and 0x7F'u64)
1
else:
var res = 1'u64
var z = length
while z != 0:
inc(res)
z = z shr 8
if uint64(len(dest)) >= res:
dest[0] = byte((0x80'u64 + (res - 1'u64)) and 0xFF)
var o = 1
for j in countdown(res - 2, 0):
dest[o] = byte((length shr (j shl 3)) and 0xFF'u64)
inc(o)
# Because our `length` argument is `uint64`, `res` could not be bigger
# then 9, so it is safe to convert it to `int`.
int(res)
proc asn1EncodeInteger*(dest: var openArray[byte],
value: openArray[byte]): int =
## Encode big-endian binary representation of integer as ASN.1 DER `INTEGER`
## and return number of bytes (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding WILL NOT BE stored in ``dest``
## but number of bytes (octets) required will be returned.
var buffer: array[16, byte]
var lenlen = 0
let offset =
block:
var o = 0
for i in 0 ..< len(value):
if value[o] != 0x00:
break
inc(o)
if o < len(value):
o
else:
o - 1
let destlen =
if len(value) > 0:
if value[offset] >= 0x80'u8:
lenlen = asn1EncodeLength(buffer, uint64(len(value) - offset + 1))
1 + lenlen + 1 + (len(value) - offset)
else:
lenlen = asn1EncodeLength(buffer, uint64(len(value) - offset))
1 + lenlen + (len(value) - offset)
else:
2
if len(dest) >= destlen:
var shift = 1
dest[0] = Asn1Tag.Integer.code()
copyMem(addr dest[1], addr buffer[0], lenlen)
# If ``destlen > 2`` it means that ``len(value) > 0`` too.
if destlen > 2:
if value[offset] >= 0x80'u8:
dest[1 + lenlen] = 0x00'u8
shift = 2
copyMem(addr dest[shift + lenlen], unsafeAddr value[offset],
len(value) - offset)
destlen
proc asn1EncodeInteger*[T: SomeUnsignedInt](dest: var openArray[byte],
value: T): int =
## Encode Nim's unsigned integer as ASN.1 DER `INTEGER` and return number of
## bytes (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
dest.asn1EncodeInteger(value.toBytesBE())
proc asn1EncodeBoolean*(dest: var openArray[byte], value: bool): int =
## Encode Nim's boolean as ASN.1 DER `BOOLEAN` and return number of bytes
## (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
let res = 3
if len(dest) >= res:
dest[0] = Asn1Tag.Boolean.code()
dest[1] = 0x01'u8
dest[2] = if value: 0xFF'u8 else: 0x00'u8
res
proc asn1EncodeNull*(dest: var openArray[byte]): int =
## Encode ASN.1 DER `NULL` and return number of bytes (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
let res = 2
if len(dest) >= res:
dest[0] = Asn1Tag.Null.code()
dest[1] = 0x00'u8
res
proc asn1EncodeOctetString*(dest: var openArray[byte],
value: openArray[byte]): int =
## Encode array of bytes as ASN.1 DER `OCTET STRING` and return number of
## bytes (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
var buffer: array[16, byte]
let lenlen = asn1EncodeLength(buffer, uint64(len(value)))
let res = 1 + lenlen + len(value)
if len(dest) >= res:
dest[0] = Asn1Tag.OctetString.code()
copyMem(addr dest[1], addr buffer[0], lenlen)
if len(value) > 0:
copyMem(addr dest[1 + lenlen], unsafeAddr value[0], len(value))
res
proc asn1EncodeBitString*(dest: var openArray[byte],
value: openArray[byte], bits = 0): int =
## Encode array of bytes as ASN.1 DER `BIT STRING` and return number of bytes
## (octets) used.
##
## ``bits`` number of unused bits in ``value``. If ``bits == 0``, all the bits
## from ``value`` will be used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
var buffer: array[16, byte]
let bitlen =
if bits != 0:
(len(value) shl 3) - bits
else:
(len(value) shl 3)
# Number of bytes used
let bytelen = (bitlen + 7) shr 3
# Number of unused bits
let unused = (8 - (bitlen and 7)) and 7
let mask = not((1'u8 shl unused) - 1'u8)
var lenlen = asn1EncodeLength(buffer, uint64(bytelen + 1))
let res = 1 + lenlen + 1 + len(value)
if len(dest) >= res:
dest[0] = Asn1Tag.BitString.code()
copyMem(addr dest[1], addr buffer[0], lenlen)
dest[1 + lenlen] = byte(unused)
if bytelen > 0:
let lastbyte = value[bytelen - 1]
copyMem(addr dest[2 + lenlen], unsafeAddr value[0], bytelen)
# Set unused bits to zero
dest[2 + lenlen + bytelen - 1] = lastbyte and mask
res
proc asn1EncodeTag[T: SomeUnsignedInt](dest: var openArray[byte],
value: T): int =
var v = value
if value <= cast[T](0x7F):
if len(dest) >= 1:
dest[0] = cast[byte](value)
1
else:
var s = 0
var res = 0
while v != 0:
v = v shr 7
s += 7
inc(res)
if len(dest) >= res:
var k = 0
while s != 0:
s -= 7
dest[k] = cast[byte](((value shr s) and cast[T](0x7F)) or cast[T](0x80))
inc(k)
dest[k - 1] = dest[k - 1] and 0x7F'u8
res
proc asn1EncodeOid*(dest: var openArray[byte], value: openArray[int]): int =
## Encode array of integers ``value`` as ASN.1 DER `OBJECT IDENTIFIER` and
## return number of bytes (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
var buffer: array[16, byte]
var res = 1
var oidlen = 1
for i in 2..<len(value):
oidlen += asn1EncodeTag(buffer, cast[uint64](value[i]))
res += asn1EncodeLength(buffer, uint64(oidlen))
res += oidlen
if len(dest) >= res:
let last = dest.high
var offset = 1
dest[0] = Asn1Tag.Oid.code()
offset += asn1EncodeLength(dest.toOpenArray(offset, last), uint64(oidlen))
dest[offset] = cast[byte](value[0] * 40 + value[1])
offset += 1
for i in 2..<len(value):
offset += asn1EncodeTag(dest.toOpenArray(offset, last),
cast[uint64](value[i]))
res
proc asn1EncodeOid*(dest: var openArray[byte], value: openArray[byte]): int =
## Encode array of bytes ``value`` as ASN.1 DER `OBJECT IDENTIFIER` and return
## number of bytes (octets) used.
##
## This procedure is useful to encode constant predefined identifiers such
## as ``asn1OidSecp256r1``, ``asn1OidRsaEncryption``.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
var buffer: array[16, byte]
let lenlen = asn1EncodeLength(buffer, uint64(len(value)))
let res = 1 + lenlen + len(value)
if len(dest) >= res:
dest[0] = Asn1Tag.Oid.code()
copyMem(addr dest[1], addr buffer[0], lenlen)
copyMem(addr dest[1 + lenlen], unsafeAddr value[0], len(value))
res
proc asn1EncodeSequence*(dest: var openArray[byte],
value: openArray[byte]): int =
## Encode ``value`` as ASN.1 DER `SEQUENCE` and return number of bytes
## (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
var buffer: array[16, byte]
let lenlen = asn1EncodeLength(buffer, uint64(len(value)))
let res = 1 + lenlen + len(value)
if len(dest) >= res:
dest[0] = Asn1Tag.Sequence.code()
copyMem(addr dest[1], addr buffer[0], lenlen)
copyMem(addr dest[1 + lenlen], unsafeAddr value[0], len(value))
res
proc asn1EncodeComposite*(dest: var openArray[byte],
value: Asn1Composite): int =
## Encode composite value and return number of bytes (octets) used.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
var buffer: array[16, byte]
let lenlen = asn1EncodeLength(buffer, uint64(len(value.buffer)))
let res = 1 + lenlen + len(value.buffer)
if len(dest) >= res:
dest[0] = value.tag.code()
copyMem(addr dest[1], addr buffer[0], lenlen)
copyMem(addr dest[1 + lenlen], unsafeAddr value.buffer[0],
len(value.buffer))
res
proc asn1EncodeContextTag*(dest: var openArray[byte], value: openArray[byte],
tag: int): int =
## Encode ASN.1 DER `CONTEXT SPECIFIC TAG` ``tag`` for value ``value`` and
## return number of bytes (octets) used.
##
## Note: Only values in [0, 15] range can be used as context tag ``tag``
## values.
##
## If length of ``dest`` is less then number of required bytes to encode
## ``value``, then result of encoding will not be stored in ``dest``
## but number of bytes (octets) required will be returned.
var buffer: array[16, byte]
let lenlen = asn1EncodeLength(buffer, uint64(len(value)))
let res = 1 + lenlen + len(value)
if len(dest) >= res:
dest[0] = 0xA0'u8 or (byte(tag and 0xFF) and 0x0F'u8)
copyMem(addr dest[1], addr buffer[0], lenlen)
copyMem(addr dest[1 + lenlen], unsafeAddr value[0], len(value))
res
proc getLength(ab: var Asn1Buffer): Asn1Result[uint64] =
## Decode length part of ASN.1 TLV triplet.
if not ab.isEmpty():
let b = ab.buffer[ab.offset]
if (b and 0x80'u8) == 0x00'u8:
let length = cast[uint64](b)
ab.offset += 1
return ok(length)
if b == 0x80'u8:
return err(Asn1Error.Indefinite)
if b == 0xFF'u8:
return err(Asn1Error.Incorrect)
let octets = cast[uint64](b and 0x7F'u8)
if octets > 8'u64:
return err(Asn1Error.Overflow)
if ab.isEnough(int(octets)):
var length: uint64 = 0
for i in 0..<int(octets):
length = (length shl 8) or cast[uint64](ab.buffer[ab.offset + i + 1])
ab.offset = ab.offset + int(octets) + 1
return ok(length)
else:
return err(Asn1Error.Incomplete)
else:
return err(Asn1Error.Incomplete)
proc getTag(ab: var Asn1Buffer, tag: var int): Asn1Result[Asn1Class] =
## Decode tag part of ASN.1 TLV triplet.
if not ab.isEmpty():
let
b = ab.buffer[ab.offset]
c = int((b and 0xC0'u8) shr 6)
tag = int(b and 0x3F)
ab.offset += 1
if c >= 0 and c < 4:
ok(cast[Asn1Class](c))
else:
err(Asn1Error.Incorrect)
else:
err(Asn1Error.Incomplete)
proc read*(ab: var Asn1Buffer): Asn1Result[Asn1Field] =
## Decode value part of ASN.1 TLV triplet.
var
field: Asn1Field
tag, ttag, offset: int
length, tlength: uint64
aclass: Asn1Class
inclass: bool
inclass = false
while true:
offset = ab.offset
aclass = ? ab.getTag(tag)
case aclass
of Asn1Class.ContextSpecific:
if inclass:
return err(Asn1Error.Incorrect)
else:
inclass = true
ttag = tag
tlength = ? ab.getLength()
of Asn1Class.Universal:
length = ? ab.getLength()
if inclass:
if length >= tlength:
return err(Asn1Error.Incorrect)
case byte(tag)
of Asn1Tag.Boolean.code():
# BOOLEAN
if length != 1:
return err(Asn1Error.Incorrect)
if not ab.isEnough(int(length)):
return err(Asn1Error.Incomplete)
let b = ab.buffer[ab.offset]
if b != 0xFF'u8 and b != 0x00'u8:
return err(Asn1Error.Incorrect)
field = Asn1Field(kind: Asn1Tag.Boolean, klass: aclass,
index: ttag, offset: int(ab.offset),
length: 1)
shallowCopy(field.buffer, ab.buffer)
field.vbool = (b == 0xFF'u8)
ab.offset += 1
return ok(field)
of Asn1Tag.Integer.code():
# INTEGER
if length == 0:
return err(Asn1Error.Incorrect)
if not ab.isEnough(int(length)):
return err(Asn1Error.Incomplete)
# Count number of leading zeroes
var zc = 0
while (zc < int(length)) and (ab.buffer[ab.offset + zc] == 0x00'u8):
inc(zc)
if zc > 1:
return err(Asn1Error.Incorrect)
if zc == 0:
# Negative or Positive integer
field = Asn1Field(kind: Asn1Tag.Integer, klass: aclass,
index: ttag, offset: int(ab.offset),
length: int(length))
shallowCopy(field.buffer, ab.buffer)
if (ab.buffer[ab.offset] and 0x80'u8) == 0x80'u8:
# Negative integer
if length <= 8:
# We need this transformation because our field.vint is uint64.
for i in 0 ..< 8:
if i < 8 - int(length):
field.vint = (field.vint shl 8) or 0xFF'u64
else:
let offset = ab.offset + i - (8 - int(length))
field.vint = (field.vint shl 8) or uint64(ab.buffer[offset])
else:
# Positive integer
if length <= 8:
for i in 0 ..< int(length):
field.vint = (field.vint shl 8) or
uint64(ab.buffer[ab.offset + i])
ab.offset += int(length)
return ok(field)
else:
if length == 1:
# Zero value integer
field = Asn1Field(kind: Asn1Tag.Integer, klass: aclass,
index: ttag, offset: int(ab.offset),
length: int(length), vint: 0'u64)
shallowCopy(field.buffer, ab.buffer)
ab.offset += int(length)
return ok(field)
else:
# Positive integer with leading zero
field = Asn1Field(kind: Asn1Tag.Integer, klass: aclass,
index: ttag, offset: int(ab.offset) + 1,
length: int(length) - 1)
shallowCopy(field.buffer, ab.buffer)
if length <= 9:
for i in 1 ..< int(length):
field.vint = (field.vint shl 8) or
uint64(ab.buffer[ab.offset + i])
ab.offset += int(length)
return ok(field)
of Asn1Tag.BitString.code():
# BIT STRING
if length == 0:
# BIT STRING should include `unused` bits field, so length should be
# bigger then 1.
return err(Asn1Error.Incorrect)
elif length == 1:
if ab.buffer[ab.offset] != 0x00'u8:
return err(Asn1Error.Incorrect)
else:
# Zero-length BIT STRING.
field = Asn1Field(kind: Asn1Tag.BitString, klass: aclass,
index: ttag, offset: int(ab.offset + 1),
length: 0, ubits: 0)
shallowCopy(field.buffer, ab.buffer)
ab.offset += int(length)
return ok(field)
else:
if not ab.isEnough(int(length)):
return err(Asn1Error.Incomplete)
let unused = ab.buffer[ab.offset]
if unused > 0x07'u8:
# Number of unused bits should not be bigger then `7`.
return err(Asn1Error.Incorrect)
let mask = (1'u8 shl int(unused)) - 1'u8
if (ab.buffer[ab.offset + int(length) - 1] and mask) != 0x00'u8:
## All unused bits should be set to `0`.
return err(Asn1Error.Incorrect)
field = Asn1Field(kind: Asn1Tag.BitString, klass: aclass,
index: ttag, offset: int(ab.offset + 1),
length: int(length - 1), ubits: int(unused))
shallowCopy(field.buffer, ab.buffer)
ab.offset += int(length)
return ok(field)
of Asn1Tag.OctetString.code():
# OCTET STRING
if not ab.isEnough(int(length)):
return err(Asn1Error.Incomplete)
field = Asn1Field(kind: Asn1Tag.OctetString, klass: aclass,
index: ttag, offset: int(ab.offset),
length: int(length))
shallowCopy(field.buffer, ab.buffer)
ab.offset += int(length)
return ok(field)
of Asn1Tag.Null.code():
# NULL
if length != 0:
return err(Asn1Error.Incorrect)
field = Asn1Field(kind: Asn1Tag.Null, klass: aclass, index: ttag,
offset: int(ab.offset), length: 0)
shallowCopy(field.buffer, ab.buffer)
ab.offset += int(length)
return ok(field)
of Asn1Tag.Oid.code():
# OID
if not ab.isEnough(int(length)):
return err(Asn1Error.Incomplete)
field = Asn1Field(kind: Asn1Tag.Oid, klass: aclass,
index: ttag, offset: int(ab.offset),
length: int(length))
shallowCopy(field.buffer, ab.buffer)
ab.offset += int(length)
return ok(field)
of Asn1Tag.Sequence.code():
# SEQUENCE
if not ab.isEnough(int(length)):
return err(Asn1Error.Incomplete)
field = Asn1Field(kind: Asn1Tag.Sequence, klass: aclass,
index: ttag, offset: int(ab.offset),
length: int(length))
shallowCopy(field.buffer, ab.buffer)
ab.offset += int(length)
return ok(field)
else:
return err(Asn1Error.NoSupport)
inclass = false
ttag = 0
else:
return err(Asn1Error.NoSupport)
proc getBuffer*(field: Asn1Field): Asn1Buffer {.inline.} =
## Return ``field`` as Asn1Buffer to enter composite types.
Asn1Buffer(buffer: field.buffer, offset: field.offset, length: field.length)
proc `==`*(field: Asn1Field, data: openArray[byte]): bool =
## Compares field ``field`` data with ``data`` and returns ``true`` if both
## buffers are equal.
let length = len(field.buffer)
if length == 0 and len(data) == 0:
true
else:
if length > 0:
if field.length == len(data):
CT.isEqual(
field.buffer.toOpenArray(field.offset,
field.offset + field.length - 1),
data.toOpenArray(0, field.length - 1))
else:
false
else:
false
proc init*(t: typedesc[Asn1Buffer], data: openArray[byte]): Asn1Buffer =
## Initialize ``Asn1Buffer`` from array of bytes ``data``.
Asn1Buffer(buffer: @data)
proc init*(t: typedesc[Asn1Buffer], data: string): Asn1Buffer =
## Initialize ``Asn1Buffer`` from hexadecimal string ``data``.
Asn1Buffer(buffer: ncrutils.fromHex(data))
proc init*(t: typedesc[Asn1Buffer]): Asn1Buffer =
## Initialize empty ``Asn1Buffer``.
Asn1Buffer(buffer: newSeq[byte]())
proc init*(t: typedesc[Asn1Composite], tag: Asn1Tag): Asn1Composite =
## Initialize ``Asn1Composite`` with tag ``tag``.
Asn1Composite(tag: tag, buffer: newSeq[byte]())
proc init*(t: typedesc[Asn1Composite], idx: int): Asn1Composite =
## Initialize ``Asn1Composite`` with tag context-specific id ``id``.
Asn1Composite(tag: Asn1Tag.Context, idx: idx, buffer: newSeq[byte]())
proc `$`*(buffer: Asn1Buffer): string =
## Return string representation of ``buffer``.
ncrutils.toHex(buffer.toOpenArray())
proc `$`*(field: Asn1Field): string =
## Return string representation of ``field``.
var res = "["
res.add($field.kind)
res.add("]")
case field.kind
of Asn1Tag.Boolean:
res.add(" ")
res.add($field.vbool)
res
of Asn1Tag.Integer:
res.add(" ")
if field.length <= 8:
res.add($field.vint)
else:
res.add(ncrutils.toHex(field.toOpenArray()))
res
of Asn1Tag.BitString:
res.add(" ")
res.add("(")
res.add($field.ubits)
res.add(" bits) ")
res.add(ncrutils.toHex(field.toOpenArray()))
res
of Asn1Tag.OctetString:
res.add(" ")
res.add(ncrutils.toHex(field.toOpenArray()))
res
of Asn1Tag.Null:
res.add(" NULL")
res
of Asn1Tag.Oid:
res.add(" ")
res.add(ncrutils.toHex(field.toOpenArray()))
res
of Asn1Tag.Sequence:
res.add(" ")
res.add(ncrutils.toHex(field.toOpenArray()))
res
of Asn1Tag.Context:
res.add(" ")
res.add(ncrutils.toHex(field.toOpenArray()))
res
else:
res.add(" ")
res.add(ncrutils.toHex(field.toOpenArray()))
res
proc write*[T: Asn1Buffer|Asn1Composite](abc: var T, tag: Asn1Tag) =
## Write empty value to buffer or composite with ``tag``.
##
## This procedure must be used to write `NULL`, `0` or empty `BIT STRING`,
## `OCTET STRING` types.
doAssert(tag in {Asn1Tag.Null, Asn1Tag.Integer, Asn1Tag.BitString,
Asn1Tag.OctetString})
var length: int
if tag == Asn1Tag.Null:
length = asn1EncodeNull(abc.toOpenArray())
abc.extend(length)
discard asn1EncodeNull(abc.toOpenArray())
elif tag == Asn1Tag.Integer:
length = asn1EncodeInteger(abc.toOpenArray(), 0'u64)
abc.extend(length)
discard asn1EncodeInteger(abc.toOpenArray(), 0'u64)
elif tag == Asn1Tag.BitString:
var tmp: array[1, byte]
length = asn1EncodeBitString(abc.toOpenArray(), tmp.toOpenArray(0, -1))
abc.extend(length)
discard asn1EncodeBitString(abc.toOpenArray(), tmp.toOpenArray(0, -1))
elif tag == Asn1Tag.OctetString:
var tmp: array[1, byte]
length = asn1EncodeOctetString(abc.toOpenArray(), tmp.toOpenArray(0, -1))
abc.extend(length)
discard asn1EncodeOctetString(abc.toOpenArray(), tmp.toOpenArray(0, -1))
abc.offset += length
proc write*[T: Asn1Buffer|Asn1Composite](abc: var T, value: uint64) =
## Write uint64 ``value`` to buffer or composite as ASN.1 `INTEGER`.
let length = asn1EncodeInteger(abc.toOpenArray(), value)
abc.extend(length)
discard asn1EncodeInteger(abc.toOpenArray(), value)
abc.offset += length
proc write*[T: Asn1Buffer|Asn1Composite](abc: var T, value: bool) =
## Write bool ``value`` to buffer or composite as ASN.1 `BOOLEAN`.
let length = asn1EncodeBoolean(abc.toOpenArray(), value)
abc.extend(length)
discard asn1EncodeBoolean(abc.toOpenArray(), value)
abc.offset += length
proc write*[T: Asn1Buffer|Asn1Composite](abc: var T, tag: Asn1Tag,
value: openArray[byte], bits = 0) =
## Write array ``value`` using ``tag``.
##
## This procedure is used to write ASN.1 `INTEGER`, `OCTET STRING`,
## `BIT STRING` or `OBJECT IDENTIFIER`.
##
## For `BIT STRING` you can use ``bits`` argument to specify number of used
## bits.
doAssert(tag in {Asn1Tag.Integer, Asn1Tag.OctetString, Asn1Tag.BitString,
Asn1Tag.Oid})
var length: int
if tag == Asn1Tag.Integer:
length = asn1EncodeInteger(abc.toOpenArray(), value)
abc.extend(length)
discard asn1EncodeInteger(abc.toOpenArray(), value)
elif tag == Asn1Tag.OctetString:
length = asn1EncodeOctetString(abc.toOpenArray(), value)
abc.extend(length)
discard asn1EncodeOctetString(abc.toOpenArray(), value)
elif tag == Asn1Tag.BitString:
length = asn1EncodeBitString(abc.toOpenArray(), value, bits)
abc.extend(length)
discard asn1EncodeBitString(abc.toOpenArray(), value, bits)
elif tag == Asn1Tag.Oid:
length = asn1EncodeOid(abc.toOpenArray(), value)
abc.extend(length)
discard asn1EncodeOid(abc.toOpenArray(), value)
abc.offset += length
proc write*[T: Asn1Buffer|Asn1Composite](abc: var T, value: Asn1Composite) =
doAssert(len(value) > 0, "Composite value not finished")
var length: int
if value.tag == Asn1Tag.Sequence:
length = asn1EncodeSequence(abc.toOpenArray(), value.buffer)
abc.extend(length)
discard asn1EncodeSequence(abc.toOpenArray(), value.buffer)
elif value.tag == Asn1Tag.BitString:
length = asn1EncodeBitString(abc.toOpenArray(), value.buffer)
abc.extend(length)
discard asn1EncodeBitString(abc.toOpenArray(), value.buffer)
elif value.tag == Asn1Tag.Context:
length = asn1EncodeContextTag(abc.toOpenArray(), value.buffer, value.idx)
abc.extend(length)
discard asn1EncodeContextTag(abc.toOpenArray(), value.buffer, value.idx)
abc.offset += length
proc finish*[T: Asn1Buffer|Asn1Composite](abc: var T) {.inline.} =
## Finishes buffer or composite and prepares it for writing.
abc.offset = 0
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