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value.go
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value.go
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package ber
import (
"encoding/asn1"
"fmt"
"math/big"
"time"
)
func (v *Token) mustBeValue() {
if v.Kind != Value {
panic(fmt.Sprintf("invalid call on non-kind: %#v", v))
}
}
func (v *Token) Universal() (ret interface{}, err error) {
v.mustBeValue()
if v.Class != Universal {
err = SyntaxError{"not an universal value"}
return
}
switch v.Tag {
case TagBool:
ret, err = v.AsBool()
case TagInteger:
ret, err = v.AsBigInt()
case TagBitString:
ret, err = v.AsBitString()
case TagOctetString:
ret, err = v.AsOctetString()
case TagNULL:
ret = struct{}{}
case TagObjectIdentifier:
ret, err = v.AsObjectIdentifier()
// case TagObjectDescriptor:
// case TagExternal:
// case TagRealFloat:
case TagEnumerated:
ret, err = v.AsInt64()
// case TagEmbeddedPDV:
case TagUTF8String:
ret, err = v.AsUTF8String()
// case TagRelativeOID:
// case TagSequence:
// case TagSet:
case TagNumericString:
ret, err = v.AsNumericString()
case TagPrintableString:
ret, err = v.AsPrintableString()
case TagT61String:
ret, err = v.AsT61String()
// case TagVideotexString:
case TagIA5String:
ret, err = v.AsIA5String()
case TagUTCTime:
ret, err = v.AsUTCTime()
case TagGeneralizedTime:
ret, err = v.AsGeneralizedTime()
//case TagGraphicString:
case TagVisibleString:
ret, err = v.AsVisibleString()
case TagGeneralString:
ret, err = v.AsUTF8String()
case TagUniversalString:
ret, err = v.AsUTF8String()
case TagCharacterString:
ret, err = v.AsUTF8String()
//case TagBMPString:
default:
err = unimplementedType
}
return
}
// BOOLEAN
func (v *Token) AsBool() (ret bool, err error) {
v.mustBeValue()
bytes := v.Bytes
if len(bytes) != 1 {
err = SyntaxError{"invalid boolean"}
return
}
// DER demands that "If the encoding represents the boolean value TRUE,
// its single contents octet shall have all eight bits set to one."
// Thus only 0 and 255 are valid encoded values.
switch bytes[0] {
case 0:
ret = false
case 1:
ret = true
default:
err = SyntaxError{"invalid boolean"}
}
return
}
// INTEGER
// AsInt64 treats the given bytes as a big-endian, signed integer and
// returns the result.
func (v *Token) AsInt64() (ret int64, err error) {
v.mustBeValue()
bytes := v.Bytes
if len(bytes) > 8 {
// We'll overflow an int64 in this case.
err = StructuralError{"integer too large"}
return
}
for bytesRead := 0; bytesRead < len(bytes); bytesRead++ {
ret <<= 8
ret |= int64(bytes[bytesRead])
}
// Shift up and down in order to sign extend the result.
ret <<= 64 - uint8(len(bytes))*8
ret >>= 64 - uint8(len(bytes))*8
return
}
// AsInt32 treats the given bytes as a big-endian, signed integer and returns
// the result.
func (v *Token) AsInt32() (ret int32, err error) {
v.mustBeValue()
ret64, err := v.AsInt64()
if err != nil {
return 0, err
}
if ret64 != int64(int32(ret64)) {
return 0, StructuralError{"integer too large"}
}
return int32(ret64), nil
}
var bigOne = big.NewInt(1)
// parseBigInt treats the given bytes as a big-endian, signed integer and returns
// the result.
func (v *Token) AsBigInt() (*big.Int, error) {
v.mustBeValue()
bytes := v.Bytes
ret := new(big.Int)
if len(bytes) > 0 && bytes[0]&0x80 == 0x80 {
// This is a negative number.
notBytes := make([]byte, len(bytes))
for i := range notBytes {
notBytes[i] = ^bytes[i]
}
ret.SetBytes(notBytes)
ret.Add(ret, bigOne)
ret.Neg(ret)
return ret, nil
}
ret.SetBytes(bytes)
return ret, nil
}
// BIT STRING
// AsBitString parses an ASN.1 bit string from the given byte slice and returns it.
func (v *Token) AsBitString() (ret asn1.BitString, err error) {
v.mustBeValue()
bytes := v.Bytes
if len(bytes) == 0 {
err = SyntaxError{"zero length BIT STRING"}
return
}
paddingBits := int(bytes[0])
if paddingBits > 7 ||
len(bytes) == 1 && paddingBits > 0 {
err = SyntaxError{"invalid padding bits in BIT STRING"}
return
}
ret.BitLength = (len(bytes)-1)*8 - paddingBits
ret.Bytes = bytes[1:]
// remove the padding bits
last := len(ret.Bytes) - 1
ret.Bytes[last] = (ret.Bytes[last] >> uint(paddingBits)) << uint(paddingBits)
return
}
func (v *Token) AsOctetString() (ret []byte, err error) {
v.mustBeValue()
return v.Bytes, nil
}
// AsObjectIdentifier parses an OBJECT IDENTIFIER from the given bytes and
// returns it. An object identifier is a sequence of variable length integers
// that are assigned in a hierarchy.
func (val *Token) AsObjectIdentifier() (s asn1.ObjectIdentifier, err error) {
val.mustBeValue()
bytes := val.Bytes
if len(bytes) == 0 {
err = SyntaxError{"zero length OBJECT IDENTIFIER"}
return
}
// In the worst case, we get two elements from the first byte (which is
// encoded differently) and then every varint is a single byte long.
s = make(asn1.ObjectIdentifier, len(bytes)+1)
// The first varint is 40*Token1 + value2:
// According to this packing, value1 can take the values 0, 1 and 2 only.
// When value1 = 0 or value1 = 1, then value2 is <= 39. When value1 = 2,
// then there are no restrictions on value2.
v, offset, err := parseBase128Int(bytes, 0)
if err != nil {
return
}
if v < 80 {
s[0] = v / 40
s[1] = v % 40
} else {
s[0] = 2
s[1] = v - 80
}
i := 2
for ; offset < len(bytes); i++ {
v, offset, err = parseBase128Int(bytes, offset)
if err != nil {
return
}
s[i] = v
}
s = s[0:i]
return
}
// UTCTime
func (v *Token) AsUTCTime() (ret time.Time, err error) {
v.mustBeValue()
s := string(v.Bytes)
ret, err = time.Parse("0601021504Z0700", s)
if err != nil {
ret, err = time.Parse("060102150405Z0700", s)
}
if err == nil && ret.Year() >= 2050 {
// UTCTime only encodes times prior to 2050. See https://tools.ietf.org/html/rfc5280#section-4.1.2.5.1
ret = ret.AddDate(-100, 0, 0)
}
return
}
// AsGeneralizedTime parses the GeneralizedTime from the given byte slice
// and returns the resulting time.
func (v *Token) AsGeneralizedTime() (ret time.Time, err error) {
v.mustBeValue()
return time.Parse("20060102150405Z0700", string(v.Bytes))
}
// NumericString
func (v *Token) AsNumericString() (ret string, err error) {
v.mustBeValue()
bytes := v.Bytes
for _, b := range bytes {
if !isNumeric(b) {
err = SyntaxError{"NumericString contains invalid character"}
return
}
}
ret = string(bytes)
return
}
// isNumeric returns true iff the given b is in the ASN.1 NumericString set.
func isNumeric(b byte) bool {
return '0' <= b && b <= '9' || b == ' '
}
// AsPrintableString parses a ASN.1 PrintableString from the given byte
// array and returns it.
func (v *Token) AsPrintableString() (ret string, err error) {
v.mustBeValue()
bytes := v.Bytes
for _, b := range bytes {
if !isPrintable(b) {
err = SyntaxError{"PrintableString contains invalid character"}
return
}
}
ret = string(bytes)
return
}
// isPrintable returns true iff the given b is in the ASN.1 PrintableString set.
func isPrintable(b byte) bool {
return 'a' <= b && b <= 'z' ||
'A' <= b && b <= 'Z' ||
'0' <= b && b <= '9' ||
'\'' <= b && b <= ')' ||
'+' <= b && b <= '/' ||
b == ' ' ||
b == ':' ||
b == '=' ||
b == '?' ||
// This is technically not allowed in a PrintableString.
// However, x509 certificates with wildcard strings don't
// always use the correct string type so we permit it.
b == '*'
}
// VisibleString
// AsVisibleString parses a ASN.1 VisibleString from the given byte
// array and returns it.
func (v *Token) AsVisibleString() (ret string, err error) {
v.mustBeValue()
bytes := v.Bytes
for _, b := range bytes {
if b < 0x20 {
err = SyntaxError{"VisibleString contains invalid character"}
return
}
}
ret = string(bytes)
return
}
// IA5String
// parseIA5String parses a ASN.1 IA5String (ASCII string) from the given
// byte slice and returns it.
func (v *Token) AsIA5String() (ret string, err error) {
v.mustBeValue()
bytes := v.Bytes
for _, b := range bytes {
if b >= 0x80 {
err = SyntaxError{"IA5String contains invalid character"}
return
}
}
ret = string(bytes)
return
}
// T61String
// parseT61String parses a ASN.1 T61String (8-bit clean string) from the given
// byte slice and returns it.
func (v *Token) AsT61String() (ret string, err error) {
v.mustBeValue()
return string(v.Bytes), nil
}
// UTF8String
// parseUTF8String parses a ASN.1 UTF8String (raw UTF-8) from the given byte
// array and returns it.
func (v *Token) AsUTF8String() (ret string, err error) {
v.mustBeValue()
return string(v.Bytes), nil
}