mirror of
https://github.com/wader/fq.git
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8e0dde03d0
This will allow passing both cli options and format options to sub decoder. Ex: pass keylog option to a tls decoder when decoding a pcap. Ex: pass decode options to a format inside a http body inside a pcap. Add ArgAs method to lookup argument based on type. This also makes the format decode function have same signature as sub decoders in the decode API. This change decode.Format a bit: DecodeFn is now just func(d *D) any DecodeInArg renamed to DefaultInArg
420 lines
12 KiB
Go
420 lines
12 KiB
Go
package asn1
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// T-REC-X.690-200811 (BER, DER, CER)
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// https://www.itu.int/ITU-T/studygroups/com10/languages/X.690_1297.pdf
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// https://cdn.standards.iteh.ai/samples/12285/039296509e8b40f3b25ba025de60365d/ISO-6093-1985.pdf
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// https://en.wikipedia.org/wiki/X.690
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// https://letsencrypt.org/docs/a-warm-welcome-to-asn1-and-der/
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// https://luca.ntop.org/Teaching/Appunti/asn1.html
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// https://lapo.it/asn1js/
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// TODO: schema
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// TODO: der/cer via mode?
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// TODO: better torepr
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// TODO: utc time
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// TODO: validate CER DER
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// TODO: bigrat?
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import (
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"embed"
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"math"
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"strconv"
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"strings"
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"github.com/wader/fq/format"
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"github.com/wader/fq/pkg/bitio"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/interp"
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"github.com/wader/fq/pkg/scalar"
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)
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//go:embed asn1_ber.jq
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//go:embed asn1_ber.md
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var asn1FS embed.FS
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func init() {
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interp.RegisterFormat(decode.Format{
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Name: format.ASN1_BER,
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Description: "ASN1 BER (basic encoding rules, also CER and DER)",
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DecodeFn: decodeASN1BER,
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Functions: []string{"torepr"},
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})
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interp.RegisterFS(asn1FS)
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}
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const (
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classUniversal = 0b00
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classApplication = 0b01
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classContext = 0b10
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classPrivate = 0b11
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)
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var tagClassMap = scalar.UintMapSymStr{
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classUniversal: "universal",
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classApplication: "application",
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classContext: "context",
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classPrivate: "private",
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}
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const (
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formPrimitive = 0
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formConstructed = 1
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)
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var constructedPrimitiveMap = scalar.UintMapSymStr{
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formConstructed: "constructed",
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formPrimitive: "primitive",
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}
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const (
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universalTypeEndOfContent = 0x00
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universalTypeBoolean = 0x01
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universalTypeInteger = 0x02
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universalTypeBitString = 0x03
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universalTypeOctetString = 0x04
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universalTypeNull = 0x05
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universalTypeObjectIdentifier = 0x06
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universalTypeObjectDescriptor = 0x07 // not encoded, just documentation?
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universalTypeExternal = 0x08
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universalTypeReal = 0x09
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universalTypeEnumerated = 0x0a
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universalTypeEmbedded = 0x0b
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universalTypeUTF8string = 0x0c
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universalTypeSequence = 0x10
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universalTypeSet = 0x11
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universalTypeNumericString = 0x12
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universalTypePrintableString = 0x13
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universalTypeTeletexString = 0x14
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universalTypeVideotexString = 0x15
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universalTypeIA5String = 0x16
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universalTypeUTCTime = 0x17
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universalTypeGeneralizedtime = 0x18
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universalTypeGraphicString = 0x19 // not encoded?
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universalTypeVisibleString = 0x1a
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universalTypeGeneralString = 0x1b
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universalTypeUniversalString = 0x1c // not encoded?
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)
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var universalTypeMap = scalar.UintMapSymStr{
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universalTypeEndOfContent: "end_of_content",
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universalTypeBoolean: "boolean",
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universalTypeInteger: "integer",
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universalTypeBitString: "bit_string",
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universalTypeOctetString: "octet_string",
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universalTypeNull: "null",
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universalTypeObjectIdentifier: "object_identifier",
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universalTypeObjectDescriptor: "object_descriptor",
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universalTypeExternal: "external",
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universalTypeReal: "real",
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universalTypeEnumerated: "enumerated",
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universalTypeEmbedded: "embedded",
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universalTypeUTF8string: "utf8_string",
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universalTypeSequence: "sequence",
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universalTypeSet: "set",
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universalTypeNumericString: "numeric_string",
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universalTypePrintableString: "printable_string",
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universalTypeTeletexString: "teletex_string",
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universalTypeVideotexString: "videotex_string",
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universalTypeIA5String: "ia5_string",
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universalTypeUTCTime: "utc_time",
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universalTypeGeneralizedtime: "generalized_time",
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universalTypeGraphicString: "graphic_string",
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universalTypeVisibleString: "visible_string",
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universalTypeGeneralString: "general_string",
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universalTypeUniversalString: "universal_string",
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}
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const (
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lengthIndefinite = 0
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lengthEndMarker = 0x00_00
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)
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const (
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decimalPlusInfinity = 0b00_00_00
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decimalMinusInfinity = 0b00_00_01
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decimalNan = 0b00_00_10
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decimalMinusZero = 0b00_00_11
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)
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var lengthMap = scalar.UintMapSymStr{
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0: "indefinite",
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}
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func decodeLength(d *decode.D) uint64 {
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n := d.U8()
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if n&0b1000_0000 != 0 {
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n = n & 0b0111_1111
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if n == 0 {
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return lengthIndefinite
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}
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if n == 127 {
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d.Errorf("length 127 reserved")
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}
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// TODO: bigint
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return d.U(int(n) * 8)
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}
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return n & 0b0111_1111
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}
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// TODO: bigint?
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func decodeTagNumber(d *decode.D) uint64 {
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v := d.U5()
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moreBytes := v == 0b11111
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for moreBytes {
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moreBytes = d.Bool()
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v = v<<7 | d.U7()
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}
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return v
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}
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func decodeASN1BERValue(d *decode.D, bib *bitio.Buffer, sb *strings.Builder, parentForm uint64, parentTag uint64) {
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class := d.FieldU2("class", tagClassMap)
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form := d.FieldU1("form", constructedPrimitiveMap)
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// TODO: verify
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// TODO: constructed types verify
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_ = parentTag
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_ = parentForm
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var tag uint64
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switch class {
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case classUniversal:
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tag = d.FieldUintFn("tag", decodeTagNumber, universalTypeMap, scalar.UintHex)
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default:
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tag = d.FieldUintFn("tag", decodeTagNumber)
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}
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length := d.FieldUintFn("length", decodeLength, lengthMap)
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var l int64
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switch length {
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case lengthIndefinite:
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// null has zero length byte
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if !(class == classUniversal && tag == universalTypeNull) && form == formPrimitive {
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d.Fatalf("primitive with indefinite length")
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}
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l = d.BitsLeft()
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default:
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l = int64(length) * 8
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}
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d.LimitedFn(l, func(d *decode.D) {
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switch {
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case form == formConstructed || tag == universalTypeSequence || tag == universalTypeSet:
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d.FieldArray("constructed", func(d *decode.D) {
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for !d.End() {
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if length == lengthIndefinite && d.PeekBits(16) == lengthEndMarker {
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break
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}
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if form == formConstructed && bib == nil && sb == nil {
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switch tag {
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case universalTypeBitString:
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bib = &bitio.Buffer{}
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case universalTypeOctetString:
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bib = &bitio.Buffer{}
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case universalTypeUTF8string,
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universalTypeNumericString,
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universalTypePrintableString,
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universalTypeTeletexString,
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universalTypeVideotexString,
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universalTypeIA5String,
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universalTypeUTCTime,
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universalTypeVisibleString, // not encoded?
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universalTypeGeneralString: // not encoded?
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sb = &strings.Builder{}
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}
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}
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d.FieldStruct("object", func(d *decode.D) { decodeASN1BERValue(d, bib, sb, form, tag) })
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}
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})
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if length == lengthIndefinite {
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d.FieldU16("end_marker")
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}
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if form == formConstructed {
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switch tag {
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case universalTypeBitString:
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if bib != nil {
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buf, bufLen := bib.Bits()
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d.FieldRootBitBuf("value", bitio.NewBitReader(buf, bufLen))
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}
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case universalTypeOctetString:
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if bib != nil {
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buf, bufLen := bib.Bits()
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d.FieldRootBitBuf("value", bitio.NewBitReader(buf, bufLen))
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}
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case universalTypeUTF8string,
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universalTypeNumericString,
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universalTypePrintableString,
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universalTypeTeletexString,
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universalTypeVideotexString,
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universalTypeIA5String,
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universalTypeUTCTime,
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universalTypeVisibleString, // not encoded?
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universalTypeGeneralString: // not encoded?
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if sb != nil {
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d.FieldValueStr("value", sb.String())
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}
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}
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}
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case class == classUniversal && tag == universalTypeEndOfContent:
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// nop
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case class == classUniversal && tag == universalTypeBoolean:
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d.FieldU8("value", scalar.UintRangeToScalar{
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{Range: [2]uint64{0, 0}, S: scalar.Uint{Sym: false}},
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{Range: [2]uint64{0x01, 0xff1}, S: scalar.Uint{Sym: true}},
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})
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case class == classUniversal && tag == universalTypeInteger:
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if length > 8 {
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d.FieldSBigInt("value", int(length)*8)
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} else {
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d.FieldS("value", int(length)*8)
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}
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case class == classUniversal && tag == universalTypeBitString:
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unusedBitsCount := d.FieldU8("unused_bits_count")
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if unusedBitsCount > 7 {
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d.Fatalf("unusedBitsCount %d > 7", unusedBitsCount)
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}
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br := d.FieldRawLen("value", int64(length-1)*8-int64(unusedBitsCount))
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if bib != nil {
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// TODO: helper?
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if _, err := bitio.Copy(bib, br); err != nil {
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d.IOPanic(err, "bitio.Copy")
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}
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}
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if unusedBitsCount > 0 {
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d.FieldRawLen("unused_bits", int64(unusedBitsCount))
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}
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case class == classUniversal && tag == universalTypeOctetString:
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br := d.FieldRawLen("value", int64(length)*8)
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if bib != nil {
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// TODO: helper?
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if _, err := bitio.Copy(bib, br); err != nil {
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d.IOPanic(err, "bitio.Copy")
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}
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}
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case class == classUniversal && tag == universalTypeNull:
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d.FieldValueAny("value", nil)
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case class == classUniversal && tag == universalTypeObjectIdentifier:
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d.FieldArray("value", func(d *decode.D) {
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// first byte is = oid0*40 + oid1
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d.FieldUintFn("oid", func(d *decode.D) uint64 { return d.U8() / 40 })
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d.SeekRel(-8)
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d.FieldUintFn("oid", func(d *decode.D) uint64 { return d.U8() % 40 })
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for !d.End() {
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d.FieldUintFn("oid", func(d *decode.D) uint64 {
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more := true
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var n uint64
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for more {
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b := d.U8()
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n = n<<7 | b&0b0111_1111
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more = b&0b1000_0000 != 0
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}
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return n
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})
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}
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})
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case class == classUniversal && tag == universalTypeObjectDescriptor: // not encoded, just documentation?
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// nop
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case class == classUniversal && tag == universalTypeExternal:
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d.FieldRawLen("value", int64(length)*8)
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case class == classUniversal && tag == universalTypeReal:
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switch {
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case length == 0:
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d.FieldValueUint("value", 0)
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default:
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switch d.FieldBool("binary_encoding") {
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case true:
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s := d.FieldScalarBool("sign", scalar.BoolMapSymSint{
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true: -1,
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false: 1,
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}).SymSint()
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base := d.FieldScalarU2("base", scalar.UintMapSymUint{
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0b00: 2,
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0b01: 8,
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0b10: 16,
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0b11: 0,
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}).SymUint()
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scale := d.FieldU2("scale")
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format := d.FieldU2("format")
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var exp int64
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switch format {
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case 0b00:
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exp = d.FieldS8("exp")
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case 0b01:
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exp = d.FieldS16("exp")
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case 0b10:
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exp = d.FieldS24("exp")
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default:
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n := d.FieldU8("exp_bytes")
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// TODO: bigint?
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exp = d.FieldS("exp", int(n)*8)
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}
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n := d.FieldU("n", int(d.BitsLeft()))
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m := float64(s) * float64(n) * math.Pow(float64(base), float64(exp)) * float64(int(1)<<scale)
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d.FieldValueFlt("value", m)
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case false:
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switch d.FieldBool("decimal_encoding") {
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case true:
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n := d.FieldU6("special", scalar.UintMapSymStr{
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decimalPlusInfinity: "plus_infinity",
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decimalMinusInfinity: "minus_infinity",
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decimalNan: "nan",
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decimalMinusZero: "minus_zero",
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})
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switch n {
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case decimalPlusInfinity:
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d.FieldValueFlt("value", math.Inf(1))
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case decimalMinusInfinity:
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d.FieldValueFlt("value", math.Inf(-1))
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case decimalNan:
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d.FieldValueFlt("value", math.NaN())
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case decimalMinusZero:
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d.FieldValueFlt("value", -0)
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}
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case false:
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d.FieldU6("representation", scalar.UintMapSymStr{
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0b00_00_01: "nr1",
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0b00_00_10: "nr2",
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0b00_00_11: "nr3",
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})
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d.FieldFltFn("value", func(d *decode.D) float64 {
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// TODO: can ParseFloat do all ISO-6093 nr?
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n, _ := strconv.ParseFloat(d.UTF8(int(d.BitsLeft()/8)), 64)
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return n
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})
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}
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}
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}
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case class == classUniversal && tag == universalTypeUTF8string,
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class == classUniversal && tag == universalTypeNumericString,
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class == classUniversal && tag == universalTypePrintableString,
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class == classUniversal && tag == universalTypeTeletexString,
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class == classUniversal && tag == universalTypeVideotexString,
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class == classUniversal && tag == universalTypeIA5String,
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class == classUniversal && tag == universalTypeUTCTime,
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class == classUniversal && tag == universalTypeVisibleString, // not encoded?
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class == classUniversal && tag == universalTypeGeneralString: // not encoded?
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// TODO: restrict?
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s := d.FieldUTF8("value", int(length))
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if sb != nil {
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sb.WriteString(s)
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}
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case class == classUniversal && tag == universalTypeGeneralizedtime:
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d.FieldRawLen("value", int64(length)*8)
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default:
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d.FieldRawLen("value", l)
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}
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})
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}
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func decodeASN1BER(d *decode.D) any {
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decodeASN1BERValue(d, nil, nil, formConstructed, universalTypeSequence)
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return nil
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}
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