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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 13:16:40 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 13:16:40 +0000 |
commit | 47ab3d4a42e9ab51c465c4322d2ec233f6324e6b (patch) | |
tree | a61a0ffd83f4a3def4b36e5c8e99630c559aa723 /src/encoding/asn1/marshal.go | |
parent | Initial commit. (diff) | |
download | golang-1.18-upstream.tar.xz golang-1.18-upstream.zip |
Adding upstream version 1.18.10.upstream/1.18.10upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/encoding/asn1/marshal.go')
-rw-r--r-- | src/encoding/asn1/marshal.go | 747 |
1 files changed, 747 insertions, 0 deletions
diff --git a/src/encoding/asn1/marshal.go b/src/encoding/asn1/marshal.go new file mode 100644 index 0000000..c243349 --- /dev/null +++ b/src/encoding/asn1/marshal.go @@ -0,0 +1,747 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package asn1 + +import ( + "bytes" + "errors" + "fmt" + "math/big" + "reflect" + "sort" + "time" + "unicode/utf8" +) + +var ( + byte00Encoder encoder = byteEncoder(0x00) + byteFFEncoder encoder = byteEncoder(0xff) +) + +// encoder represents an ASN.1 element that is waiting to be marshaled. +type encoder interface { + // Len returns the number of bytes needed to marshal this element. + Len() int + // Encode encodes this element by writing Len() bytes to dst. + Encode(dst []byte) +} + +type byteEncoder byte + +func (c byteEncoder) Len() int { + return 1 +} + +func (c byteEncoder) Encode(dst []byte) { + dst[0] = byte(c) +} + +type bytesEncoder []byte + +func (b bytesEncoder) Len() int { + return len(b) +} + +func (b bytesEncoder) Encode(dst []byte) { + if copy(dst, b) != len(b) { + panic("internal error") + } +} + +type stringEncoder string + +func (s stringEncoder) Len() int { + return len(s) +} + +func (s stringEncoder) Encode(dst []byte) { + if copy(dst, s) != len(s) { + panic("internal error") + } +} + +type multiEncoder []encoder + +func (m multiEncoder) Len() int { + var size int + for _, e := range m { + size += e.Len() + } + return size +} + +func (m multiEncoder) Encode(dst []byte) { + var off int + for _, e := range m { + e.Encode(dst[off:]) + off += e.Len() + } +} + +type setEncoder []encoder + +func (s setEncoder) Len() int { + var size int + for _, e := range s { + size += e.Len() + } + return size +} + +func (s setEncoder) Encode(dst []byte) { + // Per X690 Section 11.6: The encodings of the component values of a + // set-of value shall appear in ascending order, the encodings being + // compared as octet strings with the shorter components being padded + // at their trailing end with 0-octets. + // + // First we encode each element to its TLV encoding and then use + // octetSort to get the ordering expected by X690 DER rules before + // writing the sorted encodings out to dst. + l := make([][]byte, len(s)) + for i, e := range s { + l[i] = make([]byte, e.Len()) + e.Encode(l[i]) + } + + sort.Slice(l, func(i, j int) bool { + // Since we are using bytes.Compare to compare TLV encodings we + // don't need to right pad s[i] and s[j] to the same length as + // suggested in X690. If len(s[i]) < len(s[j]) the length octet of + // s[i], which is the first determining byte, will inherently be + // smaller than the length octet of s[j]. This lets us skip the + // padding step. + return bytes.Compare(l[i], l[j]) < 0 + }) + + var off int + for _, b := range l { + copy(dst[off:], b) + off += len(b) + } +} + +type taggedEncoder struct { + // scratch contains temporary space for encoding the tag and length of + // an element in order to avoid extra allocations. + scratch [8]byte + tag encoder + body encoder +} + +func (t *taggedEncoder) Len() int { + return t.tag.Len() + t.body.Len() +} + +func (t *taggedEncoder) Encode(dst []byte) { + t.tag.Encode(dst) + t.body.Encode(dst[t.tag.Len():]) +} + +type int64Encoder int64 + +func (i int64Encoder) Len() int { + n := 1 + + for i > 127 { + n++ + i >>= 8 + } + + for i < -128 { + n++ + i >>= 8 + } + + return n +} + +func (i int64Encoder) Encode(dst []byte) { + n := i.Len() + + for j := 0; j < n; j++ { + dst[j] = byte(i >> uint((n-1-j)*8)) + } +} + +func base128IntLength(n int64) int { + if n == 0 { + return 1 + } + + l := 0 + for i := n; i > 0; i >>= 7 { + l++ + } + + return l +} + +func appendBase128Int(dst []byte, n int64) []byte { + l := base128IntLength(n) + + for i := l - 1; i >= 0; i-- { + o := byte(n >> uint(i*7)) + o &= 0x7f + if i != 0 { + o |= 0x80 + } + + dst = append(dst, o) + } + + return dst +} + +func makeBigInt(n *big.Int) (encoder, error) { + if n == nil { + return nil, StructuralError{"empty integer"} + } + + if n.Sign() < 0 { + // A negative number has to be converted to two's-complement + // form. So we'll invert and subtract 1. If the + // most-significant-bit isn't set then we'll need to pad the + // beginning with 0xff in order to keep the number negative. + nMinus1 := new(big.Int).Neg(n) + nMinus1.Sub(nMinus1, bigOne) + bytes := nMinus1.Bytes() + for i := range bytes { + bytes[i] ^= 0xff + } + if len(bytes) == 0 || bytes[0]&0x80 == 0 { + return multiEncoder([]encoder{byteFFEncoder, bytesEncoder(bytes)}), nil + } + return bytesEncoder(bytes), nil + } else if n.Sign() == 0 { + // Zero is written as a single 0 zero rather than no bytes. + return byte00Encoder, nil + } else { + bytes := n.Bytes() + if len(bytes) > 0 && bytes[0]&0x80 != 0 { + // We'll have to pad this with 0x00 in order to stop it + // looking like a negative number. + return multiEncoder([]encoder{byte00Encoder, bytesEncoder(bytes)}), nil + } + return bytesEncoder(bytes), nil + } +} + +func appendLength(dst []byte, i int) []byte { + n := lengthLength(i) + + for ; n > 0; n-- { + dst = append(dst, byte(i>>uint((n-1)*8))) + } + + return dst +} + +func lengthLength(i int) (numBytes int) { + numBytes = 1 + for i > 255 { + numBytes++ + i >>= 8 + } + return +} + +func appendTagAndLength(dst []byte, t tagAndLength) []byte { + b := uint8(t.class) << 6 + if t.isCompound { + b |= 0x20 + } + if t.tag >= 31 { + b |= 0x1f + dst = append(dst, b) + dst = appendBase128Int(dst, int64(t.tag)) + } else { + b |= uint8(t.tag) + dst = append(dst, b) + } + + if t.length >= 128 { + l := lengthLength(t.length) + dst = append(dst, 0x80|byte(l)) + dst = appendLength(dst, t.length) + } else { + dst = append(dst, byte(t.length)) + } + + return dst +} + +type bitStringEncoder BitString + +func (b bitStringEncoder) Len() int { + return len(b.Bytes) + 1 +} + +func (b bitStringEncoder) Encode(dst []byte) { + dst[0] = byte((8 - b.BitLength%8) % 8) + if copy(dst[1:], b.Bytes) != len(b.Bytes) { + panic("internal error") + } +} + +type oidEncoder []int + +func (oid oidEncoder) Len() int { + l := base128IntLength(int64(oid[0]*40 + oid[1])) + for i := 2; i < len(oid); i++ { + l += base128IntLength(int64(oid[i])) + } + return l +} + +func (oid oidEncoder) Encode(dst []byte) { + dst = appendBase128Int(dst[:0], int64(oid[0]*40+oid[1])) + for i := 2; i < len(oid); i++ { + dst = appendBase128Int(dst, int64(oid[i])) + } +} + +func makeObjectIdentifier(oid []int) (e encoder, err error) { + if len(oid) < 2 || oid[0] > 2 || (oid[0] < 2 && oid[1] >= 40) { + return nil, StructuralError{"invalid object identifier"} + } + + return oidEncoder(oid), nil +} + +func makePrintableString(s string) (e encoder, err error) { + for i := 0; i < len(s); i++ { + // The asterisk is often used in PrintableString, even though + // it is invalid. If a PrintableString was specifically + // requested then the asterisk is permitted by this code. + // Ampersand is allowed in parsing due a handful of CA + // certificates, however when making new certificates + // it is rejected. + if !isPrintable(s[i], allowAsterisk, rejectAmpersand) { + return nil, StructuralError{"PrintableString contains invalid character"} + } + } + + return stringEncoder(s), nil +} + +func makeIA5String(s string) (e encoder, err error) { + for i := 0; i < len(s); i++ { + if s[i] > 127 { + return nil, StructuralError{"IA5String contains invalid character"} + } + } + + return stringEncoder(s), nil +} + +func makeNumericString(s string) (e encoder, err error) { + for i := 0; i < len(s); i++ { + if !isNumeric(s[i]) { + return nil, StructuralError{"NumericString contains invalid character"} + } + } + + return stringEncoder(s), nil +} + +func makeUTF8String(s string) encoder { + return stringEncoder(s) +} + +func appendTwoDigits(dst []byte, v int) []byte { + return append(dst, byte('0'+(v/10)%10), byte('0'+v%10)) +} + +func appendFourDigits(dst []byte, v int) []byte { + var bytes [4]byte + for i := range bytes { + bytes[3-i] = '0' + byte(v%10) + v /= 10 + } + return append(dst, bytes[:]...) +} + +func outsideUTCRange(t time.Time) bool { + year := t.Year() + return year < 1950 || year >= 2050 +} + +func makeUTCTime(t time.Time) (e encoder, err error) { + dst := make([]byte, 0, 18) + + dst, err = appendUTCTime(dst, t) + if err != nil { + return nil, err + } + + return bytesEncoder(dst), nil +} + +func makeGeneralizedTime(t time.Time) (e encoder, err error) { + dst := make([]byte, 0, 20) + + dst, err = appendGeneralizedTime(dst, t) + if err != nil { + return nil, err + } + + return bytesEncoder(dst), nil +} + +func appendUTCTime(dst []byte, t time.Time) (ret []byte, err error) { + year := t.Year() + + switch { + case 1950 <= year && year < 2000: + dst = appendTwoDigits(dst, year-1900) + case 2000 <= year && year < 2050: + dst = appendTwoDigits(dst, year-2000) + default: + return nil, StructuralError{"cannot represent time as UTCTime"} + } + + return appendTimeCommon(dst, t), nil +} + +func appendGeneralizedTime(dst []byte, t time.Time) (ret []byte, err error) { + year := t.Year() + if year < 0 || year > 9999 { + return nil, StructuralError{"cannot represent time as GeneralizedTime"} + } + + dst = appendFourDigits(dst, year) + + return appendTimeCommon(dst, t), nil +} + +func appendTimeCommon(dst []byte, t time.Time) []byte { + _, month, day := t.Date() + + dst = appendTwoDigits(dst, int(month)) + dst = appendTwoDigits(dst, day) + + hour, min, sec := t.Clock() + + dst = appendTwoDigits(dst, hour) + dst = appendTwoDigits(dst, min) + dst = appendTwoDigits(dst, sec) + + _, offset := t.Zone() + + switch { + case offset/60 == 0: + return append(dst, 'Z') + case offset > 0: + dst = append(dst, '+') + case offset < 0: + dst = append(dst, '-') + } + + offsetMinutes := offset / 60 + if offsetMinutes < 0 { + offsetMinutes = -offsetMinutes + } + + dst = appendTwoDigits(dst, offsetMinutes/60) + dst = appendTwoDigits(dst, offsetMinutes%60) + + return dst +} + +func stripTagAndLength(in []byte) []byte { + _, offset, err := parseTagAndLength(in, 0) + if err != nil { + return in + } + return in[offset:] +} + +func makeBody(value reflect.Value, params fieldParameters) (e encoder, err error) { + switch value.Type() { + case flagType: + return bytesEncoder(nil), nil + case timeType: + t := value.Interface().(time.Time) + if params.timeType == TagGeneralizedTime || outsideUTCRange(t) { + return makeGeneralizedTime(t) + } + return makeUTCTime(t) + case bitStringType: + return bitStringEncoder(value.Interface().(BitString)), nil + case objectIdentifierType: + return makeObjectIdentifier(value.Interface().(ObjectIdentifier)) + case bigIntType: + return makeBigInt(value.Interface().(*big.Int)) + } + + switch v := value; v.Kind() { + case reflect.Bool: + if v.Bool() { + return byteFFEncoder, nil + } + return byte00Encoder, nil + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + return int64Encoder(v.Int()), nil + case reflect.Struct: + t := v.Type() + + for i := 0; i < t.NumField(); i++ { + if !t.Field(i).IsExported() { + return nil, StructuralError{"struct contains unexported fields"} + } + } + + startingField := 0 + + n := t.NumField() + if n == 0 { + return bytesEncoder(nil), nil + } + + // If the first element of the structure is a non-empty + // RawContents, then we don't bother serializing the rest. + if t.Field(0).Type == rawContentsType { + s := v.Field(0) + if s.Len() > 0 { + bytes := s.Bytes() + /* The RawContents will contain the tag and + * length fields but we'll also be writing + * those ourselves, so we strip them out of + * bytes */ + return bytesEncoder(stripTagAndLength(bytes)), nil + } + + startingField = 1 + } + + switch n1 := n - startingField; n1 { + case 0: + return bytesEncoder(nil), nil + case 1: + return makeField(v.Field(startingField), parseFieldParameters(t.Field(startingField).Tag.Get("asn1"))) + default: + m := make([]encoder, n1) + for i := 0; i < n1; i++ { + m[i], err = makeField(v.Field(i+startingField), parseFieldParameters(t.Field(i+startingField).Tag.Get("asn1"))) + if err != nil { + return nil, err + } + } + + return multiEncoder(m), nil + } + case reflect.Slice: + sliceType := v.Type() + if sliceType.Elem().Kind() == reflect.Uint8 { + return bytesEncoder(v.Bytes()), nil + } + + var fp fieldParameters + + switch l := v.Len(); l { + case 0: + return bytesEncoder(nil), nil + case 1: + return makeField(v.Index(0), fp) + default: + m := make([]encoder, l) + + for i := 0; i < l; i++ { + m[i], err = makeField(v.Index(i), fp) + if err != nil { + return nil, err + } + } + + if params.set { + return setEncoder(m), nil + } + return multiEncoder(m), nil + } + case reflect.String: + switch params.stringType { + case TagIA5String: + return makeIA5String(v.String()) + case TagPrintableString: + return makePrintableString(v.String()) + case TagNumericString: + return makeNumericString(v.String()) + default: + return makeUTF8String(v.String()), nil + } + } + + return nil, StructuralError{"unknown Go type"} +} + +func makeField(v reflect.Value, params fieldParameters) (e encoder, err error) { + if !v.IsValid() { + return nil, fmt.Errorf("asn1: cannot marshal nil value") + } + // If the field is an interface{} then recurse into it. + if v.Kind() == reflect.Interface && v.Type().NumMethod() == 0 { + return makeField(v.Elem(), params) + } + + if v.Kind() == reflect.Slice && v.Len() == 0 && params.omitEmpty { + return bytesEncoder(nil), nil + } + + if params.optional && params.defaultValue != nil && canHaveDefaultValue(v.Kind()) { + defaultValue := reflect.New(v.Type()).Elem() + defaultValue.SetInt(*params.defaultValue) + + if reflect.DeepEqual(v.Interface(), defaultValue.Interface()) { + return bytesEncoder(nil), nil + } + } + + // If no default value is given then the zero value for the type is + // assumed to be the default value. This isn't obviously the correct + // behavior, but it's what Go has traditionally done. + if params.optional && params.defaultValue == nil { + if reflect.DeepEqual(v.Interface(), reflect.Zero(v.Type()).Interface()) { + return bytesEncoder(nil), nil + } + } + + if v.Type() == rawValueType { + rv := v.Interface().(RawValue) + if len(rv.FullBytes) != 0 { + return bytesEncoder(rv.FullBytes), nil + } + + t := new(taggedEncoder) + + t.tag = bytesEncoder(appendTagAndLength(t.scratch[:0], tagAndLength{rv.Class, rv.Tag, len(rv.Bytes), rv.IsCompound})) + t.body = bytesEncoder(rv.Bytes) + + return t, nil + } + + matchAny, tag, isCompound, ok := getUniversalType(v.Type()) + if !ok || matchAny { + return nil, StructuralError{fmt.Sprintf("unknown Go type: %v", v.Type())} + } + + if params.timeType != 0 && tag != TagUTCTime { + return nil, StructuralError{"explicit time type given to non-time member"} + } + + if params.stringType != 0 && tag != TagPrintableString { + return nil, StructuralError{"explicit string type given to non-string member"} + } + + switch tag { + case TagPrintableString: + if params.stringType == 0 { + // This is a string without an explicit string type. We'll use + // a PrintableString if the character set in the string is + // sufficiently limited, otherwise we'll use a UTF8String. + for _, r := range v.String() { + if r >= utf8.RuneSelf || !isPrintable(byte(r), rejectAsterisk, rejectAmpersand) { + if !utf8.ValidString(v.String()) { + return nil, errors.New("asn1: string not valid UTF-8") + } + tag = TagUTF8String + break + } + } + } else { + tag = params.stringType + } + case TagUTCTime: + if params.timeType == TagGeneralizedTime || outsideUTCRange(v.Interface().(time.Time)) { + tag = TagGeneralizedTime + } + } + + if params.set { + if tag != TagSequence { + return nil, StructuralError{"non sequence tagged as set"} + } + tag = TagSet + } + + // makeField can be called for a slice that should be treated as a SET + // but doesn't have params.set set, for instance when using a slice + // with the SET type name suffix. In this case getUniversalType returns + // TagSet, but makeBody doesn't know about that so will treat the slice + // as a sequence. To work around this we set params.set. + if tag == TagSet && !params.set { + params.set = true + } + + t := new(taggedEncoder) + + t.body, err = makeBody(v, params) + if err != nil { + return nil, err + } + + bodyLen := t.body.Len() + + class := ClassUniversal + if params.tag != nil { + if params.application { + class = ClassApplication + } else if params.private { + class = ClassPrivate + } else { + class = ClassContextSpecific + } + + if params.explicit { + t.tag = bytesEncoder(appendTagAndLength(t.scratch[:0], tagAndLength{ClassUniversal, tag, bodyLen, isCompound})) + + tt := new(taggedEncoder) + + tt.body = t + + tt.tag = bytesEncoder(appendTagAndLength(tt.scratch[:0], tagAndLength{ + class: class, + tag: *params.tag, + length: bodyLen + t.tag.Len(), + isCompound: true, + })) + + return tt, nil + } + + // implicit tag. + tag = *params.tag + } + + t.tag = bytesEncoder(appendTagAndLength(t.scratch[:0], tagAndLength{class, tag, bodyLen, isCompound})) + + return t, nil +} + +// Marshal returns the ASN.1 encoding of val. +// +// In addition to the struct tags recognised by Unmarshal, the following can be +// used: +// +// ia5: causes strings to be marshaled as ASN.1, IA5String values +// omitempty: causes empty slices to be skipped +// printable: causes strings to be marshaled as ASN.1, PrintableString values +// utf8: causes strings to be marshaled as ASN.1, UTF8String values +// utc: causes time.Time to be marshaled as ASN.1, UTCTime values +// generalized: causes time.Time to be marshaled as ASN.1, GeneralizedTime values +func Marshal(val any) ([]byte, error) { + return MarshalWithParams(val, "") +} + +// MarshalWithParams allows field parameters to be specified for the +// top-level element. The form of the params is the same as the field tags. +func MarshalWithParams(val any, params string) ([]byte, error) { + e, err := makeField(reflect.ValueOf(val), parseFieldParameters(params)) + if err != nil { + return nil, err + } + b := make([]byte, e.Len()) + e.Encode(b) + return b, nil +} |