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asn1_util.go
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/
asn1_util.go
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/*
Copyright 2023 The cert-manager Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// This file contains some code copied from the Go standard library under the following license: https://github.com/golang/go/blob/c95fe91d0715dc0a8d55ac80a80f383c3635548b/LICENSE
package pki
import (
"encoding/asn1"
"errors"
"fmt"
"strconv"
"strings"
"unicode"
"unicode/utf8"
)
// ParseObjectIdentifier parses an object identifier from its string representation.
func ParseObjectIdentifier(oidString string) (oid asn1.ObjectIdentifier, err error) {
if len(oidString) == 0 {
return nil, errors.New("zero length OBJECT IDENTIFIER")
}
parts := strings.Split(oidString, ".")
oid = make(asn1.ObjectIdentifier, 0, len(parts))
for _, part := range parts {
value, err := strconv.Atoi(part)
if err != nil {
return nil, err
}
oid = append(oid, value)
}
return oid, nil
}
type UniversalValueType int
const (
UniversalValueTypeBytes UniversalValueType = iota
UniversalValueTypeIA5String
UniversalValueTypeUTF8String
UniversalValueTypePrintableString
)
type UniversalValue struct {
Bytes []byte
IA5String string
UTF8String string
PrintableString string
}
func (uv UniversalValue) Type() UniversalValueType {
isBytes := uv.Bytes != nil
isIA5String := uv.IA5String != ""
isUTF8String := uv.UTF8String != ""
isPrintableString := uv.PrintableString != ""
switch {
case isBytes && !isIA5String && !isUTF8String && !isPrintableString:
return UniversalValueTypeBytes
case !isBytes && isIA5String && !isUTF8String && !isPrintableString:
return UniversalValueTypeIA5String
case !isBytes && !isIA5String && isUTF8String && !isPrintableString:
return UniversalValueTypeUTF8String
case !isBytes && !isIA5String && !isUTF8String && isPrintableString:
return UniversalValueTypePrintableString
}
return -1 // Either no field is set or two fields are set.
}
func MarshalUniversalValue(uv UniversalValue) ([]byte, error) {
// Make sure we have only one field set
uvType := uv.Type()
var bytes []byte
switch uvType {
case -1:
return nil, errors.New("UniversalValue should have exactly one field set")
case UniversalValueTypeBytes:
bytes = uv.Bytes
default:
rawValue := asn1.RawValue{
Class: asn1.ClassUniversal,
IsCompound: false,
}
switch uvType {
case UniversalValueTypeIA5String:
if err := isIA5String(uv.IA5String); err != nil {
return nil, errors.New("asn1: invalid IA5 string")
}
rawValue.Tag = asn1.TagIA5String
rawValue.Bytes = []byte(uv.IA5String)
case UniversalValueTypeUTF8String:
if !utf8.ValidString(uv.UTF8String) {
return nil, errors.New("asn1: invalid UTF-8 string")
}
rawValue.Tag = asn1.TagUTF8String
rawValue.Bytes = []byte(uv.UTF8String)
case UniversalValueTypePrintableString:
if !isPrintable(uv.PrintableString) {
return nil, errors.New("asn1: invalid PrintableString string")
}
rawValue.Tag = asn1.TagPrintableString
rawValue.Bytes = []byte(uv.PrintableString)
}
universalBytes, err := asn1.Marshal(rawValue)
if err != nil {
return nil, err
}
bytes = universalBytes
}
return bytes, nil
}
func UnmarshalUniversalValue(rawValue asn1.RawValue) (UniversalValue, error) {
var uv UniversalValue
if rawValue.FullBytes == nil {
fullBytes, err := asn1.Marshal(rawValue)
if err != nil {
return uv, err
}
rawValue.FullBytes = fullBytes
}
var rest []byte
var err error
if rawValue.Tag == asn1.TagIA5String {
rest, err = asn1.UnmarshalWithParams(rawValue.FullBytes, &uv.IA5String, "ia5")
} else if rawValue.Tag == asn1.TagUTF8String {
rest, err = asn1.UnmarshalWithParams(rawValue.FullBytes, &uv.UTF8String, "utf8")
} else if rawValue.Tag == asn1.TagPrintableString {
rest, err = asn1.UnmarshalWithParams(rawValue.FullBytes, &uv.PrintableString, "printable")
} else {
uv.Bytes = rawValue.FullBytes
}
if err != nil {
return uv, err
}
if len(rest) != 0 {
return uv, fmt.Errorf("trailing data")
}
return uv, nil
}
// Copied from: https://github.com/golang/go/blob/c95fe91d0715dc0a8d55ac80a80f383c3635548b/src/crypto/x509/x509.go#L1093
func isIA5String(s string) error {
for _, r := range s {
// Per RFC5280 "IA5String is limited to the set of ASCII characters"
if r > unicode.MaxASCII {
return fmt.Errorf("x509: %q cannot be encoded as an IA5String", s)
}
}
return nil
}
// isPrintable reports whether the given b is in the ASN.1 PrintableString set.
// '*' and '&' are also allowed, reflecting existing practice.
// Copied from: https://github.com/golang/go/blob/c95fe91d0715dc0a8d55ac80a80f383c3635548b/src/crypto/x509/parser.go#L34
func isPrintable(s string) bool {
for _, b := range s {
if '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 == '*' ||
// This is not technically allowed either. However, not
// only is it relatively common, but there are also a
// handful of CA certificates that contain it. At least
// one of which will not expire until 2027.
b == '&' {
continue
}
return false
}
return true
}