crypto/x509: add new OID type and use it in Certificate

api/next/60665.txt

@@ -0,0 +1,6 @@
+pkg crypto/x509, type Certificate struct, Policies []OID #60665
+pkg crypto/x509, type OID struct #60665
+pkg crypto/x509, method (OID) Equal(OID) bool #60665
+pkg crypto/x509, method (OID) EqualASN1OID(asn1.ObjectIdentifier) bool #60665
+pkg crypto/x509, method (OID) String() string #60665
+pkg crypto/x509, func OIDFromInts([]uint64) (OID, error) #60665

src/crypto/x509/oid.go

@@ -0,0 +1,273 @@
+// Copyright 2023 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 x509
+
+import (
+	"bytes"
+	"encoding/asn1"
+	"errors"
+	"math"
+	"math/big"
+	"math/bits"
+	"strconv"
+	"strings"
+)
+
+var (
+	errInvalidOID = errors.New("invalid oid")
+)
+
+// An OID represents an ASN.1 OBJECT IDENTIFIER.
+type OID struct {
+	der []byte
+}
+
+func newOIDFromDER(der []byte) (OID, bool) {
+	if len(der) == 0 || der[len(der)-1]&0x80 != 0 {
+		return OID{}, false
+	}
+
+	start := 0
+	for i, v := range der {
+		// ITU-T X.690, section 8.19.2:
+		// The subidentifier shall be encoded in the fewest possible octets,
+		// that is, the leading octet of the subidentifier shall not have the value 0x80.
+		if i == start && v == 0x80 {
+			return OID{}, false
+		}
+		if v&0x80 == 0 {
+			start = i + 1
+		}
+	}
+
+	return OID{der}, true
+}
+
+// OIDFromInts creates a new OID using ints, each integer is a separate component.
+func OIDFromInts(oid []uint64) (OID, error) {
+	if len(oid) < 2 || oid[0] > 2 || (oid[0] < 2 && oid[1] >= 40) {
+		return OID{}, errInvalidOID
+	}
+
+	length := base128IntLength(oid[0]*40 + oid[1])
+	for _, v := range oid[2:] {
+		length += base128IntLength(v)
+	}
+
+	der := make([]byte, 0, length)
+	der = appendBase128Int(der, oid[0]*40+oid[1])
+	for _, v := range oid[2:] {
+		der = appendBase128Int(der, v)
+	}
+	return OID{der}, nil
+}
+
+func base128IntLength(n uint64) int {
+	if n == 0 {
+		return 1
+	}
+	return (bits.Len64(n) + 6) / 7
+}
+
+func appendBase128Int(dst []byte, n uint64) []byte {
+	for i := base128IntLength(n) - 1; i >= 0; i-- {
+		o := byte(n >> uint(i*7))
+		o &= 0x7f
+		if i != 0 {
+			o |= 0x80
+		}
+		dst = append(dst, o)
+	}
+	return dst
+}
+
+// Equal returns true when oid and other represents the same Object Identifier.
+func (oid OID) Equal(other OID) bool {
+	// There is only one possible DER encoding of
+	// each unique Object Identifier.
+	return bytes.Equal(oid.der, other.der)
+}
+
+func parseBase128Int(bytes []byte, initOffset int) (ret, offset int, failed bool) {
+	offset = initOffset
+	var ret64 int64
+	for shifted := 0; offset < len(bytes); shifted++ {
+		// 5 * 7 bits per byte == 35 bits of data
+		// Thus the representation is either non-minimal or too large for an int32
+		if shifted == 5 {
+			failed = true
+			return
+		}
+		ret64 <<= 7
+		b := bytes[offset]
+		// integers should be minimally encoded, so the leading octet should
+		// never be 0x80
+		if shifted == 0 && b == 0x80 {
+			failed = true
+			return
+		}
+		ret64 |= int64(b & 0x7f)
+		offset++
+		if b&0x80 == 0 {
+			ret = int(ret64)
+			// Ensure that the returned value fits in an int on all platforms
+			if ret64 > math.MaxInt32 {
+				failed = true
+			}
+			return
+		}
+	}
+	failed = true
+	return
+}
+
+// EqualASN1OID returns whether an OID equals an asn1.ObjectIdentifier. If
+// asn1.ObjectIdentifier cannot represent the OID specified by oid, because
+// a component of OID requires more than 31 bits, it returns false.
+func (oid OID) EqualASN1OID(other asn1.ObjectIdentifier) bool {
+	if len(other) < 2 {
+		return false
+	}
+	v, offset, failed := parseBase128Int(oid.der, 0)
+	if failed {
+		// This should never happen, since we've already parsed the OID,
+		// but just in case.
+		return false
+	}
+	if v < 80 {
+		a, b := v/40, v%40
+		if other[0] != a || other[1] != b {
+			return false
+		}
+	} else {
+		a, b := 2, v-80
+		if other[0] != a || other[1] != b {
+			return false
+		}
+	}
+
+	i := 2
+	for ; offset < len(oid.der); i++ {
+		v, offset, failed = parseBase128Int(oid.der, offset)
+		if failed {
+			// Again, shouldn't happen, since we've already parsed
+			// the OID, but better safe than sorry.
+			return false
+		}
+		if v != other[i] {
+			return false
+		}
+	}
+
+	return i == len(other)
+}
+
+// Strings returns the string representation of the Object Identifier.
+func (oid OID) String() string {
+	var b strings.Builder
+	b.Grow(32)
+	const (
+		valSize         = 64 // size in bits of val.
+		bitsPerByte     = 7
+		maxValSafeShift = (1 << (valSize - bitsPerByte)) - 1
+	)
+	var (
+		start    = 0
+		val      = uint64(0)
+		numBuf   = make([]byte, 0, 21)
+		bigVal   *big.Int
+		overflow bool
+	)
+	for i, v := range oid.der {
+		curVal := v & 0x7F
+		valEnd := v&0x80 == 0
+		if valEnd {
+			if start != 0 {
+				b.WriteByte('.')
+			}
+		}
+		if !overflow && val > maxValSafeShift {
+			if bigVal == nil {
+				bigVal = new(big.Int)
+			}
+			bigVal = bigVal.SetUint64(val)
+			overflow = true
+		}
+		if overflow {
+			bigVal = bigVal.Lsh(bigVal, bitsPerByte).Or(bigVal, big.NewInt(int64(curVal)))
+			if valEnd {
+				if start == 0 {
+					b.WriteString("2.")
+					bigVal = bigVal.Sub(bigVal, big.NewInt(80))
+				}
+				numBuf = bigVal.Append(numBuf, 10)
+				b.Write(numBuf)
+				numBuf = numBuf[:0]
+				val = 0
+				start = i + 1
+				overflow = false
+			}
+			continue
+		}
+		val <<= bitsPerByte
+		val |= uint64(curVal)
+		if valEnd {
+			if start == 0 {
+				if val < 80 {
+					b.Write(strconv.AppendUint(numBuf, val/40, 10))
+					b.WriteByte('.')
+					b.Write(strconv.AppendUint(numBuf, val%40, 10))
+				} else {
+					b.WriteString("2.")
+					b.Write(strconv.AppendUint(numBuf, val-80, 10))
+				}
+			} else {
+				b.Write(strconv.AppendUint(numBuf, val, 10))
+			}
+			val = 0
+			start = i + 1
+		}
+	}
+	return b.String()
+}
+
+func (oid OID) toASN1OID() (asn1.ObjectIdentifier, bool) {
+	out := make([]int, 0, len(oid.der)+1)
+
+	const (
+		valSize         = 31 // amount of usable bits of val for OIDs.
+		bitsPerByte     = 7
+		maxValSafeShift = (1 << (valSize - bitsPerByte)) - 1
+	)
+
+	val := 0
+
+	for _, v := range oid.der {
+		if val > maxValSafeShift {
+			return nil, false
+		}
+
+		val <<= bitsPerByte
+		val |= int(v & 0x7F)
+
+		if v&0x80 == 0 {
+			if len(out) == 0 {
+				if val < 80 {
+					out = append(out, val/40)
+					out = append(out, val%40)
+				} else {
+					out = append(out, 2)
+					out = append(out, val-80)
+				}
+				val = 0
+				continue
+			}
+			out = append(out, val)
+			val = 0
+		}
+	}
+
+	return out, true
+}

src/crypto/x509/oid_test.go

@@ -0,0 +1,110 @@
+// Copyright 2023 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 x509
+
+import (
+	"encoding/asn1"
+	"math"
+	"testing"
+)
+
+func TestOID(t *testing.T) {
+	var tests = []struct {
+		raw   []byte
+		valid bool
+		str   string
+		ints  []uint64
+	}{
+		{[]byte{}, false, "", nil},
+		{[]byte{0x80, 0x01}, false, "", nil},
+		{[]byte{0x01, 0x80, 0x01}, false, "", nil},
+
+		{[]byte{1, 2, 3}, true, "0.1.2.3", []uint64{0, 1, 2, 3}},
+		{[]byte{41, 2, 3}, true, "1.1.2.3", []uint64{1, 1, 2, 3}},
+		{[]byte{86, 2, 3}, true, "2.6.2.3", []uint64{2, 6, 2, 3}},
+
+		{[]byte{41, 255, 255, 255, 127}, true, "1.1.268435455", []uint64{1, 1, 268435455}},
+		{[]byte{41, 0x87, 255, 255, 255, 127}, true, "1.1.2147483647", []uint64{1, 1, 2147483647}},
+		{[]byte{41, 255, 255, 255, 255, 127}, true, "1.1.34359738367", []uint64{1, 1, 34359738367}},
+		{[]byte{42, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "1.2.9223372036854775807", []uint64{1, 2, 9223372036854775807}},
+		{[]byte{43, 0x81, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "1.3.18446744073709551615", []uint64{1, 3, 18446744073709551615}},
+		{[]byte{44, 0x83, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "1.4.36893488147419103231", nil},
+		{[]byte{85, 255, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "2.5.1180591620717411303423", nil},
+		{[]byte{85, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "2.5.19342813113834066795298815", nil},
+
+		{[]byte{255, 255, 255, 127}, true, "2.268435375", []uint64{2, 268435375}},
+		{[]byte{0x87, 255, 255, 255, 127}, true, "2.2147483567", []uint64{2, 2147483567}},
+		{[]byte{255, 127}, true, "2.16303", []uint64{2, 16303}},
+		{[]byte{255, 255, 255, 255, 127}, true, "2.34359738287", []uint64{2, 34359738287}},
+		{[]byte{255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "2.9223372036854775727", []uint64{2, 9223372036854775727}},
+		{[]byte{0x81, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "2.18446744073709551535", []uint64{2, 18446744073709551535}},
+		{[]byte{0x83, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "2.36893488147419103151", nil},
+		{[]byte{255, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "2.1180591620717411303343", nil},
+		{[]byte{255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 127}, true, "2.19342813113834066795298735", nil},
+	}
+
+	for _, v := range tests {
+		oid, ok := newOIDFromDER(v.raw)
+		if ok != v.valid {
+			if ok {
+				t.Errorf("%v: unexpected success while parsing: %v", v.raw, oid)
+			} else {
+				t.Errorf("%v: unexpected failure while parsing", v.raw)
+			}
+			continue
+		}
+
+		if !ok {
+			continue
+		}
+
+		if str := oid.String(); str != v.str {
+			t.Errorf("%v: oid.String() = %v, want; %v", v.raw, str, v.str)
+		}
+
+		var asn1OID asn1.ObjectIdentifier
+		for _, v := range v.ints {
+			if v > math.MaxInt32 {
+				asn1OID = nil
+				break
+			}
+			asn1OID = append(asn1OID, int(v))
+		}
+
+		o, ok := oid.toASN1OID()
+		if shouldOk := asn1OID != nil; shouldOk != ok {
+			if ok {
+				t.Errorf("%v: oid.toASN1OID() unexpected success", v.raw)
+			} else {
+				t.Errorf("%v: oid.toASN1OID() unexpected fauilure", v.raw)
+			}
+			continue
+		}
+
+		if asn1OID != nil {
+			if !o.Equal(asn1OID) {
+				t.Errorf("%v: oid.toASN1OID(asn1OID).Equal(oid) = false, want: true", v.raw)
+			}
+		}
+
+		if v.ints != nil {
+			oid2, err := OIDFromInts(v.ints)
+			if err != nil {
+				t.Errorf("%v: OIDFromInts() unexpected error: %v", v.raw, err)
+			}
+			if !oid2.Equal(oid) {
+				t.Errorf("%v: %#v.Equal(%#v) = false, want: true", v.raw, oid2, oid)
+			}
+		}
+	}
+}
+
+func mustNewOIDFromInts(t *testing.T, ints []uint64) OID {
+	oid, err := OIDFromInts(ints)
+	if err != nil {
+		t.Fatalf("OIDFromInts(%v) unexpected error: %v", ints, err)
+	}
+	return oid
+}