Optimise builder (#47)

algo.go

@@ -8,6 +8,7 @@ import (
 // Signer is used to sign tokens.
 type Signer interface {
 	Algorithm() Algorithm
+	SignSize() int
 	Sign(payload []byte) ([]byte, error)
 }
 
@@ -20,6 +21,8 @@ type Verifier interface {
 // Algorithm for signing and verifying.
 type Algorithm string
 
+func (a Algorithm) String() string { return string(a) }
+
 // Algorithm names for signing and verifying.
 const (
 	EdDSA Algorithm = "EdDSA"

algo_eddsa.go

@@ -36,6 +36,10 @@ func (h edDSAAlg) Algorithm() Algorithm {
 	return h.alg
 }
 
+func (h edDSAAlg) SignSize() int {
+	return ed25519.SignatureSize
+}
+
 func (h edDSAAlg) Sign(payload []byte) ([]byte, error) {
 	return ed25519.Sign(h.privateKey, payload), nil
 }

algo_es.go

@@ -69,6 +69,10 @@ func (h esAlg) Algorithm() Algorithm {
 	return h.alg
 }
 
+func (h esAlg) SignSize() int {
+	return 2 * h.curveBits
+}
+
 func (h esAlg) Sign(payload []byte) ([]byte, error) {
 	signed, err := h.sign(payload)
 	if err != nil {

algo_hs.go

@@ -69,6 +69,10 @@ func (h hsAlg) Algorithm() Algorithm {
 	return h.alg
 }
 
+func (h hsAlg) SignSize() int {
+	return h.hash.Size()
+}
+
 func (h hsAlg) Sign(payload []byte) ([]byte, error) {
 	return h.sign(payload)
 }

algo_ps.go

@@ -78,6 +78,10 @@ type psAlg struct {
 	opts       *rsa.PSSOptions
 }
 
+func (h psAlg) SignSize() int {
+	return h.privateKey.Size()
+}
+
 func (h psAlg) Algorithm() Algorithm {
 	return h.alg
 }

algo_rs.go

@@ -62,6 +62,10 @@ func (h rsAlg) Algorithm() Algorithm {
 	return h.alg
 }
 
+func (h rsAlg) SignSize() int {
+	return h.privateKey.Size()
+}
+
 func (h rsAlg) Sign(payload []byte) ([]byte, error) {
 	signed, err := h.sign(payload)
 	if err != nil {

build.go

@@ -12,8 +12,9 @@ var (
 
 // Builder is used to create a new token.
 type Builder struct {
-	signer Signer
-	header Header
+	signer    Signer
+	header    Header
+	headerRaw []byte
 }
 
 // BuildBytes is used to create and encode JWT with a provided claims.
@@ -30,12 +31,12 @@ func Build(signer Signer, claims interface{}) (*Token, error) {
 func NewBuilder(signer Signer) *Builder {
 	b := &Builder{
 		signer: signer,
-
 		header: Header{
 			Algorithm: signer.Algorithm(),
 			Type:      "JWT",
 		},
 	}
+	b.headerRaw = encodeHeader(&b.header)
 	return b
 }
 
@@ -49,72 +50,116 @@ func (b *Builder) BuildBytes(claims interface{}) ([]byte, error) {
 }
 
 // Build used to create and encode JWT with a provided claims.
+// If claims param is of type []byte then we treat it as a marshaled JSON.
+// In other words you can pass already marshaled claims.
 func (b *Builder) Build(claims interface{}) (*Token, error) {
-	rawClaims, encodedClaims, err := encodeClaims(claims)
+	rawClaims, err := encodeClaims(claims)
 	if err != nil {
 		return nil, err
 	}
 
-	encodedHeader := encodeHeader(&b.header)
-	payload := concatParts(encodedHeader, encodedClaims)
+	lenH := len(b.headerRaw)
+	lenC := base64EncodedLen(len(rawClaims))
+	lenS := base64EncodedLen(b.signer.SignSize())
+
+	raw := make([]byte, lenH+1+lenC+1+lenS)
+	idx := 0
+	idx += copy(raw[idx:], b.headerRaw)
+	raw[idx] = '.'
+	idx++
+	base64Encode(raw[idx:], rawClaims)
+	idx += lenC
 
-	raw, signature, err := signPayload(b.signer, payload)
+	signature, err := b.signer.Sign(raw[:idx])
 	if err != nil {
 		return nil, err
 	}
+	raw[idx] = '.'
+	idx++
+	base64Encode(raw[idx:], signature)
+	idx += lenS
 
 	token := &Token{
 		raw:       raw,
-		payload:   payload,
+		payload:   raw[:lenH+1+lenC],
 		signature: signature,
 		header:    b.header,
 		claims:    rawClaims,
 	}
 	return token, nil
 }
 
-func encodeClaims(claims interface{}) (raw, encoded []byte, err error) {
-	raw, err = json.Marshal(claims)
-	if err != nil {
-		return nil, nil, err
+func encodeClaims(claims interface{}) ([]byte, error) {
+	switch claims := claims.(type) {
+	case []byte:
+		return claims, nil
+	default:
+		return json.Marshal(claims)
 	}
-
-	encoded = make([]byte, base64EncodedLen(len(raw)))
-	base64Encode(encoded, raw)
-
-	return raw, encoded, nil
 }
 
 func encodeHeader(header *Header) []byte {
+	if header.Type == "JWT" && header.ContentType == "" {
+		switch header.Algorithm {
+		case EdDSA:
+			return []byte(encHeaderEdDSA)
+
+		case HS256:
+			return []byte(encHeaderHS256)
+		case HS384:
+			return []byte(encHeaderHS384)
+		case HS512:
+			return []byte(encHeaderHS512)
+
+		case RS256:
+			return []byte(encHeaderRS256)
+		case RS384:
+			return []byte(encHeaderRS384)
+		case RS512:
+			return []byte(encHeaderRS512)
+
+		case ES256:
+			return []byte(encHeaderES256)
+		case ES384:
+			return []byte(encHeaderES384)
+		case ES512:
+			return []byte(encHeaderES512)
+
+		case PS256:
+			return []byte(encHeaderPS256)
+		case PS384:
+			return []byte(encHeaderPS384)
+		case PS512:
+			return []byte(encHeaderPS512)
+
+		default:
+			// another algorithm? encode below
+		}
+	}
 	// returned err is always nil, see *Header.MarshalJSON
-	buf, _ := header.MarshalJSON()
+	buf, _ := json.Marshal(header)
 
 	encoded := make([]byte, base64EncodedLen(len(buf)))
 	base64Encode(encoded, buf)
-
 	return encoded
 }
 
-func signPayload(signer Signer, payload []byte) (signed, signature []byte, err error) {
-	signature, err = signer.Sign(payload)
-	if err != nil {
-		return nil, nil, err
-	}
+const (
+	encHeaderEdDSA = "eyJhbGciOiJFZERTQSIsInR5cCI6IkpXVCJ9"
 
-	encodedSignature := make([]byte, base64EncodedLen(len(signature)))
-	base64Encode(encodedSignature, signature)
+	encHeaderHS256 = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9"
+	encHeaderHS384 = "eyJhbGciOiJIUzM4NCIsInR5cCI6IkpXVCJ9"
+	encHeaderHS512 = "eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9"
 
-	signed = concatParts(payload, encodedSignature)
-
-	return signed, signature, nil
-}
+	encHeaderRS256 = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9"
+	encHeaderRS384 = "eyJhbGciOiJSUzM4NCIsInR5cCI6IkpXVCJ9"
+	encHeaderRS512 = "eyJhbGciOiJSUzUxMiIsInR5cCI6IkpXVCJ9"
 
-func concatParts(a, b []byte) []byte {
-	buf := make([]byte, len(a)+1+len(b))
-	buf[len(a)] = '.'
+	encHeaderES256 = "eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9"
+	encHeaderES384 = "eyJhbGciOiJFUzM4NCIsInR5cCI6IkpXVCJ9"
+	encHeaderES512 = "eyJhbGciOiJFUzUxMiIsInR5cCI6IkpXVCJ9"
 
-	copy(buf[:len(a)], a)
-	copy(buf[len(a)+1:], b)
-
-	return buf
-}
+	encHeaderPS256 = "eyJhbGciOiJQUzI1NiIsInR5cCI6IkpXVCJ9"
+	encHeaderPS384 = "eyJhbGciOiJQUzM4NCIsInR5cCI6IkpXVCJ9"
+	encHeaderPS512 = "eyJhbGciOiJQUzUxMiIsInR5cCI6IkpXVCJ9"
+)

build_test.go

@@ -17,7 +17,7 @@ func TestBuild(t *testing.T) {
 
 		raw := string(token)
 		if raw != want {
-			t.Errorf("want %v, got %v", want, raw)
+			t.Errorf("want %v,\n got %v", want, raw)
 		}
 	}
 
@@ -43,7 +43,7 @@ func TestBuildHeader(t *testing.T) {
 		want = toBase64(want)
 		raw := string(token.RawHeader())
 		if raw != want {
-			t.Errorf("want %v, got %v", want, raw)
+			t.Errorf("\nwant %v,\n got %v", want, raw)
 		}
 	}
 
@@ -109,6 +109,9 @@ func toBase64(s string) string {
 
 type badSigner struct{}
 
+func (badSigner) SignSize() int {
+	return 0
+}
 func (badSigner) Algorithm() Algorithm {
 	return "bad"
 }

jwt.go

@@ -67,7 +67,7 @@ type Header struct {
 }
 
 // MarshalJSON implements the json.Marshaler interface.
-func (h *Header) MarshalJSON() (data []byte, err error) {
+func (h *Header) MarshalJSON() ([]byte, error) {
 	buf := bytes.Buffer{}
 	buf.WriteString(`{"alg":"`)
 	buf.WriteString(string(h.Algorithm))

jwt_bench_test.go

@@ -13,7 +13,7 @@ import (
 	"github.com/cristalhq/jwt/v2"
 )
 
-func BenchmarkEDSA(b *testing.B) {
+func BenchmarkAlgEDSA(b *testing.B) {
 	pubKey, privKey, keyErr := ed25519.GenerateKey(rand.Reader)
 	if keyErr != nil {
 		b.Fatal(keyErr)
@@ -35,7 +35,7 @@ func BenchmarkEDSA(b *testing.B) {
 	})
 }
 
-func BenchmarkES(b *testing.B) {
+func BenchmarkAlgES(b *testing.B) {
 	esAlgos := map[jwt.Algorithm]elliptic.Curve{
 		jwt.ES256: elliptic.P256(),
 		jwt.ES384: elliptic.P384(),
@@ -64,7 +64,7 @@ func BenchmarkES(b *testing.B) {
 	}
 }
 
-func BenchmarkPS(b *testing.B) {
+func BenchmarkAlgPS(b *testing.B) {
 	psAlgos := []jwt.Algorithm{jwt.PS256, jwt.PS384, jwt.PS512}
 	for _, algo := range psAlgos {
 		key, keyErr := rsa.GenerateKey(rand.Reader, 2048)
@@ -89,7 +89,7 @@ func BenchmarkPS(b *testing.B) {
 	}
 }
 
-func BenchmarkRS(b *testing.B) {
+func BenchmarkAlgRS(b *testing.B) {
 	rsAlgos := []jwt.Algorithm{jwt.RS256, jwt.RS384, jwt.RS512}
 	for _, algo := range rsAlgos {
 		key, keyErr := rsa.GenerateKey(rand.Reader, 2048)
@@ -114,7 +114,7 @@ func BenchmarkRS(b *testing.B) {
 	}
 }
 
-func BenchmarkHS(b *testing.B) {
+func BenchmarkAlgHS(b *testing.B) {
 	key := []byte("12345")
 	hsAlgos := []jwt.Algorithm{jwt.HS256, jwt.HS384, jwt.HS512}
 	for _, algo := range hsAlgos {