implement SASL OAUTHBEARER and draft/bearer (#2122)

* implement SASL OAUTHBEARER and draft/bearer
* Upgrade JWT lib
* Fix an edge case in SASL EXTERNAL
* Accept longer SASL responses
* review fix: allow multiple token definitions
* enhance tests
* use SASL utilities from irc-go
* test expired tokens

vendor/github.com/golang-jwt/jwt/v5/ed25519.go

@@ -0,0 +1,79 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/ed25519"
+	"crypto/rand"
+	"errors"
+)
+
+var (
+	ErrEd25519Verification = errors.New("ed25519: verification error")
+)
+
+// SigningMethodEd25519 implements the EdDSA family.
+// Expects ed25519.PrivateKey for signing and ed25519.PublicKey for verification
+type SigningMethodEd25519 struct{}
+
+// Specific instance for EdDSA
+var (
+	SigningMethodEdDSA *SigningMethodEd25519
+)
+
+func init() {
+	SigningMethodEdDSA = &SigningMethodEd25519{}
+	RegisterSigningMethod(SigningMethodEdDSA.Alg(), func() SigningMethod {
+		return SigningMethodEdDSA
+	})
+}
+
+func (m *SigningMethodEd25519) Alg() string {
+	return "EdDSA"
+}
+
+// Verify implements token verification for the SigningMethod.
+// For this verify method, key must be an ed25519.PublicKey
+func (m *SigningMethodEd25519) Verify(signingString string, sig []byte, key interface{}) error {
+	var ed25519Key ed25519.PublicKey
+	var ok bool
+
+	if ed25519Key, ok = key.(ed25519.PublicKey); !ok {
+		return newError("Ed25519 verify expects ed25519.PublicKey", ErrInvalidKeyType)
+	}
+
+	if len(ed25519Key) != ed25519.PublicKeySize {
+		return ErrInvalidKey
+	}
+
+	// Verify the signature
+	if !ed25519.Verify(ed25519Key, []byte(signingString), sig) {
+		return ErrEd25519Verification
+	}
+
+	return nil
+}
+
+// Sign implements token signing for the SigningMethod.
+// For this signing method, key must be an ed25519.PrivateKey
+func (m *SigningMethodEd25519) Sign(signingString string, key interface{}) ([]byte, error) {
+	var ed25519Key crypto.Signer
+	var ok bool
+
+	if ed25519Key, ok = key.(crypto.Signer); !ok {
+		return nil, newError("Ed25519 sign expects crypto.Signer", ErrInvalidKeyType)
+	}
+
+	if _, ok := ed25519Key.Public().(ed25519.PublicKey); !ok {
+		return nil, ErrInvalidKey
+	}
+
+	// Sign the string and return the result. ed25519 performs a two-pass hash
+	// as part of its algorithm. Therefore, we need to pass a non-prehashed
+	// message into the Sign function, as indicated by crypto.Hash(0)
+	sig, err := ed25519Key.Sign(rand.Reader, []byte(signingString), crypto.Hash(0))
+	if err != nil {
+		return nil, err
+	}
+
+	return sig, nil
+}