switch to maintained lib (#16532)

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Andrew Thornton <art27@cantab.net>

vendor/github.com/golang-jwt/jwt/parser.go

@@ -0,0 +1,148 @@
+package jwt
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+type Parser struct {
+	ValidMethods         []string // If populated, only these methods will be considered valid
+	UseJSONNumber        bool     // Use JSON Number format in JSON decoder
+	SkipClaimsValidation bool     // Skip claims validation during token parsing
+}
+
+// Parse, validate, and return a token.
+// keyFunc will receive the parsed token and should return the key for validating.
+// If everything is kosher, err will be nil
+func (p *Parser) Parse(tokenString string, keyFunc Keyfunc) (*Token, error) {
+	return p.ParseWithClaims(tokenString, MapClaims{}, keyFunc)
+}
+
+func (p *Parser) ParseWithClaims(tokenString string, claims Claims, keyFunc Keyfunc) (*Token, error) {
+	token, parts, err := p.ParseUnverified(tokenString, claims)
+	if err != nil {
+		return token, err
+	}
+
+	// Verify signing method is in the required set
+	if p.ValidMethods != nil {
+		var signingMethodValid = false
+		var alg = token.Method.Alg()
+		for _, m := range p.ValidMethods {
+			if m == alg {
+				signingMethodValid = true
+				break
+			}
+		}
+		if !signingMethodValid {
+			// signing method is not in the listed set
+			return token, NewValidationError(fmt.Sprintf("signing method %v is invalid", alg), ValidationErrorSignatureInvalid)
+		}
+	}
+
+	// Lookup key
+	var key interface{}
+	if keyFunc == nil {
+		// keyFunc was not provided.  short circuiting validation
+		return token, NewValidationError("no Keyfunc was provided.", ValidationErrorUnverifiable)
+	}
+	if key, err = keyFunc(token); err != nil {
+		// keyFunc returned an error
+		if ve, ok := err.(*ValidationError); ok {
+			return token, ve
+		}
+		return token, &ValidationError{Inner: err, Errors: ValidationErrorUnverifiable}
+	}
+
+	vErr := &ValidationError{}
+
+	// Validate Claims
+	if !p.SkipClaimsValidation {
+		if err := token.Claims.Valid(); err != nil {
+
+			// If the Claims Valid returned an error, check if it is a validation error,
+			// If it was another error type, create a ValidationError with a generic ClaimsInvalid flag set
+			if e, ok := err.(*ValidationError); !ok {
+				vErr = &ValidationError{Inner: err, Errors: ValidationErrorClaimsInvalid}
+			} else {
+				vErr = e
+			}
+		}
+	}
+
+	// Perform validation
+	token.Signature = parts[2]
+	if err = token.Method.Verify(strings.Join(parts[0:2], "."), token.Signature, key); err != nil {
+		vErr.Inner = err
+		vErr.Errors |= ValidationErrorSignatureInvalid
+	}
+
+	if vErr.valid() {
+		token.Valid = true
+		return token, nil
+	}
+
+	return token, vErr
+}
+
+// WARNING: Don't use this method unless you know what you're doing
+//
+// This method parses the token but doesn't validate the signature. It's only
+// ever useful in cases where you know the signature is valid (because it has
+// been checked previously in the stack) and you want to extract values from
+// it.
+func (p *Parser) ParseUnverified(tokenString string, claims Claims) (token *Token, parts []string, err error) {
+	parts = strings.Split(tokenString, ".")
+	if len(parts) != 3 {
+		return nil, parts, NewValidationError("token contains an invalid number of segments", ValidationErrorMalformed)
+	}
+
+	token = &Token{Raw: tokenString}
+
+	// parse Header
+	var headerBytes []byte
+	if headerBytes, err = DecodeSegment(parts[0]); err != nil {
+		if strings.HasPrefix(strings.ToLower(tokenString), "bearer ") {
+			return token, parts, NewValidationError("tokenstring should not contain 'bearer '", ValidationErrorMalformed)
+		}
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+	if err = json.Unmarshal(headerBytes, &token.Header); err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+
+	// parse Claims
+	var claimBytes []byte
+	token.Claims = claims
+
+	if claimBytes, err = DecodeSegment(parts[1]); err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+	dec := json.NewDecoder(bytes.NewBuffer(claimBytes))
+	if p.UseJSONNumber {
+		dec.UseNumber()
+	}
+	// JSON Decode.  Special case for map type to avoid weird pointer behavior
+	if c, ok := token.Claims.(MapClaims); ok {
+		err = dec.Decode(&c)
+	} else {
+		err = dec.Decode(&claims)
+	}
+	// Handle decode error
+	if err != nil {
+		return token, parts, &ValidationError{Inner: err, Errors: ValidationErrorMalformed}
+	}
+
+	// Lookup signature method
+	if method, ok := token.Header["alg"].(string); ok {
+		if token.Method = GetSigningMethod(method); token.Method == nil {
+			return token, parts, NewValidationError("signing method (alg) is unavailable.", ValidationErrorUnverifiable)
+		}
+	} else {
+		return token, parts, NewValidationError("signing method (alg) is unspecified.", ValidationErrorUnverifiable)
+	}
+
+	return token, parts, nil
+}