117 lines
3.6 KiB
Go
117 lines
3.6 KiB
Go
package jwt
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"strings"
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)
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type Parser struct {
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ValidMethods []string // If populated, only these methods will be considered valid
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UseJSONNumber bool // Use JSON Number format in JSON decoder
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}
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// Parse, validate, and return a token.
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// keyFunc will receive the parsed token and should return the key for validating.
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// If everything is kosher, err will be nil
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func (p *Parser) Parse(tokenString string, keyFunc Keyfunc) (*Token, error) {
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parts := strings.Split(tokenString, ".")
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if len(parts) != 3 {
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return nil, &ValidationError{err: "token contains an invalid number of segments", Errors: ValidationErrorMalformed}
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}
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var err error
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token := &Token{Raw: tokenString}
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// parse Header
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var headerBytes []byte
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if headerBytes, err = DecodeSegment(parts[0]); err != nil {
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if strings.HasPrefix(strings.ToLower(tokenString), "bearer ") {
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return token, &ValidationError{err: "tokenstring should not contain 'bearer '", Errors: ValidationErrorMalformed}
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}
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return token, &ValidationError{err: err.Error(), Errors: ValidationErrorMalformed}
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}
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if err = json.Unmarshal(headerBytes, &token.Header); err != nil {
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return token, &ValidationError{err: err.Error(), Errors: ValidationErrorMalformed}
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}
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// parse Claims
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var claimBytes []byte
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if claimBytes, err = DecodeSegment(parts[1]); err != nil {
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return token, &ValidationError{err: err.Error(), Errors: ValidationErrorMalformed}
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}
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dec := json.NewDecoder(bytes.NewBuffer(claimBytes))
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if p.UseJSONNumber {
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dec.UseNumber()
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}
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if err = dec.Decode(&token.Claims); err != nil {
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return token, &ValidationError{err: err.Error(), Errors: ValidationErrorMalformed}
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}
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// Lookup signature method
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if method, ok := token.Header["alg"].(string); ok {
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if token.Method = GetSigningMethod(method); token.Method == nil {
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return token, &ValidationError{err: "signing method (alg) is unavailable.", Errors: ValidationErrorUnverifiable}
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}
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} else {
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return token, &ValidationError{err: "signing method (alg) is unspecified.", Errors: ValidationErrorUnverifiable}
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}
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// Verify signing method is in the required set
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if p.ValidMethods != nil {
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var signingMethodValid = false
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var alg = token.Method.Alg()
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for _, m := range p.ValidMethods {
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if m == alg {
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signingMethodValid = true
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break
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}
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}
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if !signingMethodValid {
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// signing method is not in the listed set
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return token, &ValidationError{err: fmt.Sprintf("signing method %v is invalid", alg), Errors: ValidationErrorSignatureInvalid}
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}
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}
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// Lookup key
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var key interface{}
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if keyFunc == nil {
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// keyFunc was not provided. short circuiting validation
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return token, &ValidationError{err: "no Keyfunc was provided.", Errors: ValidationErrorUnverifiable}
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}
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if key, err = keyFunc(token); err != nil {
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// keyFunc returned an error
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return token, &ValidationError{err: err.Error(), Errors: ValidationErrorUnverifiable}
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}
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// Check expiration times
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vErr := &ValidationError{}
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now := TimeFunc().Unix()
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if exp, ok := token.Claims["exp"].(float64); ok {
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if now > int64(exp) {
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vErr.err = "token is expired"
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vErr.Errors |= ValidationErrorExpired
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}
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}
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if nbf, ok := token.Claims["nbf"].(float64); ok {
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if now < int64(nbf) {
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vErr.err = "token is not valid yet"
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vErr.Errors |= ValidationErrorNotValidYet
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}
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}
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// Perform validation
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token.Signature = parts[2]
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if err = token.Method.Verify(strings.Join(parts[0:2], "."), token.Signature, key); err != nil {
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vErr.err = err.Error()
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vErr.Errors |= ValidationErrorSignatureInvalid
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}
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if vErr.valid() {
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token.Valid = true
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return token, nil
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}
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return token, vErr
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}
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