prometheus/vendor/github.com/dgrijalva/jwt-go/parser.go

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2016-04-06 20:48:01 -07:00
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
}
// 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) {
parts := strings.Split(tokenString, ".")
if len(parts) != 3 {
return nil, &ValidationError{err: "token contains an invalid number of segments", Errors: ValidationErrorMalformed}
}
var err error
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, &ValidationError{err: "tokenstring should not contain 'bearer '", Errors: ValidationErrorMalformed}
}
return token, &ValidationError{err: err.Error(), Errors: ValidationErrorMalformed}
}
if err = json.Unmarshal(headerBytes, &token.Header); err != nil {
return token, &ValidationError{err: err.Error(), Errors: ValidationErrorMalformed}
}
// parse Claims
var claimBytes []byte
if claimBytes, err = DecodeSegment(parts[1]); err != nil {
return token, &ValidationError{err: err.Error(), Errors: ValidationErrorMalformed}
}
dec := json.NewDecoder(bytes.NewBuffer(claimBytes))
if p.UseJSONNumber {
dec.UseNumber()
}
if err = dec.Decode(&token.Claims); err != nil {
return token, &ValidationError{err: err.Error(), Errors: ValidationErrorMalformed}
}
// Lookup signature method
if method, ok := token.Header["alg"].(string); ok {
if token.Method = GetSigningMethod(method); token.Method == nil {
return token, &ValidationError{err: "signing method (alg) is unavailable.", Errors: ValidationErrorUnverifiable}
}
} else {
return token, &ValidationError{err: "signing method (alg) is unspecified.", Errors: ValidationErrorUnverifiable}
}
// 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, &ValidationError{err: fmt.Sprintf("signing method %v is invalid", alg), Errors: ValidationErrorSignatureInvalid}
}
}
// Lookup key
var key interface{}
if keyFunc == nil {
// keyFunc was not provided. short circuiting validation
return token, &ValidationError{err: "no Keyfunc was provided.", Errors: ValidationErrorUnverifiable}
}
if key, err = keyFunc(token); err != nil {
// keyFunc returned an error
return token, &ValidationError{err: err.Error(), Errors: ValidationErrorUnverifiable}
}
// Check expiration times
vErr := &ValidationError{}
now := TimeFunc().Unix()
if exp, ok := token.Claims["exp"].(float64); ok {
if now > int64(exp) {
vErr.err = "token is expired"
vErr.Errors |= ValidationErrorExpired
}
}
if nbf, ok := token.Claims["nbf"].(float64); ok {
if now < int64(nbf) {
vErr.err = "token is not valid yet"
vErr.Errors |= ValidationErrorNotValidYet
}
}
// Perform validation
token.Signature = parts[2]
if err = token.Method.Verify(strings.Join(parts[0:2], "."), token.Signature, key); err != nil {
vErr.err = err.Error()
vErr.Errors |= ValidationErrorSignatureInvalid
}
if vErr.valid() {
token.Valid = true
return token, nil
}
return token, vErr
}