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nerd_token.go
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/
nerd_token.go
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package credentials
import (
"crypto/ecdsa"
"crypto/x509"
"encoding/pem"
jwt "github.com/dgrijalva/jwt-go"
"github.com/nerdalize/nerd/nerd/payload"
"github.com/pkg/errors"
)
const (
NerdTokenEnvVar = "NERD_TOKEN"
)
//DecodeTokenWithKey decodes a nerd token (JWT) and verifies it with the given public key.
func DecodeTokenWithKey(nerdToken string, key *ecdsa.PublicKey) (*payload.NerdClaims, error) {
return decodeToken(nerdToken, key)
}
//DecodeTokenWithPEM decodes a nerd token (JWT) and verifies it with the given public key in PEM format.
func DecodeTokenWithPEM(nerdToken, pem string) (*payload.NerdClaims, error) {
key, err := ParseECDSAPublicKeyFromPemBytes([]byte(pem))
if err != nil {
return nil, errors.Wrap(err, "failed to parse public key PEM to ecdsa key")
}
return decodeToken(nerdToken, key)
}
//decodeToken decodes a nerd token (JWT) given the public key to check if the signature is valid.
func decodeToken(nerdToken string, key *ecdsa.PublicKey) (*payload.NerdClaims, error) {
p := &jwt.Parser{
SkipClaimsValidation: true,
}
token, err := p.ParseWithClaims(nerdToken, &payload.NerdClaims{}, func(token *jwt.Token) (interface{}, error) {
if _, ok := token.Method.(*jwt.SigningMethodECDSA); !ok {
return nil, errors.Errorf("Unexpected signing method: %v, expected ECDSA", token.Header["alg"])
}
return key, nil
})
if err != nil {
return nil, errors.Wrapf(err, "failed to parse nerd token '%v'", nerdToken)
}
if !token.Valid {
return nil, errors.Errorf("nerd token '%v' signature is invalid", nerdToken)
}
if claims, ok := token.Claims.(*payload.NerdClaims); ok {
return claims, nil
}
return nil, errors.Errorf("could not decode nerd token '%v'", nerdToken)
}
//ParseECDSAPublicKeyFromPemBytes returns an ECDSA public key from pem bytes
func ParseECDSAPublicKeyFromPemBytes(pemb []byte) (*ecdsa.PublicKey, error) {
block, _ := pem.Decode(pemb)
if block == nil {
return nil, errors.New("failed to parse PEM block containing the public key")
}
pub, err := x509.ParsePKIXPublicKey(block.Bytes)
if err != nil {
return nil, errors.Wrap(err, "failed to parse")
}
switch pub := pub.(type) {
case *ecdsa.PublicKey:
return pub, nil
default:
return nil, errors.New("pem bytes doesn't contain a ECDSA public key")
}
}