lego/acme/jws.go
Pavel Forkert d149f14b6b Properly lock jws.nonces (#319)
Before read access to `nonces` field in jws structure (in `Nonces` method) was not synchronized and we were still able
to get `slice bounds out of range` panic when trying to "pop" value in `Nonces` method.

The race can be actually observed by running `Nonce` method multiple times in separate goroutines with th precondition is `len(jws.nonces) == 1`.
2016-12-13 09:49:37 +01:00

115 lines
2.2 KiB
Go

package acme
import (
"bytes"
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rsa"
"fmt"
"net/http"
"sync"
"gopkg.in/square/go-jose.v1"
)
type jws struct {
directoryURL string
privKey crypto.PrivateKey
nonces []string
sync.Mutex
}
func keyAsJWK(key interface{}) *jose.JsonWebKey {
switch k := key.(type) {
case *ecdsa.PublicKey:
return &jose.JsonWebKey{Key: k, Algorithm: "EC"}
case *rsa.PublicKey:
return &jose.JsonWebKey{Key: k, Algorithm: "RSA"}
default:
return nil
}
}
// Posts a JWS signed message to the specified URL
func (j *jws) post(url string, content []byte) (*http.Response, error) {
signedContent, err := j.signContent(content)
if err != nil {
return nil, err
}
resp, err := httpPost(url, "application/jose+json", bytes.NewBuffer([]byte(signedContent.FullSerialize())))
if err != nil {
return nil, err
}
j.Lock()
defer j.Unlock()
j.getNonceFromResponse(resp)
return resp, err
}
func (j *jws) signContent(content []byte) (*jose.JsonWebSignature, error) {
var alg jose.SignatureAlgorithm
switch k := j.privKey.(type) {
case *rsa.PrivateKey:
alg = jose.RS256
case *ecdsa.PrivateKey:
if k.Curve == elliptic.P256() {
alg = jose.ES256
} else if k.Curve == elliptic.P384() {
alg = jose.ES384
}
}
signer, err := jose.NewSigner(alg, j.privKey)
if err != nil {
return nil, err
}
signer.SetNonceSource(j)
signed, err := signer.Sign(content)
if err != nil {
return nil, err
}
return signed, nil
}
func (j *jws) getNonceFromResponse(resp *http.Response) error {
nonce := resp.Header.Get("Replay-Nonce")
if nonce == "" {
return fmt.Errorf("Server did not respond with a proper nonce header.")
}
j.nonces = append(j.nonces, nonce)
return nil
}
func (j *jws) getNonce() error {
resp, err := httpHead(j.directoryURL)
if err != nil {
return err
}
return j.getNonceFromResponse(resp)
}
func (j *jws) Nonce() (string, error) {
j.Lock()
defer j.Unlock()
nonce := ""
if len(j.nonces) == 0 {
err := j.getNonce()
if err != nil {
return nonce, err
}
}
if len(j.nonces) == 0 {
return "", fmt.Errorf("Can't get nonce")
}
nonce, j.nonces = j.nonces[len(j.nonces)-1], j.nonces[:len(j.nonces)-1]
return nonce, nil
}