Improvements to Session State code (#536)

* Drop SessionStateJSON wrapper
* Use EncrpytInto/DecryptInto to reduce sessionstate

Co-authored-by: Henry Jenkins <henry@henryjenkins.name>

pkg/encryption/cipher.go

@@ -156,3 +156,30 @@ func (c *Cipher) Decrypt(s string) (string, error) {
 
 	return string(encrypted), nil
 }
+
+// EncryptInto encrypts the value and stores it back in the string pointer
+func (c *Cipher) EncryptInto(s *string) error {
+	return into(c.Encrypt, s)
+}
+
+// DecryptInto decrypts the value and stores it back in the string pointer
+func (c *Cipher) DecryptInto(s *string) error {
+	return into(c.Decrypt, s)
+}
+
+// codecFunc is a function that takes a string and encodes/decodes it
+type codecFunc func(string) (string, error)
+
+func into(f codecFunc, s *string) error {
+	// Do not encrypt/decrypt nil or empty strings
+	if s == nil || *s == "" {
+		return nil
+	}
+
+	d, err := f(*s)
+	if err != nil {
+		return err
+	}
+	*s = d
+	return nil
+}

pkg/encryption/cipher_test.go

@@ -133,3 +133,25 @@ func TestEncodeAndDecodeAccessTokenB64(t *testing.T) {
 	assert.NotEqual(t, token, encoded)
 	assert.Equal(t, token, decoded)
 }
+
+func TestEncodeIntoAndDecodeIntoAccessToken(t *testing.T) {
+	const secret = "0123456789abcdefghijklmnopqrstuv"
+	c, err := NewCipher([]byte(secret))
+	assert.Equal(t, nil, err)
+
+	token := "my access token"
+	originalToken := token
+
+	assert.Equal(t, nil, c.EncryptInto(&token))
+	assert.NotEqual(t, originalToken, token)
+
+	assert.Equal(t, nil, c.DecryptInto(&token))
+	assert.Equal(t, originalToken, token)
+
+	// Check no errors with empty or nil strings
+	empty := ""
+	assert.Equal(t, nil, c.EncryptInto(&empty))
+	assert.Equal(t, nil, c.DecryptInto(&empty))
+	assert.Equal(t, nil, c.EncryptInto(nil))
+	assert.Equal(t, nil, c.DecryptInto(nil))
+}