add a noise_cipherstate_get_nonce test function

include/noise/protocol/cipherstate.h

@@ -49,6 +49,7 @@ int noise_cipherstate_decrypt_with_ad
 int noise_cipherstate_encrypt(NoiseCipherState *state, NoiseBuffer *buffer);
 int noise_cipherstate_decrypt(NoiseCipherState *state, NoiseBuffer *buffer);
 int noise_cipherstate_set_nonce(NoiseCipherState *state, uint64_t nonce);
+int noise_cipherstate_get_nonce(const NoiseCipherState *state, uint64_t *nonce);
 int noise_cipherstate_get_max_key_length(void);
 int noise_cipherstate_get_max_mac_length(void);
 

src/protocol/cipherstate.c

@@ -534,6 +534,35 @@ int noise_cipherstate_set_nonce(NoiseCipherState *state, uint64_t nonce)
     return NOISE_ERROR_NONE;
 }
 
+/**
+ * \brief Gets the nonce value for this cipherstate object.
+ *
+ * \param state The CipherState object.
+ * \param nonce The nonce value to get.
+ *
+ * \return NOISE_ERROR_NONE on success.
+ * \return NOISE_ERROR_INVALID_PARAM if \a state or \a nonce is NULL.
+ * \return NOISE_ERROR_INVALID_STATE if the key has not been set yet.
+ *
+ * \warning This function is intended for testing purposes only.
+ *
+ * \sa noise_cipherstate_init_key()
+ */
+int noise_cipherstate_get_nonce(const NoiseCipherState *state, uint64_t * nonce)
+{
+    /* Bail out if the state or the nonce is NULL */
+    if (!state || !nonce)
+        return NOISE_ERROR_INVALID_PARAM;
+
+    /* If the key hasn't been set yet, we cannot do this */
+    if (!state->has_key)
+        return NOISE_ERROR_INVALID_STATE;
+
+    /* Set the nonce param and return */
+    *nonce = state->n;
+    return NOISE_ERROR_NONE;
+}
+
 /**
  * \brief Gets the maximum key length for the supported algorithms.
  *