return signature from refund API

src/include/taler_exchange_service.h

@@ -850,22 +850,23 @@ struct TALER_EXCHANGE_RefundHandle;
  * @param cls closure
  * @param hr HTTP response data
  * @param sign_key exchange key used to sign @a obj, or NULL
+ * @param signature the actual signature, or NULL on error
  */
 typedef void
 (*TALER_EXCHANGE_RefundCallback) (
   void *cls,
   const struct TALER_EXCHANGE_HttpResponse *hr,
-  const struct TALER_ExchangePublicKeyP *sign_key);
+  const struct TALER_ExchangePublicKeyP *sign_key,
+  const struct TALER_ExchangeSignatureP *signature);
 
 
 /**
- * Submit a refund request to the exchange and get the exchange's
+ * Submit a refund request to the exchange and get the exchange's response.
- * response.  This API is used by a merchant.  Note that
+ * This API is used by a merchant.  Note that while we return the response
- * while we return the response verbatim to the caller for further
+ * verbatim to the caller for further processing, we do already verify that
- * processing, we do already verify that the response is well-formed
+ * the response is well-formed (i.e. that signatures included in the response
- * (i.e. that signatures included in the response are all valid).  If
+ * are all valid).  If the exchange's reply is not well-formed, we return an
- * the exchange's reply is not well-formed, we return an HTTP status code
+ * HTTP status code of zero to @a cb.
- * of zero to @a cb.
  *
  * The @a exchange must be ready to operate (i.e.  have
  * finished processing the /keys reply).  If this check fails, we do
@@ -913,6 +914,8 @@ TALER_EXCHANGE_refund (struct TALER_EXCHANGE_Handle *exchange,
  * finished processing the /keys reply).  If this check fails, we do
  * NOT initiate the transaction with the exchange and instead return NULL.
  *
+ * FIXME: We can probably DEPRECATE this API and only use #TALER_EXCHANGE_refund()!
+ *
  * @param exchange the exchange handle; the exchange must be ready to operate
  * @param amount the amount to be refunded; must be larger than the refund fee
  *        (as that fee is still being subtracted), and smaller than the amount

src/lib/exchange_api_refund.c

@@ -84,17 +84,19 @@ struct TALER_EXCHANGE_RefundHandle
  * @param rh refund handle
  * @param json json reply with the signature
  * @param[out] exchange_pub set to the exchange's public key
+ * @param[out] exchange_sig set to the exchange's signature
  * @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
  */
 static int
 verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
                             const json_t *json,
-                            struct TALER_ExchangePublicKeyP *exchange_pub)
+                            struct TALER_ExchangePublicKeyP *exchange_pub,
+                            struct TALER_ExchangeSignatureP *exchange_sig)
+
 {
-  struct TALER_ExchangeSignatureP exchange_sig;
   const struct TALER_EXCHANGE_Keys *key_state;
   struct GNUNET_JSON_Specification spec[] = {
-    GNUNET_JSON_spec_fixed_auto ("sig", &exchange_sig),
+    GNUNET_JSON_spec_fixed_auto ("sig", exchange_sig),
     GNUNET_JSON_spec_fixed_auto ("pub", exchange_pub),
     GNUNET_JSON_spec_end ()
   };
@@ -118,7 +120,7 @@ verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
   if (GNUNET_OK !=
       GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_REFUND,
                                   &rh->depconf,
-                                  &exchange_sig.eddsa_signature,
+                                  &exchange_sig->eddsa_signature,
                                   &exchange_pub->eddsa_pub))
   {
     GNUNET_break_op (0);
@@ -143,7 +145,9 @@ handle_refund_finished (void *cls,
 {
   struct TALER_EXCHANGE_RefundHandle *rh = cls;
   struct TALER_ExchangePublicKeyP exchange_pub;
+  struct TALER_ExchangeSignatureP exchange_sig;
   struct TALER_ExchangePublicKeyP *ep = NULL;
+  struct TALER_ExchangeSignatureP *es = NULL;
   const json_t *j = response;
   struct TALER_EXCHANGE_HttpResponse hr = {
     .reply = j,
@@ -160,7 +164,8 @@ handle_refund_finished (void *cls,
     if (GNUNET_OK !=
         verify_refund_signature_ok (rh,
                                     j,
-                                    &exchange_pub))
+                                    &exchange_pub,
+                                    &exchange_sig))
     {
       GNUNET_break_op (0);
       hr.http_status = 0;
@@ -169,6 +174,7 @@ handle_refund_finished (void *cls,
     else
     {
       ep = &exchange_pub;
+      es = &exchange_sig;
     }
     break;
   case MHD_HTTP_BAD_REQUEST:
@@ -227,7 +233,8 @@ handle_refund_finished (void *cls,
   }
   rh->cb (rh->cb_cls,
           &hr,
-          ep);
+          ep,
+          es);
   TALER_EXCHANGE_refund_cancel (rh);
 }
 

src/testing/testing_api_cmd_refund.c

@@ -83,11 +83,13 @@ struct RefundState
  * @param hr HTTP response details
  * @param exchange_pub public key the exchange
  *        used for signing @a obj.
+ * @param exchange_sig actual signature confirming the refund
  */
 static void
 refund_cb (void *cls,
            const struct TALER_EXCHANGE_HttpResponse *hr,
-           const struct TALER_ExchangePublicKeyP *exchange_pub)
+           const struct TALER_ExchangePublicKeyP *exchange_pub,
+           const struct TALER_ExchangeSignatureP *exchange_sig)
 {
 
   struct RefundState *rs = cls;