-API work

src/include/taler_exchange_service.h

@@ -1392,6 +1392,12 @@ struct TALER_EXCHANGE_WithdrawResponse
        * Signature over the coin.
        */
       struct TALER_DenominationSignature sig;
+
+      /**
+       * Values contributed from the exchange during the
+       * withdraw protocol.
+       */
+      struct TALER_ExchangeWithdrawValues exchange_vals;
     } success;
 
     /**
@@ -1664,7 +1670,8 @@ TALER_EXCHANGE_melt_cancel (struct TALER_EXCHANGE_MeltHandle *mh);
  *
  * @param cls closure
  * @param hr HTTP response data
- * @param num_coins number of fresh coins created, length of the @a sigs and @a coin_privs arrays, 0 if the operation failed
+ * @param num_coins number of fresh coins created, length of the @a exchange_vals, @a sigs and @a coin_privs arrays, 0 if the operation failed
+ * @param exchange_vals array of contributions from the exchange on the refreshes
  * @param coin_privs array of @a num_coins private keys for the coins that were created, NULL on error
  * @param sigs array of signature over @a num_coins coins, NULL on error
  */
@@ -1674,6 +1681,7 @@ typedef void
   const struct TALER_EXCHANGE_HttpResponse *hr,
   unsigned int num_coins,
   const struct TALER_CoinSpendPrivateKeyP *coin_privs,
+  const struct TALER_ExchangeWithdrawValues *exchange_vals,
   const struct TALER_DenominationSignature *sigs);
 
 
@@ -2126,6 +2134,7 @@ typedef void
  * @param exchange the exchange handle; the exchange must be ready to operate
  * @param pk kind of coin to pay back
  * @param denom_sig signature over the coin by the exchange using @a pk
+ * @param exchange_vals contribution from the exchange on the withdraw
  * @param ps secret internals of the original planchet
  * @param recoup_cb the callback to call when the final result for this request is available
  * @param recoup_cb_cls closure for @a recoup_cb
@@ -2137,6 +2146,7 @@ struct TALER_EXCHANGE_RecoupHandle *
 TALER_EXCHANGE_recoup (struct TALER_EXCHANGE_Handle *exchange,
                        const struct TALER_EXCHANGE_DenomPublicKey *pk,
                        const struct TALER_DenominationSignature *denom_sig,
+                       const struct TALER_ExchangeWithdrawValues *exchange_vals,
                        const struct TALER_PlanchetSecretsP *ps,
                        TALER_EXCHANGE_RecoupResultCallback recoup_cb,
                        void *recoup_cb_cls);
@@ -2186,6 +2196,7 @@ typedef void
  * @param exchange the exchange handle; the exchange must be ready to operate
  * @param pk kind of coin to pay back
  * @param denom_sig signature over the coin by the exchange using @a pk
+ * @param exchange_vals contribution from the exchange on the withdraw
  * @param ps secret internals of the original refresh-reveal operation
  * @param recoup_cb the callback to call when the final result for this request is available
  * @param recoup_cb_cls closure for @a recoup_cb
@@ -2198,6 +2209,7 @@ TALER_EXCHANGE_recoup_refresh (
   struct TALER_EXCHANGE_Handle *exchange,
   const struct TALER_EXCHANGE_DenomPublicKey *pk,
   const struct TALER_DenominationSignature *denom_sig,
+  const struct TALER_ExchangeWithdrawValues *exchange_vals,
   const struct TALER_PlanchetSecretsP *ps,
   TALER_EXCHANGE_RecoupRefreshResultCallback recoup_cb,
   void *recoup_cb_cls);

src/lib/exchange_api_melt.c

@@ -427,7 +427,8 @@ handle_melt_finished (void *cls,
 
 struct TALER_EXCHANGE_MeltHandle *
 TALER_EXCHANGE_melt (struct TALER_EXCHANGE_Handle *exchange,
-                     const json_t *refresh_data,
+                     const struct TALER_PlanchetSecretsP *ps,
+                     const struct TALER_EXCHANGE_RefreshData *rd,
                      TALER_EXCHANGE_MeltCallback melt_cb,
                      void *melt_cb_cls)
 {
@@ -445,9 +446,10 @@ TALER_EXCHANGE_melt (struct TALER_EXCHANGE_Handle *exchange,
 
   GNUNET_assert (GNUNET_YES ==
                  TEAH_handle_is_ready (exchange));
-  md = TALER_EXCHANGE_deserialize_melt_data_ (refresh_data,
+  if (GNUNET_OK !=
-                                              exchange->key_data.currency);
+      TALER_EXCHANGE_get_melt_data (ps,
-  if (NULL == md)
+                                    rd,
+                                    &md))
   {
     GNUNET_break (0);
     return NULL;
@@ -510,6 +512,7 @@ TALER_EXCHANGE_melt (struct TALER_EXCHANGE_Handle *exchange,
   if (NULL == mh->url)
   {
     json_decref (melt_obj);
+    TALER_EXCHANGE_free_melt_data_ (&md);
     GNUNET_free (mh);
     return NULL;
   }
@@ -523,6 +526,7 @@ TALER_EXCHANGE_melt (struct TALER_EXCHANGE_Handle *exchange,
     GNUNET_break (0);
     if (NULL != eh)
       curl_easy_cleanup (eh);
+    TALER_EXCHANGE_free_melt_data_ (&md);
     json_decref (melt_obj);
     GNUNET_free (mh->url);
     GNUNET_free (mh);

src/lib/exchange_api_refresh_common.c

@@ -23,24 +23,11 @@
 #include "exchange_api_refresh_common.h"
 
 
-/**
- * Free all information associated with a melted coin session.
- *
- * @param mc melted coin to release, the pointer itself is NOT
- *           freed (as it is typically not allocated by itself)
- */
-static void
-free_melted_coin (struct MeltedCoin *mc)
-{
-  TALER_denom_pub_free (&mc->pub_key);
-  TALER_denom_sig_free (&mc->sig);
-}
-
-
 void
 TALER_EXCHANGE_free_melt_data_ (struct MeltData *md)
 {
-  free_melted_coin (&md->melted_coin);
+  TALER_denom_pub_free (&md->melted_coin.pub_key);
+  TALER_denom_sig_free (&md->melted_coin.sig);
   if (NULL != md->fresh_pks)
   {
     for (unsigned int i = 0; i<md->num_fresh_coins; i++)
@@ -55,296 +42,11 @@ TALER_EXCHANGE_free_melt_data_ (struct MeltData *md)
 }
 
 
-/**
+enum GNUNET_GenericReturnValue
- * Serialize information about a coin we are melting.
+TALER_EXCHANGE_get_melt_data_ (
- *
+  const struct TALER_PlanchetSecretsP *ps,
- * @param mc information to serialize
+  const struct struct TALER_EXCHANGE_RefreshData *rd,
- * @return NULL on error
+  struct MeltData *md)
- */
-static json_t *
-serialize_melted_coin (const struct MeltedCoin *mc)
-{
-  json_t *tprivs;
-
-  tprivs = json_array ();
-  GNUNET_assert (NULL != tprivs);
-  for (unsigned int i = 0; i<TALER_CNC_KAPPA; i++)
-    GNUNET_assert (0 ==
-                   json_array_append_new (
-                     tprivs,
-                     GNUNET_JSON_PACK (
-                       GNUNET_JSON_pack_data_auto (
-                         "transfer_priv",
-                         &mc->transfer_priv[i]))));
-  return GNUNET_JSON_PACK (
-    GNUNET_JSON_pack_data_auto ("coin_priv",
-                                &mc->coin_priv),
-    TALER_JSON_pack_denom_sig ("denom_sig",
-                               &mc->sig),
-    TALER_JSON_pack_denom_pub ("denom_pub",
-                               &mc->pub_key),
-    TALER_JSON_pack_amount ("melt_amount_with_fee",
-                            &mc->melt_amount_with_fee),
-    TALER_JSON_pack_amount ("original_value",
-                            &mc->original_value),
-    TALER_JSON_pack_amount ("melt_fee",
-                            &mc->fee_melt),
-    GNUNET_JSON_pack_timestamp ("expire_deposit",
-                                mc->expire_deposit),
-    GNUNET_JSON_pack_array_steal ("transfer_privs",
-                                  tprivs));
-}
-
-
-/**
- * Deserialize information about a coin we are melting.
- *
- * @param[out] mc information to deserialize
- * @param currency expected currency
- * @param in JSON object to read data from
- * @return #GNUNET_NO to report errors
- */
-static enum GNUNET_GenericReturnValue
-deserialize_melted_coin (struct MeltedCoin *mc,
-                         const char *currency,
-                         const json_t *in)
-{
-  json_t *trans_privs;
-  struct GNUNET_JSON_Specification spec[] = {
-    GNUNET_JSON_spec_fixed_auto ("coin_priv",
-                                 &mc->coin_priv),
-    TALER_JSON_spec_denom_sig ("denom_sig",
-                               &mc->sig),
-    TALER_JSON_spec_denom_pub ("denom_pub",
-                               &mc->pub_key),
-    TALER_JSON_spec_amount ("melt_amount_with_fee",
-                            currency,
-                            &mc->melt_amount_with_fee),
-    TALER_JSON_spec_amount ("original_value",
-                            currency,
-                            &mc->original_value),
-    TALER_JSON_spec_amount ("melt_fee",
-                            currency,
-                            &mc->fee_melt),
-    GNUNET_JSON_spec_timestamp ("expire_deposit",
-                                &mc->expire_deposit),
-    GNUNET_JSON_spec_json ("transfer_privs",
-                           &trans_privs),
-    GNUNET_JSON_spec_end ()
-  };
-
-  if (GNUNET_OK !=
-      GNUNET_JSON_parse (in,
-                         spec,
-                         NULL, NULL))
-  {
-    GNUNET_break_op (0);
-    return GNUNET_NO;
-  }
-  if (TALER_CNC_KAPPA != json_array_size (trans_privs))
-  {
-    GNUNET_JSON_parse_free (spec);
-    GNUNET_break_op (0);
-    return GNUNET_NO;
-  }
-  for (unsigned int i = 0; i<TALER_CNC_KAPPA; i++)
-  {
-    struct GNUNET_JSON_Specification spec[] = {
-      GNUNET_JSON_spec_fixed_auto ("transfer_priv",
-                                   &mc->transfer_priv[i]),
-      GNUNET_JSON_spec_end ()
-    };
-
-    if (GNUNET_OK !=
-        GNUNET_JSON_parse (json_array_get (trans_privs,
-                                           i),
-                           spec,
-                           NULL, NULL))
-    {
-      GNUNET_break_op (0);
-      GNUNET_JSON_parse_free (spec);
-      return GNUNET_NO;
-    }
-  }
-  json_decref (trans_privs);
-  return GNUNET_OK;
-}
-
-
-/**
- * Serialize melt data.
- *
- * @param md data to serialize
- * @return serialized melt data
- */
-static json_t *
-serialize_melt_data (const struct MeltData *md)
-{
-  json_t *fresh_coins;
-
-  fresh_coins = json_array ();
-  GNUNET_assert (NULL != fresh_coins);
-  for (int i = 0; i<md->num_fresh_coins; i++)
-  {
-    json_t *planchet_secrets;
-
-    planchet_secrets = json_array ();
-    GNUNET_assert (NULL != planchet_secrets);
-    for (unsigned int j = 0; j<TALER_CNC_KAPPA; j++)
-    {
-      json_t *ps;
-
-      ps = GNUNET_JSON_PACK (
-        GNUNET_JSON_pack_data_auto ("ps",
-                                    &md->fresh_coins[j][i]));
-      GNUNET_assert (0 ==
-                     json_array_append_new (planchet_secrets,
-                                            ps));
-    }
-    GNUNET_assert (0 ==
-                   json_array_append_new (
-                     fresh_coins,
-                     GNUNET_JSON_PACK (
-                       TALER_JSON_pack_denom_pub ("denom_pub",
-                                                  &md->fresh_pks[i]),
-                       GNUNET_JSON_pack_array_steal ("planchet_secrets",
-                                                     planchet_secrets)))
-                   );
-  }
-  return GNUNET_JSON_PACK (
-    GNUNET_JSON_pack_array_steal ("fresh_coins",
-                                  fresh_coins),
-    GNUNET_JSON_pack_object_steal ("melted_coin",
-                                   serialize_melted_coin (&md->melted_coin)),
-    GNUNET_JSON_pack_data_auto ("rc",
-                                &md->rc));
-}
-
-
-struct MeltData *
-TALER_EXCHANGE_deserialize_melt_data_ (const json_t *melt_data,
-                                       const char *currency)
-{
-  struct MeltData *md = GNUNET_new (struct MeltData);
-  json_t *fresh_coins;
-  json_t *melted_coin;
-  struct GNUNET_JSON_Specification spec[] = {
-    GNUNET_JSON_spec_fixed_auto ("rc",
-                                 &md->rc),
-    GNUNET_JSON_spec_json ("melted_coin",
-                           &melted_coin),
-    GNUNET_JSON_spec_json ("fresh_coins",
-                           &fresh_coins),
-    GNUNET_JSON_spec_end ()
-  };
-  bool ok;
-
-  if (GNUNET_OK !=
-      GNUNET_JSON_parse (melt_data,
-                         spec,
-                         NULL, NULL))
-  {
-    GNUNET_break (0);
-    GNUNET_JSON_parse_free (spec);
-    GNUNET_free (md);
-    return NULL;
-  }
-  if (! (json_is_array (fresh_coins) &&
-         json_is_object (melted_coin)) )
-  {
-    GNUNET_break (0);
-    GNUNET_JSON_parse_free (spec);
-    return NULL;
-  }
-  if (GNUNET_OK !=
-      deserialize_melted_coin (&md->melted_coin,
-                               currency,
-                               melted_coin))
-  {
-    GNUNET_break (0);
-    GNUNET_JSON_parse_free (spec);
-    return NULL;
-  }
-  md->num_fresh_coins = json_array_size (fresh_coins);
-  md->fresh_pks = GNUNET_new_array (md->num_fresh_coins,
-                                    struct TALER_DenominationPublicKey);
-  for (unsigned int i = 0; i<TALER_CNC_KAPPA; i++)
-    md->fresh_coins[i] = GNUNET_new_array (md->num_fresh_coins,
-                                           struct TALER_PlanchetSecretsP);
-  ok = true;
-  for (unsigned int i = 0; i<md->num_fresh_coins; i++)
-  {
-    const json_t *ji = json_array_get (fresh_coins,
-                                       i);
-    json_t *planchet_secrets;
-    struct GNUNET_JSON_Specification ispec[] = {
-      GNUNET_JSON_spec_json ("planchet_secrets",
-                             &planchet_secrets),
-      TALER_JSON_spec_denom_pub ("denom_pub",
-                                 &md->fresh_pks[i]),
-      GNUNET_JSON_spec_end ()
-    };
-
-    if (GNUNET_OK !=
-        GNUNET_JSON_parse (ji,
-                           ispec,
-                           NULL, NULL))
-    {
-      GNUNET_break (0);
-      ok = false;
-      break;
-    }
-    if ( (! json_is_array (planchet_secrets)) ||
-         (TALER_CNC_KAPPA != json_array_size (planchet_secrets)) )
-    {
-      GNUNET_break (0);
-      ok = false;
-      GNUNET_JSON_parse_free (ispec);
-      break;
-    }
-    for (unsigned int j = 0; j<TALER_CNC_KAPPA; j++)
-    {
-      struct GNUNET_JSON_Specification jspec[] = {
-        GNUNET_JSON_spec_fixed_auto ("ps",
-                                     &md->fresh_coins[j][i]),
-        GNUNET_JSON_spec_end ()
-      };
-
-      if (GNUNET_OK !=
-          GNUNET_JSON_parse (json_array_get (planchet_secrets,
-                                             j),
-                             jspec,
-                             NULL, NULL))
-      {
-        GNUNET_break (0);
-        ok = false;
-        break;
-      }
-    }
-    json_decref (planchet_secrets);
-    if (! ok)
-      break;
-  }
-
-  GNUNET_JSON_parse_free (spec);
-  if (! ok)
-  {
-    TALER_EXCHANGE_free_melt_data_ (md);
-    GNUNET_free (md);
-    return NULL;
-  }
-  return md;
-}
-
-
-json_t *
-TALER_EXCHANGE_refresh_prepare (
-  const struct TALER_CoinSpendPrivateKeyP *melt_priv,
-  const struct TALER_Amount *melt_amount,
-  const struct TALER_DenominationSignature *melt_sig,
-  const struct TALER_EXCHANGE_DenomPublicKey *melt_pk,
-  unsigned int fresh_pks_len,
-  const struct TALER_EXCHANGE_DenomPublicKey *fresh_pks)
 {
   struct MeltData md;
   json_t *ret;
@@ -359,68 +61,68 @@ TALER_EXCHANGE_refresh_prepare (
   memset (&md,
           0,
           sizeof (md));
-  md.num_fresh_coins = fresh_pks_len;
+  md.num_fresh_coins = rd->fresh_pks_len;
-  md.melted_coin.coin_priv = *melt_priv;
+  md.melted_coin.coin_priv = rd->melt_priv;
-  md.melted_coin.melt_amount_with_fee = *melt_amount;
+  md.melted_coin.melt_amount_with_fee = rd->melt_amount;
-  md.melted_coin.fee_melt = melt_pk->fee_refresh;
+  md.melted_coin.fee_melt = rd->melt_pk->fee_refresh;
-  md.melted_coin.original_value = melt_pk->value;
+  md.melted_coin.original_value = rd->melt_pk->value;
-  md.melted_coin.expire_deposit
+  md.melted_coin.expire_deposit = rd->melt_pk->expire_deposit;
-    = melt_pk->expire_deposit;
   GNUNET_assert (GNUNET_OK ==
                  TALER_amount_set_zero (melt_amount->currency,
                                         &total));
   TALER_denom_pub_deep_copy (&md.melted_coin.pub_key,
-                             &melt_pk->key);
+                             &rd->melt_pk->key);
   TALER_denom_sig_deep_copy (&md.melted_coin.sig,
-                             melt_sig);
+                             rd->melt_sig);
-  md.fresh_pks = GNUNET_new_array (fresh_pks_len,
+  md.fresh_pks = GNUNET_new_array (rd->fresh_pks_len,
                                    struct TALER_DenominationPublicKey);
-  for (unsigned int i = 0; i<fresh_pks_len; i++)
+  for (unsigned int i = 0; i<rd->fresh_pks_len; i++)
   {
     TALER_denom_pub_deep_copy (&md.fresh_pks[i],
                                &fresh_pks[i].key);
     if ( (0 >
           TALER_amount_add (&total,
                             &total,
-                            &fresh_pks[i].value)) ||
+                            &rd->fresh_pks[i].value)) ||
          (0 >
           TALER_amount_add (&total,
                             &total,
-                            &fresh_pks[i].fee_withdraw)) )
+                            &rd->fresh_pks[i].fee_withdraw)) )
     {
       GNUNET_break (0);
       TALER_EXCHANGE_free_melt_data_ (&md);
-      return NULL;
+      return GNUNET_SYSERR;
     }
   }
   /* verify that melt_amount is above total cost */
   if (1 ==
       TALER_amount_cmp (&total,
-                        melt_amount) )
+                        rd->melt_amount) )
   {
     /* Eh, this operation is more expensive than the
        @a melt_amount. This is not OK. */
     GNUNET_break (0);
     TALER_EXCHANGE_free_melt_data_ (&md);
-    return NULL;
+    return GNUNET_SYSERR;
   }
 
   /* build up coins */
   for (unsigned int i = 0; i<TALER_CNC_KAPPA; i++)
   {
+    // FIXME: derive!
     GNUNET_CRYPTO_ecdhe_key_create (
       &md.melted_coin.transfer_priv[i].ecdhe_priv);
     GNUNET_CRYPTO_ecdhe_key_get_public (
       &md.melted_coin.transfer_priv[i].ecdhe_priv,
       &rce[i].transfer_pub.ecdhe_pub);
-    TALER_link_derive_transfer_secret  (melt_priv,
+    TALER_link_derive_transfer_secret (&rd->melt_priv,
-                                        &md.melted_coin.transfer_priv[i],
+                                       &md.melted_coin.transfer_priv[i],
-                                        &trans_sec[i]);
+                                       &trans_sec[i]);
-    md.fresh_coins[i] = GNUNET_new_array (fresh_pks_len,
+    md.fresh_coins[i] = GNUNET_new_array (rd->fresh_pks_len,
                                           struct TALER_PlanchetSecretsP);
-    rce[i].new_coins = GNUNET_new_array (fresh_pks_len,
+    rce[i].new_coins = GNUNET_new_array (rd->fresh_pks_len,
                                          struct TALER_RefreshCoinData);
-    for (unsigned int j = 0; j<fresh_pks_len; j++)
+    for (unsigned int j = 0; j<rd->fresh_pks_len; j++)
     {
       struct TALER_PlanchetSecretsP *fc = &md.fresh_coins[i][j];
       struct TALER_RefreshCoinData *rcd = &rce[i].new_coins[j];
@@ -458,15 +160,12 @@ TALER_EXCHANGE_refresh_prepare (
                                 fresh_pks_len,
                                 rce,
                                 &coin_pub,
-                                melt_amount);
+                                &rd->melt_amount);
-  /* finally, serialize everything */
-  ret = serialize_melt_data (&md);
   for (unsigned int i = 0; i < TALER_CNC_KAPPA; i++)
   {
     for (unsigned int j = 0; j < fresh_pks_len; j++)
       GNUNET_free (rce[i].new_coins[j].coin_ev);
     GNUNET_free (rce[i].new_coins);
   }
-  TALER_EXCHANGE_free_melt_data_ (&md);
+  return GNUNET_OK;
-  return ret;
 }

src/lib/exchange_api_refresh_common.h

@@ -111,15 +111,17 @@ struct MeltData
 
 
 /**
- * Deserialize melt data.
+ * Compute the melt data from the refresh data and secret.
  *
- * @param data json data to deserialize
+ * @param ps secret internals of the refresh-reveal operation
- * @param currency expected currency for the coins
+ * @param rd refresh data with the characteristics of the operation
- * @return deserialized melt data, NULL on error
+ * @param[out] rd where to write the derived melt data
  */
-struct MeltData *
+enum GNUNET_GenericReturnValue
-TALER_EXCHANGE_deserialize_melt_data_ (const json_t *data,
+TALER_EXCHANGE_get_melt_data_ (
-                                       const char *currency);
+  const struct TALER_PlanchetSecretsP *ps,
+  const struct struct TALER_EXCHANGE_RefreshData *rd,
+  struct MeltData *md);
 
 
 /**

src/lib/exchange_api_refreshes_reveal.c

@@ -73,7 +73,7 @@ struct TALER_EXCHANGE_RefreshesRevealHandle
   /**
    * Actual information about the melt operation.
    */
-  struct MeltData *md;
+  struct MeltData md;
 
   /**
    * The index selected by the exchange in cut-and-choose to not be revealed.
@@ -298,7 +298,8 @@ handle_refresh_reveal_finished (void *cls,
 struct TALER_EXCHANGE_RefreshesRevealHandle *
 TALER_EXCHANGE_refreshes_reveal (
   struct TALER_EXCHANGE_Handle *exchange,
-  const json_t *refresh_data,
+  const struct TALER_PlanchetSecretsP *ps,
+  const struct TALER_EXCHANGE_RefreshData *rd,
   uint32_t noreveal_index,
   TALER_EXCHANGE_RefreshesRevealCallback reveal_cb,
   void *reveal_cb_cls)
@@ -311,7 +312,7 @@ TALER_EXCHANGE_refreshes_reveal (
   json_t *link_sigs;
   CURL *eh;
   struct GNUNET_CURL_Context *ctx;
-  struct MeltData *md;
+  struct MeltData md;
   struct TALER_TransferPublicKeyP transfer_pub;
   char arg_str[sizeof (struct TALER_RefreshCommitmentP) * 2 + 32];
 
@@ -330,9 +331,10 @@ TALER_EXCHANGE_refreshes_reveal (
     GNUNET_break (0);
     return NULL;
   }
-  md = TALER_EXCHANGE_deserialize_melt_data_ (refresh_data,
+  if (GNUNET_OK !=
-                                              exchange->key_data.currency);
+      TALER_EXCHANGE_get_melt_data (ps,
-  if (NULL == md)
+                                    rd,
+                                    &md))
   {
     GNUNET_break (0);
     return NULL;
@@ -340,21 +342,21 @@ TALER_EXCHANGE_refreshes_reveal (
 
   /* now transfer_pub */
   GNUNET_CRYPTO_ecdhe_key_get_public (
-    &md->melted_coin.transfer_priv[noreveal_index].ecdhe_priv,
+    &md.melted_coin.transfer_priv[noreveal_index].ecdhe_priv,
     &transfer_pub.ecdhe_pub);
 
   /* now new_denoms */
   GNUNET_assert (NULL != (new_denoms_h = json_array ()));
   GNUNET_assert (NULL != (coin_evs = json_array ()));
   GNUNET_assert (NULL != (link_sigs = json_array ()));
-  for (unsigned int i = 0; i<md->num_fresh_coins; i++)
+  for (unsigned int i = 0; i<md.num_fresh_coins; i++)
   {
     struct TALER_DenominationHash denom_hash;
     struct TALER_ExchangeWithdrawValues alg_values;
     struct TALER_PlanchetDetail pd;
     struct TALER_CoinPubHash c_hash;
 
-    TALER_denom_pub_hash (&md->fresh_pks[i],
+    TALER_denom_pub_hash (&md.fresh_pks[i],
                           &denom_hash);
     GNUNET_assert (0 ==
                    json_array_append_new (new_denoms_h,
@@ -364,9 +366,9 @@ TALER_EXCHANGE_refreshes_reveal (
     // TODO: implement cipher handling
     alg_values.cipher = TALER_DENOMINATION_RSA;
     if (GNUNET_OK !=
-        TALER_planchet_prepare (&md->fresh_pks[i],
+        TALER_planchet_prepare (&md.fresh_pks[i],
                                 &alg_values,
-                                &md->fresh_coins[noreveal_index][i],
+                                &md.fresh_coins[noreveal_index][i],
                                 &c_hash,
                                 &pd))
     {
@@ -374,6 +376,7 @@ TALER_EXCHANGE_refreshes_reveal (
       GNUNET_break (0);
       json_decref (new_denoms_h);
       json_decref (coin_evs);
+      TALER_EXCHANGE_free_melt_data_ (&md);
       return NULL;
     }
     GNUNET_assert (0 ==
@@ -394,7 +397,7 @@ TALER_EXCHANGE_refreshes_reveal (
                               blinded_msg,
                               pd.blinded_planchet.details.rsa_blinded_planchet.
                               blinded_msg_size,
-                              &md->melted_coin.coin_priv,
+                              &md.melted_coin.coin_priv,
                               &link_sig);
       GNUNET_assert (0 ==
                      json_array_append_new (
@@ -417,7 +420,7 @@ TALER_EXCHANGE_refreshes_reveal (
     GNUNET_assert (0 ==
                    json_array_append_new (transfer_privs,
                                           GNUNET_JSON_from_data_auto (
-                                            &md->melted_coin.transfer_priv[j])));
+                                            &md.melted_coin.transfer_priv[j])));
   }
 
   /* build main JSON request */
@@ -436,7 +439,7 @@ TALER_EXCHANGE_refreshes_reveal (
     char pub_str[sizeof (struct TALER_RefreshCommitmentP) * 2];
     char *end;
 
-    end = GNUNET_STRINGS_data_to_string (&md->rc,
+    end = GNUNET_STRINGS_data_to_string (&md.rc,
                                          sizeof (struct
                                                  TALER_RefreshCommitmentP),
                                          pub_str,
@@ -459,6 +462,7 @@ TALER_EXCHANGE_refreshes_reveal (
   if (NULL == rrh->url)
   {
     json_decref (reveal_obj);
+    TALER_EXCHANGE_free_melt_data_ (&md);
     GNUNET_free (rrh);
     return NULL;
   }
@@ -473,6 +477,7 @@ TALER_EXCHANGE_refreshes_reveal (
     if (NULL != eh)
       curl_easy_cleanup (eh);
     json_decref (reveal_obj);
+    TALER_EXCHANGE_free_melt_data_ (&md);
     GNUNET_free (rrh->url);
     GNUNET_free (rrh);
     return NULL;