-add missing checkpointing logic

5 files changed, 304 insertions, 76 deletions

diff --git a/src/auditor/taler-helper-auditor-coins.c b/src/auditor/taler-helper-auditor-coins.c
index e33364844..8021b3982 100644
--- a/src/auditor/taler-helper-auditor-coins.c
+++ b/src/auditor/taler-helper-auditor-coins.c
@@ -2350,6 +2350,11 @@ check_denomination (
  * @param cls closure
  * @param rowid unique serial ID for the deposit in our DB
  * @param deposit deposit details
+ * @param reserve_pub which reserve is the purse merged into, NULL if unknown
+ * @param flags purse flags
+ * @param auditor_balance purse balance (according to the
+ *          auditor during auditing)
+ * @param purse_total target amount the purse should reach
  * @param denom_pub denomination public key of @a coin_pub
  * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
  */
@@ -2358,6 +2363,10 @@ purse_deposit_cb (
   void *cls,
   uint64_t rowid,
   const struct TALER_EXCHANGEDB_PurseDeposit *deposit,
+  const struct TALER_ReservePublicKeyP *reserve_pub,
+  enum TALER_WalletAccountMergeFlags flags,
+  const struct TALER_Amount *auditor_balance,
+  const struct TALER_Amount *purse_total,
   const struct TALER_DenominationPublicKey *denom_pub)
 {
   struct CoinContext *cc = cls;
@@ -2366,6 +2375,10 @@ purse_deposit_cb (
   const struct TALER_EXCHANGEDB_DenominationKeyInformation *issue;
   struct DenominationSummary *ds;
 
+  (void) flags;
+  (void) auditor_balance;
+  (void) purse_total;
+  (void) reserve_pub;
   GNUNET_assert (rowid >= ppc.last_purse_deposits_serial_id);
   ppc.last_purse_deposits_serial_id = rowid + 1;
   qs = TALER_ARL_get_denomination_info (denom_pub,
diff --git a/src/auditor/taler-helper-auditor-reserves.c b/src/auditor/taler-helper-auditor-reserves.c
index 49176dcfa..a3976bc9a 100644
--- a/src/auditor/taler-helper-auditor-reserves.c
+++ b/src/auditor/taler-helper-auditor-reserves.c
@@ -70,6 +70,11 @@ static json_t *denomination_key_validity_withdraw_inconsistencies;
 static json_t *report_reserve_balance_insufficient_inconsistencies;
 
 /**
+ * Array of reports about purse balance insufficient inconsitencies.
+ */
+static json_t *report_purse_balance_insufficient_inconsistencies;
+
+/**
  * Total amount reserves were charged beyond their balance.
  */
 static struct TALER_Amount total_balance_insufficient_loss;
@@ -754,12 +759,13 @@ handle_recoup_by_reserve (
       {
         rev = "revoked";
       }
-      GNUNET_assert (GNUNET_OK ==
-                     GNUNET_CONTAINER_multihashmap_put (rc->revoked,
-                                                        &coin->denom_pub_hash.
-                                                        hash,
-                                                        (void *) rev,
-                                                        GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+      GNUNET_assert (
+        GNUNET_OK ==
+        GNUNET_CONTAINER_multihashmap_put (
+          rc->revoked,
+          &coin->denom_pub_hash.hash,
+          (void *) rev,
+          GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
     }
   }
   else
@@ -1255,6 +1261,12 @@ verify_reserve_balance (void *cls,
  * @param cls closure
  * @param rowid unique serial ID for the deposit in our DB
  * @param deposit deposit details
+ * @param reserve_pub which reserve is the purse merged into, NULL if unknown
+ * @param auditor_balance balance of the purse calculated by auditor
+ * @param flags purse flags
+ * @param auditor_balance purse balance (according to the
+ *          auditor during auditing)
+ * @param purse_total target amount the purse should reach
  * @param denom_pub denomination public key of @a coin_pub
  * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
  */
@@ -1263,12 +1275,25 @@ handle_purse_deposits (
   void *cls,
   uint64_t rowid,
   const struct TALER_EXCHANGEDB_PurseDeposit *deposit,
+  const struct TALER_ReservePublicKeyP *reserve_pub,
+  enum TALER_WalletAccountMergeFlags flags,
+  const struct TALER_Amount *auditor_balance,
+  const struct TALER_Amount *purse_total,
   const struct TALER_DenominationPublicKey *denom_pub)
 {
+  struct ReserveContext *rc = cls;
   const char *base_url
     = (NULL == deposit->exchange_base_url)
     ? TALER_ARL_exchange_url
     : deposit->exchange_base_url;
+  enum GNUNET_DB_QueryStatus qs;
+  struct TALER_Amount amount_minus_fee;
+  struct TALER_Amount new_balance;
+  struct ReserveSummary *rs;
+
+  /* should be monotonically increasing */
+  GNUNET_assert (rowid >= ppr.last_purse_deposits_serial_id);
+  ppr.last_purse_deposits_serial_id = rowid + 1;
 
   if (GNUNET_OK !=
       TALER_wallet_purse_deposit_verify (base_url,
@@ -1293,10 +1318,87 @@ handle_purse_deposits (
     return GNUNET_OK;
   }
 
-  GNUNET_break (0); // FIXME
-  // FIXME: need flags + total deposited!
-  /* Credit purse value (if last op)! */
-  return GNUNET_SYSERR;
+  {
+    const struct TALER_EXCHANGEDB_DenominationKeyInformation *issue;
+    enum GNUNET_DB_QueryStatus qs;
+    struct TALER_DenominationHashP h_denom_pub;
+
+    qs = TALER_ARL_get_denomination_info (denom_pub,
+                                          &issue,
+                                          &h_denom_pub);
+    if (0 > qs)
+    {
+      GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
+      if (GNUNET_DB_STATUS_HARD_ERROR == qs)
+        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                    "Hard database error trying to get denomination %s from database!\n",
+                    TALER_B2S (denom_pub));
+      rc->qs = qs;
+      return GNUNET_SYSERR;
+    }
+    if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
+    {
+      report_row_inconsistency ("purse-deposit",
+                                rowid,
+                                "denomination key not found");
+      if (TALER_ARL_do_abort ())
+        return GNUNET_SYSERR;
+      return GNUNET_OK;
+    }
+    TALER_ARL_amount_subtract (&amount_minus_fee,
+                               &deposit->amount,
+                               &issue->fees.deposit);
+  }
+
+  TALER_ARL_amount_add (&new_balance,
+                        auditor_balance,
+                        &amount_minus_fee);
+  qs = TALER_ARL_edb->set_purse_balance (TALER_ARL_edb->cls,
+                                         &deposit->purse_pub,
+                                         &new_balance);
+  GNUNET_assert (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS != qs);
+  if (qs < 0)
+  {
+    GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
+    GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR == qs);
+    rc->qs = qs;
+    return GNUNET_SYSERR;
+  }
+  if (TALER_WAMF_MODE_CREATE_WITH_PURSE_FEE !=
+      (flags & TALER_WAMF_MERGE_MODE_MASK))
+  {
+    /* This just created the purse, actual credit to
+       the reserve will be done in handle_account_merged() */
+    return GNUNET_OK;
+  }
+  if ( (NULL != deposit->exchange_base_url) &&
+       (0 != strcmp (deposit->exchange_base_url,
+                     TALER_ARL_exchange_url)) )
+  {
+    /* credited reserve is at another exchange, do NOT credit here! */
+    return GNUNET_OK;
+  }
+
+  rs = setup_reserve (rc,
+                      reserve_pub);
+  if (NULL == rs)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  if ( (-1 != TALER_amount_cmp (&new_balance,
+                                purse_total)) &&
+       (-1 == TALER_amount_cmp (auditor_balance,
+                                purse_total)) )
+  {
+    /* new balance at or above purse_total
+       (and previous balance was below); thus
+       credit reserve with purse value! */
+    TALER_ARL_amount_add (&rs->total_in,
+                          &rs->total_in,
+                          purse_total);
+  }
+  return GNUNET_OK;
 }
 
 
@@ -1307,6 +1409,15 @@ handle_purse_deposits (
  *
  * @param cls closure
  * @param rowid unique serial ID for the deposit in our DB
+ * @param partner_base_url where is the reserve, NULL for this exchange
+ * @param amount total amount expected in the purse
+ * @param balance current balance in the purse (according to the auditor)
+ * @param flags purse flags
+ * @param merge_pub merge capability key
+ * @param reserve_pub reserve the merge affects
+ * @param merge_sig signature affirming the merge
+ * @param purse_pub purse key
+ * @param merge_timestamp when did the merge happen
  * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
  */
 static enum GNUNET_GenericReturnValue
@@ -1315,6 +1426,7 @@ handle_purse_merged (
   uint64_t rowid,
   const char *partner_base_url,
   const struct TALER_Amount *amount,
+  const struct TALER_Amount *balance,
   enum TALER_WalletAccountMergeFlags flags,
   const struct TALER_PurseMergePublicKeyP *merge_pub,
   const struct TALER_ReservePublicKeyP *reserve_pub,
@@ -1326,6 +1438,9 @@ handle_purse_merged (
   struct ReserveSummary *rs;
   char *reserve_url;
 
+  /* should be monotonically increasing */
+  GNUNET_assert (rowid >= ppr.last_purse_merges_serial_id);
+  ppr.last_purse_merges_serial_id = rowid + 1;
   reserve_url
     = TALER_reserve_make_payto (NULL == partner_base_url
                                 ? TALER_ARL_exchange_url
@@ -1376,10 +1491,34 @@ handle_purse_merged (
     GNUNET_break (0);
     return GNUNET_SYSERR;
   }
+  if (-1 == TALER_amount_cmp (balance,
+                              amount))
+  {
+    struct TALER_Amount loss;
+
+    TALER_ARL_amount_subtract (&loss,
+                               amount,
+                               balance);
+    /* illegal merge, balance is still below total purse value */
+    TALER_ARL_report (report_purse_balance_insufficient_inconsistencies,
+                      GNUNET_JSON_PACK (
+                        GNUNET_JSON_pack_string ("operation",
+                                                 "merge-purse"),
+                        GNUNET_JSON_pack_uint64 ("row",
+                                                 rowid),
+                        TALER_JSON_pack_amount ("loss",
+                                                &loss),
+                        GNUNET_JSON_pack_data_auto ("purse_pub",
+                                                    purse_pub)));
+    TALER_ARL_amount_add (&total_balance_insufficient_loss,
+                          &total_balance_insufficient_loss,
+                          &loss);
+    return GNUNET_OK;
+  }
   TALER_ARL_amount_add (&rs->total_in,
                         &rs->total_in,
                         amount);
-  // rs->a_expiration_date = FIXME: set to what?;
+  // rs->a_expiration_date = FIXME: do we care? If so, set to what (so that the auditor no longer complains about the reserve not being closed)
   return GNUNET_OK;
 }
 
@@ -1411,6 +1550,9 @@ handle_account_merged (
   struct ReserveContext *rc = cls;
   struct ReserveSummary *rs;
 
+  /* should be monotonically increasing */
+  GNUNET_assert (rowid >= ppr.last_account_merges_serial_id);
+  ppr.last_account_merges_serial_id = rowid + 1;
   if (GNUNET_OK !=
       TALER_wallet_account_merge_verify (merge_timestamp,
                                          purse_pub,
@@ -1476,6 +1618,9 @@ handle_history_request (
   struct ReserveContext *rc = cls;
   struct ReserveSummary *rs;
 
+  /* should be monotonically increasing */
+  GNUNET_assert (rowid >= ppr.last_history_requests_serial_id);
+  ppr.last_history_requests_serial_id = rowid + 1;
   if (GNUNET_OK !=
       TALER_wallet_reserve_history_verify (ts,
                                            history_fee,
@@ -1616,17 +1761,6 @@ analyze_reserves (void *cls)
     GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
     return qs;
   }
-  /* Credit purse value (if last op)! */
-  qs = TALER_ARL_edb->select_purse_merges_above_serial_id (
-    TALER_ARL_edb->cls,
-    ppr.last_purse_merges_serial_id,
-    &handle_purse_merged,
-    &rc);
-  if (qs < 0)
-  {
-    GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
-    return qs;
-  }
   qs = TALER_ARL_edb->select_purse_deposits_above_serial_id (
     TALER_ARL_edb->cls,
     ppr.last_purse_deposits_serial_id,
@@ -1648,6 +1782,17 @@ analyze_reserves (void *cls)
     GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
     return qs;
   }
+  /* Credit purse value (if last op)! */
+  qs = TALER_ARL_edb->select_purse_merges_above_serial_id (
+    TALER_ARL_edb->cls,
+    ppr.last_purse_merges_serial_id,
+    &handle_purse_merged,
+    &rc);
+  if (qs < 0)
+  {
+    GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
+    return qs;
+  }
   /* Charge history fee! */
   qs = TALER_ARL_edb->select_history_requests_above_serial_id (
     TALER_ARL_edb->cls,
@@ -1823,6 +1968,9 @@ run (void *cls,
                  (report_reserve_balance_insufficient_inconsistencies
                     = json_array ()));
   GNUNET_assert (NULL !=
+                 (report_purse_balance_insufficient_inconsistencies
+                    = json_array ()));
+  GNUNET_assert (NULL !=
                  (report_reserve_not_closed_inconsistencies
                     = json_array ()));
   GNUNET_assert (NULL !=
@@ -1842,6 +1990,9 @@ run (void *cls,
       GNUNET_JSON_pack_array_steal (
         "reserve_balance_insufficient_inconsistencies",
         report_reserve_balance_insufficient_inconsistencies),
+      GNUNET_JSON_pack_array_steal (
+        "purse_balance_insufficient_inconsistencies",
+        report_purse_balance_insufficient_inconsistencies),
       /* Tested in test-auditor.sh #3 */
       TALER_JSON_pack_amount ("total_loss_balance_insufficient",
                               &total_balance_insufficient_loss),
diff --git a/src/exchangedb/plugin_exchangedb_postgres.c b/src/exchangedb/plugin_exchangedb_postgres.c
index 523ccff48..5177ff55e 100644
--- a/src/exchangedb/plugin_exchangedb_postgres.c
+++ b/src/exchangedb/plugin_exchangedb_postgres.c
@@ -904,6 +904,14 @@ prepare_statements (struct PostgresClosure *pg)
       " FROM exchange_do_purse_deposit"
       " ($1,$2,$3,$4,$5,$6,$7,$8);",
       8),
+    /* Used in #postgres_update_aggregation_transient() */
+    GNUNET_PQ_make_prepare (
+      "set_purse_balance",
+      "UPDATE purse_requests"
+      " SET balance_val=$2"
+      "    ,balance_frac=$3"
+      " WHERE purse_pub=$1;",
+      3),
     /* used in #postgres_expire_purse() */
     GNUNET_PQ_make_prepare (
       "call_expire_purse",
@@ -1503,19 +1511,27 @@ prepare_statements (struct PostgresClosure *pg)
     GNUNET_PQ_make_prepare (
       "audit_get_purse_deposits_incr",
       "SELECT"
-      " amount_with_fee_val"
-      ",amount_with_fee_frac"
-      ",purse_pub"
-      ",coin_sig"
+      " pd.amount_with_fee_val"
+      ",pd.amount_with_fee_frac"
+      ",pr.amount_with_fee_val AS total_val"
+      ",pr.amount_with_fee_frac AS total_frac"
+      ",pr.balance_val"
+      ",pr.balance_frac"
+      ",pr.flags"
+      ",pd.purse_pub"
+      ",pd.coin_sig"
       ",partner_base_url"
       ",denom.denom_pub"
+      ",pm.reserve_pub"
       ",kc.coin_pub"
       ",kc.age_commitment_hash"
-      ",purse_deposit_serial_id"
-      " FROM purse_deposits"
+      ",pd.purse_deposit_serial_id"
+      " FROM purse_deposits pd"
       " LEFT JOIN partners USING (partner_serial_id)"
-      "    JOIN known_coins kc USING (coin_pub)"
-      "    JOIN denominations denom USING (denominations_serial)"
+      " LEFT JOIN purse_merges pm USING (purse_pub)"
+      " JOIN purse_requests pr USING (purse_pub)"
+      " JOIN known_coins kc USING (coin_pub)"
+      " JOIN denominations denom USING (denominations_serial)"
       " WHERE ("
       "  (purse_deposit_serial_id>=$1)"
       " )"
@@ -1554,6 +1570,8 @@ prepare_statements (struct PostgresClosure *pg)
       ",partner_base_url"
       ",pr.amount_with_fee_val"
       ",pr.amount_with_fee_frac"
+      ",pr.balance_val"
+      ",pr.balance_frac"
       ",pr.flags"
       ",pr.merge_pub"
       ",pm.reserve_pub"
@@ -10532,21 +10550,36 @@ purse_deposit_serial_helper_cb (void *cls,
     };
     struct TALER_DenominationPublicKey denom_pub;
     uint64_t rowid;
+    uint32_t flags32;
+    struct TALER_ReservePublicKeyP reserve_pub;
+    bool not_merged = false;
+    struct TALER_Amount purse_balance;
+    struct TALER_Amount purse_total;
     struct GNUNET_PQ_ResultSpec rs[] = {
       TALER_PQ_RESULT_SPEC_AMOUNT ("amount_with_fee",
                                    &deposit.amount),
+      TALER_PQ_RESULT_SPEC_AMOUNT ("balance",
+                                   &purse_balance),
+      TALER_PQ_RESULT_SPEC_AMOUNT ("total",
+                                   &purse_total),
       TALER_PQ_RESULT_SPEC_AMOUNT ("deposit_fee",
                                    &deposit.deposit_fee),
       GNUNET_PQ_result_spec_allow_null (
         GNUNET_PQ_result_spec_string ("partner_base_url",
                                       &deposit.exchange_base_url),
         NULL),
+      GNUNET_PQ_result_spec_allow_null (
+        GNUNET_PQ_result_spec_auto_from_type ("reserve_pub",
+                                              &reserve_pub),
+        &not_merged),
       TALER_PQ_result_spec_denom_pub ("denom_pub",
                                       &denom_pub),
       GNUNET_PQ_result_spec_auto_from_type ("purse_pub",
                                             &deposit.purse_pub),
       GNUNET_PQ_result_spec_auto_from_type ("coin_sig",
                                             &deposit.coin_sig),
+      GNUNET_PQ_result_spec_uint32 ("flags",
+                                    &flags32),
       GNUNET_PQ_result_spec_auto_from_type ("coin_pub",
                                             &deposit.coin_pub),
       GNUNET_PQ_result_spec_allow_null (
@@ -10574,6 +10607,10 @@ purse_deposit_serial_helper_cb (void *cls,
     ret = dsc->cb (dsc->cb_cls,
                    rowid,
                    &deposit,
+                   not_merged ? NULL : &reserve_pub,
+                   (enum TALER_WalletAccountMergeFlags) flags32,
+                   &purse_balance,
+                   &purse_total,
                    &denom_pub);
     GNUNET_PQ_cleanup_result (rs);
     if (GNUNET_OK != ret)
@@ -10827,6 +10864,7 @@ purse_merges_serial_helper_cb (void *cls,
     uint64_t rowid;
     char *partner_base_url = NULL;
     struct TALER_Amount amount;
+    struct TALER_Amount balance;
     uint32_t flags32;
     enum TALER_WalletAccountMergeFlags flags;
     struct TALER_PurseMergePublicKeyP merge_pub;
@@ -10837,6 +10875,8 @@ purse_merges_serial_helper_cb (void *cls,
     struct GNUNET_PQ_ResultSpec rs[] = {
       TALER_PQ_RESULT_SPEC_AMOUNT ("amount_with_fee",
                                    &amount),
+      TALER_PQ_RESULT_SPEC_AMOUNT ("balance",
+                                   &balance),
       GNUNET_PQ_result_spec_allow_null (
         GNUNET_PQ_result_spec_string ("partner_base_url",
                                       &partner_base_url),
@@ -10873,6 +10913,7 @@ purse_merges_serial_helper_cb (void *cls,
                    rowid,
                    partner_base_url,
                    &amount,
+                   &balance,
                    flags,
                    &merge_pub,
                    &reserve_pub,
@@ -15541,6 +15582,35 @@ postgres_do_purse_deposit (
 
 
 /**
+ * Set the current @a balance in the purse
+ * identified by @a purse_pub. Used by the auditor
+ * to update the balance as calculated by the auditor.
+ *
+ * @param cls closure
+ * @param purse_pub public key of a purse
+ * @param balance new balance to store under the purse
+ * @return transaction status
+ */
+static enum GNUNET_DB_QueryStatus
+postgres_set_purse_balance (
+  void *cls,
+  const struct TALER_PurseContractPublicKeyP *purse_pub,
+  const struct TALER_Amount *balance)
+{
+  struct PostgresClosure *pg = cls;
+  struct GNUNET_PQ_QueryParam params[] = {
+    GNUNET_PQ_query_param_auto_from_type (purse_pub),
+    TALER_PQ_query_param_amount (balance),
+    GNUNET_PQ_query_param_end
+  };
+
+  return GNUNET_PQ_eval_prepared_non_select (pg->conn,
+                                             "set_purse_balance",
+                                             params);
+}
+
+
+/**
  * Function called to obtain a coin deposit data from
  * depositing the coin into a purse.
  *
@@ -16171,6 +16241,8 @@ libtaler_plugin_exchangedb_postgres_init (void *cls)
     = &postgres_select_purse_by_merge_pub;
   plugin->do_purse_deposit
     = &postgres_do_purse_deposit;
+  plugin->set_purse_balance
+    = &postgres_set_purse_balance;
   plugin->get_purse_deposit
     = &postgres_get_purse_deposit;
   plugin->do_purse_merge
diff --git a/src/include/taler_exchangedb_plugin.h b/src/include/taler_exchangedb_plugin.h
index 5ef4e74ad..2c59d6785 100644
--- a/src/include/taler_exchangedb_plugin.h
+++ b/src/include/taler_exchangedb_plugin.h
@@ -1990,6 +1990,11 @@ typedef enum GNUNET_GenericReturnValue
  * @param cls closure
  * @param rowid unique serial ID for the deposit in our DB
  * @param deposit deposit details
+ * @param reserve_pub which reserve is the purse merged into, NULL if unknown
+ * @param flags purse flags
+ * @param auditor_balance purse balance (according to the
+ *          auditor during auditing)
+ * @param purse_total target amount the purse should reach
  * @param denom_pub denomination public key of @a coin_pub
  * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
  */
@@ -1998,6 +2003,10 @@ typedef enum GNUNET_GenericReturnValue
   void *cls,
   uint64_t rowid,
   const struct TALER_EXCHANGEDB_PurseDeposit *deposit,
+  const struct TALER_ReservePublicKeyP *reserve_pub,
+  enum TALER_WalletAccountMergeFlags flags,
+  const struct TALER_Amount *auditor_balance,
+  const struct TALER_Amount *purse_total,
   const struct TALER_DenominationPublicKey *denom_pub);
 
 
@@ -2033,6 +2042,15 @@ typedef enum GNUNET_GenericReturnValue
  *
  * @param cls closure
  * @param rowid unique serial ID for the deposit in our DB
+ * @param partner_base_url where is the reserve, NULL for this exchange
+ * @param amount total amount expected in the purse
+ * @param balance current balance in the purse (according to the auditor)
+ * @param flags purse flags
+ * @param merge_pub merge capability key
+ * @param reserve_pub reserve the merge affects
+ * @param merge_sig signature affirming the merge
+ * @param purse_pub purse key
+ * @param merge_timestamp when did the merge happen
  * @return #GNUNET_OK to continue to iterate, #GNUNET_SYSERR to stop
  */
 typedef enum GNUNET_GenericReturnValue
@@ -2041,6 +2059,7 @@ typedef enum GNUNET_GenericReturnValue
   uint64_t rowid,
   const char *partner_base_url,
   const struct TALER_Amount *amount,
+  const struct TALER_Amount *balance,
   enum TALER_WalletAccountMergeFlags flags,
   const struct TALER_PurseMergePublicKeyP *merge_pub,
   const struct TALER_ReservePublicKeyP *reserve_pub,
@@ -5291,6 +5310,23 @@ struct TALER_EXCHANGEDB_Plugin
 
 
   /**
+   * Set the current @a balance in the purse
+   * identified by @a purse_pub. Used by the auditor
+   * to update the balance as calculated by the auditor.
+   *
+   * @param cls closure
+   * @param purse_pub public key of a purse
+   * @param balance new balance to store under the purse
+   * @return transaction status
+   */
+  enum GNUNET_DB_QueryStatus
+  (*set_purse_balance)(
+    void *cls,
+    const struct TALER_PurseContractPublicKeyP *purse_pub,
+    const struct TALER_Amount *balance);
+
+
+  /**
    * Function called to obtain a coin deposit data from
    * depositing the coin into a purse.
    *
diff --git a/src/lib/exchange_api_purse_merge.c b/src/lib/exchange_api_purse_merge.c
index 6b6c37519..abe6d8cf9 100644
--- a/src/lib/exchange_api_purse_merge.c
+++ b/src/lib/exchange_api_purse_merge.c
@@ -119,50 +119,6 @@ struct TALER_EXCHANGE_AccountMergeHandle
 };
 
 
-static char *
-make_payto (const char *exchange_url,
-            const struct TALER_ReservePublicKeyP *reserve_pub)
-{
-  char pub_str[sizeof (*reserve_pub) * 2];
-  char *end;
-  bool is_http;
-  char *reserve_url;
-
-  end = GNUNET_STRINGS_data_to_string (
-    reserve_pub,
-    sizeof (*reserve_pub),
-    pub_str,
-    sizeof (pub_str));
-  *end = '\0';
-  if (0 == strncmp (exchange_url,
-                    "http://",
-                    strlen ("http://")))
-  {
-    is_http = true;
-    exchange_url = &exchange_url[strlen ("http://")];
-  }
-  else if (0 == strncmp (exchange_url,
-                         "https://",
-                         strlen ("https://")))
-  {
-    is_http = false;
-    exchange_url = &exchange_url[strlen ("https://")];
-  }
-  else
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
-  /* exchange_url includes trailing '/' */
-  GNUNET_asprintf (&reserve_url,
-                   "payto://%s/%s%s",
-                   is_http ? "taler+http" : "taler",
-                   exchange_url,
-                   pub_str);
-  return reserve_url;
-}
-
-
 /**
  * Function called when we're done processing the
  * HTTP /purse/$PID/merge request.
@@ -379,8 +335,8 @@ TALER_EXCHANGE_account_merge (
                      "/purses/%s/merge",
                      pub_str);
   }
-  reserve_url = make_payto (pch->provider_url,
-                            &pch->reserve_pub);
+  reserve_url = TALER_reserve_make_payto (pch->provider_url,
+                                          &pch->reserve_pub);
   if (NULL == reserve_url)
   {
     GNUNET_break (0);