fixing #4230 in bank-lib

1 files changed, 2599 insertions, 0 deletions

diff --git a/src/exchange-lib/test_exchange_api.c b/src/exchange-lib/test_exchange_api.c
new file mode 100644
index 000000000..80e2c6add
--- /dev/null
+++ b/src/exchange-lib/test_exchange_api.c
@@ -0,0 +1,2599 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014, 2015, 2016 GNUnet e.V.
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file exchange/test_exchange_api.c
+ * @brief testcase to test exchange's HTTP API interface
+ * @author Sree Harsha Totakura <sreeharsha@totakura.in>
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler_util.h"
+#include "taler_signatures.h"
+#include "taler_exchange_service.h"
+#include <gnunet/gnunet_util_lib.h>
+#include <microhttpd.h>
+
+/**
+ * Is the configuration file is set to include wire format 'test'?
+ */
+#define WIRE_TEST 1
+
+/**
+ * Is the configuration file is set to include wire format 'sepa'?
+ */
+#define WIRE_SEPA 1
+
+/**
+ * Main execution context for the main loop.
+ */
+static struct TALER_EXCHANGE_Context *ctx;
+
+/**
+ * Handle to access the exchange.
+ */
+static struct TALER_EXCHANGE_Handle *exchange;
+
+/**
+ * Task run on shutdown.
+ */
+static struct GNUNET_SCHEDULER_Task *shutdown_task;
+
+/**
+ * Task that runs the main event loop.
+ */
+static struct GNUNET_SCHEDULER_Task *ctx_task;
+
+/**
+ * Result of the testcases, #GNUNET_OK on success
+ */
+static int result;
+
+
+/**
+ * Opcodes for the interpreter.
+ */
+enum OpCode
+{
+  /**
+   * Termination code, stops the interpreter loop (with success).
+   */
+  OC_END = 0,
+
+  /**
+   * Add funds to a reserve by (faking) incoming wire transfer.
+   */
+  OC_ADMIN_ADD_INCOMING,
+
+  /**
+   * Check status of a reserve.
+   */
+  OC_WITHDRAW_STATUS,
+
+  /**
+   * Withdraw a coin from a reserve.
+   */
+  OC_WITHDRAW_SIGN,
+
+  /**
+   * Deposit a coin (pay with it).
+   */
+  OC_DEPOSIT,
+
+  /**
+   * Melt a (set of) coins.
+   */
+  OC_REFRESH_MELT,
+
+  /**
+   * Complete melting session by withdrawing melted coins.
+   */
+  OC_REFRESH_REVEAL,
+
+  /**
+   * Verify exchange's /refresh/link by linking original private key to
+   * results from #OC_REFRESH_REVEAL step.
+   */
+  OC_REFRESH_LINK,
+
+  /**
+   * Verify the exchange's /wire-method.
+   */
+  OC_WIRE,
+
+  /**
+   * Verify exchange's /wire/deposits method.
+   */
+  OC_WIRE_DEPOSITS,
+
+  /**
+   * Verify exchange's /deposit/wtid method.
+   */
+  OC_DEPOSIT_WTID
+
+};
+
+
+/**
+ * Structure specifying details about a coin to be melted.
+ * Used in a NULL-terminated array as part of command
+ * specification.
+ */
+struct MeltDetails
+{
+
+  /**
+   * Amount to melt (including fee).
+   */
+  const char *amount;
+
+  /**
+   * Reference to reserve_withdraw operations for coin to
+   * be used for the /refresh/melt operation.
+   */
+  const char *coin_ref;
+
+};
+
+
+/**
+ * Information about a fresh coin generated by the refresh operation.
+ */
+struct FreshCoin
+{
+
+  /**
+   * If @e amount is NULL, this specifies the denomination key to
+   * use.  Otherwise, this will be set (by the interpreter) to the
+   * denomination PK matching @e amount.
+   */
+  const struct TALER_EXCHANGE_DenomPublicKey *pk;
+
+  /**
+   * Set (by the interpreter) to the exchange's signature over the
+   * coin's public key.
+   */
+  struct TALER_DenominationSignature sig;
+
+  /**
+   * Set (by the interpreter) to the coin's private key.
+   */
+  struct TALER_CoinSpendPrivateKeyP coin_priv;
+
+};
+
+
+/**
+ * Details for a exchange operation to execute.
+ */
+struct Command
+{
+  /**
+   * Opcode of the command.
+   */
+  enum OpCode oc;
+
+  /**
+   * Label for the command, can be NULL.
+   */
+  const char *label;
+
+  /**
+   * Which response code do we expect for this command?
+   */
+  unsigned int expected_response_code;
+
+  /**
+   * Details about the command.
+   */
+  union
+  {
+
+    /**
+     * Information for a #OC_ADMIN_ADD_INCOMING command.
+     */
+    struct
+    {
+
+      /**
+       * Label to another admin_add_incoming command if we
+       * should deposit into an existing reserve, NULL if
+       * a fresh reserve should be created.
+       */
+      const char *reserve_reference;
+
+      /**
+       * String describing the amount to add to the reserve.
+       */
+      const char *amount;
+
+      /**
+       * Wire details (JSON).
+       */
+      const char *wire;
+
+      /**
+       * Set (by the interpreter) to the reserve's private key
+       * we used to fill the reserve.
+       */
+      struct TALER_ReservePrivateKeyP reserve_priv;
+
+      /**
+       * Set to the API's handle during the operation.
+       */
+      struct TALER_EXCHANGE_AdminAddIncomingHandle *aih;
+
+    } admin_add_incoming;
+
+    /**
+     * Information for a #OC_WITHDRAW_STATUS command.
+     */
+    struct
+    {
+
+      /**
+       * Label to the #OC_ADMIN_ADD_INCOMING command which
+       * created the reserve.
+       */
+      const char *reserve_reference;
+
+      /**
+       * Set to the API's handle during the operation.
+       */
+      struct TALER_EXCHANGE_ReserveStatusHandle *wsh;
+
+      /**
+       * Expected reserve balance.
+       */
+      const char *expected_balance;
+
+    } reserve_status;
+
+    /**
+     * Information for a #OC_WITHDRAW_SIGN command.
+     */
+    struct
+    {
+
+      /**
+       * Which reserve should we withdraw from?
+       */
+      const char *reserve_reference;
+
+      /**
+       * String describing the denomination value we should withdraw.
+       * A corresponding denomination key must exist in the exchange's
+       * offerings.  Can be NULL if @e pk is set instead.
+       */
+      const char *amount;
+
+      /**
+       * If @e amount is NULL, this specifies the denomination key to
+       * use.  Otherwise, this will be set (by the interpreter) to the
+       * denomination PK matching @e amount.
+       */
+      const struct TALER_EXCHANGE_DenomPublicKey *pk;
+
+      /**
+       * Set (by the interpreter) to the exchange's signature over the
+       * coin's public key.
+       */
+      struct TALER_DenominationSignature sig;
+
+      /**
+       * Set (by the interpreter) to the coin's private key.
+       */
+      struct TALER_CoinSpendPrivateKeyP coin_priv;
+
+      /**
+       * Blinding key used for the operation.
+       */
+      struct TALER_DenominationBlindingKey blinding_key;
+
+      /**
+       * Withdraw handle (while operation is running).
+       */
+      struct TALER_EXCHANGE_ReserveWithdrawHandle *wsh;
+
+    } reserve_withdraw;
+
+    /**
+     * Information for a #OC_DEPOSIT command.
+     */
+    struct
+    {
+
+      /**
+       * Amount to deposit.
+       */
+      const char *amount;
+
+      /**
+       * Reference to a reserve_withdraw operation for a coin to
+       * be used for the /deposit operation.
+       */
+      const char *coin_ref;
+
+      /**
+       * If this @e coin_ref refers to an operation that generated
+       * an array of coins, this value determines which coin to use.
+       */
+      unsigned int coin_idx;
+
+      /**
+       * JSON string describing the merchant's "wire details".
+       */
+      const char *wire_details;
+
+      /**
+       * JSON string describing the contract between the two parties.
+       */
+      const char *contract;
+
+      /**
+       * Transaction ID to use.
+       */
+      uint64_t transaction_id;
+
+      /**
+       * Relative time (to add to 'now') to compute the refund deadline.
+       * Zero for no refunds.
+       */
+      struct GNUNET_TIME_Relative refund_deadline;
+
+      /**
+       * Set (by the interpreter) to a fresh private key of the merchant,
+       * if @e refund_deadline is non-zero.
+       */
+      struct TALER_MerchantPrivateKeyP merchant_priv;
+
+      /**
+       * Deposit handle while operation is running.
+       */
+      struct TALER_EXCHANGE_DepositHandle *dh;
+
+    } deposit;
+
+    /**
+     * Information for a #OC_REFRESH_MELT command.
+     */
+    struct
+    {
+
+      /**
+       * Information about coins to be melted.
+       */
+      struct MeltDetails *melted_coins;
+
+      /**
+       * Denominations of the fresh coins to withdraw.
+       */
+      const char **fresh_amounts;
+
+      /**
+       * Array of the public keys corresponding to
+       * the @e fresh_amounts, set by the interpreter.
+       */
+      const struct TALER_EXCHANGE_DenomPublicKey **fresh_pks;
+
+      /**
+       * Melt handle while operation is running.
+       */
+      struct TALER_EXCHANGE_RefreshMeltHandle *rmh;
+
+      /**
+       * Data used in the refresh operation, set by the interpreter.
+       */
+      char *refresh_data;
+
+      /**
+       * Number of bytes in @e refresh_data, set by the interpreter.
+       */
+      size_t refresh_data_length;
+
+      /**
+       * Set by the interpreter (upon completion) to the noreveal
+       * index selected by the exchange.
+       */
+      uint16_t noreveal_index;
+
+    } refresh_melt;
+
+    /**
+     * Information for a #OC_REFRESH_REVEAL command.
+     */
+    struct
+    {
+
+      /**
+       * Melt operation this is the matching reveal for.
+       */
+      const char *melt_ref;
+
+      /**
+       * Reveal handle while operation is running.
+       */
+      struct TALER_EXCHANGE_RefreshRevealHandle *rrh;
+
+      /**
+       * Number of fresh coins withdrawn, set by the interpreter.
+       * Length of the @e fresh_coins array.
+       */
+      unsigned int num_fresh_coins;
+
+      /**
+       * Information about coins withdrawn, set by the interpreter.
+       */
+      struct FreshCoin *fresh_coins;
+
+    } refresh_reveal;
+
+    /**
+     * Information for a #OC_REFRESH_LINK command.
+     */
+    struct
+    {
+
+      /**
+       * Reveal operation this is the matching link for.
+       */
+      const char *reveal_ref;
+
+      /**
+       * Link handle while operation is running.
+       */
+      struct TALER_EXCHANGE_RefreshLinkHandle *rlh;
+
+      /**
+       * Which of the melted coins should be used for the linkage?
+       */
+      unsigned int coin_idx;
+
+    } refresh_link;
+
+    /**
+     * Information for the /wire command.
+     */
+    struct {
+
+      /**
+       * Handle to the wire request.
+       */
+      struct TALER_EXCHANGE_WireHandle *wh;
+
+      /**
+       * Format we expect to see, others will be *ignored*.
+       */
+      const char *format;
+
+    } wire;
+
+    /**
+     * Information for the /wire/deposits's command.
+     */
+    struct {
+
+      /**
+       * Handle to the wire deposits request.
+       */
+      struct TALER_EXCHANGE_WireDepositsHandle *wdh;
+
+      /**
+       * Reference to a /deposit/wtid command. If set, we use the
+       * WTID from that command.
+       */
+      const char *wtid_ref;
+
+      /**
+       * WTID to use (used if @e wtid_ref is NULL).
+       */
+      struct TALER_WireTransferIdentifierRawP wtid;
+
+      /* TODO: may want to add list of deposits we expected
+         to see aggregated here in the future. */
+
+    } wire_deposits;
+
+    /**
+     * Information for the /deposit/wtid command.
+     */
+    struct {
+
+      /**
+       * Handle to the deposit wtid request.
+       */
+      struct TALER_EXCHANGE_DepositWtidHandle *dwh;
+
+      /**
+       * Which /deposit operation should we obtain WTID data for?
+       */
+      const char *deposit_ref;
+
+      /**
+       * What is the expected total amount? Only used if
+       * @e expected_response_code was #MHD_HTTP_OK.
+       */
+      struct TALER_Amount total_amount_expected;
+
+      /**
+       * Wire transfer identifier, set if #MHD_HTTP_OK was the response code.
+       */
+      struct TALER_WireTransferIdentifierRawP wtid;
+
+    } deposit_wtid;
+
+  } details;
+
+};
+
+
+/**
+ * State of the interpreter loop.
+ */
+struct InterpreterState
+{
+  /**
+   * Keys from the exchange.
+   */
+  const struct TALER_EXCHANGE_Keys *keys;
+
+  /**
+   * Commands the interpreter will run.
+   */
+  struct Command *commands;
+
+  /**
+   * Interpreter task (if one is scheduled).
+   */
+  struct GNUNET_SCHEDULER_Task *task;
+
+  /**
+   * Instruction pointer.  Tells #interpreter_run() which
+   * instruction to run next.
+   */
+  unsigned int ip;
+
+};
+
+
+/**
+ * Task that runs the context's event loop with the GNUnet scheduler.
+ *
+ * @param cls unused
+ * @param tc scheduler context (unused)
+ */
+static void
+context_task (void *cls,
+              const struct GNUNET_SCHEDULER_TaskContext *tc);
+
+
+/**
+ * Run the context task, the working set has changed.
+ */
+static void
+trigger_context_task ()
+{
+  GNUNET_SCHEDULER_cancel (ctx_task);
+  ctx_task = GNUNET_SCHEDULER_add_now (&context_task,
+                                       NULL);
+}
+
+
+/**
+ * The testcase failed, return with an error code.
+ *
+ * @param is interpreter state to clean up
+ */
+static void
+fail (struct InterpreterState *is)
+{
+  result = GNUNET_SYSERR;
+  GNUNET_SCHEDULER_shutdown ();
+}
+
+
+/**
+ * Find a command by label.
+ *
+ * @param is interpreter state to search
+ * @param label label to look for
+ * @return NULL if command was not found
+ */
+static const struct Command *
+find_command (const struct InterpreterState *is,
+              const char *label)
+{
+  unsigned int i;
+  const struct Command *cmd;
+
+  if (NULL == label)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                "Attempt to lookup command for empty label\n");
+    return NULL;
+  }
+  for (i=0;OC_END != (cmd = &is->commands[i])->oc;i++)
+    if ( (NULL != cmd->label) &&
+         (0 == strcmp (cmd->label,
+                       label)) )
+      return cmd;
+  GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+              "Command not found: %s\n",
+              label);
+  return NULL;
+}
+
+
+/**
+ * Run the main interpreter loop that performs exchange operations.
+ *
+ * @param cls contains the `struct InterpreterState`
+ * @param tc scheduler context
+ */
+static void
+interpreter_run (void *cls,
+                 const struct GNUNET_SCHEDULER_TaskContext *tc);
+
+
+/**
+ * Function called upon completion of our /admin/add/incoming request.
+ *
+ * @param cls closure with the interpreter state
+ * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
+ *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param full_response full response from the exchange (for logging, in case of errors)
+ */
+static void
+add_incoming_cb (void *cls,
+                 unsigned int http_status,
+                 json_t *full_response)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+
+  cmd->details.admin_add_incoming.aih = NULL;
+  if (MHD_HTTP_OK != http_status)
+  {
+    GNUNET_break (0);
+    fail (is);
+    return;
+  }
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Check if the given historic event @a h corresponds to the given
+ * command @a cmd.
+ *
+ * @param h event in history
+ * @param cmd an #OC_ADMIN_ADD_INCOMING command
+ * @return #GNUNET_OK if they match, #GNUNET_SYSERR if not
+ */
+static int
+compare_admin_add_incoming_history (const struct TALER_EXCHANGE_ReserveHistory *h,
+                                    const struct Command *cmd)
+{
+  struct TALER_Amount amount;
+
+  if (TALER_EXCHANGE_RTT_DEPOSIT != h->type)
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  GNUNET_assert (GNUNET_OK ==
+                 TALER_string_to_amount (cmd->details.admin_add_incoming.amount,
+                                         &amount));
+  if (0 != TALER_amount_cmp (&amount,
+                             &h->amount))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Check if the given historic event @a h corresponds to the given
+ * command @a cmd.
+ *
+ * @param h event in history
+ * @param cmd an #OC_WITHDRAW_SIGN command
+ * @return #GNUNET_OK if they match, #GNUNET_SYSERR if not
+ */
+static int
+compare_reserve_withdraw_history (const struct TALER_EXCHANGE_ReserveHistory *h,
+                                  const struct Command *cmd)
+{
+  struct TALER_Amount amount;
+  struct TALER_Amount amount_with_fee;
+
+  if (TALER_EXCHANGE_RTT_WITHDRAWAL != h->type)
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  GNUNET_assert (GNUNET_OK ==
+                 TALER_string_to_amount (cmd->details.reserve_withdraw.amount,
+                                         &amount));
+  GNUNET_assert (GNUNET_OK ==
+                 TALER_amount_add (&amount_with_fee,
+                                   &amount,
+                                   &cmd->details.reserve_withdraw.pk->fee_withdraw));
+  if (0 != TALER_amount_cmp (&amount_with_fee,
+                             &h->amount))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Function called with the result of a /reserve/status request.
+ *
+ * @param cls closure with the interpreter state
+ * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
+ *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param[in] json original response in JSON format (useful only for diagnostics)
+ * @param balance current balance in the reserve, NULL on error
+ * @param history_length number of entries in the transaction history, 0 on error
+ * @param history detailed transaction history, NULL on error
+ */
+static void
+reserve_status_cb (void *cls,
+                   unsigned int http_status,
+                   json_t *json,
+                   const struct TALER_Amount *balance,
+                   unsigned int history_length,
+                   const struct TALER_EXCHANGE_ReserveHistory *history)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+  struct Command *rel;
+  unsigned int i;
+  unsigned int j;
+  struct TALER_Amount amount;
+
+  cmd->details.reserve_status.wsh = NULL;
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s\n",
+                http_status,
+                cmd->label);
+    GNUNET_break (0);
+    json_dumpf (json, stderr, 0);
+    fail (is);
+    return;
+  }
+  switch (http_status)
+  {
+  case MHD_HTTP_OK:
+    /* FIXME: note that history events may come in a different
+       order than the commands. However, for now this works... */
+    j = 0;
+    for (i=0;i<is->ip;i++)
+    {
+      switch ((rel = &is->commands[i])->oc)
+      {
+      case OC_ADMIN_ADD_INCOMING:
+        if ( ( (NULL != rel->label) &&
+               (0 == strcmp (cmd->details.reserve_status.reserve_reference,
+                             rel->label) ) ) ||
+             ( (NULL != rel->details.admin_add_incoming.reserve_reference) &&
+               (0 == strcmp (cmd->details.reserve_status.reserve_reference,
+                             rel->details.admin_add_incoming.reserve_reference) ) ) )
+        {
+          if (GNUNET_OK !=
+              compare_admin_add_incoming_history (&history[j],
+                                                  rel))
+          {
+            GNUNET_break (0);
+            fail (is);
+            return;
+          }
+          j++;
+        }
+        break;
+      case OC_WITHDRAW_SIGN:
+        if (0 == strcmp (cmd->details.reserve_status.reserve_reference,
+                         rel->details.reserve_withdraw.reserve_reference))
+        {
+          if (GNUNET_OK !=
+              compare_reserve_withdraw_history (&history[j],
+                                             rel))
+          {
+            GNUNET_break (0);
+            fail (is);
+            return;
+          }
+          j++;
+        }
+        break;
+      default:
+        /* unreleated, just skip */
+        break;
+      }
+    }
+    if (j != history_length)
+    {
+      GNUNET_break (0);
+      fail (is);
+      return;
+    }
+    if (NULL != cmd->details.reserve_status.expected_balance)
+    {
+      GNUNET_assert (GNUNET_OK ==
+                     TALER_string_to_amount (cmd->details.reserve_status.expected_balance,
+                                             &amount));
+      if (0 != TALER_amount_cmp (&amount,
+                                 balance))
+      {
+        GNUNET_break (0);
+        fail (is);
+        return;
+      }
+    }
+    break;
+  default:
+    /* Unsupported status code (by test harness) */
+    GNUNET_break (0);
+    break;
+  }
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Function called upon completion of our /reserve/withdraw request.
+ *
+ * @param cls closure with the interpreter state
+ * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
+ *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param sig signature over the coin, NULL on error
+ * @param full_response full response from the exchange (for logging, in case of errors)
+ */
+static void
+reserve_withdraw_cb (void *cls,
+                     unsigned int http_status,
+                     const struct TALER_DenominationSignature *sig,
+                     json_t *full_response)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+
+  cmd->details.reserve_withdraw.wsh = NULL;
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s\n",
+                http_status,
+                cmd->label);
+    json_dumpf (full_response, stderr, 0);
+    GNUNET_break (0);
+    fail (is);
+    return;
+  }
+  switch (http_status)
+  {
+  case MHD_HTTP_OK:
+    if (NULL == sig)
+    {
+      GNUNET_break (0);
+      fail (is);
+      return;
+    }
+    cmd->details.reserve_withdraw.sig.rsa_signature
+      = GNUNET_CRYPTO_rsa_signature_dup (sig->rsa_signature);
+    break;
+  case MHD_HTTP_PAYMENT_REQUIRED:
+    /* nothing to check */
+    break;
+  default:
+    /* Unsupported status code (by test harness) */
+    GNUNET_break (0);
+    break;
+  }
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Function called with the result of a /deposit operation.
+ *
+ * @param cls closure with the interpreter state
+ * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful deposit;
+ *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param obj the received JSON reply, should be kept as proof (and, in case of errors,
+ *            be forwarded to the customer)
+ */
+static void
+deposit_cb (void *cls,
+            unsigned int http_status,
+            json_t *obj)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+
+  cmd->details.deposit.dh = NULL;
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s\n",
+                http_status,
+                cmd->label);
+    json_dumpf (obj, stderr, 0);
+    fail (is);
+    return;
+  }
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Function called with the result of the /refresh/melt operation.
+ *
+ * @param cls closure with the interpreter state
+ * @param http_status HTTP response code, never #MHD_HTTP_OK (200) as for successful intermediate response this callback is skipped.
+ *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param noreveal_index choice by the exchange in the cut-and-choose protocol,
+ *                    UINT16_MAX on error
+ * @param full_response full response from the exchange (for logging, in case of errors)
+ */
+static void
+melt_cb (void *cls,
+         unsigned int http_status,
+         uint16_t noreveal_index,
+         json_t *full_response)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+
+  cmd->details.refresh_melt.rmh = NULL;
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s\n",
+                http_status,
+                cmd->label);
+    json_dumpf (full_response, stderr, 0);
+    fail (is);
+    return;
+  }
+  cmd->details.refresh_melt.noreveal_index = noreveal_index;
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Function called with the result of the /refresh/reveal operation.
+ *
+ * @param cls closure with the interpreter state
+ * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
+ *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param num_coins number of fresh coins created, length of the @a sigs and @a coin_privs arrays, 0 if the operation failed
+ * @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
+ * @param full_response full response from the exchange (for logging, in case of errors)
+ */
+static void
+reveal_cb (void *cls,
+           unsigned int http_status,
+           unsigned int num_coins,
+           const struct TALER_CoinSpendPrivateKeyP *coin_privs,
+           const struct TALER_DenominationSignature *sigs,
+           json_t *full_response)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+  const struct Command *ref;
+  unsigned int i;
+
+  cmd->details.refresh_reveal.rrh = NULL;
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s\n",
+                http_status,
+                cmd->label);
+    json_dumpf (full_response, stderr, 0);
+    fail (is);
+    return;
+  }
+  ref = find_command (is,
+                      cmd->details.refresh_reveal.melt_ref);
+  cmd->details.refresh_reveal.num_fresh_coins = num_coins;
+  switch (http_status)
+  {
+  case MHD_HTTP_OK:
+    cmd->details.refresh_reveal.fresh_coins
+      = GNUNET_new_array (num_coins,
+                          struct FreshCoin);
+    for (i=0;i<num_coins;i++)
+    {
+      struct FreshCoin *fc = &cmd->details.refresh_reveal.fresh_coins[i];
+
+      fc->pk = ref->details.refresh_melt.fresh_pks[i];
+      fc->coin_priv = coin_privs[i];
+      fc->sig.rsa_signature
+        = GNUNET_CRYPTO_rsa_signature_dup (sigs[i].rsa_signature);
+    }
+    break;
+  default:
+    break;
+  }
+
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Function called with the result of a /refresh/link operation.
+ *
+ * @param cls closure with the interpreter state
+ * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful status request
+ *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param num_coins number of fresh coins created, length of the @a sigs and @a coin_privs arrays, 0 if the operation failed
+ * @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
+ * @param pubs array of public keys for the @a sigs, NULL on error
+ * @param full_response full response from the exchange (for logging, in case of errors)
+ */
+static void
+link_cb (void *cls,
+         unsigned int http_status,
+         unsigned int num_coins,
+         const struct TALER_CoinSpendPrivateKeyP *coin_privs,
+         const struct TALER_DenominationSignature *sigs,
+         const struct TALER_DenominationPublicKey *pubs,
+         json_t *full_response)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+  const struct Command *ref;
+  unsigned int i;
+  unsigned int j;
+  unsigned int found;
+
+  cmd->details.refresh_link.rlh = NULL;
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s\n",
+                http_status,
+                cmd->label);
+    json_dumpf (full_response, stderr, 0);
+    fail (is);
+    return;
+  }
+  ref = find_command (is,
+                      cmd->details.refresh_link.reveal_ref);
+  switch (http_status)
+  {
+  case MHD_HTTP_OK:
+    /* check that number of coins returned matches */
+    if (num_coins != ref->details.refresh_reveal.num_fresh_coins)
+    {
+      GNUNET_break (0);
+      fail (is);
+      return;
+    }
+    /* check that the coins match */
+    for (i=0;i<num_coins;i++)
+      for (j=i+1;j<num_coins;j++)
+	if (0 == memcmp (&coin_privs[i],
+			 &coin_privs[j],
+			 sizeof (struct TALER_CoinSpendPrivateKeyP)))
+	  GNUNET_break (0);
+    /* Note: coins might be legitimately permutated in here... */
+    found = 0;
+    for (i=0;i<num_coins;i++)
+      for (j=0;j<num_coins;j++)
+      {
+	const struct FreshCoin *fc;
+
+	fc = &ref->details.refresh_reveal.fresh_coins[j];
+	if ( (0 == memcmp (&coin_privs[i],
+			   &fc->coin_priv,
+			   sizeof (struct TALER_CoinSpendPrivateKeyP))) &&
+	     (0 == GNUNET_CRYPTO_rsa_signature_cmp (fc->sig.rsa_signature,
+						    sigs[i].rsa_signature)) &&
+	     (0 == GNUNET_CRYPTO_rsa_public_key_cmp (fc->pk->key.rsa_public_key,
+						     pubs[i].rsa_public_key)) )
+	{
+	  found++;
+	  break;
+	}
+      }
+    if (found != num_coins)
+    {
+      fprintf (stderr,
+	       "Only %u/%u coins match expectations\n",
+	       found,
+	       num_coins);
+      GNUNET_break (0);
+      fail (is);
+      return;
+    }
+    break;
+  default:
+    break;
+  }
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Find denomination key matching the given amount.
+ *
+ * @param keys array of keys to search
+ * @param amount coin value to look for
+ * @return NULL if no matching key was found
+ */
+static const struct TALER_EXCHANGE_DenomPublicKey *
+find_pk (const struct TALER_EXCHANGE_Keys *keys,
+         const struct TALER_Amount *amount)
+{
+  unsigned int i;
+  struct GNUNET_TIME_Absolute now;
+  struct TALER_EXCHANGE_DenomPublicKey *pk;
+  char *str;
+
+  now = GNUNET_TIME_absolute_get ();
+  for (i=0;i<keys->num_denom_keys;i++)
+  {
+    pk = &keys->denom_keys[i];
+    if ( (0 == TALER_amount_cmp (amount,
+                                 &pk->value)) &&
+         (now.abs_value_us >= pk->valid_from.abs_value_us) &&
+         (now.abs_value_us < pk->withdraw_valid_until.abs_value_us) )
+      return pk;
+  }
+  /* do 2nd pass to check if expiration times are to blame for failure */
+  str = TALER_amount_to_string (amount);
+  for (i=0;i<keys->num_denom_keys;i++)
+  {
+    pk = &keys->denom_keys[i];
+    if ( (0 == TALER_amount_cmp (amount,
+                                 &pk->value)) &&
+         ( (now.abs_value_us < pk->valid_from.abs_value_us) ||
+           (now.abs_value_us > pk->withdraw_valid_until.abs_value_us) ) )
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                  "Have denomination key for `%s', but with wrong expiration range %llu vs [%llu,%llu)\n",
+                  str,
+                  now.abs_value_us,
+                  pk->valid_from.abs_value_us,
+                  pk->withdraw_valid_until.abs_value_us);
+      GNUNET_free (str);
+      return NULL;
+    }
+  }
+  GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+              "No denomination key for amount %s found\n",
+              str);
+  GNUNET_free (str);
+  return NULL;
+}
+
+
+/**
+ * Callbacks called with the result(s) of a
+ * wire format inquiry request to the exchange.
+ *
+ * The callback is invoked multiple times, once for each supported @a
+ * method.  Finally, it is invoked one more time with cls/0/NULL/NULL
+ * to indicate the end of the iteration.  If any request fails to
+ * generate a valid response from the exchange, @a http_status will also
+ * be zero and the iteration will also end.  Thus, the iteration
+ * always ends with a final call with an @a http_status of 0. If the
+ * @a http_status is already 0 on the first call, then the response to
+ * the /wire request was invalid.  Later, clients can tell the
+ * difference between @a http_status of 0 indicating a failed
+ * /wire/method request and a regular end of the iteration by @a
+ * method being non-NULL.  If the exchange simply correctly asserts that
+ * it does not support any methods, @a method will be NULL but the @a
+ * http_status will be #MHD_HTTP_OK for the first call (followed by a
+ * cls/0/NULL/NULL call to signal the end of the iteration).
+ *
+ * @param cls closure with the interpreter state
+ * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful request;
+ *                    0 if the exchange's reply is bogus (fails to follow the protocol)
+ * @param method wire format method supported, i.e. "test" or "sepa", or NULL
+ *            if already the /wire request failed.
+ * @param obj the received JSON reply, if successful this should be the wire
+ *            format details as provided by /wire/METHOD/, or NULL if the
+ *            reply was not in JSON format (in this case, the client might
+ *            want to do an HTTP request to /wire/METHOD/ with a browser to
+ *            provide more information to the user about the @a method).
+ */
+static void
+wire_cb (void *cls,
+         unsigned int http_status,
+         const char *method,
+         json_t *obj)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+
+  if (0 == http_status)
+  {
+    /* 0 always signals the end of the iteration */
+    cmd->details.wire.wh = NULL;
+  }
+  else if ( (NULL != method) &&
+            (0 != strcasecmp (method,
+                              cmd->details.wire.format)) )
+  {
+    /* not the method we care about, skip */
+    return;
+  }
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s/%s\n",
+                http_status,
+                cmd->label,
+                method);
+    json_dumpf (obj, stderr, 0);
+    fail (is);
+    return;
+  }
+  if (0 == http_status)
+  {
+    /* end of iteration, move to next command */
+    is->ip++;
+    is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                         is);
+    return;
+  }
+  /* For now, we only support to be called only once
+     with a "positive" result; so we switch to an
+     expected value of 0 for the 2nd iteration */
+  cmd->expected_response_code = 0;
+}
+
+
+/**
+ * Function called with detailed wire transfer data, including all
+ * of the coin transactions that were combined into the wire transfer.
+ *
+ * @param cls closure
+ * @param http_status HTTP status code we got, 0 on exchange protocol violation
+ * @param json original json reply (may include signatures, those have then been
+ *        validated already)
+ * @param wtid extracted wire transfer identifier, or NULL if the exchange could
+ *             not provide any (set only if @a http_status is #MHD_HTTP_OK)
+ * @param total_amount total amount of the wire transfer, or NULL if the exchange could
+ *             not provide any @a wtid (set only if @a http_status is #MHD_HTTP_OK)
+ * @param details_length length of the @a details array
+ * @param details array with details about the combined transactions
+ */
+static void
+wire_deposits_cb (void *cls,
+                  unsigned int http_status,
+                  json_t *json,
+                  const struct GNUNET_HashCode *h_wire,
+                  const struct TALER_Amount *total_amount,
+                  unsigned int details_length,
+                  const struct TALER_WireDepositDetails *details)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+  const struct Command *ref;
+
+  cmd->details.wire_deposits.wdh = NULL;
+  ref = find_command (is,
+                      cmd->details.wire_deposits.wtid_ref);
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s\n",
+                http_status,
+                cmd->label);
+    json_dumpf (json, stderr, 0);
+    fail (is);
+    return;
+  }
+  switch (http_status)
+  {
+  case MHD_HTTP_OK:
+    if (0 != TALER_amount_cmp (total_amount,
+                               &ref->details.deposit_wtid.total_amount_expected))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Total amount missmatch to command %s\n",
+                  http_status,
+                  cmd->label);
+      json_dumpf (json, stderr, 0);
+      fail (is);
+      return;
+    }
+    if (NULL != ref->details.deposit_wtid.deposit_ref)
+    {
+      const struct Command *dep;
+      struct GNUNET_HashCode hw;
+
+      dep = find_command (is,
+                          ref->details.deposit_wtid.deposit_ref);
+      GNUNET_CRYPTO_hash (dep->details.deposit.wire_details,
+                          strlen (dep->details.deposit.wire_details),
+                          &hw);
+      if (0 != memcmp (&hw,
+                       h_wire,
+                       sizeof (struct GNUNET_HashCode)))
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                    "Wire hash missmatch to command %s\n",
+                    cmd->label);
+        json_dumpf (json, stderr, 0);
+        fail (is);
+        return;
+      }
+    }
+    break;
+  default:
+    break;
+  }
+
+  /* move to next command */
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Function called with detailed wire transfer data.
+ *
+ * @param cls closure
+ * @param http_status HTTP status code we got, 0 on exchange protocol violation
+ * @param json original json reply (may include signatures, those have then been
+ *        validated already)
+ * @param wtid wire transfer identifier used by the exchange, NULL if exchange did not
+ *                  yet execute the transaction
+ * @param execution_time actual or planned execution time for the wire transfer
+ * @param coin_contribution contribution to the @a total_amount of the deposited coin (may be NULL)
+ * @param total_amount total amount of the wire transfer, or NULL if the exchange could
+ *             not provide any @a wtid (set only if @a http_status is #MHD_HTTP_OK)
+ */
+static void
+deposit_wtid_cb (void *cls,
+                 unsigned int http_status,
+                 json_t *json,
+                 const struct TALER_WireTransferIdentifierRawP *wtid,
+                 struct GNUNET_TIME_Absolute execution_time,
+                 const struct TALER_Amount *coin_contribution)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+
+  cmd->details.deposit_wtid.dwh = NULL;
+  if (cmd->expected_response_code != http_status)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u to command %s\n",
+                http_status,
+                cmd->label);
+    json_dumpf (json, stderr, 0);
+    fail (is);
+    return;
+  }
+  switch (http_status)
+  {
+  case MHD_HTTP_OK:
+    cmd->details.deposit_wtid.wtid = *wtid;
+    break;
+  default:
+    break;
+  }
+
+  /* move to next command */
+  is->ip++;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Run the main interpreter loop that performs exchange operations.
+ *
+ * @param cls contains the `struct InterpreterState`
+ * @param tc scheduler context
+ */
+static void
+interpreter_run (void *cls,
+                 const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd = &is->commands[is->ip];
+  const struct Command *ref;
+  struct TALER_ReservePublicKeyP reserve_pub;
+  struct TALER_CoinSpendPublicKeyP coin_pub;
+  struct TALER_Amount amount;
+  struct GNUNET_TIME_Absolute execution_date;
+  json_t *wire;
+
+  is->task = NULL;
+  if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN))
+  {
+    fprintf (stderr,
+             "Test aborted by shutdown request\n");
+    fail (is);
+    return;
+  }
+  switch (cmd->oc)
+  {
+  case OC_END:
+    result = GNUNET_OK;
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  case OC_ADMIN_ADD_INCOMING:
+    if (NULL !=
+        cmd->details.admin_add_incoming.reserve_reference)
+    {
+      ref = find_command (is,
+                          cmd->details.admin_add_incoming.reserve_reference);
+      GNUNET_assert (NULL != ref);
+      GNUNET_assert (OC_ADMIN_ADD_INCOMING == ref->oc);
+      cmd->details.admin_add_incoming.reserve_priv
+        = ref->details.admin_add_incoming.reserve_priv;
+    }
+    else
+    {
+      struct GNUNET_CRYPTO_EddsaPrivateKey *priv;
+
+      priv = GNUNET_CRYPTO_eddsa_key_create ();
+      cmd->details.admin_add_incoming.reserve_priv.eddsa_priv = *priv;
+      GNUNET_free (priv);
+    }
+    GNUNET_CRYPTO_eddsa_key_get_public (&cmd->details.admin_add_incoming.reserve_priv.eddsa_priv,
+                                        &reserve_pub.eddsa_pub);
+    if (GNUNET_OK !=
+        TALER_string_to_amount (cmd->details.admin_add_incoming.amount,
+                                &amount))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Failed to parse amount `%s' at %u\n",
+                  cmd->details.admin_add_incoming.amount,
+                  is->ip);
+      fail (is);
+      return;
+    }
+    wire = json_loads (cmd->details.admin_add_incoming.wire,
+                       JSON_REJECT_DUPLICATES,
+                       NULL);
+    if (NULL == wire)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Failed to parse wire details `%s' at %u\n",
+                  cmd->details.admin_add_incoming.wire,
+                  is->ip);
+      fail (is);
+      return;
+    }
+    execution_date = GNUNET_TIME_absolute_get ();
+    TALER_round_abs_time (&execution_date);
+    cmd->details.admin_add_incoming.aih
+      = TALER_EXCHANGE_admin_add_incoming (exchange,
+                                       &reserve_pub,
+                                       &amount,
+                                       execution_date,
+                                       wire,
+                                       &add_incoming_cb,
+                                       is);
+    if (NULL == cmd->details.admin_add_incoming.aih)
+    {
+      GNUNET_break (0);
+      fail (is);
+      return;
+    }
+    trigger_context_task ();
+    return;
+  case OC_WITHDRAW_STATUS:
+    GNUNET_assert (NULL !=
+                   cmd->details.reserve_status.reserve_reference);
+    ref = find_command (is,
+                        cmd->details.reserve_status.reserve_reference);
+    GNUNET_assert (NULL != ref);
+    GNUNET_assert (OC_ADMIN_ADD_INCOMING == ref->oc);
+    GNUNET_CRYPTO_eddsa_key_get_public (&ref->details.admin_add_incoming.reserve_priv.eddsa_priv,
+                                        &reserve_pub.eddsa_pub);
+    cmd->details.reserve_status.wsh
+      = TALER_EXCHANGE_reserve_status (exchange,
+                                   &reserve_pub,
+                                   &reserve_status_cb,
+                                   is);
+    trigger_context_task ();
+    return;
+  case OC_WITHDRAW_SIGN:
+    GNUNET_assert (NULL !=
+                   cmd->details.reserve_withdraw.reserve_reference);
+    ref = find_command (is,
+                        cmd->details.reserve_withdraw.reserve_reference);
+    GNUNET_assert (NULL != ref);
+    GNUNET_assert (OC_ADMIN_ADD_INCOMING == ref->oc);
+    if (NULL != cmd->details.reserve_withdraw.amount)
+    {
+      if (GNUNET_OK !=
+          TALER_string_to_amount (cmd->details.reserve_withdraw.amount,
+                                  &amount))
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                    "Failed to parse amount `%s' at %u\n",
+                    cmd->details.reserve_withdraw.amount,
+                    is->ip);
+        fail (is);
+        return;
+      }
+      cmd->details.reserve_withdraw.pk = find_pk (is->keys,
+                                                  &amount);
+    }
+    if (NULL == cmd->details.reserve_withdraw.pk)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Failed to determine denomination key at %u\n",
+                  is->ip);
+      fail (is);
+      return;
+    }
+
+    /* create coin's private key */
+    {
+      struct GNUNET_CRYPTO_EddsaPrivateKey *priv;
+
+      priv = GNUNET_CRYPTO_eddsa_key_create ();
+      cmd->details.reserve_withdraw.coin_priv.eddsa_priv = *priv;
+      GNUNET_free (priv);
+    }
+    GNUNET_CRYPTO_eddsa_key_get_public (&cmd->details.reserve_withdraw.coin_priv.eddsa_priv,
+                                        &coin_pub.eddsa_pub);
+    cmd->details.reserve_withdraw.blinding_key.rsa_blinding_key
+      = GNUNET_CRYPTO_rsa_blinding_key_create (GNUNET_CRYPTO_rsa_public_key_len (cmd->details.reserve_withdraw.pk->key.rsa_public_key));
+    cmd->details.reserve_withdraw.wsh
+      = TALER_EXCHANGE_reserve_withdraw (exchange,
+                                     cmd->details.reserve_withdraw.pk,
+                                     &ref->details.admin_add_incoming.reserve_priv,
+                                     &cmd->details.reserve_withdraw.coin_priv,
+                                     &cmd->details.reserve_withdraw.blinding_key,
+                                     &reserve_withdraw_cb,
+                                     is);
+    if (NULL == cmd->details.reserve_withdraw.wsh)
+    {
+      GNUNET_break (0);
+      fail (is);
+      return;
+    }
+    trigger_context_task ();
+    return;
+  case OC_DEPOSIT:
+    {
+      struct GNUNET_HashCode h_contract;
+      const struct TALER_CoinSpendPrivateKeyP *coin_priv;
+      const struct TALER_EXCHANGE_DenomPublicKey *coin_pk;
+      const struct TALER_DenominationSignature *coin_pk_sig;
+      struct TALER_CoinSpendPublicKeyP coin_pub;
+      struct TALER_CoinSpendSignatureP coin_sig;
+      struct GNUNET_TIME_Absolute refund_deadline;
+      struct GNUNET_TIME_Absolute wire_deadline;
+      struct GNUNET_TIME_Absolute timestamp;
+      struct GNUNET_CRYPTO_EddsaPrivateKey *priv;
+      struct TALER_MerchantPublicKeyP merchant_pub;
+      json_t *contract;
+      json_t *wire;
+
+      GNUNET_assert (NULL !=
+                     cmd->details.deposit.coin_ref);
+      ref = find_command (is,
+                          cmd->details.deposit.coin_ref);
+      GNUNET_assert (NULL != ref);
+      switch (ref->oc)
+      {
+      case OC_WITHDRAW_SIGN:
+        coin_priv = &ref->details.reserve_withdraw.coin_priv;
+        coin_pk = ref->details.reserve_withdraw.pk;
+        coin_pk_sig = &ref->details.reserve_withdraw.sig;
+        break;
+      case OC_REFRESH_REVEAL:
+        {
+          const struct FreshCoin *fc;
+          unsigned int idx;
+
+          idx = cmd->details.deposit.coin_idx;
+          GNUNET_assert (idx < ref->details.refresh_reveal.num_fresh_coins);
+          fc = &ref->details.refresh_reveal.fresh_coins[idx];
+
+          coin_priv = &fc->coin_priv;
+          coin_pk = fc->pk;
+          coin_pk_sig = &fc->sig;
+        }
+        break;
+      default:
+        GNUNET_assert (0);
+      }
+      if (GNUNET_OK !=
+          TALER_string_to_amount (cmd->details.deposit.amount,
+                                  &amount))
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                    "Failed to parse amount `%s' at %u\n",
+                    cmd->details.deposit.amount,
+                    is->ip);
+        fail (is);
+        return;
+      }
+      contract = json_loads (cmd->details.deposit.contract,
+                             JSON_REJECT_DUPLICATES,
+                             NULL);
+      if (NULL == contract)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                    "Failed to parse contract details `%s' at %u/%s\n",
+                    cmd->details.deposit.contract,
+                    is->ip,
+                    cmd->label);
+        fail (is);
+        return;
+      }
+      TALER_hash_json (contract,
+                       &h_contract);
+      wire = json_loads (cmd->details.deposit.wire_details,
+                         JSON_REJECT_DUPLICATES,
+                         NULL);
+      if (NULL == wire)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                    "Failed to parse wire details `%s' at %u/%s\n",
+                    cmd->details.deposit.wire_details,
+                    is->ip,
+                    cmd->label);
+        fail (is);
+        return;
+      }
+      GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv->eddsa_priv,
+                                          &coin_pub.eddsa_pub);
+
+      priv = GNUNET_CRYPTO_eddsa_key_create ();
+      cmd->details.deposit.merchant_priv.eddsa_priv = *priv;
+      GNUNET_free (priv);
+      if (0 != cmd->details.deposit.refund_deadline.rel_value_us)
+      {
+        refund_deadline = GNUNET_TIME_relative_to_absolute (cmd->details.deposit.refund_deadline);
+      }
+      else
+      {
+        refund_deadline = GNUNET_TIME_UNIT_ZERO_ABS;
+      }
+      GNUNET_CRYPTO_eddsa_key_get_public (&cmd->details.deposit.merchant_priv.eddsa_priv,
+                                          &merchant_pub.eddsa_pub);
+
+      wire_deadline = GNUNET_TIME_relative_to_absolute (GNUNET_TIME_UNIT_DAYS);
+      timestamp = GNUNET_TIME_absolute_get ();
+      TALER_round_abs_time (&timestamp);
+      {
+        struct TALER_DepositRequestPS dr;
+
+        memset (&dr, 0, sizeof (dr));
+        dr.purpose.size = htonl (sizeof (struct TALER_DepositRequestPS));
+        dr.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_DEPOSIT);
+        dr.h_contract = h_contract;
+        TALER_hash_json (wire,
+                         &dr.h_wire);
+        dr.timestamp = GNUNET_TIME_absolute_hton (timestamp);
+        dr.refund_deadline = GNUNET_TIME_absolute_hton (refund_deadline);
+        dr.transaction_id = GNUNET_htonll (cmd->details.deposit.transaction_id);
+        TALER_amount_hton (&dr.amount_with_fee,
+                           &amount);
+        TALER_amount_hton (&dr.deposit_fee,
+                           &coin_pk->fee_deposit);
+        dr.merchant = merchant_pub;
+        dr.coin_pub = coin_pub;
+        GNUNET_assert (GNUNET_OK ==
+                       GNUNET_CRYPTO_eddsa_sign (&coin_priv->eddsa_priv,
+                                                 &dr.purpose,
+                                                 &coin_sig.eddsa_signature));
+      }
+      cmd->details.deposit.dh
+        = TALER_EXCHANGE_deposit (exchange,
+                              &amount,
+                              wire_deadline,
+                              wire,
+                              &h_contract,
+                              &coin_pub,
+                              coin_pk_sig,
+                              &coin_pk->key,
+                              timestamp,
+                              cmd->details.deposit.transaction_id,
+                              &merchant_pub,
+                              refund_deadline,
+                              &coin_sig,
+                              &deposit_cb,
+                              is);
+      if (NULL == cmd->details.deposit.dh)
+      {
+        GNUNET_break (0);
+        json_decref (wire);
+        fail (is);
+        return;
+      }
+      json_decref (wire);
+      trigger_context_task ();
+      return;
+    }
+  case OC_REFRESH_MELT:
+    {
+      unsigned int num_melted_coins;
+      unsigned int num_fresh_coins;
+
+      cmd->details.refresh_melt.noreveal_index = UINT16_MAX;
+      for (num_melted_coins=0;
+           NULL != cmd->details.refresh_melt.melted_coins[num_melted_coins].amount;
+           num_melted_coins++) ;
+      for (num_fresh_coins=0;
+           NULL != cmd->details.refresh_melt.fresh_amounts[num_fresh_coins];
+           num_fresh_coins++) ;
+
+      cmd->details.refresh_melt.fresh_pks
+        = GNUNET_new_array (num_fresh_coins,
+                            const struct TALER_EXCHANGE_DenomPublicKey *);
+      {
+        struct TALER_CoinSpendPrivateKeyP melt_privs[num_melted_coins];
+        struct TALER_Amount melt_amounts[num_melted_coins];
+        struct TALER_DenominationSignature melt_sigs[num_melted_coins];
+        struct TALER_EXCHANGE_DenomPublicKey melt_pks[num_melted_coins];
+        struct TALER_EXCHANGE_DenomPublicKey fresh_pks[num_fresh_coins];
+        unsigned int i;
+
+        for (i=0;i<num_melted_coins;i++)
+        {
+          const struct MeltDetails *md = &cmd->details.refresh_melt.melted_coins[i];
+          ref = find_command (is,
+                              md->coin_ref);
+          GNUNET_assert (NULL != ref);
+          GNUNET_assert (OC_WITHDRAW_SIGN == ref->oc);
+
+          melt_privs[i] = ref->details.reserve_withdraw.coin_priv;
+          if (GNUNET_OK !=
+              TALER_string_to_amount (md->amount,
+                                      &melt_amounts[i]))
+          {
+            GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                        "Failed to parse amount `%s' at %u\n",
+                        md->amount,
+                        is->ip);
+            fail (is);
+            return;
+          }
+          melt_sigs[i] = ref->details.reserve_withdraw.sig;
+          melt_pks[i] = *ref->details.reserve_withdraw.pk;
+        }
+        for (i=0;i<num_fresh_coins;i++)
+        {
+          if (GNUNET_OK !=
+              TALER_string_to_amount (cmd->details.refresh_melt.fresh_amounts[i],
+                                      &amount))
+          {
+            GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                        "Failed to parse amount `%s' at %u\n",
+                        cmd->details.reserve_withdraw.amount,
+                        is->ip);
+            fail (is);
+            return;
+          }
+          cmd->details.refresh_melt.fresh_pks[i]
+            = find_pk (is->keys,
+                       &amount);
+          fresh_pks[i] = *cmd->details.refresh_melt.fresh_pks[i];
+        }
+        cmd->details.refresh_melt.refresh_data
+          = TALER_EXCHANGE_refresh_prepare (num_melted_coins,
+                                        melt_privs,
+                                        melt_amounts,
+                                        melt_sigs,
+                                        melt_pks,
+                                        GNUNET_YES,
+                                        num_fresh_coins,
+                                        fresh_pks,
+                                        &cmd->details.refresh_melt.refresh_data_length);
+        if (NULL == cmd->details.refresh_melt.refresh_data)
+        {
+          GNUNET_break (0);
+          fail (is);
+          return;
+        }
+        cmd->details.refresh_melt.rmh
+          = TALER_EXCHANGE_refresh_melt (exchange,
+                                     cmd->details.refresh_melt.refresh_data_length,
+                                     cmd->details.refresh_melt.refresh_data,
+                                     &melt_cb,
+                                     is);
+        if (NULL == cmd->details.refresh_melt.rmh)
+        {
+          GNUNET_break (0);
+          fail (is);
+          return;
+        }
+      }
+    }
+    trigger_context_task ();
+    return;
+  case OC_REFRESH_REVEAL:
+    ref = find_command (is,
+                        cmd->details.refresh_reveal.melt_ref);
+    cmd->details.refresh_reveal.rrh
+      = TALER_EXCHANGE_refresh_reveal (exchange,
+                                   ref->details.refresh_melt.refresh_data_length,
+                                   ref->details.refresh_melt.refresh_data,
+                                   ref->details.refresh_melt.noreveal_index,
+                                   &reveal_cb,
+                                   is);
+    if (NULL == cmd->details.refresh_reveal.rrh)
+    {
+      GNUNET_break (0);
+      fail (is);
+      return;
+    }
+    trigger_context_task ();
+    return;
+  case OC_REFRESH_LINK:
+    /* find reveal command */
+    ref = find_command (is,
+                        cmd->details.refresh_link.reveal_ref);
+    /* find melt command */
+    ref = find_command (is,
+                        ref->details.refresh_reveal.melt_ref);
+    /* find reserve_withdraw command */
+    {
+      unsigned int idx;
+      const struct MeltDetails *md;
+      unsigned int num_melted_coins;
+
+      for (num_melted_coins=0;
+           NULL != ref->details.refresh_melt.melted_coins[num_melted_coins].amount;
+           num_melted_coins++) ;
+      idx = cmd->details.refresh_link.coin_idx;
+      GNUNET_assert (idx < num_melted_coins);
+      md = &ref->details.refresh_melt.melted_coins[idx];
+      ref = find_command (is,
+                          md->coin_ref);
+    }
+    GNUNET_assert (OC_WITHDRAW_SIGN == ref->oc);
+    /* finally, use private key from withdraw sign command */
+    cmd->details.refresh_link.rlh
+      = TALER_EXCHANGE_refresh_link (exchange,
+                                 &ref->details.reserve_withdraw.coin_priv,
+                                 &link_cb,
+                                 is);
+    if (NULL == cmd->details.refresh_link.rlh)
+    {
+      GNUNET_break (0);
+      fail (is);
+      return;
+    }
+    trigger_context_task ();
+    return;
+  case OC_WIRE:
+    cmd->details.wire.wh = TALER_EXCHANGE_wire (exchange,
+                                            &wire_cb,
+                                            is);
+    trigger_context_task ();
+    return;
+  case OC_WIRE_DEPOSITS:
+    if (NULL != cmd->details.wire_deposits.wtid_ref)
+    {
+      ref = find_command (is,
+                          cmd->details.wire_deposits.wtid_ref);
+      GNUNET_assert (NULL != ref);
+      cmd->details.wire_deposits.wtid = ref->details.deposit_wtid.wtid;
+    }
+    cmd->details.wire_deposits.wdh
+      = TALER_EXCHANGE_wire_deposits (exchange,
+                                  &cmd->details.wire_deposits.wtid,
+                                  &wire_deposits_cb,
+                                  is);
+    trigger_context_task ();
+    return;
+  case OC_DEPOSIT_WTID:
+    {
+      struct GNUNET_HashCode h_wire;
+      struct GNUNET_HashCode h_contract;
+      json_t *wire;
+      json_t *contract;
+      const struct Command *coin;
+      struct TALER_CoinSpendPublicKeyP coin_pub;
+
+      ref = find_command (is,
+                          cmd->details.deposit_wtid.deposit_ref);
+      GNUNET_assert (NULL != ref);
+      coin = find_command (is,
+                           ref->details.deposit.coin_ref);
+      GNUNET_assert (NULL != coin);
+      switch (coin->oc)
+      {
+      case OC_WITHDRAW_SIGN:
+        GNUNET_CRYPTO_eddsa_key_get_public (&coin->details.reserve_withdraw.coin_priv.eddsa_priv,
+                                            &coin_pub.eddsa_pub);
+        break;
+      case OC_REFRESH_REVEAL:
+        {
+          const struct FreshCoin *fc;
+          unsigned int idx;
+
+          idx = ref->details.deposit.coin_idx;
+          GNUNET_assert (idx < coin->details.refresh_reveal.num_fresh_coins);
+          fc = &coin->details.refresh_reveal.fresh_coins[idx];
+
+          GNUNET_CRYPTO_eddsa_key_get_public (&fc->coin_priv.eddsa_priv,
+                                              &coin_pub.eddsa_pub);
+        }
+        break;
+      default:
+        GNUNET_assert (0);
+      }
+
+      wire = json_loads (ref->details.deposit.wire_details,
+                         JSON_REJECT_DUPLICATES,
+                         NULL);
+      GNUNET_assert (NULL != wire);
+      TALER_hash_json (wire,
+                       &h_wire);
+      json_decref (wire);
+      contract = json_loads (ref->details.deposit.contract,
+                             JSON_REJECT_DUPLICATES,
+                             NULL);
+      GNUNET_assert (NULL != contract);
+      TALER_hash_json (contract,
+                       &h_contract);
+      json_decref (contract);
+      cmd->details.deposit_wtid.dwh
+        = TALER_EXCHANGE_deposit_wtid (exchange,
+                                   &ref->details.deposit.merchant_priv,
+                                   &h_wire,
+                                   &h_contract,
+                                   &coin_pub,
+                                   ref->details.deposit.transaction_id,
+                                   &deposit_wtid_cb,
+                                   is);
+      trigger_context_task ();
+    }
+    return;
+  default:
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unknown instruction %d at %u (%s)\n",
+                cmd->oc,
+                is->ip,
+                cmd->label);
+    fail (is);
+    return;
+  }
+}
+
+
+/**
+ * Function run when the test terminates (good or bad).
+ * Cleans up our state.
+ *
+ * @param cls the interpreter state.
+ * @param tc unused
+ */
+static void
+do_shutdown (void *cls,
+             const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  struct InterpreterState *is = cls;
+  struct Command *cmd;
+  unsigned int i;
+
+  shutdown_task = NULL;
+  for (i=0;OC_END != (cmd = &is->commands[i])->oc;i++)
+  {
+    switch (cmd->oc)
+    {
+    case OC_END:
+      GNUNET_assert (0);
+      break;
+    case OC_ADMIN_ADD_INCOMING:
+      if (NULL != cmd->details.admin_add_incoming.aih)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_admin_add_incoming_cancel (cmd->details.admin_add_incoming.aih);
+        cmd->details.admin_add_incoming.aih = NULL;
+      }
+      break;
+    case OC_WITHDRAW_STATUS:
+      if (NULL != cmd->details.reserve_status.wsh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_reserve_status_cancel (cmd->details.reserve_status.wsh);
+        cmd->details.reserve_status.wsh = NULL;
+      }
+      break;
+    case OC_WITHDRAW_SIGN:
+      if (NULL != cmd->details.reserve_withdraw.wsh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_reserve_withdraw_cancel (cmd->details.reserve_withdraw.wsh);
+        cmd->details.reserve_withdraw.wsh = NULL;
+      }
+      if (NULL != cmd->details.reserve_withdraw.sig.rsa_signature)
+      {
+        GNUNET_CRYPTO_rsa_signature_free (cmd->details.reserve_withdraw.sig.rsa_signature);
+        cmd->details.reserve_withdraw.sig.rsa_signature = NULL;
+      }
+      if (NULL != cmd->details.reserve_withdraw.blinding_key.rsa_blinding_key)
+      {
+        GNUNET_CRYPTO_rsa_blinding_key_free (cmd->details.reserve_withdraw.blinding_key.rsa_blinding_key);
+        cmd->details.reserve_withdraw.blinding_key.rsa_blinding_key = NULL;
+      }
+      break;
+    case OC_DEPOSIT:
+      if (NULL != cmd->details.deposit.dh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_deposit_cancel (cmd->details.deposit.dh);
+        cmd->details.deposit.dh = NULL;
+      }
+      break;
+    case OC_REFRESH_MELT:
+      if (NULL != cmd->details.refresh_melt.rmh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_refresh_melt_cancel (cmd->details.refresh_melt.rmh);
+        cmd->details.refresh_melt.rmh = NULL;
+      }
+      GNUNET_free_non_null (cmd->details.refresh_melt.fresh_pks);
+      cmd->details.refresh_melt.fresh_pks = NULL;
+      GNUNET_free_non_null (cmd->details.refresh_melt.refresh_data);
+      cmd->details.refresh_melt.refresh_data = NULL;
+      cmd->details.refresh_melt.refresh_data_length = 0;
+      break;
+    case OC_REFRESH_REVEAL:
+      if (NULL != cmd->details.refresh_reveal.rrh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_refresh_reveal_cancel (cmd->details.refresh_reveal.rrh);
+        cmd->details.refresh_reveal.rrh = NULL;
+      }
+      {
+        unsigned int j;
+        struct FreshCoin *fresh_coins;
+
+        fresh_coins = cmd->details.refresh_reveal.fresh_coins;
+        for (j=0;j<cmd->details.refresh_reveal.num_fresh_coins;j++)
+          GNUNET_CRYPTO_rsa_signature_free (fresh_coins[j].sig.rsa_signature);
+      }
+      GNUNET_free_non_null (cmd->details.refresh_reveal.fresh_coins);
+      cmd->details.refresh_reveal.fresh_coins = NULL;
+      cmd->details.refresh_reveal.num_fresh_coins = 0;
+      break;
+    case OC_REFRESH_LINK:
+      if (NULL != cmd->details.refresh_link.rlh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_refresh_link_cancel (cmd->details.refresh_link.rlh);
+        cmd->details.refresh_link.rlh = NULL;
+      }
+      break;
+    case OC_WIRE:
+      if (NULL != cmd->details.wire.wh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_wire_cancel (cmd->details.wire.wh);
+        cmd->details.wire.wh = NULL;
+      }
+      break;
+    case OC_WIRE_DEPOSITS:
+      if (NULL != cmd->details.wire_deposits.wdh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_wire_deposits_cancel (cmd->details.wire_deposits.wdh);
+        cmd->details.wire_deposits.wdh = NULL;
+      }
+      break;
+    case OC_DEPOSIT_WTID:
+      if (NULL != cmd->details.deposit_wtid.dwh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    "Command %u (%s) did not complete\n",
+                    i,
+                    cmd->label);
+        TALER_EXCHANGE_deposit_wtid_cancel (cmd->details.deposit_wtid.dwh);
+        cmd->details.deposit_wtid.dwh = NULL;
+      }
+      break;
+    default:
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Unknown instruction %d at %u (%s)\n",
+                  cmd->oc,
+                  i,
+                  cmd->label);
+      break;
+    }
+  }
+  if (NULL != is->task)
+  {
+    GNUNET_SCHEDULER_cancel (is->task);
+    is->task = NULL;
+  }
+  GNUNET_free (is);
+  if (NULL != ctx_task)
+  {
+    GNUNET_SCHEDULER_cancel (ctx_task);
+    ctx_task = NULL;
+  }
+  if (NULL != exchange)
+  {
+    TALER_EXCHANGE_disconnect (exchange);
+    exchange = NULL;
+  }
+  if (NULL != ctx)
+  {
+    TALER_EXCHANGE_fini (ctx);
+    ctx = NULL;
+  }
+}
+
+
+/**
+ * Functions of this type are called to provide the retrieved signing and
+ * denomination keys of the exchange.  No TALER_EXCHANGE_*() functions should be called
+ * in this callback.
+ *
+ * @param cls closure
+ * @param keys information about keys of the exchange
+ */
+static void
+cert_cb (void *cls,
+         const struct TALER_EXCHANGE_Keys *keys)
+{
+  struct InterpreterState *is = cls;
+
+  /* check that keys is OK */
+#define ERR(cond) do { if(!(cond)) break; GNUNET_break (0); GNUNET_SCHEDULER_shutdown(); return; } while (0)
+  ERR (NULL == keys);
+  ERR (0 == keys->num_sign_keys);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Read %u signing keys\n",
+              keys->num_sign_keys);
+  ERR (0 == keys->num_denom_keys);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Read %u denomination keys\n",
+              keys->num_denom_keys);
+#undef ERR
+
+  /* run actual tests via interpreter-loop */
+  is->keys = keys;
+  is->task = GNUNET_SCHEDULER_add_now (&interpreter_run,
+                                       is);
+}
+
+
+/**
+ * Task that runs the context's event loop with the GNUnet scheduler.
+ *
+ * @param cls unused
+ * @param tc scheduler context (unused)
+ */
+static void
+context_task (void *cls,
+              const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  long timeout;
+  int max_fd;
+  fd_set read_fd_set;
+  fd_set write_fd_set;
+  fd_set except_fd_set;
+  struct GNUNET_NETWORK_FDSet *rs;
+  struct GNUNET_NETWORK_FDSet *ws;
+  struct GNUNET_TIME_Relative delay;
+
+  ctx_task = NULL;
+  TALER_EXCHANGE_perform (ctx);
+  max_fd = -1;
+  timeout = -1;
+  FD_ZERO (&read_fd_set);
+  FD_ZERO (&write_fd_set);
+  FD_ZERO (&except_fd_set);
+  TALER_EXCHANGE_get_select_info (ctx,
+                              &read_fd_set,
+                              &write_fd_set,
+                              &except_fd_set,
+                              &max_fd,
+                              &timeout);
+  if (timeout >= 0)
+    delay = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS,
+                                           timeout);
+  else
+    delay = GNUNET_TIME_UNIT_FOREVER_REL;
+  rs = GNUNET_NETWORK_fdset_create ();
+  GNUNET_NETWORK_fdset_copy_native (rs,
+                                    &read_fd_set,
+                                    max_fd + 1);
+  ws = GNUNET_NETWORK_fdset_create ();
+  GNUNET_NETWORK_fdset_copy_native (ws,
+                                    &write_fd_set,
+                                    max_fd + 1);
+  ctx_task = GNUNET_SCHEDULER_add_select (GNUNET_SCHEDULER_PRIORITY_DEFAULT,
+                                          delay,
+                                          rs,
+                                          ws,
+                                          &context_task,
+                                          cls);
+  GNUNET_NETWORK_fdset_destroy (rs);
+  GNUNET_NETWORK_fdset_destroy (ws);
+}
+
+
+/**
+ * Main function that will be run by the scheduler.
+ *
+ * @param cls closure
+ * @param args remaining command-line arguments
+ * @param cfgfile name of the configuration file used (for saving, can be NULL!)
+ * @param config configuration
+ */
+static void
+run (void *cls,
+     const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  struct InterpreterState *is;
+  static struct MeltDetails melt_coins_1[] = {
+    { .amount = "EUR:4",
+      .coin_ref = "refresh-withdraw-coin-1" },
+    { NULL, NULL }
+  };
+  static const char *melt_fresh_amounts_1[] = {
+    "EUR:1",
+    "EUR:1",
+    "EUR:1",
+    "EUR:0.1",
+    "EUR:0.1",
+    "EUR:0.1",
+    "EUR:0.1",
+    "EUR:0.1",
+    "EUR:0.1",
+    "EUR:0.1",
+    "EUR:0.1",
+    "EUR:0.01",
+    "EUR:0.01",
+    "EUR:0.01",
+    "EUR:0.01",
+    "EUR:0.01",
+    "EUR:0.01",
+    /* with 0.01 withdraw fees (except for 1ct coins),
+       this totals up to exactly EUR:3.97, and with
+       the 0.03 refresh fee, to EUR:4.0*/
+    NULL
+  };
+  static struct Command commands[] =
+  {
+    /* *************** start of /wire testing ************** */
+
+#if WIRE_TEST
+    { .oc = OC_WIRE,
+      .label = "wire-test",
+      /* /wire/test replies with a 302 redirect */
+      .expected_response_code = MHD_HTTP_FOUND,
+      .details.wire.format = "test" },
+#endif
+#if WIRE_SEPA
+    { .oc = OC_WIRE,
+      .label = "wire-sepa",
+      /* /wire/sepa replies with a 200 redirect */
+      .expected_response_code = MHD_HTTP_OK,
+      .details.wire.format = "sepa" },
+#endif
+    /* *************** end of /wire testing ************** */
+
+#if WIRE_TEST
+    /* None of this works if 'test' is not allowed as we do
+       /admin/add/incoming with format 'test' */
+
+    /* Fill reserve with EUR:5.01, as withdraw fee is 1 ct per config */
+    { .oc = OC_ADMIN_ADD_INCOMING,
+      .label = "create-reserve-1",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.admin_add_incoming.wire = "{ \"type\":\"TEST\", \"bank\":\"source bank\", \"account_number\":42 }",
+      .details.admin_add_incoming.amount = "EUR:5.01" },
+    /* Withdraw a 5 EUR coin, at fee of 1 ct */
+    { .oc = OC_WITHDRAW_SIGN,
+      .label = "withdraw-coin-1",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.reserve_withdraw.reserve_reference = "create-reserve-1",
+      .details.reserve_withdraw.amount = "EUR:5" },
+    /* Check that deposit and withdraw operation are in history, and
+       that the balance is now at zero */
+    { .oc = OC_WITHDRAW_STATUS,
+      .label = "withdraw-status-1",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.reserve_status.reserve_reference = "create-reserve-1",
+      .details.reserve_status.expected_balance = "EUR:0" },
+    /* Try to deposit the 5 EUR coin (in full) */
+    { .oc = OC_DEPOSIT,
+      .label = "deposit-simple",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.deposit.amount = "EUR:5",
+      .details.deposit.coin_ref = "withdraw-coin-1",
+      .details.deposit.wire_details = "{ \"type\":\"TEST\", \"bank\":\"dest bank\", \"account_number\":42 }",
+      .details.deposit.contract = "{ \"items\": [ { \"name\":\"ice cream\", \"value\":1 } ] }",
+      .details.deposit.transaction_id = 1 },
+
+    /* Try to overdraw funds ... */
+    { .oc = OC_WITHDRAW_SIGN,
+      .label = "withdraw-coin-2",
+      .expected_response_code = MHD_HTTP_PAYMENT_REQUIRED,
+      .details.reserve_withdraw.reserve_reference = "create-reserve-1",
+      .details.reserve_withdraw.amount = "EUR:5" },
+
+    /* Try to double-spend the 5 EUR coin with different wire details */
+    { .oc = OC_DEPOSIT,
+      .label = "deposit-double-1",
+      .expected_response_code = MHD_HTTP_FORBIDDEN,
+      .details.deposit.amount = "EUR:5",
+      .details.deposit.coin_ref = "withdraw-coin-1",
+      .details.deposit.wire_details = "{ \"type\":\"TEST\", \"bank\":\"dest bank\", \"account_number\":43 }",
+      .details.deposit.contract = "{ \"items\": [ { \"name\":\"ice cream\", \"value\":1 } ] }",
+      .details.deposit.transaction_id = 1 },
+    /* Try to double-spend the 5 EUR coin at the same merchant (but different
+       transaction ID) */
+    { .oc = OC_DEPOSIT,
+      .label = "deposit-double-2",
+      .expected_response_code = MHD_HTTP_FORBIDDEN,
+      .details.deposit.amount = "EUR:5",
+      .details.deposit.coin_ref = "withdraw-coin-1",
+      .details.deposit.wire_details = "{ \"type\":\"TEST\", \"bank\":\"dest bank\", \"account_number\":42 }",
+      .details.deposit.contract = "{ \"items\": [ { \"name\":\"ice cream\", \"value\":1 } ] }",
+      .details.deposit.transaction_id = 2 },
+    /* Try to double-spend the 5 EUR coin at the same merchant (but different
+       contract) */
+    { .oc = OC_DEPOSIT,
+      .label = "deposit-double-3",
+      .expected_response_code = MHD_HTTP_FORBIDDEN,
+      .details.deposit.amount = "EUR:5",
+      .details.deposit.coin_ref = "withdraw-coin-1",
+      .details.deposit.wire_details = "{ \"type\":\"TEST\", \"bank\":\"dest bank\", \"account_number\":42 }",
+      .details.deposit.contract = "{ \"items\":[{ \"name\":\"ice cream\", \"value\":2 } ] }",
+      .details.deposit.transaction_id = 1 },
+
+    /* ***************** /refresh testing ******************** */
+
+    /* Fill reserve with EUR:5.01, as withdraw fee is 1 ct */
+    { .oc = OC_ADMIN_ADD_INCOMING,
+      .label = "refresh-create-reserve-1",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.admin_add_incoming.wire = "{ \"type\":\"TEST\", \"bank\":\"source bank\", \"account_number\":424 }",
+      .details.admin_add_incoming.amount = "EUR:5.01" },
+    /* Withdraw a 5 EUR coin, at fee of 1 ct */
+    { .oc = OC_WITHDRAW_SIGN,
+      .label = "refresh-withdraw-coin-1",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.reserve_withdraw.reserve_reference = "refresh-create-reserve-1",
+      .details.reserve_withdraw.amount = "EUR:5" },
+    /* Try to partially spend (deposit) 1 EUR of the 5 EUR coin (in full)
+       (merchant would receive EUR:0.99 due to 1 ct deposit fee) */
+    { .oc = OC_DEPOSIT,
+      .label = "refresh-deposit-partial",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.deposit.amount = "EUR:1",
+      .details.deposit.coin_ref = "refresh-withdraw-coin-1",
+      .details.deposit.wire_details = "{ \"type\":\"TEST\", \"bank\":\"dest bank\", \"account_number\":42 }",
+      .details.deposit.contract = "{ \"items\" : [ { \"name\":\"ice cream\", \"value\":\"EUR:1\" } ] }",
+      .details.deposit.transaction_id = 42421 },
+
+    /* Melt the rest of the coin's value (EUR:4.00 = 3x EUR:1.03 + 7x EUR:0.13) */
+
+    { .oc = OC_REFRESH_MELT,
+      .label = "refresh-melt-1",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.refresh_melt.melted_coins = melt_coins_1,
+      .details.refresh_melt.fresh_amounts = melt_fresh_amounts_1 },
+
+
+    /* Complete (successful) melt operation, and withdraw the coins */
+    { .oc = OC_REFRESH_REVEAL,
+      .label = "refresh-reveal-1",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.refresh_reveal.melt_ref = "refresh-melt-1" },
+
+    /* Test that /refresh/link works */
+    { .oc = OC_REFRESH_LINK,
+      .label = "refresh-link-1",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.refresh_link.reveal_ref = "refresh-reveal-1" },
+
+
+    /* Test successfully spending coins from the refresh operation:
+       first EUR:1 */
+    { .oc = OC_DEPOSIT,
+      .label = "refresh-deposit-refreshed-1a",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.deposit.amount = "EUR:1",
+      .details.deposit.coin_ref = "refresh-reveal-1",
+      .details.deposit.coin_idx = 0,
+      .details.deposit.wire_details = "{ \"type\":\"TEST\", \"bank\":\"dest bank\", \"account_number\":42 }",
+      .details.deposit.contract = "{ \"items\": [ { \"name\":\"ice cream\", \"value\":3 } ] }",
+      .details.deposit.transaction_id = 2 },
+
+    /* Test successfully spending coins from the refresh operation:
+       finally EUR:0.1 */
+    { .oc = OC_DEPOSIT,
+      .label = "refresh-deposit-refreshed-1b",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.deposit.amount = "EUR:0.1",
+      .details.deposit.coin_ref = "refresh-reveal-1",
+      .details.deposit.coin_idx = 4,
+      .details.deposit.wire_details = "{ \"type\":\"TEST\", \"bank\":\"dest bank\", \"account_number\":42 }",
+      .details.deposit.contract = "{ \"items\": [ { \"name\":\"ice cream\", \"value\":3 } ] }",
+      .details.deposit.transaction_id = 2 },
+
+    /* Test running a failing melt operation (same operation again must fail) */
+    { .oc = OC_REFRESH_MELT,
+      .label = "refresh-melt-failing",
+      .expected_response_code = MHD_HTTP_FORBIDDEN,
+      .details.refresh_melt.melted_coins = melt_coins_1,
+      .details.refresh_melt.fresh_amounts = melt_fresh_amounts_1 },
+
+    // FIXME: also test with coin that was already melted
+    // (signature differs from coin that was deposited...)
+    /* *************** end of /refresh testing ************** */
+
+    /* ************** Test tracking API ******************** */
+    /* Try resolving a deposit's WTID, as we never triggered
+       execution of transactions, the answer should be that
+       the exchange knows about the deposit, but has no WTID yet. */
+    { .oc = OC_DEPOSIT_WTID,
+      .label = "deposit-wtid-found",
+      .expected_response_code = MHD_HTTP_ACCEPTED,
+      .details.deposit_wtid.deposit_ref = "deposit-simple" },
+    /* Try resolving a deposit's WTID for a failed deposit.
+       As the deposit failed, the answer should be that
+       the exchange does NOT know about the deposit. */
+    { .oc = OC_DEPOSIT_WTID,
+      .label = "deposit-wtid-failing",
+      .expected_response_code = MHD_HTTP_NOT_FOUND,
+      .details.deposit_wtid.deposit_ref = "deposit-double-2" },
+    /* Try resolving an undefined (all zeros) WTID; this
+       should fail as obviously the exchange didn't use that
+       WTID value for any transaction. */
+    { .oc = OC_WIRE_DEPOSITS,
+      .label = "wire-deposit-failing",
+      .expected_response_code = MHD_HTTP_NOT_FOUND },
+
+    /* TODO: trigger aggregation logic and then check the
+       cases where tracking succeeds! */
+
+    /* ************** End of tracking API testing************* */
+
+
+#endif
+
+    { .oc = OC_END }
+  };
+
+  is = GNUNET_new (struct InterpreterState);
+  is->commands = commands;
+
+  ctx = TALER_EXCHANGE_init ();
+  GNUNET_assert (NULL != ctx);
+  ctx_task = GNUNET_SCHEDULER_add_now (&context_task,
+                                       ctx);
+  exchange = TALER_EXCHANGE_connect (ctx,
+                             "http://localhost:8081",
+                             &cert_cb, is,
+                             TALER_EXCHANGE_OPTION_END);
+  GNUNET_assert (NULL != exchange);
+  shutdown_task
+    = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply
+                                    (GNUNET_TIME_UNIT_SECONDS, 150),
+                                    &do_shutdown, is);
+}
+
+
+/**
+ * Main function for the testcase for the exchange API.
+ *
+ * @param argc expected to be 1
+ * @param argv expected to only contain the program name
+ */
+int
+main (int argc,
+      char * const *argv)
+{
+  struct GNUNET_OS_Process *proc;
+  struct GNUNET_OS_Process *exchanged;
+
+  GNUNET_log_setup ("test-exchange-api",
+                    "WARNING",
+                    NULL);
+  proc = GNUNET_OS_start_process (GNUNET_NO,
+                                  GNUNET_OS_INHERIT_STD_ALL,
+                                  NULL, NULL, NULL,
+                                  "taler-exchange-keyup",
+                                  "taler-exchange-keyup",
+                                  "-d", "test-exchange-home",
+                                  "-m", "test-exchange-home/master.priv",
+                                  NULL);
+  GNUNET_OS_process_wait (proc);
+  GNUNET_OS_process_destroy (proc);
+  exchanged = GNUNET_OS_start_process (GNUNET_NO,
+                                   GNUNET_OS_INHERIT_STD_ALL,
+                                   NULL, NULL, NULL,
+                                   "taler-exchange-httpd",
+                                   "taler-exchange-httpd",
+                                   "-d", "test-exchange-home",
+                                   NULL);
+  /* give child time to start and bind against the socket */
+  fprintf (stderr, "Waiting for taler-exchange-httpd to be ready");
+  do
+    {
+      fprintf (stderr, ".");
+      sleep (1);
+    }
+  while (0 != system ("wget -q -t 1 -T 1 http://127.0.0.1:8081/keys -o /dev/null -O /dev/null"));
+  fprintf (stderr, "\n");
+  result = GNUNET_SYSERR;
+  GNUNET_SCHEDULER_run (&run, NULL);
+  GNUNET_OS_process_kill (exchanged,
+                          SIGTERM);
+  GNUNET_OS_process_wait (exchanged);
+  GNUNET_OS_process_destroy (exchanged);
+  return (GNUNET_OK == result) ? 0 : 1;
+}
+
+/* end of test_exchange_api.c */