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diff --git a/src/bank-lib/fakebank.h b/src/bank-lib/fakebank.h
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+/*
+  This file is part of TALER
+  (C) 2016-2023 Taler Systems SA
+
+  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,
+  see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file bank-lib/fakebank.h
+ * @brief general state of the fakebank
+ * @author Christian Grothoff <christian@grothoff.org>
+ */
+#ifndef FAKEBANK_H
+#define FAKEBANK_H
+
+#include "taler_fakebank_lib.h"
+#include "taler_bank_service.h"
+#include "taler_mhd_lib.h"
+#include <gnunet/gnunet_mhd_compat.h>
+
+
+/**
+ * How long are exchange base URLs allowed to be at most?
+ * Set to a relatively low number as this does contribute
+ * significantly to our RAM consumption.
+ */
+#define MAX_URL_LEN 64
+
+
+/**
+ * Maximum POST request size.
+ */
+#define REQUEST_BUFFER_MAX (4 * 1024)
+
+
+/**
+ * Per account information.
+ */
+struct Account;
+
+
+/**
+ * Types of long polling activities.
+ */
+enum LongPollType
+{
+  /**
+   * Transfer TO the exchange.
+   */
+  LP_CREDIT,
+
+  /**
+   * Transfer FROM the exchange.
+   */
+  LP_DEBIT,
+
+  /**
+   * Withdraw operation completion/abort.
+   */
+  LP_WITHDRAW
+
+};
+
+/**
+ * Client waiting for activity on this account.
+ */
+struct LongPoller
+{
+
+  /**
+   * Kept in a DLL.
+   */
+  struct LongPoller *next;
+
+  /**
+   * Kept in a DLL.
+   */
+  struct LongPoller *prev;
+
+  /**
+   * Fakebank this long poller belongs with.
+   */
+  struct TALER_FAKEBANK_Handle *h;
+
+  /**
+   * Account this long poller is waiting on.
+   */
+  struct Account *account;
+
+  /**
+   * Withdraw operation we are waiting on,
+   * only if @e type is #LP_WITHDRAW, otherwise NULL.
+   */
+  const struct WithdrawalOperation *wo;
+
+  /**
+   * Entry in the heap for this long poller.
+   */
+  struct GNUNET_CONTAINER_HeapNode *hn;
+
+  /**
+   * Client that is waiting for transactions.
+   */
+  struct MHD_Connection *conn;
+
+  /**
+   * When will this long poller time out?
+   */
+  struct GNUNET_TIME_Absolute timeout;
+
+  /**
+   * What does the @e connection wait for?
+   */
+  enum LongPollType type;
+
+};
+
+
+/**
+ * Details about a transcation we (as the simulated bank) received.
+ */
+struct Transaction;
+
+
+/**
+ * Information we keep per withdraw operation.
+ */
+struct WithdrawalOperation
+{
+  /**
+   * Unique (random) operation ID.
+   */
+  struct GNUNET_ShortHashCode wopid;
+
+  /**
+   * Debited account.
+   */
+  struct Account *debit_account;
+
+  /**
+   * Target exchange account, or NULL if unknown.
+   */
+  const struct Account *exchange_account;
+
+  /**
+   * RowID of the resulting transaction, if any. Otherwise 0.
+   */
+  uint64_t row_id;
+
+  /**
+   * Amount transferred.
+   */
+  struct TALER_Amount amount;
+
+  /**
+   * Public key of the reserve, wire transfer subject.
+   */
+  struct TALER_ReservePublicKeyP reserve_pub;
+
+  /**
+   * When was the transaction made? 0 if not yet.
+   */
+  struct GNUNET_TIME_Timestamp timestamp;
+
+  /**
+   * Was the withdrawal aborted?
+   */
+  bool aborted;
+
+  /**
+   * Did the bank confirm the withdrawal?
+   */
+  bool confirmation_done;
+
+  /**
+   * Is @e reserve_pub initialized?
+   */
+  bool selection_done;
+
+};
+
+
+/**
+ * Per account information.
+ */
+struct Account
+{
+
+  /**
+   * Inbound transactions for this account in a MDLL.
+   */
+  struct Transaction *in_head;
+
+  /**
+   * Inbound transactions for this account in a MDLL.
+   */
+  struct Transaction *in_tail;
+
+  /**
+   * Outbound transactions for this account in a MDLL.
+   */
+  struct Transaction *out_head;
+
+  /**
+   * Outbound transactions for this account in a MDLL.
+   */
+  struct Transaction *out_tail;
+
+  /**
+   * Kept in a DLL.
+   */
+  struct LongPoller *lp_head;
+
+  /**
+   * Kept in a DLL.
+   */
+  struct LongPoller *lp_tail;
+
+  /**
+   * Account name (string, not payto!)
+   */
+  char *account_name;
+
+  /**
+   * Receiver name for payto:// URIs.
+   */
+  char *receiver_name;
+
+  /**
+   * Payto URI for this account.
+   */
+  char *payto_uri;
+
+  /**
+   * Password set for the account (if any).
+   */
+  char *password;
+
+  /**
+   * Current account balance.
+   */
+  struct TALER_Amount balance;
+
+  /**
+   * true if the balance is negative.
+   */
+  bool is_negative;
+
+};
+
+
+/**
+ * Details about a transcation we (as the simulated bank) received.
+ */
+struct Transaction
+{
+  /**
+   * We store inbound transactions in a MDLL.
+   */
+  struct Transaction *next_in;
+
+  /**
+   * We store inbound transactions in a MDLL.
+   */
+  struct Transaction *prev_in;
+
+  /**
+   * We store outbound transactions in a MDLL.
+   */
+  struct Transaction *next_out;
+
+  /**
+   * We store outbound transactions in a MDLL.
+   */
+  struct Transaction *prev_out;
+
+  /**
+   * Amount to be transferred.
+   */
+  struct TALER_Amount amount;
+
+  /**
+   * Account to debit.
+   */
+  struct Account *debit_account;
+
+  /**
+   * Account to credit.
+   */
+  struct Account *credit_account;
+
+  /**
+   * Random unique identifier for the request.
+   * Used to detect idempotent requests.
+   */
+  struct GNUNET_HashCode request_uid;
+
+  /**
+   * When did the transaction happen?
+   */
+  struct GNUNET_TIME_Timestamp date;
+
+  /**
+   * Number of this transaction.
+   */
+  uint64_t row_id;
+
+  /**
+   * What does the @e subject contain?
+   */
+  enum
+  {
+    /**
+     * Transfer TO the exchange.
+     */
+    T_CREDIT,
+
+    /**
+     * Transfer FROM the exchange.
+     */
+    T_DEBIT,
+
+    /**
+     * Exchange-to-exchange WAD transfer.
+     */
+    T_WAD,
+  } type;
+
+  /**
+   * Wire transfer subject.
+   */
+  union
+  {
+
+    /**
+     * Used if @e type is T_DEBIT.
+     */
+    struct
+    {
+
+      /**
+       * Subject of the transfer.
+       */
+      struct TALER_WireTransferIdentifierRawP wtid;
+
+      /**
+       * Base URL of the exchange.
+       */
+      char exchange_base_url[MAX_URL_LEN];
+
+    } debit;
+
+    /**
+     * Used if @e type is T_CREDIT.
+     */
+    struct
+    {
+
+      /**
+       * Reserve public key of the credit operation.
+       */
+      struct TALER_ReservePublicKeyP reserve_pub;
+
+    } credit;
+
+    /**
+     * Used if @e type is T_WAD.
+     */
+    struct
+    {
+
+      /**
+       * Subject of the transfer.
+       */
+      struct TALER_WadIdentifierP wad;
+
+      /**
+       * Base URL of the originating exchange.
+       */
+      char origin_base_url[MAX_URL_LEN];
+
+    } wad;
+
+  } subject;
+
+  /**
+   * Has this transaction not yet been subjected to
+   * #TALER_FAKEBANK_check_credit() or #TALER_FAKEBANK_check_debit() and
+   * should thus be counted in #TALER_FAKEBANK_check_empty()?
+   */
+  bool unchecked;
+};
+
+
+/**
+ * Function called to clean up context of a connection.
+ *
+ * @param ctx context to clean up
+ */
+typedef void
+(*ConnectionCleaner)(void *ctx);
+
+/**
+ * Universal context we keep per connection.
+ */
+struct ConnectionContext
+{
+  /**
+   * Function we call upon completion to clean up.
+   */
+  ConnectionCleaner ctx_cleaner;
+
+  /**
+   * Request-handler specific context.
+   */
+  void *ctx;
+};
+
+
+/**
+ * This is the "base" structure for both the /history and the
+ * /history-range API calls.
+ */
+struct HistoryArgs
+{
+
+  /**
+   * Bank account number of the requesting client.
+   */
+  uint64_t account_number;
+
+  /**
+   * Index of the starting transaction, exclusive (!).
+   */
+  uint64_t start_idx;
+
+  /**
+   * Requested number of results and order
+   * (positive: ascending, negative: descending)
+   */
+  int64_t delta;
+
+  /**
+   * Timeout for long polling.
+   */
+  struct GNUNET_TIME_Relative lp_timeout;
+
+  /**
+   * true if starting point was given.
+   */
+  bool have_start;
+
+};
+
+
+/**
+ * Context we keep per history request.
+ */
+struct HistoryContext
+{
+  /**
+   * When does this request time out.
+   */
+  struct GNUNET_TIME_Absolute timeout;
+
+  /**
+   * Client arguments for this request.
+   */
+  struct HistoryArgs ha;
+
+  /**
+   * Account the request is about.
+   */
+  struct Account *acc;
+
+  /**
+   * JSON object we are building to return.
+   */
+  json_t *history;
+
+};
+
+
+/**
+ * Context we keep per get withdrawal operation request.
+ */
+struct WithdrawContext
+{
+  /**
+   * When does this request time out.
+   */
+  struct GNUNET_TIME_Absolute timeout;
+
+  /**
+   * The withdrawal operation this is about.
+   */
+  struct WithdrawalOperation *wo;
+
+};
+
+
+/**
+ * Handle for the fake bank.
+ */
+struct TALER_FAKEBANK_Handle
+{
+  /**
+   * We store transactions in a revolving array.
+   */
+  struct Transaction **transactions;
+
+  /**
+   * HTTP server we run to pretend to be the "test" bank.
+   */
+  struct MHD_Daemon *mhd_bank;
+
+  /**
+   * Task running HTTP server for the "test" bank,
+   * unless we are using a thread pool (then NULL).
+   */
+  struct GNUNET_SCHEDULER_Task *mhd_task;
+
+  /**
+   * Task for expiring long-polling connections,
+   * unless we are using a thread pool (then NULL).
+   */
+  struct GNUNET_SCHEDULER_Task *lp_task;
+
+  /**
+   * Task for expiring long-polling connections, unless we are using the
+   * GNUnet scheduler (then NULL).
+   */
+  pthread_t lp_thread;
+
+  /**
+   * MIN-heap of long pollers, sorted by timeout.
+   */
+  struct GNUNET_CONTAINER_Heap *lp_heap;
+
+  /**
+   * Hashmap of reserve public keys to
+   * `struct Transaction` with that reserve public
+   * key. Used to prevent public-key reuse.
+   */
+  struct GNUNET_CONTAINER_MultiPeerMap *rpubs;
+
+  /**
+   * Hashmap of short hashes (wopids) to
+   * `struct WithdrawalOperation`.
+   * Used to lookup withdrawal operations.
+   */
+  struct GNUNET_CONTAINER_MultiShortmap *wops;
+
+  /**
+   * (Base) URL to suggest for the exchange.  Can
+   * be NULL if there is no suggestion to be made.
+   */
+  char *exchange_url;
+
+  /**
+   * Lock for accessing @a rpubs map.
+   */
+  pthread_mutex_t rpubs_lock;
+
+  /**
+   * Hashmap of hashes of account names to `struct Account`.
+   */
+  struct GNUNET_CONTAINER_MultiHashMap *accounts;
+
+  /**
+   * Lock for accessing @a accounts hash map.
+   */
+  pthread_mutex_t accounts_lock;
+
+  /**
+   * Hashmap of hashes of transaction request_uids to `struct Transaction`.
+   */
+  struct GNUNET_CONTAINER_MultiHashMap *uuid_map;
+
+  /**
+   * Lock for accessing @a uuid_map.
+   */
+  pthread_mutex_t uuid_map_lock;
+
+  /**
+   * Lock for accessing the internals of
+   * accounts and transaction array entries.
+   */
+  pthread_mutex_t big_lock;
+
+  /**
+   * How much money should be put into new accounts
+   * on /register.
+   */
+  struct TALER_Amount signup_bonus;
+
+  /**
+   * Current transaction counter.
+   */
+  uint64_t serial_counter;
+
+  /**
+   * Number of transactions we keep in memory (at most).
+   */
+  uint64_t ram_limit;
+
+  /**
+   * Currency used by the fakebank.
+   */
+  char *currency;
+
+  /**
+   * Hostname of the fakebank.
+   */
+  char *hostname;
+
+  /**
+   * BaseURL of the fakebank.
+   */
+  char *my_baseurl;
+
+  /**
+   * Our port number.
+   */
+  uint16_t port;
+
+#ifdef __linux__
+  /**
+   * Event FD to signal @a lp_thread a change in
+   * @a lp_heap.
+   */
+  int lp_event;
+#else
+  /**
+   * Pipe input to signal @a lp_thread a change in
+   * @a lp_heap.
+   */
+  int lp_event_in;
+
+  /**
+   * Pipe output to signal @a lp_thread a change in
+   * @a lp_heap.
+   */
+  int lp_event_out;
+#endif
+
+  /**
+   * Set to true once we are shutting down.
+   */
+  bool in_shutdown;
+
+  /**
+   * Should we run MHD immediately again?
+   */
+  bool mhd_again;
+
+#if EPOLL_SUPPORT
+  /**
+   * Boxed @e mhd_fd.
+   */
+  struct GNUNET_NETWORK_Handle *mhd_rfd;
+
+  /**
+   * File descriptor to use to wait for MHD.
+   */
+  int mhd_fd;
+#endif
+};
+
+
+/**
+ * Task run whenever HTTP server operations are pending.
+ *
+ * @param cls the `struct TALER_FAKEBANK_Handle`
+ */
+void
+TALER_FAKEBANK_run_mhd_ (void *cls);
+
+
+#endif