-payment router skeleton

4 files changed, 480 insertions, 3 deletions

diff --git a/src/exchange/.gitignore b/src/exchange/.gitignore
index 5818f1717..c12ee0117 100644
--- a/src/exchange/.gitignore
+++ b/src/exchange/.gitignore
@@ -9,3 +9,4 @@ test_taler_exchange_wirewatch-postgres
 test_taler_exchange_httpd_home/.config/taler/account-1.json
 taler-exchange-closer
 taler-exchange-transfer
+taler-exchange-router
diff --git a/src/exchange/Makefile.am b/src/exchange/Makefile.am
index 4d0caad8a..21cc12282 100644
--- a/src/exchange/Makefile.am
+++ b/src/exchange/Makefile.am
@@ -20,6 +20,7 @@ bin_PROGRAMS = \
   taler-exchange-aggregator \
   taler-exchange-closer \
   taler-exchange-httpd \
+  taler-exchange-router \
   taler-exchange-transfer \
   taler-exchange-wirewatch
 
@@ -50,9 +51,9 @@ taler_exchange_closer_LDADD = \
   -lgnunetutil \
   $(XLIB)
 
-taler_exchange_wirewatch_SOURCES = \
-  taler-exchange-wirewatch.c
-taler_exchange_wirewatch_LDADD = \
+taler_exchange_router_SOURCES = \
+  taler-exchange-router.c
+taler_exchange_router_LDADD = \
   $(LIBGCRYPT_LIBS) \
   $(top_builddir)/src/json/libtalerjson.la \
   $(top_builddir)/src/util/libtalerutil.la \
@@ -76,6 +77,20 @@ taler_exchange_transfer_LDADD = \
   -lgnunetutil \
   $(XLIB)
 
+taler_exchange_wirewatch_SOURCES = \
+  taler-exchange-wirewatch.c
+taler_exchange_wirewatch_LDADD = \
+  $(LIBGCRYPT_LIBS) \
+  $(top_builddir)/src/json/libtalerjson.la \
+  $(top_builddir)/src/util/libtalerutil.la \
+  $(top_builddir)/src/bank-lib/libtalerbank.la \
+  $(top_builddir)/src/exchangedb/libtalerexchangedb.la \
+  -ljansson \
+  -lgnunetcurl \
+  -lgnunetutil \
+  $(XLIB)
+
+
 taler_exchange_httpd_SOURCES = \
   taler-exchange-httpd.c taler-exchange-httpd.h \
   taler-exchange-httpd_auditors.c taler-exchange-httpd_auditors.h \
diff --git a/src/exchange/exchange.conf b/src/exchange/exchange.conf
index 92de5e31c..9c68208ac 100644
--- a/src/exchange/exchange.conf
+++ b/src/exchange/exchange.conf
@@ -47,6 +47,8 @@ BASE_URL = http://localhost:8081/
 # How long should the aggregator sleep if it has nothing to do?
 AGGREGATOR_IDLE_SLEEP_INTERVAL = 60 s
 
+ROUTER_IDLE_SLEEP_INTERVAL = 60 s
+
 # How long should the transfer tool
 # sleep if it has nothing to do?
 TRANSFER_IDLE_SLEEP_INTERVAL = 60 s
@@ -66,6 +68,17 @@ CLOSER_IDLE_SLEEP_INTERVAL = 60 s
 # aggregation logic will break badly!
 AGGREGATOR_SHARD_SIZE = 2147483648
 
+# Values of 0 or above 2^31 disable sharding, which
+# is a sane default for most use-cases.
+# When changing this value, you MUST stop all
+# aggregators and manually run
+#
+# $ taler-exchange-dbinit -s
+#
+# against the exchange's database. Otherwise, the
+# aggregation logic will break badly!
+ROUTER_SHARD_SIZE = 2147483648
+
 # How long should wirewatch sleep if it has nothing to do?
 # (Set very aggressively here for the demonstrators to be
 # super fast.)
diff --git a/src/exchange/taler-exchange-router.c b/src/exchange/taler-exchange-router.c
new file mode 100644
index 000000000..8d5efff0a
--- /dev/null
+++ b/src/exchange/taler-exchange-router.c
@@ -0,0 +1,448 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2022 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero 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 Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+
+/**
+ * @file taler-exchange-router.c
+ * @brief Process that routes P2P payments. Responsible for
+ *   (1) refunding coins in unmerged purses, (2) merging purses into local reserves;
+ *   (3) aggregating remote payments into the respective wad transfers.
+ *   Execution of actual wad transfers is still to be done by taler-exchange-transfer,
+ *   and watching for incoming wad transfers is done by taler-exchange-wirewatch.
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <gnunet/gnunet_util_lib.h>
+#include <jansson.h>
+#include <pthread.h>
+#include "taler_exchangedb_lib.h"
+#include "taler_exchangedb_plugin.h"
+#include "taler_json_lib.h"
+#include "taler_bank_service.h"
+
+
+/**
+ * Work shard we are processing.
+ */
+struct Shard
+{
+
+  /**
+   * When did we start processing the shard?
+   */
+  struct GNUNET_TIME_Timestamp start_time;
+
+  /**
+   * Starting row of the shard.
+   */
+  uint32_t shard_start;
+
+  /**
+   * Inclusive end row of the shard.
+   */
+  uint32_t shard_end;
+
+  /**
+   * Number of starting points found in the shard.
+   */
+  uint64_t work_counter;
+
+};
+
+
+/**
+ * What is the smallest unit we support for wire transfers?
+ * We will need to round down to a multiple of this amount.
+ */
+static struct TALER_Amount currency_round_unit;
+
+/**
+ * What is the base URL of this exchange?  Used in the
+ * wire transfer subjects so that merchants and governments
+ * can ask for the list of aggregated deposits.
+ */
+static char *exchange_base_url;
+
+/**
+ * Set to #GNUNET_YES if this exchange does not support KYC checks
+ * and thus P2P transfers are to be made regardless of the
+ * KYC status of the target reserve.
+ */
+static int kyc_off;
+
+/**
+ * The exchange's configuration.
+ */
+static const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+/**
+ * Our database plugin.
+ */
+static struct TALER_EXCHANGEDB_Plugin *db_plugin;
+
+/**
+ * Next task to run, if any.
+ */
+static struct GNUNET_SCHEDULER_Task *task;
+
+/**
+ * How long should we sleep when idle before trying to find more work?
+ */
+static struct GNUNET_TIME_Relative router_idle_sleep_interval;
+
+/**
+ * How big are the shards we are processing? Is an inclusive offset, so every
+ * shard ranges from [X,X+shard_size) exclusive.  So a shard covers
+ * shard_size slots.  The maximum value for shard_size is INT32_MAX+1.
+ */
+static uint32_t shard_size;
+
+/**
+ * Value to return from main(). 0 on success, non-zero on errors.
+ */
+static int global_ret;
+
+/**
+ * #GNUNET_YES if we are in test mode and should exit when idle.
+ */
+static int test_mode;
+
+
+/**
+ * Select a shard to work on.
+ *
+ * @param cls NULL
+ */
+static void
+run_shard (void *cls);
+
+
+/**
+ * We're being aborted with CTRL-C (or SIGTERM). Shut down.
+ *
+ * @param cls closure
+ */
+static void
+shutdown_task (void *cls)
+{
+  (void) cls;
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Running shutdown\n");
+  if (NULL != task)
+  {
+    GNUNET_SCHEDULER_cancel (task);
+    task = NULL;
+  }
+  TALER_EXCHANGEDB_plugin_unload (db_plugin);
+  db_plugin = NULL;
+  TALER_EXCHANGEDB_unload_accounts ();
+  cfg = NULL;
+}
+
+
+/**
+ * Parse the configuration for wirewatch.
+ *
+ * @return #GNUNET_OK on success
+ */
+static enum GNUNET_GenericReturnValue
+parse_wirewatch_config (void)
+{
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_string (cfg,
+                                             "exchange",
+                                             "BASE_URL",
+                                             &exchange_base_url))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               "exchange",
+                               "BASE_URL");
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (cfg,
+                                           "exchange",
+                                           "ROUTER_IDLE_SLEEP_INTERVAL",
+                                           &router_idle_sleep_interval))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               "exchange",
+                               "ROUTER_IDLE_SLEEP_INTERVAL");
+    return GNUNET_SYSERR;
+  }
+  if ( (GNUNET_OK !=
+        TALER_config_get_amount (cfg,
+                                 "taler",
+                                 "CURRENCY_ROUND_UNIT",
+                                 &currency_round_unit)) ||
+       ( (0 != currency_round_unit.fraction) &&
+         (0 != currency_round_unit.value) ) )
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Need non-zero value in section `TALER' under `CURRENCY_ROUND_UNIT'\n");
+    return GNUNET_SYSERR;
+  }
+
+  if (NULL ==
+      (db_plugin = TALER_EXCHANGEDB_plugin_load (cfg)))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Failed to initialize DB subsystem\n");
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK !=
+      TALER_EXCHANGEDB_load_accounts (cfg,
+                                      TALER_EXCHANGEDB_ALO_DEBIT))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "No wire accounts configured for debit!\n");
+    TALER_EXCHANGEDB_plugin_unload (db_plugin);
+    db_plugin = NULL;
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Perform a database commit. If it fails, print a warning.
+ *
+ * @return status of commit
+ */
+static enum GNUNET_DB_QueryStatus
+commit_or_warn (void)
+{
+  enum GNUNET_DB_QueryStatus qs;
+
+  qs = db_plugin->commit (db_plugin->cls);
+  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
+    return qs;
+  GNUNET_log ((GNUNET_DB_STATUS_SOFT_ERROR == qs)
+              ? GNUNET_ERROR_TYPE_INFO
+              : GNUNET_ERROR_TYPE_ERROR,
+              "Failed to commit database transaction!\n");
+  return qs;
+}
+
+
+/**
+ * Release lock on shard @a s in the database.
+ * On error, terminates this process.
+ *
+ * @param[in] s shard to free (and memory to release)
+ */
+static void
+release_shard (struct Shard *s)
+{
+  enum GNUNET_DB_QueryStatus qs;
+
+  qs = db_plugin->release_revolving_shard (
+    db_plugin->cls,
+    "router",
+    s->shard_start,
+    s->shard_end);
+  GNUNET_free (s);
+  switch (qs)
+  {
+  case GNUNET_DB_STATUS_HARD_ERROR:
+  case GNUNET_DB_STATUS_SOFT_ERROR:
+    GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR != qs);
+    GNUNET_break (0);
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+    /* Strange, but let's just continue */
+    break;
+  case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+    /* normal case */
+    break;
+  }
+}
+
+
+static void
+run_routing (void *cls)
+{
+  struct Shard *s = cls;
+
+  task = NULL;
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Checking for ready P2P transfers to route\n");
+  // FIXME: do actual work here!
+  commit_or_warn ();
+  release_shard (s);
+  task = GNUNET_SCHEDULER_add_now (&run_shard,
+                                   NULL);
+}
+
+
+/**
+ * Select a shard to work on.
+ *
+ * @param cls NULL
+ */
+static void
+run_shard (void *cls)
+{
+  struct Shard *s;
+  enum GNUNET_DB_QueryStatus qs;
+
+  (void) cls;
+  task = NULL;
+  if (GNUNET_SYSERR ==
+      db_plugin->preflight (db_plugin->cls))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Failed to obtain database connection!\n");
+    global_ret = EXIT_FAILURE;
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  s = GNUNET_new (struct Shard);
+  s->start_time = GNUNET_TIME_timestamp_get ();
+  qs = db_plugin->begin_revolving_shard (db_plugin->cls,
+                                         "router",
+                                         shard_size,
+                                         1U + INT32_MAX,
+                                         &s->shard_start,
+                                         &s->shard_end);
+  if (0 >= qs)
+  {
+    if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
+    {
+      static struct GNUNET_TIME_Relative delay;
+
+      GNUNET_free (s);
+      delay = GNUNET_TIME_randomized_backoff (delay,
+                                              GNUNET_TIME_UNIT_SECONDS);
+      task = GNUNET_SCHEDULER_add_delayed (delay,
+                                           &run_shard,
+                                           NULL);
+      return;
+    }
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Failed to begin shard (%d)!\n",
+                qs);
+    GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR != qs);
+    global_ret = EXIT_FAILURE;
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Starting shard [%u:%u]!\n",
+              (unsigned int) s->shard_start,
+              (unsigned int) s->shard_end);
+  task = GNUNET_SCHEDULER_add_now (&run_routing,
+                                   s);
+}
+
+
+/**
+ * First task.
+ *
+ * @param cls closure, NULL
+ * @param args remaining command-line arguments
+ * @param cfgfile name of the configuration file used (for saving, can be NULL!)
+ * @param c configuration
+ */
+static void
+run (void *cls,
+     char *const *args,
+     const char *cfgfile,
+     const struct GNUNET_CONFIGURATION_Handle *c)
+{
+  unsigned long long ass;
+  (void) cls;
+  (void) args;
+  (void) cfgfile;
+
+  cfg = c;
+  if (GNUNET_OK != parse_wirewatch_config ())
+  {
+    cfg = NULL;
+    global_ret = EXIT_NOTCONFIGURED;
+    return;
+  }
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_number (cfg,
+                                             "exchange",
+                                             "ROUTER_SHARD_SIZE",
+                                             &ass))
+  {
+    cfg = NULL;
+    global_ret = EXIT_NOTCONFIGURED;
+    return;
+  }
+  if ( (0 == ass) ||
+       (ass > INT32_MAX) )
+    shard_size = 1U + INT32_MAX;
+  else
+    shard_size = (uint32_t) ass;
+  GNUNET_assert (NULL == task);
+  task = GNUNET_SCHEDULER_add_now (&run_shard,
+                                   NULL);
+  GNUNET_SCHEDULER_add_shutdown (&shutdown_task,
+                                 cls);
+}
+
+
+/**
+ * The main function of the taler-exchange-router.
+ *
+ * @param argc number of arguments from the command line
+ * @param argv command line arguments
+ * @return 0 ok, non-zero on error, see #global_ret
+ */
+int
+main (int argc,
+      char *const *argv)
+{
+  struct GNUNET_GETOPT_CommandLineOption options[] = {
+    GNUNET_GETOPT_option_timetravel ('T',
+                                     "timetravel"),
+    GNUNET_GETOPT_option_flag ('t',
+                               "test",
+                               "run in test mode and exit when idle",
+                               &test_mode),
+    GNUNET_GETOPT_option_flag ('y',
+                               "kyc-off",
+                               "perform wire transfers without KYC checks",
+                               &kyc_off),
+    GNUNET_GETOPT_OPTION_END
+  };
+  enum GNUNET_GenericReturnValue ret;
+
+  if (GNUNET_OK !=
+      GNUNET_STRINGS_get_utf8_args (argc, argv,
+                                    &argc, &argv))
+    return EXIT_INVALIDARGUMENT;
+  TALER_OS_init ();
+  ret = GNUNET_PROGRAM_run (
+    argc, argv,
+    "taler-exchange-router",
+    gettext_noop (
+      "background process that routes P2P transfers"),
+    options,
+    &run, NULL);
+  GNUNET_free_nz ((void *) argv);
+  if (GNUNET_SYSERR == ret)
+    return EXIT_INVALIDARGUMENT;
+  if (GNUNET_NO == ret)
+    return EXIT_SUCCESS;
+  return global_ret;
+}
+
+
+/* end of taler-exchange-router.c */