start skeleton for taler-exchange-offline tool

src/exchange-tools/.gitignore

@@ -1,3 +1,4 @@
 test_taler_exchange_httpd_home/.local/share/taler/exchange/live-keys/
 test_taler_exchange_httpd_home/.local/share/taler/exchange/wirefees/
 test_taler_exchange_httpd_home/.config/taler/account-1.json
+taler-exchange-offline

src/exchange-tools/Makefile.am

@@ -15,6 +15,7 @@ endif
 bin_PROGRAMS = \
   taler-exchange-keyup \
   taler-exchange-keycheck \
+  taler-exchange-offline \
   taler-exchange-wire \
   taler-exchange-dbinit
 
@@ -32,6 +33,18 @@ taler_exchange_keyup_LDADD = \
 taler_exchange_keyup_LDFLAGS = $(POSTGRESQL_LDFLAGS)
 
 
+taler_exchange_offline_SOURCES = \
+  taler-exchange-offline.c
+taler_exchange_offline_LDADD = \
+  $(LIBGCRYPT_LIBS) \
+  $(top_builddir)/src/lib/libtalerexchange.la \
+  $(top_builddir)/src/json/libtalerjson.la \
+  $(top_builddir)/src/util/libtalerutil.la \
+  -lgnunetcurl \
+  -lgnunetutil \
+  $(XLIB)
+
+
 taler_exchange_wire_SOURCES = \
   taler-exchange-wire.c
 taler_exchange_wire_LDADD = \

src/exchange-tools/taler-exchange-offline.c

@@ -0,0 +1,300 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2020 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 taler-exchange-offline.c
+ * @brief Support for operations involving the exchange's offline master key.
+ * @author Christian Grothoff
+ */
+#include <platform.h>
+#include "taler_exchange_service.h"
+
+
+/**
+ * Our context for making HTTP requests.
+ */
+static struct GNUNET_CURL_Context *ctx;
+
+/**
+ * Reschedule context for #ctx.
+ */
+static struct GNUNET_CURL_RescheduleContext *rc;
+
+/**
+ * Handle to the exchange's configuration
+ */
+static const struct GNUNET_CONFIGURATION_Handle *kcfg;
+
+/**
+ * Return value from main().
+ */
+static int global_ret;
+
+
+/**
+ * A subcommand supported by this program.
+ */
+struct SubCommand
+{
+  /**
+   * Name of the command.
+   */
+  const char *name;
+
+  /**
+   * Help text for the command.
+   */
+  const char *help;
+
+  /**
+   * Function implementing the command.
+   *
+   * @param args subsequent command line arguments (char **)
+   */
+  void (*cb)(char *const *args);
+};
+
+
+/**
+ * Next work item to perform.
+ */
+static struct GNUNET_SCHEDULER_Task *nxt;
+
+/**
+ * Handle for #do_download.
+ */
+static struct TALER_EXCHANGE_ManagementGetKeysHandle *mgkh;
+
+
+/**
+ * Shutdown task. Invoked when the application is being terminated.
+ *
+ * @param cls NULL
+ */
+static void
+do_shutdown (void *cls)
+{
+  (void) cls;
+  if (NULL != nxt)
+  {
+    GNUNET_SCHEDULER_cancel (nxt);
+    nxt = NULL;
+  }
+  if (NULL != mgkh)
+  {
+    TALER_EXCHANGE_get_management_keys_cancel (mgkh);
+    mgkh = NULL;
+  }
+  if (NULL != ctx)
+  {
+    GNUNET_CURL_fini (ctx);
+    ctx = NULL;
+  }
+  if (NULL != rc)
+  {
+    GNUNET_CURL_gnunet_rc_destroy (rc);
+    rc = NULL;
+  }
+}
+
+
+/**
+ * Function to continue processing the next command.
+ *
+ * @param cls must be a `char *const*` with the array of
+ *        command-line arguments to process next
+ */
+static void
+work (void *cls);
+
+
+/**
+ * Function to schedule job to process the next command.
+ *
+ * @param args the array of command-line arguments to process next
+ */
+static void
+next (char *const *args)
+{
+  GNUNET_assert (NULL == nxt);
+  nxt = GNUNET_SCHEDULER_add_now (&work,
+                                  (void *) args);
+}
+
+
+/**
+ * Function called with information about future keys.  Dumps the JSON output
+ * (on success), either into an internal buffer or to stdout (depending on
+ * whether there are subsequent commands).
+ *
+ * @param cls closure with the `char **` remaining args
+ * @param hr HTTP response data
+ * @param keys information about the various keys used
+ *        by the exchange, NULL if /management/keys failed
+ */
+static void
+download_cb (void *cls,
+             const struct TALER_EXCHANGE_HttpResponse *hr,
+             const struct TALER_EXCHANGE_FutureKeys *keys)
+{
+  char *const *args = cls;
+
+  mgkh = NULL;
+  fprintf (stderr,
+           "FIXME: dump!\n");
+  next (args);
+}
+
+
+/**
+ * Download future keys.
+ *
+ * @param args the array of command-line arguments to process next
+ */
+static void
+do_download (char *const *args)
+{
+  char *exchange_url;
+
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_string (kcfg,
+                                             "exchange",
+                                             "BASE_URL",
+                                             &exchange_url))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               "exchange",
+                               "BASE_URL");
+    GNUNET_SCHEDULER_shutdown ();
+    return;
+  }
+  mgkh = TALER_EXCHANGE_get_management_keys (ctx,
+                                             exchange_url,
+                                             &download_cb,
+                                             (void *) args);
+  GNUNET_free (exchange_url);
+}
+
+
+static void
+work (void *cls)
+{
+  char *const *args = cls;
+  struct SubCommand cmds[] = {
+    {
+      .name = "download",
+      .help =
+        "obtain future public keys from exchange (to be performed online!)",
+      .cb = &do_download
+    },
+    /* list terminator */
+    {
+      .name = NULL,
+    }
+  };
+  (void) cls;
+
+  nxt = NULL;
+  for (unsigned int i = 0; NULL != cmds[i].name; i++)
+  {
+    if (0 == strcasecmp (cmds[i].name,
+                         args[0]))
+    {
+      cmds[i].cb (&args[1]);
+      return;
+    }
+  }
+
+  if (0 != strcasecmp ("help",
+                       args[0]))
+    fprintf (stderr,
+             "Unexpected command `%s'\n",
+             args[0]);
+  fprintf (stderr,
+           "Supported subcommands:");
+  for (unsigned int i = 0; NULL != cmds[i].name; i++)
+  {
+    fprintf (stderr,
+             "%s - %s\n",
+             cmds[i].name,
+             cmds[i].help);
+  }
+}
+
+
+/**
+ * Main function that will be run.
+ *
+ * @param cls closure
+ * @param args remaining command-line arguments
+ * @param cfgfile name of the configuration file used (for saving, can be NULL!)
+ * @param cfg configuration
+ */
+static void
+run (void *cls,
+     char *const *args,
+     const char *cfgfile,
+     const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+  kcfg = cfg;
+  ctx = GNUNET_CURL_init (&GNUNET_CURL_gnunet_scheduler_reschedule,
+                          &rc);
+  rc = GNUNET_CURL_gnunet_rc_create (ctx);
+  GNUNET_SCHEDULER_add_shutdown (&do_shutdown,
+                                 NULL);
+  next (args);
+}
+
+
+/**
+ * The main function of the taler-exchange-keyup tool.  This tool is used to
+ * create the signing and denomination keys for the exchange.  It uses the
+ * long-term offline private key and writes the (additional) key files to the
+ * respective exchange directory (from where they can then be copied to the
+ * online server).  Note that we need (at least) the most recent generated
+ * previous keys to align the validity periods.
+ *
+ * @param argc number of arguments from the command line
+ * @param argv command line arguments
+ * @return 0 ok, 1 on error
+ */
+int
+main (int argc,
+      char *const *argv)
+{
+  struct GNUNET_GETOPT_CommandLineOption options[] = {
+    GNUNET_GETOPT_OPTION_END
+  };
+
+  /* force linker to link against libtalerutil; if we do
+     not do this, the linker may "optimize" libtalerutil
+     away and skip #TALER_OS_init(), which we do need */
+  (void) TALER_project_data_default ();
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_log_setup ("taler-exchange-offline",
+                                   "WARNING",
+                                   NULL));
+  if (GNUNET_OK !=
+      GNUNET_PROGRAM_run (argc, argv,
+                          "taler-exchange-offline",
+                          "Operations for offline signing for a Taler exchange",
+                          options,
+                          &run, NULL))
+    return 1;
+  return global_ret;
+}
+
+
+/* end of taler-exchange-offline.c */