implement TALER_MERCHANT_tip_authorize

1 files changed, 267 insertions, 0 deletions

diff --git a/src/lib/merchant_api_tip_authorize.c b/src/lib/merchant_api_tip_authorize.c
new file mode 100644
index 00000000..eb3e657e
--- /dev/null
+++ b/src/lib/merchant_api_tip_authorize.c
@@ -0,0 +1,267 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014-2017 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Lesser General Public License as published by the Free Software
+  Foundation; either version 2.1, 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 Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License along with
+  TALER; see the file COPYING.LGPL.  If not, see
+  <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file lib/merchant_api_tip_authorize.c
+ * @brief Implementation of the /tip-authorize request of the merchant's HTTP API
+ * @author Marcello Stanisci
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <curl/curl.h>
+#include <jansson.h>
+#include <microhttpd.h> /* just for HTTP status codes */
+#include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
+#include "taler_merchant_service.h"
+#include <taler/taler_json_lib.h>
+#include <taler/taler_signatures.h>
+#include "merchant_api_common.h"
+
+
+/**
+ * @brief A handle for tracking transactions.
+ */
+struct TALER_MERCHANT_TipAuthorizeOperation
+{
+
+  /**
+   * The url for this request.
+   */
+  char *url;
+
+  /**
+   * JSON encoding of the request to POST.
+   */
+  char *json_enc;
+
+  /**
+   * Handle for the request.
+   */
+  struct GNUNET_CURL_Job *job;
+
+  /**
+   * Function to call with the result.
+   */
+  TALER_MERCHANT_TipAuthorizeCallback cb;
+
+  /**
+   * Closure for @a cb.
+   */
+  void *cb_cls;
+
+  /**
+   * Reference to the execution context.
+   */
+  struct GNUNET_CURL_Context *ctx;
+};
+
+
+/**
+ * We got a 200 response back from the exchange (or the merchant).
+ * Now we need to parse the response and if it is well-formed,
+ * call the callback (and set it to NULL afterwards).
+ *
+ * @param tao handle of the original authorization operation
+ * @param json cryptographic proof returned by the exchange/merchant
+ * @return #GNUNET_OK if response is valid
+ */
+static int
+check_ok (struct TALER_MERCHANT_TipAuthorizeOperation *tao,
+          const json_t *json)
+{
+  struct GNUNET_HashCode tip_id;
+  struct GNUNET_TIME_Absolute tip_expiration;
+  const char *exchange_uri;
+  struct GNUNET_JSON_Specification spec[] = {
+    GNUNET_JSON_spec_absolute_time ("expiration", &tip_expiration),
+    GNUNET_JSON_spec_fixed_auto ("tip_id", &tip_id),
+    GNUNET_JSON_spec_string ("exchange_uri", &exchange_uri),
+    GNUNET_JSON_spec_end()
+  };
+
+  if (GNUNET_OK !=
+      GNUNET_JSON_parse (json,
+                         spec,
+                         NULL, NULL))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+  tao->cb (tao->cb_cls,
+           MHD_HTTP_OK,
+           TALER_JSON_get_error_code (json),
+           &tip_id,
+           tip_expiration,
+           exchange_uri);
+  tao->cb = NULL; /* do not call twice */
+  GNUNET_JSON_parse_free (spec);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /track/transaction request.
+ *
+ * @param cls the `struct TALER_MERCHANT_TipAuthorizeOperation`
+ * @param response_code HTTP response code, 0 on error
+ * @param json response body, NULL if not in JSON
+ */
+static void
+handle_tip_authorize_finished (void *cls,
+                               long response_code,
+                               const json_t *json)
+{
+  struct TALER_MERCHANT_TipAuthorizeOperation *tao = cls;
+
+  tao->job = NULL;
+  switch (response_code)
+  {
+  case MHD_HTTP_OK:
+    if (GNUNET_OK != check_ok (tao,
+                              json))
+    {
+      GNUNET_break_op (0);
+      response_code = 0;
+    }
+    break;
+  case MHD_HTTP_INTERNAL_SERVER_ERROR:
+    /* Server had an internal issue; we should retry, but this API
+       leaves this to the application */
+    break;
+  default:
+    /* unexpected response code */
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u\n",
+                (unsigned int) response_code);
+    GNUNET_break (0);
+    response_code = 0;
+    break;
+  }
+  if (NULL != tao->cb)
+    tao->cb (tao->cb_cls,
+             response_code,
+             TALER_JSON_get_error_code (json),
+             NULL,
+             GNUNET_TIME_UNIT_ZERO_ABS,
+             NULL);
+  TALER_MERCHANT_tip_authorize_cancel (tao);
+}
+
+
+/**
+ * Issue a /tip-authorize request to the backend.  Informs the backend
+ * that a tip should be created.
+ *
+ * @param ctx execution context
+ * @param backend_uri base URL of the merchant backend
+ * @param amount amount to be handed out as a tip
+ * @param instance which backend instance should create the tip (identifies the reserve and exchange)
+ * @param justification which justification should be stored (human-readable reason for the tip)
+ * @param authorize_cb callback which will work the response gotten from the backend
+ * @param authorize_cb_cls closure to pass to @a authorize_cb
+ * @return handle for this operation, NULL upon errors
+ */
+struct TALER_MERCHANT_TipAuthorizeOperation *
+TALER_MERCHANT_tip_authorize (struct GNUNET_CURL_Context *ctx,
+                              const char *backend_uri,
+                              const struct TALER_Amount *amount,
+                              const char *instance,
+                              const char *justification,
+                              TALER_MERCHANT_TipAuthorizeCallback authorize_cb,
+                              void *authorize_cb_cls)
+{
+  struct TALER_MERCHANT_TipAuthorizeOperation *tao;
+  CURL *eh;
+  json_t *te_obj;
+
+  tao = GNUNET_new (struct TALER_MERCHANT_TipAuthorizeOperation);
+  tao->ctx = ctx;
+  tao->cb = authorize_cb;
+  tao->cb_cls = authorize_cb_cls;
+  tao->url = MAH_path_to_url_ (backend_uri,
+                               "/tip-authorize");
+  te_obj = json_pack ("{"
+                      " s:o," /* amount */
+                      " s:s," /* instance */
+                      " s:s," /* justification */
+                      "}",
+                      "amount", TALER_JSON_from_amount (amount),
+                      "instance", instance,
+                      "justification", justification);
+  if (NULL == te_obj)
+  {
+    GNUNET_break (0);
+    GNUNET_free (tao->url);
+    return NULL;
+  }
+  if (NULL == (tao->json_enc =
+               json_dumps (te_obj,
+                           JSON_COMPACT)))
+  {
+    GNUNET_break (0);
+    json_decref (te_obj);
+    GNUNET_free (tao->url);
+    GNUNET_free (tao);
+    return NULL;
+  }
+  json_decref (te_obj);
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Requesting URI '%s'\n",
+              tao->url);
+  eh = curl_easy_init ();
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_URL,
+                                   tao->url));
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_POSTFIELDS,
+                                   tao->json_enc));
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_POSTFIELDSIZE,
+                                   strlen (tao->json_enc)));
+  tao->job = GNUNET_CURL_job_add (ctx,
+                                  eh,
+                                  GNUNET_YES,
+                                  &handle_tip_authorize_finished,
+                                  tao);
+  return tao;
+}
+
+
+/**
+ * Cancel a /track/transaction request.  This function cannot be used
+ * on a request handle if a response is already served for it.
+ *
+ * @param tao handle to the tracking operation being cancelled
+ */
+void
+TALER_MERCHANT_tip_authorize_cancel (struct TALER_MERCHANT_TipAuthorizeOperation *tao)
+{
+  if (NULL != tao->job)
+  {
+    GNUNET_CURL_job_cancel (tao->job);
+    tao->job = NULL;
+  }
+  GNUNET_free_non_null (tao->json_enc);
+  GNUNET_free (tao->url);
+  GNUNET_free (tao);
+}
+
+/* end of merchant_api_tip_authorize.c */