-skeleton for GET /contracts/ logic

src/include/taler_exchange_service.h

@@ -4061,12 +4061,12 @@ struct TALER_EXCHANGE_ContractGetResponse
  * Function called with information about the a purse.
  *
  * @param cls closure
- * @param pgr HTTP response data
+ * @param cgr HTTP response data
  */
 typedef void
 (*TALER_EXCHANGE_ContractGetCallback) (
   void *cls,
-  const struct TALER_EXCHANGE_ContractGetResponse *pgr);
+  const struct TALER_EXCHANGE_ContractGetResponse *cgr);
 
 
 /**
@@ -4078,8 +4078,7 @@ struct TALER_EXCHANGE_ContractsGetHandle;
 /**
  * Request information about a contract from the exchange.
  *
- * @param ctx the context
+ * @param exchange exchange handle
- * @param url HTTP base URL for the exchange
  * @param contract_priv private key of the contract
  * @param cb function to call with the exchange's result
  * @param cb_cls closure for @a cb
@@ -4087,8 +4086,7 @@ struct TALER_EXCHANGE_ContractsGetHandle;
  */
 struct TALER_EXCHANGE_ContractGetHandle *
 TALER_EXCHANGE_contract_get (
-  struct GNUNET_CURL_Context *ctx,
+  struct TALER_EXCHANGE_Handle *exchange,
-  const char *url,
   const struct TALER_ContractDiffiePrivateP *contract_priv,
   TALER_EXCHANGE_ContractGetCallback cb,
   void *cb_cls);
@@ -4165,8 +4163,7 @@ struct TALER_EXCHANGE_PurseGetHandle;
 /**
  * Request information about a purse from the exchange.
  *
- * @param ctx the context
+ * @param exchange exchange handle
- * @param url HTTP base URL for the exchange
  * @param purse_priv private key of the purse
  * @param merge_timeout how long to wait for a merge to happen
  * @param deposit_timeout how long to wait for a deposit to happen
@@ -4176,8 +4173,7 @@ struct TALER_EXCHANGE_PurseGetHandle;
  */
 struct TALER_EXCHANGE_PurseGetHandle *
 TALER_EXCHANGE_purse_get (
-  struct GNUNET_CURL_Context *ctx,
+  struct TALER_EXCHANGE_Handle *exchange,
-  const char *url,
   const struct TALER_PurseContractPrivateKeyP *purse_priv,
   struct GNUNET_TIME_Relative merge_timeout,
   struct GNUNET_TIME_Relative deposit_timeout,

src/lib/exchange_api_contracts_get.c

@@ -0,0 +1,255 @@
+/*
+  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 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 lib/exchange_api_contracts_get.c
+ * @brief Implementation of the /contracts/ GET request
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <jansson.h>
+#include <microhttpd.h> /* just for HTTP status codes */
+#include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
+#include "taler_json_lib.h"
+#include "taler_exchange_service.h"
+#include "exchange_api_handle.h"
+#include "taler_signatures.h"
+#include "exchange_api_curl_defaults.h"
+
+
+/**
+ * @brief A Contract Get Handle
+ */
+struct TALER_EXCHANGE_ContractsGetHandle
+{
+
+  /**
+   * The connection to exchange this request handle will use
+   */
+  struct TALER_EXCHANGE_Handle *exchange;
+
+  /**
+   * The url for this request.
+   */
+  char *url;
+
+  /**
+   * Handle for the request.
+   */
+  struct GNUNET_CURL_Job *job;
+
+  /**
+   * Function to call with the result.
+   */
+  TALER_EXCHANGE_ContractGetCallback cb;
+
+  /**
+   * Closure for @a cb.
+   */
+  void *cb_cls;
+
+  /**
+   * Private key needed to decrypt the contract.
+   */
+  struct TALER_ContractDiffiePrivateP contract_priv;
+
+};
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /track/transaction request.
+ *
+ * @param cls the `struct TALER_EXCHANGE_ContractsGetHandle`
+ * @param response_code HTTP response code, 0 on error
+ * @param response parsed JSON result, NULL on error
+ */
+static void
+handle_contract_get_finished (void *cls,
+                              long response_code,
+                              const void *response)
+{
+  struct TALER_EXCHANGE_ContractsGetHandle *cgh = cls;
+  const json_t *j = response;
+  struct TALER_EXCHANGE_ContractGetResponse dr = {
+    .hr.reply = j,
+    .hr.http_status = (unsigned int) response_code
+  };
+
+  cgh->job = NULL;
+  switch (response_code)
+  {
+  case 0:
+    dr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
+    break;
+  case MHD_HTTP_OK:
+    {
+      void *econtract;
+      size_t econtract_size;
+      struct TALER_PurseContractPublicKeyP purse_pub;
+      struct TALER_PurseContractSignatureP econtract_sig;
+      struct GNUNET_JSON_Specification spec[] = {
+        GNUNET_JSON_spec_fixed_auto ("purse_pub",
+                                     &purse_pub),
+        GNUNET_JSON_spec_fixed_auto ("econtract_sig",
+                                     &econtract_sig),
+        GNUNET_JSON_spec_varsize ("econtract",
+                                  &econtract,
+                                  &econtract_size),
+        GNUNET_JSON_spec_end ()
+      };
+
+      if (GNUNET_OK !=
+          GNUNET_JSON_parse (j,
+                             spec,
+                             NULL, NULL))
+      {
+        GNUNET_break_op (0);
+        dr.hr.http_status = 0;
+        dr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+        break;
+      }
+      // FIXME: verify econtract_sig!
+      // FIXME: decrypt, build up 'dr'!
+      cgh->cb (cgh->cb_cls,
+               &dr);
+      GNUNET_JSON_parse_free (spec);
+      TALER_EXCHANGE_contracts_get_cancel (cgh);
+      return;
+    }
+  case MHD_HTTP_BAD_REQUEST:
+    dr.hr.ec = TALER_JSON_get_error_code (j);
+    dr.hr.hint = TALER_JSON_get_error_hint (j);
+    /* This should never happen, either us or the exchange is buggy
+       (or API version conflict); just pass JSON reply to the application */
+    break;
+  case MHD_HTTP_FORBIDDEN:
+    dr.hr.ec = TALER_JSON_get_error_code (j);
+    dr.hr.hint = TALER_JSON_get_error_hint (j);
+    /* Nothing really to verify, exchange says one of the signatures is
+       invalid; as we checked them, this should never happen, we
+       should pass the JSON reply to the application */
+    break;
+  case MHD_HTTP_NOT_FOUND:
+    dr.hr.ec = TALER_JSON_get_error_code (j);
+    dr.hr.hint = TALER_JSON_get_error_hint (j);
+    /* Exchange does not know about transaction;
+       we should pass the reply to the application */
+    break;
+  case MHD_HTTP_INTERNAL_SERVER_ERROR:
+    dr.hr.ec = TALER_JSON_get_error_code (j);
+    dr.hr.hint = TALER_JSON_get_error_hint (j);
+    /* Server had an internal issue; we should retry, but this API
+       leaves this to the application */
+    break;
+  default:
+    /* unexpected response code */
+    dr.hr.ec = TALER_JSON_get_error_code (j);
+    dr.hr.hint = TALER_JSON_get_error_hint (j);
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u/%d for exchange GET contracts\n",
+                (unsigned int) response_code,
+                (int) dr.hr.ec);
+    GNUNET_break_op (0);
+    break;
+  }
+  cgh->cb (cgh->cb_cls,
+           &dr);
+  TALER_EXCHANGE_contracts_get_cancel (cgh);
+}
+
+
+struct TALER_EXCHANGE_ContractGetHandle *
+TALER_EXCHANGE_contract_get (
+  struct TALER_EXCHANGE_Handle *exchange,
+  const struct TALER_ContractDiffiePrivateP *contract_priv,
+  TALER_EXCHANGE_ContractGetCallback cb,
+  void *cb_cls)
+{
+  struct TALER_EXCHANGE_ContractsGetHandle *cgh;
+  CURL *eh;
+  struct TALER_ContractDiffiePublicP cpub;
+  char arg_str[sizeof (cpub) * 2 + 48];
+
+  if (GNUNET_YES !=
+      TEAH_handle_is_ready (exchange))
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  GNUNET_CRYPTO_ecdhe_key_get_public (&contract_priv->ecdhe_priv,
+                                      &cpub.ecdhe_pub);
+  {
+    char cpub_str[sizeof (cpub) * 2];
+    char *end;
+
+    end = GNUNET_STRINGS_data_to_string (&cpub,
+                                         sizeof (cpub),
+                                         cpub_str,
+                                         sizeof (cpub_str));
+    *end = '\0';
+    GNUNET_snprintf (arg_str,
+                     sizeof (arg_str),
+                     "/contracts/%s",
+                     cpub_str);
+  }
+
+  cgh = GNUNET_new (struct TALER_EXCHANGE_ContractsGetHandle);
+  cgh->exchange = exchange;
+  cgh->cb = cb;
+  cgh->cb_cls = cb_cls;
+  cgh->url = TEAH_path_to_url (exchange,
+                               arg_str);
+  if (NULL == cgh->url)
+  {
+    GNUNET_free (cgh);
+    return NULL;
+  }
+  cgh->contract_priv = *contract_priv;
+
+  eh = TALER_EXCHANGE_curl_easy_get_ (cgh->url);
+  if (NULL == eh)
+  {
+    GNUNET_break (0);
+    GNUNET_free (cgh->url);
+    GNUNET_free (cgh);
+    return NULL;
+  }
+  cgh->job = GNUNET_CURL_job_add (TEAH_handle_to_context (exchange),
+                                  eh,
+                                  &handle_contract_get_finished,
+                                  cgh);
+  return cgh;
+}
+
+
+void
+TALER_EXCHANGE_contracts_get_cancel (struct
+                                     TALER_EXCHANGE_ContractsGetHandle *cgh)
+{
+  if (NULL != cgh->job)
+  {
+    GNUNET_CURL_job_cancel (cgh->job);
+    cgh->job = NULL;
+  }
+  GNUNET_free (cgh->url);
+  GNUNET_free (cgh);
+}
+
+
+/* end of exchange_api_contracts_get.c */