[taler-exchange] 94/130: implement /kyc-proof client API

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grothoff pushed a commit to branch master
in repository exchange.

commit 121bfe3659c988f0aab070b3ae291b7b6f13f8f7
Author: Christian Grothoff <christian@grothoff.org>
AuthorDate: Sun Nov 7 13:05:33 2021 +0100

    implement /kyc-proof client API
---
 src/include/taler_exchange_service.h |  82 +++++++++++++
 src/lib/Makefile.am                  |   1 +
 src/lib/exchange_api_kyc_proof.c     | 217 +++++++++++++++++++++++++++++++++++
 3 files changed, 300 insertions(+)

diff --git a/src/include/taler_exchange_service.h 
b/src/include/taler_exchange_service.h
index 361956cb..54fca65c 100644
--- a/src/include/taler_exchange_service.h
+++ b/src/include/taler_exchange_service.h
@@ -2160,6 +2160,88 @@ void
 TALER_EXCHANGE_kyc_check_cancel (struct TALER_EXCHANGE_KycCheckHandle *kyc);
 
 
+/**
+ * KYC proof response details.
+ */
+struct TALER_EXCHANGE_KycProofResponse
+{
+  /**
+   * HTTP status code returned by the exchange.
+   */
+  unsigned int http_status;
+
+  /**
+   * Taler error code, if any.
+   */
+  enum TALER_ErrorCode ec;
+
+  union
+  {
+
+    /**
+     * KYC is OK, affirmation returned by the exchange.
+     */
+    struct
+    {
+
+      /**
+       * Where to redirect the client next.
+       */
+      const char *redirect_url;
+
+    } found;
+
+  } details;
+
+};
+
+/**
+ * Function called with the result of a KYC check.
+ *
+ * @param cls closure
+ * @param ks the account's KYC status details
+ */
+typedef void
+(*TALER_EXCHANGE_KycProofCallback)(
+  void *cls,
+  const struct TALER_EXCHANGE_KycProofResponse *kpr);
+
+
+/**
+ * Handle for a /kyc-proof operation.
+ */
+struct TALER_EXCHANGE_KycProofHandle;
+
+
+/**
+ * Run interaction with exchange to provide proof of KYC status.
+ *
+ * @param eh exchange handle to use
+ * @param payment_target number identifying the target
+ * @param code OAuth 2.0 code argument
+ * @param state OAuth 2.0 state argument
+ * @param cb function to call with the result
+ * @param cb_cls closure for @a cb
+ * @return NULL on error
+ */
+struct TALER_EXCHANGE_KycProofHandle *
+TALER_EXCHANGE_kyc_proof (struct TALER_EXCHANGE_Handle *eh,
+                          uint64_t payment_target,
+                          const char *code,
+                          const char *state,
+                          TALER_EXCHANGE_KycProofCallback cb,
+                          void *cb_cls);
+
+
+/**
+ * Cancel KYC proof operation.
+ *
+ * @param kph handle for operation to cancel
+ */
+void
+TALER_EXCHANGE_kyc_proof_cancel (struct TALER_EXCHANGE_KycProofHandle *kph);
+
+
 /**
  * Handle for a ``/kyc-wallet`` operation.
  */
diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am
index 518b725a..2862799d 100644
--- a/src/lib/Makefile.am
+++ b/src/lib/Makefile.am
@@ -28,6 +28,7 @@ libtalerexchange_la_SOURCES = \
   exchange_api_deposit.c \
   exchange_api_deposits_get.c \
   exchange_api_kyc_check.c \
+  exchange_api_kyc_proof.c \
   exchange_api_kyc_wallet.c \
   exchange_api_link.c \
   exchange_api_management_auditor_disable.c \
diff --git a/src/lib/exchange_api_kyc_proof.c b/src/lib/exchange_api_kyc_proof.c
new file mode 100644
index 00000000..80215227
--- /dev/null
+++ b/src/lib/exchange_api_kyc_proof.c
@@ -0,0 +1,217 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2021 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_kyc_proof.c
+ * @brief Implementation of the /kyc-proof request
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <microhttpd.h> /* just for HTTP proof codes */
+#include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
+#include "taler_exchange_service.h"
+#include "taler_json_lib.h"
+#include "exchange_api_handle.h"
+#include "taler_signatures.h"
+#include "exchange_api_curl_defaults.h"
+
+
+/**
+ * @brief A ``/kyc-proof`` handle
+ */
+struct TALER_EXCHANGE_KycProofHandle
+{
+
+  /**
+   * The connection to exchange this request handle will use
+   */
+  struct TALER_EXCHANGE_Handle *exchange;
+
+  /**
+   * The url for this request.
+   */
+  char *url;
+
+  /**
+   * Handle to our CURL request.
+   */
+  CURL *eh;
+
+  /**
+   * Handle for the request.
+   */
+  struct GNUNET_CURL_Job *job;
+
+  /**
+   * Function to call with the result.
+   */
+  TALER_EXCHANGE_KycProofCallback cb;
+
+  /**
+   * Closure for @e cb.
+   */
+  void *cb_cls;
+
+};
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /kyc-proof request.
+ *
+ * @param cls the `struct TALER_EXCHANGE_KycProofHandle`
+ * @param response_code HTTP response code, 0 on error
+ * @param response parsed JSON result, NULL on error
+ */
+static void
+handle_kyc_proof_finished (void *cls,
+                           long response_code,
+                           const void *response)
+{
+  struct TALER_EXCHANGE_KycProofHandle *kph = cls;
+  const json_t *j = response;
+  struct TALER_EXCHANGE_KycProofResponse kpr = {
+    .http_status = (unsigned int) response_code
+  };
+
+  kph->job = NULL;
+  switch (response_code)
+  {
+  case 0:
+    kpr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
+    break;
+  case MHD_HTTP_FOUND:
+    {
+      char *redirect_url;
+
+      GNUNET_assert (CURLE_OK ==
+                     curl_easy_getinfo (kph->eh,
+                                        CURLINFO_REDIRECT_URL,
+                                        &redirect_url));
+      kpr.details.found.redirect_url = redirect_url;
+      break;
+    }
+  case MHD_HTTP_BAD_REQUEST:
+    kpr.ec = TALER_JSON_get_error_code (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_UNAUTHORIZED:
+    kpr.ec = TALER_JSON_get_error_code (j);
+    break;
+  case MHD_HTTP_NOT_FOUND:
+    kpr.ec = TALER_JSON_get_error_code (j);
+    break;
+  case MHD_HTTP_BAD_GATEWAY:
+    kpr.ec = TALER_JSON_get_error_code (j);
+    /* Server had an internal issue; we should retry, but this API
+       leaves this to the application */
+    break;
+  case MHD_HTTP_GATEWAY_TIMEOUT:
+    kpr.ec = TALER_JSON_get_error_code (j);
+    /* Server had an internal issue; we should retry, but this API
+       leaves this to the application */
+    break;
+  default:
+    /* unexpected response code */
+    GNUNET_break_op (0);
+    kpr.ec = TALER_JSON_get_error_code (j);
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u/%d for exchange kyc_proof\n",
+                (unsigned int) response_code,
+                (int) kpr.ec);
+    break;
+  }
+  kph->cb (kph->cb_cls,
+           &kpr);
+  TALER_EXCHANGE_kyc_proof_cancel (kph);
+}
+
+
+struct TALER_EXCHANGE_KycProofHandle *
+TALER_EXCHANGE_kyc_proof (struct TALER_EXCHANGE_Handle *exchange,
+                          uint64_t payment_target,
+                          const char *code,
+                          const char *state,
+                          TALER_EXCHANGE_KycProofCallback cb,
+                          void *cb_cls)
+{
+  struct TALER_EXCHANGE_KycProofHandle *kph;
+  struct GNUNET_CURL_Context *ctx;
+  char *arg_str;
+
+  if (GNUNET_YES !=
+      TEAH_handle_is_ready (exchange))
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  /* TODO: any escaping of code/state needed??? */
+  GNUNET_asprintf (&arg_str,
+                   "/kyc-proof/%llu?code=%s&state=%s",
+                   (unsigned long long) payment_target,
+                   code,
+                   state);
+  kph = GNUNET_new (struct TALER_EXCHANGE_KycProofHandle);
+  kph->exchange = exchange;
+  kph->cb = cb;
+  kph->cb_cls = cb_cls;
+  kph->url = TEAH_path_to_url (exchange,
+                               arg_str);
+  GNUNET_free (arg_str);
+  if (NULL == kph->url)
+  {
+    GNUNET_free (kph);
+    return NULL;
+  }
+  kph->eh = TALER_EXCHANGE_curl_easy_get_ (kph->url);
+  if (NULL == kph->eh)
+  {
+    GNUNET_break (0);
+    GNUNET_free (kph->url);
+    GNUNET_free (kph);
+    return NULL;
+  }
+  /* disable location following, we want to learn the
+     result of a 302 redirect! */
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (kph->eh,
+                                   CURLOPT_FOLLOWLOCATION,
+                                   0L));
+  ctx = TEAH_handle_to_context (exchange);
+  kph->job = GNUNET_CURL_job_add_with_ct_json (ctx,
+                                               kph->eh,
+                                               &handle_kyc_proof_finished,
+                                               kph);
+  return kph;
+}
+
+
+void
+TALER_EXCHANGE_kyc_proof_cancel (struct TALER_EXCHANGE_KycProofHandle *kph)
+{
+  if (NULL != kph->job)
+  {
+    GNUNET_CURL_job_cancel (kph->job);
+    kph->job = NULL;
+  }
+  GNUNET_free (kph->url);
+  GNUNET_free (kph);
+}
+
+
+/* end of exchange_api_kyc_proof.c */

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