skeleton for /track/transfer and /track/transaction, renaming to match latest exchange API

1 files changed, 521 insertions, 0 deletions

diff --git a/src/backend/taler-merchant-httpd_track-transfer.c b/src/backend/taler-merchant-httpd_track-transfer.c
new file mode 100644
index 00000000..034cc5ae
--- /dev/null
+++ b/src/backend/taler-merchant-httpd_track-transfer.c
@@ -0,0 +1,521 @@
+/*
+  This file is part of TALER
+  (C) 2014, 2015, 2016 INRIA
+
+  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 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, If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file backend/taler-merchant-httpd_track-transfer.c
+ * @brief implement API for tracking transfers and wire transfers
+ * @author Marcello Stanisci
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <jansson.h>
+#include <taler/taler_signatures.h>
+#include <taler/taler_json_lib.h>
+#include "taler-merchant-httpd.h"
+#include "taler-merchant-httpd_mhd.h"
+#include "taler-merchant-httpd_parsing.h"
+#include "taler-merchant-httpd_auditors.h"
+#include "taler-merchant-httpd_exchanges.h"
+#include "taler-merchant-httpd_responses.h"
+#include "taler-merchant-httpd_track-transfer.h"
+
+
+/**
+ * How long to wait before giving up processing with the exchange?
+ */
+#define TRACK_TIMEOUT (GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 30))
+
+
+/**
+ * Context used for handing /track/transfer requests.
+ */
+struct TransferTrackContext
+{
+
+  /**
+   * This MUST be first!
+   */
+  struct TM_HandlerContext hc;
+
+  /**
+   * Handle to the exchange.
+   */
+  struct TALER_EXCHANGE_Handle *eh;
+
+  /**
+   * Handle for the /wire/transfers request.
+   */
+  struct TALER_EXCHANGE_TrackTransferHandle *wdh;
+
+  /**
+   * HTTP connection we are handling.
+   */
+  struct MHD_Connection *connection;
+
+  /**
+   * Response to return upon resume.
+   */
+  struct MHD_Response *response;
+
+  /**
+   * Handle for operation to lookup /keys (and auditors) from
+   * the exchange used for this transaction; NULL if no operation is
+   * pending.
+   */
+  struct TMH_EXCHANGES_FindOperation *fo;
+
+  /**
+   * Task run on timeout.
+   */
+  struct GNUNET_SCHEDULER_Task *timeout_task;
+
+  /**
+   * URI of the exchange.
+   */
+  char *uri;
+
+  /**
+   * Pointer to the detail that we are currently
+   * checking in #check_transfer().
+   */
+  const struct TALER_TrackTransferDetails *current_detail;
+
+  /**
+   * Argument for the /wire/transfers request.
+   */
+  struct TALER_WireTransferIdentifierRawP wtid;
+
+  /**
+   * Response code to return.
+   */
+  unsigned int response_code;
+
+  /**
+   * #GNUNET_NO if we did not find a matching coin.
+   * #GNUNET_SYSERR if we found a matching coin, but the amounts do not match.
+   * #GNUNET_OK if we did find a matching coin.
+   */
+  int check_transfer_result;
+};
+
+
+/**
+ * Free the @a rctx.
+ *
+ * @param rctx data to free
+ */
+static void
+free_transfer_track_context (struct TransferTrackContext *rctx)
+{
+  if (NULL != rctx->fo)
+  {
+    TMH_EXCHANGES_find_exchange_cancel (rctx->fo);
+    rctx->fo = NULL;
+  }
+  if (NULL != rctx->timeout_task)
+  {
+    GNUNET_SCHEDULER_cancel (rctx->timeout_task);
+    rctx->timeout_task = NULL;
+  }
+  if (NULL != rctx->wdh)
+  {
+    TALER_EXCHANGE_track_transfer_cancel (rctx->wdh);
+    rctx->wdh = NULL;
+  }
+  if (NULL != rctx->uri)
+  {
+    GNUNET_free (rctx->uri);
+    rctx->uri = NULL;
+  }
+  GNUNET_free (rctx);
+}
+
+
+/**
+ * Resume the given /track/transfer operation and send the given response.
+ * Stores the response in the @a rctx and signals MHD to resume
+ * the connection.  Also ensures MHD runs immediately.
+ *
+ * @param rctx transfer tracking context
+ * @param response_code response code to use
+ * @param response response data to send back
+ */
+static void
+resume_track_transfer_with_response (struct TransferTrackContext *rctx,
+                                     unsigned int response_code,
+                                     struct MHD_Response *response)
+{
+  rctx->response_code = response_code;
+  rctx->response = response;
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Resuming /track/transaction handling as exchange interaction is done (%u)\n",
+              response_code);
+  if (NULL != rctx->timeout_task)
+  {
+    GNUNET_SCHEDULER_cancel (rctx->timeout_task);
+    rctx->timeout_task = NULL;
+  }
+  MHD_resume_connection (rctx->connection);
+  TMH_trigger_daemon (); /* we resumed, kick MHD */
+}
+
+
+/**
+ * Custom cleanup routine for a `struct TransferTrackContext`.
+ *
+ * @param hc the `struct TransferTrackContext` to clean up.
+ */
+static void
+track_transfer_cleanup (struct TM_HandlerContext *hc)
+{
+  struct TransferTrackContext *rctx = (struct TransferTrackContext *) hc;
+
+  free_transfer_track_context (rctx);
+}
+
+
+/**
+ * Function called with information about a coin that was transfered.
+ * Verify that it matches the information claimed by the exchange.
+ * Update the `check_transfer_result` field accordingly.
+ *
+ * @param cls closure with our `struct TransferTrackContext *`
+ * @param transaction_id of the contract
+ * @param coin_pub public key of the coin
+ * @param amount_with_fee amount the exchange will transfer for this coin
+ * @param transfer_fee fee the exchange will charge for this coin
+ * @param exchange_proof proof from exchange that coin was accepted
+ */
+static void
+check_transfer (void *cls,
+                uint64_t transaction_id,
+                const struct TALER_CoinSpendPublicKeyP *coin_pub,
+                const struct TALER_Amount *amount_with_fee,
+                const struct TALER_Amount *transfer_fee,
+                const json_t *exchange_proof)
+{
+  struct TransferTrackContext *rctx = cls;
+  const struct TALER_TrackTransferDetails *wdd = rctx->current_detail;
+
+  if (0 != memcmp (&wdd->coin_pub,
+                   coin_pub,
+                   sizeof (struct TALER_CoinSpendPublicKeyP)))
+    return; /* not the coin we're looking for */
+  if ( (0 != TALER_amount_cmp (amount_with_fee,
+                               &wdd->coin_value)) ||
+       (0 != TALER_amount_cmp (transfer_fee,
+                               &wdd->coin_fee)) )
+  {
+    /* Disagreement between the exchange and us about how much this
+       coin is worth! */
+    GNUNET_break_op (0);
+    rctx->check_transfer_result = GNUNET_SYSERR;
+    return;
+  }
+  rctx->check_transfer_result = GNUNET_OK;
+}
+
+
+/**
+ * Function called with detailed wire transfer data, including all
+ * of the coin transactions that were combined into the wire transfer.
+ *
+ * @param cls closure
+ * @param http_status HTTP status code we got, 0 on exchange protocol violation
+ * @param exchange_pub public key of the exchange used to sign @a json
+ * @param json original json reply (may include signatures, those have then been
+ *        validated already)
+ * @param wtid extracted wire transfer identifier, or NULL if the exchange could
+ *             not provide any (set only if @a http_status is #MHD_HTTP_OK)
+ * @param total_amount total amount of the wire transfer, or NULL if the exchange could
+ *             not provide any @a wtid (set only if @a http_status is #MHD_HTTP_OK)
+ * @param details_length length of the @a details array
+ * @param details array with details about the combined transactions
+ */
+static void
+wire_transfer_cb (void *cls,
+                  unsigned int http_status,
+                  const struct TALER_ExchangePublicKeyP *exchange_pub,
+                  const json_t *json,
+                  const struct GNUNET_HashCode *h_wire,
+                  const struct TALER_Amount *total_amount,
+                  unsigned int details_length,
+                  const struct TALER_TrackTransferDetails *details)
+{
+  struct TransferTrackContext *rctx = cls;
+  unsigned int i;
+  int ret;
+
+  rctx->wdh = NULL;
+  if (MHD_HTTP_OK != http_status)
+  {
+    resume_track_transfer_with_response
+      (rctx,
+       MHD_HTTP_FAILED_DEPENDENCY,
+       TMH_RESPONSE_make_json_pack ("{s:I, s:O}",
+                                    "exchange_status", (json_int_t) http_status,
+                                    "details", json));
+    return;
+  }
+
+  if (GNUNET_OK !=
+      db->store_transfer_to_proof (db->cls,
+                                   rctx->uri,
+                                   &rctx->wtid,
+                                   exchange_pub,
+                                   json))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Failed to persist wire transfer proof in DB\n");
+  }
+
+  for (i=0;i<details_length;i++)
+  {
+    rctx->current_detail = &details[i];
+    rctx->check_transfer_result = GNUNET_NO;
+    ret = db->find_payments_by_id (rctx,
+                                   details[i].transaction_id,
+                                   &check_transfer,
+                                   rctx);
+    if (GNUNET_SYSERR == ret)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Failed to verify existing payment data in DB\n");
+    }
+    if ( (GNUNET_NO == ret) ||
+         (GNUNET_NO == rctx->check_transfer_result) )
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                  "Failed to find payment data in DB\n");
+    }
+    if (GNUNET_SYSERR == rctx->check_transfer_result)
+    {
+      /* #check_transfer() failed, do something! */
+      GNUNET_break (0);
+      /* FIXME: generate nicer custom response */
+      resume_track_transfer_with_response
+        (rctx,
+         MHD_HTTP_FAILED_DEPENDENCY,
+         TMH_RESPONSE_make_json_pack ("{s:I, s:O}",
+                                      "index", (json_int_t) i,
+                                      "details", json));
+      return;
+    }
+    ret = db->store_coin_to_transfer (db->cls,
+                                      details[i].transaction_id,
+                                      &details[i].coin_pub,
+                                      &rctx->wtid);
+    if (GNUNET_OK != ret)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "Failed to persist coin to wire transfer mapping in DB\n");
+    }
+  }
+  /* FIXME: might want a more custom response here... */
+  resume_track_transfer_with_response
+    (rctx,
+     MHD_HTTP_OK,
+     TMH_RESPONSE_make_json_pack ("{s:I, s:O}",
+                                  "exchange_status", (json_int_t) http_status,
+                                  "details", json));
+}
+
+
+/**
+ * Function called with the result of our exchange lookup.
+ *
+ * @param cls the `struct TransferTrackContext`
+ * @param eh NULL if exchange was not found to be acceptable
+ * @param exchange_trusted #GNUNET_YES if this exchange is trusted by config
+ */
+static void
+process_track_transfer_with_exchange (void *cls,
+                                      struct TALER_EXCHANGE_Handle *eh,
+                                      int exchange_trusted)
+{
+  struct TransferTrackContext *rctx = cls;
+
+  rctx->fo = NULL;
+  rctx->eh = eh;
+  rctx->wdh = TALER_EXCHANGE_track_transfer (eh,
+                                            &rctx->wtid,
+                                            &wire_transfer_cb,
+                                            rctx);
+}
+
+
+/**
+ * Handle a timeout for the processing of the track transfer request.
+ *
+ * @param cls closure
+ */
+static void
+handle_track_transfer_timeout (void *cls)
+{
+  struct TransferTrackContext *rctx = cls;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Resuming /track/transfer with error after timeout\n");
+  rctx->timeout_task = NULL;
+
+  if (NULL != rctx->fo)
+  {
+    TMH_EXCHANGES_find_exchange_cancel (rctx->fo);
+    rctx->fo = NULL;
+  }
+  resume_track_transfer_with_response (rctx,
+                                       MHD_HTTP_SERVICE_UNAVAILABLE,
+                                       TMH_RESPONSE_make_internal_error ("exchange not reachable"));
+}
+
+
+/**
+ * Function called with information about a wire transfer identifier.
+ * Generate a response based on the given @a proof.
+ *
+ * @param cls closure
+ * @param proof proof from exchange about what the wire transfer was for
+ */
+static void
+proof_cb (void *cls,
+          const json_t *proof)
+{
+  struct TransferTrackContext *rctx = cls;
+
+  rctx->response_code = MHD_HTTP_OK;
+  /* FIXME: might want a more custom response here... */
+  rctx->response = TMH_RESPONSE_make_json_pack ("{s:I, s:O}",
+                                                "exchange_status", (json_int_t) MHD_HTTP_OK,
+                                                "details", proof);
+}
+
+
+/**
+ * Manages a /track/transfer call, thus it calls the /track/wtid
+ * offered by the exchange in order to return the set of transfers
+ * (of coins) associated with a given wire transfer.
+ *
+ * @param rh context of the handler
+ * @param connection the MHD connection to handle
+ * @param[in,out] connection_cls the connection's closure (can be updated)
+ * @param upload_data upload data
+ * @param[in,out] upload_data_size number of bytes (left) in @a upload_data
+ * @return MHD result code
+ */
+int
+MH_handler_track_transfer (struct TMH_RequestHandler *rh,
+                           struct MHD_Connection *connection,
+                           void **connection_cls,
+                           const char *upload_data,
+                           size_t *upload_data_size)
+{
+  struct TransferTrackContext *rctx;
+  const char *str;
+  const char *uri;
+  int ret;
+
+  if (NULL == *connection_cls)
+  {
+    rctx = GNUNET_new (struct TransferTrackContext);
+    rctx->hc.cc = &track_transfer_cleanup;
+    rctx->connection = connection;
+    *connection_cls = rctx;
+  }
+  else
+  {
+    /* not first call, recover state */
+    rctx = *connection_cls;
+  }
+
+  if (0 != rctx->response_code)
+  {
+    /* We are *done* processing the request, just queue the response (!) */
+    if (UINT_MAX == rctx->response_code)
+    {
+      GNUNET_break (0);
+      return MHD_NO; /* hard error */
+    }
+    ret = MHD_queue_response (connection,
+                              rctx->response_code,
+                              rctx->response);
+    if (NULL != rctx->response)
+    {
+      MHD_destroy_response (rctx->response);
+      rctx->response = NULL;
+    }
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Queueing response (%u) for /track/transfer (%s).\n",
+                (unsigned int) rctx->response_code,
+                ret ? "OK" : "FAILED");
+    return ret;
+  }
+
+  uri = MHD_lookup_connection_value (connection,
+                                     MHD_GET_ARGUMENT_KIND,
+                                     "exchange");
+  if (NULL == uri)
+    return TMH_RESPONSE_reply_bad_request (connection,
+                                           "exchange argument missing");
+  rctx->uri = GNUNET_strdup (uri);
+
+  str = MHD_lookup_connection_value (connection,
+                                     MHD_GET_ARGUMENT_KIND,
+                                     "wtid");
+  if (NULL == str)
+    return TMH_RESPONSE_reply_bad_request (connection,
+                                           "wtid argument missing");
+  if (GNUNET_OK !=
+      GNUNET_STRINGS_string_to_data (str,
+                                     strlen (str),
+                                     &rctx->wtid,
+                                     sizeof (rctx->wtid)))
+  {
+    return TMH_RESPONSE_reply_bad_request (connection,
+                                           "wtid argument malformed");
+  }
+
+  /* Check if reply is already in database! */
+  ret = db->find_proof_by_wtid (db->cls,
+                                rctx->uri,
+                                &rctx->wtid,
+                                &proof_cb,
+                                rctx);
+  if (0 != rctx->response_code)
+  {
+    ret = MHD_queue_response (connection,
+                              rctx->response_code,
+                              rctx->response);
+    if (NULL != rctx->response)
+    {
+      MHD_destroy_response (rctx->response);
+      rctx->response = NULL;
+    }
+    return ret;
+  }
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Suspending /track/transfer handling while working with the exchange\n");
+  MHD_suspend_connection (connection);
+  rctx->fo = TMH_EXCHANGES_find_exchange (uri,
+                                          &process_track_transfer_with_exchange,
+                                          rctx);
+  rctx->timeout_task
+    = GNUNET_SCHEDULER_add_delayed (TRACK_TIMEOUT,
+                                    &handle_track_transfer_timeout,
+                                    rctx);
+  return MHD_NO;
+}
+
+/* end of taler-merchant-httpd_track-transfer.c */