implement /wire api (#3947)

3 files changed, 694 insertions, 0 deletions

diff --git a/src/include/taler_mint_service.h b/src/include/taler_mint_service.h
index 02407a3a9..3f89b0745 100644
--- a/src/include/taler_mint_service.h
+++ b/src/include/taler_mint_service.h
@@ -353,6 +353,88 @@ TALER_MINT_get_denomination_key (const struct TALER_MINT_Keys *keys,
                                  const struct TALER_DenominationPublicKey *pk);
 
 
+/* *********************  /wire *********************** */
+
+
+/**
+ * @brief A Wire format inquiry handle
+ */
+struct TALER_MINT_WireHandle;
+
+
+/**
+ * Callbacks of this type are used to serve the result of submitting a
+ * wire format inquiry request to a mint.
+ *
+ * The callback is invoked multiple times, once for each supported @a
+ * method.  Finally, it is invoked one more time with cls/0/NULL/NULL
+ * to indicate the end of the iteration.  If any request fails to
+ * generate a valid response from the mint, @a http_status will also
+ * be zero and the iteration will also end.  Thus, the iteration
+ * always ends with a final call with an @a http_status of 0. If the
+ * @a http_status is already 0 on the first call, then the response to
+ * the /wire request was invalid.  Later, clients can tell the
+ * difference between @a http_status of 0 indicating a failed
+ * /wire/method request and a regular end of the iteration by @a
+ * method being non-NULL.  If the mint simply correctly asserts that
+ * it does not support any methods, @a method will be NULL but the @a
+ * http_status will be #MHD_HTTP_OK for the first call (followed by a
+ * cls/0/NULL/NULL call to signal the end of the iteration).
+ *
+ * @param cls closure
+ * @param http_status HTTP response code, #MHD_HTTP_OK (200) for successful request;
+ *                    0 if the mint's reply is bogus (fails to follow the protocol)
+ * @param method wire format method supported, i.e. "test" or "sepa", or NULL
+ *            if already the /wire request failed.
+ * @param obj the received JSON reply, if successful this should be the wire
+ *            format details as provided by /wire/METHOD/, or NULL if the
+ *            reply was not in JSON format (in this case, the client might
+ *            want to do an HTTP request to /wire/METHOD/ with a browser to
+ *            provide more information to the user about the @a method).
+ */
+typedef void
+(*TALER_MINT_WireResultCallback) (void *cls,
+                                  unsigned int http_status,
+                                  const char *method,
+                                  json_t *obj);
+
+
+/**
+ * Obtain information about a mint's wire instructions.
+ * A mint may provide wire instructions for creating
+ * a reserve.  The wire instructions also indicate
+ * which wire formats merchants may use with the mint.
+ * This API is typically used by a wallet for wiring
+ * funds, and possibly by a merchant to determine
+ * supported wire formats.
+ *
+ * Note that while we return the (main) response verbatim to the
+ * caller for further processing, we do already verify that the
+ * response is well-formed (i.e. that signatures included in the
+ * response are all valid).  If the mint's reply is not well-formed,
+ * we return an HTTP status code of zero to @a cb.
+ *
+ * @param mint the mint handle; the mint must be ready to operate
+ * @param wire_cb the callback to call when a reply for this request is available
+ * @param wire_cb_cls closure for the above callback
+ * @return a handle for this request
+ */
+struct TALER_MINT_WireHandle *
+TALER_MINT_wire (struct TALER_MINT_Handle *mint,
+                 TALER_MINT_WireResultCallback wire_cb,
+                 void *wire_cb_cls);
+
+
+/**
+ * Cancel a wire information request.  This function cannot be used
+ * on a request handle if a response is already served for it.
+ *
+ * @param wh the wire information request handle
+ */
+void
+TALER_MINT_wire_cancel (struct TALER_MINT_WireHandle *wh);
+
+
 /* *********************  /deposit *********************** */
 
 
diff --git a/src/mint-lib/Makefile.am b/src/mint-lib/Makefile.am
index 0cb83dacb..2729177f8 100644
--- a/src/mint-lib/Makefile.am
+++ b/src/mint-lib/Makefile.am
@@ -22,6 +22,7 @@ libtalermint_la_SOURCES = \
   mint_api_deposit.c \
   mint_api_refresh.c \
   mint_api_refresh_link.c \
+  mint_api_wire.c \
   mint_api_withdraw.c
 
 libtalermint_la_LIBADD = \
diff --git a/src/mint-lib/mint_api_wire.c b/src/mint-lib/mint_api_wire.c
new file mode 100644
index 000000000..7641af7ad
--- /dev/null
+++ b/src/mint-lib/mint_api_wire.c
@@ -0,0 +1,611 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014, 2015 Christian Grothoff (and other contributing authors)
+
+  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, If not, see
+  <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file mint-lib/mint_api_wire.c
+ * @brief Implementation of the /wire request of the mint's HTTP API
+ * @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 "taler_mint_service.h"
+#include "mint_api_common.h"
+#include "mint_api_json.h"
+#include "mint_api_context.h"
+#include "mint_api_handle.h"
+#include "taler_signatures.h"
+
+
+/**
+ * @brief A Wire Handle
+ */
+struct TALER_MINT_WireHandle
+{
+
+  /**
+   * The connection to mint this request handle will use
+   */
+  struct TALER_MINT_Handle *mint;
+
+  /**
+   * The url for this request.
+   */
+  char *url;
+
+  /**
+   * Handle for the request.
+   */
+  struct MAC_Job *job;
+
+  /**
+   * Function to call with the result.
+   */
+  TALER_MINT_WireResultCallback cb;
+
+  /**
+   * Closure for @a cb.
+   */
+  void *cb_cls;
+
+  /**
+   * Download buffer
+   */
+  struct MAC_DownloadBuffer db;
+
+  /**
+   * Set to the "methods" JSON array returned by the
+   * /wire request.
+   */
+  json_t *methods;
+
+  /**
+   * Current iteration offset in the @e methods array.
+   */
+  unsigned int methods_off;
+
+};
+
+
+/**
+ * Verify that the signature on the "200 OK" response
+ * for /wire/sepa from the mint is valid.
+ *
+ * @param wh wire handle
+ * @param json json reply with the signature
+ * @return #GNUNET_SYSERR if @a json is invalid,
+ *         #GNUNET_NO if the method is unknown,
+ *         #GNUNET_OK if the json is valid
+ */
+static int
+verify_wire_sepa_signature_ok (const struct TALER_MINT_WireHandle *wh,
+                               json_t *json)
+{
+  struct TALER_MasterSignatureP mint_sig;
+  struct TALER_MasterWireSepaDetailsPS mp;
+  const char *receiver_name;
+  const char *iban;
+  const char *bic;
+  const struct TALER_MINT_Keys *key_state;
+  struct GNUNET_HashContext *hc;
+  struct MAJ_Specification spec[] = {
+    MAJ_spec_fixed_auto ("sig", &mint_sig),
+    MAJ_spec_string ("receiver_name", &receiver_name),
+    MAJ_spec_string ("iban", &iban),
+    MAJ_spec_string ("bic", &bic),
+    MAJ_spec_end
+  };
+
+  if (GNUNET_OK !=
+      MAJ_parse_json (json,
+                      spec))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
+
+  key_state = TALER_MINT_get_keys (wh->mint);
+  mp.purpose.purpose = htonl (TALER_SIGNATURE_MASTER_SEPA_DETAILS);
+  mp.purpose.size = htonl (sizeof (struct TALER_MasterWireSepaDetailsPS));
+  hc = GNUNET_CRYPTO_hash_context_start ();
+  GNUNET_CRYPTO_hash_context_read (hc,
+                                   receiver_name,
+                                   strlen (receiver_name) + 1);
+  GNUNET_CRYPTO_hash_context_read (hc,
+                                   iban,
+                                   strlen (iban) + 1);
+  GNUNET_CRYPTO_hash_context_read (hc,
+                                   bic,
+                                   strlen (bic) + 1);
+  GNUNET_CRYPTO_hash_context_finish (hc,
+                                     &mp.h_sepa_details);
+
+  if (GNUNET_OK !=
+      GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MASTER_SEPA_DETAILS,
+                                  &mp.purpose,
+                                  &mint_sig.eddsa_signature,
+                                  &key_state->master_pub.eddsa_pub))
+  {
+    GNUNET_break_op (0);
+    MAJ_parse_free (spec);
+    return GNUNET_SYSERR;
+  }
+  MAJ_parse_free (spec);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Verify that the signature on the "200 OK" response
+ * for /wire/METHOD from the mint is valid.
+ *
+ * @param wh wire handle with key material
+ * @param method method to verify the reply for
+ * @param json json reply with the signature
+ * @return #GNUNET_SYSERR if @a json is invalid,
+ *         #GNUNET_NO if the method is unknown,
+ *         #GNUNET_OK if the json is valid
+ */
+static int
+verify_wire_method_signature_ok (const struct TALER_MINT_WireHandle *wh,
+                                 const char *method,
+                                 json_t *json)
+{
+  struct
+  {
+    /**
+     * Name fo the method.
+     */
+    const char *method;
+
+    /**
+     * Handler to invoke to verify signature.
+     *
+     * @param wh wire handle with key material
+     * @param json json reply with signature to verify
+     */
+    int (*handler)(const struct TALER_MINT_WireHandle *wh,
+                   json_t *json);
+  } handlers[] = {
+    { "sepa", &verify_wire_sepa_signature_ok },
+    { NULL, NULL }
+  };
+  unsigned int i;
+
+  for (i=0;NULL != handlers[i].method; i++)
+    if (0 == strcasecmp (handlers[i].method,
+                         method))
+      return handlers[i].handler (wh,
+                                  json);
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Wire transfer method `%s' not supported\n",
+              method);
+  return GNUNET_NO;
+}
+
+
+/**
+ * Perform the next /wire/method request or signal
+ * the end of the iteration.
+ *
+ * @param wh the wire handle
+ * @return a handle for this request
+ */
+static void
+request_wire_method (struct TALER_MINT_WireHandle *wh);
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /wire/METHOD request.
+ *
+ * @param cls the `struct TALER_MINT_WireHandle`
+ * @param eh the curl request handle
+ */
+static void
+handle_wire_method_finished (void *cls,
+                             CURL *eh)
+{
+  struct TALER_MINT_WireHandle *wh = cls;
+  long response_code;
+  json_t *json;
+
+  wh->job = NULL;
+  json = MAC_download_get_result (&wh->db,
+                                  eh,
+                                  &response_code);
+  switch (response_code)
+  {
+  case 0:
+    break;
+  case MHD_HTTP_OK:
+    {
+      const char *method;
+
+      method = json_string_value (json_array_get (wh->methods,
+                                                  wh->methods_off - 1));
+      if (GNUNET_OK !=
+          verify_wire_method_signature_ok (wh,
+                                           method,
+                                           json))
+      {
+        GNUNET_break_op (0);
+        response_code = 0;
+        break;
+      }
+      break;
+    }
+  case MHD_HTTP_FOUND:
+    /* /wire/test returns a 302 redirect, we should just give
+       this information back to the callback below */
+    break;
+  case MHD_HTTP_BAD_REQUEST:
+    /* This should never happen, either us or the mint is buggy
+       (or API version conflict); just pass JSON reply to the application */
+    break;
+  case MHD_HTTP_NOT_FOUND:
+    /* Nothing really to verify, this should never
+       happen, we should pass the JSON reply to the application */
+    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",
+                response_code);
+    GNUNET_break (0);
+    response_code = 0;
+    break;
+  }
+  if (0 == response_code)
+  {
+    /* signal end of iteration */
+    wh->cb (wh->cb_cls,
+            0,
+            NULL,
+            NULL);
+    json_decref (json);
+    TALER_MINT_wire_cancel (wh);
+  }
+  /* pass on successful reply */
+  wh->cb (wh->cb_cls,
+          response_code,
+          NULL,
+          json);
+  /* trigger request for the next /wire/method */
+  request_wire_method (wh);
+}
+
+
+/**
+ * Perform the next /wire/method request or signal
+ * the end of the iteration.
+ *
+ * @param wh the wire handle
+ * @return a handle for this request
+ */
+static void
+request_wire_method (struct TALER_MINT_WireHandle *wh)
+{
+  struct TALER_MINT_Context *ctx;
+  CURL *eh;
+  char *path;
+
+  if (json_array_size (wh->methods) <= wh->methods_off)
+  {
+    /* we are done, signal end of iteration */
+    wh->cb (wh->cb_cls,
+            0,
+            NULL,
+            NULL);
+    TALER_MINT_wire_cancel (wh);
+    return;
+  }
+  GNUNET_free_non_null (wh->db.buf);
+  wh->db.buf = NULL;
+  wh->db.buf_size = 0;
+  wh->db.eno = 0;
+  GNUNET_free_non_null (wh->url);
+  GNUNET_asprintf (&path,
+                   "/wire/%s",
+                   json_string_value (json_array_get (wh->methods,
+                                                      wh->methods_off++)));
+  wh->url = MAH_path_to_url (wh->mint,
+                             path);
+  GNUNET_free (path);
+
+  eh = curl_easy_init ();
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_URL,
+                                   wh->url));
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_WRITEFUNCTION,
+                                   &MAC_download_cb));
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_WRITEDATA,
+                                   &wh->db));
+  ctx = MAH_handle_to_context (wh->mint);
+  wh->job = MAC_job_add (ctx,
+                         eh,
+                         GNUNET_YES,
+                         &handle_wire_method_finished,
+                         wh);
+}
+
+
+/**
+ * Verify that the signature on the "200 OK" response
+ * for /wire from the mint is valid.
+ *
+ * @param wh wire handle
+ * @param json json reply with the signature
+ * @return NULL if @a json is invalid, otherwise the
+ *         "methods" array (with an RC of 1)
+ */
+static json_t *
+verify_wire_signature_ok (const struct TALER_MINT_WireHandle *wh,
+                          json_t *json)
+{
+  struct TALER_MintSignatureP mint_sig;
+  struct TALER_MintPublicKeyP mint_pub;
+  struct TALER_MintWireSupportMethodsPS mp;
+  json_t *methods;
+  const struct TALER_MINT_Keys *key_state;
+  struct GNUNET_HashContext *hc;
+  struct MAJ_Specification spec[] = {
+    MAJ_spec_fixed_auto ("sig", &mint_sig),
+    MAJ_spec_fixed_auto ("pub", &mint_pub),
+    MAJ_spec_json ("methods", &methods),
+    MAJ_spec_end
+  };
+  unsigned int i;
+
+  if (GNUNET_OK !=
+      MAJ_parse_json (json,
+                      spec))
+  {
+    GNUNET_break_op (0);
+    return NULL;
+  }
+  if (! json_is_array (methods))
+  {
+    GNUNET_break_op (0);
+    MAJ_parse_free (spec);
+    return NULL;
+  }
+
+  key_state = TALER_MINT_get_keys (wh->mint);
+  if (GNUNET_OK !=
+      TALER_MINT_test_signing_key (key_state,
+                                   &mint_pub))
+  {
+    GNUNET_break_op (0);
+    return NULL;
+  }
+  hc = GNUNET_CRYPTO_hash_context_start ();
+  for (i=0;i<json_array_size (methods);i++)
+  {
+    const json_t *element = json_array_get (methods, i);
+    const char *method;
+
+    if (! json_is_string (element))
+    {
+      GNUNET_CRYPTO_hash_context_abort (hc);
+      GNUNET_break_op (0);
+      MAJ_parse_free (spec);
+      return NULL;
+    }
+    method = json_string_value (element);
+    GNUNET_CRYPTO_hash_context_read (hc,
+                                     method,
+                                     strlen (method) + 1);
+  }
+  mp.purpose.purpose = htonl (TALER_SIGNATURE_MINT_WIRE_TYPES);
+  mp.purpose.size = htonl (sizeof (struct TALER_MintWireSupportMethodsPS));
+  GNUNET_CRYPTO_hash_context_finish (hc,
+                                     &mp.h_wire_types);
+
+  if (GNUNET_OK !=
+      GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MINT_WIRE_TYPES,
+                                  &mp.purpose,
+                                  &mint_sig.eddsa_signature,
+                                  &mint_pub.eddsa_pub))
+  {
+    GNUNET_break_op (0);
+    MAJ_parse_free (spec);
+    return NULL;
+  }
+  return methods;
+}
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /wire request.
+ *
+ * @param cls the `struct TALER_MINT_WireHandle`
+ * @param eh the curl request handle
+ */
+static void
+handle_wire_finished (void *cls,
+                      CURL *eh)
+{
+  struct TALER_MINT_WireHandle *wh = cls;
+  long response_code;
+  json_t *json;
+
+  wh->job = NULL;
+  json = MAC_download_get_result (&wh->db,
+                                  eh,
+                                  &response_code);
+  switch (response_code)
+  {
+  case 0:
+    break;
+  case MHD_HTTP_OK:
+    {
+      json_t *methods;
+
+      if (NULL ==
+          (methods = verify_wire_signature_ok (wh,
+                                               json)))
+      {
+        GNUNET_break_op (0);
+        response_code = 0;
+        break;
+      }
+      wh->methods = methods;
+      request_wire_method (wh);
+      return;
+    }
+    break;
+  case MHD_HTTP_BAD_REQUEST:
+    /* This should never happen, either us or the mint is buggy
+       (or API version conflict); just pass JSON reply to the application */
+    break;
+  case MHD_HTTP_NOT_FOUND:
+    /* Nothing really to verify, this should never
+       happen, we should pass the JSON reply to the application */
+    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",
+                response_code);
+    GNUNET_break (0);
+    response_code = 0;
+    break;
+  }
+  if (0 != response_code)
+  {
+    /* pass on successful reply */
+    wh->cb (wh->cb_cls,
+            response_code,
+            NULL,
+            json);
+  }
+  /* signal end of iteration */
+  wh->cb (wh->cb_cls,
+          0,
+          NULL,
+          NULL);
+  json_decref (json);
+  TALER_MINT_wire_cancel (wh);
+}
+
+
+/**
+ * Obtain information about a mint's wire instructions.
+ * A mint may provide wire instructions for creating
+ * a reserve.  The wire instructions also indicate
+ * which wire formats merchants may use with the mint.
+ * This API is typically used by a wallet for wiring
+ * funds, and possibly by a merchant to determine
+ * supported wire formats.
+ *
+ * Note that while we return the (main) response verbatim to the
+ * caller for further processing, we do already verify that the
+ * response is well-formed (i.e. that signatures included in the
+ * response are all valid).  If the mint's reply is not well-formed,
+ * we return an HTTP status code of zero to @a cb.
+ *
+ * @param mint the mint handle; the mint must be ready to operate
+ * @param wire_cb the callback to call when a reply for this request is available
+ * @param wire_cb_cls closure for the above callback
+ * @return a handle for this request
+ */
+struct TALER_MINT_WireHandle *
+TALER_MINT_wire (struct TALER_MINT_Handle *mint,
+                 TALER_MINT_WireResultCallback wire_cb,
+                 void *wire_cb_cls)
+{
+  struct TALER_MINT_WireHandle *wh;
+  struct TALER_MINT_Context *ctx;
+  CURL *eh;
+
+  if (GNUNET_YES !=
+      MAH_handle_is_ready (mint))
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  wh = GNUNET_new (struct TALER_MINT_WireHandle);
+  wh->mint = mint;
+  wh->cb = wire_cb;
+  wh->cb_cls = wire_cb_cls;
+  wh->url = MAH_path_to_url (mint, "/wire");
+
+  eh = curl_easy_init ();
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_URL,
+                                   wh->url));
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_WRITEFUNCTION,
+                                   &MAC_download_cb));
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_WRITEDATA,
+                                   &wh->db));
+  ctx = MAH_handle_to_context (mint);
+  wh->job = MAC_job_add (ctx,
+                         eh,
+                         GNUNET_YES,
+                         &handle_wire_finished,
+                         wh);
+  return wh;
+}
+
+
+/**
+ * Cancel a wire information request.  This function cannot be used
+ * on a request handle if a response is already served for it.
+ *
+ * @param wire the wire information request handle
+ */
+void
+TALER_MINT_wire_cancel (struct TALER_MINT_WireHandle *wire)
+{
+  if (NULL != wire->job)
+  {
+    MAC_job_cancel (wire->job);
+    wire->job = NULL;
+  }
+  if (NULL != wire->methods)
+  {
+    json_decref (wire->methods);
+    wire->methods = NULL;
+  }
+  GNUNET_free_non_null (wire->db.buf);
+  GNUNET_free (wire->url);
+  GNUNET_free (wire);
+}
+
+
+/* end of mint_api_wire.c */