aboutsummaryrefslogtreecommitdiff
path: root/src/lib/exchange_api_recoup.c
blob: 56499f381b5c2e255082256c3c79c912f36b461f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
/*
  This file is part of TALER
  Copyright (C) 2017-2023 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_recoup.c
 * @brief Implementation of the /recoup request of the exchange's HTTP API
 * @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_common.h"
#include "exchange_api_handle.h"
#include "taler_signatures.h"
#include "exchange_api_curl_defaults.h"


/**
 * @brief A Recoup Handle
 */
struct TALER_EXCHANGE_RecoupHandle
{

  /**
   * The keys of the exchange this request handle will use
   */
  struct TALER_EXCHANGE_Keys *keys;

  /**
   * The url for this request.
   */
  char *url;

  /**
   * Context for #TEH_curl_easy_post(). Keeps the data that must
   * persist for Curl to make the upload.
   */
  struct TALER_CURL_PostContext ctx;

  /**
   * Denomination key of the coin.
   */
  struct TALER_EXCHANGE_DenomPublicKey pk;

  /**
   * Our signature requesting the recoup.
   */
  struct TALER_CoinSpendSignatureP coin_sig;

  /**
   * Handle for the request.
   */
  struct GNUNET_CURL_Job *job;

  /**
   * Function to call with the result.
   */
  TALER_EXCHANGE_RecoupResultCallback cb;

  /**
   * Closure for @a cb.
   */
  void *cb_cls;

  /**
   * Public key of the coin we are trying to get paid back.
   */
  struct TALER_CoinSpendPublicKeyP coin_pub;

};


/**
 * Parse a recoup response.  If it is valid, call the callback.
 *
 * @param ph recoup handle
 * @param json json reply with the signature
 * @return #GNUNET_OK if the signature is valid and we called the callback;
 *         #GNUNET_SYSERR if not (callback must still be called)
 */
static enum GNUNET_GenericReturnValue
process_recoup_response (const struct TALER_EXCHANGE_RecoupHandle *ph,
                         const json_t *json)
{
  struct TALER_EXCHANGE_RecoupResponse rr = {
    .hr.reply = json,
    .hr.http_status = MHD_HTTP_OK
  };
  struct GNUNET_JSON_Specification spec_withdraw[] = {
    GNUNET_JSON_spec_fixed_auto ("reserve_pub",
                                 &rr.details.ok.reserve_pub),
    GNUNET_JSON_spec_end ()
  };

  if (GNUNET_OK !=
      GNUNET_JSON_parse (json,
                         spec_withdraw,
                         NULL, NULL))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  ph->cb (ph->cb_cls,
          &rr);
  return GNUNET_OK;
}


/**
 * Function called when we're done processing the
 * HTTP /recoup request.
 *
 * @param cls the `struct TALER_EXCHANGE_RecoupHandle`
 * @param response_code HTTP response code, 0 on error
 * @param response parsed JSON result, NULL on error
 */
static void
handle_recoup_finished (void *cls,
                        long response_code,
                        const void *response)
{
  struct TALER_EXCHANGE_RecoupHandle *ph = cls;
  const json_t *j = response;
  struct TALER_EXCHANGE_RecoupResponse rr = {
    .hr.reply = j,
    .hr.http_status = (unsigned int) response_code
  };

  ph->job = NULL;
  switch (response_code)
  {
  case 0:
    rr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
    break;
  case MHD_HTTP_OK:
    if (GNUNET_OK !=
        process_recoup_response (ph,
                                 j))
    {
      GNUNET_break_op (0);
      rr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
      rr.hr.http_status = 0;
      break;
    }
    TALER_EXCHANGE_recoup_cancel (ph);
    return;
  case MHD_HTTP_BAD_REQUEST:
    /* This should never happen, either us or the exchange is buggy
       (or API version conflict); just pass JSON reply to the application */
    rr.hr.ec = TALER_JSON_get_error_code (j);
    rr.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_CONFLICT:
    {
      struct TALER_Amount min_key;

      rr.hr.ec = TALER_JSON_get_error_code (j);
      rr.hr.hint = TALER_JSON_get_error_hint (j);
      if (GNUNET_OK !=
          TALER_EXCHANGE_get_min_denomination_ (ph->keys,
                                                &min_key))
      {
        GNUNET_break (0);
        rr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
        rr.hr.http_status = 0;
        break;
      }
      break;
    }
  case MHD_HTTP_FORBIDDEN:
    /* 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 */
    rr.hr.ec = TALER_JSON_get_error_code (j);
    rr.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_NOT_FOUND:
    /* Nothing really to verify, this should never
       happen, we should pass the JSON reply to the application */
    rr.hr.ec = TALER_JSON_get_error_code (j);
    rr.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_GONE:
    /* Kind of normal: the money was already sent to the merchant
       (it was too late for the refund). */
    rr.hr.ec = TALER_JSON_get_error_code (j);
    rr.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_INTERNAL_SERVER_ERROR:
    /* Server had an internal issue; we should retry, but this API
       leaves this to the application */
    rr.hr.ec = TALER_JSON_get_error_code (j);
    rr.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  default:
    /* unexpected response code */
    rr.hr.ec = TALER_JSON_get_error_code (j);
    rr.hr.hint = TALER_JSON_get_error_hint (j);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u/%d for exchange recoup\n",
                (unsigned int) response_code,
                (int) rr.hr.ec);
    GNUNET_break (0);
    break;
  }
  ph->cb (ph->cb_cls,
          &rr);
  TALER_EXCHANGE_recoup_cancel (ph);
}


struct TALER_EXCHANGE_RecoupHandle *
TALER_EXCHANGE_recoup (
  struct GNUNET_CURL_Context *ctx,
  const char *url,
  struct TALER_EXCHANGE_Keys *keys,
  const struct TALER_EXCHANGE_DenomPublicKey *pk,
  const struct TALER_DenominationSignature *denom_sig,
  const struct TALER_ExchangeWithdrawValues *exchange_vals,
  const struct TALER_PlanchetMasterSecretP *ps,
  TALER_EXCHANGE_RecoupResultCallback recoup_cb,
  void *recoup_cb_cls)
{
  struct TALER_EXCHANGE_RecoupHandle *ph;
  struct TALER_DenominationHashP h_denom_pub;
  json_t *recoup_obj;
  CURL *eh;
  char arg_str[sizeof (struct TALER_CoinSpendPublicKeyP) * 2 + 32];
  struct TALER_CoinSpendPrivateKeyP coin_priv;
  union GNUNET_CRYPTO_BlindingSecretP bks;

  ph = GNUNET_new (struct TALER_EXCHANGE_RecoupHandle);
  TALER_planchet_setup_coin_priv (ps,
                                  exchange_vals,
                                  &coin_priv);
  TALER_planchet_blinding_secret_create (ps,
                                         exchange_vals,
                                         &bks);
  GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv.eddsa_priv,
                                      &ph->coin_pub.eddsa_pub);
  TALER_denom_pub_hash (&pk->key,
                        &h_denom_pub);
  TALER_wallet_recoup_sign (&h_denom_pub,
                            &bks,
                            &coin_priv,
                            &ph->coin_sig);
  recoup_obj = GNUNET_JSON_PACK (
    GNUNET_JSON_pack_data_auto ("denom_pub_hash",
                                &h_denom_pub),
    TALER_JSON_pack_denom_sig ("denom_sig",
                               denom_sig),
    TALER_JSON_pack_exchange_withdraw_values ("ewv",
                                              exchange_vals),
    GNUNET_JSON_pack_data_auto ("coin_sig",
                                &ph->coin_sig),
    GNUNET_JSON_pack_data_auto ("coin_blind_key_secret",
                                &bks));
  switch (denom_sig->unblinded_sig->cipher)
  {
  case GNUNET_CRYPTO_BSA_INVALID:
    json_decref (recoup_obj);
    GNUNET_break (0);
    GNUNET_free (ph);
    return NULL;
  case GNUNET_CRYPTO_BSA_RSA:
    break;
  case GNUNET_CRYPTO_BSA_CS:
    {
      union GNUNET_CRYPTO_BlindSessionNonce nonce;

      /* NOTE: this is not elegant, and as per the note in TALER_coin_ev_hash()
         it is not strictly clear that the nonce is needed. Best case would be
         to find a way to include it more 'naturally' somehow, for example with
         the variant union version of bks! */
      TALER_cs_withdraw_nonce_derive (ps,
                                      &nonce.cs_nonce);
      GNUNET_assert (
        0 ==
        json_object_set_new (recoup_obj,
                             "cs_nonce",
                             GNUNET_JSON_from_data_auto (
                               &nonce)));
    }
  }

  {
    char pub_str[sizeof (struct TALER_CoinSpendPublicKeyP) * 2];
    char *end;

    end = GNUNET_STRINGS_data_to_string (
      &ph->coin_pub,
      sizeof (struct TALER_CoinSpendPublicKeyP),
      pub_str,
      sizeof (pub_str));
    *end = '\0';
    GNUNET_snprintf (arg_str,
                     sizeof (arg_str),
                     "coins/%s/recoup",
                     pub_str);
  }

  ph->pk = *pk;
  memset (&ph->pk.key,
          0,
          sizeof (ph->pk.key)); /* zero out, as lifetime cannot be warranted */
  ph->cb = recoup_cb;
  ph->cb_cls = recoup_cb_cls;
  ph->url = TALER_url_join (url,
                            arg_str,
                            NULL);
  if (NULL == ph->url)
  {
    json_decref (recoup_obj);
    GNUNET_free (ph);
    return NULL;
  }
  eh = TALER_EXCHANGE_curl_easy_get_ (ph->url);
  if ( (NULL == eh) ||
       (GNUNET_OK !=
        TALER_curl_easy_post (&ph->ctx,
                              eh,
                              recoup_obj)) )
  {
    GNUNET_break (0);
    if (NULL != eh)
      curl_easy_cleanup (eh);
    json_decref (recoup_obj);
    GNUNET_free (ph->url);
    GNUNET_free (ph);
    return NULL;
  }
  json_decref (recoup_obj);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "URL for recoup: `%s'\n",
              ph->url);
  ph->keys = TALER_EXCHANGE_keys_incref (keys);
  ph->job = GNUNET_CURL_job_add2 (ctx,
                                  eh,
                                  ph->ctx.headers,
                                  &handle_recoup_finished,
                                  ph);
  return ph;
}


void
TALER_EXCHANGE_recoup_cancel (struct TALER_EXCHANGE_RecoupHandle *ph)
{
  if (NULL != ph->job)
  {
    GNUNET_CURL_job_cancel (ph->job);
    ph->job = NULL;
  }
  GNUNET_free (ph->url);
  TALER_curl_easy_post_finished (&ph->ctx);
  TALER_EXCHANGE_keys_decref (ph->keys);
  GNUNET_free (ph);
}


/* end of exchange_api_recoup.c */