summaryrefslogtreecommitdiff
path: root/src/exchange-lib/exchange_api_deposit.c
blob: 76e3e4da92bf8dc728b82f27fd20ff730db84c05 (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
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
/*
  This file is part of TALER
  Copyright (C) 2014, 2015 GNUnet e.V.

  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 exchange-lib/exchange_api_deposit.c
 * @brief Implementation of the /deposit request of the exchange's HTTP API
 * @author Sree Harsha Totakura <sreeharsha@totakura.in>
 * @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 <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"


/**
 * @brief A Deposit Handle
 */
struct TALER_EXCHANGE_DepositHandle
{

  /**
   * The connection to exchange this request handle will use
   */
  struct TALER_EXCHANGE_Handle *exchange;

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

  /**
   * JSON encoding of the request to POST.
   */
  char *json_enc;

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

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

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

  /**
   * Information the exchange should sign in response.
   */
  struct TALER_DepositConfirmationPS depconf;

  /**
   * Value of the /deposit transaction, including fee.
   */
  struct TALER_Amount amount_with_fee;

  /**
   * Total value of the coin being transacted with.
   */
  struct TALER_Amount coin_value;

};


/**
 * Verify that the signature on the "200 OK" response
 * from the exchange is valid.
 *
 * @param dh deposit handle
 * @param json json reply with the signature
 * @param exchange_pub set to the exchange's public key
 * @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
 */
static int
verify_deposit_signature_ok (const struct TALER_EXCHANGE_DepositHandle *dh,
                             const json_t *json,
                             struct TALER_ExchangePublicKeyP *exchange_pub)
{
  struct TALER_ExchangeSignatureP exchange_sig;

  const struct TALER_EXCHANGE_Keys *key_state;
  struct GNUNET_JSON_Specification spec[] = {
    GNUNET_JSON_spec_fixed_auto ("sig", &exchange_sig),
    GNUNET_JSON_spec_fixed_auto ("pub", exchange_pub),
    GNUNET_JSON_spec_end()
  };

  if (GNUNET_OK !=
      GNUNET_JSON_parse (json,
                         spec,
                         NULL, NULL))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  key_state = TALER_EXCHANGE_get_keys (dh->exchange);
  if (GNUNET_OK !=
      TALER_EXCHANGE_test_signing_key (key_state,
                                       exchange_pub))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  if (GNUNET_OK !=
      GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_DEPOSIT,
                                  &dh->depconf.purpose,
                                  &exchange_sig.eddsa_signature,
                                  &exchange_pub->eddsa_pub))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Verify that the signatures on the "403 FORBIDDEN" response from the
 * exchange demonstrating customer double-spending are valid.
 *
 * @param dh deposit handle
 * @param json json reply with the signature(s) and transaction history
 * @return #GNUNET_OK if the signature(s) is valid, #GNUNET_SYSERR if not
 */
static int
verify_deposit_signature_forbidden (const struct TALER_EXCHANGE_DepositHandle *dh,
                                    const json_t *json)
{
  json_t *history;
  struct TALER_Amount total;

  history = json_object_get (json,
                             "history");
  if (GNUNET_OK !=
      TALER_EXCHANGE_verify_coin_history (dh->coin_value.currency,
                                           &dh->depconf.coin_pub,
                                           history,
                                           &total))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  if (GNUNET_OK !=
      TALER_amount_add (&total,
                        &total,
                        &dh->amount_with_fee))
  {
    /* clearly not OK if our transaction would have caused
       the overflow... */
    return GNUNET_OK;
  }

  if (0 >= TALER_amount_cmp (&total,
                             &dh->coin_value))
  {
    /* transaction should have still fit */
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  /* everything OK, proof of double-spending was provided */
  return GNUNET_OK;
}


/**
 * Function called when we're done processing the
 * HTTP /deposit request.
 *
 * @param cls the `struct TALER_EXCHANGE_DepositHandle`
 * @param response_code HTTP response code, 0 on error
 * @param json parsed JSON result, NULL on error
 */
static void
handle_deposit_finished (void *cls,
                         long response_code,
                         const json_t *json)
{
  struct TALER_EXCHANGE_DepositHandle *dh = cls;
  struct TALER_ExchangePublicKeyP exchange_pub;
  struct TALER_ExchangePublicKeyP *ep = NULL;

  dh->job = NULL;
  switch (response_code)
  {
  case 0:
    break;
  case MHD_HTTP_OK:
    if (GNUNET_OK !=
        verify_deposit_signature_ok (dh,
                                     json,
                                     &exchange_pub))
    {
      GNUNET_break_op (0);
      response_code = 0;
    }
    else
    {
      ep = &exchange_pub;
    }
    break;
  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 */
    break;
  case MHD_HTTP_FORBIDDEN:
    /* Double spending; check signatures on transaction history */
    if (GNUNET_OK !=
        verify_deposit_signature_forbidden (dh,
                                            json))
    {
      GNUNET_break_op (0);
      response_code = 0;
    }
    break;
  case MHD_HTTP_UNAUTHORIZED:
    /* 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:
    /* 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",
                (unsigned int) response_code);
    GNUNET_break (0);
    response_code = 0;
    break;
  }
  dh->cb (dh->cb_cls,
          response_code,
	  TALER_JSON_get_error_code (json),
          ep,
          json);
  TALER_EXCHANGE_deposit_cancel (dh);
}


/**
 * Verify signature information about the deposit.
 *
 * @param dki public key information
 * @param amount the amount to be deposited
 * @param h_wire hash of the merchant’s account details
 * @param h_contract_terms hash of the contact of the merchant with the customer (further details are never disclosed to the exchange)
 * @param coin_pub coin’s public key
 * @param denom_pub denomination key with which the coin is signed
 * @param denom_sig exchange’s unblinded signature of the coin
 * @param timestamp timestamp when the deposit was finalized
 * @param merchant_pub the public key of the merchant (used to identify the merchant for refund requests)
 * @param refund_deadline date until which the merchant can issue a refund to the customer via the exchange (can be zero if refunds are not allowed)
 * @param coin_sig the signature made with purpose #TALER_SIGNATURE_WALLET_COIN_DEPOSIT made by the customer with the coin’s private key.
 * @return #GNUNET_OK if signatures are OK, #GNUNET_SYSERR if not
 */
static int
verify_signatures (const struct TALER_EXCHANGE_DenomPublicKey *dki,
                   const struct TALER_Amount *amount,
                   const struct GNUNET_HashCode *h_wire,
                   const struct GNUNET_HashCode *h_contract_terms,
                   const struct TALER_CoinSpendPublicKeyP *coin_pub,
                   const struct TALER_DenominationSignature *denom_sig,
                   const struct TALER_DenominationPublicKey *denom_pub,
                   struct GNUNET_TIME_Absolute timestamp,
                   const struct TALER_MerchantPublicKeyP *merchant_pub,
                   struct GNUNET_TIME_Absolute refund_deadline,
                   const struct TALER_CoinSpendSignatureP *coin_sig)
{
  struct TALER_DepositRequestPS dr;
  struct TALER_CoinPublicInfo coin_info;

  dr.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_DEPOSIT);
  dr.purpose.size = htonl (sizeof (struct TALER_DepositRequestPS));
  dr.h_contract_terms = *h_contract_terms;
  dr.h_wire = *h_wire;
  dr.timestamp = GNUNET_TIME_absolute_hton (timestamp);
  dr.refund_deadline = GNUNET_TIME_absolute_hton (refund_deadline);
  TALER_amount_hton (&dr.amount_with_fee,
                     amount);
  TALER_amount_hton (&dr.deposit_fee,
                     &dki->fee_deposit);
  dr.merchant = *merchant_pub;
  dr.coin_pub = *coin_pub;
  if (GNUNET_OK !=
      GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_WALLET_COIN_DEPOSIT,
                                  &dr.purpose,
                                  &coin_sig->eddsa_signature,
                                  &coin_pub->eddsa_pub))
  {
    GNUNET_break_op (0);
    TALER_LOG_WARNING ("Invalid coin signature on /deposit request!\n");
    {
      TALER_LOG_DEBUG ("... amount_with_fee was %s\n",
                       TALER_amount2s (amount));
      TALER_LOG_DEBUG ("... deposit_fee was %s\n",
                       TALER_amount2s (&dki->fee_deposit));
    }

    return GNUNET_SYSERR;
  }

  /* check coin signature */
  coin_info.coin_pub = *coin_pub;
  coin_info.denom_pub = *denom_pub;
  coin_info.denom_sig = *denom_sig;
  if (GNUNET_YES !=
      TALER_test_coin_valid (&coin_info))
  {
    GNUNET_break_op (0);
    TALER_LOG_WARNING ("Invalid coin passed for /deposit\n");
    return GNUNET_SYSERR;
  }
  if (0 < TALER_amount_cmp (&dki->fee_deposit,
                            amount))
  {
    GNUNET_break_op (0);
    TALER_LOG_WARNING ("Deposit amount smaller than fee\n");
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Submit a deposit permission to the exchange and get the exchange's response.
 * Note that while we return the 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 exchange's reply is not well-formed, we return an
 * HTTP status code of zero to @a cb.
 *
 * We also verify that the @a coin_sig is valid for this deposit
 * request, and that the @a ub_sig is a valid signature for @a
 * coin_pub.  Also, the @a exchange must be ready to operate (i.e.  have
 * finished processing the /keys reply).  If either check fails, we do
 * NOT initiate the transaction with the exchange and instead return NULL.
 *
 * @param exchange the exchange handle; the exchange must be ready to operate
 * @param amount the amount to be deposited
 * @param wire_deadline date until which the merchant would like the exchange to settle the balance (advisory, the exchange cannot be
 *        forced to settle in the past or upon very short notice, but of course a well-behaved exchange will limit aggregation based on the advice received)
 * @param wire_details the merchant’s account details, in a format supported by the exchange
 * @param h_contract_terms hash of the contact of the merchant with the customer (further details are never disclosed to the exchange)
 * @param coin_pub coin’s public key
 * @param denom_pub denomination key with which the coin is signed
 * @param denom_sig exchange’s unblinded signature of the coin
 * @param timestamp timestamp when the contract was finalized, must not be too far in the future
 * @param merchant_pub the public key of the merchant (used to identify the merchant for refund requests)
 * @param refund_deadline date until which the merchant can issue a refund to the customer via the exchange (can be zero if refunds are not allowed); must not be after the @a wire_deadline
 * @param coin_sig the signature made with purpose #TALER_SIGNATURE_WALLET_COIN_DEPOSIT made by the customer with the coin’s private key.
 * @param cb the callback to call when a reply for this request is available
 * @param cb_cls closure for the above callback
 * @return a handle for this request; NULL if the inputs are invalid (i.e.
 *         signatures fail to verify).  In this case, the callback is not called.
 */
struct TALER_EXCHANGE_DepositHandle *
TALER_EXCHANGE_deposit (struct TALER_EXCHANGE_Handle *exchange,
                        const struct TALER_Amount *amount,
                        struct GNUNET_TIME_Absolute wire_deadline,
                        json_t *wire_details,
                        const struct GNUNET_HashCode *h_contract_terms,
                        const struct TALER_CoinSpendPublicKeyP *coin_pub,
                        const struct TALER_DenominationSignature *denom_sig,
                        const struct TALER_DenominationPublicKey *denom_pub,
                        struct GNUNET_TIME_Absolute timestamp,
                        const struct TALER_MerchantPublicKeyP *merchant_pub,
                        struct GNUNET_TIME_Absolute refund_deadline,
                        const struct TALER_CoinSpendSignatureP *coin_sig,
                        TALER_EXCHANGE_DepositResultCallback cb,
                        void *cb_cls)
{
  const struct TALER_EXCHANGE_Keys *key_state;
  const struct TALER_EXCHANGE_DenomPublicKey *dki;
  struct TALER_EXCHANGE_DepositHandle *dh;
  struct GNUNET_CURL_Context *ctx;
  json_t *deposit_obj;
  CURL *eh;
  struct GNUNET_HashCode h_wire;
  struct TALER_Amount amount_without_fee;

  (void) GNUNET_TIME_round_abs (&wire_deadline);
  (void) GNUNET_TIME_round_abs (&refund_deadline);
  GNUNET_assert (refund_deadline.abs_value_us <= wire_deadline.abs_value_us);
  GNUNET_assert (GNUNET_YES ==
		 MAH_handle_is_ready (exchange));
  /* initialize h_wire */
  if (GNUNET_OK !=
      TALER_JSON_hash (wire_details,
                       &h_wire))
  {
    GNUNET_break (0);
    return NULL;
  }
  key_state = TALER_EXCHANGE_get_keys (exchange);
  dki = TALER_EXCHANGE_get_denomination_key (key_state,
                                             denom_pub);
  GNUNET_assert (NULL != dki);
  GNUNET_assert (GNUNET_SYSERR !=
		 TALER_amount_subtract (&amount_without_fee,
					amount,
					&dki->fee_deposit));
  if (GNUNET_OK !=
      verify_signatures (dki,
                         amount,
                         &h_wire,
                         h_contract_terms,
                         coin_pub,
                         denom_sig,
                         denom_pub,
                         timestamp,
                         merchant_pub,
                         refund_deadline,
                         coin_sig))
  {
    GNUNET_break_op (0);
    return NULL;
  }

  deposit_obj = json_pack ("{s:o, s:O," /* f/wire */
                           " s:o, s:o," /* H_wire, h_contract_terms */
                           " s:o, s:o," /* coin_pub, denom_pub */
                           " s:o, s:o," /* ub_sig, timestamp */
                           " s:o," /* merchant_pub */
                           " s:o, s:o," /* refund_deadline, wire_deadline */
                           " s:o}",     /* coin_sig */
                           "contribution", TALER_JSON_from_amount (amount),
                           "wire", wire_details,
                           "H_wire", GNUNET_JSON_from_data_auto (&h_wire),
                           "h_contract_terms", GNUNET_JSON_from_data_auto (h_contract_terms),
                           "coin_pub", GNUNET_JSON_from_data_auto (coin_pub),
                           "denom_pub", GNUNET_JSON_from_rsa_public_key (denom_pub->rsa_public_key),
                           "ub_sig", GNUNET_JSON_from_rsa_signature (denom_sig->rsa_signature),
                           "timestamp", GNUNET_JSON_from_time_abs (timestamp),
                           "merchant_pub", GNUNET_JSON_from_data_auto (merchant_pub),
                           "refund_deadline", GNUNET_JSON_from_time_abs (refund_deadline),
                           "wire_transfer_deadline", GNUNET_JSON_from_time_abs (wire_deadline),
                           "coin_sig", GNUNET_JSON_from_data_auto (coin_sig)
                           );
  if (NULL == deposit_obj)
  {
    GNUNET_break (0);
    return NULL;
  }

  dh = GNUNET_new (struct TALER_EXCHANGE_DepositHandle);
  dh->exchange = exchange;
  dh->cb = cb;
  dh->cb_cls = cb_cls;
  dh->url = MAH_path_to_url (exchange, "/deposit");
  dh->depconf.purpose.size = htonl (sizeof (struct TALER_DepositConfirmationPS));
  dh->depconf.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_DEPOSIT);
  dh->depconf.h_contract_terms = *h_contract_terms;
  dh->depconf.h_wire = h_wire;
  dh->depconf.timestamp = GNUNET_TIME_absolute_hton (timestamp);
  dh->depconf.refund_deadline = GNUNET_TIME_absolute_hton (refund_deadline);
  TALER_amount_hton (&dh->depconf.amount_without_fee,
                     &amount_without_fee);
  dh->depconf.coin_pub = *coin_pub;
  dh->depconf.merchant = *merchant_pub;
  dh->amount_with_fee = *amount;
  dh->coin_value = dki->value;

  eh = curl_easy_init ();
  GNUNET_assert (NULL != (dh->json_enc =
                          json_dumps (deposit_obj,
                                      JSON_COMPACT)));
  json_decref (deposit_obj);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "URL for deposit: `%s'\n",
              dh->url);
  GNUNET_assert (CURLE_OK ==
                 curl_easy_setopt (eh,
                                   CURLOPT_URL,
                                   dh->url));
  GNUNET_assert (CURLE_OK ==
                 curl_easy_setopt (eh,
                                   CURLOPT_POSTFIELDS,
                                   dh->json_enc));
  GNUNET_assert (CURLE_OK ==
                 curl_easy_setopt (eh,
                                   CURLOPT_POSTFIELDSIZE,
                                   strlen (dh->json_enc)));
  ctx = MAH_handle_to_context (exchange);
  dh->job = GNUNET_CURL_job_add (ctx,
				 eh,
				 GNUNET_YES,
				 &handle_deposit_finished,
				 dh);
  return dh;
}


/**
 * Cancel a deposit permission request.  This function cannot be used
 * on a request handle if a response is already served for it.
 *
 * @param deposit the deposit permission request handle
 */
void
TALER_EXCHANGE_deposit_cancel (struct TALER_EXCHANGE_DepositHandle *deposit)
{
  if (NULL != deposit->job)
  {
    GNUNET_CURL_job_cancel (deposit->job);
    deposit->job = NULL;
  }
  GNUNET_free (deposit->url);
  GNUNET_free (deposit->json_enc);
  GNUNET_free (deposit);
}


/* end of exchange_api_deposit.c */