aboutsummaryrefslogtreecommitdiff
path: root/src/lib/exchange_api_withdraw2.c
blob: c8eb3182299e3a69f3b3a43d0e8b1cb34982a045 (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
/*
  This file is part of TALER
  Copyright (C) 2014-2021 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_withdraw2.c
 * @brief Implementation of /reserves/$RESERVE_PUB/withdraw requests without blinding/unblinding
 * @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_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 Withdraw Handle
 */
struct TALER_EXCHANGE_Withdraw2Handle
{

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

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

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

  /**
   * Function to call with the result.
   */
  TALER_EXCHANGE_Withdraw2Callback cb;

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

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

  /**
   * Total amount requested (value plus withdraw fee).
   */
  struct TALER_Amount requested_amount;

  /**
   * Public key of the reserve we are withdrawing from.
   */
  struct TALER_ReservePublicKeyP reserve_pub;

};


/**
 * We got a 200 OK response for the /reserves/$RESERVE_PUB/withdraw operation.
 * Extract the coin's signature and return it to the caller.  The signature we
 * get from the exchange is for the blinded value.  Thus, we first must
 * unblind it and then should verify its validity against our coin's hash.
 *
 * If everything checks out, we return the unblinded signature
 * to the application via the callback.
 *
 * @param wh operation handle
 * @param json reply from the exchange
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
 */
static enum GNUNET_GenericReturnValue
reserve_withdraw_ok (struct TALER_EXCHANGE_Withdraw2Handle *wh,
                     const json_t *json)
{
  struct TALER_BlindedDenominationSignature blind_sig;
  struct GNUNET_JSON_Specification spec[] = {
    TALER_JSON_spec_blinded_denom_sig ("ev_sig",
                                       &blind_sig),
    GNUNET_JSON_spec_end ()
  };
  struct TALER_EXCHANGE_HttpResponse hr = {
    .reply = json,
    .http_status = MHD_HTTP_OK
  };

  if (GNUNET_OK !=
      GNUNET_JSON_parse (json,
                         spec,
                         NULL, NULL))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }

  /* signature is valid, return it to the application */
  wh->cb (wh->cb_cls,
          &hr,
          &blind_sig);
  /* make sure callback isn't called again after return */
  wh->cb = NULL;
  GNUNET_JSON_parse_free (spec);
  return GNUNET_OK;
}


/**
 * We got a 409 CONFLICT response for the /reserves/$RESERVE_PUB/withdraw operation.
 * Check the signatures on the withdraw transactions in the provided
 * history and that the balances add up.  We don't do anything directly
 * with the information, as the JSON will be returned to the application.
 * However, our job is ensuring that the exchange followed the protocol, and
 * this in particular means checking all of the signatures in the history.
 *
 * @param wh operation handle
 * @param json reply from the exchange
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
 */
static enum GNUNET_GenericReturnValue
reserve_withdraw_payment_required (
  struct TALER_EXCHANGE_Withdraw2Handle *wh,
  const json_t *json)
{
  struct TALER_Amount balance;
  struct TALER_Amount balance_from_history;
  json_t *history;
  size_t len;
  struct GNUNET_JSON_Specification spec[] = {
    TALER_JSON_spec_amount_any ("balance", &balance),
    GNUNET_JSON_spec_end ()
  };

  if (GNUNET_OK !=
      GNUNET_JSON_parse (json,
                         spec,
                         NULL, NULL))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  history = json_object_get (json,
                             "history");
  if (NULL == history)
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }

  /* go over transaction history and compute
     total incoming and outgoing amounts */
  len = json_array_size (history);
  {
    struct TALER_EXCHANGE_ReserveHistory *rhistory;

    /* Use heap allocation as "len" may be very big and thus this may
       not fit on the stack. Use "GNUNET_malloc_large" as a malicious
       exchange may theoretically try to crash us by giving a history
       that does not fit into our memory. */
    rhistory = GNUNET_malloc_large (sizeof (struct
                                            TALER_EXCHANGE_ReserveHistory)
                                    * len);
    if (NULL == rhistory)
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }

    if (GNUNET_OK !=
        TALER_EXCHANGE_parse_reserve_history (wh->exchange,
                                              history,
                                              &wh->reserve_pub,
                                              balance.currency,
                                              &balance_from_history,
                                              len,
                                              rhistory))
    {
      GNUNET_break_op (0);
      TALER_EXCHANGE_free_reserve_history (rhistory,
                                           len);
      return GNUNET_SYSERR;
    }
    TALER_EXCHANGE_free_reserve_history (rhistory,
                                         len);
  }

  if (0 !=
      TALER_amount_cmp (&balance_from_history,
                        &balance))
  {
    /* exchange cannot add up balances!? */
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  /* Check that funds were really insufficient */
  if (0 >= TALER_amount_cmp (&wh->requested_amount,
                             &balance))
  {
    /* Requested amount is smaller or equal to reported balance,
       so this should not have failed. */
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Function called when we're done processing the
 * HTTP /reserves/$RESERVE_PUB/withdraw request.
 *
 * @param cls the `struct TALER_EXCHANGE_WithdrawHandle`
 * @param response_code HTTP response code, 0 on error
 * @param response parsed JSON result, NULL on error
 */
static void
handle_reserve_withdraw_finished (void *cls,
                                  long response_code,
                                  const void *response)
{
  struct TALER_EXCHANGE_Withdraw2Handle *wh = cls;
  const json_t *j = response;
  struct TALER_EXCHANGE_HttpResponse hr = {
    .reply = j,
    .http_status = (unsigned int) response_code
  };

  wh->job = NULL;
  switch (response_code)
  {
  case 0:
    hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
    break;
  case MHD_HTTP_OK:
    if (GNUNET_OK !=
        reserve_withdraw_ok (wh,
                             j))
    {
      GNUNET_break_op (0);
      hr.http_status = 0;
      hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
      break;
    }
    GNUNET_assert (NULL == wh->cb);
    TALER_EXCHANGE_withdraw2_cancel (wh);
    return;
  case MHD_HTTP_ACCEPTED:
    /* only validate reply is well-formed */
    {
      uint64_t ptu;
      struct GNUNET_JSON_Specification spec[] = {
        GNUNET_JSON_spec_uint64 ("payment_target_uuid",
                                 &ptu),
        GNUNET_JSON_spec_end ()
      };

      if (GNUNET_OK !=
          GNUNET_JSON_parse (j,
                             spec,
                             NULL, NULL))
      {
        GNUNET_break_op (0);
        hr.http_status = 0;
        hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
        break;
      }
    }
    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 */
    hr.ec = TALER_JSON_get_error_code (j);
    hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_FORBIDDEN:
    GNUNET_break_op (0);
    /* 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 */
    hr.ec = TALER_JSON_get_error_code (j);
    hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_NOT_FOUND:
    /* Nothing really to verify, the exchange basically just says
       that it doesn't know this reserve.  Can happen if we
       query before the wire transfer went through.
       We should simply pass the JSON reply to the application. */
    hr.ec = TALER_JSON_get_error_code (j);
    hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_CONFLICT:
    /* The exchange says that the reserve has insufficient funds;
       check the signatures in the history... */
    if (GNUNET_OK !=
        reserve_withdraw_payment_required (wh,
                                           j))
    {
      GNUNET_break_op (0);
      hr.http_status = 0;
      hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
    }
    else
    {
      hr.ec = TALER_JSON_get_error_code (j);
      hr.hint = TALER_JSON_get_error_hint (j);
    }
    break;
  case MHD_HTTP_GONE:
    /* could happen if denomination was revoked */
    /* Note: one might want to check /keys for revocation
       signature here, alas tricky in case our /keys
       is outdated => left to clients */
    hr.ec = TALER_JSON_get_error_code (j);
    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 */
    hr.ec = TALER_JSON_get_error_code (j);
    hr.hint = TALER_JSON_get_error_hint (j);
    break;
  default:
    /* unexpected response code */
    GNUNET_break_op (0);
    hr.ec = TALER_JSON_get_error_code (j);
    hr.hint = TALER_JSON_get_error_hint (j);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u/%d for exchange withdraw\n",
                (unsigned int) response_code,
                (int) hr.ec);
    break;
  }
  if (NULL != wh->cb)
  {
    wh->cb (wh->cb_cls,
            &hr,
            NULL);
    wh->cb = NULL;
  }
  TALER_EXCHANGE_withdraw2_cancel (wh);
}


struct TALER_EXCHANGE_Withdraw2Handle *
TALER_EXCHANGE_withdraw2 (
  struct TALER_EXCHANGE_Handle *exchange,
  const struct TALER_PlanchetDetail *pd,
  const struct TALER_ReservePrivateKeyP *reserve_priv,
  TALER_EXCHANGE_Withdraw2Callback res_cb,
  void *res_cb_cls)
{
  struct TALER_EXCHANGE_Withdraw2Handle *wh;
  const struct TALER_EXCHANGE_Keys *keys;
  const struct TALER_EXCHANGE_DenomPublicKey *dk;
  struct TALER_ReserveSignatureP reserve_sig;
  char arg_str[sizeof (struct TALER_ReservePublicKeyP) * 2 + 32];

  keys = TALER_EXCHANGE_get_keys (exchange);
  if (NULL == keys)
  {
    GNUNET_break (0);
    return NULL;
  }
  dk = TALER_EXCHANGE_get_denomination_key_by_hash (keys,
                                                    &pd->denom_pub_hash);
  if (NULL == dk)
  {
    GNUNET_break (0);
    return NULL;
  }
  wh = GNUNET_new (struct TALER_EXCHANGE_Withdraw2Handle);
  wh->exchange = exchange;
  wh->cb = res_cb;
  wh->cb_cls = res_cb_cls;
  /* Compute how much we expected to charge to the reserve */
  if (0 >
      TALER_amount_add (&wh->requested_amount,
                        &dk->value,
                        &dk->fee_withdraw))
  {
    /* Overflow here? Very strange, our CPU must be fried... */
    GNUNET_break (0);
    GNUNET_free (wh);
    return NULL;
  }

  GNUNET_CRYPTO_eddsa_key_get_public (&reserve_priv->eddsa_priv,
                                      &wh->reserve_pub.eddsa_pub);

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

    end = GNUNET_STRINGS_data_to_string (
      &wh->reserve_pub,
      sizeof (struct TALER_ReservePublicKeyP),
      pub_str,
      sizeof (pub_str));
    *end = '\0';
    GNUNET_snprintf (arg_str,
                     sizeof (arg_str),
                     "/reserves/%s/withdraw",
                     pub_str);
  }
  {
    struct TALER_WithdrawRequestPS req = {
      .purpose.size = htonl (sizeof (struct TALER_WithdrawRequestPS)),
      .purpose.purpose = htonl (TALER_SIGNATURE_WALLET_RESERVE_WITHDRAW),
      .reserve_pub = wh->reserve_pub,
      .h_denomination_pub = pd->denom_pub_hash
    };

    TALER_amount_hton (&req.amount_with_fee,
                       &wh->requested_amount);
    TALER_coin_ev_hash (
      pd->blinded_planchet.details.rsa_blinded_planchet.blinded_msg,
      pd->blinded_planchet.details.rsa_blinded_planchet.
      blinded_msg_size,
      &req.h_coin_envelope);
    GNUNET_CRYPTO_eddsa_sign (&reserve_priv->eddsa_priv,
                              &req,
                              &reserve_sig.eddsa_signature);
  }

  {
    json_t *withdraw_obj;

    withdraw_obj = GNUNET_JSON_PACK (
      GNUNET_JSON_pack_data_auto ("denom_pub_hash",
                                  &pd->denom_pub_hash),
      GNUNET_JSON_pack_data_varsize ("coin_ev",
                                     pd->blinded_planchet.details.
                                     rsa_blinded_planchet.blinded_msg,
                                     pd->blinded_planchet.details.
                                     rsa_blinded_planchet.blinded_msg_size),
      GNUNET_JSON_pack_data_auto ("reserve_sig",
                                  &reserve_sig));
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Attempting to withdraw from reserve %s\n",
                TALER_B2S (&wh->reserve_pub));
    wh->url = TEAH_path_to_url (exchange,
                                arg_str);
    if (NULL == wh->url)
    {
      json_decref (withdraw_obj);
      GNUNET_free (wh);
      return NULL;
    }
    {
      CURL *eh;
      struct GNUNET_CURL_Context *ctx;

      ctx = TEAH_handle_to_context (exchange);
      eh = TALER_EXCHANGE_curl_easy_get_ (wh->url);
      if ( (NULL == eh) ||
           (GNUNET_OK !=
            TALER_curl_easy_post (&wh->post_ctx,
                                  eh,
                                  withdraw_obj)) )
      {
        GNUNET_break (0);
        if (NULL != eh)
          curl_easy_cleanup (eh);
        json_decref (withdraw_obj);
        GNUNET_free (wh->url);
        GNUNET_free (wh);
        return NULL;
      }
      json_decref (withdraw_obj);
      wh->job = GNUNET_CURL_job_add2 (ctx,
                                      eh,
                                      wh->post_ctx.headers,
                                      &handle_reserve_withdraw_finished,
                                      wh);
    }
  }
  return wh;
}


void
TALER_EXCHANGE_withdraw2_cancel (struct TALER_EXCHANGE_Withdraw2Handle *wh)
{
  if (NULL != wh->job)
  {
    GNUNET_CURL_job_cancel (wh->job);
    wh->job = NULL;
  }
  GNUNET_free (wh->url);
  TALER_curl_easy_post_finished (&wh->post_ctx);
  GNUNET_free (wh);
}