aboutsummaryrefslogtreecommitdiff
path: root/src/exchange-lib/exchange_api_refresh_link.c
blob: 8bb40d7f4a70dba8496f62aa8a547d7edf2a34ec (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
/*
  This file is part of TALER
  Copyright (C) 2015, 2016 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, If not, see
  <http://www.gnu.org/licenses/>
*/
/**
 * @file exchange-lib/exchange_api_refresh_link.c
 * @brief Implementation of the /refresh/link request of the exchange's HTTP API
 * @author Christian Grothoff
 */
#include "platform.h"
#include <curl/curl.h>
#include <microhttpd.h> /* just for HTTP status codes */
#include <gnunet/gnunet_util_lib.h>
#include "taler_exchange_service.h"
#include "taler_json_lib.h"
#include "exchange_api_context.h"
#include "exchange_api_handle.h"
#include "taler_signatures.h"


/**
 * @brief A /refresh/link Handle
 */
struct TALER_EXCHANGE_RefreshLinkHandle
{

  /**
   * 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 MAC_Job *job;

  /**
   * Function to call with the result.
   */
  TALER_EXCHANGE_RefreshLinkCallback link_cb;

  /**
   * Closure for @e cb.
   */
  void *link_cb_cls;

  /**
   * Download buffer
   */
  struct MAC_DownloadBuffer db;

  /**
   * Private key of the coin, required to decode link information.
   */
  struct TALER_CoinSpendPrivateKeyP coin_priv;

};


/**
 * Parse the provided linkage data from the "200 OK" response
 * for one of the coins.
 *
 * @param rlh refresh link handle
 * @param json json reply with the data for one coin
 * @param trans_pub our transfer public key
 * @param secret_enc encrypted key to decrypt link data
 * @param[out] coin_priv where to return private coin key
 * @param[out] sig where to return private coin signature
 * @param[out] pub where to return the public key for the coin
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
static int
parse_refresh_link_coin (const struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
                         json_t *json,
                         const struct TALER_TransferPublicKeyP *trans_pub,
                         const struct TALER_EncryptedLinkSecretP *secret_enc,
                         struct TALER_CoinSpendPrivateKeyP *coin_priv,
                         struct TALER_DenominationSignature *sig,
                         struct TALER_DenominationPublicKey *pub)
{
  void *link_enc;
  size_t link_enc_size;
  struct GNUNET_CRYPTO_RsaSignature *bsig;
  struct GNUNET_CRYPTO_RsaPublicKey *rpub;
  struct GNUNET_JSON_Specification spec[] = {
    GNUNET_JSON_spec_varsize ("link_enc", &link_enc, &link_enc_size),
    GNUNET_JSON_spec_rsa_public_key ("denom_pub", &rpub),
    GNUNET_JSON_spec_rsa_signature ("ev_sig", &bsig),
    GNUNET_JSON_spec_end()
  };
  struct TALER_RefreshLinkEncrypted *rle;
  struct TALER_RefreshLinkDecrypted *rld;
  struct TALER_LinkSecretP secret;

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

  /* decode and decrypt link data */
  rle = TALER_refresh_link_encrypted_decode (link_enc,
                                             link_enc_size);
  if (NULL == rle)
  {
    GNUNET_break_op (0);
    GNUNET_JSON_parse_free (spec);
    return GNUNET_SYSERR;
  }
  if (GNUNET_OK !=
      TALER_link_decrypt_secret2 (secret_enc,
                                  trans_pub,
                                  &rlh->coin_priv,
                                  &secret))
  {
    GNUNET_break_op (0);
    GNUNET_JSON_parse_free (spec);
    return GNUNET_SYSERR;
  }
  rld = TALER_refresh_decrypt (rle,
                               &secret);
  if (NULL == rld)
  {
    GNUNET_break_op (0);
    GNUNET_JSON_parse_free (spec);
    return GNUNET_SYSERR;
  }

  /* extract coin and signature */
  *coin_priv = rld->coin_priv;
  sig->rsa_signature
    = GNUNET_CRYPTO_rsa_unblind (bsig,
                                 rld->blinding_key.rsa_blinding_key,
                                 rpub);

  /* clean up */
  GNUNET_free (rld);
  pub->rsa_public_key = GNUNET_CRYPTO_rsa_public_key_dup (rpub);
  GNUNET_JSON_parse_free (spec);
  return GNUNET_OK;
}


/**
 * Parse the provided linkage data from the "200 OK" response
 * for one of the coins.
 *
 * @param[in,out] rlh refresh link handle (callback may be zero'ed out)
 * @param json json reply with the data for one coin
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
static int
parse_refresh_link_ok (struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
                       json_t *json)
{
  unsigned int session;
  unsigned int num_coins;
  int ret;

  if (! json_is_array (json))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  num_coins = 0;
  /* Theoretically, a coin may have been melted repeatedly
     into different sessions; so the response is an array
     which contains information by melting session.  That
     array contains another array.  However, our API returns
     a single 1d array, so we flatten the 2d array that is
     returned into a single array. Note that usually a coin
     is melted at most once, and so we'll only run this
     loop once for 'session=0' in most cases.

     num_coins tracks the size of the 1d array we return,
     whilst 'i' and 'session' track the 2d array. */
  for (session=0;session<json_array_size (json); session++)
  {
    json_t *jsona;
    struct GNUNET_JSON_Specification spec[] = {
      GNUNET_JSON_spec_json ("new_coins", &jsona),
      GNUNET_JSON_spec_end()
    };

    if (GNUNET_OK !=
	GNUNET_JSON_parse (json_array_get (json,
                                           session),
                           spec,
                           NULL, NULL))
    {
      GNUNET_break_op (0);
      return GNUNET_SYSERR;
    }
    if (! json_is_array (jsona))
    {
      GNUNET_break_op (0);
      GNUNET_JSON_parse_free (spec);
      return GNUNET_SYSERR;
    }

    /* count all coins over all sessions */
    num_coins += json_array_size (jsona);
    GNUNET_JSON_parse_free (spec);
  }
  /* Now that we know how big the 1d array is, allocate
     and fill it. */
  {
    unsigned int off_coin; /* index into 1d array */
    unsigned int i;
    struct TALER_CoinSpendPrivateKeyP coin_privs[num_coins];
    struct TALER_DenominationSignature sigs[num_coins];
    struct TALER_DenominationPublicKey pubs[num_coins];

    memset (sigs, 0, sizeof (sigs));
    memset (pubs, 0, sizeof (pubs));
    off_coin = 0;
    for (session=0;session<json_array_size (json); session++)
    {
      json_t *jsona;
      struct TALER_TransferPublicKeyP trans_pub;
      struct TALER_EncryptedLinkSecretP secret_enc;
      struct GNUNET_JSON_Specification spec[] = {
	GNUNET_JSON_spec_json ("new_coins", &jsona),
	GNUNET_JSON_spec_fixed_auto ("transfer_pub", &trans_pub),
	GNUNET_JSON_spec_fixed_auto ("secret_enc", &secret_enc),
	GNUNET_JSON_spec_end()
      };

      if (GNUNET_OK !=
	  GNUNET_JSON_parse (json_array_get (json,
                                             session),
                             spec,
                             NULL, NULL))
      {
	GNUNET_break_op (0);
	return GNUNET_SYSERR;
      }
      if (! json_is_array (jsona))
      {
	GNUNET_break_op (0);
	GNUNET_JSON_parse_free (spec);
	return GNUNET_SYSERR;
      }

      /* decode all coins */
      for (i=0;i<json_array_size (jsona);i++)
      {
	if (GNUNET_OK !=
	    parse_refresh_link_coin (rlh,
				     json_array_get (jsona,
						     i),
				     &trans_pub,
				     &secret_enc,
				     &coin_privs[i+off_coin],
				     &sigs[i+off_coin],
				     &pubs[i+off_coin]))
	{
	  GNUNET_break_op (0);
	  break;
	}
      }
      /* check if we really got all, then invoke callback */
      off_coin += i;
      if (i != json_array_size (jsona))
      {
	GNUNET_break_op (0);
	ret = GNUNET_SYSERR;
	GNUNET_JSON_parse_free (spec);
	break;
      }
      GNUNET_JSON_parse_free (spec);
    } /* end of for (session) */

    if (off_coin == num_coins)
    {
      rlh->link_cb (rlh->link_cb_cls,
		    MHD_HTTP_OK,
		    num_coins,
		    coin_privs,
		    sigs,
		    pubs,
		    json);
      rlh->link_cb = NULL;
      ret = GNUNET_OK;
    }
    else
    {
      GNUNET_break_op (0);
      ret = GNUNET_SYSERR;
    }

    /* clean up */
    for (i=0;i<off_coin;i++)
    {
      if (NULL != sigs[i].rsa_signature)
        GNUNET_CRYPTO_rsa_signature_free (sigs[i].rsa_signature);
      if (NULL != pubs[i].rsa_public_key)
        GNUNET_CRYPTO_rsa_public_key_free (pubs[i].rsa_public_key);
    }
  }
  return ret;
}


/**
 * Function called when we're done processing the
 * HTTP /refresh/link request.
 *
 * @param cls the `struct TALER_EXCHANGE_RefreshLinkHandle`
 * @param eh the curl request handle
 */
static void
handle_refresh_link_finished (void *cls,
                              CURL *eh)
{
  struct TALER_EXCHANGE_RefreshLinkHandle *rlh = cls;
  long response_code;
  json_t *json;

  rlh->job = NULL;
  json = MAC_download_get_result (&rlh->db,
                                  eh,
                                  &response_code);
  switch (response_code)
  {
  case 0:
    break;
  case MHD_HTTP_OK:
    if (GNUNET_OK !=
        parse_refresh_link_ok (rlh,
                               json))
    {
      GNUNET_break_op (0);
      response_code = 0;
    }
    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_NOT_FOUND:
    /* Nothing really to verify, exchange says this coin was not melted; 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 (NULL != rlh->link_cb)
    rlh->link_cb (rlh->link_cb_cls,
                  response_code,
                  0, NULL, NULL, NULL,
                  json);
  json_decref (json);
  TALER_EXCHANGE_refresh_link_cancel (rlh);
}


/**
 * Submit a link request to the exchange and get the exchange's response.
 *
 * This API is typically not used by anyone, it is more a threat
 * against those trying to receive a funds transfer by abusing the
 * /refresh protocol.
 *
 * @param exchange the exchange handle; the exchange must be ready to operate
 * @param coin_priv private key to request link data for
 * @param link_cb the callback to call with the useful result of the
 *        refresh operation the @a coin_priv was involved in (if any)
 * @param link_cb_cls closure for @a link_cb
 * @return a handle for this request
 */
struct TALER_EXCHANGE_RefreshLinkHandle *
TALER_EXCHANGE_refresh_link (struct TALER_EXCHANGE_Handle *exchange,
                         const struct TALER_CoinSpendPrivateKeyP *coin_priv,
                         TALER_EXCHANGE_RefreshLinkCallback link_cb,
                         void *link_cb_cls)
{
  struct TALER_EXCHANGE_RefreshLinkHandle *rlh;
  CURL *eh;
  struct TALER_EXCHANGE_Context *ctx;
  struct TALER_CoinSpendPublicKeyP coin_pub;
  char *pub_str;
  char *arg_str;

  if (GNUNET_YES !=
      MAH_handle_is_ready (exchange))
  {
    GNUNET_break (0);
    return NULL;
  }

  GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv->eddsa_priv,
                                      &coin_pub.eddsa_pub);
  pub_str = GNUNET_STRINGS_data_to_string_alloc (&coin_pub,
                                                 sizeof (struct TALER_CoinSpendPublicKeyP));
  GNUNET_asprintf (&arg_str,
                   "/refresh/link?coin_pub=%s",
                   pub_str);
  GNUNET_free (pub_str);

  rlh = GNUNET_new (struct TALER_EXCHANGE_RefreshLinkHandle);
  rlh->exchange = exchange;
  rlh->link_cb = link_cb;
  rlh->link_cb_cls = link_cb_cls;
  rlh->coin_priv = *coin_priv;
  rlh->url = MAH_path_to_url (exchange, arg_str);
  GNUNET_free (arg_str);

  eh = curl_easy_init ();
  GNUNET_assert (CURLE_OK ==
                 curl_easy_setopt (eh,
                                   CURLOPT_URL,
                                   rlh->url));
  GNUNET_assert (CURLE_OK ==
                 curl_easy_setopt (eh,
                                   CURLOPT_WRITEFUNCTION,
                                   &MAC_download_cb));
  GNUNET_assert (CURLE_OK ==
                 curl_easy_setopt (eh,
                                   CURLOPT_WRITEDATA,
                                   &rlh->db));
  ctx = MAH_handle_to_context (exchange);
  rlh->job = MAC_job_add (ctx,
                          eh,
                          GNUNET_YES,
                          &handle_refresh_link_finished,
                          rlh);
  return rlh;
}


/**
 * Cancel a refresh link request.  This function cannot be used
 * on a request handle if the callback was already invoked.
 *
 * @param rlh the refresh link handle
 */
void
TALER_EXCHANGE_refresh_link_cancel (struct TALER_EXCHANGE_RefreshLinkHandle *rlh)
{
  if (NULL != rlh->job)
  {
    MAC_job_cancel (rlh->job);
    rlh->job = NULL;
  }
  GNUNET_free_non_null (rlh->db.buf);
  GNUNET_free (rlh->url);
  GNUNET_free (rlh);
}


/* end of exchange_api_refresh_link.c */