Line data Source code
1 : /*
2 : This file is part of TALER
3 : Copyright (C) 2025-2026 Taler Systems SA
4 :
5 : TALER is free software; you can redistribute it and/or modify it under the
6 : terms of the GNU General Public License as published by the Free Software
7 : Foundation; either version 3, or (at your option) any later version.
8 :
9 : TALER is distributed in the hope that it will be useful, but WITHOUT ANY
10 : WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
11 : A PARTICULAR PURPOSE. See the GNU General Public License for more details.
12 :
13 : You should have received a copy of the GNU General Public License along with
14 : TALER; see the file COPYING. If not, see
15 : <http://www.gnu.org/licenses/>
16 : */
17 : /**
18 : * @file lib/exchange_api_post-blinding-prepare.c
19 : * @brief Implementation of /blinding-prepare requests
20 : * @author Özgür Kesim
21 : * @author Christian Grothoff
22 : */
23 :
24 : #include "taler/platform.h"
25 : #include <gnunet/gnunet_common.h>
26 : #include <jansson.h>
27 : #include <microhttpd.h> /* just for HTTP status codes */
28 : #include <gnunet/gnunet_util_lib.h>
29 : #include <gnunet/gnunet_json_lib.h>
30 : #include <gnunet/gnunet_curl_lib.h>
31 : #include <sys/wait.h>
32 : #include "taler/taler_curl_lib.h"
33 : #include "taler/taler_error_codes.h"
34 : #include "taler/taler_json_lib.h"
35 : #include "taler/taler_exchange_service.h"
36 : #include "exchange_api_common.h"
37 : #include "exchange_api_handle.h"
38 : #include "taler/taler_signatures.h"
39 : #include "exchange_api_curl_defaults.h"
40 : #include "taler/taler_util.h"
41 :
42 : /**
43 : * A /blinding-prepare request-handle
44 : */
45 : struct TALER_EXCHANGE_PostBlindingPrepareHandle
46 : {
47 : /**
48 : * Number of elements to prepare.
49 : */
50 : size_t num;
51 :
52 : /**
53 : * True, if this operation is for melting (or withdraw otherwise).
54 : */
55 : bool for_melt;
56 :
57 : /**
58 : * The seed for the batch of nonces.
59 : */
60 : const struct TALER_BlindingMasterSeedP *seed;
61 :
62 : /**
63 : * Copy of the nonce_keys array passed to _create.
64 : */
65 : struct TALER_EXCHANGE_NonceKey *nonce_keys;
66 :
67 : /**
68 : * The exchange base URL.
69 : */
70 : char *exchange_url;
71 :
72 : /**
73 : * The url for this request (built in _start).
74 : */
75 : char *url;
76 :
77 : /**
78 : * Context for curl.
79 : */
80 : struct GNUNET_CURL_Context *curl_ctx;
81 :
82 : /**
83 : * CURL handle for the request job.
84 : */
85 : struct GNUNET_CURL_Job *job;
86 :
87 : /**
88 : * Post Context
89 : */
90 : struct TALER_CURL_PostContext post_ctx;
91 :
92 : /**
93 : * Function to call with response results.
94 : */
95 : TALER_EXCHANGE_PostBlindingPrepareCallback callback;
96 :
97 : /**
98 : * Closure for @e callback.
99 : */
100 : void *callback_cls;
101 :
102 : };
103 :
104 :
105 : /**
106 : * We got a 200 OK response for the /blinding-prepare operation.
107 : * Extract the r_pub values and return them to the caller via the callback.
108 : *
109 : * @param handle operation handle
110 : * @param response response details
111 : * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
112 : */
113 : static enum GNUNET_GenericReturnValue
114 50 : blinding_prepare_ok (
115 : struct TALER_EXCHANGE_PostBlindingPrepareHandle *handle,
116 : struct TALER_EXCHANGE_PostBlindingPrepareResponse *response)
117 : {
118 : const json_t *j_r_pubs;
119 : const char *cipher;
120 : struct GNUNET_JSON_Specification spec[] = {
121 50 : GNUNET_JSON_spec_string ("cipher",
122 : &cipher),
123 50 : GNUNET_JSON_spec_array_const ("r_pubs",
124 : &j_r_pubs),
125 50 : GNUNET_JSON_spec_end ()
126 : };
127 :
128 50 : if (GNUNET_OK !=
129 50 : GNUNET_JSON_parse (response->hr.reply,
130 : spec,
131 : NULL, NULL))
132 : {
133 0 : GNUNET_break_op (0);
134 0 : return GNUNET_SYSERR;
135 : }
136 :
137 50 : if (strcmp ("CS", cipher))
138 : {
139 0 : GNUNET_break_op (0);
140 0 : return GNUNET_SYSERR;
141 : }
142 :
143 50 : if (json_array_size (j_r_pubs)
144 50 : != handle->num)
145 : {
146 0 : GNUNET_break_op (0);
147 0 : return GNUNET_SYSERR;
148 : }
149 :
150 50 : {
151 50 : size_t num = handle->num;
152 : const json_t *j_pair;
153 : size_t idx;
154 50 : struct TALER_ExchangeBlindingValues blinding_values[GNUNET_NZL (num)];
155 :
156 50 : memset (blinding_values,
157 : 0,
158 : sizeof(blinding_values));
159 :
160 148 : json_array_foreach (j_r_pubs, idx, j_pair) {
161 : struct GNUNET_CRYPTO_BlindingInputValues *bi =
162 98 : GNUNET_new (struct GNUNET_CRYPTO_BlindingInputValues);
163 98 : struct GNUNET_CRYPTO_CSPublicRPairP *csv = &bi->details.cs_values;
164 : struct GNUNET_JSON_Specification tuple[] = {
165 98 : GNUNET_JSON_spec_fixed (NULL,
166 98 : &csv->r_pub[0],
167 : sizeof(csv->r_pub[0])),
168 98 : GNUNET_JSON_spec_fixed (NULL,
169 98 : &csv->r_pub[1],
170 : sizeof(csv->r_pub[1])),
171 98 : GNUNET_JSON_spec_end ()
172 : };
173 : struct GNUNET_JSON_Specification jspec[] = {
174 98 : TALER_JSON_spec_tuple_of (NULL, tuple),
175 98 : GNUNET_JSON_spec_end ()
176 : };
177 : const char *err_msg;
178 : unsigned int err_line;
179 :
180 98 : if (GNUNET_OK !=
181 98 : GNUNET_JSON_parse (j_pair,
182 : jspec,
183 : &err_msg,
184 : &err_line))
185 : {
186 0 : GNUNET_break_op (0);
187 0 : GNUNET_free (bi);
188 0 : for (size_t i=0; i < idx; i++)
189 0 : TALER_denom_ewv_free (&blinding_values[i]);
190 0 : GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
191 : "Error while parsing response: in line %d: %s",
192 : err_line,
193 : err_msg);
194 0 : return GNUNET_SYSERR;
195 : }
196 :
197 98 : bi->cipher = GNUNET_CRYPTO_BSA_CS;
198 98 : bi->rc = 1;
199 98 : blinding_values[idx].blinding_inputs = bi;
200 : }
201 :
202 50 : response->details.ok.blinding_values = blinding_values;
203 50 : response->details.ok.num_blinding_values = num;
204 :
205 50 : handle->callback (
206 : handle->callback_cls,
207 : response);
208 :
209 148 : for (size_t i = 0; i < num; i++)
210 98 : TALER_denom_ewv_free (&blinding_values[i]);
211 : }
212 50 : return GNUNET_OK;
213 : }
214 :
215 :
216 : /**
217 : * Function called when we're done processing the HTTP /blinding-prepare
218 : * request.
219 : *
220 : * @param cls the `struct TALER_EXCHANGE_PostBlindingPrepareHandle`
221 : * @param response_code HTTP response code, 0 on error
222 : * @param response parsed JSON result, NULL on error
223 : */
224 : static void
225 50 : handle_blinding_prepare_finished (void *cls,
226 : long response_code,
227 : const void *response)
228 : {
229 50 : struct TALER_EXCHANGE_PostBlindingPrepareHandle *handle = cls;
230 50 : const json_t *j_response = response;
231 50 : struct TALER_EXCHANGE_PostBlindingPrepareResponse bpr = {
232 : .hr = {
233 : .reply = j_response,
234 50 : .http_status = (unsigned int) response_code
235 : },
236 : };
237 :
238 50 : handle->job = NULL;
239 :
240 50 : switch (response_code)
241 : {
242 0 : case 0:
243 0 : bpr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
244 0 : break;
245 :
246 50 : case MHD_HTTP_OK:
247 : {
248 50 : if (GNUNET_OK !=
249 50 : blinding_prepare_ok (handle,
250 : &bpr))
251 : {
252 0 : GNUNET_break_op (0);
253 0 : bpr.hr.http_status = 0;
254 0 : bpr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
255 0 : break;
256 : }
257 : }
258 50 : TALER_EXCHANGE_post_blinding_prepare_cancel (handle);
259 50 : return;
260 :
261 0 : case MHD_HTTP_BAD_REQUEST:
262 : /* This should never happen, either us or the exchange is buggy
263 : (or API version conflict); just pass JSON reply to the application */
264 0 : bpr.hr.ec = TALER_JSON_get_error_code (j_response);
265 0 : bpr.hr.hint = TALER_JSON_get_error_hint (j_response);
266 0 : break;
267 :
268 0 : case MHD_HTTP_NOT_FOUND:
269 : /* Nothing really to verify, the exchange basically just says
270 : that it doesn't know the /csr endpoint or denomination.
271 : Can happen if the exchange doesn't support Clause Schnorr.
272 : We should simply pass the JSON reply to the application. */
273 0 : bpr.hr.ec = TALER_JSON_get_error_code (j_response);
274 0 : bpr.hr.hint = TALER_JSON_get_error_hint (j_response);
275 0 : break;
276 :
277 0 : case MHD_HTTP_GONE:
278 : /* could happen if denomination was revoked */
279 0 : bpr.hr.ec = TALER_JSON_get_error_code (j_response);
280 0 : bpr.hr.hint = TALER_JSON_get_error_hint (j_response);
281 0 : break;
282 :
283 0 : case MHD_HTTP_INTERNAL_SERVER_ERROR:
284 : /* Server had an internal issue; we should retry, but this API
285 : leaves this to the application */
286 0 : bpr.hr.ec = TALER_JSON_get_error_code (j_response);
287 0 : bpr.hr.hint = TALER_JSON_get_error_hint (j_response);
288 0 : break;
289 :
290 0 : default:
291 : /* unexpected response code */
292 0 : GNUNET_break_op (0);
293 0 : bpr.hr.ec = TALER_JSON_get_error_code (j_response);
294 0 : bpr.hr.hint = TALER_JSON_get_error_hint (j_response);
295 0 : GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
296 : "Unexpected response code %u/%d for the blinding-prepare request\n",
297 : (unsigned int) response_code,
298 : (int) bpr.hr.ec);
299 0 : break;
300 :
301 : }
302 :
303 0 : handle->callback (handle->callback_cls,
304 : &bpr);
305 0 : handle->callback = NULL;
306 0 : TALER_EXCHANGE_post_blinding_prepare_cancel (handle);
307 : }
308 :
309 :
310 : struct TALER_EXCHANGE_PostBlindingPrepareHandle *
311 50 : TALER_EXCHANGE_post_blinding_prepare_create (
312 : struct GNUNET_CURL_Context *curl_ctx,
313 : const char *exchange_url,
314 : const struct TALER_BlindingMasterSeedP *seed,
315 : bool for_melt,
316 : size_t num,
317 : const struct TALER_EXCHANGE_NonceKey nonce_keys[static num])
318 50 : {
319 : struct TALER_EXCHANGE_PostBlindingPrepareHandle *bph;
320 :
321 50 : if (0 == num)
322 : {
323 0 : GNUNET_break (0);
324 0 : return NULL;
325 : }
326 148 : for (unsigned int i = 0; i < num; i++)
327 98 : if (GNUNET_CRYPTO_BSA_CS !=
328 98 : nonce_keys[i].pk->key.bsign_pub_key->cipher)
329 : {
330 0 : GNUNET_break (0);
331 0 : return NULL;
332 : }
333 50 : bph = GNUNET_new (struct TALER_EXCHANGE_PostBlindingPrepareHandle);
334 50 : bph->num = num;
335 50 : bph->for_melt = for_melt;
336 50 : bph->seed = seed;
337 50 : bph->curl_ctx = curl_ctx;
338 50 : bph->exchange_url = GNUNET_strdup (exchange_url);
339 50 : bph->nonce_keys = GNUNET_new_array (num,
340 : struct TALER_EXCHANGE_NonceKey);
341 50 : memcpy (bph->nonce_keys,
342 : nonce_keys,
343 : num * sizeof (struct TALER_EXCHANGE_NonceKey));
344 50 : return bph;
345 : }
346 :
347 :
348 : enum TALER_ErrorCode
349 50 : TALER_EXCHANGE_post_blinding_prepare_start (
350 : struct TALER_EXCHANGE_PostBlindingPrepareHandle *bph,
351 : TALER_EXCHANGE_PostBlindingPrepareCallback cb,
352 : TALER_EXCHANGE_POST_BLINDING_PREPARE_RESULT_CLOSURE *cb_cls)
353 : {
354 : CURL *eh;
355 : json_t *j_nks;
356 : json_t *j_request;
357 :
358 50 : bph->callback = cb;
359 50 : bph->callback_cls = cb_cls;
360 :
361 50 : bph->url = TALER_url_join (bph->exchange_url,
362 : "blinding-prepare",
363 : NULL);
364 50 : if (NULL == bph->url)
365 : {
366 0 : GNUNET_break (0);
367 0 : return TALER_EC_GENERIC_CONFIGURATION_INVALID;
368 : }
369 :
370 50 : j_request = GNUNET_JSON_PACK (
371 : GNUNET_JSON_pack_string ("cipher",
372 : "CS"),
373 : GNUNET_JSON_pack_string ("operation",
374 : bph->for_melt ? "melt" : "withdraw"),
375 : GNUNET_JSON_pack_data_auto ("seed",
376 : bph->seed));
377 50 : GNUNET_assert (NULL != j_request);
378 :
379 50 : j_nks = json_array ();
380 50 : GNUNET_assert (NULL != j_nks);
381 :
382 148 : for (size_t i = 0; i < bph->num; i++)
383 : {
384 98 : const struct TALER_EXCHANGE_NonceKey *nk = &bph->nonce_keys[i];
385 98 : json_t *j_entry = GNUNET_JSON_PACK (
386 : GNUNET_JSON_pack_uint64 ("coin_offset",
387 : nk->cnc_num),
388 : GNUNET_JSON_pack_data_auto ("denom_pub_hash",
389 : &nk->pk->h_key));
390 :
391 98 : GNUNET_assert (NULL != j_entry);
392 98 : GNUNET_assert (0 ==
393 : json_array_append_new (j_nks,
394 : j_entry));
395 : }
396 50 : GNUNET_assert (0 ==
397 : json_object_set_new (j_request,
398 : "nks",
399 : j_nks));
400 :
401 50 : eh = TALER_EXCHANGE_curl_easy_get_ (bph->url);
402 100 : if ( (NULL == eh) ||
403 : (GNUNET_OK !=
404 50 : TALER_curl_easy_post (&bph->post_ctx,
405 : eh,
406 : j_request)))
407 : {
408 0 : GNUNET_break (0);
409 0 : if (NULL != eh)
410 0 : curl_easy_cleanup (eh);
411 0 : json_decref (j_request);
412 0 : return TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE;
413 : }
414 :
415 50 : json_decref (j_request);
416 100 : bph->job = GNUNET_CURL_job_add2 (bph->curl_ctx,
417 : eh,
418 50 : bph->post_ctx.headers,
419 : &handle_blinding_prepare_finished,
420 : bph);
421 50 : if (NULL == bph->job)
422 : {
423 0 : GNUNET_break (0);
424 0 : return TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE;
425 : }
426 50 : return TALER_EC_NONE;
427 : }
428 :
429 :
430 : void
431 125 : TALER_EXCHANGE_post_blinding_prepare_cancel (
432 : struct TALER_EXCHANGE_PostBlindingPrepareHandle *bph)
433 : {
434 125 : if (NULL == bph)
435 75 : return;
436 50 : if (NULL != bph->job)
437 : {
438 0 : GNUNET_CURL_job_cancel (bph->job);
439 0 : bph->job = NULL;
440 : }
441 50 : GNUNET_free (bph->url);
442 50 : GNUNET_free (bph->exchange_url);
443 50 : GNUNET_free (bph->nonce_keys);
444 50 : TALER_curl_easy_post_finished (&bph->post_ctx);
445 50 : GNUNET_free (bph);
446 : }
447 :
448 :
449 : /* end of lib/exchange_api_post-blinding-prepare.c */
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