Line data Source code
1 : /*
2 : This file is part of TALER
3 : Copyright (C) 2025 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-reveal-melt.c
19 : * @brief Implementation of the /reveal-melt request
20 : * @author Özgür Kesim
21 : */
22 : #include <jansson.h>
23 : #include <microhttpd.h> /* just for HTTP status codes */
24 : #include <gnunet/gnunet_util_lib.h>
25 : #include <gnunet/gnunet_json_lib.h>
26 : #include <gnunet/gnunet_curl_lib.h>
27 : #include "taler/taler_json_lib.h"
28 : #include "exchange_api_common.h"
29 : #include "exchange_api_handle.h"
30 : #include "taler/taler_signatures.h"
31 : #include "exchange_api_curl_defaults.h"
32 : #include "exchange_api_refresh_common.h"
33 :
34 :
35 : /**
36 : * Handler for a running reveal-melt request
37 : */
38 : struct TALER_EXCHANGE_PostRevealMeltHandle
39 : {
40 : /**
41 : * The url for the request
42 : */
43 : char *request_url;
44 :
45 : /**
46 : * The exchange base URL.
47 : */
48 : char *exchange_url;
49 :
50 : /**
51 : * CURL handle for the request job.
52 : */
53 : struct GNUNET_CURL_Job *job;
54 :
55 : /**
56 : * Post Context
57 : */
58 : struct TALER_CURL_PostContext post_ctx;
59 :
60 : /**
61 : * Number of coins to expect
62 : */
63 : size_t num_expected_coins;
64 :
65 : /**
66 : * The input provided
67 : */
68 : const struct TALER_EXCHANGE_RevealMeltInput *reveal_input;
69 :
70 : /**
71 : * The melt data
72 : */
73 : struct MeltData md;
74 :
75 : /**
76 : * The curl context
77 : */
78 : struct GNUNET_CURL_Context *curl_ctx;
79 :
80 : /**
81 : * Callback to pass the result onto
82 : */
83 : TALER_EXCHANGE_PostRevealMeltCallback callback;
84 :
85 : /**
86 : * Closure for @e callback
87 : */
88 : void *callback_cls;
89 :
90 : };
91 :
92 : /**
93 : * We got a 200 OK response for the /reveal-melt operation.
94 : * Extract the signed blinded coins and return it to the caller.
95 : *
96 : * @param mrh operation handle
97 : * @param j_response reply from the exchange
98 : * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
99 : */
100 : static enum GNUNET_GenericReturnValue
101 14 : reveal_melt_ok (
102 : struct TALER_EXCHANGE_PostRevealMeltHandle *mrh,
103 : const json_t *j_response)
104 14 : {
105 14 : struct TALER_EXCHANGE_PostRevealMeltResponse response = {
106 : .hr.reply = j_response,
107 : .hr.http_status = MHD_HTTP_OK,
108 : };
109 14 : struct TALER_BlindedDenominationSignature blind_sigs[mrh->num_expected_coins];
110 : struct GNUNET_JSON_Specification spec[] = {
111 14 : TALER_JSON_spec_array_of_blinded_denom_sigs ("ev_sigs",
112 : mrh->num_expected_coins,
113 : blind_sigs),
114 14 : GNUNET_JSON_spec_end ()
115 : };
116 14 : if (GNUNET_OK !=
117 14 : GNUNET_JSON_parse (j_response,
118 : spec,
119 : NULL, NULL))
120 : {
121 0 : GNUNET_break_op (0);
122 0 : return GNUNET_SYSERR;
123 : }
124 :
125 14 : {
126 14 : struct TALER_EXCHANGE_RevealedCoinInfo coins[mrh->num_expected_coins];
127 :
128 : /* Reconstruct the coins and unblind the signatures */
129 70 : for (unsigned int i = 0; i<mrh->num_expected_coins; i++)
130 : {
131 56 : struct TALER_EXCHANGE_RevealedCoinInfo *rci = &coins[i];
132 56 : const struct FreshCoinData *fcd = &mrh->md.fcds[i];
133 : const struct TALER_DenominationPublicKey *pk;
134 : struct TALER_CoinSpendPublicKeyP coin_pub;
135 : struct TALER_CoinPubHashP coin_hash;
136 : struct TALER_FreshCoin coin;
137 : union GNUNET_CRYPTO_BlindingSecretP bks;
138 56 : const struct TALER_AgeCommitmentHashP *pah = NULL;
139 :
140 56 : rci->ps = fcd->ps[mrh->reveal_input->noreveal_index];
141 56 : rci->bks = fcd->bks[mrh->reveal_input->noreveal_index];
142 56 : rci->age_commitment_proof = NULL;
143 56 : pk = &fcd->fresh_pk;
144 56 : if (NULL != mrh->md.melted_coin.age_commitment_proof)
145 : {
146 : rci->age_commitment_proof
147 32 : = fcd->age_commitment_proofs[mrh->reveal_input->noreveal_index];
148 32 : TALER_age_commitment_hash (
149 32 : &rci->age_commitment_proof->commitment,
150 : &rci->h_age_commitment);
151 32 : pah = &rci->h_age_commitment;
152 : }
153 :
154 56 : TALER_planchet_setup_coin_priv (&rci->ps,
155 56 : &mrh->reveal_input->blinding_values[i],
156 : &rci->coin_priv);
157 56 : TALER_planchet_blinding_secret_create (&rci->ps,
158 56 : &mrh->reveal_input->blinding_values
159 56 : [i],
160 : &bks);
161 : /* needed to verify the signature, and we didn't store it earlier,
162 : hence recomputing it here... */
163 56 : GNUNET_CRYPTO_eddsa_key_get_public (&rci->coin_priv.eddsa_priv,
164 : &coin_pub.eddsa_pub);
165 56 : TALER_coin_pub_hash (&coin_pub,
166 : pah,
167 : &coin_hash);
168 56 : if (GNUNET_OK !=
169 56 : TALER_planchet_to_coin (pk,
170 56 : &blind_sigs[i],
171 : &bks,
172 56 : &rci->coin_priv,
173 : pah,
174 : &coin_hash,
175 56 : &mrh->reveal_input->blinding_values[i],
176 : &coin))
177 : {
178 0 : GNUNET_break_op (0);
179 0 : for (unsigned int k = 0; k < i; k++)
180 0 : TALER_denom_sig_free (&coins[k].sig);
181 0 : for (unsigned int k = 0; k < mrh->num_expected_coins; k++)
182 0 : TALER_blinded_denom_sig_free (&blind_sigs[k]);
183 0 : GNUNET_JSON_parse_free (spec);
184 0 : return GNUNET_SYSERR;
185 : }
186 56 : rci->sig = coin.sig;
187 : }
188 :
189 14 : response.details.ok.num_coins = mrh->num_expected_coins;
190 14 : response.details.ok.coins = coins;
191 14 : mrh->callback (mrh->callback_cls,
192 : &response);
193 : /* Make sure the callback isn't called again */
194 14 : mrh->callback = NULL;
195 : /* Free resources */
196 70 : for (size_t i = 0; i < mrh->num_expected_coins; i++)
197 : {
198 56 : struct TALER_EXCHANGE_RevealedCoinInfo *rci = &coins[i];
199 :
200 56 : TALER_denom_sig_free (&rci->sig);
201 : }
202 14 : GNUNET_JSON_parse_free (spec);
203 : }
204 :
205 14 : return GNUNET_OK;
206 : }
207 :
208 :
209 : /**
210 : * Function called when we're done processing the
211 : * HTTP /reveal-melt request.
212 : *
213 : * @param cls the `struct TALER_EXCHANGE_RevealMeltHandle`
214 : * @param response_code The HTTP response code
215 : * @param response response data
216 : */
217 : static void
218 14 : handle_reveal_melt_finished (
219 : void *cls,
220 : long response_code,
221 : const void *response)
222 : {
223 14 : struct TALER_EXCHANGE_PostRevealMeltHandle *mrh = cls;
224 14 : const json_t *j_response = response;
225 14 : struct TALER_EXCHANGE_PostRevealMeltResponse awr = {
226 : .hr.reply = j_response,
227 14 : .hr.http_status = (unsigned int) response_code
228 : };
229 :
230 14 : mrh->job = NULL;
231 14 : switch (response_code)
232 : {
233 0 : case 0:
234 0 : awr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
235 0 : break;
236 14 : case MHD_HTTP_OK:
237 : {
238 : enum GNUNET_GenericReturnValue ret;
239 :
240 14 : ret = reveal_melt_ok (mrh,
241 : j_response);
242 14 : if (GNUNET_OK != ret)
243 : {
244 0 : GNUNET_break_op (0);
245 0 : awr.hr.http_status = 0;
246 0 : awr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
247 0 : break;
248 : }
249 14 : GNUNET_assert (NULL == mrh->callback);
250 14 : TALER_EXCHANGE_post_reveal_melt_cancel (mrh);
251 14 : return;
252 : }
253 0 : case MHD_HTTP_BAD_REQUEST:
254 : /* This should never happen, either us or the exchange is buggy
255 : (or API version conflict); just pass JSON reply to the application */
256 0 : awr.hr.ec = TALER_JSON_get_error_code (j_response);
257 0 : awr.hr.hint = TALER_JSON_get_error_hint (j_response);
258 0 : break;
259 0 : case MHD_HTTP_NOT_FOUND:
260 : /* Nothing really to verify, the exchange basically just says
261 : that it doesn't know this age-melt commitment. */
262 0 : awr.hr.ec = TALER_JSON_get_error_code (j_response);
263 0 : awr.hr.hint = TALER_JSON_get_error_hint (j_response);
264 0 : break;
265 0 : case MHD_HTTP_CONFLICT:
266 : /* An age commitment for one of the coins did not fulfill
267 : * the required maximum age requirement of the corresponding
268 : * reserve.
269 : * Error code: TALER_EC_EXCHANGE_GENERIC_COIN_AGE_REQUIREMENT_FAILURE
270 : * or TALER_EC_EXCHANGE_AGE_WITHDRAW_REVEAL_INVALID_HASH.
271 : */
272 0 : awr.hr.ec = TALER_JSON_get_error_code (j_response);
273 0 : awr.hr.hint = TALER_JSON_get_error_hint (j_response);
274 0 : break;
275 0 : case MHD_HTTP_INTERNAL_SERVER_ERROR:
276 : /* Server had an internal issue; we should retry, but this API
277 : leaves this to the application */
278 0 : awr.hr.ec = TALER_JSON_get_error_code (j_response);
279 0 : awr.hr.hint = TALER_JSON_get_error_hint (j_response);
280 0 : break;
281 0 : default:
282 : /* unexpected response code */
283 0 : GNUNET_break_op (0);
284 0 : awr.hr.ec = TALER_JSON_get_error_code (j_response);
285 0 : awr.hr.hint = TALER_JSON_get_error_hint (j_response);
286 0 : GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
287 : "Unexpected response code %u/%d for exchange melt\n",
288 : (unsigned int) response_code,
289 : (int) awr.hr.ec);
290 0 : break;
291 : }
292 0 : mrh->callback (mrh->callback_cls,
293 : &awr);
294 0 : TALER_EXCHANGE_post_reveal_melt_cancel (mrh);
295 : }
296 :
297 :
298 : /**
299 : * Call /reveal-melt
300 : *
301 : * @param curl_ctx The context for CURL
302 : * @param mrh The handler
303 : */
304 : static void
305 14 : perform_protocol (
306 : struct GNUNET_CURL_Context *curl_ctx,
307 : struct TALER_EXCHANGE_PostRevealMeltHandle *mrh)
308 : {
309 : CURL *curlh;
310 : json_t *j_batch_seeds;
311 :
312 :
313 14 : j_batch_seeds = json_array ();
314 14 : GNUNET_assert (NULL != j_batch_seeds);
315 :
316 56 : for (uint8_t k = 0; k < TALER_CNC_KAPPA; k++)
317 : {
318 42 : if (mrh->reveal_input->noreveal_index == k)
319 14 : continue;
320 :
321 28 : GNUNET_assert (0 == json_array_append_new (
322 : j_batch_seeds,
323 : GNUNET_JSON_from_data_auto (
324 : &mrh->md.kappa_batch_seeds.tuple[k])));
325 : }
326 : {
327 : json_t *j_request_body;
328 :
329 14 : j_request_body = GNUNET_JSON_PACK (
330 : GNUNET_JSON_pack_data_auto ("rc",
331 : &mrh->md.rc),
332 : GNUNET_JSON_pack_array_steal ("batch_seeds",
333 : j_batch_seeds));
334 14 : GNUNET_assert (NULL != j_request_body);
335 :
336 14 : if (NULL != mrh->reveal_input->melt_input->melt_age_commitment_proof)
337 : {
338 8 : json_t *j_age = GNUNET_JSON_PACK (
339 : TALER_JSON_pack_age_commitment (
340 : "age_commitment",
341 : &mrh->reveal_input->melt_input->melt_age_commitment_proof->commitment)
342 : );
343 8 : GNUNET_assert (NULL != j_age);
344 8 : GNUNET_assert (0 ==
345 : json_object_update_new (j_request_body,
346 : j_age));
347 : }
348 14 : curlh = TALER_EXCHANGE_curl_easy_get_ (mrh->request_url);
349 14 : GNUNET_assert (NULL != curlh);
350 14 : GNUNET_assert (GNUNET_OK ==
351 : TALER_curl_easy_post (&mrh->post_ctx,
352 : curlh,
353 : j_request_body));
354 14 : json_decref (j_request_body);
355 : }
356 28 : mrh->job = GNUNET_CURL_job_add2 (
357 : curl_ctx,
358 : curlh,
359 14 : mrh->post_ctx.headers,
360 : &handle_reveal_melt_finished,
361 : mrh);
362 14 : if (NULL == mrh->job)
363 : {
364 0 : GNUNET_break (0);
365 0 : if (NULL != curlh)
366 0 : curl_easy_cleanup (curlh);
367 : /* caller must call _cancel to free mrh */
368 : }
369 14 : }
370 :
371 :
372 : struct TALER_EXCHANGE_PostRevealMeltHandle *
373 14 : TALER_EXCHANGE_post_reveal_melt_create (
374 : struct GNUNET_CURL_Context *curl_ctx,
375 : const char *exchange_url,
376 : const struct TALER_EXCHANGE_RevealMeltInput *reveal_melt_input)
377 : {
378 : struct TALER_EXCHANGE_PostRevealMeltHandle *mrh;
379 :
380 14 : if (reveal_melt_input->num_blinding_values !=
381 14 : reveal_melt_input->melt_input->num_fresh_denom_pubs)
382 : {
383 0 : GNUNET_break (0);
384 0 : return NULL;
385 : }
386 14 : mrh = GNUNET_new (struct TALER_EXCHANGE_PostRevealMeltHandle);
387 14 : mrh->reveal_input = reveal_melt_input;
388 14 : mrh->num_expected_coins = reveal_melt_input->melt_input->num_fresh_denom_pubs;
389 14 : mrh->curl_ctx = curl_ctx;
390 14 : mrh->exchange_url = GNUNET_strdup (exchange_url);
391 14 : if (GNUNET_OK !=
392 14 : TALER_EXCHANGE_get_melt_data (
393 14 : reveal_melt_input->rms,
394 14 : reveal_melt_input->melt_input,
395 14 : reveal_melt_input->blinding_seed,
396 14 : reveal_melt_input->blinding_values,
397 : &mrh->md))
398 : {
399 0 : GNUNET_break (0);
400 0 : GNUNET_free (mrh->exchange_url);
401 0 : GNUNET_free (mrh);
402 0 : return NULL;
403 : }
404 14 : return mrh;
405 : }
406 :
407 :
408 : enum TALER_ErrorCode
409 14 : TALER_EXCHANGE_post_reveal_melt_start (
410 : struct TALER_EXCHANGE_PostRevealMeltHandle *mrh,
411 : TALER_EXCHANGE_PostRevealMeltCallback reveal_cb,
412 : TALER_EXCHANGE_POST_REVEAL_MELT_RESULT_CLOSURE *reveal_cb_cls)
413 : {
414 14 : mrh->callback = reveal_cb;
415 14 : mrh->callback_cls = reveal_cb_cls;
416 14 : mrh->request_url = TALER_url_join (mrh->exchange_url,
417 : "reveal-melt",
418 : NULL);
419 14 : if (NULL == mrh->request_url)
420 : {
421 0 : GNUNET_break (0);
422 0 : return TALER_EC_GENERIC_CONFIGURATION_INVALID;
423 : }
424 14 : perform_protocol (mrh->curl_ctx,
425 : mrh);
426 14 : if (NULL == mrh->job)
427 : {
428 0 : GNUNET_break (0);
429 0 : return TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE;
430 : }
431 14 : return TALER_EC_NONE;
432 : }
433 :
434 :
435 : void
436 14 : TALER_EXCHANGE_post_reveal_melt_cancel (
437 : struct TALER_EXCHANGE_PostRevealMeltHandle *mrh)
438 : {
439 14 : if (NULL != mrh->job)
440 : {
441 0 : GNUNET_CURL_job_cancel (mrh->job);
442 0 : mrh->job = NULL;
443 : }
444 14 : TALER_curl_easy_post_finished (&mrh->post_ctx);
445 14 : TALER_EXCHANGE_free_melt_data (&mrh->md);
446 14 : GNUNET_free (mrh->request_url);
447 14 : GNUNET_free (mrh->exchange_url);
448 14 : GNUNET_free (mrh);
449 14 : }
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