summaryrefslogtreecommitdiff
path: root/api-merchant.rst
blob: a6b28096dcf30733a207ada42f33980d2a872d30 (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
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
..
  This file is part of GNU TALER.
  Copyright (C) 2014, 2015, 2016 INRIA

  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 2.1, 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 Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License along with
  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>

  @author Marcello Stanisci
  @author Florian Dold
  @author Christian Grothoff

.. _merchant-api:

============
Merchant API
============

Before reading the API reference documentation, see the :ref:`merchant architecture<merchant-arch>` and :ref:`payprot`

---------------------
The Frontend HTTP API
---------------------

.. http:get:: contract_url

  Triggers the contract generation. Note that the URL may differ between
  merchants.

  **Request:**

  The request depends entirely on the merchant implementation.

  **Response**

  :status 200 OK: The request was successful.  The body contains an :ref:`Offer <contract>`.
  :status 400 Bad Request: Request not understood.
  :status 500 Internal Server Error:
    In most cases, some error occurred while the backend was generating the
    contract. For example, it failed to store it into its database.

.. _pay:
.. http:post:: pay_url


  Send the deposit permission to the merchant. The client should POST a `DepositPermission`_
  object.

  .. _DepositPermission:
  .. code-block:: tsref

    interface DepositPermission {
      // the hashed `wire details <wireformats>`_ of this merchant.
      // The wallet takes this value as-is from the contract 
      H_wire: HashCode;

      // `base32`_ encoded `TALER_ContractPS`_. The wallet can choose whether
      // to take this value obtained from the field `h_contract`,
      // or regenerating one starting from the values it gets within the contract
      H_contract: HashCode;

      // a 53-bit number corresponding to the contract being agreed on
      transaction_id: number;

      // total amount being paid as per the contract (the sum of the amounts from the `coins` may be larger to cover deposit fees not covered by the merchant)
      total_amount: Amount;

      // maximum fees merchant agreed to cover as per the contract
      max_fee: Amount;

      // The `merchant instance <instances-lab>`_ which is going to receive the final wire transfer.
      instance: string;

      // Signature of `TALER_ContractPS`_
      merchant_sig: EddsaSignature;

      // a timestamp of this deposit permission. It equals just the contract's timestamp
      timestamp: Timestamp;

      // Deadline for the customer to be refunded for this purchase
      refund_deadline: Timestamp;

      // Deadline for the customer to pay for this purchase. Note that is up to the frontend
      // to make sure that this value matches the one the backend signed over when the contract
      // was generated. The frontend should never verify if the payment is still on time,
      // because when payments are replayed it is expxectable that this deadline is expired,
      // and only the backend can detect if a payment is a reply or not. 
      pay_deadline: Timestamp;

      // the chosen exchange's base URL
      exchange: string;

      // the coins used to sign the contract
      coins: DepositedCoin[];

    }

  .. _`tsref-type-DepositedCoin`:

  .. code-block:: tsref

    interface DepositedCoin {
      // the amount this coin is paying for
      amount: Amount;

      // coin's public key
      coin_pub: RsaPublicKey;

      // denomination key
      denom_pub: RsaPublicKey;

      // exchange's signature over this `coin's public key <eddsa-coin-pub>`_
      ub_sig: RsaSignature;

      // Signature of `TALER_DepositRequestPS`_
      coin_sig: EddsaSignature;
    }

  **Success Response:**

  :status 301 Redirection: the merchant should redirect the client to his fullfillment page, where the good outcome of the purchase must be shown to the user.

  **Failure Responses:**

  The error codes and data sent to the wallet are a mere copy of those gotten from the exchange when attempting to pay. The section about :ref:`deposit <deposit>` explains them in detail.


.. http:post:: fulfillment_url

  Returns a cooperative merchant page (called the execution page) that will
  send the ``taler-execute-payment`` to the wallet and react to failure or
  success of the actual payment. ``fulfillment_url`` is included in the `contract`_.
  Furthermore, :ref:`payprot` documents the payment protocol between wallets and
  merchants.

  The wallet will inject an ``XMLHttpRequest`` request to the merchant's
  ``$pay_url`` in the context of the execution page.  This mechanism is
  necessary since the request to ``$pay_url`` must be made from the merchant's
  origin domain in order to preserve information (e.g. cookies, origin header).

.. http:get:: /history

  Return a list of fulfilled contracts.  Typically used by backoffice interfaces.

  **Request**

  :query days: a number indicating that we request contracts from now up to `days` days ago.

  **Response**
  
  :status 200 OK: The response is a JSON array of  `TransactionHistory`_.

.. http:get:: /map

  Takes a hashcode and return the related contract.  Typically used by backoffice interfaces.

  **Request**

  :query h_contract: hashcode of the contract we want to retrieve.

  **Return**

  :status 200 OK:
    The body contains a `contract`_ corresponding to `h_contract`.

  :status 404 Not Found:
    There is no contract corresponding to `h_contract`.


------------------------------
The Merchant Backend HTTP API
------------------------------

The following API are made available by the merchant's `backend` to the merchant's `frontend`.

.. http:post:: /contract

  Ask the backend to add some missing (mostly related to cryptography) information to the contract.

  **Request:**

.. _proposition:

  The `proposition` that is to be sent from the frontend is a :ref:`Contract <contract>` object
  **without** the fields:

  * `exchanges`
  * `auditors`
  * `H_wire`
  * `merchant_pub`

  The frontend may or may not provide a `instance` field in the proposition, depending on its logic.
  The ``default`` instance will be used if no `instance` field is found by the backend.

  **Response**

  :status 200 OK:
    The backend has successfully created the contract.  It responds with an :ref:`offer <offer>`. On success, the `frontend` should pass this response verbatim to the wallet.

  :status 403 Forbidden:
    The frontend used the same transaction ID twice.  This is only allowed if the response from the backend was lost ("instant" replay), but to assure that frontends usually create fresh transaction IDs this is forbidden if the contract was already paid.  So attempting to have the backend sign a contract for a contract that was already paid by a wallet (and thus was generated by the frontend a "long" time ago), is forbidden and results in this error.  Frontends must make sure that they increment the transaction ID properly and persist the largest value used so far.

.. http:post:: /pay

  Asks the `backend` to execute the transaction with the exchange and deposit the coins.

  **Request:**

  The `frontend` passes the :ref:`deposit permission <DepositPermission>`
  received from the wallet, and optionally adding a field named `wire_transfer_deadline`,
  indicating a deadline by which he would expect to receive the bank transfer
  for this deal.  Note that the `wire_transfer_deadline` must be after the `refund_deadline`.
  The backend calculates the `wire_transfer_deadline` by adding the `wire_transfer_delay`
  value found in the configuration to the current time.

  **Response:**

  :status 200 OK:
    The exchange accepted all of the coins. The body is a `PaymentResponse`_.
    The `frontend` should now fullfill the contract.
  :status 412 Precondition Failed:
    The given exchange is not acceptable for this merchant, as it is not in the
    list of accepted exchanges and not audited by an approved auditor.
  :status 403 Forbidden:
    The exchange rejected the payment because a coin was already spent before.
    The response will include the `coin_pub` for which the payment failed,
    in addition to the response from the exchange to the `/deposit` request.

  The `backend` will return verbatim the error codes received from the exchange's
  :ref:`deposit <deposit>` API.  If the wallet made a mistake, like by
  double-spending for example, the `frontend` should pass the reply verbatim to
  the browser/wallet. This should be the expected case, as the `frontend`
  cannot really make mistakes; the only reasonable exception is if the
  `backend` is unavailable, in which case the customer might appreciate some
  reassurance that the merchant is working on getting his systems back online.

  .. _PaymentResponse:
  .. code-block:: tsref

    interface PaymentResponse {
      // Signature of `TALER_PaymentResponsePS`_
      merchant_sig: EddsaSignature;

      // Contract's hash being signed over
      h_contract: HashCode;
    }

.. http:get:: /track/transfer

  Provides deposits associated with a given wire transfer.

  **Request:**

  :query wtid: raw wire transfer identifier identifying the wire transfer (a base32-encoded value)
  :query exchange: base URI of the exchange that made the wire transfer
  :query instance: (optional) identificative token of the merchant :ref:`instance <instances-lab>` which is being tracked.

  **Response:**

  :status 200 OK:
    The wire transfer is known to the exchange, details about it follow in the body.
    The body of the response is a :ref:`TrackTransferResponse <TrackTransferResponse>`.  Note that
    the similarity to the response given by the exchange for a /track/transfer
    is completely intended.

  :status 404 Not Found:
    The wire transfer identifier is unknown to the exchange.

  :status 424 Failed Dependency: The exchange provided conflicting information about the transfer. Namely,
    there is at least one deposit among the deposits aggregated by `wtid` that accounts for a coin whose
    details don't match the details stored in merchant's database about the same keyed coin.
    The response body contains the `TrackTransferConflictDetails`_.


  **Details:**

  .. _tsref-type-TrackTransferConflictDetails:
  .. _TrackTransferConflictDetails:
  .. code-block:: tsref

    interface TrackTransferConflictDetails {
      // Numerical `error code <error-codes>`_
      code: number;

      // Text describing the issue for humans.
      hint: String;

      // A /deposit response matching `coin_pub` showing that the
      // exchange accepted `coin_pub` for `amount_with_fee`.
      exchange_deposit_proof: DepositSuccess;

      // Offset in the `exchange_transfer_proof` where the
      // exchange's response fails to match the `exchange_deposit_proof`.
      conflict_offset: number;

      // The response from the exchange which tells us when the
      // coin was returned to us, except that it does not match
      // the expected value of the coin.
      exchange_transfer_proof: TrackTransferResponse;

      // Public key of the coin for which we have conflicting information.
      coin_pub: EddsaPublicKey;

      // Merchant transaction in which `coin_pub` was involved for which
      // we have conflicting information.
      transaction_id: number;

      // Expected value of the coin.
      amount_with_fee: Amount;

      // Expected deposit fee of the coin.
      deposit_fee: Amount;

    }


.. http:get:: /track/transaction

  Provide the wire transfer identifier associated with an (existing) deposit operation.

  **Request:**

  :query id: ID of the transaction we want to trace (an integer)
  :query instance: identificative token for the merchant instance which is to be tracked (optional). See :ref:`instances-lab`. This information is needed because the request has to be signed by the merchant, thus we need to pick the instance's private key.

  **Response:**

  :status 200 OK:
    The deposit has been executed by the exchange and we have a wire transfer identifier.
     The response body is a JSON array of `TransactionWireTransfer`_ objects.


  :status 202 Accepted:
    The deposit request has been accepted for processing, but was not yet
    executed.  Hence the exchange does not yet have a wire transfer identifier.
    The merchant should come back later and ask again.
    The response body is a :ref:`TrackTransactionAcceptedResponse <TrackTransactionAcceptedResponse>`.  Note that
    the similarity to the response given by the exchange for a /track/transaction
    is completely intended.

  :status 404 Not Found: The transaction is unknown to the backend.

  :status 424 Failed Dependency:
    The exchange previously claimed that a deposit was not included in a wire transfer, and now claims that it is.  This means that the exchange is dishonest.  The response contains the cryptographic proof that the exchange is misbehaving in the form of a `TransactionConflictProof`_.

  **Details:**

  .. _tsref-type-TransactionWireTransfer:
  .. _TransactionWireTransfer:
  .. code-block:: tsref

    interface TransactionWireTransfer {

      // Responsible exchange
      exchange_uri: string;

      // 32-byte wire transfer identifier
      wtid: Base32;

      // execution time of the wire transfer
      execution_time: Timestamp;

      // Array of data about coins
      coins: CoinWireTransfer[];
    }

  .. _tsref-type-CoinWireTransfer:
  .. _CoinWireTransfer:
  .. code-block:: tsref

    interface CoinWireTransfer {
      // public key of the coin that was deposited
      coin_pub: EddsaPublicKey;

      // Amount the coin was worth (including deposit fee)
      amount_with_fee: Amount;

      // Deposit fee retained by the exchange for the coin
      deposit_fee: Amount;
    }

  .. _TransactionConflictProof:
  .. _tsref-type-TransactionConflictProof:
  .. code-block:: tsref

    interface TransactionConflictProof {
      // Numerical `error code <error-codes>`_
      code: number;

      // Human-readable error description
      hint: string;

      // A claim by the exchange about the transactions associated
      // with a given wire transfer; it does not list the
      // transaction that `transaction_tracking_claim` says is part
      // of the aggregate.  This is
      // a `/track/transfer` response from the exchange.
      wtid_tracking_claim: TrackTransferResponse;

      // The current claim by the exchange that the given
      // transaction is included in the above WTID.
      // (A response from `/track/transaction`).
      transaction_tracking_claim: TrackTransactionResponse;

      // Public key of the coin for which we got conflicting information.
      coin_pub: CoinPublicKey;

    }


.. http:post:: /map/in

  Store a pair formed by a plain contract and its hashcode into the database.

  **Request**

  The frontend passes a `MapRequest`_ object.

  **Response**

  :status 200 OK:
    The data has been successfully stored.

  :status 422 Unprocessable Entity:
    The hashcode provided by the frontend does not match the contract.

.. _MapRequest:
.. _tsref-type-MapRequest:
.. code-block:: tsref

  interface MapRequest {

    // Plain contract to be stored
    contract: Contract;

    // contract's hashcode. We require this value from the frontend
    // as an additional check on data integrity.
    h_contract: HashCode;
  }


.. http:get:: /map/out

  Retrieve a contract, given its hashcode.

  **Request**

  :query h_contract: hashcode of the contract to retrieve.

  **Response**

  :status 200 OK:
    The body contains a `contract`_ corresponding to `h_contract`.

  :status 404 Not Found:
    There is no contract corresponding to `h_contract` into the database.

.. http:get:: /history

  Returns transactions up to some point in the past

  **Request**

  :query date: only transactions *jounger* than this parameter will be returned. It's a timestamp, given in seconds.

  **Response**

  :status 200 OK: The response is a JSON `array` of  `TransactionHistory`_.

  .. _tsref-type-TransactionHistory:
  .. _TransactionHistory:
  .. code-block:: tsref

    interface TransactionHistory {
      // transaction id
      transaction_id: number;

      // Hashcode of the relevant contract
      h_contract: HashCode;

      // Exchange's base URL
      exchange: string;

      // Transaction's timestamp
      timestamp: Timestamp;

      // Price payed for this transaction
      total_amount: Amount;
    }

.. _contract:

------------------
Offer and Contract
------------------

An `offer` is a wrapper around a contract with some additional information
that is legally non-binding:

  .. _tsref-type-Offer:
  .. code-block:: tsref
    :name: offer

    interface Offer {
      // The actual contract
      contract: Contract;

      // Contract's hash, provided as a convenience.  All components that do
      // not fully trust the merchant must verify this field.
      H_contract: HashCode ;

      // Signature over the hashcode of `contract` made by the merchant.
      merchant_sig: EddsaSignature;
    }

.. note::
  When the contract is signed by the merchant or the wallet, the
  signature is made over the hash of the JSON text, as the contract may
  be confidential between merchant and customer and should not be
  exposed to the exchange.  The hashcode is generated by hashing the
  encoding of the contract's JSON obtained by using the flags
  ``JSON_COMPACT | JSON_PRESERVE_ORDER``, as described in the `libjansson
  documentation
  <https://jansson.readthedocs.org/en/2.7/apiref.html?highlight=json_dumps#c.json_dumps>`_.

The `contract` must have the following structure:

  .. _tsref-type-Contract:
  .. code-block:: tsref

    interface Contract {
      // Human-readable description of the whole purchase
      // NOTE: still not implemented
      summary: string;

      // Total price for the transaction.
      // The exchange will subtract deposit fees from that amount
      // before transfering it to the merchant.
      amount: Amount;

      // Optional identifier chosen by the merchant,
      // which allows the wallet to detect if it is buying
      // a contract where it already has paid for the same
      // product instance. NOTE: this information is mainly
      // needed when the customer visits a shared fulfillment
      // URL about a product they already paid for, so that
      // the wallet can reuse the same coins used in the first
      // place.
      repurchase_correlation_id?: string;

      // URL that the wallet will navigate to after the customer
      // confirmed purchasing the contract.  Responsible for
      // doing the actual payment and making available the product (if digital)
      // or displaying a confirmation.
      // The placeholder ${H_contract} will be replaced
      // with the contract hash by wallets before navigating
      // to the fulfillment URL.
      fulfillment_url: string;

      // Maximum total deposit fee accepted by the merchant for this contract
      max_fee: Amount;

      // 53-bit number chosen by the merchant to uniquely identify the contract.
      transaction_id: number;

      // List of products that are part of the purchase (see `below <Product>`_)
      products: Product[];

      // Time when this contract was generated
      timestamp: Timestamp;

      // After this deadline has passed, no refunds will be accepted.
      refund_deadline: Timestamp;

      // After this deadline, the merchant won't accept payments for the contact
      expiry: Timestamp;

      // Merchant's public key used to sign this contract; this information is typically added by the backend
      // Note that this can be an ephemeral key.
      merchant_pub: EddsaPublicKey;

      // More info about the merchant, see below
      merchant: Merchant;

      // Which instance is participating in this contract. See `Merchant Instances <instances-lab>`_.
      // This field is optional, as the "default" instance is not forced to provide any `instance` identificator.
      instance: string;

      // The hash of the merchant instance's wire details.
      H_wire: HashCode;

      // Any exchanges audited by these auditors are accepted by the merchant.
      auditors: Auditor[];

      // Exchanges that the merchant accepts even if it does not accept any auditors that audit them.
      exchanges: Exchange[];

      // Map from labels to locations
      locations: { [label: string]: [location: Location], ... };
    }

  The wallet must select a exchange that either the mechant accepts directly by listing it in the exchanges arry, or for which the merchant accepts an auditor that audits that exchange by listing it in the auditors array.

  The `product` object describes the product being purchased from the merchant. It has the following structure:

  .. _Product:
  .. _tsref-type-Product:
  .. code-block:: tsref

    interface Product {
      // Human-readable product description.
      description: string;

      // The quantity of the product to deliver to the customer (optional, if applicable)
      quantity?: number;

      // The price of the product; this is the total price for the amount specified by `quantity`
      price: Amount;

      // merchant's 53-bit internal identification number for the product (optional)
      product_id?: number;

      // a list of objects indicating a `taxname` and its amount. Again, italics denotes the object field's name.
      taxes?: any[];

      // time indicating when this product should be delivered
      delivery_date: Timestamp;

      // where to deliver this product. This may be an URI for online delivery
      // (i.e. `http://example.com/download` or `mailto:customer@example.com`),
      // or a location label defined inside the proposition's `locations`.
      // The presence of a colon (`:`) indicates the use of an URL.
      delivery_location: string;
    }

  .. _tsref-type-Merchant:
  .. code-block:: ts

    interface Merchant {
      // label for a location with the business address of the merchant
      address: string;

      // the merchant's legal name of business
      name: string;

      // label for a location that denotes the jurisdiction for disputes.
      // Some of the typical fields for a location (such as a street address) may be absent.
      jurisdiction: string;
    }


  .. _tsref-type-Location:
  .. _Location:
  .. code-block:: ts

    interface Location {
      country?: string;
      city?: string;
      state?: string;
      region?: string;
      province?: string;
      zip_code?: string;
      street?: string;
      street_number?: string;
    }

  .. _tsref-type-Auditor:
  .. code-block:: tsref

    interface Auditor {
      // official name
      name: string;

      // Auditor's public key
      auditor_pub: EddsaPublicKey;

      // Base URL of the auditor
      url: string;
    }

  .. _tsref-type-Exchange:
  .. code-block:: tsref

    interface Exchange {
      // the exchange's base URL
      url: string;

      // master public key of the exchange
      master_pub: EddsaPublicKey;
    }