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/*
This file is part of TALER
Copyright (C) 2014, 2015 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_context.h
* @brief Internal interface to the context part of the exchange's HTTP API
* @author Sree Harsha Totakura <sreeharsha@totakura.in>
* @author Christian Grothoff
*/
#include "platform.h"
#include <curl/curl.h>
#include <gnunet/gnunet_util_lib.h>
#include "taler_exchange_service.h"
#include "taler_signatures.h"
/**
* Entry in the context's job queue.
*/
struct MAC_Job;
/**
* Function to call upon completion of a job.
*
* @param cls closure
* @param eh original easy handle (for inspection)
*/
typedef void
(*MAC_JobCompletionCallback)(void *cls,
CURL *eh);
/**
* Schedule a CURL request to be executed and call the given @a jcc
* upon its completion. Note that the context will make use of the
* CURLOPT_PRIVATE facility of the CURL @a eh. Applications can
* instead use #MAC_easy_to_closure to extract the @a jcc_cls argument
* from a valid @a eh afterwards.
*
* This function modifies the CURL handle to add the
* "Content-Type: application/json" header if @a add_json is set.
*
* @param ctx context to execute the job in
* @param eh curl easy handle for the request, will
* be executed AND cleaned up
* @param add_json add "application/json" content type header
* @param jcc callback to invoke upon completion
* @param jcc_cls closure for @a jcc
*/
struct MAC_Job *
MAC_job_add (struct TALER_EXCHANGE_Context *ctx,
CURL *eh,
int add_json,
MAC_JobCompletionCallback jcc,
void *jcc_cls);
/**
* Obtain the `jcc_cls` argument from an `eh` that was
* given to #MAC_job_add().
*
* @param eh easy handle that was used
* @return the `jcc_cls` that was given to #MAC_job_add().
*/
void *
MAC_easy_to_closure (CURL *eh);
/**
* Cancel a job. Must only be called before the job completion
* callback is called for the respective job.
*
* @param job job to cancel
*/
void
MAC_job_cancel (struct MAC_Job *job);
/**
* @brief Buffer data structure we use to buffer the HTTP download
* before giving it to the JSON parser.
*/
struct MAC_DownloadBuffer
{
/**
* Download buffer
*/
void *buf;
/**
* The size of the download buffer
*/
size_t buf_size;
/**
* Error code (based on libc errno) if we failed to download
* (i.e. response too large).
*/
int eno;
};
/**
* Callback used when downloading the reply to an HTTP request.
* Just appends all of the data to the `buf` in the
* `struct MAC_DownloadBuffer` for further processing. The size of
* the download is limited to #GNUNET_MAX_MALLOC_CHECKED, if
* the download exceeds this size, we abort with an error.
*
* Should be used by the various routines as the
* CURLOPT_WRITEFUNCTION. A `struct MAC_DownloadBuffer` needs to be
* passed to the CURLOPT_WRITEDATA.
*
* Afterwards, `eno` needs to be checked to ensure that the download
* completed correctly.
*
* @param bufptr data downloaded via HTTP
* @param size size of an item in @a bufptr
* @param nitems number of items in @a bufptr
* @param cls the `struct MAC_DownloadBuffer`
* @return number of bytes processed from @a bufptr
*/
size_t
MAC_download_cb (char *bufptr,
size_t size,
size_t nitems,
void *cls);
/**
* Obtain information about the final result about the
* HTTP download. If the download was successful, parses
* the JSON in the @a db and returns it. Also returns
* the HTTP @a response_code. If the download failed,
* the return value is NULL. The response code is set
* in any case, on download errors to zero.
*
* Calling this function also cleans up @a db.
*
* @param db download buffer
* @param eh CURL handle (to get the response code)
* @param[out] response_code set to the HTTP response code
* (or zero if we aborted the download, i.e.
* because the response was too big, or if
* the JSON we received was malformed).
* @return NULL if downloading a JSON reply failed
*/
json_t *
MAC_download_get_result (struct MAC_DownloadBuffer *db,
CURL *eh,
long *response_code);
/* end of exchange_api_context.h */
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