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-rw-r--r--src/exchange-lib/exchange_api_context.c537
1 files changed, 537 insertions, 0 deletions
diff --git a/src/exchange-lib/exchange_api_context.c b/src/exchange-lib/exchange_api_context.c
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index 000000000..8d6746a17
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+++ b/src/exchange-lib/exchange_api_context.c
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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.c
+ * @brief Implementation of 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 "taler_exchange_service.h"
+#include "exchange_api_context.h"
+
+
+/**
+ * Log error related to CURL operations.
+ *
+ * @param type log level
+ * @param function which function failed to run
+ * @param code what was the curl error code
+ */
+#define CURL_STRERROR(type, function, code) \
+ GNUNET_log (type, \
+ "Curl function `%s' has failed at `%s:%d' with error: %s\n", \
+ function, __FILE__, __LINE__, curl_easy_strerror (code));
+
+/**
+ * Print JSON parsing related error information
+ */
+#define JSON_WARN(error) \
+ GNUNET_log (GNUNET_ERROR_TYPE_WARNING, \
+ "JSON parsing failed at %s:%u: %s (%s)\n", \
+ __FILE__, __LINE__, error.text, error.source)
+
+
+/**
+ * Failsafe flag. Raised if our constructor fails to initialize
+ * the Curl library.
+ */
+static int TALER_EXCHANGE_curl_fail;
+
+
+/**
+ * Jobs are CURL requests running within a `struct TALER_EXCHANGE_Context`.
+ */
+struct MAC_Job
+{
+
+ /**
+ * We keep jobs in a DLL.
+ */
+ struct MAC_Job *next;
+
+ /**
+ * We keep jobs in a DLL.
+ */
+ struct MAC_Job *prev;
+
+ /**
+ * Easy handle of the job.
+ */
+ CURL *easy_handle;
+
+ /**
+ * Context this job runs in.
+ */
+ struct TALER_EXCHANGE_Context *ctx;
+
+ /**
+ * Function to call upon completion.
+ */
+ MAC_JobCompletionCallback jcc;
+
+ /**
+ * Closure for @e jcc.
+ */
+ void *jcc_cls;
+
+};
+
+
+/**
+ * Context
+ */
+struct TALER_EXCHANGE_Context
+{
+ /**
+ * Curl multi handle
+ */
+ CURLM *multi;
+
+ /**
+ * Curl share handle
+ */
+ CURLSH *share;
+
+ /**
+ * We keep jobs in a DLL.
+ */
+ struct MAC_Job *jobs_head;
+
+ /**
+ * We keep jobs in a DLL.
+ */
+ struct MAC_Job *jobs_tail;
+
+ /**
+ * HTTP header "application/json", created once and used
+ * for all requests that need it.
+ */
+ struct curl_slist *json_header;
+
+};
+
+
+/**
+ * Initialise this library. This function should be called before using any of
+ * the following functions.
+ *
+ * @return library context
+ */
+struct TALER_EXCHANGE_Context *
+TALER_EXCHANGE_init ()
+{
+ struct TALER_EXCHANGE_Context *ctx;
+ CURLM *multi;
+ CURLSH *share;
+
+ if (TALER_EXCHANGE_curl_fail)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Curl was not initialised properly\n");
+ return NULL;
+ }
+ if (NULL == (multi = curl_multi_init ()))
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Failed to create a Curl multi handle\n");
+ return NULL;
+ }
+ if (NULL == (share = curl_share_init ()))
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Failed to create a Curl share handle\n");
+ return NULL;
+ }
+ ctx = GNUNET_new (struct TALER_EXCHANGE_Context);
+ ctx->multi = multi;
+ ctx->share = share;
+ GNUNET_assert (NULL != (ctx->json_header =
+ curl_slist_append (NULL,
+ "Content-Type: application/json")));
+ return ctx;
+}
+
+
+/**
+ * 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)
+{
+ struct MAC_Job *job;
+
+ if (GNUNET_YES == add_json)
+ GNUNET_assert (CURLE_OK ==
+ curl_easy_setopt (eh,
+ CURLOPT_HTTPHEADER,
+ ctx->json_header));
+
+ job = GNUNET_new (struct MAC_Job);
+ job->easy_handle = eh;
+ job->ctx = ctx;
+ job->jcc = jcc;
+ job->jcc_cls = jcc_cls;
+ GNUNET_CONTAINER_DLL_insert (ctx->jobs_head,
+ ctx->jobs_tail,
+ job);
+ GNUNET_assert (CURLE_OK ==
+ curl_easy_setopt (eh,
+ CURLOPT_PRIVATE,
+ job));
+ GNUNET_assert (CURLE_OK ==
+ curl_easy_setopt (eh,
+ CURLOPT_SHARE,
+ ctx->share));
+ GNUNET_assert (CURLM_OK ==
+ curl_multi_add_handle (ctx->multi,
+ eh));
+ return job;
+}
+
+
+/**
+ * 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)
+{
+ struct MAC_Job *job;
+
+ GNUNET_assert (CURLE_OK ==
+ curl_easy_getinfo (eh,
+ CURLINFO_PRIVATE,
+ (char **) &job));
+ return job->jcc_cls;
+}
+
+
+/**
+ * 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)
+{
+ struct TALER_EXCHANGE_Context *ctx = job->ctx;
+
+ GNUNET_CONTAINER_DLL_remove (ctx->jobs_head,
+ ctx->jobs_tail,
+ job);
+ GNUNET_assert (CURLM_OK ==
+ curl_multi_remove_handle (ctx->multi,
+ job->easy_handle));
+ curl_easy_cleanup (job->easy_handle);
+ GNUNET_free (job);
+}
+
+
+/**
+ * Run the main event loop for the Taler interaction.
+ *
+ * @param ctx the library context
+ */
+void
+TALER_EXCHANGE_perform (struct TALER_EXCHANGE_Context *ctx)
+{
+ CURLMsg *cmsg;
+ struct MAC_Job *job;
+ int n_running;
+ int n_completed;
+
+ (void) curl_multi_perform (ctx->multi,
+ &n_running);
+ while (NULL != (cmsg = curl_multi_info_read (ctx->multi,
+ &n_completed)))
+ {
+ /* Only documented return value is CURLMSG_DONE */
+ GNUNET_break (CURLMSG_DONE == cmsg->msg);
+ GNUNET_assert (CURLE_OK ==
+ curl_easy_getinfo (cmsg->easy_handle,
+ CURLINFO_PRIVATE,
+ (char **) &job));
+ GNUNET_assert (job->ctx == ctx);
+ job->jcc (job->jcc_cls,
+ cmsg->easy_handle);
+ MAC_job_cancel (job);
+ }
+}
+
+
+/**
+ * Obtain the information for a select() call to wait until
+ * #TALER_EXCHANGE_perform() is ready again. Note that calling
+ * any other TALER_EXCHANGE-API may also imply that the library
+ * is again ready for #TALER_EXCHANGE_perform().
+ *
+ * Basically, a client should use this API to prepare for select(),
+ * then block on select(), then call #TALER_EXCHANGE_perform() and then
+ * start again until the work with the context is done.
+ *
+ * This function will NOT zero out the sets and assumes that @a max_fd
+ * and @a timeout are already set to minimal applicable values. It is
+ * safe to give this API FD-sets and @a max_fd and @a timeout that are
+ * already initialized to some other descriptors that need to go into
+ * the select() call.
+ *
+ * @param ctx context to get the event loop information for
+ * @param read_fd_set will be set for any pending read operations
+ * @param write_fd_set will be set for any pending write operations
+ * @param except_fd_set is here because curl_multi_fdset() has this argument
+ * @param max_fd set to the highest FD included in any set;
+ * if the existing sets have no FDs in it, the initial
+ * value should be "-1". (Note that `max_fd + 1` will need
+ * to be passed to select().)
+ * @param timeout set to the timeout in milliseconds (!); -1 means
+ * no timeout (NULL, blocking forever is OK), 0 means to
+ * proceed immediately with #TALER_EXCHANGE_perform().
+ */
+void
+TALER_EXCHANGE_get_select_info (struct TALER_EXCHANGE_Context *ctx,
+ fd_set *read_fd_set,
+ fd_set *write_fd_set,
+ fd_set *except_fd_set,
+ int *max_fd,
+ long *timeout)
+{
+ long to;
+ int m;
+
+ m = -1;
+ GNUNET_assert (CURLM_OK ==
+ curl_multi_fdset (ctx->multi,
+ read_fd_set,
+ write_fd_set,
+ except_fd_set,
+ &m));
+ to = *timeout;
+ *max_fd = GNUNET_MAX (m, *max_fd);
+ GNUNET_assert (CURLM_OK ==
+ curl_multi_timeout (ctx->multi,
+ &to));
+
+ /* Only if what we got back from curl is smaller than what we
+ already had (-1 == infinity!), then update timeout */
+ if ( (to < *timeout) &&
+ (-1 != to) )
+ *timeout = to;
+ if ( (-1 == (*timeout)) &&
+ (NULL != ctx->jobs_head) )
+ *timeout = to;
+}
+
+
+/**
+ * Cleanup library initialisation resources. This function should be called
+ * after using this library to cleanup the resources occupied during library's
+ * initialisation.
+ *
+ * @param ctx the library context
+ */
+void
+TALER_EXCHANGE_fini (struct TALER_EXCHANGE_Context *ctx)
+{
+ /* all jobs must have been cancelled at this time, assert this */
+ GNUNET_assert (NULL == ctx->jobs_head);
+ curl_share_cleanup (ctx->share);
+ curl_multi_cleanup (ctx->multi);
+ curl_slist_free_all (ctx->json_header);
+ GNUNET_free (ctx);
+}
+
+
+/**
+ * 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.
+ *
+ * @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 KeysRequest`
+ * @return number of bytes processed from @a bufptr
+ */
+size_t
+MAC_download_cb (char *bufptr,
+ size_t size,
+ size_t nitems,
+ void *cls)
+{
+ struct MAC_DownloadBuffer *db = cls;
+ size_t msize;
+ void *buf;
+
+ if (0 == size * nitems)
+ {
+ /* Nothing (left) to do */
+ return 0;
+ }
+ msize = size * nitems;
+ if ( (msize + db->buf_size) >= GNUNET_MAX_MALLOC_CHECKED)
+ {
+ db->eno = ENOMEM;
+ return 0; /* signals an error to curl */
+ }
+ db->buf = GNUNET_realloc (db->buf,
+ db->buf_size + msize);
+ buf = db->buf + db->buf_size;
+ memcpy (buf, bufptr, msize);
+ db->buf_size += msize;
+ return msize;
+}
+
+
+/**
+ * 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)
+{
+ json_t *json;
+ json_error_t error;
+ char *ct;
+
+ if ( (CURLE_OK !=
+ curl_easy_getinfo (eh,
+ CURLINFO_CONTENT_TYPE,
+ &ct)) ||
+ (NULL == ct) ||
+ (0 != strcasecmp (ct,
+ "application/json")) )
+ {
+ /* No content type or explicitly not JSON, refuse to parse
+ (but keep response code) */
+ if (CURLE_OK !=
+ curl_easy_getinfo (eh,
+ CURLINFO_RESPONSE_CODE,
+ response_code))
+ {
+ /* unexpected error... */
+ GNUNET_break (0);
+ *response_code = 0;
+ }
+ return NULL;
+ }
+
+ json = NULL;
+ if (0 == db->eno)
+ {
+ json = json_loadb (db->buf,
+ db->buf_size,
+ JSON_REJECT_DUPLICATES | JSON_DISABLE_EOF_CHECK,
+ &error);
+ if (NULL == json)
+ {
+ JSON_WARN (error);
+ *response_code = 0;
+ }
+ }
+ GNUNET_free_non_null (db->buf);
+ db->buf = NULL;
+ db->buf_size = 0;
+ if (NULL != json)
+ {
+ if (CURLE_OK !=
+ curl_easy_getinfo (eh,
+ CURLINFO_RESPONSE_CODE,
+ response_code))
+ {
+ /* unexpected error... */
+ GNUNET_break (0);
+ *response_code = 0;
+ }
+ }
+ return json;
+}
+
+
+/**
+ * Initial global setup logic, specifically runs the Curl setup.
+ */
+__attribute__ ((constructor))
+void
+TALER_EXCHANGE_constructor__ (void)
+{
+ CURLcode ret;
+
+ if (CURLE_OK != (ret = curl_global_init (CURL_GLOBAL_DEFAULT)))
+ {
+ CURL_STRERROR (GNUNET_ERROR_TYPE_ERROR,
+ "curl_global_init",
+ ret);
+ TALER_EXCHANGE_curl_fail = 1;
+ }
+}
+
+
+/**
+ * Cleans up after us, specifically runs the Curl cleanup.
+ */
+__attribute__ ((destructor))
+void
+TALER_EXCHANGE_destructor__ (void)
+{
+ if (TALER_EXCHANGE_curl_fail)
+ return;
+ curl_global_cleanup ();
+}
+
+/* end of exchange_api_context.c */
generated by cgit v1.2.3 (git 2.26.2) at 2024-11-06 17:42:52 +0000