replace exchange_api_context with libgnunetcurl

16 files changed, 189 insertions, 1093 deletions

diff --git a/src/exchange-lib/Makefile.am b/src/exchange-lib/Makefile.am
index d953a7a86..ea53623fb 100644
--- a/src/exchange-lib/Makefile.am
+++ b/src/exchange-lib/Makefile.am
@@ -15,7 +15,6 @@ libtalerexchange_la_LDFLAGS = \
 
 libtalerexchange_la_SOURCES = \
   exchange_api_common.c exchange_api_common.h \
-  exchange_api_context.c exchange_api_context.h \
   exchange_api_handle.c exchange_api_handle.h \
   exchange_api_admin.c \
   exchange_api_deposit.c \
@@ -29,6 +28,7 @@ libtalerexchange_la_SOURCES = \
 libtalerexchange_la_LIBADD = \
   $(top_builddir)/src/json/libtalerjson.la \
   $(top_builddir)/src/util/libtalerutil.la \
+  -lgnunetcurl \
   -lgnunetjson \
   -lgnunetutil \
   -ljansson \
@@ -57,6 +57,7 @@ test_exchange_api_LDADD = \
   $(LIBGCRYPT_LIBS) \
   $(top_builddir)/src/json/libtalerjson.la \
   $(top_builddir)/src/util/libtalerutil.la \
+  -lgnunetcurl \
   -lgnunetutil \
   -ljansson
 
diff --git a/src/exchange-lib/exchange_api_admin.c b/src/exchange-lib/exchange_api_admin.c
index 871a88a6b..06a39ffa4 100644
--- a/src/exchange-lib/exchange_api_admin.c
+++ b/src/exchange-lib/exchange_api_admin.c
@@ -25,9 +25,9 @@
 #include <microhttpd.h> /* just for HTTP status codes */
 #include <gnunet/gnunet_util_lib.h>
 #include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_json_lib.h"
 #include "taler_exchange_service.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 #include "taler_signatures.h"
 
@@ -56,7 +56,7 @@ struct TALER_EXCHANGE_AdminAddIncomingHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * HTTP headers for the request.
@@ -73,11 +73,6 @@ struct TALER_EXCHANGE_AdminAddIncomingHandle
    */
   void *cb_cls;
 
-  /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
 };
 
 
@@ -86,20 +81,17 @@ struct TALER_EXCHANGE_AdminAddIncomingHandle
  * HTTP /admin/add/incoming request.
  *
  * @param cls the `struct TALER_EXCHANGE_AdminAddIncomingHandle`
- * @param eh the curl request handle
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_admin_add_incoming_finished (void *cls,
-                                    CURL *eh)
+                                    long response_code,
+                                    const json_t *json)
 {
   struct TALER_EXCHANGE_AdminAddIncomingHandle *aai = cls;
-  long response_code;
-  json_t *json;
 
   aai->job = NULL;
-  json = MAC_download_get_result (&aai->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -138,7 +130,6 @@ handle_admin_add_incoming_finished (void *cls,
   aai->cb (aai->cb_cls,
            response_code,
            json);
-  json_decref (json);
   TALER_EXCHANGE_admin_add_incoming_cancel (aai);
 }
 
@@ -170,7 +161,7 @@ TALER_EXCHANGE_admin_add_incoming (struct TALER_EXCHANGE_Handle *exchange,
                                void *res_cb_cls)
 {
   struct TALER_EXCHANGE_AdminAddIncomingHandle *aai;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   json_t *admin_obj;
   CURL *eh;
 
@@ -212,20 +203,12 @@ TALER_EXCHANGE_admin_add_incoming (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_POSTFIELDSIZE,
                                    strlen (aai->json_enc)));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &aai->db));
   ctx = MAH_handle_to_context (exchange);
-  aai->job = MAC_job_add (ctx,
-                          eh,
-                          GNUNET_YES,
-                          &handle_admin_add_incoming_finished,
-                          aai);
+  aai->job = GNUNET_CURL_job_add (ctx,
+                                  eh,
+                                  GNUNET_YES,
+                                  &handle_admin_add_incoming_finished,
+                                  aai);
   return aai;
 }
 
@@ -241,11 +224,10 @@ TALER_EXCHANGE_admin_add_incoming_cancel (struct TALER_EXCHANGE_AdminAddIncoming
 {
   if (NULL != aai->job)
   {
-    MAC_job_cancel (aai->job);
+    GNUNET_CURL_job_cancel (aai->job);
     aai->job = NULL;
   }
   curl_slist_free_all (aai->headers);
-  GNUNET_free_non_null (aai->db.buf);
   GNUNET_free (aai->url);
   GNUNET_free (aai->json_enc);
   GNUNET_free (aai);
diff --git a/src/exchange-lib/exchange_api_common.c b/src/exchange-lib/exchange_api_common.c
index aacbb4a2a..c46b69a40 100644
--- a/src/exchange-lib/exchange_api_common.c
+++ b/src/exchange-lib/exchange_api_common.c
@@ -22,7 +22,7 @@
 #include "platform.h"
 #include "exchange_api_common.h"
 #include "taler_json_lib.h"
-#include "exchange_api_context.h"
+#include <gnunet/gnunet_curl_lib.h>
 #include "exchange_api_handle.h"
 #include "taler_signatures.h"
 
diff --git a/src/exchange-lib/exchange_api_context.c b/src/exchange-lib/exchange_api_context.c
deleted file mode 100644
index 5049bb0a1..000000000
--- a/src/exchange-lib/exchange_api_context.c
+++ /dev/null
@@ -1,537 +0,0 @@
-/*
-  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 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)
-{
-  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 */
diff --git a/src/exchange-lib/exchange_api_context.h b/src/exchange-lib/exchange_api_context.h
deleted file mode 100644
index ed954c696..000000000
--- a/src/exchange-lib/exchange_api_context.h
+++ /dev/null
@@ -1,169 +0,0 @@
-/*
-  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 */
diff --git a/src/exchange-lib/exchange_api_deposit.c b/src/exchange-lib/exchange_api_deposit.c
index 8ec45a23f..d5dbdcff1 100644
--- a/src/exchange-lib/exchange_api_deposit.c
+++ b/src/exchange-lib/exchange_api_deposit.c
@@ -26,10 +26,10 @@
 #include <microhttpd.h> /* just for HTTP status codes */
 #include <gnunet/gnunet_util_lib.h>
 #include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_json_lib.h"
 #include "taler_exchange_service.h"
 #include "exchange_api_common.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 #include "taler_signatures.h"
 
@@ -58,7 +58,7 @@ struct TALER_EXCHANGE_DepositHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with the result.
@@ -71,11 +71,6 @@ struct TALER_EXCHANGE_DepositHandle
   void *cb_cls;
 
   /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
-  /**
    * Information the exchange should sign in response.
    */
   struct TALER_DepositConfirmationPS depconf;
@@ -103,7 +98,7 @@ struct TALER_EXCHANGE_DepositHandle
  */
 static int
 verify_deposit_signature_ok (const struct TALER_EXCHANGE_DepositHandle *dh,
-                             json_t *json)
+                             const json_t *json)
 {
   struct TALER_ExchangeSignatureP exchange_sig;
   struct TALER_ExchangePublicKeyP exchange_pub;
@@ -153,7 +148,7 @@ verify_deposit_signature_ok (const struct TALER_EXCHANGE_DepositHandle *dh,
  */
 static int
 verify_deposit_signature_forbidden (const struct TALER_EXCHANGE_DepositHandle *dh,
-                                    json_t *json)
+                                    const json_t *json)
 {
   json_t *history;
   struct TALER_Amount total;
@@ -162,9 +157,9 @@ verify_deposit_signature_forbidden (const struct TALER_EXCHANGE_DepositHandle *d
                              "history");
   if (GNUNET_OK !=
       TALER_EXCHANGE_verify_coin_history_ (dh->coin_value.currency,
-                                       &dh->depconf.coin_pub,
-                                       history,
-                                       &total))
+                                           &dh->depconf.coin_pub,
+                                           history,
+                                           &total))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
@@ -196,20 +191,17 @@ verify_deposit_signature_forbidden (const struct TALER_EXCHANGE_DepositHandle *d
  * HTTP /deposit request.
  *
  * @param cls the `struct TALER_EXCHANGE_DepositHandle`
- * @param eh the curl request handle
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_deposit_finished (void *cls,
-                         CURL *eh)
+                         long response_code,
+                         const json_t *json)
 {
   struct TALER_EXCHANGE_DepositHandle *dh = cls;
-  long response_code;
-  json_t *json;
 
   dh->job = NULL;
-  json = MAC_download_get_result (&dh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -262,7 +254,6 @@ handle_deposit_finished (void *cls,
   dh->cb (dh->cb_cls,
           response_code,
           json);
-  json_decref (json);
   TALER_EXCHANGE_deposit_cancel (dh);
 }
 
@@ -407,7 +398,7 @@ TALER_EXCHANGE_deposit (struct TALER_EXCHANGE_Handle *exchange,
   const struct TALER_EXCHANGE_Keys *key_state;
   const struct TALER_EXCHANGE_DenomPublicKey *dki;
   struct TALER_EXCHANGE_DepositHandle *dh;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   json_t *deposit_obj;
   CURL *eh;
   struct GNUNET_HashCode h_wire;
@@ -529,16 +520,8 @@ TALER_EXCHANGE_deposit (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_POSTFIELDSIZE,
                                    strlen (dh->json_enc)));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &dh->db));
   ctx = MAH_handle_to_context (exchange);
-  dh->job = MAC_job_add (ctx,
+  dh->job = GNUNET_CURL_job_add (ctx,
                          eh,
                          GNUNET_YES,
                          &handle_deposit_finished,
@@ -558,10 +541,9 @@ TALER_EXCHANGE_deposit_cancel (struct TALER_EXCHANGE_DepositHandle *deposit)
 {
   if (NULL != deposit->job)
   {
-    MAC_job_cancel (deposit->job);
+    GNUNET_CURL_job_cancel (deposit->job);
     deposit->job = NULL;
   }
-  GNUNET_free_non_null (deposit->db.buf);
   GNUNET_free (deposit->url);
   GNUNET_free (deposit->json_enc);
   GNUNET_free (deposit);
diff --git a/src/exchange-lib/exchange_api_deposit_wtid.c b/src/exchange-lib/exchange_api_deposit_wtid.c
index 1ad1dd019..dc3bf1677 100644
--- a/src/exchange-lib/exchange_api_deposit_wtid.c
+++ b/src/exchange-lib/exchange_api_deposit_wtid.c
@@ -25,10 +25,10 @@
 #include <microhttpd.h> /* just for HTTP status codes */
 #include <gnunet/gnunet_util_lib.h>
 #include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_json_lib.h"
 #include "taler_exchange_service.h"
 #include "exchange_api_common.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 #include "taler_signatures.h"
 
@@ -57,7 +57,7 @@ struct TALER_EXCHANGE_DepositWtidHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with the result.
@@ -70,11 +70,6 @@ struct TALER_EXCHANGE_DepositWtidHandle
   void *cb_cls;
 
   /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
-  /**
    * Information the exchange should sign in response.
    * (with pre-filled fields from the request).
    */
@@ -93,7 +88,7 @@ struct TALER_EXCHANGE_DepositWtidHandle
  */
 static int
 verify_deposit_wtid_signature_ok (const struct TALER_EXCHANGE_DepositWtidHandle *dwh,
-                                  json_t *json)
+                                  const json_t *json)
 {
   struct TALER_ExchangeSignatureP exchange_sig;
   struct TALER_ExchangePublicKeyP exchange_pub;
@@ -138,24 +133,21 @@ verify_deposit_wtid_signature_ok (const struct TALER_EXCHANGE_DepositWtidHandle
  * HTTP /deposit/wtid request.
  *
  * @param cls the `struct TALER_EXCHANGE_DepositWtidHandle`
- * @param eh the curl request handle
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_deposit_wtid_finished (void *cls,
-                              CURL *eh)
+                              long response_code,
+                              const json_t *json)
 {
   struct TALER_EXCHANGE_DepositWtidHandle *dwh = cls;
-  long response_code;
-  json_t *json;
   const struct TALER_WireTransferIdentifierRawP *wtid = NULL;
   struct GNUNET_TIME_Absolute execution_time = GNUNET_TIME_UNIT_FOREVER_ABS;
   const struct TALER_Amount *coin_contribution = NULL;
   struct TALER_Amount coin_contribution_s;
 
   dwh->job = NULL;
-  json = MAC_download_get_result (&dwh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -243,7 +235,6 @@ handle_deposit_wtid_finished (void *cls,
            wtid,
            execution_time,
            coin_contribution);
-  json_decref (json);
   TALER_EXCHANGE_deposit_wtid_cancel (dwh);
 }
 
@@ -263,18 +254,18 @@ handle_deposit_wtid_finished (void *cls,
  */
 struct TALER_EXCHANGE_DepositWtidHandle *
 TALER_EXCHANGE_deposit_wtid (struct TALER_EXCHANGE_Handle *exchange,
-                         const struct TALER_MerchantPrivateKeyP *merchant_priv,
-                         const struct GNUNET_HashCode *h_wire,
-                         const struct GNUNET_HashCode *h_contract,
-                         const struct TALER_CoinSpendPublicKeyP *coin_pub,
-                         uint64_t transaction_id,
-                         TALER_EXCHANGE_DepositWtidCallback cb,
-                         void *cb_cls)
+                             const struct TALER_MerchantPrivateKeyP *merchant_priv,
+                             const struct GNUNET_HashCode *h_wire,
+                             const struct GNUNET_HashCode *h_contract,
+                             const struct TALER_CoinSpendPublicKeyP *coin_pub,
+                             uint64_t transaction_id,
+                             TALER_EXCHANGE_DepositWtidCallback cb,
+                             void *cb_cls)
 {
   struct TALER_DepositTrackPS dtp;
   struct TALER_MerchantSignatureP merchant_sig;
   struct TALER_EXCHANGE_DepositWtidHandle *dwh;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   json_t *deposit_wtid_obj;
   CURL *eh;
 
@@ -341,16 +332,8 @@ TALER_EXCHANGE_deposit_wtid (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_POSTFIELDSIZE,
                                    strlen (dwh->json_enc)));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &dwh->db));
   ctx = MAH_handle_to_context (exchange);
-  dwh->job = MAC_job_add (ctx,
+  dwh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
                           &handle_deposit_wtid_finished,
@@ -370,10 +353,9 @@ TALER_EXCHANGE_deposit_wtid_cancel (struct TALER_EXCHANGE_DepositWtidHandle *dwh
 {
   if (NULL != dwh->job)
   {
-    MAC_job_cancel (dwh->job);
+    GNUNET_CURL_job_cancel (dwh->job);
     dwh->job = NULL;
   }
-  GNUNET_free_non_null (dwh->db.buf);
   GNUNET_free (dwh->url);
   GNUNET_free (dwh->json_enc);
   GNUNET_free (dwh);
diff --git a/src/exchange-lib/exchange_api_handle.c b/src/exchange-lib/exchange_api_handle.c
index 65597126c..bd4746565 100644
--- a/src/exchange-lib/exchange_api_handle.c
+++ b/src/exchange-lib/exchange_api_handle.c
@@ -23,10 +23,10 @@
 #include "platform.h"
 #include <curl/curl.h>
 #include <microhttpd.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_json_lib.h"
 #include "taler_exchange_service.h"
 #include "taler_signatures.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 
 
@@ -78,7 +78,7 @@ struct TALER_EXCHANGE_Handle
   /**
    * The context of this handle
    */
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
 
   /**
    * The URL of the exchange (i.e. "http://exchange.taler.net/")
@@ -134,14 +134,9 @@ struct KeysRequest
   char *url;
 
   /**
-   * Entry for this request with the `struct TALER_EXCHANGE_Context`.
+   * Entry for this request with the `struct GNUNET_CURL_Context`.
    */
-  struct MAC_Job *job;
-
-  /**
-   * Data structure for the download.
-   */
-  struct MAC_DownloadBuffer db;
+  struct GNUNET_CURL_Job *job;
 
 };
 
@@ -156,7 +151,6 @@ struct KeysRequest
 static void
 free_keys_request (struct KeysRequest *kr)
 {
-  GNUNET_free_non_null (kr->db.buf);
   GNUNET_free (kr->url);
   GNUNET_free (kr);
 }
@@ -468,7 +462,7 @@ parse_json_auditor (struct TALER_EXCHANGE_AuditorInformation *auditor,
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error (malformed JSON)
  */
 static int
-decode_keys_json (json_t *resp_obj,
+decode_keys_json (const json_t *resp_obj,
                   struct TALER_EXCHANGE_Keys *key_data)
 {
   struct GNUNET_TIME_Absolute list_issue_date;
@@ -601,21 +595,18 @@ decode_keys_json (json_t *resp_obj,
  * is complete.
  *
  * @param cls the `struct KeysRequest`
- * @param eh easy handle of the original request
+ * @param response_code HTTP response code, 0 on error
+ * @param resp_obj parsed JSON result, NULL on error
  */
 static void
 keys_completed_cb (void *cls,
-                   CURL *eh)
+                   long response_code,
+                   const json_t *resp_obj)
 {
   struct KeysRequest *kr = cls;
   struct TALER_EXCHANGE_Handle *exchange = kr->exchange;
-  json_t *resp_obj;
-  long response_code;
   TALER_EXCHANGE_CertificationCallback cb;
 
-  resp_obj = MAC_download_get_result (&kr->db,
-                                      eh,
-                                      &response_code);
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Received keys from URL `%s' with status %ld.\n",
               kr->url,
@@ -636,8 +627,6 @@ keys_completed_cb (void *cls,
                 response_code);
     break;
   }
-  if (NULL != resp_obj)
-    json_decref (resp_obj);
 
   if (MHD_HTTP_OK != response_code)
   {
@@ -675,7 +664,7 @@ keys_completed_cb (void *cls,
  * @param h the exchange handle to query
  * @return ctx context to execute jobs in
  */
-struct TALER_EXCHANGE_Context *
+struct GNUNET_CURL_Context *
 MAH_handle_to_context (struct TALER_EXCHANGE_Handle *h)
 {
   return h->ctx;
@@ -738,11 +727,11 @@ MAH_path_to_url (struct TALER_EXCHANGE_Handle *h,
  * @return the exchange handle; NULL upon error
  */
 struct TALER_EXCHANGE_Handle *
-TALER_EXCHANGE_connect (struct TALER_EXCHANGE_Context *ctx,
-                    const char *url,
-                    TALER_EXCHANGE_CertificationCallback cert_cb,
-                    void *cert_cb_cls,
-                    ...)
+TALER_EXCHANGE_connect (struct GNUNET_CURL_Context *ctx,
+                        const char *url,
+                        TALER_EXCHANGE_CertificationCallback cert_cb,
+                        void *cert_cb_cls,
+                        ...)
 {
   struct TALER_EXCHANGE_Handle *exchange;
   struct KeysRequest *kr;
@@ -772,19 +761,11 @@ TALER_EXCHANGE_connect (struct TALER_EXCHANGE_Context *ctx,
                  curl_easy_setopt (c,
                                    CURLOPT_URL,
                                    kr->url));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (c,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (c,
-                                   CURLOPT_WRITEDATA,
-                                   &kr->db));
-  kr->job = MAC_job_add (exchange->ctx,
-                         c,
-                         GNUNET_NO,
-                         &keys_completed_cb,
-                         kr);
+  kr->job = GNUNET_CURL_job_add (exchange->ctx,
+                                 c,
+                                 GNUNET_NO,
+                                 &keys_completed_cb,
+                                 kr);
   exchange->kr = kr;
   return exchange;
 }
@@ -802,7 +783,7 @@ TALER_EXCHANGE_disconnect (struct TALER_EXCHANGE_Handle *exchange)
 
   if (NULL != exchange->kr)
   {
-    MAC_job_cancel (exchange->kr->job);
+    GNUNET_CURL_job_cancel (exchange->kr->job);
     free_keys_request (exchange->kr);
     exchange->kr = NULL;
   }
@@ -832,7 +813,7 @@ TALER_EXCHANGE_disconnect (struct TALER_EXCHANGE_Handle *exchange)
  */
 int
 TALER_EXCHANGE_test_signing_key (const struct TALER_EXCHANGE_Keys *keys,
-                             const struct TALER_ExchangePublicKeyP *pub)
+                                 const struct TALER_ExchangePublicKeyP *pub)
 {
   struct GNUNET_TIME_Absolute now;
   unsigned int i;
diff --git a/src/exchange-lib/exchange_api_handle.h b/src/exchange-lib/exchange_api_handle.h
index 48423a7b8..2cf2166d0 100644
--- a/src/exchange-lib/exchange_api_handle.h
+++ b/src/exchange-lib/exchange_api_handle.h
@@ -30,7 +30,7 @@
  * @param h the exchange handle to query
  * @return ctx context to execute jobs in
  */
-struct TALER_EXCHANGE_Context *
+struct GNUNET_CURL_Context *
 MAH_handle_to_context (struct TALER_EXCHANGE_Handle *h);
 
 
diff --git a/src/exchange-lib/exchange_api_refresh.c b/src/exchange-lib/exchange_api_refresh.c
index 5cdf059b7..8435a469c 100644
--- a/src/exchange-lib/exchange_api_refresh.c
+++ b/src/exchange-lib/exchange_api_refresh.c
@@ -25,10 +25,10 @@
 #include <microhttpd.h> /* just for HTTP status codes */
 #include <gnunet/gnunet_util_lib.h>
 #include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_json_lib.h"
 #include "taler_exchange_service.h"
 #include "exchange_api_common.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 #include "taler_signatures.h"
 
@@ -1044,7 +1044,7 @@ struct TALER_EXCHANGE_RefreshMeltHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with refresh melt failure results.
@@ -1057,11 +1057,6 @@ struct TALER_EXCHANGE_RefreshMeltHandle
   void *melt_cb_cls;
 
   /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
-  /**
    * Actual information about the melt operation.
    */
   struct MeltData *md;
@@ -1079,7 +1074,7 @@ struct TALER_EXCHANGE_RefreshMeltHandle
  */
 static int
 verify_refresh_melt_signature_ok (struct TALER_EXCHANGE_RefreshMeltHandle *rmh,
-                                  json_t *json,
+                                  const json_t *json,
                                   uint16_t *noreveal_index)
 {
   struct TALER_ExchangeSignatureP exchange_sig;
@@ -1148,7 +1143,7 @@ verify_refresh_melt_signature_ok (struct TALER_EXCHANGE_RefreshMeltHandle *rmh,
  */
 static int
 verify_refresh_melt_signature_forbidden (struct TALER_EXCHANGE_RefreshMeltHandle *rmh,
-                                         json_t *json)
+                                         const json_t *json)
 {
   json_t *history;
   struct TALER_Amount original_value;
@@ -1265,21 +1260,18 @@ verify_refresh_melt_signature_forbidden (struct TALER_EXCHANGE_RefreshMeltHandle
  * HTTP /refresh/melt request.
  *
  * @param cls the `struct TALER_EXCHANGE_RefreshMeltHandle`
- * @param eh the curl request handle
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_refresh_melt_finished (void *cls,
-                              CURL *eh)
+                              long response_code,
+                              const json_t *json)
 {
   struct TALER_EXCHANGE_RefreshMeltHandle *rmh = cls;
-  long response_code;
-  json_t *json;
   uint16_t noreveal_index = TALER_CNC_KAPPA; /* invalid value */
 
   rmh->job = NULL;
-  json = MAC_download_get_result (&rmh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -1343,7 +1335,6 @@ handle_refresh_melt_finished (void *cls,
                   response_code,
                   UINT16_MAX,
                   json);
-  json_decref (json);
   TALER_EXCHANGE_refresh_melt_cancel (rmh);
 }
 
@@ -1427,7 +1418,7 @@ TALER_EXCHANGE_refresh_melt (struct TALER_EXCHANGE_Handle *exchange,
   json_t *tmp;
   struct TALER_EXCHANGE_RefreshMeltHandle *rmh;
   CURL *eh;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   struct MeltData *md;
   unsigned int i;
   unsigned int j;
@@ -1610,16 +1601,8 @@ TALER_EXCHANGE_refresh_melt (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_POSTFIELDSIZE,
                                    strlen (rmh->json_enc)));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &rmh->db));
   ctx = MAH_handle_to_context (exchange);
-  rmh->job = MAC_job_add (ctx,
+  rmh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
                           &handle_refresh_melt_finished,
@@ -1639,10 +1622,9 @@ TALER_EXCHANGE_refresh_melt_cancel (struct TALER_EXCHANGE_RefreshMeltHandle *rmh
 {
   if (NULL != rmh->job)
   {
-    MAC_job_cancel (rmh->job);
+    GNUNET_CURL_job_cancel (rmh->job);
     rmh->job = NULL;
   }
-  GNUNET_free_non_null (rmh->db.buf);
   free_melt_data (rmh->md); /* does not free 'md' itself */
   GNUNET_free (rmh->md);
   GNUNET_free (rmh->url);
@@ -1678,7 +1660,7 @@ struct TALER_EXCHANGE_RefreshRevealHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with the result.
@@ -1691,11 +1673,6 @@ struct TALER_EXCHANGE_RefreshRevealHandle
   void *reveal_cb_cls;
 
   /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
-  /**
    * Actual information about the melt operation.
    */
   struct MeltData *md;
@@ -1726,7 +1703,7 @@ struct TALER_EXCHANGE_RefreshRevealHandle
  */
 static int
 refresh_reveal_ok (struct TALER_EXCHANGE_RefreshRevealHandle *rrh,
-                   json_t *json,
+                   const json_t *json,
                    struct TALER_CoinSpendPrivateKeyP *coin_privs,
                    struct TALER_DenominationSignature *sigs)
 {
@@ -1820,20 +1797,17 @@ refresh_reveal_ok (struct TALER_EXCHANGE_RefreshRevealHandle *rrh,
  * HTTP /refresh/reveal request.
  *
  * @param cls the `struct TALER_EXCHANGE_RefreshHandle`
- * @param eh the curl request handle
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_refresh_reveal_finished (void *cls,
-                                CURL *eh)
+                                long response_code,
+                                const json_t *json)
 {
   struct TALER_EXCHANGE_RefreshRevealHandle *rrh = cls;
-  long response_code;
-  json_t *json;
 
   rrh->job = NULL;
-  json = MAC_download_get_result (&rrh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -1896,7 +1870,6 @@ handle_refresh_reveal_finished (void *cls,
                     response_code,
                     0, NULL, NULL,
                     json);
-  json_decref (json);
   TALER_EXCHANGE_refresh_reveal_cancel (rrh);
 }
 
@@ -1936,7 +1909,7 @@ TALER_EXCHANGE_refresh_reveal (struct TALER_EXCHANGE_Handle *exchange,
   json_t *reveal_obj;
   json_t *tmp;
   CURL *eh;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   struct MeltData *md;
   unsigned int i;
   unsigned int j;
@@ -2022,16 +1995,8 @@ TALER_EXCHANGE_refresh_reveal (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_POSTFIELDSIZE,
                                    strlen (rrh->json_enc)));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &rrh->db));
   ctx = MAH_handle_to_context (rrh->exchange);
-  rrh->job = MAC_job_add (ctx,
+  rrh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
                           &handle_refresh_reveal_finished,
@@ -2051,10 +2016,9 @@ TALER_EXCHANGE_refresh_reveal_cancel (struct TALER_EXCHANGE_RefreshRevealHandle
 {
   if (NULL != rrh->job)
   {
-    MAC_job_cancel (rrh->job);
+    GNUNET_CURL_job_cancel (rrh->job);
     rrh->job = NULL;
   }
-  GNUNET_free_non_null (rrh->db.buf);
   GNUNET_free (rrh->url);
   GNUNET_free (rrh->json_enc);
   free_melt_data (rrh->md); /* does not free 'md' itself */
diff --git a/src/exchange-lib/exchange_api_refresh_link.c b/src/exchange-lib/exchange_api_refresh_link.c
index 8bb40d7f4..e809c3f14 100644
--- a/src/exchange-lib/exchange_api_refresh_link.c
+++ b/src/exchange-lib/exchange_api_refresh_link.c
@@ -23,9 +23,9 @@
 #include <curl/curl.h>
 #include <microhttpd.h> /* just for HTTP status codes */
 #include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_exchange_service.h"
 #include "taler_json_lib.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 #include "taler_signatures.h"
 
@@ -49,7 +49,7 @@ struct TALER_EXCHANGE_RefreshLinkHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with the result.
@@ -62,11 +62,6 @@ struct TALER_EXCHANGE_RefreshLinkHandle
   void *link_cb_cls;
 
   /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
-  /**
    * Private key of the coin, required to decode link information.
    */
   struct TALER_CoinSpendPrivateKeyP coin_priv;
@@ -89,7 +84,7 @@ struct TALER_EXCHANGE_RefreshLinkHandle
  */
 static int
 parse_refresh_link_coin (const struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
-                         json_t *json,
+                         const json_t *json,
                          const struct TALER_TransferPublicKeyP *trans_pub,
                          const struct TALER_EncryptedLinkSecretP *secret_enc,
                          struct TALER_CoinSpendPrivateKeyP *coin_priv,
@@ -173,7 +168,7 @@ parse_refresh_link_coin (const struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
  */
 static int
 parse_refresh_link_ok (struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
-                       json_t *json)
+                       const json_t *json)
 {
   unsigned int session;
   unsigned int num_coins;
@@ -329,20 +324,17 @@ parse_refresh_link_ok (struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
  * HTTP /refresh/link request.
  *
  * @param cls the `struct TALER_EXCHANGE_RefreshLinkHandle`
- * @param eh the curl request handle
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_refresh_link_finished (void *cls,
-                              CURL *eh)
+                              long response_code,
+                              const json_t *json)
 {
   struct TALER_EXCHANGE_RefreshLinkHandle *rlh = cls;
-  long response_code;
-  json_t *json;
 
   rlh->job = NULL;
-  json = MAC_download_get_result (&rlh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -382,7 +374,6 @@ handle_refresh_link_finished (void *cls,
                   response_code,
                   0, NULL, NULL, NULL,
                   json);
-  json_decref (json);
   TALER_EXCHANGE_refresh_link_cancel (rlh);
 }
 
@@ -409,7 +400,7 @@ TALER_EXCHANGE_refresh_link (struct TALER_EXCHANGE_Handle *exchange,
 {
   struct TALER_EXCHANGE_RefreshLinkHandle *rlh;
   CURL *eh;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   struct TALER_CoinSpendPublicKeyP coin_pub;
   char *pub_str;
   char *arg_str;
@@ -443,16 +434,8 @@ TALER_EXCHANGE_refresh_link (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_URL,
                                    rlh->url));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &rlh->db));
   ctx = MAH_handle_to_context (exchange);
-  rlh->job = MAC_job_add (ctx,
+  rlh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
                           &handle_refresh_link_finished,
@@ -472,10 +455,9 @@ TALER_EXCHANGE_refresh_link_cancel (struct TALER_EXCHANGE_RefreshLinkHandle *rlh
 {
   if (NULL != rlh->job)
   {
-    MAC_job_cancel (rlh->job);
+    GNUNET_CURL_job_cancel (rlh->job);
     rlh->job = NULL;
   }
-  GNUNET_free_non_null (rlh->db.buf);
   GNUNET_free (rlh->url);
   GNUNET_free (rlh);
 }
diff --git a/src/exchange-lib/exchange_api_reserve.c b/src/exchange-lib/exchange_api_reserve.c
index 8c3663244..d3e55ed93 100644
--- a/src/exchange-lib/exchange_api_reserve.c
+++ b/src/exchange-lib/exchange_api_reserve.c
@@ -25,9 +25,9 @@
 #include <microhttpd.h> /* just for HTTP status codes */
 #include <gnunet/gnunet_util_lib.h>
 #include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_exchange_service.h"
 #include "taler_json_lib.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 #include "taler_signatures.h"
 
@@ -53,7 +53,7 @@ struct TALER_EXCHANGE_ReserveStatusHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with the result.
@@ -70,11 +70,6 @@ struct TALER_EXCHANGE_ReserveStatusHandle
    */
   void *cb_cls;
 
-  /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
 };
 
 
@@ -94,7 +89,7 @@ struct TALER_EXCHANGE_ReserveStatusHandle
  *         #GNUNET_SYSERR if there was a protocol violation in @a history
  */
 static int
-parse_reserve_history (json_t *history,
+parse_reserve_history (const json_t *history,
                        const struct TALER_ReservePublicKeyP *reserve_pub,
                        const char *currency,
                        struct TALER_Amount *balance,
@@ -273,20 +268,17 @@ parse_reserve_history (json_t *history,
  * HTTP /reserve/status request.
  *
  * @param cls the `struct TALER_EXCHANGE_ReserveStatusHandle`
- * @param eh curl handle of the request that finished
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_reserve_status_finished (void *cls,
-                                CURL *eh)
+                                long response_code,
+                                const json_t *json)
 {
   struct TALER_EXCHANGE_ReserveStatusHandle *wsh = cls;
-  long response_code;
-  json_t *json;
 
   wsh->job = NULL;
-  json = MAC_download_get_result (&wsh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -382,7 +374,6 @@ handle_reserve_status_finished (void *cls,
              json,
              NULL,
              0, NULL);
-  json_decref (json);
   TALER_EXCHANGE_reserve_status_cancel (wsh);
 }
 
@@ -405,12 +396,12 @@ handle_reserve_status_finished (void *cls,
  */
 struct TALER_EXCHANGE_ReserveStatusHandle *
 TALER_EXCHANGE_reserve_status (struct TALER_EXCHANGE_Handle *exchange,
-                           const struct TALER_ReservePublicKeyP *reserve_pub,
-                           TALER_EXCHANGE_ReserveStatusResultCallback cb,
-                           void *cb_cls)
+                               const struct TALER_ReservePublicKeyP *reserve_pub,
+                               TALER_EXCHANGE_ReserveStatusResultCallback cb,
+                               void *cb_cls)
 {
   struct TALER_EXCHANGE_ReserveStatusHandle *wsh;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   CURL *eh;
   char *pub_str;
   char *arg_str;
@@ -441,16 +432,8 @@ TALER_EXCHANGE_reserve_status (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_URL,
                                    wsh->url));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &wsh->db));
   ctx = MAH_handle_to_context (exchange);
-  wsh->job = MAC_job_add (ctx,
+  wsh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_NO,
                           &handle_reserve_status_finished,
@@ -470,10 +453,9 @@ TALER_EXCHANGE_reserve_status_cancel (struct TALER_EXCHANGE_ReserveStatusHandle
 {
   if (NULL != wsh->job)
   {
-    MAC_job_cancel (wsh->job);
+    GNUNET_CURL_job_cancel (wsh->job);
     wsh->job = NULL;
   }
-  GNUNET_free_non_null (wsh->db.buf);
   GNUNET_free (wsh->url);
   GNUNET_free (wsh);
 }
@@ -505,7 +487,7 @@ struct TALER_EXCHANGE_ReserveWithdrawHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with the result.
@@ -528,11 +510,6 @@ struct TALER_EXCHANGE_ReserveWithdrawHandle
   void *cb_cls;
 
   /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
-  /**
    * Hash of the public key of the coin we are signing.
    */
   struct GNUNET_HashCode c_hash;
@@ -561,7 +538,7 @@ struct TALER_EXCHANGE_ReserveWithdrawHandle
  */
 static int
 reserve_withdraw_ok (struct TALER_EXCHANGE_ReserveWithdrawHandle *wsh,
-                  json_t *json)
+                     const json_t *json)
 {
   struct GNUNET_CRYPTO_RsaSignature *blind_sig;
   struct GNUNET_CRYPTO_RsaSignature *sig;
@@ -619,7 +596,7 @@ reserve_withdraw_ok (struct TALER_EXCHANGE_ReserveWithdrawHandle *wsh,
  */
 static int
 reserve_withdraw_payment_required (struct TALER_EXCHANGE_ReserveWithdrawHandle *wsh,
-                                   json_t *json)
+                                   const json_t *json)
 {
   struct TALER_Amount balance;
   struct TALER_Amount balance_from_history;
@@ -702,20 +679,17 @@ reserve_withdraw_payment_required (struct TALER_EXCHANGE_ReserveWithdrawHandle *
  * HTTP /reserve/withdraw request.
  *
  * @param cls the `struct TALER_EXCHANGE_ReserveWithdrawHandle`
- * @param eh curl handle of the request that finished
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_reserve_withdraw_finished (void *cls,
-                                  CURL *eh)
+                                  long response_code,
+                                  const json_t *json)
 {
   struct TALER_EXCHANGE_ReserveWithdrawHandle *wsh = cls;
-  long response_code;
-  json_t *json;
 
   wsh->job = NULL;
-  json = MAC_download_get_result (&wsh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -774,7 +748,6 @@ handle_reserve_withdraw_finished (void *cls,
              response_code,
              NULL,
              json);
-  json_decref (json);
   TALER_EXCHANGE_reserve_withdraw_cancel (wsh);
 }
 
@@ -801,18 +774,18 @@ handle_reserve_withdraw_finished (void *cls,
  */
 struct TALER_EXCHANGE_ReserveWithdrawHandle *
 TALER_EXCHANGE_reserve_withdraw (struct TALER_EXCHANGE_Handle *exchange,
-                             const struct TALER_EXCHANGE_DenomPublicKey *pk,
-                             const struct TALER_ReservePrivateKeyP *reserve_priv,
-                             const struct TALER_CoinSpendPrivateKeyP *coin_priv,
-                             const struct TALER_DenominationBlindingKey *blinding_key,
-                             TALER_EXCHANGE_ReserveWithdrawResultCallback res_cb,
-                             void *res_cb_cls)
+                                 const struct TALER_EXCHANGE_DenomPublicKey *pk,
+                                 const struct TALER_ReservePrivateKeyP *reserve_priv,
+                                 const struct TALER_CoinSpendPrivateKeyP *coin_priv,
+                                 const struct TALER_DenominationBlindingKey *blinding_key,
+                                 TALER_EXCHANGE_ReserveWithdrawResultCallback res_cb,
+                                 void *res_cb_cls)
 {
   struct TALER_EXCHANGE_ReserveWithdrawHandle *wsh;
   struct TALER_WithdrawRequestPS req;
   struct TALER_ReserveSignatureP reserve_sig;
   struct TALER_CoinSpendPublicKeyP coin_pub;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   struct TALER_Amount amount_with_fee;
   char *coin_ev;
   size_t coin_ev_size;
@@ -894,16 +867,8 @@ TALER_EXCHANGE_reserve_withdraw (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_POSTFIELDSIZE,
                                    strlen (wsh->json_enc)));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &wsh->db));
   ctx = MAH_handle_to_context (exchange);
-  wsh->job = MAC_job_add (ctx,
+  wsh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
                           &handle_reserve_withdraw_finished,
@@ -923,10 +888,9 @@ TALER_EXCHANGE_reserve_withdraw_cancel (struct TALER_EXCHANGE_ReserveWithdrawHan
 {
   if (NULL != sign->job)
   {
-    MAC_job_cancel (sign->job);
+    GNUNET_CURL_job_cancel (sign->job);
     sign->job = NULL;
   }
-  GNUNET_free_non_null (sign->db.buf);
   GNUNET_free (sign->url);
   GNUNET_free (sign->json_enc);
   GNUNET_free (sign);
diff --git a/src/exchange-lib/exchange_api_wire.c b/src/exchange-lib/exchange_api_wire.c
index 0e93a9d20..453da14d2 100644
--- a/src/exchange-lib/exchange_api_wire.c
+++ b/src/exchange-lib/exchange_api_wire.c
@@ -24,11 +24,11 @@
 #include <jansson.h>
 #include <microhttpd.h> /* just for HTTP status codes */
 #include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_exchange_service.h"
 #include "taler_json_lib.h"
 #include "taler_wire_plugin.h"
 #include "exchange_api_common.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 
 
@@ -51,7 +51,7 @@ struct TALER_EXCHANGE_WireHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with the result.
@@ -64,11 +64,6 @@ struct TALER_EXCHANGE_WireHandle
   void *cb_cls;
 
   /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
-  /**
    * Set to the "methods" JSON array returned by the
    * /wire request.
    */
@@ -96,7 +91,7 @@ struct TALER_EXCHANGE_WireHandle
 static int
 verify_wire_method_signature_ok (const struct TALER_EXCHANGE_WireHandle *wh,
                                  const char *method,
-                                 json_t *json)
+                                 const json_t *json)
 {
   const struct TALER_EXCHANGE_Keys *key_state;
   struct TALER_WIRE_Plugin *plugin;
@@ -133,20 +128,18 @@ verify_wire_method_signature_ok (const struct TALER_EXCHANGE_WireHandle *wh,
  * HTTP /wire request.
  *
  * @param cls the `struct TALER_EXCHANGE_WireHandle`
- * @param eh the curl request handle
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_wire_finished (void *cls,
-                      CURL *eh)
+                      long response_code,
+                      const json_t *json)
 {
   struct TALER_EXCHANGE_WireHandle *wh = cls;
-  long response_code;
-  json_t *json;
+  json_t *keep = NULL;
 
   wh->job = NULL;
-  json = MAC_download_get_result (&wh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -155,14 +148,13 @@ handle_wire_finished (void *cls,
     {
       const char *key;
       json_t *method;
-      json_t *keep;
       int ret;
 
       /* We 'keep' methods that we support and that are well-formed;
          we fail (by setting response_code=0) if any method that we do
          support fails to verify. */
       keep = json_object ();
-      json_object_foreach (json, key, method) {
+      json_object_foreach ((json_t *) json, key, method) {
         ret = verify_wire_method_signature_ok (wh,
                                                key,
                                                method);
@@ -184,8 +176,6 @@ handle_wire_finished (void *cls,
       if (0 != response_code)
       {
         /* all supported methods were valid, use 'keep' for 'json' */
-        json_decref (json);
-        json = keep;
         break;
       }
       else
@@ -193,6 +183,7 @@ handle_wire_finished (void *cls,
         /* some supported methods were invalid, release 'keep', preserve
            full 'json' for application-level error handling. */
         json_decref (keep);
+        keep = NULL;
       }
     }
     break;
@@ -219,9 +210,9 @@ handle_wire_finished (void *cls,
   }
   wh->cb (wh->cb_cls,
           response_code,
-          json);
-  if (NULL != json)
-    json_decref (json);
+          (NULL != keep) ? keep : json);
+  if (NULL != keep)
+    json_decref (keep);
   TALER_EXCHANGE_wire_cancel (wh);
 }
 
@@ -252,7 +243,7 @@ TALER_EXCHANGE_wire (struct TALER_EXCHANGE_Handle *exchange,
                      void *wire_cb_cls)
 {
   struct TALER_EXCHANGE_WireHandle *wh;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   CURL *eh;
 
   if (GNUNET_YES !=
@@ -272,16 +263,8 @@ TALER_EXCHANGE_wire (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_URL,
                                    wh->url));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &wh->db));
   ctx = MAH_handle_to_context (exchange);
-  wh->job = MAC_job_add (ctx,
+  wh->job = GNUNET_CURL_job_add (ctx,
                          eh,
                          GNUNET_YES,
                          &handle_wire_finished,
@@ -301,7 +284,7 @@ TALER_EXCHANGE_wire_cancel (struct TALER_EXCHANGE_WireHandle *wh)
 {
   if (NULL != wh->job)
   {
-    MAC_job_cancel (wh->job);
+    GNUNET_CURL_job_cancel (wh->job);
     wh->job = NULL;
   }
   if (NULL != wh->methods)
@@ -309,7 +292,6 @@ TALER_EXCHANGE_wire_cancel (struct TALER_EXCHANGE_WireHandle *wh)
     json_decref (wh->methods);
     wh->methods = NULL;
   }
-  GNUNET_free_non_null (wh->db.buf);
   GNUNET_free (wh->url);
   GNUNET_free (wh);
 }
diff --git a/src/exchange-lib/exchange_api_wire_deposits.c b/src/exchange-lib/exchange_api_wire_deposits.c
index 49a50f640..bcb29e872 100644
--- a/src/exchange-lib/exchange_api_wire_deposits.c
+++ b/src/exchange-lib/exchange_api_wire_deposits.c
@@ -24,10 +24,10 @@
 #include <jansson.h>
 #include <microhttpd.h> /* just for HTTP status codes */
 #include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
 #include "taler_exchange_service.h"
 #include "exchange_api_common.h"
 #include "taler_json_lib.h"
-#include "exchange_api_context.h"
 #include "exchange_api_handle.h"
 #include "taler_signatures.h"
 
@@ -51,7 +51,7 @@ struct TALER_EXCHANGE_WireDepositsHandle
   /**
    * Handle for the request.
    */
-  struct MAC_Job *job;
+  struct GNUNET_CURL_Job *job;
 
   /**
    * Function to call with the result.
@@ -63,11 +63,6 @@ struct TALER_EXCHANGE_WireDepositsHandle
    */
   void *cb_cls;
 
-  /**
-   * Download buffer
-   */
-  struct MAC_DownloadBuffer db;
-
 };
 
 
@@ -76,20 +71,17 @@ struct TALER_EXCHANGE_WireDepositsHandle
  * HTTP /wire/deposits request.
  *
  * @param cls the `struct TALER_EXCHANGE_WireDepositsHandle`
- * @param eh the curl request handle
+ * @param response_code HTTP response code, 0 on error
+ * @param json parsed JSON result, NULL on error
  */
 static void
 handle_wire_deposits_finished (void *cls,
-                               CURL *eh)
+                               long response_code,
+                               const json_t *json)
 {
   struct TALER_EXCHANGE_WireDepositsHandle *wdh = cls;
-  long response_code;
-  json_t *json;
 
   wdh->job = NULL;
-  json = MAC_download_get_result (&wdh->db,
-                                  eh,
-                                  &response_code);
   switch (response_code)
   {
   case 0:
@@ -199,7 +191,6 @@ handle_wire_deposits_finished (void *cls,
                  &total_amount,
                  num_details,
                  details);
-        json_decref (json);
         TALER_EXCHANGE_wire_deposits_cancel (wdh);
         return;
       }
@@ -235,7 +226,6 @@ handle_wire_deposits_finished (void *cls,
            response_code,
            json,
            NULL, NULL, 0, NULL);
-  json_decref (json);
   TALER_EXCHANGE_wire_deposits_cancel (wdh);
 }
 
@@ -257,7 +247,7 @@ TALER_EXCHANGE_wire_deposits (struct TALER_EXCHANGE_Handle *exchange,
                               void *cb_cls)
 {
   struct TALER_EXCHANGE_WireDepositsHandle *wdh;
-  struct TALER_EXCHANGE_Context *ctx;
+  struct GNUNET_CURL_Context *ctx;
   char *buf;
   char *path;
   CURL *eh;
@@ -289,16 +279,8 @@ TALER_EXCHANGE_wire_deposits (struct TALER_EXCHANGE_Handle *exchange,
                  curl_easy_setopt (eh,
                                    CURLOPT_URL,
                                    wdh->url));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEFUNCTION,
-                                   &MAC_download_cb));
-  GNUNET_assert (CURLE_OK ==
-                 curl_easy_setopt (eh,
-                                   CURLOPT_WRITEDATA,
-                                   &wdh->db));
   ctx = MAH_handle_to_context (exchange);
-  wdh->job = MAC_job_add (ctx,
+  wdh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
                           &handle_wire_deposits_finished,
@@ -318,10 +300,9 @@ TALER_EXCHANGE_wire_deposits_cancel (struct TALER_EXCHANGE_WireDepositsHandle *w
 {
   if (NULL != wdh->job)
   {
-    MAC_job_cancel (wdh->job);
+    GNUNET_CURL_job_cancel (wdh->job);
     wdh->job = NULL;
   }
-  GNUNET_free_non_null (wdh->db.buf);
   GNUNET_free (wdh->url);
   GNUNET_free (wdh);
 }
diff --git a/src/exchange-lib/test_exchange_api.c b/src/exchange-lib/test_exchange_api.c
index 3659e119e..2936f68fb 100644
--- a/src/exchange-lib/test_exchange_api.c
+++ b/src/exchange-lib/test_exchange_api.c
@@ -40,7 +40,7 @@
 /**
  * Main execution context for the main loop.
  */
-static struct TALER_EXCHANGE_Context *ctx;
+static struct GNUNET_CURL_Context *ctx;
 
 /**
  * Handle to access the exchange.
@@ -655,7 +655,7 @@ interpreter_run (void *cls);
 static void
 add_incoming_cb (void *cls,
                  unsigned int http_status,
-                 json_t *full_response)
+                 const json_t *full_response)
 {
   struct InterpreterState *is = cls;
   struct Command *cmd = &is->commands[is->ip];
@@ -756,7 +756,7 @@ compare_reserve_withdraw_history (const struct TALER_EXCHANGE_ReserveHistory *h,
 static void
 reserve_status_cb (void *cls,
                    unsigned int http_status,
-                   json_t *json,
+                   const json_t *json,
                    const struct TALER_Amount *balance,
                    unsigned int history_length,
                    const struct TALER_EXCHANGE_ReserveHistory *history)
@@ -873,7 +873,7 @@ static void
 reserve_withdraw_cb (void *cls,
                      unsigned int http_status,
                      const struct TALER_DenominationSignature *sig,
-                     json_t *full_response)
+                     const json_t *full_response)
 {
   struct InterpreterState *is = cls;
   struct Command *cmd = &is->commands[is->ip];
@@ -928,7 +928,7 @@ reserve_withdraw_cb (void *cls,
 static void
 deposit_cb (void *cls,
             unsigned int http_status,
-            json_t *obj)
+            const json_t *obj)
 {
   struct InterpreterState *is = cls;
   struct Command *cmd = &is->commands[is->ip];
@@ -964,7 +964,7 @@ static void
 melt_cb (void *cls,
          unsigned int http_status,
          uint16_t noreveal_index,
-         json_t *full_response)
+         const json_t *full_response)
 {
   struct InterpreterState *is = cls;
   struct Command *cmd = &is->commands[is->ip];
@@ -1004,7 +1004,7 @@ reveal_cb (void *cls,
            unsigned int num_coins,
            const struct TALER_CoinSpendPrivateKeyP *coin_privs,
            const struct TALER_DenominationSignature *sigs,
-           json_t *full_response)
+           const json_t *full_response)
 {
   struct InterpreterState *is = cls;
   struct Command *cmd = &is->commands[is->ip];
@@ -1071,7 +1071,7 @@ link_cb (void *cls,
          const struct TALER_CoinSpendPrivateKeyP *coin_privs,
          const struct TALER_DenominationSignature *sigs,
          const struct TALER_DenominationPublicKey *pubs,
-         json_t *full_response)
+         const json_t *full_response)
 {
   struct InterpreterState *is = cls;
   struct Command *cmd = &is->commands[is->ip];
@@ -1218,7 +1218,7 @@ find_pk (const struct TALER_EXCHANGE_Keys *keys,
 static void
 wire_cb (void *cls,
          unsigned int http_status,
-         json_t *obj)
+         const json_t *obj)
 {
   struct InterpreterState *is = cls;
   struct Command *cmd = &is->commands[is->ip];
@@ -1281,7 +1281,7 @@ wire_cb (void *cls,
 static void
 wire_deposits_cb (void *cls,
                   unsigned int http_status,
-                  json_t *json,
+                  const json_t *json,
                   const struct GNUNET_HashCode *h_wire,
                   const struct TALER_Amount *total_amount,
                   unsigned int details_length,
@@ -1371,7 +1371,7 @@ wire_deposits_cb (void *cls,
 static void
 deposit_wtid_cb (void *cls,
                  unsigned int http_status,
-                 json_t *json,
+                 const json_t *json,
                  const struct TALER_WireTransferIdentifierRawP *wtid,
                  struct GNUNET_TIME_Absolute execution_time,
                  const struct TALER_Amount *coin_contribution)
@@ -2168,7 +2168,7 @@ do_shutdown (void *cls)
   }
   if (NULL != ctx)
   {
-    TALER_EXCHANGE_fini (ctx);
+    GNUNET_CURL_fini (ctx);
     ctx = NULL;
   }
 }
@@ -2226,18 +2226,18 @@ context_task (void *cls)
   struct GNUNET_TIME_Relative delay;
 
   ctx_task = NULL;
-  TALER_EXCHANGE_perform (ctx);
+  GNUNET_CURL_perform (ctx);
   max_fd = -1;
   timeout = -1;
   FD_ZERO (&read_fd_set);
   FD_ZERO (&write_fd_set);
   FD_ZERO (&except_fd_set);
-  TALER_EXCHANGE_get_select_info (ctx,
-                              &read_fd_set,
-                              &write_fd_set,
-                              &except_fd_set,
-                              &max_fd,
-                              &timeout);
+  GNUNET_CURL_get_select_info (ctx,
+                               &read_fd_set,
+                               &write_fd_set,
+                               &except_fd_set,
+                               &max_fd,
+                               &timeout);
   if (timeout >= 0)
     delay = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS,
                                            timeout);
@@ -2507,7 +2507,7 @@ run (void *cls)
   is = GNUNET_new (struct InterpreterState);
   is->commands = commands;
 
-  ctx = TALER_EXCHANGE_init ();
+  ctx = GNUNET_CURL_init ();
   GNUNET_assert (NULL != ctx);
   ctx_task = GNUNET_SCHEDULER_add_now (&context_task,
                                        ctx);
diff --git a/src/include/taler_exchange_service.h b/src/include/taler_exchange_service.h
index 4a1592cf2..fa240ee9c 100644
--- a/src/include/taler_exchange_service.h
+++ b/src/include/taler_exchange_service.h
@@ -24,6 +24,7 @@
 
 #include <jansson.h>
 #include "taler_util.h"
+#include <gnunet/gnunet_curl_lib.h>
 
 /* ********************* event loop *********************** */
 
@@ -319,7 +320,7 @@ struct TALER_EXCHANGE_Handle;
  * @return the exchange handle; NULL upon error
  */
 struct TALER_EXCHANGE_Handle *
-TALER_EXCHANGE_connect (struct TALER_EXCHANGE_Context *ctx,
+TALER_EXCHANGE_connect (struct GNUNET_CURL_Context *ctx,
                         const char *url,
                         TALER_EXCHANGE_CertificationCallback cert_cb,
                         void *cert_cb_cls,
@@ -409,7 +410,7 @@ struct TALER_EXCHANGE_WireHandle;
 typedef void
 (*TALER_EXCHANGE_WireResultCallback) (void *cls,
                                       unsigned int http_status,
-                                      json_t *obj);
+                                      const json_t *obj);
 
 
 /**
@@ -469,7 +470,7 @@ struct TALER_EXCHANGE_DepositHandle;
 typedef void
 (*TALER_EXCHANGE_DepositResultCallback) (void *cls,
                                          unsigned int http_status,
-                                         json_t *obj);
+                                         const json_t *obj);
 
 
 /**
@@ -612,7 +613,7 @@ struct TALER_EXCHANGE_ReserveHistory
 typedef void
 (*TALER_EXCHANGE_ReserveStatusResultCallback) (void *cls,
                                                unsigned int http_status,
-                                               json_t *json,
+                                               const json_t *json,
                                                const struct TALER_Amount *balance,
                                                unsigned int history_length,
                                                const struct TALER_EXCHANGE_ReserveHistory *history);
@@ -674,7 +675,7 @@ typedef void
 (*TALER_EXCHANGE_ReserveWithdrawResultCallback) (void *cls,
                                                  unsigned int http_status,
                                                  const struct TALER_DenominationSignature *sig,
-                                                 json_t *full_response);
+                                                 const json_t *full_response);
 
 
 /**
@@ -797,9 +798,9 @@ struct TALER_EXCHANGE_RefreshMeltHandle;
  */
 typedef void
 (*TALER_EXCHANGE_RefreshMeltCallback) (void *cls,
-                                   unsigned int http_status,
-                                   uint16_t noreveal_index,
-                                   json_t *full_response);
+                                       unsigned int http_status,
+                                       uint16_t noreveal_index,
+                                       const json_t *full_response);
 
 
 /**
@@ -866,7 +867,7 @@ typedef void
                                          unsigned int num_coins,
                                          const struct TALER_CoinSpendPrivateKeyP *coin_privs,
                                          const struct TALER_DenominationSignature *sigs,
-                                         json_t *full_response);
+                                         const json_t *full_response);
 
 
 /**
@@ -947,7 +948,7 @@ typedef void
                                        const struct TALER_CoinSpendPrivateKeyP *coin_privs,
                                        const struct TALER_DenominationSignature *sigs,
                                        const struct TALER_DenominationPublicKey *pubs,
-                                       json_t *full_response);
+                                       const json_t *full_response);
 
 
 /**
@@ -1003,7 +1004,7 @@ struct TALER_EXCHANGE_AdminAddIncomingHandle;
 typedef void
 (*TALER_EXCHANGE_AdminAddIncomingResultCallback) (void *cls,
                                                   unsigned int http_status,
-                                                  json_t *full_response);
+                                                  const json_t *full_response);
 
 
 /**
@@ -1103,7 +1104,7 @@ struct TALER_WireDepositDetails
 typedef void
 (*TALER_EXCHANGE_WireDepositsCallback)(void *cls,
                                        unsigned int http_status,
-                                       json_t *json,
+                                       const json_t *json,
                                        const struct GNUNET_HashCode *h_wire,
                                        const struct TALER_Amount *total_amount,
                                        unsigned int details_length,
@@ -1161,7 +1162,7 @@ struct TALER_EXCHANGE_DepositWtidHandle;
 typedef void
 (*TALER_EXCHANGE_DepositWtidCallback)(void *cls,
                                       unsigned int http_status,
-                                      json_t *json,
+                                      const json_t *json,
                                       const struct TALER_WireTransferIdentifierRawP *wtid,
                                       struct GNUNET_TIME_Absolute execution_time,
                                       const struct TALER_Amount *coin_contribution);