commit ecf7e412e286d9d2e9726c63acea4621a885119b
parent 30bd77f847b7ea5eba1aaf2b87c2f64371c8c303
Author: Christian Grothoff <christian@grothoff.org>
Date: Sun, 17 Nov 2019 17:36:12 +0100
add missing file
Diffstat:
1 file changed, 786 insertions(+), 0 deletions(-)
diff --git a/src/sync/sync-httpd_backup_post.c b/src/sync/sync-httpd_backup_post.c
@@ -0,0 +1,786 @@
+/*
+ This file is part of TALER
+ Copyright (C) 2019 Taler Systems SA
+
+ TALER is free software; you can redistribute it and/or modify it under the
+ terms of the GNU Affero 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 Affero General Public License for more details.
+
+ You should have received a copy of the GNU Affero General Public License along with
+ TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file sync-httpd_backup_post.c
+ * @brief functions to handle incoming requests for backups
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "sync-httpd.h"
+#include <gnunet/gnunet_util_lib.h>
+#include "sync-httpd_backup.h"
+#include "sync-httpd_responses.h"
+#include <taler/taler_merchant_service.h>
+#include <taler/taler_signatures.h>
+
+
+/**
+ * How long do we hold an HTTP client connection if
+ * we are awaiting payment before giving up?
+ */
+#define CHECK_PAYMENT_TIMEOUT GNUNET_TIME_relative_multiply ( \
+ GNUNET_TIME_UNIT_MINUTES, 30)
+
+
+/**
+ * Context for an upload operation.
+ */
+struct BackupContext
+{
+
+ /**
+ * Context for cleanup logic.
+ */
+ struct TM_HandlerContext hc;
+
+ /**
+ * Signature of the account holder.
+ */
+ struct SYNC_AccountSignatureP account_sig;
+
+ /**
+ * Public key of the account holder.
+ */
+ struct SYNC_AccountPublicKeyP account;
+
+ /**
+ * Hash of the previous upload, or zeros if first upload.
+ */
+ struct GNUNET_HashCode old_backup_hash;
+
+ /**
+ * Hash of the upload we are receiving right now (as promised
+ * by the client, to be verified!).
+ */
+ struct GNUNET_HashCode new_backup_hash;
+
+ /**
+ * Hash context for the upload.
+ */
+ struct GNUNET_HashContext *hash_ctx;
+
+ /**
+ * Kept in DLL for shutdown handling while suspended.
+ */
+ struct BackupContext *next;
+
+ /**
+ * Kept in DLL for shutdown handling while suspended.
+ */
+ struct BackupContext *prev;
+
+ /**
+ * Used while suspended for resumption.
+ */
+ struct MHD_Connection *con;
+
+ /**
+ * Upload, with as many bytes as we have received so far.
+ */
+ char *upload;
+
+ /**
+ * Used while we are awaiting proposal creation.
+ */
+ struct TALER_MERCHANT_ProposalOperation *po;
+
+ /**
+ * Used while we are waiting payment.
+ */
+ struct TALER_MERCHANT_CheckPaymentOperation *cpo;
+
+ /**
+ * HTTP response code to use on resume, if non-NULL.
+ */
+ struct MHD_Response *resp;
+
+ /**
+ * Order under which the client promised payment, or NULL.
+ */
+ const char *order_id;
+
+ /**
+ * Order ID for the client that we found in our database.
+ */
+ char *existing_order_id;
+
+ /**
+ * Expected total upload size.
+ */
+ size_t upload_size;
+
+ /**
+ * Current offset for the upload.
+ */
+ size_t upload_off;
+
+ /**
+ * HTTP response code to use on resume, if resp is set.
+ */
+ unsigned int response_code;
+
+};
+
+
+/**
+ * Kept in DLL for shutdown handling while suspended.
+ */
+static struct BackupContext *bc_head;
+
+/**
+ * Kept in DLL for shutdown handling while suspended.
+ */
+static struct BackupContext *bc_tail;
+
+
+/**
+ * Service is shutting down, resume all MHD connections NOW.
+ */
+void
+SH_resume_all_bc ()
+{
+ struct BackupContext *bc;
+
+ while (NULL != (bc = bc_head))
+ {
+ GNUNET_CONTAINER_DLL_remove (bc_head,
+ bc_tail,
+ bc);
+ MHD_resume_connection (bc->con);
+ if (NULL != bc->po)
+ {
+ TALER_MERCHANT_proposal_cancel (bc->po);
+ bc->po = NULL;
+ }
+ if (NULL != bc->cpo)
+ {
+ TALER_MERCHANT_check_payment_cancel (bc->cpo);
+ bc->cpo = NULL;
+ }
+ }
+}
+
+
+/**
+ * Function called to clean up a backup context.
+ *
+ * @param hc a `struct BackupContext`
+ */
+static void
+cleanup_ctx (struct TM_HandlerContext *hc)
+{
+ struct BackupContext *bc = (struct BackupContext *) hc;
+
+ if (NULL != bc->po)
+ TALER_MERCHANT_proposal_cancel (bc->po);
+ if (NULL != bc->hash_ctx)
+ GNUNET_CRYPTO_hash_context_abort (bc->hash_ctx);
+ if (NULL != bc->resp)
+ MHD_destroy_response (bc->resp);
+ GNUNET_free_non_null (bc->upload);
+ GNUNET_free (bc);
+}
+
+
+/**
+ * Transmit a payment request for @a order_id on @a connection
+ *
+ * @param connection MHD connection
+ * @param order_id our backend's order ID
+ * @return MHD repsonse to use
+ */
+static struct MHD_Response *
+make_payment_request (const char *order_id)
+{
+ struct MHD_Response *resp;
+
+ /* request payment via Taler */
+ resp = MHD_create_response_from_buffer (0,
+ NULL,
+ MHD_RESPMEM_PERSISTENT);
+ {
+ char *hdr;
+
+ /* TODO: support instances? */
+ GNUNET_asprintf (&hdr,
+ "taler://pay/%s/-/-/%s",
+ SH_backend_url,
+ order_id);
+ GNUNET_break (MHD_YES ==
+ MHD_add_response_header (resp,
+ "Taler",
+ hdr));
+ GNUNET_free (hdr);
+ }
+ return resp;
+}
+
+
+/**
+ * Callbacks of this type are used to serve the result of submitting a
+ * /contract request to a merchant.
+ *
+ * @param cls our `struct BackupContext`
+ * @param http_status HTTP response code, 200 indicates success;
+ * 0 if the backend's reply is bogus (fails to follow the protocol)
+ * @param ec taler-specific error code
+ * @param obj raw JSON reply, or error details if the request failed
+ * @param order_id order id of the newly created order
+ */
+static void
+proposal_cb (void *cls,
+ unsigned int http_status,
+ enum TALER_ErrorCode ec,
+ const json_t *obj,
+ const char *order_id)
+{
+ struct BackupContext *bc = cls;
+ enum SYNC_DB_QueryStatus qs;
+
+ bc->po = NULL;
+ GNUNET_CONTAINER_DLL_remove (bc_head,
+ bc_tail,
+ bc);
+ MHD_resume_connection (bc->con);
+ qs = db->store_payment_TR (db->cls,
+ &bc->account,
+ order_id,
+ &SH_annual_fee);
+ if (0 >= qs)
+ {
+ GNUNET_break (0);
+ bc->resp = SH_RESPONSE_make_error (TALER_EC_SYNC_PAYMENT_CREATE_DB_ERROR,
+ "Failed to persist payment request in sync database");
+ bc->response_code = MHD_HTTP_INTERNAL_SERVER_ERROR;
+ return;
+ }
+
+ bc->resp = make_payment_request (order_id);
+ bc->response_code = MHD_HTTP_PAYMENT_REQUIRED;
+}
+
+
+/**
+ * Function called on all pending payments for the right
+ * account.
+ *
+ * @param cls closure, our `struct BackupContext`
+ * @param timestamp for how long have we been waiting
+ * @param order_id order id in the backend
+ * @param amount how much is the order for
+ */
+static void
+ongoing_payment_cb (void *cls,
+ struct GNUNET_TIME_Absolute timestamp,
+ const char *order_id,
+ const struct TALER_Amount *amount)
+{
+ struct BackupContext *bc = cls;
+
+ if (0 != TALER_amount_cmp (amount,
+ &SH_annual_fee))
+ return; /* can't re-use, fees changed */
+ bc->existing_order_id = GNUNET_strdup (order_id);
+}
+
+
+/**
+ * Helper function used to ask our backend to begin
+ * processing a payment for the user's account.
+ *
+ * @param bc context to begin payment for.
+ */
+static int
+begin_payment (struct BackupContext *bc)
+{
+ json_t *order;
+
+ db->lookup_pending_payments_by_account_TR (db->cls,
+ &bc->account,
+ &ongoing_payment_cb,
+ bc);
+ if (NULL != bc->existing_order_id)
+ {
+ // FIXME: this is incorrect, we should FIRST check
+ // if that payment was ALREADY MADE against our
+ // backend, and only if NOT return payment required here!
+ // (this also means that #begin_payment() and
+ // #handle_database_error() have for now
+ // the wrong signature, as it is possible that we
+ // would continue as if there were no problem!
+ struct MHD_Response *resp;
+ int ret;
+
+ resp = make_payment_request (bc->existing_order_id);
+ GNUNET_free (bc->existing_order_id);
+ bc->existing_order_id = NULL;
+ ret = MHD_queue_response (bc->con,
+ MHD_HTTP_PAYMENT_REQUIRED,
+ resp);
+ MHD_destroy_response (resp);
+ return ret;
+ }
+ GNUNET_CONTAINER_DLL_insert (bc_head,
+ bc_tail,
+ bc);
+ MHD_suspend_connection (bc->con);
+ order = json_pack ("{s:o, s:s, s:s}",
+ "amount", TALER_JSON_from_amount (&SH_annual_fee),
+ "summary", "annual fee for sync service",
+ "fulfillment_url", SH_my_base_url);
+ bc->po = TALER_MERCHANT_order_put (SH_ctx,
+ SH_backend_url,
+ order,
+ &proposal_cb,
+ bc);
+ json_decref (order);
+ return MHD_YES;
+}
+
+
+/**
+ * Callback to process a GET /check-payment request
+ *
+ * @param cls our `struct BackupContext`
+ * @param http_status HTTP status code for this request
+ * @param obj raw response body
+ * @param paid #GNUNET_YES if the payment is settled, #GNUNET_NO if not
+ * settled, $GNUNET_SYSERR on error
+ * (note that refunded payments are returned as paid!)
+ * @param refunded #GNUNET_YES if there is at least on refund on this payment,
+ * #GNUNET_NO if refunded, #GNUNET_SYSERR or error
+ * @param refunded_amount amount that was refunded, NULL if there
+ * was no refund
+ * @param taler_pay_uri the URI that instructs the wallets to process
+ * the payment
+ */
+static void
+check_payment_cb (void *cls,
+ unsigned int http_status,
+ const json_t *obj,
+ int paid,
+ int refunded,
+ struct TALER_Amount *refund_amount,
+ const char *taler_pay_uri)
+{
+ struct BackupContext *bc = cls;
+
+ /* refunds are not supported, verify */
+ bc->cpo = NULL;
+ MHD_resume_connection (bc->con);
+ GNUNET_break ( (GNUNET_NO == refunded) &&
+ (NULL == refund_amount) );
+ if (paid)
+ {
+ enum SYNC_DB_QueryStatus qs;
+
+ qs = db->increment_lifetime_TR (db->cls,
+ &bc->account,
+ bc->order_id,
+ GNUNET_TIME_UNIT_YEARS); /* always annual */
+ if (0 <= qs)
+ return; /* continue as planned */
+ GNUNET_break (0);
+ bc->resp = SH_RESPONSE_make_error (TALER_EC_SYNC_PAYMENT_CONFIRM_DB_ERROR,
+ "Failed to persist payment confirmation in sync database");
+ bc->response_code = MHD_HTTP_INTERNAL_SERVER_ERROR;
+ return; /* continue as planned */
+ }
+ bc->resp = SH_RESPONSE_make_error (TALER_EC_SYNC_PAYMENT_TIMEOUT,
+ "Timeout awaiting promised payment");
+ bc->response_code = MHD_HTTP_REQUEST_TIMEOUT;
+}
+
+
+/**
+ * Helper function used to ask our backend to await
+ * a payment for the user's account.
+ *
+ * @param bc context to begin payment for.
+ * @param timeout when to give up trying
+ * @param order_id which order to check for the payment
+ */
+static void
+await_payment (struct BackupContext *bc,
+ struct GNUNET_TIME_Relative timeout,
+ const char *order_id)
+{
+ GNUNET_CONTAINER_DLL_insert (bc_head,
+ bc_tail,
+ bc);
+ MHD_suspend_connection (bc->con);
+ bc->order_id = order_id;
+ bc->cpo = TALER_MERCHANT_check_payment (SH_ctx,
+ SH_backend_url,
+ order_id,
+ NULL /* our payments are NOT session-bound */,
+ timeout,
+ &check_payment_cb,
+ bc);
+}
+
+
+/**
+ * We got some query status from the DB. Handle the error cases.
+ *
+ * @param bc connection to handle status for
+ * @param qs query status to handle
+ * @return #MHD_YES or #MHD_NO
+ */
+static int
+handle_database_error (struct BackupContext *bc,
+ enum SYNC_DB_QueryStatus qs)
+{
+ switch (qs)
+ {
+ case SYNC_DB_OLD_BACKUP_MISSMATCH:
+ return SH_return_backup (bc->con,
+ &bc->account,
+ MHD_HTTP_CONFLICT);
+ case SYNC_DB_PAYMENT_REQUIRED:
+ {
+ const char *order_id;
+
+ order_id = MHD_lookup_connection_value (bc->con,
+ MHD_GET_ARGUMENT_KIND,
+ "paying");
+ if (NULL == order_id)
+ return begin_payment (bc);
+ await_payment (bc,
+ CHECK_PAYMENT_TIMEOUT,
+ order_id);
+ }
+ return MHD_YES;
+ case SYNC_DB_HARD_ERROR:
+ case SYNC_DB_SOFT_ERROR:
+ GNUNET_break (0);
+ return SH_RESPONSE_reply_internal_error (bc->con,
+ TALER_EC_SYNC_DATABASE_FETCH_ERROR,
+ "failed to fetch existing record from database");
+ case SYNC_DB_NO_RESULTS:
+ GNUNET_assert (0);
+ return MHD_NO;
+ /* intentional fall-through! */
+ case SYNC_DB_ONE_RESULT:
+ GNUNET_assert (0);
+ return MHD_NO;
+ }
+ GNUNET_break (0);
+ return MHD_NO;
+}
+
+
+/**
+ * Handle a client POSTing a backup to us.
+ *
+ * @param connection the MHD connection to handle
+ * @param[in,out] connection_cls the connection's closure (can be updated)
+ * @param account public key of the account the request is for
+ * @param upload_data upload data
+ * @param[in,out] upload_data_size number of bytes (left) in @a upload_data
+ * @return MHD result code
+ */
+int
+sync_handler_backup_post (struct MHD_Connection *connection,
+ void **con_cls,
+ const struct SYNC_AccountPublicKeyP *account,
+ const char *upload_data,
+ size_t *upload_data_size)
+{
+ struct BackupContext *bc;
+
+ bc = *con_cls;
+ if (NULL == bc)
+ {
+ /* first call, setup internals */
+ bc = GNUNET_new (struct BackupContext);
+ bc->hc.cc = &cleanup_ctx;
+ bc->con = connection;
+ bc->account = *account;
+ *con_cls = bc;
+
+ /* now setup 'bc' */
+ {
+ const char *lens;
+ unsigned long len;
+
+ lens = MHD_lookup_connection_value (connection,
+ MHD_HEADER_KIND,
+ MHD_HTTP_HEADER_CONTENT_LENGTH);
+ if ( (NULL == lens) ||
+ (1 !=
+ sscanf (lens,
+ "%lu",
+ &len)) )
+ {
+ GNUNET_break_op (0);
+ return SH_RESPONSE_reply_bad_request (connection,
+ TALER_EC_SYNC_BAD_CONTENT_LENGTH,
+ (NULL == lens)
+ ? "Content-length value missing"
+ : "Content-length value malformed");
+ }
+ if (len / 1024 / 1024 >= SH_upload_limit_mb)
+ {
+ GNUNET_break_op (0);
+ return SH_RESPONSE_reply_rc (connection,
+ MHD_HTTP_PAYLOAD_TOO_LARGE,
+ TALER_EC_SYNC_BAD_CONTENT_LENGTH,
+ "Content-length value not acceptable");
+ }
+ bc->upload = GNUNET_malloc_large (len);
+ if (NULL == bc->upload)
+ {
+ GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
+ "malloc");
+ return SH_RESPONSE_reply_rc (connection,
+ MHD_HTTP_PAYLOAD_TOO_LARGE,
+ TALER_EC_SYNC_OUT_OF_MEMORY_ON_CONTENT_LENGTH,
+ "Server out of memory, try again later");
+ }
+ bc->upload_size = (size_t) len;
+ }
+ {
+ const char *im;
+
+ im = MHD_lookup_connection_value (connection,
+ MHD_HEADER_KIND,
+ MHD_HTTP_HEADER_IF_MATCH);
+ if ( (NULL != im) &&
+ (GNUNET_OK !=
+ GNUNET_STRINGS_string_to_data (im,
+ strlen (im),
+ &bc->old_backup_hash,
+ sizeof (&bc->old_backup_hash))) )
+ {
+ GNUNET_break_op (0);
+ return SH_RESPONSE_reply_bad_request (connection,
+ TALER_EC_SYNC_BAD_IF_MATCH,
+ "If-Match does not include not a base32-encoded SHA-512 hash");
+ }
+ }
+ {
+ const char *sig_s;
+
+ sig_s = MHD_lookup_connection_value (connection,
+ MHD_HEADER_KIND,
+ "Sync-Signature");
+ if ( (NULL == sig_s) ||
+ (GNUNET_OK !=
+ GNUNET_STRINGS_string_to_data (sig_s,
+ strlen (sig_s),
+ &bc->account_sig,
+ sizeof (&bc->account_sig))) )
+ {
+ GNUNET_break_op (0);
+ return SH_RESPONSE_reply_bad_request (connection,
+ TALER_EC_SYNC_BAD_SYNC_SIGNATURE,
+ "Sync-Signature does not include a base32-encoded EdDSA signature");
+ }
+ }
+ {
+ const char *etag;
+
+ etag = MHD_lookup_connection_value (connection,
+ MHD_HEADER_KIND,
+ MHD_HTTP_HEADER_ETAG);
+ if ( (NULL == etag) ||
+ (GNUNET_OK !=
+ GNUNET_STRINGS_string_to_data (etag,
+ strlen (etag),
+ &bc->new_backup_hash,
+ sizeof (&bc->new_backup_hash))) )
+ {
+ GNUNET_break_op (0);
+ return SH_RESPONSE_reply_bad_request (connection,
+ TALER_EC_SYNC_BAD_ETAG,
+ "Etag does not include not a base32-encoded SHA-512 hash");
+ }
+ }
+ /* validate signature */
+ {
+ struct SYNC_UploadSignaturePS usp;
+
+ usp.purpose.size = htonl (sizeof (struct SYNC_UploadSignaturePS));
+ usp.purpose.purpose = htonl (TALER_SIGNATURE_SYNC_BACKUP_UPLOAD);
+ usp.old_backup_hash = bc->old_backup_hash;
+ usp.new_backup_hash = bc->new_backup_hash;
+ if (GNUNET_OK !=
+ GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_SYNC_BACKUP_UPLOAD,
+ &usp.purpose,
+ &bc->account_sig.eddsa_sig,
+ &account->eddsa_pub))
+ {
+ GNUNET_break_op (0);
+ return SH_RESPONSE_reply_rc (connection,
+ MHD_HTTP_UNAUTHORIZED,
+ TALER_EC_SYNC_INVALID_SIGNATURE,
+ "Account signature does not match upload");
+ }
+ }
+ /* get ready to hash (done here as we may go async for payments next) */
+ bc->hash_ctx = GNUNET_CRYPTO_hash_context_start ();
+
+ /* Check database to see if the transaction is permissable */
+ {
+ struct GNUNET_HashCode hc;
+ enum SYNC_DB_QueryStatus qs;
+
+ qs = db->lookup_account_TR (db->cls,
+ account,
+ &hc);
+ if (qs < 0)
+ return handle_database_error (bc,
+ qs);
+ if (SYNC_DB_NO_RESULTS == qs)
+ memset (&hc, 0, sizeof (hc));
+ if (0 == GNUNET_memcmp (&hc,
+ &bc->new_backup_hash))
+ {
+ /* Refuse upload: we already have that backup! */
+ struct MHD_Response *resp;
+ int ret;
+
+ resp = MHD_create_response_from_buffer (0,
+ NULL,
+ MHD_RESPMEM_PERSISTENT);
+ ret = MHD_queue_response (connection,
+ MHD_HTTP_NOT_MODIFIED,
+ resp);
+ MHD_destroy_response (resp);
+ return ret;
+ }
+ if (0 != GNUNET_memcmp (&hc,
+ &bc->old_backup_hash))
+ {
+ /* Refuse upload: if-none-match failed! */
+ return SH_return_backup (connection,
+ account,
+ MHD_HTTP_CONFLICT);
+ }
+ }
+ /* check if the client insists on paying */
+ {
+ const char *order_req;
+
+ order_req = MHD_lookup_connection_value (connection,
+ MHD_GET_ARGUMENT_KIND,
+ "pay");
+ if (NULL != order_req)
+ {
+ begin_payment (bc);
+ return MHD_YES;
+ }
+ }
+ /* ready to begin! */
+ return MHD_YES;
+ }
+ /* handle upload */
+ if (0 != upload_data_size)
+ {
+ /* check MHD invariant */
+ GNUNET_assert (bc->upload_off + *upload_data_size <= bc->upload_size);
+ memcpy (&bc->upload[bc->upload_off],
+ upload_data,
+ *upload_data_size);
+ bc->upload_off += *upload_data_size;
+ GNUNET_CRYPTO_hash_context_read (bc->hash_ctx,
+ upload_data,
+ *upload_data_size);
+ *upload_data_size = 0;
+ return MHD_YES;
+ }
+ if (NULL != bc->resp)
+ {
+ /* We generated a response asynchronously, queue that */
+ return MHD_queue_response (connection,
+ bc->response_code,
+ bc->resp);
+ }
+
+ /* finished with upload, check hash */
+ {
+ struct GNUNET_HashCode our_hash;
+
+ GNUNET_CRYPTO_hash_context_finish (bc->hash_ctx,
+ &our_hash);
+ bc->hash_ctx = NULL;
+ if (0 != GNUNET_memcmp (&our_hash,
+ &bc->new_backup_hash))
+ {
+ GNUNET_break_op (0);
+ return SH_RESPONSE_reply_bad_request (connection,
+ TALER_EC_SYNC_INVALID_UPLOAD,
+ "Data uploaded does not match Etag promise");
+ }
+ }
+
+ /* store backup to database */
+ {
+ enum SYNC_DB_QueryStatus qs;
+
+ if (GNUNET_is_zero (&bc->old_backup_hash))
+ qs = db->store_backup_TR (db->cls,
+ account,
+ &bc->account_sig,
+ &bc->new_backup_hash,
+ bc->upload_size,
+ bc->upload);
+ else
+ qs = db->update_backup_TR (db->cls,
+ account,
+ &bc->old_backup_hash,
+ &bc->account_sig,
+ &bc->new_backup_hash,
+ bc->upload_size,
+ bc->upload);
+ if (qs < 0)
+ return handle_database_error (bc,
+ qs);
+ if (0 == qs)
+ {
+ /* database says nothing actually changed, 304 (could
+ theoretically happen if another equivalent upload succeeded
+ since we last checked!) */
+ struct MHD_Response *resp;
+ int ret;
+
+ resp = MHD_create_response_from_buffer (0,
+ NULL,
+ MHD_RESPMEM_PERSISTENT);
+ ret = MHD_queue_response (connection,
+ MHD_HTTP_NOT_MODIFIED,
+ resp);
+ MHD_destroy_response (resp);
+ return ret;
+ }
+ }
+
+ /* generate main (204) standard success reply */
+ {
+ struct MHD_Response *resp;
+ int ret;
+
+ resp = MHD_create_response_from_buffer (0,
+ NULL,
+ MHD_RESPMEM_PERSISTENT);
+ ret = MHD_queue_response (connection,
+ MHD_HTTP_NO_CONTENT,
+ resp);
+ MHD_destroy_response (resp);
+ return ret;
+ }
+}
