+ * Callback to process a request and produce a response
+ *
+ * @param req_str JSON-encoded request
+ * @param data pointer to a MONS_INSTANCE
+ * @return pointer to the response string or null to send no response
+ */
+static TR_MSG *mons_req_cb(TALLOC_CTX *mem_ctx, TR_MSG *req_msg, void *data)
+{
+ TALLOC_CTX *tmp_ctx = talloc_new(NULL);
+ MONS_INSTANCE *mons = talloc_get_type_abort(data, MONS_INSTANCE);
+ MON_REQ *req = NULL;
+ MON_RESP *resp = NULL;
+ TR_MSG *resp_msg = NULL; /* This is the response value */
+
+ /* Validate inputs */
+ if (req_msg == NULL)
+ goto cleanup;
+
+ req = tr_msg_get_mon_req(req_msg);
+ if (req == NULL) {
+ /* this is an internal error */
+ tr_err("mons_req_cb: Received incorrect message type (was %d, expected %d)",
+ tr_msg_get_msg_type(req_msg),
+ MON_REQUEST);
+ /* TODO send an error response */
+ goto cleanup;
+ }
+
+ /* Allocate a response message */
+ resp_msg = talloc(tmp_ctx, TR_MSG);
+ if (resp_msg == NULL) {
+ /* can't return a message, just emit an error */
+ tr_crit("mons_req_cb: Error allocating response message.");
+ goto cleanup;
+ }
+
+ /* Handle the request */
+ resp = mons_handle_request(resp_msg, mons, req);
+ if (resp == NULL) {
+ /* error processing the request */
+ /* TODO send back an error */
+ goto cleanup;
+ }
+
+ /* Set the response message payload */
+ tr_msg_set_mon_resp(resp_msg, resp);
+
+ /* Put the response message in the caller's context so it does not get freed when we exit */
+ talloc_steal(mem_ctx, resp_msg);
+
+cleanup:
+ talloc_free(tmp_ctx);
+ return resp_msg;
+}
+
+/**