1 /* 2 * Copyright 2012 Daniel Drown <dan-android (at) drown.org> 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 * 16 * netlink_callbacks.c - generic callbacks for netlink responses 17 */ 18 #include <netinet/in.h> 19 #include <net/if.h> 20 21 #include <linux/rtnetlink.h> 22 #include <netlink/handlers.h> 23 #include <netlink/msg.h> 24 25 /* function: ack_handler 26 * generic netlink callback for ack messages 27 * msg - netlink message 28 * data - pointer to an int, stores the success code 29 */ 30 static int ack_handler(__attribute__((unused)) struct nl_msg *msg, void *data) { 31 int *retval = data; 32 *retval = 0; 33 return NL_OK; 34 } 35 36 /* function: error_handler 37 * generic netlink callback for error messages 38 * nla - error source 39 * err - netlink error message 40 * arg - pointer to an int, stores the error code 41 */ 42 static int error_handler(__attribute__((unused)) struct sockaddr_nl *nla, 43 struct nlmsgerr *err, void *arg) { 44 int *retval = arg; 45 if(err->error < 0) { 46 *retval = err->error; 47 } else { 48 *retval = 0; // NLMSG_ERROR used as reply type on no error 49 } 50 return NL_OK; 51 } 52 53 /* function: alloc_ack_callbacks 54 * allocates a set of netlink callbacks. returns NULL on failure. callbacks will modify retval with <0 meaning failure 55 * retval - shared state between caller and callback functions 56 */ 57 struct nl_cb *alloc_ack_callbacks(int *retval) { 58 struct nl_cb *callbacks; 59 60 callbacks = nl_cb_alloc(NL_CB_DEFAULT); 61 if(!callbacks) { 62 return NULL; 63 } 64 nl_cb_set(callbacks, NL_CB_ACK, NL_CB_CUSTOM, ack_handler, retval); 65 nl_cb_err(callbacks, NL_CB_CUSTOM, error_handler, retval); 66 return callbacks; 67 } 68
