1 /*
2 * Copyright 2012 Daniel Drown <dan-android@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 */
ack_handler(struct nl_msg * msg,void * data)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 */
error_handler(struct sockaddr_nl * nla,struct nlmsgerr * err,void * arg)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 */
alloc_ack_callbacks(int * retval)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