1 /*
2 * Copyright 2012 Daniel Drown
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 * getaddr.c - get a locally configured address
17 */
18 #include <netinet/in.h>
19 #include <strings.h>
20 #include <string.h>
21 #include <net/if.h>
22
23 #include <linux/rtnetlink.h>
24 #include <netlink/handlers.h>
25 #include <netlink/msg.h>
26
27 #include "getaddr.h"
28 #include "netlink_msg.h"
29 #include "logging.h"
30
31 // shared state between getinterface_ip and getaddr_cb
32 struct target {
33 int family;
34 unsigned int ifindex;
35 union anyip ip;
36 int foundip;
37 };
38
39 /* function: getaddr_cb
40 * callback for getinterface_ip
41 * msg - netlink message
42 * data - (struct target) info for which address we're looking for
43 */
getaddr_cb(struct nl_msg * msg,void * data)44 static int getaddr_cb(struct nl_msg *msg, void *data) {
45 struct ifaddrmsg *ifa_p;
46 struct rtattr *rta_p;
47 int rta_len;
48 struct target *targ_p = (struct target *)data;
49
50 ifa_p = (struct ifaddrmsg *)nlmsg_data(nlmsg_hdr(msg));
51 rta_p = (struct rtattr *)IFA_RTA(ifa_p);
52
53 if(ifa_p->ifa_index != targ_p->ifindex)
54 return NL_OK;
55
56 if(ifa_p->ifa_scope != RT_SCOPE_UNIVERSE)
57 return NL_OK;
58
59 rta_len = RTM_PAYLOAD(nlmsg_hdr(msg));
60 for (; RTA_OK(rta_p, rta_len); rta_p = RTA_NEXT(rta_p, rta_len)) {
61 switch(rta_p->rta_type) {
62 case IFA_ADDRESS:
63 if((targ_p->family == AF_INET6) && !(ifa_p->ifa_flags & IFA_F_SECONDARY)) {
64 memcpy(&targ_p->ip.ip6, RTA_DATA(rta_p), rta_p->rta_len - sizeof(struct rtattr));
65 targ_p->foundip = 1;
66 return NL_OK;
67 }
68 break;
69 case IFA_LOCAL:
70 if(targ_p->family == AF_INET) {
71 memcpy(&targ_p->ip.ip4, RTA_DATA(rta_p), rta_p->rta_len - sizeof(struct rtattr));
72 targ_p->foundip = 1;
73 return NL_OK;
74 }
75 break;
76 }
77 }
78
79 return NL_OK;
80 }
81
82 /* function: error_handler
83 * error callback for getinterface_ip
84 * nla - source of the error message
85 * err - netlink message
86 * arg - (struct target) info for which address we're looking for
87 */
error_handler(struct sockaddr_nl * nla,struct nlmsgerr * err,void * arg)88 static int error_handler(__attribute__((unused)) struct sockaddr_nl *nla,
89 __attribute__((unused)) struct nlmsgerr *err,
90 __attribute__((unused)) void *arg) {
91 return NL_OK;
92 }
93
94 /* function: getinterface_ip
95 * finds the first global non-privacy IP of the given family for the given interface, or returns NULL. caller frees pointer
96 * interface - interface to look for
97 * family - family
98 */
getinterface_ip(const char * interface,int family)99 union anyip *getinterface_ip(const char *interface, int family) {
100 struct ifaddrmsg ifa;
101 struct nl_cb *callbacks = NULL;
102 struct target targ;
103 union anyip *retval = NULL;
104
105 targ.family = family;
106 targ.foundip = 0;
107 targ.ifindex = if_nametoindex(interface);
108 if(targ.ifindex == 0) {
109 return NULL; // interface not found
110 }
111
112 memset(&ifa, 0, sizeof(ifa));
113 ifa.ifa_family = targ.family;
114
115 callbacks = nl_cb_alloc(NL_CB_DEFAULT);
116 if(!callbacks) {
117 goto cleanup;
118 }
119 nl_cb_set(callbacks, NL_CB_VALID, NL_CB_CUSTOM, getaddr_cb, &targ);
120 nl_cb_err(callbacks, NL_CB_CUSTOM, error_handler, &targ);
121
122 // sends message and waits for a response
123 send_ifaddrmsg(RTM_GETADDR, NLM_F_REQUEST | NLM_F_ROOT, &ifa, callbacks);
124
125 if(targ.foundip) {
126 retval = malloc(sizeof(union anyip));
127 if(!retval) {
128 logmsg(ANDROID_LOG_FATAL,"getinterface_ip/out of memory");
129 goto cleanup;
130 }
131 memcpy(retval, &targ.ip, sizeof(union anyip));
132 }
133
134 cleanup:
135 if(callbacks)
136 nl_cb_put(callbacks);
137
138 return retval;
139 }
140