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#include <string.h>
#include <stdio.h>
#include "getifn.h"
#include "nlrequest.h"
struct getifn_info {
char ifname[IFNAMSIZ+1];
int idx;
};
int getifn_callback(struct nlmsghdr *n, void *u) {
struct rtattr *a = NULL;
int l;
struct getifn_info *gi = (struct getifn_info*) u;
struct ifinfomsg *i;
if (n->nlmsg_type != RTM_NEWLINK) {
fprintf(stderr, "NETLINK: Got response for wrong request.\n");
return -1;
}
i = NLMSG_DATA(n);
l = NLMSG_PAYLOAD(n, sizeof(struct ifinfomsg));
a = IFLA_RTA(i);
while(RTA_OK(a, l)) {
switch(a->rta_type) {
case IFLA_IFNAME:
if (strncmp(RTA_DATA(a), gi->ifname, IFNAMSIZ) == 0) {
gi->idx = i->ifi_index;
return 0;
}
}
a = RTA_NEXT(a, l);
}
return 0;
}
int getifn(int s, char *iface) {
struct getifn_info gi;
struct {
struct nlmsghdr n;
struct ifinfomsg i;
char a[1024];
} req;
memset(&req, 0, sizeof(req));
req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
req.n.nlmsg_flags = NLM_F_REQUEST|NLM_F_MATCH;
req.n.nlmsg_type = RTM_GETLINK;
req.i.ifi_family = AF_UNSPEC;
req.i.ifi_change = -1;
memset(&gi, 0, sizeof(gi));
strncpy(gi.ifname, iface, IFNAMSIZ);
gi.idx = -1;
if (addattr_l(&req.n, sizeof(req), IFLA_IFNAME, gi.ifname, IFNAMSIZ+1) < 0) {
fprintf(stderr, "Failed to add attribute to netlink message\n");
return -1;
}
if (netlink_request(s, (struct nlmsghdr*) &req, getifn_callback, &gi) < 0)
return -1;
if (gi.idx < 0) {
fprintf(stderr, "Interface '%s' not existent.\n", iface);
return -1;
}
return gi.idx;
}
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