1 files changed, 77 insertions, 0 deletions
diff --git a/src/getifn.c b/src/getifn.c
new file mode 100644
index 0000000..74dfc72
--- /dev/null
+++ b/src/getifn.c
@@ -0,0 +1,77 @@
+#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;
+}