implement if_nameindex and if_freenameindex

src/network/if_freenameindex.c

@@ -0,0 +1,7 @@
+#include <net/if.h>
+#include <stdlib.h>
+
+void if_freenameindex(struct if_nameindex *idx)
+{
+	free(idx);
+}

src/network/if_nameindex.c

@@ -0,0 +1,58 @@
+#define _GNU_SOURCE
+#include <net/if.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <errno.h>
+#include "syscall.h"
+
+#include <stdio.h>
+
+static void *do_nameindex(int s, size_t n)
+{
+	size_t i, len;
+	struct ifconf conf;
+	struct if_nameindex *idx;
+
+	idx = malloc(n * (sizeof(struct if_nameindex)+sizeof(struct ifreq)));
+	if (!idx) return 0;
+
+	conf.ifc_buf = (void *)&idx[n];
+	conf.ifc_len = len = n * sizeof(struct ifreq);
+	if (ioctl(s, SIOCGIFCONF, &conf) < 0) {
+		free(idx);
+		return 0;
+	}
+	if (conf.ifc_len == len) {
+		free(idx);
+		return (void *)-1;
+	}
+
+	n = conf.ifc_len / sizeof(struct ifreq);
+	for (i=0; i<n; i++) {
+		if (ioctl(s, SIOCGIFINDEX, &conf.ifc_req[i]) < 0) {
+			i--;
+			n--;
+			continue;
+		}
+		idx[i].if_index = conf.ifc_req[i].ifr_ifindex;
+		idx[i].if_name = conf.ifc_req[i].ifr_name;
+	}
+	idx[i].if_name = 0;
+	idx[i].if_index = 0;
+
+	return idx;
+}
+
+struct if_nameindex *if_nameindex()
+{
+	size_t n;
+	void *p = 0;
+	int s = socket(AF_UNIX, SOCK_DGRAM, 0);
+	if (s>=0) {
+		for (n=0; (p=do_nameindex(s, n)) == (void *)-1; n++);
+		__syscall(SYS_close, s);
+	}
+	errno = ENOBUFS;
+	return p;
+}