use getifaddrs(3) instead of libkvm.

Index: src/ifstat_openbsd.c
--- src/ifstat_openbsd.c.orig
+++ src/ifstat_openbsd.c
@@ -27,10 +27,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <net/if.h>
-#include <fcntl.h>
-#include <kvm.h>
-#include <limits.h>
-#include <nlist.h>
+#include <ifaddrs.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -38,21 +35,16 @@
 #include "utils.h"
 
 struct ifstatstate {
-	void	*ifnet_head;
-	kvm_t	*kd;
+	int unused;
 };
 
 /*
- * Do one-time setup stuff for accessing the interface statistics and store
- * the gathered information in an interface statistics state structure.
- * Return the state structure.
+ * Return a dummy state structure.
  */
 ifstatstate_t *
 if_statinit(void)
 {
 	ifstatstate_t	*statep;
-	struct nlist	ifnet[] = { { "_ifnet" }, { NULL }};
-	char		errbuf[_POSIX2_LINE_MAX];
 
 	statep = malloc(sizeof (ifstatstate_t));
 	if (statep == NULL) {
@@ -60,63 +52,44 @@ if_statinit(void)
 		return (NULL);
 	}
 
-	/*
-	 * Just for the duration of kmem_openfiles(), get privileges
-	 * needed to access kmem.
-	 */
-	chpriv(PRIV_GAIN);
-	statep->kd = kvm_openfiles(NULL, NULL, NULL, O_RDONLY, errbuf);
-	chpriv(PRIV_DROP);
-	if (statep->kd == NULL) {
-		warn("cannot access raw kernel memory: %s\n", errbuf);
-		free(statep);
-		return (NULL);
-	}
-
-	if (kvm_nlist(statep->kd, ifnet) == -1) {
-		warn("cannot populate kernel namelist: %s\n",
-		    kvm_geterr(statep->kd));
-		goto fail;
-	}
-
-	if (kvm_read(statep->kd, ifnet->n_value, &statep->ifnet_head,
-	    sizeof (ifnet->n_value)) != sizeof (ifnet->n_value)) {
-		warn("cannot find ifnet list head: %s\n",
-		    kvm_geterr(statep->kd));
-		goto fail;
-	}
-
 	return (statep);
-fail:
-	(void) kvm_close(statep->kd);
-	free(statep);
-	return (NULL);
 }
 
 /*
- * Optionally using state stored in `statep', retrieve stats on interface
- * `ifname', and store the statistics in `ifstatsp'.
+ * Retrieve stats on interface `ifname', and store the statistics in `ifstatsp'.
  */
 int
 if_stats(const char *ifname, ifstatstate_t *statep, ifstats_t *ifstatsp)
 {
-	void		*ifnet_addr = statep->ifnet_head;
-	struct ifnet	ifnet;
+	struct ifaddrs	*ifa0, *ifa;
+	int		 ret = 0;
 
-	for (; ifnet_addr != NULL; ifnet_addr = TAILQ_NEXT(&ifnet, if_list)) {
+	(void)statep;
 
-		if (kvm_read(statep->kd, (unsigned long)ifnet_addr, &ifnet,
-		    sizeof (struct ifnet)) != sizeof (struct ifnet))
-			return (0);
+	if (getifaddrs(&ifa0) != 0) {
+		warn("failed to get interface addresses");
+		return (0);
+	}
 
-		if (strcmp(ifnet.if_xname, ifname) == 0) {
-			ifstatsp->rxbytes = ifnet.if_ibytes;
-			ifstatsp->txbytes = ifnet.if_obytes;
-			return (1);
+	for (ifa = ifa0; ifa != NULL; ifa = ifa->ifa_next) {
+		if (strcmp(ifname, ifa->ifa_name)) {
+			continue;
 		}
+
+		if (ifa->ifa_addr->sa_family == AF_LINK) {
+			struct if_data *ifd = ifa->ifa_data;
+
+			if (ifd != NULL) {
+				ifstatsp->rxbytes = ifd->ifi_ibytes;
+				ifstatsp->txbytes = ifd->ifi_obytes;
+				ret = 1;
+				break;
+			}
+		}
 	}
 
-	return (0);
+	freeifaddrs(ifa0);
+	return (ret);
 }
 
 /*
@@ -125,6 +98,5 @@ if_stats(const char *ifname, ifstatstate_t *statep, if
 void
 if_statfini(ifstatstate_t *statep)
 {
-	(void) kvm_close(statep->kd);
 	free(statep);
 }