The interface index space may be sparsely populated (e.g. when an

interface in the middle is if_detach()'d).  Return (and handle)
 ENOENT when the ifmib(4) is accessed for a nonexistent interface.

MFC after: 14 days

libexec/rpc.rstatd/rstat_proc.c

@@ -51,6 +51,7 @@ static const char rcsid[] =
 #include <sys/param.h>
 
 #include <err.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <kvm.h>
 #include <limits.h>
@@ -294,6 +295,9 @@ updatestat()
 		mib[4] = i;
 		mib[5] = IFDATA_GENERAL;
 		if (sysctl(mib, 6, &ifmd, &len, 0, 0) < 0) {
+			if (errno == ENOENT)
+				continue;
+
 			syslog(LOG_ERR, "sysctl(net.link.ifdata.%d.general)"
 			       ": %m", i);
 			exit(1);

share/man/man4/ifmib.4

@@ -76,7 +76,7 @@ MIB.  The manifest constants for each level in the
 .Ar name
 are defined in
 .Aq Pa net/if_mib.h .
-A count of interfaces (and thus rows in the table) is given by
+The index of the last row in the table is given by
 .Dq Li net.link.generic.system.ifcount
 (or, using the manifest constants,
 .Dv CTL_NET ,
@@ -87,6 +87,10 @@ A count of interfaces (and thus rows in the table) is given by
 A management application searching for a particular interface should
 start with row 1 and continue through the table row-by-row until the
 desired interface is found, or the interface count is reached.
+Note that the table may be sparse, i.e. a given row may not exist,
+indicated by an errno of
+.Er ENOENT .
+Such an error should be ignored, and the next row should be checked.
 .Pp
 The generic interface information, common to all interfaces,
 can be accessed via the following procedure:

sys/net/if_mib.c

@@ -80,7 +80,8 @@ sysctl_ifdata(SYSCTL_HANDLER_ARGS) /* XXX bad syntax! */
 	if (namelen != 2)
 		return EINVAL;
 
-	if (name[0] <= 0 || name[0] > if_index)
+	if (name[0] <= 0 || name[0] > if_index ||
+	    ifaddr_byindex(name[0]) == NULL)
 		return ENOENT;
 
 	ifp = ifaddr_byindex(name[0])->ifa_ifp;

tools/tools/ifinfo/ifinfo.c

@@ -34,6 +34,7 @@
 #include <sys/time.h>
 
 #include <err.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -99,9 +100,13 @@ main(int argc, char **argv)
 		name[3] = IFMIB_IFDATA;
 		name[4] = i;
 		name[5] = IFDATA_GENERAL;
-		if (sysctl(name, 6, &ifmd, &len, 0, 0) < 0)
+		if (sysctl(name, 6, &ifmd, &len, 0, 0) < 0) {
+			if (errno == ENOENT)
+				continue;
+
 			err(EX_OSERR, "sysctl(net.link.ifdata.%d.general)",
 			    i);
+		}
 
 		if (!isit(argc - optind, argv + optind, ifmd.ifmd_name))
 			continue;

usr.sbin/slstat/slstat.c

@@ -120,8 +120,12 @@ main(argc, argv)
 	for (i = 1; ; i++) {
 		name[4] = i;
 
-		if (sysctl(name, 6, &ifmd, &len, 0, 0) < 0)
+		if (sysctl(name, 6, &ifmd, &len, 0, 0) < 0) {
+			if (errno == ENOENT)
+				continue;
+
 			err(1, "sysctl");
+		}
 		if (strncmp(interface, ifmd.ifmd_name, IFNAMSIZ) == 0
 		    && ifmd.ifmd_data.ifi_type == IFT_SLIP) {
 			indx = i;