add netfilter counter support

internal/common/common.go

@@ -141,6 +141,33 @@ func ByteToString(orig []byte) string {
 	return string(orig[l:n])
 }
 
+// ReadInts reads contents from single line file and returns them as []int32.
+func ReadInts(filename string) ([]int64, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return []int64{}, err
+	}
+	defer f.Close()
+
+	var ret []int64
+
+	r := bufio.NewReader(f)
+
+	// The int files that this is concerned with should only be one liners.
+	line, err := r.ReadString('\n')
+	if err != nil {
+		return []int64{}, err
+	}
+
+	i, err := strconv.ParseInt(strings.Trim(line, "\n"), 10, 32)
+	if err != nil {
+		return []int64{}, err
+	}
+	ret = append(ret, i)
+
+	return ret, nil
+}
+
 // Parse to int32 without error
 func mustParseInt32(val string) int32 {
 	vv, _ := strconv.ParseInt(val, 10, 32)

net/net.go

@@ -65,8 +65,8 @@ type NetInterfaceStat struct {
 }
 
 type NetFilterStat struct {
-	ConnTrackCount	int32	`json:"conntrackcount"`
-	ConnTrackMax	int32	`json:"conntrackmax"`
+	ConnTrackCount	int64	`json:"conntrackcount"`
+	ConnTrackMax	int64	`json:"conntrackmax"`
 }
 
 var constMap = map[string]int{

net/net_linux.go

@@ -164,29 +164,27 @@ func NetProtoCounters(protocols []string) ([]NetProtoCountersStat, error) {
 // NetFilterCounters returns iptables conntrack statistics
 // the currently in use conntrack count and the max.
 // If the file does not exist or is invalid it will return nil.
-func NetFilterCounters() (NetFilterStat, error) {
+func NetFilterCounters() ([]NetFilterStat, error) {
 	countfile := "/proc/sys/net/netfilter/nf_conntrack_count"
-	count, err := common.ReadLines(count)
+	maxfile := "/proc/sys/net/netfilter/nf_conntrack_max"
+
+	count, err := common.ReadInts(countfile)
+
+	if err != nil {
+		return nil, err
+	}
+	stats := make([]NetFilterStat, 0, 1)
+	
+	max, err := common.ReadInts(maxfile)
 	if err != nil {
 		return nil, err
 	}
 
-	maxfile := "/proc/sys/net/netfilter/nf_conntrack_max"
-	max, err := common.ReadLines(maxfile)
-	if err != nil {
-		return nil, err
-	}
-	if len(count) != 1 {
-		// format of file has changed
-		return nil, err
-	}
-	if len(max) != 1 {
-		// format of file has changed
-		return nil, err
-	}
-	stats := NetFilterStat{
-		ConnTrackCount: count,
-		ConnTrackMax:   max,
+	payload := NetFilterStat{
+		ConnTrackCount: count[0],
+		ConnTrackMax:   max[0],
 	}
+
+	stats = append(stats, payload)
 	return stats, nil
 }