many small improvements

internal/common/util.go

@@ -0,0 +1,73 @@
+package common
+
+import (
+	"fmt"
+	"net"
+	"strings"
+)
+
+// BroadcastAddr returns the last address in the given network, or the broadcast address.
+func BroadcastAddr(n *net.IPNet) net.IP {
+	// The golang net package doesn't make it easy to calculate the broadcast address. :(
+	var broadcast net.IP
+	if len(n.IP) == 4 {
+		broadcast = net.ParseIP("0.0.0.0").To4()
+	} else {
+		broadcast = net.ParseIP("::")
+	}
+	for i := 0; i < len(n.IP); i++ {
+		broadcast[i] = n.IP[i] | ^n.Mask[i]
+	}
+	return broadcast
+}
+
+//  http://play.golang.org/p/m8TNTtygK0
+func IncreaseIP(ip net.IP) {
+	for j := len(ip) - 1; j >= 0; j-- {
+		ip[j]++
+		if ip[j] > 0 {
+			break
+		}
+	}
+}
+
+// IsIPv6 check if given ip is IPv6
+func IsIPv6(address string) bool {
+	ip := net.ParseIP(address)
+	if ip == nil {
+		return false
+	}
+	return ip.To4() == nil
+}
+
+func ParseStringList(lst string) []string {
+	tokens := strings.Split(lst, ",")
+	validatedTokens := make([]string, 0, len(tokens))
+	for i := range tokens {
+		tokens[i] = strings.TrimSpace(tokens[i])
+		if tokens[i] != "" {
+			validatedTokens = append(validatedTokens, tokens[i])
+		}
+	}
+
+	return validatedTokens
+}
+
+func ListToString(lst []string) string {
+	return strings.Join(lst, ", ")
+}
+
+// https://yourbasic.org/golang/formatting-byte-size-to-human-readable-format/
+func ByteCountSI(b int64) string {
+	const unit = 1000
+	if b < unit {
+		return fmt.Sprintf("%d B", b)
+	}
+	div, exp := int64(unit), 0
+	for n := b / unit; n >= unit; n /= unit {
+		div *= unit
+		exp++
+	}
+	return fmt.Sprintf("%.1f %cB",
+		float64(b)/float64(div), "kMGTPE"[exp])
+}