添加掩码格式

ip_range/mask_bits.go

@@ -0,0 +1,34 @@
+package iprange
+
+import "strings"
+
+var maskBits = map[string]int{
+	"255": 8,
+	"254": 7,
+	"252": 6,
+	"248": 5,
+	"240": 4,
+	"224": 3,
+	"192": 2,
+	"128": 1,
+	"0":   0,
+}
+
+func MaskToBits(mask string) int {
+	bits := 0
+
+	secs := strings.Split(mask, ".")
+	if len(secs) != 4 {
+		panic("the mask is incorrect")
+	}
+
+	for _, s := range secs {
+		if v, ok := maskBits[s]; ok {
+			bits += v
+		} else {
+			panic("the mask is incorrect")
+		}
+	}
+
+	return bits
+}