Merge pull request #11618 from MoLow/master

add contains function

ip/ip-tests.ts

@@ -19,3 +19,4 @@ var buff:any = ip.toBuffer(myIP);
 ip.toString(buff);
 ip.subnet('192.168.1.134', '255.255.255.192');
 ip.cidrSubnet('192.168.1.134/26');
+ip.cidrSubnet('192.168.1.134/26').contains('192.168.1.134');

ip/ip.d.ts

@@ -14,6 +14,7 @@ interface SubnetInfo {
     subnetMaskLength: number;
     numHosts: number;
     length: number;
+    contains(ip: string): boolean;
 }
 
 declare module "ip" {
@@ -112,4 +113,4 @@ declare module "ip" {
      * @param cidr CIDR address.
      */
     export function cidrSubnet(cidr: string): SubnetInfo;
-}
+}