mirror of https://github.com/daffainfo/nuclei.git
89 lines
1.5 KiB
Go
89 lines
1.5 KiB
Go
package randomip
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import (
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"crypto/rand"
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"net"
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"github.com/pkg/errors"
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iputil "github.com/projectdiscovery/utils/ip"
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randutil "github.com/projectdiscovery/utils/rand"
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)
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const (
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maxIterations = 255
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)
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func GetRandomIPWithCidr(cidrs ...string) (net.IP, error) {
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if len(cidrs) == 0 {
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return nil, errors.Errorf("must specify at least one cidr")
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}
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randIdx, err := randutil.IntN(len(cidrs))
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if err != nil {
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return nil, err
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}
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cidr := cidrs[randIdx]
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if !iputil.IsCIDR(cidr) {
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return nil, errors.Errorf("%s is not a valid cidr", cidr)
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}
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baseIp, ipnet, err := net.ParseCIDR(cidr)
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if err != nil {
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return nil, err
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}
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switch {
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case 255 == ipnet.Mask[len(ipnet.Mask)-1]:
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return baseIp, nil
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case iputil.IsIPv4(baseIp.String()):
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return getRandomIP(ipnet, 4), nil
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case iputil.IsIPv6(baseIp.String()):
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return getRandomIP(ipnet, 16), nil
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default:
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return nil, errors.New("invalid base ip")
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}
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}
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func getRandomIP(ipnet *net.IPNet, size int) net.IP {
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ip := ipnet.IP
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var iteration int
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for iteration < maxIterations {
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iteration++
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ones, _ := ipnet.Mask.Size()
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quotient := ones / 8
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remainder := ones % 8
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var r []byte
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switch size {
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case 4, 16:
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r = make([]byte, size)
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default:
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return ip
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}
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_, err := rand.Read(r)
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if err != nil {
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break
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}
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for i := 0; i <= quotient; i++ {
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if i == quotient {
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shifted := byte(r[i]) >> remainder
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r[i] = ipnet.IP[i] + (^ipnet.IP[i] & shifted)
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} else {
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r[i] = ipnet.IP[i]
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}
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}
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ip = r
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if !ip.Equal(ipnet.IP) {
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break
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}
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}
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return ip
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}
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