AdGuardHome/internal/dhcpd/helpers.go

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package dhcpd
import (
"encoding/binary"
"fmt"
"net"
)
func isTimeout(err error) bool {
operr, ok := err.(*net.OpError)
if !ok {
return false
}
return operr.Timeout()
}
func parseIPv4(text string) (net.IP, error) {
result := net.ParseIP(text)
if result == nil {
return nil, fmt.Errorf("%s is not an IP address", text)
}
if result.To4() == nil {
return nil, fmt.Errorf("%s is not an IPv4 address", text)
}
return result.To4(), nil
}
// Return TRUE if subnet mask is correct (e.g. 255.255.255.0)
func isValidSubnetMask(mask net.IP) bool {
var n uint32
n = binary.BigEndian.Uint32(mask)
for i := 0; i != 32; i++ {
if n == 0 {
break
}
if (n & 0x80000000) == 0 {
return false
}
n <<= 1
}
return true
}