AdGuardHome/dhcpd/helpers.go

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package dhcpd
import (
"encoding/binary"
"fmt"
"net"
"github.com/AdguardTeam/golibs/log"
"github.com/joomcode/errorx"
)
func isTimeout(err error) bool {
operr, ok := err.(*net.OpError)
if !ok {
return false
}
return operr.Timeout()
}
// return first IPv4 address of an interface, if there is any
func getIfaceIPv4(iface *net.Interface) *net.IPNet {
ifaceAddrs, err := iface.Addrs()
if err != nil {
panic(err)
}
for _, addr := range ifaceAddrs {
ipnet, ok := addr.(*net.IPNet)
if !ok {
// not an IPNet, should not happen
log.Fatalf("SHOULD NOT HAPPEN: got iface.Addrs() element %s that is not net.IPNet", addr)
}
if ipnet.IP.To4() == nil {
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log.Tracef("Got IP that is not IPv4: %v", ipnet.IP)
continue
}
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log.Tracef("Got IP that is IPv4: %v", ipnet.IP)
return &net.IPNet{
IP: ipnet.IP.To4(),
Mask: ipnet.Mask,
}
}
return nil
}
func wrapErrPrint(err error, message string, args ...interface{}) error {
var errx error
if err == nil {
errx = fmt.Errorf(message, args...)
} else {
errx = errorx.Decorate(err, message, args...)
}
log.Println(errx.Error())
return errx
}
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
}