AdGuardHome/internal/aghnet/interfaces.go

119 lines
2.7 KiB
Go
Raw Normal View History

package aghnet
import (
"fmt"
"net"
"time"
"github.com/AdguardTeam/golibs/log"
)
// IPVersion is a documentational alias for int. Use it when the integer means
// IP version.
type IPVersion = int
// IP version constants.
const (
IPVersion4 IPVersion = 4
IPVersion6 IPVersion = 6
)
// NetIface is the interface for network interface methods.
type NetIface interface {
Addrs() ([]net.Addr, error)
}
// IfaceIPAddrs returns the interface's IP addresses.
func IfaceIPAddrs(iface NetIface, ipv IPVersion) (ips []net.IP, err error) {
addrs, err := iface.Addrs()
if err != nil {
return nil, err
}
for _, a := range addrs {
var ip net.IP
switch a := a.(type) {
case *net.IPAddr:
ip = a.IP
case *net.IPNet:
ip = a.IP
default:
continue
}
// Assume that net.(*Interface).Addrs can only return valid IPv4
// and IPv6 addresses. Thus, if it isn't an IPv4 address, it
// must be an IPv6 one.
switch ipv {
case IPVersion4:
if ip4 := ip.To4(); ip4 != nil {
ips = append(ips, ip4)
}
case IPVersion6:
if ip6 := ip.To4(); ip6 == nil {
ips = append(ips, ip)
}
default:
return nil, fmt.Errorf("invalid ip version %d", ipv)
}
}
return ips, nil
}
// IfaceDNSIPAddrs returns IP addresses of the interface suitable to send to
// clients as DNS addresses. If err is nil, addrs contains either no addresses
// or at least two.
//
// It makes up to maxAttempts attempts to get the addresses if there are none,
// each time using the provided backoff. Sometimes an interface needs a few
// seconds to really ititialize.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/2304.
func IfaceDNSIPAddrs(
iface NetIface,
ipv IPVersion,
maxAttempts int,
backoff time.Duration,
) (addrs []net.IP, err error) {
var n int
for n = 1; n <= maxAttempts; n++ {
addrs, err = IfaceIPAddrs(iface, ipv)
if err != nil {
return nil, fmt.Errorf("getting ip addrs: %w", err)
}
if len(addrs) > 0 {
break
}
log.Debug("dhcpv%d: attempt %d: no ip addresses", ipv, n)
time.Sleep(backoff)
}
switch len(addrs) {
case 0:
// Don't return errors in case the users want to try and enable
// the DHCP server later.
t := time.Duration(n) * backoff
log.Error("dhcpv%d: no ip for iface after %d attempts and %s", ipv, n, t)
return nil, nil
case 1:
// Some Android devices use 8.8.8.8 if there is not a secondary
// DNS server. Fix that by setting the secondary DNS address to
// the same address.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/1708.
log.Debug("dhcpv%d: setting secondary dns ip to itself", ipv)
addrs = append(addrs, addrs[0])
default:
// Go on.
}
log.Debug("dhcpv%d: got addresses %s after %d attempts", ipv, addrs, n)
return addrs, nil
}