netbird/client/internal/dns/upstream_ios.go
2024-01-29 17:10:47 +01:00

94 lines
2.3 KiB
Go

//go:build ios
package dns
import (
"context"
"net"
"syscall"
"time"
"github.com/miekg/dns"
log "github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
type upstreamResolverIOS struct {
*upstreamResolverBase
lIP net.IP
lNet *net.IPNet
iIndex int
}
func newUpstreamResolver(parentCTX context.Context, interfaceName string, ip net.IP, net *net.IPNet) (*upstreamResolverIOS, error) {
upstreamResolverBase := newUpstreamResolverBase(parentCTX)
index, err := getInterfaceIndex(interfaceName)
if err != nil {
log.Debugf("unable to get interface index for %s: %s", interfaceName, err)
return nil, err
}
ios := &upstreamResolverIOS{
upstreamResolverBase: upstreamResolverBase,
lIP: ip,
lNet: net,
iIndex: index,
}
ios.upstreamClient = ios
return ios, nil
}
func (u *upstreamResolverIOS) exchange(ctx context.Context, upstream string, r *dns.Msg) (rm *dns.Msg, t time.Duration, err error) {
client := &dns.Client{}
upstreamHost, _, err := net.SplitHostPort(upstream)
if err != nil {
log.Errorf("error while parsing upstream host: %s", err)
}
upstreamIP := net.ParseIP(upstreamHost)
if u.lNet.Contains(upstreamIP) || net.IP.IsPrivate(upstreamIP) {
log.Debugf("using private client to query upstream: %s", upstream)
client = u.getClientPrivate()
}
return client.ExchangeContext(ctx, r, upstream)
}
// getClientPrivate returns a new DNS client bound to the local IP address of the Netbird interface
// This method is needed for iOS
func (u *upstreamResolverIOS) getClientPrivate() *dns.Client {
dialer := &net.Dialer{
LocalAddr: &net.UDPAddr{
IP: u.lIP,
Port: 0, // Let the OS pick a free port
},
Timeout: upstreamTimeout,
Control: func(network, address string, c syscall.RawConn) error {
var operr error
fn := func(s uintptr) {
operr = unix.SetsockoptInt(int(s), unix.IPPROTO_IP, unix.IP_BOUND_IF, u.iIndex)
}
if err := c.Control(fn); err != nil {
return err
}
if operr != nil {
log.Errorf("error while setting socket option: %s", operr)
}
return operr
},
}
client := &dns.Client{
Dialer: dialer,
}
return client
}
func getInterfaceIndex(interfaceName string) (int, error) {
iface, err := net.InterfaceByName(interfaceName)
return iface.Index, err
}