cloudflared-mirror/tunneldns/tunnel.go

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package tunneldns
import (
"net"
"strconv"
"sync"
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/plugin/cache"
"github.com/pkg/errors"
"github.com/rs/zerolog"
)
const (
LogFieldAddress = "address"
LogFieldURL = "url"
MaxUpstreamConnsDefault = 5
)
// Listener is an adapter between CoreDNS server and Warp runnable
type Listener struct {
server *dnsserver.Server
wg sync.WaitGroup
log *zerolog.Logger
}
// Create a CoreDNS server plugin from configuration
func createConfig(address string, port uint16, p plugin.Handler) *dnsserver.Config {
c := &dnsserver.Config{
Zone: ".",
Transport: "dns",
ListenHosts: []string{address},
Port: strconv.FormatUint(uint64(port), 10),
}
c.AddPlugin(func(next plugin.Handler) plugin.Handler { return p })
return c
}
// Start blocks for serving requests
func (l *Listener) Start(readySignal chan struct{}) error {
defer close(readySignal)
l.log.Info().Str(LogFieldAddress, l.server.Address()).Msg("Starting DNS over HTTPS proxy server")
// Start UDP listener
if udp, err := l.server.ListenPacket(); err == nil {
l.wg.Add(1)
go func() {
_ = l.server.ServePacket(udp)
l.wg.Done()
}()
} else {
return errors.Wrap(err, "failed to create a UDP listener")
}
// Start TCP listener
tcp, err := l.server.Listen()
if err == nil {
l.wg.Add(1)
go func() {
_ = l.server.Serve(tcp)
l.wg.Done()
}()
}
return errors.Wrap(err, "failed to create a TCP listener")
}
// Stop signals server shutdown and blocks until completed
func (l *Listener) Stop() error {
if err := l.server.Stop(); err != nil {
return err
}
l.wg.Wait()
return nil
}
// CreateListener configures the server and bound sockets
func CreateListener(address string, port uint16, upstreams []string, bootstraps []string, maxUpstreamConnections int, log *zerolog.Logger) (*Listener, error) {
// Build the list of upstreams
upstreamList := make([]Upstream, 0)
for _, url := range upstreams {
log.Info().Str(LogFieldURL, url).Msg("Adding DNS upstream")
upstream, err := NewUpstreamHTTPS(url, bootstraps, maxUpstreamConnections, log)
if err != nil {
return nil, errors.Wrap(err, "failed to create HTTPS upstream")
}
upstreamList = append(upstreamList, upstream)
}
// Create a local cache with HTTPS proxy plugin
chain := cache.New()
chain.Next = ProxyPlugin{
Upstreams: upstreamList,
}
// Format an endpoint
endpoint := "dns://" + net.JoinHostPort(address, strconv.FormatUint(uint64(port), 10))
// Create the actual middleware server
server, err := dnsserver.NewServer(endpoint, []*dnsserver.Config{createConfig(address, port, NewMetricsPlugin(chain))})
if err != nil {
return nil, err
}
return &Listener{server: server, log: log}, nil
}