consul/agent/dns/server.go

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// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1
package dns
import (
"fmt"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/consul/internal/dnsutil"
"net"
"github.com/miekg/dns"
"github.com/hashicorp/go-hclog"
"github.com/hashicorp/consul/acl"
"github.com/hashicorp/consul/agent/config"
"github.com/hashicorp/consul/logging"
)
// DNSRouter is a mock for Router that can be used for testing.
//
//go:generate mockery --name DNSRouter --inpackage
type DNSRouter interface {
HandleRequest(req *dns.Msg, reqCtx Context, remoteAddress net.Addr) *dns.Msg
ServeDNS(w dns.ResponseWriter, req *dns.Msg)
ReloadConfig(newCfg *config.RuntimeConfig) error
}
// Server is used to expose service discovery queries using a DNS interface.
// It implements the agent.dnsServer interface.
type Server struct {
*dns.Server // Used for setting up listeners
Router DNSRouter // Used to routes and parse DNS requests
logger hclog.Logger
}
// Config represent all the DNS configuration required to construct a DNS server.
type Config struct {
AgentConfig *config.RuntimeConfig
EntMeta acl.EnterpriseMeta
Logger hclog.Logger
Processor DiscoveryQueryProcessor
TokenFunc func() string
TranslateAddressFunc func(dc string, addr string, taggedAddresses map[string]string, accept dnsutil.TranslateAddressAccept) string
TranslateServiceAddressFunc func(dc string, address string, taggedAddresses map[string]structs.ServiceAddress, accept dnsutil.TranslateAddressAccept) string
}
// NewServer creates a new DNS server.
func NewServer(config Config) (*Server, error) {
router, err := NewRouter(config)
if err != nil {
return nil, fmt.Errorf("error creating DNS router: %w", err)
}
srv := &Server{
Router: router,
logger: config.Logger.Named(logging.DNS),
}
return srv, nil
}
// ListenAndServe starts the DNS server.
func (d *Server) ListenAndServe(network, addr string, notif func()) error {
d.Server = &dns.Server{
Addr: addr,
Net: network,
Handler: d.Router,
NotifyStartedFunc: notif,
}
if network == "udp" {
d.UDPSize = 65535
}
return d.Server.ListenAndServe()
}
// ReloadConfig hot-reloads the server config with new parameters under config.RuntimeConfig.DNS*
func (d *Server) ReloadConfig(newCfg *config.RuntimeConfig) error {
return d.Router.ReloadConfig(newCfg)
}
// Shutdown stops the DNS server.
func (d *Server) Shutdown() {
if d.Server != nil {
d.logger.Info("Stopping server",
"protocol", "DNS",
"address", d.Server.Addr,
"network", d.Server.Net,
)
err := d.Server.Shutdown()
if err != nil {
d.logger.Error("Error stopping DNS server", "error", err)
}
}
}
// GetAddr is a function to return the server address if is not nil.
func (d *Server) GetAddr() string {
if d.Server != nil {
return d.Server.Addr
}
return ""
}