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server.go
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server.go
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package server
import (
"context"
"errors"
"log"
"sync"
"time"
"github.com/abh/geodns/v3/monitor"
"github.com/abh/geodns/v3/querylog"
"github.com/abh/geodns/v3/zones"
"golang.org/x/sync/errgroup"
"github.com/miekg/dns"
"github.com/prometheus/client_golang/prometheus"
)
type serverMetrics struct {
Queries *prometheus.CounterVec
}
// Server ...
type Server struct {
queryLogger querylog.QueryLogger
mux *dns.ServeMux
PublicDebugQueries bool
info *monitor.ServerInfo
metrics *serverMetrics
lock sync.Mutex
dnsServers []*dns.Server
}
// NewServer ...
func NewServer(si *monitor.ServerInfo) *Server {
mux := dns.NewServeMux()
queries := prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "dns_queries_total",
Help: "Number of served queries",
},
[]string{"zone", "qtype", "qname", "rcode"},
)
prometheus.MustRegister(queries)
buildInfo := prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Name: "geodns_build_info",
Help: "GeoDNS build information (in labels)",
},
[]string{"Version", "ID", "IP", "Group"},
)
prometheus.MustRegister(buildInfo)
group := ""
if len(si.Groups) > 0 {
group = si.Groups[0]
}
buildInfo.WithLabelValues(si.Version, si.ID, si.IP, group).Set(1)
startTime := prometheus.NewGauge(
prometheus.GaugeOpts{
Name: "geodns_start_time_seconds",
Help: "Unix time process started",
},
)
prometheus.MustRegister(startTime)
nano := si.Started.UnixNano()
startTime.Set(float64(nano) / 1e9)
metrics := &serverMetrics{
Queries: queries,
}
return &Server{mux: mux, info: si, metrics: metrics}
}
// SetQueryLogger configures the query logger. For now it only supports writing to
// a file (and all zones get logged to the same file).
func (srv *Server) SetQueryLogger(logger querylog.QueryLogger) {
srv.queryLogger = logger
}
// Add adds the Zone to be handled under the specified name
func (srv *Server) Add(name string, zone *zones.Zone) {
srv.mux.HandleFunc(name, srv.setupServerFunc(zone))
}
// Remove removes the zone name from being handled by the server
func (srv *Server) Remove(name string) {
srv.mux.HandleRemove(name)
}
func (srv *Server) setupServerFunc(zone *zones.Zone) func(dns.ResponseWriter, *dns.Msg) {
return func(w dns.ResponseWriter, r *dns.Msg) {
srv.serve(w, r, zone)
}
}
// ServeDNS calls ServeDNS in the dns package
func (srv *Server) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
srv.mux.ServeDNS(w, r)
}
func (srv *Server) addDNSServer(dnsServer *dns.Server) {
srv.lock.Lock()
defer srv.lock.Unlock()
srv.dnsServers = append(srv.dnsServers, dnsServer)
}
// ListenAndServe starts the DNS server on the specified IP
// (both tcp and udp). It returns an error if
// something goes wrong.
func (srv *Server) ListenAndServe(ctx context.Context, ip string) error {
prots := []string{"udp", "tcp"}
g, _ := errgroup.WithContext(ctx)
for _, prot := range prots {
p := prot
g.Go(func() error {
server := &dns.Server{
Addr: ip,
Net: p,
Handler: srv,
}
srv.addDNSServer(server)
log.Printf("Opening on %s %s", ip, p)
if err := server.ListenAndServe(); err != nil {
log.Printf("geodns: failed to setup %s %s: %s", ip, p, err)
return err
}
return nil
})
}
// the servers will be shutdown when Shutdown() is called
return g.Wait()
}
// Shutdown gracefully shuts down the server
func (srv *Server) Shutdown() error {
var errs []error
for _, dnsServer := range srv.dnsServers {
timeoutCtx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
defer cancel()
err := dnsServer.ShutdownContext(timeoutCtx)
if err != nil {
errs = append(errs, err)
}
}
if srv.queryLogger != nil {
err := srv.queryLogger.Close()
if err != nil {
errs = append(errs, err)
}
}
err := errors.Join(errs...)
return err
}