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Improve CNAME flattening to avoid unnecessary error logging

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Niall Newman 2023-09-28 12:00:06 +02:00 committed by GitHub
parent b966215e6c
commit ab7993428d
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 14 additions and 5 deletions
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19
pkg/middlewares/requestdecorator/hostresolver.go
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@ -2,6 +2,7 @@ package requestdecorator
import ( import (
"context" "context"
"errors"
"fmt" "fmt"
"net" "net"
"sort" "sort"
@ -65,9 +66,7 @@ func (hr *Resolver) CNAMEFlatten(ctx context.Context, host string) string {
request = resolv.Record request = resolv.Record
} }
if err := hr.cache.Add(host, result, cacheDuration); err != nil { hr.cache.Set(host, result, cacheDuration)
logger.Error(err)
}
return result return result
} }
@ -79,6 +78,10 @@ func cnameResolve(ctx context.Context, host, resolvPath string) (*cnameResolv, e
return nil, fmt.Errorf("invalid resolver configuration file: %s", resolvPath) return nil, fmt.Errorf("invalid resolver configuration file: %s", resolvPath)
} }
if net.ParseIP(host) != nil {
return nil, nil
}
client := &dns.Client{Timeout: 30 * time.Second} client := &dns.Client{Timeout: 30 * time.Second}
m := &dns.Msg{} m := &dns.Msg{}
@ -88,7 +91,11 @@ func cnameResolve(ctx context.Context, host, resolvPath string) (*cnameResolv, e
for _, server := range config.Servers { for _, server := range config.Servers {
tempRecord, err := getRecord(client, m, server, config.Port) tempRecord, err := getRecord(client, m, server, config.Port)
if err != nil { if err != nil {
log.FromContext(ctx).Errorf("Failed to resolve host %s: %v", host, err) if errors.Is(err, errNoCNAMERecord) {
log.FromContext(ctx).Debugf("CNAME lookup for hostname %q: %s", host, err)
continue
}
log.FromContext(ctx).Errorf("CNAME lookup for hostname %q: %s", host, err)
continue continue
} }
result = append(result, tempRecord) result = append(result, tempRecord)
@ -102,6 +109,8 @@ func cnameResolve(ctx context.Context, host, resolvPath string) (*cnameResolv, e
return result[0], nil return result[0], nil
} }
var errNoCNAMERecord = errors.New("no CNAME record for host")
func getRecord(client *dns.Client, msg *dns.Msg, server, port string) (*cnameResolv, error) { func getRecord(client *dns.Client, msg *dns.Msg, server, port string) (*cnameResolv, error) {
resp, _, err := client.Exchange(msg, net.JoinHostPort(server, port)) resp, _, err := client.Exchange(msg, net.JoinHostPort(server, port))
if err != nil { if err != nil {
@ -109,7 +118,7 @@ func getRecord(client *dns.Client, msg *dns.Msg, server, port string) (*cnameRes
} }
if resp == nil || len(resp.Answer) == 0 { if resp == nil || len(resp.Answer) == 0 {
return nil, fmt.Errorf("empty answer for server %s", server) return nil, fmt.Errorf("%w: %s", errNoCNAMERecord, server)
} }
rr, ok := resp.Answer[0].(*dns.CNAME) rr, ok := resp.Answer[0].(*dns.CNAME)