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plugin/forward: add prefer_udp option (#1944)

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* plugin/forward: add prefer_udp option

* updated according to code review

 - fixed linter warning
 - removed metric parameter in Proxy.Connect()
This commit is contained in:
Ruslan Drozhdzh
2018-07-07 10:14:21 +03:00
committed by Miek Gieben
parent 7c41f2ce9f
commit bc50901234
8 changed files with 115 additions and 43 deletions
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25
plugin/forward/forward.go
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@@ -33,7 +33,7 @@ type Forward struct {
maxfails uint32
expire time.Duration
forceTCP bool // also here for testing
opts options // also here for testing
Next plugin.Handler
}
@@ -103,9 +103,18 @@ func (f *Forward) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
ret *dns.Msg
err error
)
opts := f.opts
for {
ret, err = proxy.Connect(ctx, state, f.forceTCP, true)
if err != nil && err == ErrCachedClosed { // Remote side closed conn, can only happen with TCP.
ret, err = proxy.Connect(ctx, state, opts)
if err == nil {
break
}
if err == ErrCachedClosed { // Remote side closed conn, can only happen with TCP.
continue
}
// Retry with TCP if truncated and prefer_udp configured
if err == dns.ErrTruncated && !opts.forceTCP && f.opts.preferUDP {
opts.forceTCP = true
continue
}
break
@@ -183,7 +192,10 @@ func (f *Forward) isAllowedDomain(name string) bool {
func (f *Forward) From() string { return f.from }
// ForceTCP returns if TCP is forced to be used even when the request comes in over UDP.
func (f *Forward) ForceTCP() bool { return f.forceTCP }
func (f *Forward) ForceTCP() bool { return f.opts.forceTCP }
// PreferUDP returns if UDP is preferred to be used even when the request comes in over TCP.
func (f *Forward) PreferUDP() bool { return f.opts.preferUDP }
// List returns a set of proxies to be used for this client depending on the policy in f.
func (f *Forward) List() []*Proxy { return f.p.List(f.proxies) }
@@ -206,4 +218,9 @@ const (
sequentialPolicy
)
type options struct {
forceTCP bool
preferUDP bool
}
const defaultTimeout = 5 * time.Second