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plugin/forward: Allow Proxy to be used outside of forward plugin. (#5951)

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* plugin/forward: Move Proxy into pkg/plugin/proxy, to allow forward.Proxy to be used outside of forward plugin.

Signed-off-by: Patrick Downey <patrick.downey@dioadconsulting.com>
This commit is contained in:
Pat Downey
2023-03-24 12:55:51 +00:00
committed by GitHub
parent 47dceabfc6
commit f823825f8a
19 changed files with 529 additions and 210 deletions
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49
plugin/forward/forward.go
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@@ -16,6 +16,7 @@ import (
"github.com/coredns/coredns/plugin/dnstap"
"github.com/coredns/coredns/plugin/metadata"
clog "github.com/coredns/coredns/plugin/pkg/log"
"github.com/coredns/coredns/plugin/pkg/proxy"
"github.com/coredns/coredns/request"
"github.com/miekg/dns"
@@ -25,12 +26,17 @@ import (
var log = clog.NewWithPlugin("forward")
const (
defaultExpire = 10 * time.Second
hcInterval = 500 * time.Millisecond
)
// Forward represents a plugin instance that can proxy requests to another (DNS) server. It has a list
// of proxies each representing one upstream proxy.
type Forward struct {
concurrent int64 // atomic counters need to be first in struct for proper alignment
proxies []*Proxy
proxies []*proxy.Proxy
p Policy
hcInterval time.Duration
@@ -43,7 +49,7 @@ type Forward struct {
expire time.Duration
maxConcurrent int64
opts options // also here for testing
opts proxy.Options // also here for testing
// ErrLimitExceeded indicates that a query was rejected because the number of concurrent queries has exceeded
// the maximum allowed (maxConcurrent)
@@ -56,14 +62,14 @@ type Forward struct {
// New returns a new Forward.
func New() *Forward {
f := &Forward{maxfails: 2, tlsConfig: new(tls.Config), expire: defaultExpire, p: new(random), from: ".", hcInterval: hcInterval, opts: options{forceTCP: false, preferUDP: false, hcRecursionDesired: true, hcDomain: "."}}
f := &Forward{maxfails: 2, tlsConfig: new(tls.Config), expire: defaultExpire, p: new(random), from: ".", hcInterval: hcInterval, opts: proxy.Options{ForceTCP: false, PreferUDP: false, HCRecursionDesired: true, HCDomain: "."}}
return f
}
// SetProxy appends p to the proxy list and starts healthchecking.
func (f *Forward) SetProxy(p *Proxy) {
func (f *Forward) SetProxy(p *proxy.Proxy) {
f.proxies = append(f.proxies, p)
p.start(f.hcInterval)
p.Start(f.hcInterval)
}
// SetTapPlugin appends one or more dnstap plugins to the tap plugin list.
@@ -128,12 +134,12 @@ func (f *Forward) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
if span != nil {
child = span.Tracer().StartSpan("connect", ot.ChildOf(span.Context()))
otext.PeerAddress.Set(child, proxy.addr)
otext.PeerAddress.Set(child, proxy.Addr())
ctx = ot.ContextWithSpan(ctx, child)
}
metadata.SetValueFunc(ctx, "forward/upstream", func() string {
return proxy.addr
return proxy.Addr()
})
var (
@@ -141,14 +147,15 @@ func (f *Forward) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
err error
)
opts := f.opts
for {
ret, err = proxy.Connect(ctx, state, opts)
if err == ErrCachedClosed { // Remote side closed conn, can only happen with TCP.
continue
}
// Retry with TCP if truncated and prefer_udp configured.
if ret != nil && ret.Truncated && !opts.forceTCP && opts.preferUDP {
opts.forceTCP = true
if ret != nil && ret.Truncated && !opts.ForceTCP && opts.PreferUDP {
opts.ForceTCP = true
continue
}
break
@@ -159,7 +166,7 @@ func (f *Forward) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
}
if len(f.tapPlugins) != 0 {
toDnstap(f, proxy.addr, state, opts, ret, start)
toDnstap(f, proxy.Addr(), state, opts, ret, start)
}
upstreamErr = err
@@ -219,13 +226,13 @@ func (f *Forward) isAllowedDomain(name string) bool {
}
// ForceTCP returns if TCP is forced to be used even when the request comes in over UDP.
func (f *Forward) ForceTCP() bool { return f.opts.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 }
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) }
func (f *Forward) List() []*proxy.Proxy { return f.p.List(f.proxies) }
var (
// ErrNoHealthy means no healthy proxies left.
@@ -236,12 +243,16 @@ var (
ErrCachedClosed = errors.New("cached connection was closed by peer")
)
// options holds various options that can be set.
type options struct {
forceTCP bool
preferUDP bool
hcRecursionDesired bool
hcDomain string
// Options holds various Options that can be set.
type Options struct {
// ForceTCP use TCP protocol for upstream DNS request. Has precedence over PreferUDP flag
ForceTCP bool
// PreferUDP use UDP protocol for upstream DNS request.
PreferUDP bool
// HCRecursionDesired sets recursion desired flag for Proxy healthcheck requests
HCRecursionDesired bool
// HCDomain sets domain for Proxy healthcheck requests
HCDomain string
}
var defaultTimeout = 5 * time.Second