diff options
Diffstat (limited to 'plugin/proxy/proxy.go')
| -rw-r--r-- | plugin/proxy/proxy.go | 183 |
1 files changed, 0 insertions, 183 deletions
diff --git a/plugin/proxy/proxy.go b/plugin/proxy/proxy.go deleted file mode 100644 index ad333fbd1..000000000 --- a/plugin/proxy/proxy.go +++ /dev/null @@ -1,183 +0,0 @@ -// Package proxy is plugin that proxies requests. -package proxy - -import ( - "context" - "errors" - "fmt" - "net" - "sync/atomic" - "time" - - "github.com/coredns/coredns/plugin" - "github.com/coredns/coredns/plugin/metrics" - "github.com/coredns/coredns/plugin/pkg/healthcheck" - "github.com/coredns/coredns/request" - - "github.com/miekg/dns" - ot "github.com/opentracing/opentracing-go" -) - -var ( - errUnreachable = errors.New("unreachable backend") - errInvalidProtocol = errors.New("invalid protocol") - errInvalidDomain = errors.New("invalid path for proxy") -) - -// Proxy represents a plugin instance that can proxy requests to another (DNS) server. -type Proxy struct { - Next plugin.Handler - - // Upstreams is a pointer to a slice, so we can update the upstream (used for Google) - // midway. - - Upstreams *[]Upstream - - // Trace is the Trace plugin, if it is installed - // This is used by the grpc exchanger to trace through the grpc calls - Trace plugin.Handler -} - -// Upstream manages a pool of proxy upstream hosts. Select should return a -// suitable upstream host, or nil if no such hosts are available. -type Upstream interface { - // The domain name this upstream host should be routed on. - From() string - // Selects an upstream host to be routed to. - Select() *healthcheck.UpstreamHost - // Checks if subdomain is not an ignored. - IsAllowedDomain(string) bool - // Exchanger returns the exchanger to be used for this upstream. - Exchanger() Exchanger - // Stops the upstream from proxying requests to shutdown goroutines cleanly. - Stop() error -} - -// tryDuration is how long to try upstream hosts; failures result in -// immediate retries until this duration ends or we get a nil host. -var tryDuration = 16 * time.Second - -// ServeDNS satisfies the plugin.Handler interface. -func (p Proxy) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { - var span, child ot.Span - span = ot.SpanFromContext(ctx) - state := request.Request{W: w, Req: r} - - upstream := p.match(state) - if upstream == nil { - return plugin.NextOrFailure(p.Name(), p.Next, ctx, w, r) - } - - for { - start := time.Now() - var reply *dns.Msg - var backendErr error - - // Since Select() should give us "up" hosts, keep retrying - // hosts until timeout (or until we get a nil host). - for time.Since(start) < tryDuration { - host := upstream.Select() - if host == nil { - return dns.RcodeServerFailure, fmt.Errorf("%s: %s", errUnreachable, "no upstream host") - } - - if span != nil { - child = span.Tracer().StartSpan("exchange", ot.ChildOf(span.Context())) - ctx = ot.ContextWithSpan(ctx, child) - } - - atomic.AddInt64(&host.Conns, 1) - - RequestCount.WithLabelValues(metrics.WithServer(ctx), state.Proto(), upstream.Exchanger().Protocol(), familyToString(state.Family()), host.Name).Add(1) - - reply, backendErr = upstream.Exchanger().Exchange(ctx, host.Name, state) - - atomic.AddInt64(&host.Conns, -1) - - if child != nil { - child.Finish() - } - - taperr := toDnstap(ctx, host.Name, upstream.Exchanger(), state, reply, start) - - if backendErr == nil { - - // Check if the reply is correct; if not return FormErr. - if !state.Match(reply) { - formerr := state.ErrorMessage(dns.RcodeFormatError) - w.WriteMsg(formerr) - return 0, taperr - } - - w.WriteMsg(reply) - - RequestDuration.WithLabelValues(metrics.WithServer(ctx), state.Proto(), upstream.Exchanger().Protocol(), familyToString(state.Family()), host.Name).Observe(time.Since(start).Seconds()) - - return 0, taperr - } - - // A "ANY isc.org" query is being dropped by ISC's nameserver, we see this as a i/o timeout, but - // would then mark our upstream is being broken. We should not do this if we consider the error temporary. - // Of course it could really be that our upstream is broken - if oe, ok := backendErr.(*net.OpError); ok { - // Note this keeps looping and trying until tryDuration is hit, at which point our client - // might be long gone... - if oe.Timeout() { - // Our upstream's upstream is probably messing up, continue with next selected - // host - which my be the *same* one as we don't set any uh.Fails. - continue - } - } - - timeout := host.FailTimeout - if timeout == 0 { - timeout = defaultFailTimeout - } - - atomic.AddInt32(&host.Fails, 1) - fails := atomic.LoadInt32(&host.Fails) - - go func(host *healthcheck.UpstreamHost, timeout time.Duration) { - time.Sleep(timeout) - // we may go negative here, should be rectified by the HC. - atomic.AddInt32(&host.Fails, -1) - if fails%failureCheck == 0 { // Kick off healthcheck on every third failure. - host.HealthCheckURL() - } - }(host, timeout) - } - - return dns.RcodeServerFailure, fmt.Errorf("%s: %s", errUnreachable, backendErr) - } -} - -func (p Proxy) match(state request.Request) (u Upstream) { - if p.Upstreams == nil { - return nil - } - - longestMatch := 0 - for _, upstream := range *p.Upstreams { - from := upstream.From() - - if !plugin.Name(from).Matches(state.Name()) || !upstream.IsAllowedDomain(state.Name()) { - continue - } - - if lf := len(from); lf > longestMatch { - longestMatch = lf - u = upstream - } - } - return u - -} - -// Name implements the Handler interface. -func (p Proxy) Name() string { return "proxy" } - -const ( - defaultFailTimeout = 2 * time.Second - defaultTimeout = 5 * time.Second - failureCheck = 3 -) |