middleware/proxy: absorb httpproxy (#481)

* middleware/proxy: absorb httpproxy

Move the httproxy into proxy. This adds and Exchanger interface which
is used to exchange the messages with the upstream.

The https_google upstream will re-resolve itself and update the upstream
hosts used every 300s.

* Remove and add TODO

1 files changed, 0 insertions, 45 deletions

diff --git a/middleware/httpproxy/proxy.go b/middleware/httpproxy/proxy.go
deleted file mode 100644
index 3ef638a8f..000000000
--- a/middleware/httpproxy/proxy.go
+++ /dev/null
@@ -1,45 +0,0 @@
-// Package httpproxy is middleware that proxies requests to a HTTPs server doing DNS.
-package httpproxy
-
-import (
-	"errors"
-	"time"
-
-	"github.com/miekg/coredns/middleware"
-	"github.com/miekg/coredns/request"
-
-	"github.com/miekg/dns"
-	"golang.org/x/net/context"
-)
-
-var errUnreachable = errors.New("unreachable backend")
-
-// Proxy represents a middleware instance that can proxy requests to HTTPS servers.
-type Proxy struct {
-	from string
-	e    Exchanger
-
-	Next middleware.Handler
-}
-
-// ServeDNS satisfies the middleware.Handler interface.
-func (p *Proxy) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
-	start := time.Now()
-	state := request.Request{W: w, Req: r}
-
-	reply, backendErr := p.e.Exchange(state)
-
-	if backendErr == nil && reply != nil {
-		state.SizeAndDo(reply)
-
-		w.WriteMsg(reply)
-		RequestDuration.WithLabelValues(p.from).Observe(float64(time.Since(start) / time.Millisecond))
-		return 0, nil
-	}
-	RequestDuration.WithLabelValues(p.from).Observe(float64(time.Since(start) / time.Millisecond))
-
-	return dns.RcodeServerFailure, errUnreachable
-}
-
-// Name implements the Handler interface.
-func (p Proxy) Name() string { return "httpproxy" }