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, 8 insertions, 13 deletions

diff --git a/middleware/proxy/dns.go b/middleware/proxy/dns.go
index 51633c268..4fde48e40 100644
--- a/middleware/proxy/dns.go
+++ b/middleware/proxy/dns.go
@@ -12,23 +12,20 @@ import (
 
 type dnsEx struct {
 	Timeout time.Duration
-	Address string // address/name of this upstream
-
-	group *singleflight.Group
+	group   *singleflight.Group
 }
 
-func newDNSEx(address string) *dnsEx {
-	return &dnsEx{Address: address, group: new(singleflight.Group), Timeout: defaultTimeout * time.Second}
+func newDNSEx() *dnsEx {
+	return &dnsEx{group: new(singleflight.Group), Timeout: defaultTimeout * time.Second}
 }
 
-func (d *dnsEx) OnStartup() error             { return nil }
-func (d *dnsEx) OnShutdown() error            { return nil }
-func (d *dnsEx) SetUpstream(u Upstream) error { return nil }
-func (d *dnsEx) Protocol() protocol           { return dnsProto }
+func (g *dnsEx) Protocol() string          { return "dns" }
+func (d *dnsEx) OnShutdown(p *Proxy) error { return nil }
+func (d *dnsEx) OnStartup(p *Proxy) error  { return nil }
 
 // Exchange implements the Exchanger interface.
-func (d *dnsEx) Exchange(state request.Request) (*dns.Msg, error) {
-	co, err := net.DialTimeout(state.Proto(), d.Address, d.Timeout)
+func (d *dnsEx) Exchange(addr string, state request.Request) (*dns.Msg, error) {
+	co, err := net.DialTimeout(state.Proto(), addr, d.Timeout)
 	if err != nil {
 		return nil, err
 	}
@@ -101,5 +98,3 @@ func exchange(m *dns.Msg, co net.Conn) (dns.Msg, error) {
 	}
 	return *r, err
 }
-
-const dnsProto protocol = "dns"