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proxy.go
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proxy.go
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/*
Copyright 2014 Google Inc. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package rest
import (
"crypto/tls"
"fmt"
"io"
"net"
"net/http"
"net/http/httputil"
"net/url"
"strings"
"sync"
"time"
"github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
"github.com/GoogleCloudPlatform/kubernetes/pkg/util/httpstream"
"github.com/GoogleCloudPlatform/kubernetes/pkg/util/proxy"
"github.com/GoogleCloudPlatform/kubernetes/third_party/golang/netutil"
"github.com/golang/glog"
)
// UpgradeAwareProxyHandler is a handler for proxy requests that may require an upgrade
type UpgradeAwareProxyHandler struct {
UpgradeRequired bool
Location *url.URL
Transport http.RoundTripper
FlushInterval time.Duration
err error
}
const defaultFlushInterval = 200 * time.Millisecond
// NewUpgradeAwareProxyHandler creates a new proxy handler with a default flush interval
func NewUpgradeAwareProxyHandler(location *url.URL, transport http.RoundTripper, upgradeRequired bool) *UpgradeAwareProxyHandler {
return &UpgradeAwareProxyHandler{
Location: location,
Transport: transport,
UpgradeRequired: upgradeRequired,
FlushInterval: defaultFlushInterval,
}
}
// RequestError returns an error that occurred while handling request
func (h *UpgradeAwareProxyHandler) RequestError() error {
return h.err
}
// ServeHTTP handles the proxy request
func (h *UpgradeAwareProxyHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
h.err = nil
if len(h.Location.Scheme) == 0 {
h.Location.Scheme = "http"
}
if h.tryUpgrade(w, req) {
return
}
if h.UpgradeRequired {
h.err = errors.NewBadRequest("Upgrade request required")
return
}
if h.Transport == nil {
h.Transport = h.defaultProxyTransport(req.URL)
}
loc := *h.Location
loc.RawQuery = req.URL.RawQuery
newReq, err := http.NewRequest(req.Method, loc.String(), req.Body)
if err != nil {
h.err = err
return
}
newReq.Header = req.Header
proxy := httputil.NewSingleHostReverseProxy(&url.URL{Scheme: h.Location.Scheme, Host: h.Location.Host})
proxy.Transport = h.Transport
proxy.FlushInterval = h.FlushInterval
proxy.ServeHTTP(w, newReq)
}
// tryUpgrade returns true if the request was handled.
func (h *UpgradeAwareProxyHandler) tryUpgrade(w http.ResponseWriter, req *http.Request) bool {
if !httpstream.IsUpgradeRequest(req) {
return false
}
backendConn, err := h.dialURL()
if err != nil {
h.err = err
return true
}
defer backendConn.Close()
requestHijackedConn, _, err := w.(http.Hijacker).Hijack()
if err != nil {
h.err = err
return true
}
defer requestHijackedConn.Close()
newReq, err := http.NewRequest(req.Method, h.Location.String(), req.Body)
if err != nil {
h.err = err
return true
}
newReq.Header = req.Header
if err = newReq.Write(backendConn); err != nil {
h.err = err
return true
}
wg := &sync.WaitGroup{}
wg.Add(2)
go func() {
_, err := io.Copy(backendConn, requestHijackedConn)
if err != nil && !strings.Contains(err.Error(), "use of closed network connection") {
glog.Errorf("Error proxying data from client to backend: %v", err)
}
wg.Done()
}()
go func() {
_, err := io.Copy(requestHijackedConn, backendConn)
if err != nil && !strings.Contains(err.Error(), "use of closed network connection") {
glog.Errorf("Error proxying data from backend to client: %v", err)
}
wg.Done()
}()
wg.Wait()
return true
}
func (h *UpgradeAwareProxyHandler) dialURL() (net.Conn, error) {
dialAddr := netutil.CanonicalAddr(h.Location)
switch h.Location.Scheme {
case "http":
return net.Dial("tcp", dialAddr)
case "https":
// Get the tls config from the transport if we recognize it
var tlsConfig *tls.Config
if h.Transport != nil {
httpTransport, ok := h.Transport.(*http.Transport)
if ok {
tlsConfig = httpTransport.TLSClientConfig
}
}
// Dial
tlsConn, err := tls.Dial("tcp", dialAddr, tlsConfig)
if err != nil {
return nil, err
}
// Verify
host, _, _ := net.SplitHostPort(dialAddr)
if err := tlsConn.VerifyHostname(host); err != nil {
tlsConn.Close()
return nil, err
}
return tlsConn, nil
default:
return nil, fmt.Errorf("Unknown scheme: %s", h.Location.Scheme)
}
}
func (h *UpgradeAwareProxyHandler) defaultProxyTransport(url *url.URL) http.RoundTripper {
scheme := url.Scheme
host := url.Host
pathPrepend := strings.TrimRight(url.Path, h.Location.Path)
return &proxy.Transport{
Scheme: scheme,
Host: host,
PathPrepend: pathPrepend,
}
}