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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 apiserver
import (
"bytes"
"compress/gzip"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/http/httputil"
"net/url"
"path"
"strings"
"time"
"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
"github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
"github.com/GoogleCloudPlatform/kubernetes/pkg/httplog"
"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
"github.com/golang/glog"
"golang.org/x/net/html"
)
// tagsToAttrs states which attributes of which tags require URL substitution.
// Sources: http://www.w3.org/TR/REC-html40/index/attributes.html
// http://www.w3.org/html/wg/drafts/html/master/index.html#attributes-1
var tagsToAttrs = map[string]util.StringSet{
"a": util.NewStringSet("href"),
"applet": util.NewStringSet("codebase"),
"area": util.NewStringSet("href"),
"audio": util.NewStringSet("src"),
"base": util.NewStringSet("href"),
"blockquote": util.NewStringSet("cite"),
"body": util.NewStringSet("background"),
"button": util.NewStringSet("formaction"),
"command": util.NewStringSet("icon"),
"del": util.NewStringSet("cite"),
"embed": util.NewStringSet("src"),
"form": util.NewStringSet("action"),
"frame": util.NewStringSet("longdesc", "src"),
"head": util.NewStringSet("profile"),
"html": util.NewStringSet("manifest"),
"iframe": util.NewStringSet("longdesc", "src"),
"img": util.NewStringSet("longdesc", "src", "usemap"),
"input": util.NewStringSet("src", "usemap", "formaction"),
"ins": util.NewStringSet("cite"),
"link": util.NewStringSet("href"),
"object": util.NewStringSet("classid", "codebase", "data", "usemap"),
"q": util.NewStringSet("cite"),
"script": util.NewStringSet("src"),
"source": util.NewStringSet("src"),
"video": util.NewStringSet("poster", "src"),
// TODO: css URLs hidden in style elements.
}
// ProxyHandler provides a http.Handler which will proxy traffic to locations
// specified by items implementing Redirector.
type ProxyHandler struct {
prefix string
storage map[string]RESTStorage
codec runtime.Codec
}
func (r *ProxyHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
namespace, kind, parts, err := KindAndNamespace(req)
if err != nil {
notFound(w, req)
return
}
ctx := api.WithNamespace(api.NewContext(), namespace)
if len(parts) < 2 {
notFound(w, req)
return
}
id := parts[1]
rest := ""
if len(parts) > 2 {
proxyParts := parts[2:]
rest = strings.Join(proxyParts, "/")
if strings.HasSuffix(req.URL.Path, "/") {
// The original path had a trailing slash, which has been stripped
// by KindAndNamespace(). We should add it back because some
// servers (like etcd) require it.
rest = rest + "/"
}
}
storage, ok := r.storage[kind]
if !ok {
httplog.LogOf(req, w).Addf("'%v' has no storage object", kind)
notFound(w, req)
return
}
redirector, ok := storage.(Redirector)
if !ok {
httplog.LogOf(req, w).Addf("'%v' is not a redirector", kind)
errorJSON(errors.NewMethodNotSupported(kind, "proxy"), r.codec, w)
return
}
location, err := redirector.ResourceLocation(ctx, id)
if err != nil {
httplog.LogOf(req, w).Addf("Error getting ResourceLocation: %v", err)
status := errToAPIStatus(err)
writeJSON(status.Code, r.codec, status, w)
return
}
if location == "" {
httplog.LogOf(req, w).Addf("ResourceLocation for %v returned ''", id)
notFound(w, req)
return
}
destURL, err := url.Parse(location)
if err != nil {
status := errToAPIStatus(err)
writeJSON(status.Code, r.codec, status, w)
return
}
if destURL.Scheme == "" {
// If no scheme was present in location, url.Parse sometimes mistakes
// hosts for paths.
destURL.Host = location
}
destURL.Path = rest
destURL.RawQuery = req.URL.RawQuery
newReq, err := http.NewRequest(req.Method, destURL.String(), req.Body)
if err != nil {
status := errToAPIStatus(err)
writeJSON(status.Code, r.codec, status, w)
notFound(w, req)
return
}
newReq.Header = req.Header
proxy := httputil.NewSingleHostReverseProxy(&url.URL{Scheme: "http", Host: destURL.Host})
proxy.Transport = &proxyTransport{
proxyScheme: req.URL.Scheme,
proxyHost: req.URL.Host,
proxyPathPrepend: path.Join(r.prefix, "ns", namespace, kind, id),
}
proxy.FlushInterval = 200 * time.Millisecond
proxy.ServeHTTP(w, newReq)
}
type proxyTransport struct {
proxyScheme string
proxyHost string
proxyPathPrepend string
}
func (t *proxyTransport) RoundTrip(req *http.Request) (*http.Response, error) {
// Add reverse proxy headers.
req.Header.Set("X-Forwarded-Uri", t.proxyPathPrepend+req.URL.Path)
req.Header.Set("X-Forwarded-Host", t.proxyHost)
req.Header.Set("X-Forwarded-Proto", t.proxyScheme)
resp, err := http.DefaultTransport.RoundTrip(req)
if err != nil {
message := fmt.Sprintf("Error: '%s'\nTrying to reach: '%v'", err.Error(), req.URL.String())
resp = &http.Response{
StatusCode: http.StatusServiceUnavailable,
Body: ioutil.NopCloser(strings.NewReader(message)),
}
return resp, nil
}
cType := resp.Header.Get("Content-Type")
cType = strings.TrimSpace(strings.SplitN(cType, ";", 2)[0])
if cType != "text/html" {
// Do nothing, simply pass through
return resp, nil
}
return t.fixLinks(req, resp)
}
// updateURLs checks and updates any of n's attributes that are listed in tagsToAttrs.
// Any URLs found are, if they're relative, updated with the necessary changes to make
// a visit to that URL also go through the proxy.
// sourceURL is the URL of the page which we're currently on; it's required to make
// relative links work.
func (t *proxyTransport) updateURLs(n *html.Node, sourceURL *url.URL) {
if n.Type != html.ElementNode {
return
}
attrs, ok := tagsToAttrs[n.Data]
if !ok {
return
}
for i, attr := range n.Attr {
if !attrs.Has(attr.Key) {
continue
}
url, err := url.Parse(attr.Val)
if err != nil {
continue
}
// Is this URL relative?
if url.Host == "" {
url.Scheme = t.proxyScheme
url.Host = t.proxyHost
url.Path = path.Join(t.proxyPathPrepend, path.Dir(sourceURL.Path), url.Path, "/")
n.Attr[i].Val = url.String()
} else if url.Host == sourceURL.Host {
url.Scheme = t.proxyScheme
url.Host = t.proxyHost
url.Path = path.Join(t.proxyPathPrepend, url.Path)
n.Attr[i].Val = url.String()
}
}
}
// scan recursively calls f for every n and every subnode of n.
func (t *proxyTransport) scan(n *html.Node, f func(*html.Node)) {
f(n)
for c := n.FirstChild; c != nil; c = c.NextSibling {
t.scan(c, f)
}
}
// fixLinks modifies links in an HTML file such that they will be redirected through the proxy if needed.
func (t *proxyTransport) fixLinks(req *http.Request, resp *http.Response) (*http.Response, error) {
origBody := resp.Body
defer origBody.Close()
newContent := &bytes.Buffer{}
var reader io.Reader = origBody
var writer io.Writer = newContent
encoding := resp.Header.Get("Content-Encoding")
switch encoding {
case "gzip":
var err error
reader, err = gzip.NewReader(reader)
if err != nil {
return nil, fmt.Errorf("errorf making gzip reader: %v", err)
}
gzw := gzip.NewWriter(writer)
defer gzw.Close()
writer = gzw
// TODO: support flate, other encodings.
case "":
// This is fine
default:
// Some encoding we don't understand-- don't try to parse this
glog.Errorf("Proxy encountered encoding %v for text/html; can't understand this so not fixing links.", encoding)
return resp, nil
}
doc, err := html.Parse(reader)
if err != nil {
glog.Errorf("Parse failed: %v", err)
return resp, err
}
t.scan(doc, func(n *html.Node) { t.updateURLs(n, req.URL) })
if err := html.Render(writer, doc); err != nil {
glog.Errorf("Failed to render: %v", err)
}
resp.Body = ioutil.NopCloser(newContent)
// Update header node with new content-length
// TODO: Remove any hash/signature headers here?
resp.Header.Del("Content-Length")
resp.ContentLength = int64(newContent.Len())
return resp, err
}
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