/* 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" "fmt" "io/ioutil" "net/http" "net/http/httputil" "net/url" "path" "strings" "github.com/GoogleCloudPlatform/kubernetes/pkg/api" "github.com/GoogleCloudPlatform/kubernetes/pkg/httplog" "github.com/GoogleCloudPlatform/kubernetes/pkg/runtime" "github.com/GoogleCloudPlatform/kubernetes/pkg/util" "code.google.com/p/go.net/html" "github.com/golang/glog" ) // 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) { ctx := api.NewContext() parts := strings.SplitN(req.URL.Path, "/", 3) if len(parts) < 2 { notFound(w, req) return } resourceName := parts[0] id := parts[1] rest := "" if len(parts) == 3 { rest = parts[2] } storage, ok := r.storage[resourceName] if !ok { httplog.LogOf(req, w).Addf("'%v' has no storage object", resourceName) notFound(w, req) return } redirector, ok := storage.(Redirector) if !ok { httplog.LogOf(req, w).Addf("'%v' is not a redirector", resourceName) notFound(w, req) return } location, err := redirector.ResourceLocation(ctx, id) if err != nil { status := errToAPIStatus(err) writeJSON(status.Code, r.codec, status, w) return } destURL, err := url.Parse(location) if err != nil { status := errToAPIStatus(err) writeJSON(status.Code, r.codec, status, w) return } destURL.Path = rest destURL.RawQuery = req.URL.RawQuery newReq, err := http.NewRequest(req.Method, destURL.String(), req.Body) if err != nil { glog.Errorf("Failed to create request: %s", err) } 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, resourceName, id), } proxy.ServeHTTP(w, newReq) } type proxyTransport struct { proxyScheme string proxyHost string proxyPathPrepend string } func (t *proxyTransport) RoundTrip(req *http.Request) (*http.Response, error) { 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 } if resp.Header.Get("Content-Type") != "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) { defer resp.Body.Close() doc, err := html.Parse(resp.Body) if err != nil { glog.Errorf("Parse failed: %v", err) return resp, err } newContent := &bytes.Buffer{} t.scan(doc, func(n *html.Node) { t.updateURLs(n, req.URL) }) if err := html.Render(newContent, 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 }