/
server.go
313 lines (283 loc) · 8.47 KB
/
server.go
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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package dl
import (
"context"
"crypto/hmac"
"crypto/md5"
"encoding/json"
"fmt"
"html"
"io"
"log"
"net/http"
"strings"
"sync"
"time"
"cloud.google.com/go/datastore"
"golang.org/x/website/internal/env"
"golang.org/x/website/internal/memcache"
)
type server struct {
datastore *datastore.Client
memcache *memcache.CodecClient
}
func RegisterHandlers(mux *http.ServeMux, dc *datastore.Client, mc *memcache.Client) {
s := server{dc, mc.WithCodec(memcache.Gob)}
mux.HandleFunc("/dl", s.getHandler)
mux.HandleFunc("/dl/", s.getHandler) // also serves listHandler
mux.HandleFunc("/dl/upload", s.uploadHandler)
// NOTE(cbro): this only needs to be run once per project,
// and should be behind an admin login.
// TODO(cbro): move into a locally-run program? or remove?
// mux.HandleFunc("/dl/init", initHandler)
}
// rootKey is the ancestor of all File entities.
var rootKey = datastore.NameKey("FileRoot", "root", nil)
func (h server) listHandler(w http.ResponseWriter, r *http.Request) {
if r.Method != "GET" && r.Method != "OPTIONS" {
http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
return
}
ctx := r.Context()
d := listTemplateData{
GoogleCN: googleCN(r),
}
if err := h.memcache.Get(ctx, cacheKey, &d); err != nil {
if err != memcache.ErrCacheMiss {
log.Printf("ERROR cache get error: %v", err)
// NOTE(cbro): continue to hit datastore if the memcache is down.
}
var fs []File
q := datastore.NewQuery("File").Ancestor(rootKey)
if _, err := h.datastore.GetAll(ctx, q, &fs); err != nil {
log.Printf("ERROR error listing: %v", err)
http.Error(w, "Could not get download page. Try again in a few minutes.", 500)
return
}
d.Stable, d.Unstable, d.Archive = filesToReleases(fs)
if len(d.Stable) > 0 {
d.Featured = filesToFeatured(d.Stable[0].Files)
}
item := &memcache.Item{Key: cacheKey, Object: &d, Expiration: cacheDuration}
if err := h.memcache.Set(ctx, item); err != nil {
log.Printf("ERROR cache set error: %v", err)
}
}
if r.URL.Query().Get("mode") == "json" {
serveJSON(w, r, d)
return
}
if err := listTemplate.ExecuteTemplate(w, "root", d); err != nil {
log.Printf("ERROR executing template: %v", err)
}
}
// serveJSON serves a JSON representation of d. It assumes that requests are
// limited to GET and OPTIONS, the latter used for CORS requests, which this
// endpoint supports.
func serveJSON(w http.ResponseWriter, r *http.Request, d listTemplateData) {
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Allow-Methods", "GET, OPTIONS")
if r.Method == "OPTIONS" {
// Likely a CORS preflight request.
w.WriteHeader(http.StatusNoContent)
return
}
var releases []Release
switch r.URL.Query().Get("include") {
case "all":
releases = append(append(d.Stable, d.Archive...), d.Unstable...)
default:
releases = d.Stable
}
w.Header().Set("Content-Type", "application/json")
enc := json.NewEncoder(w)
enc.SetIndent("", " ")
if err := enc.Encode(releases); err != nil {
log.Printf("ERROR rendering JSON for releases: %v", err)
}
}
// googleCN reports whether request r is considered
// to be served from golang.google.cn.
// TODO: This is duplicated within internal/proxy. Move to a common location.
func googleCN(r *http.Request) bool {
if r.FormValue("googlecn") != "" {
return true
}
if strings.HasSuffix(r.Host, ".cn") {
return true
}
if !env.CheckCountry() {
return false
}
switch r.Header.Get("X-Appengine-Country") {
case "", "ZZ", "CN":
return true
}
return false
}
func (h server) uploadHandler(w http.ResponseWriter, r *http.Request) {
if r.Method != "POST" {
http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
return
}
ctx := r.Context()
// Authenticate using a user token (same as gomote).
user := r.FormValue("user")
if !validUser(user) {
http.Error(w, "bad user", http.StatusForbidden)
return
}
if r.FormValue("key") != h.userKey(ctx, user) {
http.Error(w, "bad key", http.StatusForbidden)
return
}
var f File
defer r.Body.Close()
if err := json.NewDecoder(r.Body).Decode(&f); err != nil {
log.Printf("ERROR decoding upload JSON: %v", err)
http.Error(w, "Something broke", http.StatusInternalServerError)
return
}
if f.Filename == "" {
http.Error(w, "Must provide Filename", http.StatusBadRequest)
return
}
if f.Uploaded.IsZero() {
f.Uploaded = time.Now()
}
k := datastore.NameKey("File", f.Filename, rootKey)
if _, err := h.datastore.Put(ctx, k, &f); err != nil {
log.Printf("ERROR File entity: %v", err)
http.Error(w, "could not put File entity", http.StatusInternalServerError)
return
}
if err := h.memcache.Delete(ctx, cacheKey); err != nil {
log.Printf("ERROR delete error: %v", err)
}
io.WriteString(w, "OK")
}
func (h server) getHandler(w http.ResponseWriter, r *http.Request) {
isGoGet := (r.Method == "GET" || r.Method == "HEAD") && r.FormValue("go-get") == "1"
// For go get, we need to serve the same meta tags at /dl for cmd/go to
// validate against the import path.
if r.URL.Path == "/dl" && isGoGet {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
fmt.Fprintf(w, `<!DOCTYPE html><html><head>
<meta name="go-import" content="golang.org/dl git https://go.googlesource.com/dl">
</head></html>`)
return
}
if r.URL.Path == "/dl" {
http.Redirect(w, r, "/dl/", http.StatusFound)
return
}
name := strings.TrimPrefix(r.URL.Path, "/dl/")
var redirectURL string
switch {
case name == "":
h.listHandler(w, r)
return
case fileRe.MatchString(name):
// This is a /dl/{file} request to download a file. It's implemented by
// redirecting to another host, which serves the bytes more efficiently.
//
// The redirect target is an internal implementation detail and may change
// if there is a good reason to do so. Last time was in CL 76971 (in 2017).
const downloadBaseURL = "https://dl.google.com/go/"
http.Redirect(w, r, downloadBaseURL+name, http.StatusFound)
return
case name == "gotip":
redirectURL = "https://pkg.go.dev/golang.org/dl/gotip"
case goGetRe.MatchString(name):
redirectURL = "https://golang.org/dl/#" + name
default:
http.NotFound(w, r)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
if !isGoGet {
w.Header().Set("Location", redirectURL)
}
fmt.Fprintf(w, `<!DOCTYPE html>
<html>
<head>
<meta name="go-import" content="golang.org/dl git https://go.googlesource.com/dl">
<meta http-equiv="refresh" content="0; url=%s">
</head>
<body>
Nothing to see here; <a href="%s">move along</a>.
</body>
</html>
`, html.EscapeString(redirectURL), html.EscapeString(redirectURL))
}
func (h server) initHandler(w http.ResponseWriter, r *http.Request) {
var fileRoot struct {
Root string
}
ctx := r.Context()
k := rootKey
_, err := h.datastore.RunInTransaction(ctx, func(tx *datastore.Transaction) error {
err := tx.Get(k, &fileRoot)
if err != nil && err != datastore.ErrNoSuchEntity {
return err
}
_, err = tx.Put(k, &fileRoot)
return err
}, nil)
if err != nil {
http.Error(w, err.Error(), 500)
return
}
io.WriteString(w, "OK")
}
func (h server) userKey(c context.Context, user string) string {
hash := hmac.New(md5.New, []byte(h.secret(c)))
hash.Write([]byte("user-" + user))
return fmt.Sprintf("%x", hash.Sum(nil))
}
// Code below copied from x/build/app/key
var theKey struct {
sync.RWMutex
builderKey
}
type builderKey struct {
Secret string
}
func (k *builderKey) Key() *datastore.Key {
return datastore.NameKey("BuilderKey", "root", nil)
}
func (h server) secret(ctx context.Context) string {
// check with rlock
theKey.RLock()
k := theKey.Secret
theKey.RUnlock()
if k != "" {
return k
}
// prepare to fill; check with lock and keep lock
theKey.Lock()
defer theKey.Unlock()
if theKey.Secret != "" {
return theKey.Secret
}
// fill
if err := h.datastore.Get(ctx, theKey.Key(), &theKey.builderKey); err != nil {
if err == datastore.ErrNoSuchEntity {
// If the key is not stored in datastore, write it.
// This only happens at the beginning of a new deployment.
// The code is left here for SDK use and in case a fresh
// deployment is ever needed. "gophers rule" is not the
// real key.
if env.RequireDLSecretKey() {
panic("lost key from datastore")
}
theKey.Secret = "gophers rule"
h.datastore.Put(ctx, theKey.Key(), &theKey.builderKey)
return theKey.Secret
}
panic("cannot load builder key: " + err.Error())
}
return theKey.Secret
}