// Copyright 2019 The gVisor Authors
//
// 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
//
// https://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.
// Server is the main gvisor.dev binary.
package main
import (
"flag"
"fmt"
"log"
"net/http"
"os"
"regexp"
"strings"
)
var redirects = map[string]string{
// GitHub redirects.
"/change": "https://github.com/google/gvisor",
"/issue": "https://github.com/google/gvisor/issues",
"/issue/new": "https://github.com/google/gvisor/issues/new",
"/pr": "https://github.com/google/gvisor/pulls",
// For links.
"/faq": "/docs/user_guide/faq/",
// From 2020-05-12 to 2020-06-30, the FAQ URL was uppercase. Redirect that
// back to maintain any links.
"/docs/user_guide/FAQ/": "/docs/user_guide/faq/",
// Redirects to compatibility docs.
"/c": "/docs/user_guide/compatibility/",
"/c/linux/amd64": "/docs/user_guide/compatibility/linux/amd64/",
// Redirect for old URLs.
"/docs/user_guide/compatibility/amd64/": "/docs/user_guide/compatibility/linux/amd64/",
"/docs/user_guide/compatibility/amd64": "/docs/user_guide/compatibility/linux/amd64/",
"/docs/user_guide/kubernetes/": "/docs/user_guide/quick_start/kubernetes/",
"/docs/user_guide/kubernetes": "/docs/user_guide/quick_start/kubernetes/",
"/docs/user_guide/oci/": "/docs/user_guide/quick_start/oci/",
"/docs/user_guide/oci": "/docs/user_guide/quick_start/oci/",
"/docs/user_guide/docker/": "/docs/user_guide/quick_start/docker/",
"/docs/user_guide/docker": "/docs/user_guide/quick_start/docker/",
// Deprecated, but links continue to work.
"/cl": "https://gvisor-review.googlesource.com",
}
var prefixHelpers = map[string]string{
"change": "https://github.com/google/gvisor/commit/%s",
"issue": "https://github.com/google/gvisor/issues/%s",
"pr": "https://github.com/google/gvisor/pull/%s",
// Redirects to compatibility docs.
"c/linux/amd64": "/docs/user_guide/compatibility/linux/amd64/#%s",
// Deprecated, but links continue to work.
"cl": "https://gvisor-review.googlesource.com/c/gvisor/+/%s",
}
var (
validID = regexp.MustCompile(`^[A-Za-z0-9-]*/?$`)
goGetHTML5 = `
Go-get`
)
// cronHandler wraps an http.Handler to check that the request is from the App
// Engine Cron service.
// See: https://cloud.google.com/appengine/docs/standard/go112/scheduling-jobs-with-cron-yaml#validating_cron_requests
func cronHandler(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Header.Get("X-Appengine-Cron") != "true" {
http.NotFound(w, r)
return
}
// Fallthrough.
h.ServeHTTP(w, r)
})
}
// wrappedHandler wraps an http.Handler.
//
// If the query parameters include go-get=1, then we redirect to a single
// static page that allows us to serve arbitrary Go packages.
func wrappedHandler(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
gg, ok := r.URL.Query()["go-get"]
if ok && len(gg) == 1 && gg[0] == "1" {
// Serve a trivial html page.
w.Write([]byte(goGetHTML5))
return
}
// Fallthrough.
h.ServeHTTP(w, r)
})
}
// redirectWithQuery redirects to the given target url preserving query parameters.
func redirectWithQuery(w http.ResponseWriter, r *http.Request, target string) {
url := target
if qs := r.URL.RawQuery; qs != "" {
url += "?" + qs
}
http.Redirect(w, r, url, http.StatusFound)
}
// hostRedirectHandler redirects the www. domain to the naked domain.
func hostRedirectHandler(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if strings.HasPrefix(r.Host, "www.") {
// Redirect to the naked domain.
r.URL.Scheme = "https" // Assume https.
r.URL.Host = r.Host[4:] // Remove the 'www.'
http.Redirect(w, r, r.URL.String(), http.StatusMovedPermanently)
return
}
if *projectID != "" && r.Host == *projectID+".appspot.com" && *customHost != "" {
// Redirect to the custom domain.
r.URL.Scheme = "https" // Assume https.
r.URL.Host = *customHost
http.Redirect(w, r, r.URL.String(), http.StatusMovedPermanently)
return
}
h.ServeHTTP(w, r)
})
}
// prefixRedirectHandler returns a handler that redirects to the given formated url.
func prefixRedirectHandler(prefix, baseURL string) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if p := r.URL.Path; p == prefix {
// Redirect /prefix/ to /prefix.
http.Redirect(w, r, p[:len(p)-1], http.StatusFound)
return
}
id := r.URL.Path[len(prefix):]
if !validID.MatchString(id) {
http.Error(w, "Not found", http.StatusNotFound)
return
}
target := fmt.Sprintf(baseURL, id)
redirectWithQuery(w, r, target)
})
}
// redirectHandler returns a handler that redirects to the given url.
func redirectHandler(target string) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
redirectWithQuery(w, r, target)
})
}
// redirectRedirects registers redirect http handlers.
func registerRedirects(mux *http.ServeMux) {
if mux == nil {
mux = http.DefaultServeMux
}
for prefix, baseURL := range prefixHelpers {
p := "/" + prefix + "/"
mux.Handle(p, hostRedirectHandler(wrappedHandler(prefixRedirectHandler(p, baseURL))))
}
for path, redirect := range redirects {
mux.Handle(path, hostRedirectHandler(wrappedHandler(redirectHandler(redirect))))
}
}
// registerStatic registers static file handlers
func registerStatic(mux *http.ServeMux, staticDir string) {
if mux == nil {
mux = http.DefaultServeMux
}
mux.Handle("/", hostRedirectHandler(wrappedHandler(http.FileServer(http.Dir(staticDir)))))
}
func envFlagString(name, def string) string {
if val := os.Getenv(name); val != "" {
return val
}
return def
}
var (
addr = flag.String("http", envFlagString("HTTP", ":"+envFlagString("PORT", "8080")), "HTTP service address")
staticDir = flag.String("static-dir", envFlagString("STATIC_DIR", "_site"), "static files directory")
// Uses the standard GOOGLE_CLOUD_PROJECT environment variable set by App Engine.
projectID = flag.String("project-id", envFlagString("GOOGLE_CLOUD_PROJECT", ""), "The App Engine project ID.")
customHost = flag.String("custom-domain", envFlagString("CUSTOM_DOMAIN", "gvisor.dev"), "The application's custom domain.")
)
func main() {
flag.Parse()
registerRedirects(nil)
registerStatic(nil, *staticDir)
log.Printf("Listening on %s...", *addr)
log.Fatal(http.ListenAndServe(*addr, nil))
}