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// Copyright 2013 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 redirect provides hooks to register HTTP handlers that redirect old
// godoc paths to their new equivalents and assist in accessing the issue
// tracker, wiki, code review system, etc.
package redirect // import "golang.org/x/website/internal/redirect"
import (
"context"
_ "embed"
"fmt"
"net/http"
"regexp"
"strconv"
"strings"
"sync"
"time"
"golang.org/x/net/context/ctxhttp"
"golang.org/x/website/internal/backport/html/template"
)
// Register registers HTTP handlers that redirect old godoc paths to their new
// equivalents and assist in accessing the issue tracker, wiki, code review
// system, etc.
func Register(mux *http.ServeMux) {
handlePathRedirects(mux, pkgRedirects, "/pkg/")
handlePathRedirects(mux, cmdRedirects, "/cmd/")
for prefix, redirect := range prefixHelpers {
p := "/" + prefix + "/"
mux.Handle(p, PrefixHandler(p, redirect))
}
for path, redirect := range redirects {
mux.Handle(path, Handler(redirect))
}
for path, redirect := range blogRedirects {
mux.Handle("/blog"+path, Handler("/blog/"+redirect))
}
for _, path := range newIssueRedirects {
mux.Handle(path, newIssueHandler(path))
}
// NB: /src/pkg (sans trailing slash) is the index of packages.
mux.HandleFunc("/src/pkg/", srcPkgHandler)
mux.HandleFunc("/cl/", clHandler)
mux.HandleFunc("/change/", changeHandler)
mux.HandleFunc("/design/", designHandler)
}
func handlePathRedirects(mux *http.ServeMux, redirects map[string]string, prefix string) {
for source, target := range redirects {
h := Handler(prefix + target + "/")
p := prefix + source
mux.Handle(p, h)
mux.Handle(p+"/", h)
}
}
// Packages that were renamed between r60 and go1.
var pkgRedirects = map[string]string{
"asn1": "encoding/asn1",
"big": "math/big",
"cmath": "math/cmplx",
"csv": "encoding/csv",
"exec": "os/exec",
"exp/template/html": "html/template",
"gob": "encoding/gob",
"http": "net/http",
"http/cgi": "net/http/cgi",
"http/fcgi": "net/http/fcgi",
"http/httptest": "net/http/httptest",
"http/pprof": "net/http/pprof",
"json": "encoding/json",
"mail": "net/mail",
"rand": "math/rand",
"rpc": "net/rpc",
"rpc/jsonrpc": "net/rpc/jsonrpc",
"scanner": "text/scanner",
"smtp": "net/smtp",
"tabwriter": "text/tabwriter",
"template": "text/template",
"template/parse": "text/template/parse",
"url": "net/url",
"utf16": "unicode/utf16",
"utf8": "unicode/utf8",
"xml": "encoding/xml",
}
// Commands that were renamed between r60 and go1.
var cmdRedirects = map[string]string{
"gofix": "fix",
"goinstall": "go",
"gopack": "pack",
"gotest": "go",
"govet": "vet",
"goyacc": "yacc",
}
var redirects = map[string]string{
"/build": "https://build.golang.org",
"/change": "https://go.googlesource.com/go",
"/cl": "https://go-review.googlesource.com",
"/cmd/godoc/": "https://pkg.go.dev/golang.org/x/tools/cmd/godoc",
"/issue": "https://github.com/golang/go/issues",
"/issues": "https://github.com/golang/go/issues",
"/design": "https://go.googlesource.com/proposal/+/master/design",
// In Go 1.2 the references page is part of /doc/.
"/ref": "/doc/#references",
// This next rule clobbers /ref/spec and /ref/mem.
// TODO(adg): figure out what to do here, if anything.
// "/ref/": "/doc/#references",
// Be nice to people who are looking in the wrong place.
"/pkg/C/": "/cmd/cgo/",
"/doc/mem": "/ref/mem",
"/doc/spec": "/ref/spec",
"/wiki": "https://github.com/golang/go/wiki",
"/doc/articles/c_go_cgo.html": "/blog/c-go-cgo",
"/doc/articles/concurrency_patterns.html": "/blog/go-concurrency-patterns-timing-out-and",
"/doc/articles/defer_panic_recover.html": "/blog/defer-panic-and-recover",
"/doc/articles/error_handling.html": "/blog/error-handling-and-go",
"/doc/articles/gobs_of_data.html": "/blog/gobs-of-data",
"/doc/articles/godoc_documenting_go_code.html": "/blog/godoc-documenting-go-code",
"/doc/articles/gos_declaration_syntax.html": "/blog/gos-declaration-syntax",
"/doc/articles/image_draw.html": "/blog/go-imagedraw-package",
"/doc/articles/image_package.html": "/blog/go-image-package",
"/doc/articles/json_and_go.html": "/blog/json-and-go",
"/doc/articles/json_rpc_tale_of_interfaces.html": "/blog/json-rpc-tale-of-interfaces",
"/doc/articles/laws_of_reflection.html": "/blog/laws-of-reflection",
"/doc/articles/slices_usage_and_internals.html": "/blog/go-slices-usage-and-internals",
"/doc/go_for_cpp_programmers.html": "/wiki/GoForCPPProgrammers",
"/doc/go_tutorial.html": "/tour",
}
var newIssueRedirects = [...]string{
"/issue/new",
"/issue/new/",
"/issues/new",
"/issues/new/",
}
var prefixHelpers = map[string]string{
"issue": "https://github.com/golang/go/issues/",
"issues": "https://github.com/golang/go/issues/",
"wiki": "https://github.com/golang/go/wiki/",
}
func Handler(target string) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
url := target
if qs := r.URL.RawQuery; qs != "" {
url += "?" + qs
}
http.Redirect(w, r, url, http.StatusMovedPermanently)
})
}
var validID = regexp.MustCompile(`^[A-Za-z0-9\-._]*/?$`)
func PrefixHandler(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 := baseURL + id
http.Redirect(w, r, target, http.StatusFound)
})
}
// newIssueHandler handles /issue/new and similar requests,
// redirecting to a "New Issue" UI in the main Go issue tracker.
func newIssueHandler(source string) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.URL.Path != source {
http.Error(w, "Not found", http.StatusNotFound)
return
}
target := "https://github.com/golang/go/issues/new"
if qs := r.URL.RawQuery; qs == "" {
// There are many "go.dev/issue/new" links that led to a good experience
// of reporting an issue when there was a single issue template.
// As of CL 366736 there are many templates, and the same URL results
// in an empty new issue UI, which defeats having any templates.
//
// Handle this case specially and redirect to "/new/choose" instead,
// at least until GitHub changes their behavior. See go.dev/issue/29839.
target += "/choose"
} else {
// Query options like ?title=...&body=...&labels=... only work on /new.
target += "?" + qs
}
http.Redirect(w, r, target, http.StatusFound)
})
}
// Redirect requests from the old "/src/pkg/foo" to the new "/src/foo".
// See https://golang.org/s/go14nopkg
func srcPkgHandler(w http.ResponseWriter, r *http.Request) {
r.URL.Path = "/src/" + r.URL.Path[len("/src/pkg/"):]
http.Redirect(w, r, r.URL.String(), http.StatusMovedPermanently)
}
func clHandler(w http.ResponseWriter, r *http.Request) {
const prefix = "/cl/"
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):]
// support /cl/152700045/, which is used in commit 0edafefc36.
id = strings.TrimSuffix(id, "/")
if !validID.MatchString(id) {
http.Error(w, "Not found", http.StatusNotFound)
return
}
target := ""
if n, err := strconv.Atoi(id); err == nil && isRietveldCL(n) {
// Issue 28836: if this Rietveld CL happens to
// also be a Gerrit CL, render a disambiguation HTML
// page with two links instead. We need to make a
// Gerrit API call to figure that out, but we cache
// known Gerrit CLs so it's done at most once per CL.
if ok, err := isGerritCL(r.Context(), n); err == nil && ok {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
clDisambiguationHTML.Execute(w, n)
return
}
target = "https://codereview.appspot.com/" + id
} else {
target = "https://go-review.googlesource.com/" + id
}
http.Redirect(w, r, target, http.StatusFound)
}
var clDisambiguationHTML = template.Must(template.New("").Parse(`<!DOCTYPE html>
<html lang="en">
<head>
<title>Go CL {{.}} Disambiguation</title>
<meta name="viewport" content="width=device-width">
</head>
<body>
CL number {{.}} exists in both Gerrit (the current code review system)
and Rietveld (the previous code review system). Please make a choice:
<ul>
<li><a href="https://go-review.googlesource.com/{{.}}">Gerrit CL {{.}}</a></li>
<li><a href="https://codereview.appspot.com/{{.}}">Rietveld CL {{.}}</a></li>
</ul>
</body>
</html>`))
// isGerritCL reports whether a Gerrit CL with the specified numeric change ID (e.g., "4247")
// is known to exist by querying the Gerrit API at https://go-review.googlesource.com.
// isGerritCL uses gerritCLCache as a cache of Gerrit CL IDs that exist.
func isGerritCL(ctx context.Context, id int) (bool, error) {
// Check cache first.
gerritCLCache.Lock()
ok := gerritCLCache.exist[id]
gerritCLCache.Unlock()
if ok {
return true, nil
}
// Query the Gerrit API Get Change endpoint, as documented at
// https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#get-change.
ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
defer cancel()
resp, err := ctxhttp.Get(ctx, nil, fmt.Sprintf("https://go-review.googlesource.com/changes/%d", id))
if err != nil {
return false, err
}
resp.Body.Close()
switch resp.StatusCode {
case http.StatusOK:
// A Gerrit CL with this ID exists. Add it to cache.
gerritCLCache.Lock()
gerritCLCache.exist[id] = true
gerritCLCache.Unlock()
return true, nil
case http.StatusNotFound:
// A Gerrit CL with this ID doesn't exist. It may get created in the future.
return false, nil
default:
return false, fmt.Errorf("unexpected status code: %v", resp.Status)
}
}
var gerritCLCache = struct {
sync.Mutex
exist map[int]bool // exist is a set of Gerrit CL IDs that are known to exist.
}{exist: make(map[int]bool)}
//go:embed hg-git-mapping.bin
var hgGitMappingBin []byte
var changeMap = hashMap(hgGitMappingBin)
func changeHandler(w http.ResponseWriter, r *http.Request) {
const prefix = "/change/"
if p := r.URL.Path; p == prefix {
// redirect /prefix/ to /prefix
http.Redirect(w, r, p[:len(p)-1], http.StatusFound)
return
}
hash := r.URL.Path[len(prefix):]
target := "https://go.googlesource.com/go/+/" + hash
if git := changeMap.Lookup(hash); git > 0 {
target = fmt.Sprintf("https://go.googlesource.com/%v/+/%v", git.Repo(), git.Hash())
}
http.Redirect(w, r, target, http.StatusFound)
}
func designHandler(w http.ResponseWriter, r *http.Request) {
const prefix = "/design/"
if p := r.URL.Path; p == prefix {
// redirect /prefix/ to /prefix
http.Redirect(w, r, p[:len(p)-1], http.StatusFound)
return
}
name := r.URL.Path[len(prefix):]
target := "https://go.googlesource.com/proposal/+/master/design/" + name + ".md"
http.Redirect(w, r, target, http.StatusFound)
}