Fix various bugs for "install" page (#23194)

## TLDR

* Fix the broken page / broken image problem when click "Install"
* Close #20089
* Fix the Password Hash Algorithm display problem for #22942
* Close #23183
* Close #23184

## Details

### The broken page / broken image problem when click "Install"
(Redirect failed after install gitea #23184)

Before: when click "install", all new requests will fail, because the
server has been restarted. Users just see a broken page with broken
images, sometimes the server is not ready but the user would have been
redirect to "/user/login" page, then the users see a new broken page
(connection refused or something wrong ...)

After: only check InstallLock=true for necessary handlers, and sleep for
a while before restarting the server, then the browser has enough time
to load the "post-install" page. And there is a script to check whether
"/user/login" is ready, the user will only be redirected to the login
page when the server is ready.

### During new instance setup make 'Gitea Base URL' filled from
window.location.origin #20089

If the "app_url" input contains `localhost` (the default value from
config), use current window's location href as the `app_url` (aka
ROOT_URL)

### Fix the Password Hash Algorithm display problem for "Provide the
ability to set password hash algorithm parameters #22942"

Before: the UI shows `pbkdf2$50000$50`

<details>

![image](https://user-images.githubusercontent.com/2114189/221917143-e1e54798-1698-4fee-a18d-00c48081fc39.png)

</details>

After: the UI shows `pbkdf2`

<details>

![image](https://user-images.githubusercontent.com/2114189/221916999-97a15be8-2ebb-4a01-bf93-dac18e354fcc.png)

</details>

### GET data: net::ERR_INVALID_URL #23183

Cause by empty `data:` in `<link rel="manifest"
href="data:{{.ManifestData}}">`

---------

Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

routers/install/install.go

@@ -59,11 +59,6 @@ func Init(ctx goctx.Context) func(next http.Handler) http.Handler {
 	dbTypeNames := getSupportedDbTypeNames()
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
-			if setting.InstallLock {
-				resp.Header().Add("Refresh", "1; url="+setting.AppURL+"user/login")
-				_ = rnd.HTML(resp, http.StatusOK, string(tplPostInstall), nil)
-				return
-			}
 			locale := middleware.Locale(resp, req)
 			startTime := time.Now()
 			ctx := context.Context{
@@ -93,6 +88,11 @@ func Init(ctx goctx.Context) func(next http.Handler) http.Handler {
 
 // Install render installation page
 func Install(ctx *context.Context) {
+	if setting.InstallLock {
+		InstallDone(ctx)
+		return
+	}
+
 	form := forms.InstallForm{}
 
 	// Database settings
@@ -162,7 +162,7 @@ func Install(ctx *context.Context) {
 	form.DefaultAllowCreateOrganization = setting.Service.DefaultAllowCreateOrganization
 	form.DefaultEnableTimetracking = setting.Service.DefaultEnableTimetracking
 	form.NoReplyAddress = setting.Service.NoReplyAddress
-	form.PasswordAlgorithm = setting.PasswordHashAlgo
+	form.PasswordAlgorithm = hash.ConfigHashAlgorithm(setting.PasswordHashAlgo)
 
 	middleware.AssignForm(form, ctx.Data)
 	ctx.HTML(http.StatusOK, tplInstall)
@@ -234,6 +234,11 @@ func checkDatabase(ctx *context.Context, form *forms.InstallForm) bool {
 
 // SubmitInstall response for submit install items
 func SubmitInstall(ctx *context.Context) {
+	if setting.InstallLock {
+		InstallDone(ctx)
+		return
+	}
+
 	var err error
 
 	form := *web.GetForm(ctx).(*forms.InstallForm)
@@ -277,7 +282,6 @@ func SubmitInstall(ctx *context.Context) {
 	setting.Database.Charset = form.Charset
 	setting.Database.Path = form.DbPath
 	setting.Database.LogSQL = !setting.IsProd
-	setting.PasswordHashAlgo = form.PasswordAlgorithm
 
 	if !checkDatabase(ctx, &form) {
 		return
@@ -499,6 +503,12 @@ func SubmitInstall(ctx *context.Context) {
 	}
 
 	if len(form.PasswordAlgorithm) > 0 {
+		var algorithm *hash.PasswordHashAlgorithm
+		setting.PasswordHashAlgo, algorithm = hash.SetDefaultPasswordHashAlgorithm(form.PasswordAlgorithm)
+		if algorithm == nil {
+			ctx.RenderWithErr(ctx.Tr("install.invalid_password_algorithm"), tplInstall, &form)
+			return
+		}
 		cfg.Section("security").Key("PASSWORD_HASH_ALGO").SetValue(form.PasswordAlgorithm)
 	}
 
@@ -571,18 +581,26 @@ func SubmitInstall(ctx *context.Context) {
 	}
 
 	log.Info("First-time run install finished!")
+	InstallDone(ctx)
 
-	ctx.Flash.Success(ctx.Tr("install.install_success"))
-
-	ctx.RespHeader().Add("Refresh", "1; url="+setting.AppURL+"user/login")
-	ctx.HTML(http.StatusOK, tplPostInstall)
-
-	// Now get the http.Server from this request and shut it down
-	// NB: This is not our hammerable graceful shutdown this is http.Server.Shutdown
-	srv := ctx.Value(http.ServerContextKey).(*http.Server)
 	go func() {
+		// Sleep for a while to make sure the user's browser has loaded the post-install page and its assets (images, css, js)
+		// What if this duration is not long enough? That's impossible -- if the user can't load the simple page in time, how could they install or use Gitea in the future ....
+		time.Sleep(3 * time.Second)
+
+		// Now get the http.Server from this request and shut it down
+		// NB: This is not our hammerable graceful shutdown this is http.Server.Shutdown
+		srv := ctx.Value(http.ServerContextKey).(*http.Server)
 		if err := srv.Shutdown(graceful.GetManager().HammerContext()); err != nil {
 			log.Error("Unable to shutdown the install server! Error: %v", err)
 		}
+
+		// After the HTTP server for "install" shuts down, the `runWeb()` will continue to run the "normal" server
 	}()
 }
+
+// InstallDone shows the "post-install" page, makes it easier to develop the page.
+// The name is not called as "PostInstall" to avoid misinterpretation as a handler for "POST /install"
+func InstallDone(ctx *context.Context) { //nolint
+	ctx.HTML(http.StatusOK, tplPostInstall)
+}

routers/install/routes.go

@@ -6,6 +6,7 @@ package install
 import (
 	goctx "context"
 	"fmt"
+	"html"
 	"net/http"
 	"path"
 
@@ -37,7 +38,7 @@ func installRecovery(ctx goctx.Context) func(next http.Handler) http.Handler {
 				// Why we need this? The first recover will try to render a beautiful
 				// error page for user, but the process can still panic again, then
 				// we have to just recover twice and send a simple error page that
-				// should not panic any more.
+				// should not panic anymore.
 				defer func() {
 					if err := recover(); err != nil {
 						combinedErr := fmt.Sprintf("PANIC: %v\n%s", err, log.Stack(2))
@@ -107,8 +108,9 @@ func Routes(ctx goctx.Context) *web.Route {
 
 	r.Use(installRecovery(ctx))
 	r.Use(Init(ctx))
-	r.Get("/", Install)
+	r.Get("/", Install) // it must be on the root, because the "install.js" use the window.location to replace the "localhost" AppURL
 	r.Post("/", web.Bind(forms.InstallForm{}), SubmitInstall)
+	r.Get("/post-install", InstallDone)
 	r.Get("/api/healthz", healthcheck.Check)
 
 	r.NotFound(web.Wrap(installNotFound))
@@ -116,5 +118,10 @@ func Routes(ctx goctx.Context) *web.Route {
 }
 
 func installNotFound(w http.ResponseWriter, req *http.Request) {
-	http.Redirect(w, req, setting.AppURL, http.StatusFound)
+	w.Header().Add("Content-Type", "text/html; charset=utf-8")
+	w.Header().Add("Refresh", fmt.Sprintf("1; url=%s", setting.AppSubURL+"/"))
+	// do not use 30x status, because the "post-install" page needs to use 404/200 to detect if Gitea has been installed.
+	// the fetch API could follow 30x requests to the page with 200 status.
+	w.WriteHeader(http.StatusNotFound)
+	_, _ = fmt.Fprintf(w, `Not Found. <a href="%s">Go to default page</a>.`, html.EscapeString(setting.AppSubURL+"/"))
 }