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package main
import (
"embed"
"fmt"
"io/fs"
"log"
"net/http"
"strings"
)
const (
COOKIE_NAME_TOKEN = `token`
)
//go:embed build/frontend/public
var frontendEmbed embed.FS
func init() {
// /api/registration must always be accessible without authentication
router.HandleFunc("/api/registration", registration).Methods("POST")
protected := router.PathPrefix("/api").Subrouter()
protected.Use(authentication)
protected.HandleFunc("/version", version)
// frontend must come last to make sure /api takes precedence
frontend, err := fs.Sub(frontendEmbed, "build/frontend/public")
if err != nil {
log.Fatalf("No embedded frontend: %v.", err)
}
router.PathPrefix("/").Handler(http.FileServerFS(frontend))
}
func version(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, versionTxt)
}
func registration(w http.ResponseWriter, r *http.Request) {
token, err := NewToken()
if err != nil {
http.Error(w, "Failed to generate token.", http.StatusInternalServerError)
return
}
cookie := http.Cookie{
Name: COOKIE_NAME_TOKEN,
Value: token.Private(),
HttpOnly: true,
Secure: true,
SameSite: http.SameSiteStrictMode,
}
http.SetCookie(w, &cookie)
fmt.Fprintf(w, "%s\n", token.Public())
}
func authentication(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
cookie, err := r.Cookie(COOKIE_NAME_TOKEN)
if err != nil {
http.Error(w, "No authentication cookie present.", http.StatusForbidden)
return
}
candidate, found := strings.CutPrefix(cookie.String(), COOKIE_NAME_TOKEN + "=")
if !found {
http.Error(w, "Unexpected cookie prefix.", http.StatusForbidden)
return
}
user := authenticate(candidate)
if user == nil {
http.Error(w, "Unknown authentication token.", http.StatusForbidden)
return
}
log.Printf("Authenticated user number %d\n", *user)
next.ServeHTTP(w, r)
})
}
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