This is a toy example of an URL Shortener using a DNS Server as the key-value store.
Inspired by A URL shortener with an interesting storage backend.
One can make use of the TXT DNS record to store information in the server. One kind of information that you can store is a URL. So, creating the buffer.short TXT record on my domain brunocalza.me with the content a full URL path like https://brunocalza.me/how-buffer-pool-works-an-implementation-in-go/, one can create an URL Shortener service that does a DNS TXT Lookup on buffer.short.brunocalza.me, gets the full URL and does a redirect.
Access short.brunocalza.me/buffer in the browser.
dig buffer.short.brunocalza.me TXT +short
package main
import (
"context"
"log"
"net"
"net/http"
"strings"
)
const defaultPort = ":8080"
const domainName = "short.brunocalza.me"
const httpRedirect = 302
func main() {
http.HandleFunc("/", handleRequest)
http.ListenAndServe(defaultPort, nil)
}
func handleRequest(w http.ResponseWriter, r *http.Request) {
shortName := strings.TrimPrefix(r.URL.Path, "/")
dnsName := shortName + "." + domainName
resolver := net.DefaultResolver
response, err := resolver.LookupTXT(context.TODO(), dnsName)
if err != nil || len(response) == 0 {
log.Print(err)
w.Write([]byte("Error in DNS lookup\n"))
return
}
http.Redirect(w, r, response[0], httpRedirect)
}