feat: initial commit

go.mod

@@ -0,0 +1,3 @@
+module github.com/jimeh/dotkatapult
+
+go 1.18

main.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+)
+
+func main() {
+	srv := &http.Server{
+		ReadTimeout:  5 * time.Second,
+		WriteTimeout: 5 * time.Second,
+		IdleTimeout:  30 * time.Second,
+		Handler:      http.HandlerFunc(handler),
+	}
+
+	port := "8080"
+	if v := os.Getenv("PORT"); v != "" {
+		port = v
+	}
+
+	ln, err := net.Listen("tcp", ":"+port)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Fatal(srv.Serve(ln))
+}
+
+func handler(w http.ResponseWriter, req *http.Request) {
+	target := "katapult.io"
+	hostname := strings.SplitN(req.Host, ":", 2)[0]
+
+	if strings.HasSuffix(hostname, ".katapult") {
+		sub := strings.TrimSuffix(hostname, ".katapult")
+		switch sub {
+		case "my":
+			target = "my.katapult.io"
+		case "io":
+			target = "katapult.io"
+		default:
+			target = "my.katapult.io/o/" + sub
+		}
+	}
+
+	w.Header().Set("Connection", "close")
+	url := fmt.Sprintf("https://%s", target)
+	http.Redirect(w, req, url, http.StatusTemporaryRedirect)
+}