Multicast to HTTP in Go

mcproxy.go

package main

import (
    "log"
    "net"
    "net/http"
    "regexp"
    "io"
    "strconv"
)

func handle_request(w http.ResponseWriter, r *http.Request) {
    re := regexp.MustCompile(`^/(\d+\.\d+\.\d+\.\d+)/(\d+)(?:/.*)$`)
    m := re.FindStringSubmatch(r.URL.Path)
    if m == nil {
        log.Print("did not match")
        http.NotFound(w, r)
        return
    }

    addr := net.ParseIP(m[1])
    if addr == nil {
        log.Print("invalid IP address")
        http.NotFound(w, r)
        return
    }

    port, err := strconv.Atoi(m[2])
    if err != nil || port < 0 || port > 65535 {
        log.Print(err)
        http.NotFound(w, r)
        return
    }

    conn, err := net.ListenMulticastUDP("udp", nil, &net.UDPAddr{
        addr,
        port,
    })

    if err != nil {
        log.Printf("could not create UDP socket: %s", err)
        conn.Close()
        return
    }

    w.Header().Set("Content-Type", "application/octet-stream")
    io.Copy(w, conn)

    conn.Close()
}

func main() {
    http.HandleFunc("/", handle_request)
    log.Fatal(http.ListenAndServe(":8080", nil))
}