GoTftpd + Shoelaces = <3

go-tftpd.go

package main

import (
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"time"

	"github.com/pin/tftp"
)

var allowedFiles = [...]string{"undionly.kpxe"}

func checkAllowed(filename string) bool {
	for _, file := range allowedFiles {
		if file == filename {
			return true
		}
	}
	return false
}

func readHandler(filename string, rf io.ReaderFrom) error {
	if !checkAllowed(filename) {
		return errors.New("Not allowed")
	}
	raddr := rf.(tftp.OutgoingTransfer).RemoteAddr()
	log.Println("RRQ from", raddr.String())
	file, err := os.Open(filename)
	if err != nil {
		fmt.Fprintf(os.Stderr, "%v\n", err)
		return err
	}
	n, err := rf.ReadFrom(file)
	if err != nil {
		fmt.Fprintf(os.Stderr, "%v\n", err)
		return err
	}
	fmt.Printf("%d bytes sent\n", n)
	return nil
}

func main() {
	s := tftp.NewServer(readHandler, nil)
	s.SetTimeout(5 * time.Second)
	err := s.ListenAndServe("192.168.56.1:69")
	if err != nil {
		fmt.Fprintf(os.Stdout, "server: %v\n", err)
		os.Exit(1)
	}
}