Yet Another DKIM Verifier

Why not?

I found some DKIM solution for go, but I don’t like untested C binding and I have some time (thank you mr.Putin) I wrote this code for my pet project.

What can we do?

We can verify DKIM headers very fast. It is about 44mb per second on my laptop. We support custom resolving and custom cache logic.

TODO

• Support Length tag
• Support Time
• Support ExpireTime
• Support Copied header fields (z=)
• Sign

How to use it?

package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"

	"github.com/kalloc/dkim"
)

// ./test path/to/emls/*.eml

func main() {
	var (
		filename string
		fp       *os.File
		err      error
		dk       *dkim.DKIM
	)

	flag.Parse()

	for _, filename = range flag.Args() {
		fmt.Printf("Check: %s — ", filename)
		if fp, err = os.Open(filename); err != nil {
			fmt.Printf("ERR-WRONG_FILE")
		} else if dk, _ = dkim.ParseEml(bufio.NewReader(fp)); dk == nil {
			fmt.Printf("ERR-DKIM_NOT_FOUND")
		} else if _, err = dk.GetPublicKey(); err != nil {
			fmt.Printf("ERR-DKIM_PK_NOT_FOUND")
		} else if dk.Verify() == false {
			fmt.Printf("ERR-DKIM_NOT_VERIFIED (Body is %v, Sig is %v)", dk.Status.ValidBody, dk.Status.Valid)
		} else {
			fmt.Printf("OK")
		}
		fmt.Printf("\n")
	}
}