milter-experiment/main.go

package main

import (
	"bufio"
	"bytes"
	"encoding/binary"
	"encoding/hex"
	"milter-experiment/logging"
	"os"
)

var (
	// Global logger for application wide logging. Not sure if this is a good pattern yet.
	logger logging.Logger
)

func handleMtaConnection(clientConnection *bufio.ReadWriter) {
	buf := make([]byte, 4096)
	for {
		bytesRead, err := clientConnection.Read(buf)
		if err != nil {
			logger.Errorln("Error reading from clientConnection:", err.Error())
			break
		} else {
			logger.Infof("Read %d bytes from connection\n", bytesRead)
			logger.Debugf("Hexdump of bytes read:\n%s", hex.Dump(buf[0:bytesRead]))

			// First 4 Bytes will be some integer thing "length"
			// Let's parse that
			var packetLength uint32
			bytesReader := bytes.NewReader(buf[0:4])
			err := binary.Read(bytesReader, binary.BigEndian, &packetLength)
			if err != nil {
				logger.Errorln(err.Error())
			}
			logger.Debugf("Parsed length: %d\n", packetLength)

			// Next up is a character, indicating the milter command
			logger.Debugf("Parsing command from byte: %X\n", buf[4])
			command := string(buf[4])
			logger.Debugf("Parsed packet command: %s\n", command)

			// Last part is data with lenght len-1
			data := make([]byte, packetLength)
			data = buf[5 : 5+packetLength-1]
			logger.Debugf("Hexdump of packet payload read:\n%s", hex.Dump(data))

		}
	}
}

func main() {
	logger = logging.NewLogger(os.Stdout, os.Stderr, logging.DEBUG)
	err := runServer("127.0.0.1:7777")
	if err != nil {
		logger.Errorf("Could not run server: %s\n", err.Error())
		os.Exit(1)
	}
}