smtp.go

// Copyright (c) 2012-2013 Toby DiPasquale.
package main

import (
	"fmt"
	"github.com/codeslinger/log"
	"net"
)

// --- SMTP Service ---------------------------------------------------------

var DefaultIdent = "ESMTP Go25"

type SMTPService struct {
	cfg      Config
	addr     *net.TCPAddr
	exited   chan int
	draining bool
}

type Verdict int

const (
	Continue = iota
	Terminate
)

// Create a new SMTP server instance bound to the given TCP address.
func NewSMTPService(c Config, exited chan int) *SMTPService {
	return &SMTPService{
		cfg:      c,
		addr:     c.ListenLocal(),
		exited:   exited,
		draining: false,
	}
}

// Returns TCP address on which this server is listening.
func (s *SMTPService) Addr() *net.TCPAddr {
	return s.addr
}

// Shut down this SMTP server.
func (s *SMTPService) Shutdown() {
	s.draining = true
	s.exited <- 1
}

// Process an incoming SMTP connection.
func (s *SMTPService) Handle(conn *net.TCPConn) {
	defer func() {
		log.Trace(func() string {
			return fmt.Sprintf("%s: client disconnected", conn.RemoteAddr())
		})
		conn.Close()
	}()

	// Send a 421 error response if the server is in the process of shutting
	// down when the client connects.
	if s.draining {
		conn.Write(ResponseMap[421])
		return
	}
	session := NewSMTPSession(conn, s.cfg)
	if verdict := session.Greet(); verdict == Terminate {
		return
	}
	for {
		if verdict := session.Process(); verdict == Terminate {
			return
		}
	}
}

// Set TCP socket options on a new SMTP connection.
func (s *SMTPService) SetClientOptions(conn *net.TCPConn) error {
	if err := conn.SetKeepAlive(false); err != nil {
		log.Error("%s: SetKeepAlive: %v", conn.RemoteAddr(), err)
		return err
	}
	if err := conn.SetLinger(-1); err != nil {
		log.Error("%s: SetLinger: %v", conn.RemoteAddr(), err)
		return err
	}
	return nil
}