Mirrors/smtpd
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Initial checkin.

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This commit is contained in:
Christian Joergensen 2014-07-13 23:24:13 +02:00
commit ac162dc7ac
5 changed files with 478 additions and 0 deletions
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46
cmd/smtpd/main.go Normal file
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package main
import (
"bitbucket.org/chrj/smtpd"
"crypto/tls"
"flag"
"log"
)
func dumpMessage(peer smtpd.Peer, env smtpd.Envelope) error {
log.Printf("New mail from: %s", env.MailFrom)
return nil
}
var tlsCert = flag.String("tlscert", "", "TLS: Certificate file")
var tlsKey = flag.String("tlskey", "", "TLS: Private key")
func main() {
flag.Parse()
var tlsConfig *tls.Config
if *tlsCert != "" {
cert, err := tls.LoadX509KeyPair(*tlsCert, *tlsKey)
if err != nil {
log.Fatal("certificate error:", err)
}
tlsConfig = &tls.Config{
Certificates: []tls.Certificate{cert},
}
}
server := &smtpd.Server{
Addr: "127.0.0.1:10025",
WelcomeMessage: "localhost ESMTP ready.",
Handler: dumpMessage,
TLSConfig: tlsConfig,
ForceTLS: true,
}
server.ListenAndServe()
return
}

20
cmd/smtpd/smtpd.crt Normal file
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-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

17
cmd/smtpd/smtpd.csr Normal file
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-----BEGIN CERTIFICATE REQUEST-----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-----END CERTIFICATE REQUEST-----

27
cmd/smtpd/smtpd.key Normal file
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-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

368
smtpd.go Normal file
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package smtpd
import (
"bufio"
"bytes"
"crypto/tls"
"fmt"
"log"
"net"
"strings"
"time"
)
type Server struct {
Addr string // Address to listen on
WelcomeMessage string // Initial server banner
ReadTimeout time.Duration // Socket timeout for read operations (default: 60s)
WriteTimeout time.Duration // Socket timeout for write operations (default: 60s)
// New e-mails are handed off to this function.
// If an error is returned, it will be reported in the SMTP session
Handler func(peer Peer, env Envelope) error
// Enable PLAIN/LOGIN authentication
Authenticator func(peer Peer, username, password string) error
TLSConfig *tls.Config // Enable STARTTLS support
ForceTLS bool // Force STARTTLS usage
MaxMessageSize int // Max message size in bytes (default: 10240000)
}
type sessionState int
const (
_STATE_HELO sessionState = iota
_STATE_AUTH
_STATE_MAIL
_STATE_RCPT
_STATE_DATA
)
type session struct {
server *Server
conn net.Conn
reader *bufio.Reader
writer *bufio.Writer
peer Peer
state sessionState
tls bool
}
type Peer struct {
HeloName string // Server name used in HELO/EHLO command
UserName string // Username from authentication
Addr net.Addr // Network address
}
type MailAddress string
type Envelope struct {
MailFrom MailAddress
Recipients []MailAddress
Data []byte
Peer *Peer
}
func (srv *Server) newConnection(c net.Conn) (s *session, err error) {
log.Printf("New connection from: %s", c.RemoteAddr())
s = &session{
server: srv,
conn: c,
reader: bufio.NewReader(c),
writer: bufio.NewWriter(c),
peer: Peer{Addr: c.RemoteAddr()},
}
return s, nil
}
func (srv *Server) ListenAndServe() error {
l, err := net.Listen("tcp", srv.Addr)
if err != nil {
return err
}
return srv.Serve(l)
}
func (srv *Server) Serve(l net.Listener) error {
srv.configureDefaults()
defer l.Close()
for {
conn, e := l.Accept()
if e != nil {
if ne, ok := e.(net.Error); ok && ne.Temporary() {
time.Sleep(time.Second)
continue
}
return e
}
session, err := srv.newConnection(conn)
if err != nil {
continue
}
session.state = _STATE_HELO
go session.serve()
}
}
func (srv *Server) configureDefaults() {
if srv.MaxMessageSize == 0 {
srv.MaxMessageSize = 10240000
}
if srv.ReadTimeout == 0 {
srv.ReadTimeout = time.Second * 60
}
if srv.WriteTimeout == 0 {
srv.WriteTimeout = time.Second * 60
}
if srv.ForceTLS && srv.TLSConfig == nil {
log.Fatal("Cannot use ForceTLS with no TLSConfig")
}
}
func (session *session) serve() {
log.Print("Serving")
defer func() {
session.writer.Flush()
session.conn.Close()
}()
session.reply(220, session.server.WelcomeMessage)
scanner := bufio.NewScanner(session.reader)
var env Envelope
var data *bytes.Buffer
for scanner.Scan() {
line := scanner.Text()
command := ""
fields := []string{}
params := []string{}
if session.state != _STATE_DATA {
fields = strings.Fields(line)
command = strings.ToUpper(fields[0])
if len(fields) > 1 {
params = strings.Split(fields[1], ":")
}
}
log.Printf("Line: %s, fields: %#v, params: %#v", line, fields, params)
if command == "QUIT" {
session.reply(250, "Ok, bye")
return
}
switch session.state {
case _STATE_HELO:
if command == "HELO" || command == "EHLO" {
if len(fields) < 2 {
session.reply(502, "Missing parameter")
continue
} else {
session.peer.HeloName = fields[1]
}
} else {
session.reply(502, "Command not recognized, expected HELO/EHLO")
continue
}
if command == "EHLO" {
session.WriteExtensions()
} else {
session.reply(250, "Go ahead")
}
if session.server.Authenticator == nil {
session.state = _STATE_MAIL
} else {
session.state = _STATE_AUTH
}
continue
case _STATE_MAIL:
if !session.tls && command == "STARTTLS" && session.server.TLSConfig != nil {
tls_conn := tls.Server(session.conn, session.server.TLSConfig)
session.reply(250, "Go ahead")
if err := tls_conn.Handshake(); err != nil {
log.Printf("TLS Handshake error:", err)
session.reply(550, "Handshake error")
continue
}
session.conn = tls_conn
session.reader = bufio.NewReader(tls_conn)
session.writer = bufio.NewWriter(tls_conn)
scanner = bufio.NewScanner(session.reader)
session.tls = true
session.state = _STATE_HELO
continue
}
if !session.tls && session.server.ForceTLS {
session.reply(550, "Must run STARTTLS first")
continue
}
if command == "MAIL" && strings.ToUpper(params[0]) == "FROM" {
addr, err := parseMailAddress(params[1])
if err != nil {
session.reply(502, "Ill-formatted e-mail address")
continue
}
env = Envelope{
Peer: &session.peer,
MailFrom: addr,
}
session.reply(250, "Go ahead")
session.state = _STATE_RCPT
continue
} else {
session.reply(502, "Command not recognized, expected MAIL FROM")
continue
}
case _STATE_RCPT:
if command == "RCPT" && strings.ToUpper(params[0]) == "TO" {
addr, err := parseMailAddress(params[1])
if err != nil {
session.reply(502, "Ill-formatted e-mail address")
continue
}
env.Recipients = append(env.Recipients, addr)
session.reply(250, "Go ahead")
continue
} else if command == "DATA" && len(env.Recipients) > 0 {
session.reply(250, "Go ahead. End your data with <CR><LF>.<CR><LF>")
data = &bytes.Buffer{}
session.state = _STATE_DATA
continue
}
if len(env.Recipients) == 0 {
session.reply(502, "Command not recognized, expected RCPT")
} else {
session.reply(502, "Command not recognized, expected RCPT or DATA")
}
continue
case _STATE_DATA:
if line == "." {
env.Data = data.Bytes()
data.Reset()
err := session.handle(env)
if err != nil {
session.reply(502, fmt.Sprintf("%s", err))
} else {
session.reply(200, "Thank you.")
}
session.state = _STATE_MAIL
continue
}
}
}
}
func (session *session) reply(code int, message string) {
fmt.Fprintf(session.writer, "%d %s\r\n", code, message)
session.conn.SetWriteDeadline(time.Now().Add(session.server.WriteTimeout))
session.writer.Flush()
session.conn.SetReadDeadline(time.Now().Add(session.server.ReadTimeout))
}
func (session *session) WriteExtensions() {
extensions := []string{
"SIZE 10240000",
}
if session.server.TLSConfig != nil && !session.tls {
extensions = append(extensions, "STARTTLS")
}
if session.tls {
extensions = append(extensions, "AUTH PLAIN LOGIN")
}
if len(extensions) > 1 {
for _, ext := range extensions[:len(extensions)-1] {
fmt.Fprintf(session.writer, "250-%s\r\n", ext)
}
}
session.reply(250, extensions[len(extensions)-1])
}
func (session *session) handle(env Envelope) error {
if session.server.Handler != nil {
return session.server.Handler(session.peer, env)
} else {
return nil
}
}
func parseMailAddress(src string) (MailAddress, error) {
if src[0] != '<' || src[len(src)-1] != '>' || strings.Count(src, "@") != 1 {
return MailAddress(""), fmt.Errorf("Ill-formatted e-mail address: %s", src)
}
return MailAddress(src[1 : len(src)-1]), nil
}