func RunTCP(t TCPService) {
l, err := net.ListenTCP("tcp", t.Addr())
if err != nil {
log.Error("failed to bind to local address %s", t.Addr())
t.Shutdown()
return
}
defer l.Close()
log.Info("listening for connections on %s", t.Addr())
for {
conn, err := l.AcceptTCP()
if err != nil {
log.Error("failed to accept connection: %v", err)
continue
}
if err := t.SetClientOptions(conn); err != nil {
conn.Close()
continue
}
log.Trace(func() string {
return fmt.Sprintf("%s: client connected to %s", conn.RemoteAddr(), t.Addr())
})
go t.Handle(conn)
}
}
// 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
}
// Respond to client, reporting session termination if there was an error
// writing to the socket.
func (s *SMTPSession) codeWithVerdict(code int) Verdict {
if err := s.respondCode(code); err != nil {
log.Error("%s: failed to send response: %v", s.remote, err)
return Terminate
}
return Continue
}
// Respond to client, reporting session termination if there was an error
// writing to the socket.
func (s *SMTPSession) respondWithVerdict(code int, message string) Verdict {
if err := s.respond(code, message); err != nil {
log.Error("%s: failed to send response: %v", s.remote, err)
return Terminate
}
return Continue
}
func (c *config) readConfig(path string) (err error) {
file, err := os.Open(path)
if err != nil {
return
}
rd := bufio.NewReader(file)
idx := 0
for {
line, err := rd.ReadString('\n')
if err != nil {
if err == io.EOF {
break
}
log.Error("I/O error reading from file: %s: %v", path, err)
return err
}
idx++
line = strings.Trim(line, "\r\n")
// skip comments and blank lines
if len(strings.Trim(line, " ")) == 0 || line[0] == '#' {
continue
}
if err = c.parseLine(line, idx); err != nil {
return err
}
}
return nil
}
func main() {
flag.Parse()
cfg, err := LoadConfig(*configPath)
if err != nil {
log.Error("failed to load config: %s", err)
return
}
log.Info("loaded config: %s", cfg)
runtime.GOMAXPROCS(cfg.Cores())
exitChan := trapSignals()
go RunTCP(NewSMTPService(cfg, exitChan))
<-exitChan
}
// Process a DATA command.
func (s *SMTPSession) handleData(data []byte) Verdict {
if s.message.To.Len() < 1 {
return s.respondWithVerdict(554, "no valid recipients given")
}
if err := s.respondCode(354); err != nil {
return Terminate
}
s.state = dataReceived
body, err := s.readBody()
if err != nil {
log.Error("failed to read body of message: %v", err)
return Terminate
}
s.message.Body = body
s.state = bodyReceived
return s.codeWithVerdict(250)
}