smtp.go

   1 package main
   2
   3 import (
   4         "crypto/tls"
   5         "fmt"
   6         "net"
   7         "net/mail"
   8         "os"
   9         "path"
  10         "strings"
  11
  12         "github.com/uber-go/zap"
  13
  14         "src.bluestatic.org/mailpopbox/smtp"
  15 )
  16
  17 func runSMTPServer(config Config, log zap.Logger) <-chan ServerControlMessage {
  18         server := smtpServer{
  19                 config:      config,
  20                 controlChan: make(chan ServerControlMessage),
  21                 log:         log.With(zap.String("server", "smtp")),
  22         }
  23         go server.run()
  24         return server.controlChan
  25 }
  26
  27 type smtpServer struct {
  28         config    Config
  29         tlsConfig *tls.Config
  30
  31         log zap.Logger
  32
  33         controlChan chan ServerControlMessage
  34 }
  35
  36 func (server *smtpServer) run() {
  37         if !server.loadTLSConfig() {
  38                 return
  39         }
  40
  41         addr := fmt.Sprintf(":%d", server.config.SMTPPort)
  42         server.log.Info("starting server", zap.String("address", addr))
  43
  44         l, err := net.Listen("tcp", addr)
  45         if err != nil {
  46                 server.log.Error("listen", zap.Error(err))
  47                 server.controlChan <- ServerControlFatalError
  48                 return
  49         }
  50
  51         connChan := make(chan net.Conn)
  52         go RunAcceptLoop(l, connChan, server.log)
  53
  54         reloadChan := CreateReloadSignal()
  55
  56         for {
  57                 select {
  58                 case <-reloadChan:
  59                         if !server.loadTLSConfig() {
  60                                 return
  61                         }
  62                 case conn, ok := <-connChan:
  63                         if ok {
  64                                 go smtp.AcceptConnection(conn, server, server.log)
  65                         } else {
  66                                 break
  67                         }
  68                 }
  69         }
  70 }
  71
  72 func (server *smtpServer) loadTLSConfig() bool {
  73         var err error
  74         server.tlsConfig, err = server.config.GetTLSConfig()
  75         if err != nil {
  76                 server.log.Error("failed to configure TLS", zap.Error(err))
  77                 server.controlChan <- ServerControlFatalError
  78                 return false
  79         }
  80         server.log.Info("loaded TLS config")
  81         return true
  82 }
  83
  84 func (server *smtpServer) Name() string {
  85         return server.config.Hostname
  86 }
  87
  88 func (server *smtpServer) TLSConfig() *tls.Config {
  89         return server.tlsConfig
  90 }
  91
  92 func (server *smtpServer) VerifyAddress(addr mail.Address) smtp.ReplyLine {
  93         if server.maildropForAddress(addr) == "" {
  94                 return smtp.ReplyBadMailbox
  95         }
  96         return smtp.ReplyOK
  97 }
  98
  99 func (server *smtpServer) OnEHLO() *smtp.ReplyLine {
 100         return nil
 101 }
 102
 103 func (server *smtpServer) OnMessageDelivered(en smtp.Envelope) *smtp.ReplyLine {
 104         maildrop := server.maildropForAddress(en.RcptTo[0])
 105         if maildrop == "" {
 106                 // TODO: log error
 107                 return &smtp.ReplyBadMailbox
 108         }
 109
 110         f, err := os.Create(path.Join(maildrop, en.ID+".msg"))
 111         if err != nil {
 112                 // TODO: log error
 113                 return &smtp.ReplyBadMailbox
 114         }
 115
 116         smtp.WriteEnvelopeForDelivery(f, en)
 117         f.Close()
 118         return nil
 119 }
 120
 121 func (server *smtpServer) maildropForAddress(addr mail.Address) string {
 122         domainIdx := strings.LastIndex(addr.Address, "@")
 123         if domainIdx == -1 {
 124                 return ""
 125         }
 126
 127         domain := addr.Address[domainIdx+1:]
 128
 129         for _, s := range server.config.Servers {
 130                 if domain == s.Domain {
 131                         return s.MaildropPath
 132                 }
 133         }
 134
 135         return ""
 136 }