13 "github.com/uber-go/zap"
19 stateNew state = iota // Before EHLO.
26 type connection struct {
43 mailFrom *mail.Address
47 func AcceptConnection(netConn net.Conn, server Server, log zap.Logger) {
50 tp: textproto.NewConn(netConn),
52 remoteAddr: netConn.RemoteAddr(),
53 log: log.With(zap.Stringer("client", netConn.RemoteAddr())),
57 conn.writeReply(220, fmt.Sprintf("%s ESMTP [%s] (mailpopbox)", server.Name(), netConn.LocalAddr()))
61 conn.line, err = conn.tp.ReadLine()
63 conn.log.Error("ReadLine()", zap.Error(err))
68 conn.log.Info("ReadLine()", zap.String("line", conn.line))
71 if _, err = fmt.Sscanf(conn.line, "%s", &cmd); err != nil {
72 conn.reply(ReplyBadSyntax)
76 switch strings.ToUpper(cmd) {
78 conn.writeReply(221, "Goodbye")
98 conn.writeReply(252, "I'll do my best")
100 conn.writeReply(550, "access denied")
104 conn.writeReply(250, "https://tools.ietf.org/html/rfc5321")
106 conn.writeReply(500, "unrecognized command")
111 func (conn *connection) reply(reply ReplyLine) error {
112 return conn.writeReply(reply.Code, reply.Message)
115 func (conn *connection) writeReply(code int, msg string) error {
116 conn.log.Info("writeReply", zap.Int("code", code))
119 err = conn.tp.PrintfLine("%d %s", code, msg)
121 err = conn.tp.PrintfLine("%d", code)
124 conn.log.Error("writeReply",
125 zap.Int("code", code),
131 // parsePath parses out either a forward-, reverse-, or return-path from the
132 // current connection line. Returns a (valid-path, ReplyOK) if it was
133 // successfully parsed.
134 func (conn *connection) parsePath(command string) (string, ReplyLine) {
135 if len(conn.line) < len(command) {
136 return "", ReplyBadSyntax
138 if strings.ToUpper(command) != strings.ToUpper(conn.line[:len(command)]) {
139 return "", ReplyLine{500, "unrecognized command"}
141 params := conn.line[len(command):]
142 idx := strings.Index(params, ">")
144 return "", ReplyBadSyntax
146 return params[:idx+1], ReplyOK
149 func (conn *connection) doEHLO() {
153 _, err := fmt.Sscanf(conn.line, "%s %s", &cmd, &conn.ehlo)
155 conn.reply(ReplyBadSyntax)
160 conn.writeReply(250, fmt.Sprintf("Hello %s [%s]", conn.ehlo, conn.remoteAddr))
162 conn.tp.PrintfLine("250-Hello %s [%s]", conn.ehlo, conn.remoteAddr)
163 if conn.server.TLSConfig() != nil && conn.tlsNc == nil {
164 conn.tp.PrintfLine("250-STARTTLS")
166 conn.tp.PrintfLine("250 SIZE %d", 40960000)
169 conn.log.Info("doEHLO()", zap.String("ehlo", conn.ehlo))
171 conn.state = stateInitial
174 func (conn *connection) doSTARTTLS() {
175 if conn.state != stateInitial {
176 conn.reply(ReplyBadSequence)
180 tlsConfig := conn.server.TLSConfig()
181 if !conn.esmtp || tlsConfig == nil {
182 conn.writeReply(500, "unrecognized command")
186 conn.log.Info("doSTARTTLS()")
187 conn.writeReply(220, "initiate TLS connection")
189 newConn := tls.Server(conn.nc, tlsConfig)
190 if err := newConn.Handshake(); err != nil {
195 conn.tp = textproto.NewConn(conn.tlsNc)
196 conn.state = stateInitial
198 conn.log.Info("HELO again")
200 conn.writeReply(220, fmt.Sprintf("%s ESMTPS [%s] (mailpopbox)",
201 conn.server.Name(), newConn.LocalAddr()))
204 func (conn *connection) doMAIL() {
205 if conn.state != stateInitial {
206 conn.reply(ReplyBadSequence)
210 mailFrom, reply := conn.parsePath("MAIL FROM:")
211 if reply != ReplyOK {
217 conn.mailFrom, err = mail.ParseAddress(mailFrom)
218 if err != nil || conn.mailFrom == nil {
219 conn.reply(ReplyBadSyntax)
223 conn.log.Info("doMAIL()", zap.String("address", conn.mailFrom.Address))
225 conn.state = stateMail
229 func (conn *connection) doRCPT() {
230 if conn.state != stateMail && conn.state != stateRecipient {
231 conn.reply(ReplyBadSequence)
235 rcptTo, reply := conn.parsePath("RCPT TO:")
236 if reply != ReplyOK {
241 address, err := mail.ParseAddress(rcptTo)
243 conn.reply(ReplyBadSyntax)
247 if reply := conn.server.VerifyAddress(*address); reply != ReplyOK {
248 conn.log.Warn("invalid address",
249 zap.String("address", address.Address),
250 zap.Stringer("reply", reply))
255 conn.log.Info("doRCPT()", zap.String("address", address.Address))
257 conn.rcptTo = append(conn.rcptTo, *address)
259 conn.state = stateRecipient
263 func (conn *connection) doDATA() {
264 if conn.state != stateRecipient {
265 conn.reply(ReplyBadSequence)
269 conn.writeReply(354, "Start mail input; end with <CRLF>.<CRLF>")
270 conn.log.Info("doDATA()")
272 data, err := conn.tp.ReadDotBytes()
274 conn.log.Error("failed to ReadDotBytes()",
276 zap.String("bytes", fmt.Sprintf("%x", data)))
277 conn.writeReply(552, "transaction failed")
281 received := time.Now()
283 RemoteAddr: conn.remoteAddr,
285 MailFrom: *conn.mailFrom,
288 ID: conn.envelopeID(received),
291 conn.log.Info("received message",
292 zap.Int("bytes", len(data)),
293 zap.Time("date", received),
294 zap.String("id", env.ID))
296 trace := conn.getReceivedInfo(env)
298 env.Data = append(trace, data...)
300 if reply := conn.server.OnMessageDelivered(env); reply != nil {
301 conn.log.Warn("message was rejected", zap.String("id", env.ID))
306 conn.state = stateInitial
310 func (conn *connection) envelopeID(t time.Time) string {
312 rand.Read(idBytes[:])
313 return fmt.Sprintf("m.%d.%x", t.UnixNano(), idBytes)
316 func (conn *connection) getReceivedInfo(envelope Envelope) []byte {
317 rhost, _, err := net.SplitHostPort(conn.remoteAddr.String())
319 rhost = conn.remoteAddr.String()
322 rhosts, err := net.LookupAddr(rhost)
324 rhost = fmt.Sprintf("%s [%s]", rhosts[0], rhost)
327 base := fmt.Sprintf("Received: from %s (%s)\r\n ", conn.ehlo, rhost)
333 if conn.tlsNc != nil {
336 base += fmt.Sprintf("by %s (mailpopbox) with %s id %s\r\n ", conn.server.Name(), with, envelope.ID)
338 base += fmt.Sprintf("for <%s>\r\n ", envelope.RcptTo[0].Address)
340 transport := conn.getTransportString()
341 date := envelope.Received.Format(time.RFC1123Z) // Same as RFC 5322 ยง 3.3
342 base += fmt.Sprintf("(using %s);\r\n %s\r\n", transport, date)
347 func (conn *connection) getTransportString() string {
348 if conn.tlsNc == nil {
352 ciphers := map[uint16]string{
353 tls.TLS_RSA_WITH_RC4_128_SHA: "TLS_RSA_WITH_RC4_128_SHA",
354 tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA: "TLS_RSA_WITH_3DES_EDE_CBC_SHA",
355 tls.TLS_RSA_WITH_AES_128_CBC_SHA: "TLS_RSA_WITH_AES_128_CBC_SHA",
356 tls.TLS_RSA_WITH_AES_256_CBC_SHA: "TLS_RSA_WITH_AES_256_CBC_SHA",
357 tls.TLS_RSA_WITH_AES_128_GCM_SHA256: "TLS_RSA_WITH_AES_128_GCM_SHA256",
358 tls.TLS_RSA_WITH_AES_256_GCM_SHA384: "TLS_RSA_WITH_AES_256_GCM_SHA384",
359 tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA: "TLS_ECDHE_ECDSA_WITH_RC4_128_SHA",
360 tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA: "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA",
361 tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA: "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA",
362 tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA: "TLS_ECDHE_RSA_WITH_RC4_128_SHA",
363 tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA: "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA",
364 tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA",
365 tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA: "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA",
366 tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256: "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
367 tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
368 tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384: "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384",
369 tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
371 versions := map[uint16]string{
372 tls.VersionSSL30: "SSLv3.0",
373 tls.VersionTLS10: "TLSv1.0",
374 tls.VersionTLS11: "TLSv1.1",
375 tls.VersionTLS12: "TLSv1.2",
378 state := conn.tlsNc.ConnectionState()
380 version := versions[state.Version]
381 cipher := ciphers[state.CipherSuite]
384 version = fmt.Sprintf("%x", state.Version)
387 cipher = fmt.Sprintf("%x", state.CipherSuite)
391 if state.ServerName != "" {
392 name = fmt.Sprintf(" name=%s", state.ServerName)
395 return fmt.Sprintf("%s cipher=%s%s", version, cipher, name)
398 func (conn *connection) doRSET() {
399 conn.log.Info("doRSET()")
400 conn.state = stateInitial
405 func (conn *connection) resetBuffers() {
407 conn.rcptTo = make([]mail.Address, 0)