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 return conn.line[len(command):], ReplyOK
144 func (conn *connection) doEHLO() {
148 _, err := fmt.Sscanf(conn.line, "%s %s", &cmd, &conn.ehlo)
150 conn.reply(ReplyBadSyntax)
155 conn.writeReply(250, fmt.Sprintf("Hello %s [%s]", conn.ehlo, conn.remoteAddr))
157 conn.tp.PrintfLine("250-Hello %s [%s]", conn.ehlo, conn.remoteAddr)
158 if conn.server.TLSConfig() != nil && conn.tlsNc == nil {
159 conn.tp.PrintfLine("250-STARTTLS")
161 conn.tp.PrintfLine("250 SIZE %d", 40960000)
164 conn.log.Info("doEHLO()", zap.String("ehlo", conn.ehlo))
166 conn.state = stateInitial
169 func (conn *connection) doSTARTTLS() {
170 if conn.state != stateInitial {
171 conn.reply(ReplyBadSequence)
175 tlsConfig := conn.server.TLSConfig()
176 if !conn.esmtp || tlsConfig == nil {
177 conn.writeReply(500, "unrecognized command")
181 conn.log.Info("doSTARTTLS()")
182 conn.writeReply(220, "initiate TLS connection")
184 newConn := tls.Server(conn.nc, tlsConfig)
185 if err := newConn.Handshake(); err != nil {
190 conn.tp = textproto.NewConn(conn.tlsNc)
191 conn.state = stateInitial
193 conn.log.Info("HELO again")
195 conn.writeReply(220, fmt.Sprintf("%s ESMTPS [%s] (mailpopbox)",
196 conn.server.Name(), newConn.LocalAddr()))
199 func (conn *connection) doMAIL() {
200 if conn.state != stateInitial {
201 conn.reply(ReplyBadSequence)
205 mailFrom, reply := conn.parsePath("MAIL FROM:")
206 if reply != ReplyOK {
212 conn.mailFrom, err = mail.ParseAddress(mailFrom)
214 conn.reply(ReplyBadSyntax)
218 conn.log.Info("doMAIL()", zap.String("address", conn.mailFrom.Address))
220 conn.state = stateMail
224 func (conn *connection) doRCPT() {
225 if conn.state != stateMail && conn.state != stateRecipient {
226 conn.reply(ReplyBadSequence)
230 rcptTo, reply := conn.parsePath("RCPT TO:")
231 if reply != ReplyOK {
236 address, err := mail.ParseAddress(rcptTo)
238 conn.reply(ReplyBadSyntax)
241 if reply := conn.server.VerifyAddress(*address); reply != ReplyOK {
242 conn.log.Warn("invalid address",
243 zap.String("address", address.Address),
244 zap.Stringer("reply", reply))
249 conn.log.Info("doRCPT()", zap.String("address", address.Address))
251 conn.rcptTo = append(conn.rcptTo, *address)
253 conn.state = stateRecipient
257 func (conn *connection) doDATA() {
258 if conn.state != stateRecipient {
259 conn.reply(ReplyBadSequence)
263 conn.writeReply(354, "Start mail input; end with <CRLF>.<CRLF>")
264 conn.log.Info("doDATA()")
266 data, err := conn.tp.ReadDotBytes()
268 conn.log.Error("failed to ReadDotBytes()",
270 zap.String("bytes", fmt.Sprintf("%x", data)))
271 conn.writeReply(552, "transaction failed")
275 received := time.Now()
277 RemoteAddr: conn.remoteAddr,
279 MailFrom: *conn.mailFrom,
282 ID: conn.envelopeID(received),
285 conn.log.Info("received message",
286 zap.Int("bytes", len(data)),
287 zap.Time("date", received),
288 zap.String("id", env.ID))
290 trace := conn.getReceivedInfo(env)
292 env.Data = append(trace, data...)
294 if reply := conn.server.OnMessageDelivered(env); reply != nil {
295 conn.log.Warn("message was rejected", zap.String("id", env.ID))
300 conn.state = stateInitial
304 func (conn *connection) envelopeID(t time.Time) string {
306 rand.Read(idBytes[:])
307 return fmt.Sprintf("m.%d.%x", t.UnixNano(), idBytes)
310 func (conn *connection) getReceivedInfo(envelope Envelope) []byte {
311 rhost, _, err := net.SplitHostPort(conn.remoteAddr.String())
313 rhost = conn.remoteAddr.String()
316 rhosts, err := net.LookupAddr(rhost)
318 rhost = fmt.Sprintf("%s [%s]", rhosts[0], rhost)
321 base := fmt.Sprintf("Received: from %s (%s)\r\n ", conn.ehlo, rhost)
327 if conn.tlsNc != nil {
330 base += fmt.Sprintf("by %s (mailpopbox) with %s id %s\r\n ", conn.server.Name(), with, envelope.ID)
332 base += fmt.Sprintf("for <%s>\r\n ", envelope.RcptTo[0].Address)
334 transport := conn.getTransportString()
335 date := envelope.Received.Format(time.RFC1123Z) // Same as RFC 5322 ยง 3.3
336 base += fmt.Sprintf("(using %s);\r\n %s\r\n", transport, date)
341 func (conn *connection) getTransportString() string {
342 if conn.tlsNc == nil {
346 ciphers := map[uint16]string{
347 tls.TLS_RSA_WITH_RC4_128_SHA: "TLS_RSA_WITH_RC4_128_SHA",
348 tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA: "TLS_RSA_WITH_3DES_EDE_CBC_SHA",
349 tls.TLS_RSA_WITH_AES_128_CBC_SHA: "TLS_RSA_WITH_AES_128_CBC_SHA",
350 tls.TLS_RSA_WITH_AES_256_CBC_SHA: "TLS_RSA_WITH_AES_256_CBC_SHA",
351 tls.TLS_RSA_WITH_AES_128_GCM_SHA256: "TLS_RSA_WITH_AES_128_GCM_SHA256",
352 tls.TLS_RSA_WITH_AES_256_GCM_SHA384: "TLS_RSA_WITH_AES_256_GCM_SHA384",
353 tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA: "TLS_ECDHE_ECDSA_WITH_RC4_128_SHA",
354 tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA: "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA",
355 tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA: "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA",
356 tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA: "TLS_ECDHE_RSA_WITH_RC4_128_SHA",
357 tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA: "TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA",
358 tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA",
359 tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA: "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA",
360 tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256: "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
361 tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
362 tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384: "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384",
363 tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
365 versions := map[uint16]string{
366 tls.VersionSSL30: "SSLv3.0",
367 tls.VersionTLS10: "TLSv1.0",
368 tls.VersionTLS11: "TLSv1.1",
369 tls.VersionTLS12: "TLSv1.2",
372 state := conn.tlsNc.ConnectionState()
374 version := versions[state.Version]
375 cipher := ciphers[state.CipherSuite]
378 version = fmt.Sprintf("%x", state.Version)
381 cipher = fmt.Sprintf("%x", state.CipherSuite)
385 if state.ServerName != "" {
386 name = fmt.Sprintf(" name=%s", state.ServerName)
389 return fmt.Sprintf("%s cipher=%s%s", version, cipher, name)
392 func (conn *connection) doRSET() {
393 conn.log.Info("doRSET()")
394 conn.state = stateInitial
399 func (conn *connection) resetBuffers() {
401 conn.rcptTo = make([]mail.Address, 0)