Fix several panics on invalid input
This commit is contained in:
Craig
commit
66f94a07ae
12 changed files with 2355 additions and 0 deletions
3
.hgignore
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3
.hgignore
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@ -0,0 +1,3 @@
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syntax: glob
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*.orig
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20
LICENSE
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20
LICENSE
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@ -0,0 +1,20 @@
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Copyright (c) 2014 Christian Joergensen (christian@technobabble.dk)
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MIT License
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Permission is hereby granted, free of charge, to any person obtaining a copy of
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this software and associated documentation files (the "Software"), to deal in
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the Software without restriction, including without limitation the rights to
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use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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the Software, and to permit persons to whom the Software is furnished to do so,
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subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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19
README.md
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19
README.md
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@ -0,0 +1,19 @@
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Go smtpd [](https://godoc.org/bitbucket.org/chrj/smtpd)
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========
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Package smtpd implements an SMTP server in golang.
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Features
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--------
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* STARTTLS (using `crypto/tls`)
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* Authentication (PLAIN/LOGIN, only after STARTTLS)
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* XCLIENT (for running behind a proxy)
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* Connection, HELO, sender and recipient checks for rejecting e-mails using callbacks
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* Configurable limits for: connection count, message size and recipient count
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* Hands incoming e-mail off to a configured callback function
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Feedback
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--------
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If you end up using this package or have any feedback, I'd very much like to hear about it. You can reach me by [email](mailto:christian@technobabble.dk).
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19
address.go
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19
address.go
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package smtpd
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import (
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"fmt"
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"strings"
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)
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func parseAddress(src string) (string, error) {
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if len(src) == 0 || src[0] != '<' || src[len(src)-1] != '>' {
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return "", fmt.Errorf("Ill-formatted e-mail address: %s", src)
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}
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if strings.Count(src, "@") > 1 {
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return "", fmt.Errorf("Ill-formatted e-mail address: %s", src)
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}
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return src[1 : len(src)-1], nil
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}
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54
envelope.go
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54
envelope.go
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package smtpd
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import (
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"crypto/tls"
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"fmt"
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"strings"
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"time"
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)
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// Envelope holds a message
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type Envelope struct {
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Sender string
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Recipients []string
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Data []byte
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}
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// AddReceivedLine prepends a Received header to the Data
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func (env *Envelope) AddReceivedLine(peer Peer) {
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tlsDetails := ""
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tlsVersions := map[uint16]string{
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tls.VersionSSL30: "SSL3.0",
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tls.VersionTLS10: "TLS1.0",
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tls.VersionTLS11: "TLS1.1",
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tls.VersionTLS12: "TLS1.2",
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}
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if peer.TLS != nil {
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tlsDetails = fmt.Sprintf(
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"\r\n\t(version=%s cipher=0x%x);",
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tlsVersions[peer.TLS.Version],
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peer.TLS.CipherSuite,
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)
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}
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line := wrap([]byte(fmt.Sprintf(
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"Received: from %s [%s] by %s with %s;%s\r\n\t%s\r\n",
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peer.HeloName,
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strings.Split(peer.Addr.String(), ":")[0],
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peer.ServerName,
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peer.Protocol,
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tlsDetails,
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time.Now().Format("Mon Jan 2 15:04:05 -0700 2006"),
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)))
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env.Data = append(env.Data, line...)
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// Move the new Received line up front
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copy(env.Data[len(line):], env.Data[0:len(env.Data)-len(line)])
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copy(env.Data, line)
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}
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46
example_test.go
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46
example_test.go
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package smtpd_test
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import (
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"bitbucket.org/chrj/smtpd"
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"errors"
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"net/smtp"
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"strings"
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)
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func ExampleServer() {
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var server *smtpd.Server
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// No-op server. Accepts and discards
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server = &smtpd.Server{}
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server.ListenAndServe("127.0.0.1:10025")
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// Relay server. Accepts only from single IP address and forwards using the Gmail smtp
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server = &smtpd.Server{
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HeloChecker: func(peer smtpd.Peer, name string) error {
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if !strings.HasPrefix(peer.Addr.String(), "42.42.42.42:") {
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return errors.New("Denied")
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}
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return nil
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},
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Handler: func(peer smtpd.Peer, env smtpd.Envelope) error {
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return smtp.SendMail(
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"smtp.gmail.com:587",
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smtp.PlainAuth(
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"",
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"username@gmail.com",
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"password",
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"smtp.gmail.com",
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),
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env.Sender,
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env.Recipients,
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env.Data,
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)
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},
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}
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server.ListenAndServe("127.0.0.1:10025")
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}
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80
examples/dkim-proxy/main.go
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80
examples/dkim-proxy/main.go
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// Command dkim-proxy implements a simple SMTP proxy that DKIM signs incoming e-mail and relays to another SMTP server for delivery
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package main
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import (
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"bytes"
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"flag"
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"io/ioutil"
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"log"
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"net/smtp"
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"bitbucket.org/chrj/smtpd"
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"github.com/eaigner/dkim"
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)
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var (
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welcomeMsg = flag.String("welcome", "DKIM-proxy ESMTP ready.", "Welcome message for SMTP session")
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inAddr = flag.String("inaddr", "localhost:10025", "Address to listen for incoming SMTP on")
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outAddr = flag.String("outaddr", "localhost:25", "Address to deliver outgoing SMTP on")
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privKeyFile = flag.String("key", "", "Private key file.")
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dkimS = flag.String("s", "default", "DKIM selector")
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dkimD = flag.String("d", "", "DKIM domain")
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dkimConf dkim.Conf
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privKey []byte
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)
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func handler(peer smtpd.Peer, env smtpd.Envelope) error {
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d, err := dkim.New(dkimConf, privKey)
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if err != nil {
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log.Printf("DKIM error: %v", err)
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return smtpd.Error{450, "Internal server error"}
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}
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// The dkim package expects \r\n newlines, so replace to that
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data, err := d.Sign(bytes.Replace(env.Data, []byte("\n"), []byte("\r\n"), -1))
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if err != nil {
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log.Printf("DKIM signing error: %v", err)
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return smtpd.Error{450, "Internal server error"}
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}
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return smtp.SendMail(
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*outAddr,
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nil,
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env.Sender,
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env.Recipients,
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data,
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)
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}
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func main() {
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flag.Parse()
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var err error
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dkimConf, err = dkim.NewConf(*dkimD, *dkimS)
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if err != nil {
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log.Fatalf("DKIM configuration error: %v", err)
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}
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privKey, err = ioutil.ReadFile(*privKeyFile)
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if err != nil {
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log.Fatalf("Couldn't read private key: %v", err)
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}
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_, err = dkim.New(dkimConf, privKey)
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if err != nil {
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log.Fatalf("DKIM error: %v", err)
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}
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server := &smtpd.Server{
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WelcomeMessage: *welcomeMsg,
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Handler: handler,
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}
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server.ListenAndServe(*inAddr)
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}
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582
protocol.go
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582
protocol.go
Normal file
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package smtpd
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import (
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"bufio"
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"bytes"
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"crypto/tls"
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"encoding/base64"
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"fmt"
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"io"
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"io/ioutil"
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"net"
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"net/textproto"
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"strconv"
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"strings"
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"time"
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)
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type command struct {
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line string
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action string
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fields []string
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params []string
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}
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func parseLine(line string) (cmd command) {
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cmd.line = line
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cmd.fields = strings.Fields(line)
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if len(cmd.fields) > 0 {
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cmd.action = strings.ToUpper(cmd.fields[0])
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if len(cmd.fields) > 1 {
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cmd.params = strings.Split(cmd.fields[1], ":")
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}
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}
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return
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}
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func (session *session) handle(line string) {
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cmd := parseLine(line)
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// Commands are dispatched to the appropriate handler functions.
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// If a network error occurs during handling, the handler should
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// just return and let the error be handled on the next read.
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switch cmd.action {
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case "HELO":
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session.handleHELO(cmd)
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return
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case "EHLO":
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session.handleEHLO(cmd)
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return
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case "MAIL":
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session.handleMAIL(cmd)
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return
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case "RCPT":
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session.handleRCPT(cmd)
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return
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case "STARTTLS":
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session.handleSTARTTLS(cmd)
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return
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case "DATA":
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session.handleDATA(cmd)
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return
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case "RSET":
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session.handleRSET(cmd)
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return
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case "NOOP":
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session.handleNOOP(cmd)
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return
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case "QUIT":
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session.handleQUIT(cmd)
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return
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case "AUTH":
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session.handleAUTH(cmd)
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return
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case "XCLIENT":
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session.handleXCLIENT(cmd)
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return
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}
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session.reply(502, "Unsupported command.")
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}
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func (session *session) handleHELO(cmd command) {
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if len(cmd.fields) < 2 {
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session.reply(502, "Missing parameter")
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return
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}
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if session.peer.HeloName != "" {
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// Reset envelope in case of duplicate HELO
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session.reset()
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}
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if session.server.HeloChecker != nil {
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err := session.server.HeloChecker(session.peer, cmd.fields[1])
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if err != nil {
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session.error(err)
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return
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}
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}
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session.peer.HeloName = cmd.fields[1]
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session.peer.Protocol = SMTP
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session.reply(250, "Go ahead")
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return
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}
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func (session *session) handleEHLO(cmd command) {
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if len(cmd.fields) < 2 {
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session.reply(502, "Missing parameter")
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return
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}
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if session.peer.HeloName != "" {
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// Reset envelope in case of duplicate EHLO
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session.reset()
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}
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if session.server.HeloChecker != nil {
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err := session.server.HeloChecker(session.peer, cmd.fields[1])
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if err != nil {
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session.error(err)
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return
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}
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}
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session.peer.HeloName = cmd.fields[1]
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session.peer.Protocol = ESMTP
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fmt.Fprintf(session.writer, "250-%s\r\n", session.server.Hostname)
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extensions := session.extensions()
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if len(extensions) > 1 {
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for _, ext := range extensions[:len(extensions)-1] {
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fmt.Fprintf(session.writer, "250-%s\r\n", ext)
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}
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}
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session.reply(250, extensions[len(extensions)-1])
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return
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}
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func (session *session) handleMAIL(cmd command) {
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if len(cmd.params) != 2 || strings.ToUpper(cmd.params[0]) != "FROM" {
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session.reply(502, "Syntax error")
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return
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}
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|
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if session.peer.HeloName == "" {
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session.reply(502, "Please introduce yourself first")
|
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return
|
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}
|
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|
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if !session.tls && session.server.ForceTLS {
|
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session.reply(502, "Please turn on TLS by issuing a STARTTLS command")
|
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return
|
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}
|
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|
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if session.envelope != nil {
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session.reply(502, "Duplicate MAIL")
|
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return
|
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}
|
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|
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addr, err := parseAddress(cmd.params[1])
|
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|
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if err != nil {
|
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session.reply(502, "Ill-formatted e-mail address")
|
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return
|
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}
|
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|
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if session.server.SenderChecker != nil {
|
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err = session.server.SenderChecker(session.peer, addr)
|
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if err != nil {
|
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session.error(err)
|
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return
|
||||
}
|
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}
|
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|
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session.envelope = &Envelope{
|
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Sender: addr,
|
||||
}
|
||||
|
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session.reply(250, "Go ahead")
|
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|
||||
return
|
||||
|
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}
|
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|
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func (session *session) handleRCPT(cmd command) {
|
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if len(cmd.params) != 2 || strings.ToUpper(cmd.params[0]) != "TO" {
|
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session.reply(502, "Syntax error")
|
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return
|
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}
|
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|
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if session.envelope == nil {
|
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session.reply(502, "Missing MAIL FROM command.")
|
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return
|
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}
|
||||
|
||||
if len(session.envelope.Recipients) >= session.server.MaxRecipients {
|
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session.reply(452, "Too many recipients")
|
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return
|
||||
}
|
||||
|
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addr, err := parseAddress(cmd.params[1])
|
||||
|
||||
if err != nil {
|
||||
session.reply(502, "Ill-formatted e-mail address")
|
||||
return
|
||||
}
|
||||
|
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if session.server.RecipientChecker != nil {
|
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err = session.server.RecipientChecker(session.peer, addr)
|
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if err != nil {
|
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session.error(err)
|
||||
return
|
||||
}
|
||||
}
|
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|
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session.envelope.Recipients = append(session.envelope.Recipients, addr)
|
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|
||||
session.reply(250, "Go ahead")
|
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|
||||
return
|
||||
|
||||
}
|
||||
|
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func (session *session) handleSTARTTLS(cmd command) {
|
||||
|
||||
if session.tls {
|
||||
session.reply(502, "Already running in TLS")
|
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return
|
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}
|
||||
|
||||
if session.server.TLSConfig == nil {
|
||||
session.reply(502, "TLS not supported")
|
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return
|
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}
|
||||
|
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tlsConn := tls.Server(session.conn, session.server.TLSConfig)
|
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session.reply(220, "Go ahead")
|
||||
|
||||
if err := tlsConn.Handshake(); err != nil {
|
||||
session.reply(550, "Handshake error")
|
||||
return
|
||||
}
|
||||
|
||||
// Reset envelope as a new EHLO/HELO is required after STARTTLS
|
||||
session.reset()
|
||||
|
||||
// Reset deadlines on the underlying connection before I replace it
|
||||
// with a TLS connection
|
||||
session.conn.SetDeadline(time.Time{})
|
||||
|
||||
// Replace connection with a TLS connection
|
||||
session.conn = tlsConn
|
||||
session.reader = bufio.NewReader(tlsConn)
|
||||
session.writer = bufio.NewWriter(tlsConn)
|
||||
session.scanner = bufio.NewScanner(session.reader)
|
||||
session.tls = true
|
||||
|
||||
// Save connection state on peer
|
||||
state := tlsConn.ConnectionState()
|
||||
session.peer.TLS = &state
|
||||
|
||||
// Flush the connection to set new timeout deadlines
|
||||
session.flush()
|
||||
|
||||
return
|
||||
|
||||
}
|
||||
|
||||
func (session *session) handleDATA(cmd command) {
|
||||
|
||||
if session.envelope == nil || len(session.envelope.Recipients) == 0 {
|
||||
session.reply(502, "Missing RCPT TO command.")
|
||||
return
|
||||
}
|
||||
|
||||
session.reply(354, "Go ahead. End your data with <CR><LF>.<CR><LF>")
|
||||
session.conn.SetDeadline(time.Now().Add(session.server.DataTimeout))
|
||||
|
||||
data := &bytes.Buffer{}
|
||||
reader := textproto.NewReader(session.reader).DotReader()
|
||||
|
||||
_, err := io.CopyN(data, reader, int64(session.server.MaxMessageSize))
|
||||
|
||||
if err == io.EOF {
|
||||
|
||||
// EOF was reached before MaxMessageSize
|
||||
// Accept and deliver message
|
||||
|
||||
session.envelope.Data = data.Bytes()
|
||||
|
||||
if err := session.deliver(); err != nil {
|
||||
session.error(err)
|
||||
} else {
|
||||
session.reply(250, "Thank you.")
|
||||
}
|
||||
|
||||
session.reset()
|
||||
|
||||
}
|
||||
|
||||
if err != nil {
|
||||
// Network error, ignore
|
||||
return
|
||||
}
|
||||
|
||||
// Discard the rest and report an error.
|
||||
_, err = io.Copy(ioutil.Discard, reader)
|
||||
|
||||
if err != nil {
|
||||
// Network error, ignore
|
||||
return
|
||||
}
|
||||
|
||||
session.reply(552, fmt.Sprintf(
|
||||
"Message exceeded max message size of %d bytes",
|
||||
session.server.MaxMessageSize,
|
||||
))
|
||||
|
||||
session.reset()
|
||||
|
||||
return
|
||||
|
||||
}
|
||||
|
||||
func (session *session) handleRSET(cmd command) {
|
||||
session.reset()
|
||||
session.reply(250, "Go ahead")
|
||||
return
|
||||
}
|
||||
|
||||
func (session *session) handleNOOP(cmd command) {
|
||||
session.reply(250, "Go ahead")
|
||||
return
|
||||
}
|
||||
|
||||
func (session *session) handleQUIT(cmd command) {
|
||||
session.reply(221, "OK, bye")
|
||||
session.close()
|
||||
return
|
||||
}
|
||||
|
||||
func (session *session) handleAUTH(cmd command) {
|
||||
if len(cmd.fields) < 2 {
|
||||
session.reply(502, "Invalid syntax.")
|
||||
return
|
||||
}
|
||||
|
||||
if session.server.Authenticator == nil {
|
||||
session.reply(502, "AUTH not supported.")
|
||||
return
|
||||
}
|
||||
|
||||
if session.peer.HeloName == "" {
|
||||
session.reply(502, "Please introduce yourself first.")
|
||||
return
|
||||
}
|
||||
|
||||
if !session.tls {
|
||||
session.reply(502, "Cannot AUTH in plain text mode. Use STARTTLS.")
|
||||
return
|
||||
}
|
||||
|
||||
mechanism := strings.ToUpper(cmd.fields[1])
|
||||
|
||||
username := ""
|
||||
password := ""
|
||||
|
||||
switch mechanism {
|
||||
|
||||
case "PLAIN":
|
||||
|
||||
auth := ""
|
||||
|
||||
if len(cmd.fields) < 3 {
|
||||
session.reply(334, "Give me your credentials")
|
||||
if !session.scanner.Scan() {
|
||||
return
|
||||
}
|
||||
auth = session.scanner.Text()
|
||||
} else {
|
||||
auth = cmd.fields[2]
|
||||
}
|
||||
|
||||
data, err := base64.StdEncoding.DecodeString(auth)
|
||||
|
||||
if err != nil {
|
||||
session.reply(502, "Couldn't decode your credentials")
|
||||
return
|
||||
}
|
||||
|
||||
parts := bytes.Split(data, []byte{0})
|
||||
|
||||
if len(parts) != 3 {
|
||||
session.reply(502, "Couldn't decode your credentials")
|
||||
return
|
||||
}
|
||||
|
||||
username = string(parts[1])
|
||||
password = string(parts[2])
|
||||
|
||||
case "LOGIN":
|
||||
|
||||
session.reply(334, "VXNlcm5hbWU6")
|
||||
|
||||
if !session.scanner.Scan() {
|
||||
return
|
||||
}
|
||||
|
||||
byteUsername, err := base64.StdEncoding.DecodeString(session.scanner.Text())
|
||||
|
||||
if err != nil {
|
||||
session.reply(502, "Couldn't decode your credentials")
|
||||
return
|
||||
}
|
||||
|
||||
session.reply(334, "UGFzc3dvcmQ6")
|
||||
|
||||
if !session.scanner.Scan() {
|
||||
return
|
||||
}
|
||||
|
||||
bytePassword, err := base64.StdEncoding.DecodeString(session.scanner.Text())
|
||||
|
||||
if err != nil {
|
||||
session.reply(502, "Couldn't decode your credentials")
|
||||
return
|
||||
}
|
||||
|
||||
username = string(byteUsername)
|
||||
password = string(bytePassword)
|
||||
|
||||
default:
|
||||
|
||||
session.reply(502, "Unknown authentication mechanism")
|
||||
return
|
||||
|
||||
}
|
||||
|
||||
err := session.server.Authenticator(session.peer, username, password)
|
||||
if err != nil {
|
||||
session.error(err)
|
||||
return
|
||||
}
|
||||
|
||||
session.peer.Username = username
|
||||
session.peer.Password = password
|
||||
|
||||
session.reply(235, "OK, you are now authenticated")
|
||||
|
||||
}
|
||||
|
||||
func (session *session) handleXCLIENT(cmd command) {
|
||||
if len(cmd.fields) < 2 {
|
||||
session.reply(502, "Invalid syntax.")
|
||||
return
|
||||
}
|
||||
|
||||
if !session.server.EnableXCLIENT {
|
||||
session.reply(550, "XCLIENT not enabled")
|
||||
return
|
||||
}
|
||||
|
||||
var (
|
||||
newHeloName = ""
|
||||
newAddr net.IP = nil
|
||||
newTCPPort uint64 = 0
|
||||
newUsername = ""
|
||||
newProto Protocol = ""
|
||||
)
|
||||
|
||||
for _, item := range cmd.fields[1:] {
|
||||
|
||||
parts := strings.Split(item, "=")
|
||||
|
||||
if len(parts) != 2 {
|
||||
session.reply(502, "Couldn't decode the command.")
|
||||
return
|
||||
}
|
||||
|
||||
name := parts[0]
|
||||
value := parts[1]
|
||||
|
||||
switch name {
|
||||
|
||||
case "NAME":
|
||||
// Unused in smtpd package
|
||||
continue
|
||||
|
||||
case "HELO":
|
||||
newHeloName = value
|
||||
continue
|
||||
|
||||
case "ADDR":
|
||||
newAddr = net.ParseIP(value)
|
||||
continue
|
||||
|
||||
case "PORT":
|
||||
var err error
|
||||
newTCPPort, err = strconv.ParseUint(value, 10, 16)
|
||||
if err != nil {
|
||||
session.reply(502, "Couldn't decode the command.")
|
||||
return
|
||||
}
|
||||
continue
|
||||
|
||||
case "LOGIN":
|
||||
newUsername = value
|
||||
continue
|
||||
|
||||
case "PROTO":
|
||||
if value == "SMTP" {
|
||||
newProto = SMTP
|
||||
} else if value == "ESMTP" {
|
||||
newProto = ESMTP
|
||||
}
|
||||
continue
|
||||
|
||||
default:
|
||||
session.reply(502, "Couldn't decode the command.")
|
||||
return
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
tcpAddr, ok := session.peer.Addr.(*net.TCPAddr)
|
||||
if !ok {
|
||||
session.reply(502, "Unsupported network connection")
|
||||
return
|
||||
}
|
||||
|
||||
if newHeloName != "" {
|
||||
session.peer.HeloName = newHeloName
|
||||
}
|
||||
|
||||
if newAddr != nil {
|
||||
tcpAddr.IP = newAddr
|
||||
}
|
||||
|
||||
if newTCPPort != 0 {
|
||||
tcpAddr.Port = int(newTCPPort)
|
||||
}
|
||||
|
||||
if newUsername != "" {
|
||||
session.peer.Username = newUsername
|
||||
}
|
||||
|
||||
if newProto != "" {
|
||||
session.peer.Protocol = newProto
|
||||
}
|
||||
|
||||
session.welcome()
|
||||
|
||||
}
|
||||
324
smtpd.go
Normal file
324
smtpd.go
Normal file
|
|
@ -0,0 +1,324 @@
|
|||
// Package smtpd implements an SMTP server with support for STARTTLS, authentication (PLAIN/LOGIN), XCLIENT and optional restrictions on the different stages of the SMTP session.
|
||||
package smtpd
|
||||
|
||||
import (
|
||||
"bufio"
|
||||
"crypto/tls"
|
||||
"fmt"
|
||||
"log"
|
||||
"net"
|
||||
"time"
|
||||
)
|
||||
|
||||
// Server defines the parameters for running the SMTP server
|
||||
type Server struct {
|
||||
Hostname string // Server hostname. (default: "localhost.localdomain")
|
||||
WelcomeMessage string // Initial server banner. (default: "<hostname> ESMTP ready.")
|
||||
|
||||
ReadTimeout time.Duration // Socket timeout for read operations. (default: 60s)
|
||||
WriteTimeout time.Duration // Socket timeout for write operations. (default: 60s)
|
||||
DataTimeout time.Duration // Socket timeout for DATA command (default: 5m)
|
||||
|
||||
MaxConnections int // Max concurrent connections, use -1 to disable. (default: 100)
|
||||
MaxMessageSize int // Max message size in bytes. (default: 10240000)
|
||||
MaxRecipients int // Max RCPT TO calls for each envelope. (default: 100)
|
||||
|
||||
// New e-mails are handed off to this function.
|
||||
// Can be left empty for a NOOP server.
|
||||
// If an error is returned, it will be reported in the SMTP session.
|
||||
Handler func(peer Peer, env Envelope) error
|
||||
|
||||
// Enable various checks during the SMTP session.
|
||||
// Can be left empty for no restrictions.
|
||||
// If an error is returned, it will be reported in the SMTP session.
|
||||
// Use the Error struct for access to error codes.
|
||||
ConnectionChecker func(peer Peer) error // Called upon new connection.
|
||||
HeloChecker func(peer Peer, name string) error // Called after HELO/EHLO.
|
||||
SenderChecker func(peer Peer, addr string) error // Called after MAIL FROM.
|
||||
RecipientChecker func(peer Peer, addr string) error // Called after each RCPT TO.
|
||||
|
||||
// Enable PLAIN/LOGIN authentication, only available after STARTTLS.
|
||||
// Can be left empty for no authentication support.
|
||||
Authenticator func(peer Peer, username, password string) error
|
||||
|
||||
EnableXCLIENT bool // Enable XCLIENT support (default: false)
|
||||
|
||||
TLSConfig *tls.Config // Enable STARTTLS support.
|
||||
ForceTLS bool // Force STARTTLS usage.
|
||||
}
|
||||
|
||||
// Protocol represents the protocol used in the SMTP session
|
||||
type Protocol string
|
||||
|
||||
const (
|
||||
SMTP Protocol = "SMTP"
|
||||
ESMTP = "ESMTP"
|
||||
)
|
||||
|
||||
// Peer represents the client connecting to the server
|
||||
type Peer struct {
|
||||
HeloName string // Server name used in HELO/EHLO command
|
||||
Username string // Username from authentication, if authenticated
|
||||
Password string // Password from authentication, if authenticated
|
||||
Protocol Protocol // Protocol used, SMTP or ESMTP
|
||||
ServerName string // A copy of Server.Hostname
|
||||
Addr net.Addr // Network address
|
||||
TLS *tls.ConnectionState // TLS Connection details, if on TLS
|
||||
}
|
||||
|
||||
// Error represents an Error reported in the SMTP session.
|
||||
type Error struct {
|
||||
Code int // The integer error code
|
||||
Message string // The error message
|
||||
}
|
||||
|
||||
// Error returns a string representation of the SMTP error
|
||||
func (e Error) Error() string { return fmt.Sprintf("%d %s", e.Code, e.Message) }
|
||||
|
||||
type session struct {
|
||||
server *Server
|
||||
|
||||
peer Peer
|
||||
envelope *Envelope
|
||||
|
||||
conn net.Conn
|
||||
|
||||
reader *bufio.Reader
|
||||
writer *bufio.Writer
|
||||
scanner *bufio.Scanner
|
||||
|
||||
tls bool
|
||||
}
|
||||
|
||||
func (srv *Server) newSession(c net.Conn) (s *session) {
|
||||
|
||||
s = &session{
|
||||
server: srv,
|
||||
conn: c,
|
||||
reader: bufio.NewReader(c),
|
||||
writer: bufio.NewWriter(c),
|
||||
peer: Peer{
|
||||
Addr: c.RemoteAddr(),
|
||||
ServerName: srv.Hostname,
|
||||
},
|
||||
}
|
||||
|
||||
s.scanner = bufio.NewScanner(s.reader)
|
||||
|
||||
return
|
||||
|
||||
}
|
||||
|
||||
// ListenAndServe starts the SMTP server and listens on the address provided
|
||||
func (srv *Server) ListenAndServe(addr string) error {
|
||||
|
||||
srv.configureDefaults()
|
||||
|
||||
l, err := net.Listen("tcp", addr)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
return srv.Serve(l)
|
||||
}
|
||||
|
||||
// Serve starts the SMTP server and listens on the Listener provided
|
||||
func (srv *Server) Serve(l net.Listener) error {
|
||||
|
||||
srv.configureDefaults()
|
||||
|
||||
defer l.Close()
|
||||
|
||||
var limiter chan struct{}
|
||||
|
||||
if srv.MaxConnections > 0 {
|
||||
limiter = make(chan struct{}, srv.MaxConnections)
|
||||
} else {
|
||||
limiter = nil
|
||||
}
|
||||
|
||||
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 := srv.newSession(conn)
|
||||
|
||||
if limiter != nil {
|
||||
go func() {
|
||||
select {
|
||||
case limiter <- struct{}{}:
|
||||
session.serve()
|
||||
<-limiter
|
||||
default:
|
||||
session.reject()
|
||||
}
|
||||
}()
|
||||
} else {
|
||||
go session.serve()
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
func (srv *Server) configureDefaults() {
|
||||
|
||||
if srv.MaxMessageSize == 0 {
|
||||
srv.MaxMessageSize = 10240000
|
||||
}
|
||||
|
||||
if srv.MaxConnections == 0 {
|
||||
srv.MaxConnections = 100
|
||||
}
|
||||
|
||||
if srv.MaxRecipients == 0 {
|
||||
srv.MaxRecipients = 100
|
||||
}
|
||||
|
||||
if srv.ReadTimeout == 0 {
|
||||
srv.ReadTimeout = time.Second * 60
|
||||
}
|
||||
|
||||
if srv.WriteTimeout == 0 {
|
||||
srv.WriteTimeout = time.Second * 60
|
||||
}
|
||||
|
||||
if srv.DataTimeout == 0 {
|
||||
srv.DataTimeout = time.Minute * 5
|
||||
}
|
||||
|
||||
if srv.ForceTLS && srv.TLSConfig == nil {
|
||||
log.Fatal("Cannot use ForceTLS with no TLSConfig")
|
||||
}
|
||||
|
||||
if srv.Hostname == "" {
|
||||
srv.Hostname = "localhost.localdomain"
|
||||
}
|
||||
|
||||
if srv.WelcomeMessage == "" {
|
||||
srv.WelcomeMessage = fmt.Sprintf("%s ESMTP ready.", srv.Hostname)
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
func (session *session) serve() {
|
||||
|
||||
defer session.close()
|
||||
|
||||
session.welcome()
|
||||
|
||||
for {
|
||||
|
||||
for session.scanner.Scan() {
|
||||
session.handle(session.scanner.Text())
|
||||
}
|
||||
|
||||
err := session.scanner.Err()
|
||||
|
||||
if err == bufio.ErrTooLong {
|
||||
|
||||
session.reply(500, "Line too long")
|
||||
|
||||
// Advance reader to the next newline
|
||||
|
||||
session.reader.ReadString('\n')
|
||||
session.scanner = bufio.NewScanner(session.reader)
|
||||
|
||||
// Reset and have the client start over.
|
||||
|
||||
session.reset()
|
||||
|
||||
continue
|
||||
}
|
||||
|
||||
break
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
func (session *session) reject() {
|
||||
session.reply(421, "Too busy. Try again later.")
|
||||
session.close()
|
||||
}
|
||||
|
||||
func (session *session) reset() {
|
||||
session.envelope = nil
|
||||
}
|
||||
|
||||
func (session *session) welcome() {
|
||||
|
||||
if session.server.ConnectionChecker != nil {
|
||||
err := session.server.ConnectionChecker(session.peer)
|
||||
if err != nil {
|
||||
session.error(err)
|
||||
session.close()
|
||||
return
|
||||
}
|
||||
}
|
||||
|
||||
session.reply(220, session.server.WelcomeMessage)
|
||||
|
||||
}
|
||||
|
||||
func (session *session) reply(code int, message string) {
|
||||
fmt.Fprintf(session.writer, "%d %s\r\n", code, message)
|
||||
session.flush()
|
||||
}
|
||||
|
||||
func (session *session) flush() {
|
||||
session.conn.SetWriteDeadline(time.Now().Add(session.server.WriteTimeout))
|
||||
session.writer.Flush()
|
||||
session.conn.SetReadDeadline(time.Now().Add(session.server.ReadTimeout))
|
||||
}
|
||||
|
||||
func (session *session) error(err error) {
|
||||
if smtpdError, ok := err.(Error); ok {
|
||||
session.reply(smtpdError.Code, smtpdError.Message)
|
||||
} else {
|
||||
session.reply(502, fmt.Sprintf("%s", err))
|
||||
}
|
||||
}
|
||||
|
||||
func (session *session) extensions() []string {
|
||||
|
||||
extensions := []string{
|
||||
fmt.Sprintf("SIZE %d", session.server.MaxMessageSize),
|
||||
"8BITMIME",
|
||||
"PIPELINING",
|
||||
}
|
||||
|
||||
if session.server.EnableXCLIENT {
|
||||
extensions = append(extensions, "XCLIENT")
|
||||
}
|
||||
|
||||
if session.server.TLSConfig != nil && !session.tls {
|
||||
extensions = append(extensions, "STARTTLS")
|
||||
}
|
||||
|
||||
if session.server.Authenticator != nil && session.tls {
|
||||
extensions = append(extensions, "AUTH PLAIN LOGIN")
|
||||
}
|
||||
|
||||
return extensions
|
||||
|
||||
}
|
||||
|
||||
func (session *session) deliver() error {
|
||||
if session.server.Handler != nil {
|
||||
return session.server.Handler(session.peer, *session.envelope)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (session *session) close() {
|
||||
session.writer.Flush()
|
||||
time.Sleep(200 * time.Millisecond)
|
||||
session.conn.Close()
|
||||
}
|
||||
1162
smtpd_test.go
Normal file
1162
smtpd_test.go
Normal file
File diff suppressed because it is too large
Load diff
22
wrap.go
Normal file
22
wrap.go
Normal file
|
|
@ -0,0 +1,22 @@
|
|||
package smtpd
|
||||
|
||||
// Wrap a byte slice paragraph for use in SMTP header
|
||||
func wrap(sl []byte) []byte {
|
||||
length := 0
|
||||
for i := 0; i < len(sl); i++ {
|
||||
if length > 76 && sl[i] == ' ' {
|
||||
sl = append(sl, 0, 0)
|
||||
copy(sl[i+2:], sl[i:])
|
||||
sl[i] = '\r'
|
||||
sl[i+1] = '\n'
|
||||
sl[i+2] = '\t'
|
||||
i += 2
|
||||
length = 0
|
||||
}
|
||||
if sl[i] == '\n' {
|
||||
length = 0
|
||||
}
|
||||
length++
|
||||
}
|
||||
return sl
|
||||
}
|
||||
24
wrap_test.go
Normal file
24
wrap_test.go
Normal file
|
|
@ -0,0 +1,24 @@
|
|||
package smtpd
|
||||
|
||||
import (
|
||||
"testing"
|
||||
)
|
||||
|
||||
func TestWrap(t *testing.T) {
|
||||
|
||||
cases := map[string]string{
|
||||
"foobar": "foobar",
|
||||
"foobar quux": "foobar quux",
|
||||
"foobar\r\n": "foobar\r\n",
|
||||
"foobar\r\nquux": "foobar\r\nquux",
|
||||
"foobar quux foobar quux foobar quux foobar quux foobar quux foobar quux foobar quux foobar quux": "foobar quux foobar quux foobar quux foobar quux foobar quux foobar quux foobar\r\n\tquux foobar quux",
|
||||
"foobar quux foobar quux foobar quux foobar quux foobar quux foobar\r\n\tquux foobar quux foobar quux": "foobar quux foobar quux foobar quux foobar quux foobar quux foobar\r\n\tquux foobar quux foobar quux",
|
||||
}
|
||||
|
||||
for k, v := range cases {
|
||||
if string(wrap([]byte(k))) != v {
|
||||
t.Fatal("Didn't wrap correctly.")
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
Loading…
Add table
Reference in a new issue