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net/smtp: add optional Hello method
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Add a Hello method that allows clients to set the server sent in the EHLO/HELO exchange; the default remains localhost.
Based on CL 5555045 by rsc.

Fixes #4219.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6946057
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@rickar @rsc
rickar authored and rsc committed Dec 17, 2012
1 parent 013fa63 commit 475dee9
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Showing 2 changed files with 248 additions and 9 deletions.
65 changes: 57 additions & 8 deletions src/pkg/net/smtp/smtp.go
View file
Expand Up @@ -13,6 +13,7 @@ package smtp
import (
"crypto/tls"
"encoding/base64"
"errors"
"io"
"net"
"net/textproto"
Expand All @@ -33,7 +34,10 @@ type Client struct {
// map of supported extensions
ext map[string]string
// supported auth mechanisms
auth []string
auth []string
localName string // the name to use in HELO/EHLO
didHello bool // whether we've said HELO/EHLO
helloError error // the error from the hello
}

// Dial returns a new Client connected to an SMTP server at addr.
Expand All @@ -55,12 +59,33 @@ func NewClient(conn net.Conn, host string) (*Client, error) {
text.Close()
return nil, err
}
c := &Client{Text: text, conn: conn, serverName: host}
err = c.ehlo()
if err != nil {
err = c.helo()
c := &Client{Text: text, conn: conn, serverName: host, localName: "localhost"}
return c, nil
}

// hello runs a hello exchange if needed.
func (c *Client) hello() error {
if !c.didHello {
c.didHello = true
err := c.ehlo()
if err != nil {
c.helloError = c.helo()
}
}
return c.helloError
}

// Hello sends a HELO or EHLO to the server as the given host name.
// Calling this method is only necessary if the client needs control
// over the host name used. The client will introduce itself as "localhost"
// automatically otherwise. If Hello is called, it must be called before
// any of the other methods.
func (c *Client) Hello(localName string) error {
if c.didHello {
return errors.New("smtp: Hello called after other methods")
}
return c, err
c.localName = localName
return c.hello()
}

// cmd is a convenience function that sends a command and returns the response
Expand All @@ -79,14 +104,14 @@ func (c *Client) cmd(expectCode int, format string, args ...interface{}) (int, s
// server does not support ehlo.
func (c *Client) helo() error {
c.ext = nil
_, _, err := c.cmd(250, "HELO localhost")
_, _, err := c.cmd(250, "HELO %s", c.localName)
return err
}

// ehlo sends the EHLO (extended hello) greeting to the server. It
// should be the preferred greeting for servers that support it.
func (c *Client) ehlo() error {
_, msg, err := c.cmd(250, "EHLO localhost")
_, msg, err := c.cmd(250, "EHLO %s", c.localName)
if err != nil {
return err
}
Expand All @@ -113,6 +138,9 @@ func (c *Client) ehlo() error {
// StartTLS sends the STARTTLS command and encrypts all further communication.
// Only servers that advertise the STARTTLS extension support this function.
func (c *Client) StartTLS(config *tls.Config) error {
if err := c.hello(); err != nil {
return err
}
_, _, err := c.cmd(220, "STARTTLS")
if err != nil {
return err
Expand All @@ -128,6 +156,9 @@ func (c *Client) StartTLS(config *tls.Config) error {
// does not necessarily indicate an invalid address. Many servers
// will not verify addresses for security reasons.
func (c *Client) Verify(addr string) error {
if err := c.hello(); err != nil {
return err
}
_, _, err := c.cmd(250, "VRFY %s", addr)
return err
}
Expand All @@ -136,6 +167,9 @@ func (c *Client) Verify(addr string) error {
// A failed authentication closes the connection.
// Only servers that advertise the AUTH extension support this function.
func (c *Client) Auth(a Auth) error {
if err := c.hello(); err != nil {
return err
}
encoding := base64.StdEncoding
mech, resp, err := a.Start(&ServerInfo{c.serverName, c.tls, c.auth})
if err != nil {
Expand Down Expand Up @@ -178,6 +212,9 @@ func (c *Client) Auth(a Auth) error {
// parameter.
// This initiates a mail transaction and is followed by one or more Rcpt calls.
func (c *Client) Mail(from string) error {
if err := c.hello(); err != nil {
return err
}
cmdStr := "MAIL FROM:<%s>"
if c.ext != nil {
if _, ok := c.ext["8BITMIME"]; ok {
Expand Down Expand Up @@ -227,6 +264,9 @@ func SendMail(addr string, a Auth, from string, to []string, msg []byte) error {
if err != nil {
return err
}
if err := c.hello(); err != nil {
return err
}
if ok, _ := c.Extension("STARTTLS"); ok {
if err = c.StartTLS(nil); err != nil {
return err
Expand Down Expand Up @@ -267,6 +307,9 @@ func SendMail(addr string, a Auth, from string, to []string, msg []byte) error {
// Extension also returns a string that contains any parameters the
// server specifies for the extension.
func (c *Client) Extension(ext string) (bool, string) {
if err := c.hello(); err != nil {
return false, ""
}
if c.ext == nil {
return false, ""
}
Expand All @@ -278,12 +321,18 @@ func (c *Client) Extension(ext string) (bool, string) {
// Reset sends the RSET command to the server, aborting the current mail
// transaction.
func (c *Client) Reset() error {
if err := c.hello(); err != nil {
return err
}
_, _, err := c.cmd(250, "RSET")
return err
}

// Quit sends the QUIT command and closes the connection to the server.
func (c *Client) Quit() error {
if err := c.hello(); err != nil {
return err
}
_, _, err := c.cmd(221, "QUIT")
if err != nil {
return err
Expand Down
192 changes: 191 additions & 1 deletion src/pkg/net/smtp/smtp_test.go
View file
Expand Up @@ -76,7 +76,7 @@ func TestBasic(t *testing.T) {
bcmdbuf := bufio.NewWriter(&cmdbuf)
var fake faker
fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(basicServer)), bcmdbuf)
c := &Client{Text: textproto.NewConn(fake)}
c := &Client{Text: textproto.NewConn(fake), localName: "localhost"}

if err := c.helo(); err != nil {
t.Fatalf("HELO failed: %s", err)
Expand All @@ -88,6 +88,7 @@ func TestBasic(t *testing.T) {
t.Fatalf("Second EHLO failed: %s", err)
}

c.didHello = true
if ok, args := c.Extension("aUtH"); !ok || args != "LOGIN PLAIN" {
t.Fatalf("Expected AUTH supported")
}
Expand Down Expand Up @@ -269,3 +270,192 @@ var newClient2Client = `EHLO localhost
HELO localhost
QUIT
`

func TestHello(t *testing.T) {

if len(helloServer) != len(helloClient) {
t.Fatalf("Hello server and client size mismatch")
}

for i := 0; i < len(helloServer); i++ {
server := strings.Join(strings.Split(baseHelloServer+helloServer[i], "\n"), "\r\n")
client := strings.Join(strings.Split(baseHelloClient+helloClient[i], "\n"), "\r\n")
var cmdbuf bytes.Buffer
bcmdbuf := bufio.NewWriter(&cmdbuf)
var fake faker
fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
c, err := NewClient(fake, "fake.host")
if err != nil {
t.Fatalf("NewClient: %v", err)
}
c.localName = "customhost"
err = nil

switch i {
case 0:
err = c.Hello("customhost")
case 1:
err = c.StartTLS(nil)
if err.Error() == "502 Not implemented" {
err = nil
}
case 2:
err = c.Verify("test@example.com")
case 3:
c.tls = true
c.serverName = "smtp.google.com"
err = c.Auth(PlainAuth("", "user", "pass", "smtp.google.com"))
case 4:
err = c.Mail("test@example.com")
case 5:
ok, _ := c.Extension("feature")
if ok {
t.Errorf("Expected FEATURE not to be supported")
}
case 6:
err = c.Reset()
case 7:
err = c.Quit()
case 8:
err = c.Verify("test@example.com")
if err != nil {
err = c.Hello("customhost")
if err != nil {
t.Errorf("Want error, got none")
}
}
default:
t.Fatalf("Unhandled command")
}

if err != nil {
t.Errorf("Command %d failed: %v", i, err)
}

bcmdbuf.Flush()
actualcmds := cmdbuf.String()
if client != actualcmds {
t.Errorf("Got:\n%s\nExpected:\n%s", actualcmds, client)
}
}
}

var baseHelloServer = `220 hello world
502 EH?
250-mx.google.com at your service
250 FEATURE
`

var helloServer = []string{
"",
"502 Not implemented\n",
"250 User is valid\n",
"235 Accepted\n",
"250 Sender ok\n",
"",
"250 Reset ok\n",
"221 Goodbye\n",
"250 Sender ok\n",
}

var baseHelloClient = `EHLO customhost
HELO customhost
`

var helloClient = []string{
"",
"STARTTLS\n",
"VRFY test@example.com\n",
"AUTH PLAIN AHVzZXIAcGFzcw==\n",
"MAIL FROM:<test@example.com>\n",
"",
"RSET\n",
"QUIT\n",
"VRFY test@example.com\n",
}

func TestSendMail(t *testing.T) {
server := strings.Join(strings.Split(sendMailServer, "\n"), "\r\n")
client := strings.Join(strings.Split(sendMailClient, "\n"), "\r\n")
var cmdbuf bytes.Buffer
bcmdbuf := bufio.NewWriter(&cmdbuf)
l, err := net.Listen("tcp", "127.0.0.1:0")
if err != nil {
t.Fatalf("Unable to to create listener: %v", err)
}
defer l.Close()

go func(l net.Listener, data []string, w *bufio.Writer) {
i := 0
conn, err := l.Accept()
if err != nil {
t.Log("Accept error: %v", err)
return
}
defer conn.Close()

tc := textproto.NewConn(conn)
for i < len(data) && data[i] != "" {
tc.PrintfLine(data[i])
for len(data[i]) >= 4 && data[i][3] == '-' {
i++
tc.PrintfLine(data[i])
}
read := false
for !read || data[i] == "354 Go ahead" {
msg, err := tc.ReadLine()
w.Write([]byte(msg + "\r\n"))
read = true
if err != nil {
t.Log("Read error: %v", err)
return
}
if data[i] == "354 Go ahead" && msg == "." {
break
}
}
i++
}
}(l, strings.Split(server, "\r\n"), bcmdbuf)

err = SendMail(l.Addr().String(), nil, "test@example.com", []string{"other@example.com"}, []byte(strings.Replace(`From: test@example.com
To: other@example.com
Subject: SendMail test
SendMail is working for me.
`, "\n", "\r\n", -1)))

if err != nil {
t.Errorf("%v", err)
}

bcmdbuf.Flush()
actualcmds := cmdbuf.String()
if client != actualcmds {
t.Errorf("Got:\n%s\nExpected:\n%s", actualcmds, client)
}
}

var sendMailServer = `220 hello world
502 EH?
250 mx.google.com at your service
250 Sender ok
250 Receiver ok
354 Go ahead
250 Data ok
221 Goodbye
`

var sendMailClient = `EHLO localhost
HELO localhost
MAIL FROM:<test@example.com>
RCPT TO:<other@example.com>
DATA
From: test@example.com
To: other@example.com
Subject: SendMail test
SendMail is working for me.
.
QUIT
`

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