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smtp: new package

Browse Source 
R=rsc, iant, agl
CC=golang-dev
https://golang.org/cl/2052042
This commit is contained in:
Evan Shaw 2010-10-13 22:07:28 -04:00 committed by Russ Cox
parent 52e3c99cfb
commit df74d8df09
5 changed files with 559 additions and 0 deletions
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1
src/pkg/Makefile
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@ -109,6 +109,7 @@ DIRS=\
runtime\ runtime\
runtime/pprof\ runtime/pprof\
scanner\ scanner\
smtp\
sort\ sort\
strconv\ strconv\
strings\ strings\

12
src/pkg/smtp/Makefile Normal file
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@ -0,0 +1,12 @@
# Copyright 2010 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.
include ../../Make.inc
TARG=smtp
GOFILES=\
auth.go\
smtp.go\
include ../../Make.pkg

69
src/pkg/smtp/auth.go Normal file
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@ -0,0 +1,69 @@
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package smtp
import (
"os"
)
// Auth is implemented by an SMTP authentication mechanism.
type Auth interface {
// Start begins an authentication with a server.
// It returns the name of the authentication protocol
// and optionally data to include in the initial AUTH message
// sent to the server. It can return proto == "" to indicate
// that the authentication should be skipped.
// If it returns a non-nil os.Error, the SMTP client aborts
// the authentication attempt and closes the connection.
Start(server *ServerInfo) (proto string, toServer []byte, err os.Error)
// Next continues the authentication. The server has just sent
// the fromServer data. If more is true, the server expects a
// response, which Next should return as toServer; otherwise
// Next should return toServer == nil.
// If Next returns a non-nil os.Error, the SMTP client aborts
// the authentication attempt and closes the connection.
Next(fromServer []byte, more bool) (toServer []byte, err os.Error)
}
// ServerInfo records information about an SMTP server.
type ServerInfo struct {
Name string // SMTP server name
TLS bool // using TLS, with valid certificate for Name
Auth []string // advertised authentication mechanisms
}
type plainAuth struct {
identity, username, password string
host string
}
// PlainAuth returns an Auth that implements the PLAIN authentication
// mechanism as defined in RFC 4616.
// The returned Auth uses the given username and password to authenticate
// on TLS connections to host and act as identity. Usually identity will be
// left blank to act as username.
func PlainAuth(identity, username, password, host string) Auth {
return &plainAuth{identity, username, password, host}
}
func (a *plainAuth) Start(server *ServerInfo) (string, []byte, os.Error) {
if !server.TLS {
return "", nil, os.NewError("unencrypted connection")
}
if server.Name != a.host {
return "", nil, os.NewError("wrong host name")
}
resp := []byte(a.identity + "\x00" + a.username + "\x00" + a.password)
return "PLAIN", resp, nil
}
func (a *plainAuth) Next(fromServer []byte, more bool) ([]byte, os.Error) {
if more {
// We've already sent everything.
return nil, os.NewError("unexpected server challenge")
}
return nil, nil
}

295
src/pkg/smtp/smtp.go Normal file
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@ -0,0 +1,295 @@
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package smtp implements the Simple Mail Transfer Protocol as defined in RFC 5321.
// It also implements the following extensions:
// 8BITMIME RFC 1652
// AUTH RFC 2554
// STARTTLS RFC 3207
// Additional extensions may be handled by clients.
package smtp
import (
"crypto/tls"
"encoding/base64"
"io"
"os"
"net"
"net/textproto"
"strings"
)
// A Client represents a client connection to an SMTP server.
type Client struct {
// Text is the textproto.Conn used by the Client. It is exported to allow for
// clients to add extensions.
Text *textproto.Conn
// keep a reference to the connection so it can be used to create a TLS
// connection later
conn net.Conn
// whether the Client is using TLS
tls bool
serverName string
// map of supported extensions
ext map[string]string
// supported auth mechanisms
auth []string
}
// Dial returns a new Client connected to an SMTP server at addr.
func Dial(addr string) (*Client, os.Error) {
conn, err := net.Dial("tcp", "", addr)
if err != nil {
return nil, err
}
host := addr[:strings.Index(addr, ":")]
return NewClient(conn, host)
}
// NewClient returns a new Client using an existing connection and host as a
// server name to be used when authenticating.
func NewClient(conn net.Conn, host string) (*Client, os.Error) {
text := textproto.NewConn(conn)
_, msg, err := text.ReadResponse(220)
if err != nil {
text.Close()
return nil, err
}
c := &Client{Text: text, conn: conn, serverName: host}
if strings.Index(msg, "ESMTP") >= 0 {
err = c.ehlo()
} else {
err = c.helo()
}
return c, err
}
// cmd is a convenience function that sends a command and returns the response
func (c *Client) cmd(expectCode int, format string, args ...interface{}) (int, string, os.Error) {
id, err := c.Text.Cmd(format, args...)
if err != nil {
return 0, "", err
}
c.Text.StartResponse(id)
defer c.Text.EndResponse(id)
code, msg, err := c.Text.ReadResponse(expectCode)
return code, msg, err
}
// helo sends the HELO greeting to the server. It should be used only when the
// server does not support ehlo.
func (c *Client) helo() os.Error {
c.ext = nil
_, _, err := c.cmd(250, "HELO localhost")
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() os.Error {
_, msg, err := c.cmd(250, "EHLO localhost")
if err != nil {
return err
}
ext := make(map[string]string)
extList := strings.Split(msg, "\n", -1)
if len(extList) > 1 {
extList = extList[1:]
for _, line := range extList {
args := strings.Split(line, " ", 2)
if len(args) > 1 {
ext[args[0]] = args[1]
} else {
ext[args[0]] = ""
}
}
}
if mechs, ok := ext["AUTH"]; ok {
c.auth = strings.Split(mechs, " ", -1)
}
c.ext = ext
return err
}
// StartTLS sends the STARTTLS command and encrypts all further communication.
// Only servers that advertise the STARTTLS extension support this function.
func (c *Client) StartTLS() os.Error {
_, _, err := c.cmd(220, "STARTTLS")
if err != nil {
return err
}
c.conn = tls.Client(c.conn, nil)
c.Text = textproto.NewConn(c.conn)
c.tls = true
return c.ehlo()
}
// Verify checks the validity of an email address on the server.
// If Verify returns nil, the address is valid. A non-nil return
// does not necessarily indicate an invalid address. Many servers
// will not verify addresses for security reasons.
func (c *Client) Verify(addr string) os.Error {
_, _, err := c.cmd(250, "VRFY %s", addr)
return err
}
// Auth authenticates a client using the provided authentication mechanism.
// A failed authentication closes the connection.
// Only servers that advertise the AUTH extension support this function.
func (c *Client) Auth(a Auth) os.Error {
encoding := base64.StdEncoding
mech, resp, err := a.Start(&ServerInfo{c.serverName, c.tls, c.auth})
if err != nil {
c.Quit()
return err
}
resp64 := make([]byte, encoding.EncodedLen(len(resp)))
encoding.Encode(resp64, resp)
code, msg64, err := c.cmd(0, "AUTH %s %s", mech, resp64)
for err == nil {
var msg []byte
switch code {
case 334:
msg = make([]byte, encoding.DecodedLen(len(msg64)))
_, err = encoding.Decode(msg, []byte(msg64))
case 235:
// the last message isn't base64 because it isn't a challenge
msg = []byte(msg64)
default:
err = &textproto.Error{code, msg64}
}
resp, err = a.Next(msg, code == 334)
if err != nil {
// abort the AUTH
c.cmd(501, "*")
c.Quit()
break
}
if resp == nil {
break
}
resp64 = make([]byte, encoding.EncodedLen(len(resp)))
encoding.Encode(resp64, resp)
code, msg64, err = c.cmd(0, string(resp64))
}
return err
}
// Mail issues a MAIL command to the server using the provided email address.
// If the server supports the 8BITMIME extension, Mail adds the BODY=8BITMIME
// parameter.
// This initiates a mail transaction and is followed by one or more Rcpt calls.
func (c *Client) Mail(from string) os.Error {
cmdStr := "MAIL FROM:<%s>"
if c.ext != nil {
if _, ok := c.ext["8BITMIME"]; ok {
cmdStr += " BODY=8BITMIME"
}
}
_, _, err := c.cmd(250, cmdStr, from)
return err
}
// Rcpt issues a RCPT command to the server using the provided email address.
// A call to Rcpt must be preceded by a call to Mail and may be followed by
// a Data call or another Rcpt call.
func (c *Client) Rcpt(to string) os.Error {
_, _, err := c.cmd(25, "RCPT TO:<%s>", to)
return err
}
type dataCloser struct {
c *Client
io.WriteCloser
}
func (d *dataCloser) Close() os.Error {
d.WriteCloser.Close()
_, _, err := d.c.Text.ReadResponse(250)
return err
}
// Data issues a DATA command to the server and returns a writer that
// can be used to write the data. The caller should close the writer
// before calling any more methods on c.
// A call to Data must be preceded by one or more calls to Rcpt.
func (c *Client) Data() (io.WriteCloser, os.Error) {
_, _, err := c.cmd(354, "DATA")
if err != nil {
return nil, err
}
return &dataCloser{c, c.Text.DotWriter()}, nil
}
// SendMail connects to the server at addr, switches to TLS if possible,
// authenticates with mechanism a if possible, and then sends an email from
// address from, to addresses to, with message msg.
func SendMail(addr string, a Auth, from string, to []string, msg []byte) os.Error {
c, err := Dial(addr)
if err != nil {
return err
}
if ok, _ := c.Extension("STARTTLS"); ok {
if err = c.StartTLS(); err != nil {
return err
}
}
if a != nil && c.ext != nil {
if _, ok := c.ext["AUTH"]; ok {
if err = c.Auth(a); err != nil {
return err
}
}
}
if err = c.Mail(from); err != nil {
return err
}
for _, addr := range to {
if err = c.Rcpt(addr); err != nil {
return err
}
}
w, err := c.Data()
if err != nil {
return err
}
_, err = w.Write(msg)
if err != nil {
return err
}
err = w.Close()
if err != nil {
return err
}
return c.Quit()
}
// Extension reports whether an extension is support by the server.
// The extension name is case-insensitive. If the extension is supported,
// Extension also returns a string that contains any parameters the
// server specifies for the extension.
func (c *Client) Extension(ext string) (bool, string) {
if c.ext == nil {
return false, ""
}
ext = strings.ToUpper(ext)
param, ok := c.ext[ext]
return ok, param
}
// Reset sends the RSET command to the server, aborting the current mail
// transaction.
func (c *Client) Reset() os.Error {
_, _, err := c.cmd(250, "RSET")
return err
}
// Quit sends the QUIT command and closes the connection to the server.
func (c *Client) Quit() os.Error {
_, _, err := c.cmd(221, "QUIT")
if err != nil {
return err
}
return c.Text.Close()
}

182
src/pkg/smtp/smtp_test.go Normal file
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@ -0,0 +1,182 @@
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package smtp
import (
"bufio"
"bytes"
"io"
"net/textproto"
"os"
"strings"
"testing"
)
type authTest struct {
auth Auth
challenges []string
name string
responses []string
}
var authTests = []authTest{
authTest{PlainAuth("", "user", "pass", "testserver"), []string{}, "PLAIN", []string{"\x00user\x00pass"}},
authTest{PlainAuth("foo", "bar", "baz", "testserver"), []string{}, "PLAIN", []string{"foo\x00bar\x00baz"}},
}
func TestAuth(t *testing.T) {
testLoop:
for i, test := range authTests {
name, resp, err := test.auth.Start(&ServerInfo{"testserver", true, nil})
if name != test.name {
t.Errorf("#%d got name %s, expected %s", i, name, test.name)
}
if !bytes.Equal(resp, []byte(test.responses[0])) {
t.Errorf("#%d got response %s, expected %s", i, resp, test.responses[0])
}
if err != nil {
t.Errorf("#%d error: %s", i, err.String())
}
for j := range test.challenges {
challenge := []byte(test.challenges[j])
expected := []byte(test.responses[j+1])
resp, err := test.auth.Next(challenge, true)
if err != nil {
t.Errorf("#%d error: %s", i, err.String())
continue testLoop
}
if !bytes.Equal(resp, expected) {
t.Errorf("#%d got %s, expected %s", i, resp, expected)
continue testLoop
}
}
}
}
type faker struct {
io.ReadWriter
}
func (f faker) Close() os.Error {
return nil
}
func TestBasic(t *testing.T) {
basicServer = strings.Join(strings.Split(basicServer, "\n", -1), "\r\n")
basicClient = strings.Join(strings.Split(basicClient, "\n", -1), "\r\n")
var cmdbuf bytes.Buffer
bcmdbuf := bufio.NewWriter(&cmdbuf)
var fake faker
fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(basicServer)), bcmdbuf)
c := &Client{Text: textproto.NewConn(fake)}
if err := c.helo(); err != nil {
t.Fatalf("HELO failed: %s", err.String())
}
if err := c.ehlo(); err == nil {
t.Fatalf("Expected first EHLO to fail")
}
if err := c.ehlo(); err != nil {
t.Fatalf("Second EHLO failed: %s", err.String())
}
if ok, args := c.Extension("aUtH"); !ok || args != "LOGIN PLAIN" {
t.Fatalf("Expected AUTH supported")
}
if ok, _ := c.Extension("DSN"); ok {
t.Fatalf("Shouldn't support DSN")
}
if err := c.Mail("user@gmail.com"); err == nil {
t.Fatalf("MAIL should require authentication")
}
if err := c.Verify("user1@gmail.com"); err == nil {
t.Fatalf("First VRFY: expected no verification")
}
if err := c.Verify("user2@gmail.com"); err != nil {
t.Fatalf("Second VRFY: expected verification, got %s", err)
}
// fake TLS so authentication won't complain
c.tls = true
c.serverName = "smtp.google.com"
if err := c.Auth(PlainAuth("", "user", "pass", "smtp.google.com")); err != nil {
t.Fatalf("AUTH failed: %s", err.String())
}
if err := c.Mail("user@gmail.com"); err != nil {
t.Fatalf("MAIL failed: %s", err.String())
}
if err := c.Rcpt("golang-nuts@googlegroups.com"); err != nil {
t.Fatalf("RCPT failed: %s", err.String())
}
msg := `From: user@gmail.com
To: golang-nuts@googlegroups.com
Subject: Hooray for Go
Line 1
.Leading dot line .
Goodbye.`
w, err := c.Data()
if err != nil {
t.Fatalf("DATA failed: %s", err.String())
}
if _, err := w.Write([]byte(msg)); err != nil {
t.Fatalf("Data write failed: %s", err.String())
}
if err := w.Close(); err != nil {
t.Fatalf("Bad data response: %s", err.String())
}
if err := c.Quit(); err != nil {
t.Fatalf("QUIT failed: %s", err.String())
}
bcmdbuf.Flush()
actualcmds := cmdbuf.String()
if basicClient != actualcmds {
t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, basicClient)
}
}
var basicServer = `250 mx.google.com at your service
502 Unrecognized command.
250-mx.google.com at your service
250-SIZE 35651584
250-AUTH LOGIN PLAIN
250 8BITMIME
530 Authentication required
252 Send some mail, I'll try my best
250 User is valid
235 Accepted
250 Sender OK
250 Receiver OK
354 Go ahead
250 Data OK
221 OK
`
var basicClient = `HELO localhost
EHLO localhost
EHLO localhost
MAIL FROM:<user@gmail.com> BODY=8BITMIME
VRFY user1@gmail.com
VRFY user2@gmail.com
AUTH PLAIN AHVzZXIAcGFzcw==
MAIL FROM:<user@gmail.com> BODY=8BITMIME
RCPT TO:<golang-nuts@googlegroups.com>
DATA
From: user@gmail.com
To: golang-nuts@googlegroups.com
Subject: Hooray for Go
Line 1
..Leading dot line .
Goodbye.
.
QUIT
`