--- /dev/null
+// 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
+}
--- /dev/null
+// 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()
+}
--- /dev/null
+// 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
+`