src/pkg/smtp/smtp.go - go - Git at Google

 // 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.Contains(msg, "ESMTP") {
 		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(config *tls.Config) os.Error {
 	_, _, err := c.cmd(220, "STARTTLS")
 	if err != nil {
 		return err
 	}
 	c.conn = tls.Client(c.conn, config)
 	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(nil); 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()
 }
	// 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.Contains(msg, "ESMTP") {
	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(config tls.Config) os.Error {
	_, _, err := c.cmd(220, "STARTTLS")
	if err != nil {
	return err
	}
	c.conn = tls.Client(c.conn, config)
	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(nil); 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()
	}