From 6e630a0b5c136113a8480b7e91095eb6e95de501 Mon Sep 17 00:00:00 2001 From: Shivaram Lingamneni Date: Thu, 2 Apr 2020 23:46:25 -0400 Subject: [PATCH] add the smtp code from the go 1.14.1 release --- irc/smtp/LICENSE | 27 +++ irc/smtp/auth.go | 110 ++++++++++++ irc/smtp/smtp.go | 430 +++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 567 insertions(+) create mode 100644 irc/smtp/LICENSE create mode 100644 irc/smtp/auth.go create mode 100644 irc/smtp/smtp.go diff --git a/irc/smtp/LICENSE b/irc/smtp/LICENSE new file mode 100644 index 00000000..6a66aea5 --- /dev/null +++ b/irc/smtp/LICENSE @@ -0,0 +1,27 @@ +Copyright (c) 2009 The Go Authors. All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are +met: + + * Redistributions of source code must retain the above copyright +notice, this list of conditions and the following disclaimer. + * Redistributions in binary form must reproduce the above +copyright notice, this list of conditions and the following disclaimer +in the documentation and/or other materials provided with the +distribution. + * Neither the name of Google Inc. nor the names of its +contributors may be used to endorse or promote products derived from +this software without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/irc/smtp/auth.go b/irc/smtp/auth.go new file mode 100644 index 00000000..fd1a472f --- /dev/null +++ b/irc/smtp/auth.go @@ -0,0 +1,110 @@ +// 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 ( + "crypto/hmac" + "crypto/md5" + "errors" + "fmt" +) + +// 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 error, the SMTP client aborts + // the authentication attempt and closes the connection. + Start(server *ServerInfo) (proto string, toServer []byte, err 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 error, the SMTP client aborts + // the authentication attempt and closes the connection. + Next(fromServer []byte, more bool) (toServer []byte, err 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 to host and act as identity. +// Usually identity should be the empty string, to act as username. +// +// PlainAuth will only send the credentials if the connection is using TLS +// or is connected to localhost. Otherwise authentication will fail with an +// error, without sending the credentials. +func PlainAuth(identity, username, password, host string) Auth { + return &plainAuth{identity, username, password, host} +} + +func isLocalhost(name string) bool { + return name == "localhost" || name == "127.0.0.1" || name == "::1" +} + +func (a *plainAuth) Start(server *ServerInfo) (string, []byte, error) { + // Must have TLS, or else localhost server. + // Note: If TLS is not true, then we can't trust ANYTHING in ServerInfo. + // In particular, it doesn't matter if the server advertises PLAIN auth. + // That might just be the attacker saying + // "it's ok, you can trust me with your password." + if !server.TLS && !isLocalhost(server.Name) { + return "", nil, errors.New("unencrypted connection") + } + if server.Name != a.host { + return "", nil, errors.New("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, error) { + if more { + // We've already sent everything. + return nil, errors.New("unexpected server challenge") + } + return nil, nil +} + +type cramMD5Auth struct { + username, secret string +} + +// CRAMMD5Auth returns an Auth that implements the CRAM-MD5 authentication +// mechanism as defined in RFC 2195. +// The returned Auth uses the given username and secret to authenticate +// to the server using the challenge-response mechanism. +func CRAMMD5Auth(username, secret string) Auth { + return &cramMD5Auth{username, secret} +} + +func (a *cramMD5Auth) Start(server *ServerInfo) (string, []byte, error) { + return "CRAM-MD5", nil, nil +} + +func (a *cramMD5Auth) Next(fromServer []byte, more bool) ([]byte, error) { + if more { + d := hmac.New(md5.New, []byte(a.secret)) + d.Write(fromServer) + s := make([]byte, 0, d.Size()) + return []byte(fmt.Sprintf("%s %x", a.username, d.Sum(s))), nil + } + return nil, nil +} diff --git a/irc/smtp/smtp.go b/irc/smtp/smtp.go new file mode 100644 index 00000000..e4e12ae5 --- /dev/null +++ b/irc/smtp/smtp.go @@ -0,0 +1,430 @@ +// 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. +// +// The smtp package is frozen and is not accepting new features. +// Some external packages provide more functionality. See: +// +// https://godoc.org/?q=smtp +package smtp + +import ( + "crypto/tls" + "encoding/base64" + "errors" + "fmt" + "io" + "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 + 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. +// The addr must include a port, as in "mail.example.com:smtp". +func Dial(addr string) (*Client, error) { + conn, err := net.Dial("tcp", addr) + if err != nil { + return nil, err + } + host, _, _ := net.SplitHostPort(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, error) { + text := textproto.NewConn(conn) + _, _, err := text.ReadResponse(220) + if err != nil { + text.Close() + return nil, err + } + c := &Client{Text: text, conn: conn, serverName: host, localName: "localhost"} + _, c.tls = conn.(*tls.Conn) + return c, nil +} + +// Close closes the connection. +func (c *Client) Close() error { + return c.Text.Close() +} + +// 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 err := validateLine(localName); err != nil { + return err + } + if c.didHello { + return errors.New("smtp: Hello called after other methods") + } + c.localName = localName + return c.hello() +} + +// 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, 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() error { + c.ext = nil + _, _, 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 %s", c.localName) + if err != nil { + return err + } + ext := make(map[string]string) + extList := strings.Split(msg, "\n") + if len(extList) > 1 { + extList = extList[1:] + for _, line := range extList { + args := strings.SplitN(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, " ") + } + 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) error { + if err := c.hello(); err != nil { + return err + } + _, _, 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() +} + +// TLSConnectionState returns the client's TLS connection state. +// The return values are their zero values if StartTLS did +// not succeed. +func (c *Client) TLSConnectionState() (state tls.ConnectionState, ok bool) { + tc, ok := c.conn.(*tls.Conn) + if !ok { + return + } + return tc.ConnectionState(), true +} + +// 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) error { + if err := validateLine(addr); err != nil { + return err + } + if err := c.hello(); err != nil { + return err + } + _, _, 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) 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 { + c.Quit() + return err + } + resp64 := make([]byte, encoding.EncodedLen(len(resp))) + encoding.Encode(resp64, resp) + code, msg64, err := c.cmd(0, strings.TrimSpace(fmt.Sprintf("AUTH %s %s", mech, resp64))) + for err == nil { + var msg []byte + switch code { + case 334: + msg, err = encoding.DecodeString(msg64) + case 235: + // the last message isn't base64 because it isn't a challenge + msg = []byte(msg64) + default: + err = &textproto.Error{Code: code, Msg: msg64} + } + if err == nil { + 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) error { + if err := validateLine(from); err != nil { + return err + } + if err := c.hello(); err != nil { + return err + } + 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) error { + if err := validateLine(to); err != nil { + return err + } + _, _, err := c.cmd(25, "RCPT TO:<%s>", to) + return err +} + +type dataCloser struct { + c *Client + io.WriteCloser +} + +func (d *dataCloser) Close() 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 mail headers and body. 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, error) { + _, _, err := c.cmd(354, "DATA") + if err != nil { + return nil, err + } + return &dataCloser{c, c.Text.DotWriter()}, nil +} + +var testHookStartTLS func(*tls.Config) // nil, except for tests + +// SendMail connects to the server at addr, switches to TLS if +// possible, authenticates with the optional mechanism a if possible, +// and then sends an email from address from, to addresses to, with +// message msg. +// The addr must include a port, as in "mail.example.com:smtp". +// +// The addresses in the to parameter are the SMTP RCPT addresses. +// +// The msg parameter should be an RFC 822-style email with headers +// first, a blank line, and then the message body. The lines of msg +// should be CRLF terminated. The msg headers should usually include +// fields such as "From", "To", "Subject", and "Cc". Sending "Bcc" +// messages is accomplished by including an email address in the to +// parameter but not including it in the msg headers. +// +// The SendMail function and the net/smtp package are low-level +// mechanisms and provide no support for DKIM signing, MIME +// attachments (see the mime/multipart package), or other mail +// functionality. Higher-level packages exist outside of the standard +// library. +func SendMail(addr string, a Auth, from string, to []string, msg []byte) error { + if err := validateLine(from); err != nil { + return err + } + for _, recp := range to { + if err := validateLine(recp); err != nil { + return err + } + } + c, err := Dial(addr) + if err != nil { + return err + } + defer c.Close() + if err = c.hello(); err != nil { + return err + } + if ok, _ := c.Extension("STARTTLS"); ok { + config := &tls.Config{ServerName: c.serverName} + if testHookStartTLS != nil { + testHookStartTLS(config) + } + if err = c.StartTLS(config); err != nil { + return err + } + } + if a != nil && c.ext != nil { + if _, ok := c.ext["AUTH"]; !ok { + return errors.New("smtp: server doesn't support AUTH") + } + 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 err := c.hello(); err != nil { + return false, "" + } + 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() error { + if err := c.hello(); err != nil { + return err + } + _, _, err := c.cmd(250, "RSET") + return err +} + +// Noop sends the NOOP command to the server. It does nothing but check +// that the connection to the server is okay. +func (c *Client) Noop() error { + if err := c.hello(); err != nil { + return err + } + _, _, err := c.cmd(250, "NOOP") + 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 + } + return c.Text.Close() +} + +// validateLine checks to see if a line has CR or LF as per RFC 5321 +func validateLine(line string) error { + if strings.ContainsAny(line, "\n\r") { + return errors.New("smtp: A line must not contain CR or LF") + } + return nil +}