mirror of
https://github.com/ergochat/ergo.git
synced 2024-12-24 19:52:35 +01:00
111 lines
3.8 KiB
Go
111 lines
3.8 KiB
Go
// 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
|
|
}
|