67 lines
1.4 KiB
Go
67 lines
1.4 KiB
Go
package gomail
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import (
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"bytes"
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"errors"
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"fmt"
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"net/smtp"
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)
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// plainAuth is an smtp.Auth that implements the PLAIN authentication mechanism.
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// It fallbacks to the LOGIN mechanism if it is the only mechanism advertised
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// by the server.
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type plainAuth struct {
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username string
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password string
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host string
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login bool
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}
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func (a *plainAuth) Start(server *smtp.ServerInfo) (string, []byte, error) {
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if server.Name != a.host {
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return "", nil, errors.New("gomail: wrong host name")
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}
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var plain, login bool
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for _, a := range server.Auth {
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switch a {
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case "PLAIN":
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plain = true
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case "LOGIN":
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login = true
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}
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}
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if !server.TLS && !plain && !login {
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return "", nil, errors.New("gomail: unencrypted connection")
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}
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if !plain && login {
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a.login = true
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return "LOGIN", nil, nil
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}
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return "PLAIN", []byte("\x00" + a.username + "\x00" + a.password), nil
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}
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func (a *plainAuth) Next(fromServer []byte, more bool) ([]byte, error) {
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if !a.login {
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if more {
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return nil, errors.New("gomail: unexpected server challenge")
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}
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return nil, nil
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}
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if !more {
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return nil, nil
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}
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switch {
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case bytes.Equal(fromServer, []byte("Username:")):
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return []byte(a.username), nil
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case bytes.Equal(fromServer, []byte("Password:")):
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return []byte(a.password), nil
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default:
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return nil, fmt.Errorf("gomail: unexpected server challenge: %s", fromServer)
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}
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}
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