/
ftp.go
73 lines (65 loc) · 1.76 KB
/
ftp.go
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/*-
* Copyright 2017 Square Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package starttls
import (
"bufio"
"crypto/tls"
"errors"
"fmt"
"net"
"strings"
)
func dumpAuthTLSFromFTP(dialer *net.Dialer, address string, config *tls.Config) (*tls.ConnectionState, error) {
c, err := dialer.Dial("tcp", address)
if err != nil {
return nil, err
}
conn := c.(*net.TCPConn)
status, err := readFTP(conn)
if err != nil {
return nil, err
}
if status != "220" {
return nil, fmt.Errorf("FTP server responded with status %s, was expecting 220", status)
}
fmt.Fprintf(conn, "AUTH TLS\r\n")
status, err = readFTP(conn)
if err != nil {
return nil, err
}
if status != "234" {
return nil, fmt.Errorf("FTP server responded with status %s, was expecting 234", status)
}
tlsConn := tls.Client(conn, config)
err = tlsConn.Handshake()
if err != nil {
return nil, err
}
state := tlsConn.ConnectionState()
return &state, nil
}
func readFTP(conn *net.TCPConn) (string, error) {
reader := bufio.NewReader(conn)
response, err := reader.ReadString('\n')
if err != nil {
return "", err
}
status := strings.Split(response, " ")
if len(status) == 0 {
return "", errors.New("garbled response from FTP server after AUTH TLS command")
}
return status[0], nil
}