48 lines
1.4 KiB
Go
48 lines
1.4 KiB
Go
package main
|
|
|
|
import (
|
|
"bytes"
|
|
"crypto/tls"
|
|
"io"
|
|
"net"
|
|
"time"
|
|
)
|
|
|
|
func getServerNameExtension(connection net.Conn) (string, io.Reader, error) {
|
|
peekedBytes := new(bytes.Buffer)
|
|
sni, err := readServerNameExtension(io.TeeReader(connection, peekedBytes))
|
|
if err != nil {
|
|
return "", nil, err
|
|
}
|
|
|
|
return sni, io.MultiReader(peekedBytes, connection), nil
|
|
}
|
|
|
|
type readOnlyConn struct {
|
|
reader io.Reader
|
|
}
|
|
|
|
func (conn readOnlyConn) Read(p []byte) (int, error) { return conn.reader.Read(p) }
|
|
func (conn readOnlyConn) Write(p []byte) (int, error) { return 0, io.ErrClosedPipe }
|
|
func (conn readOnlyConn) Close() error { return nil }
|
|
func (conn readOnlyConn) LocalAddr() net.Addr { return nil }
|
|
func (conn readOnlyConn) RemoteAddr() net.Addr { return nil }
|
|
func (conn readOnlyConn) SetDeadline(t time.Time) error { return nil }
|
|
func (conn readOnlyConn) SetReadDeadline(t time.Time) error { return nil }
|
|
func (conn readOnlyConn) SetWriteDeadline(t time.Time) error { return nil }
|
|
|
|
func readServerNameExtension(reader io.Reader) (string, error) {
|
|
var sni string
|
|
|
|
if err := tls.Server(readOnlyConn{reader: reader}, &tls.Config{
|
|
GetConfigForClient: func(clientHello *tls.ClientHelloInfo) (*tls.Config, error) {
|
|
sni = clientHello.ServerName
|
|
return nil, nil
|
|
},
|
|
}).Handshake(); sni == "" {
|
|
return "", err
|
|
}
|
|
|
|
return sni, nil
|
|
}
|