148 lines
3.6 KiB
Go
148 lines
3.6 KiB
Go
// Copyright (C) 2014 The Syncthing Authors.
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//
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// This program is free software: you can redistribute it and/or modify it
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// under the terms of the GNU General Public License as published by the Free
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// Software Foundation, either version 3 of the License, or (at your option)
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// any later version.
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//
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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// more details.
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//
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// You should have received a copy of the GNU General Public License along
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// with this program. If not, see <http://www.gnu.org/licenses/>.
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package main
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import (
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"bufio"
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"crypto/rand"
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"crypto/rsa"
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"crypto/sha256"
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"crypto/tls"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/binary"
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"encoding/pem"
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"io"
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"math/big"
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mr "math/rand"
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"net"
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"os"
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"path/filepath"
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"time"
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)
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const (
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tlsRSABits = 3072
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tlsName = "syncthing"
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)
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func loadCert(dir string, prefix string) (tls.Certificate, error) {
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cf := filepath.Join(dir, prefix+"cert.pem")
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kf := filepath.Join(dir, prefix+"key.pem")
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return tls.LoadX509KeyPair(cf, kf)
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}
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func certSeed(bs []byte) int64 {
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hf := sha256.New()
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hf.Write(bs)
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id := hf.Sum(nil)
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return int64(binary.BigEndian.Uint64(id))
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}
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func newCertificate(dir string, prefix string) {
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l.Infoln("Generating RSA key and certificate...")
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priv, err := rsa.GenerateKey(rand.Reader, tlsRSABits)
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if err != nil {
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l.Fatalln("generate key:", err)
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}
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notBefore := time.Now()
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notAfter := time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)
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template := x509.Certificate{
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SerialNumber: new(big.Int).SetInt64(mr.Int63()),
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Subject: pkix.Name{
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CommonName: tlsName,
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},
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NotBefore: notBefore,
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NotAfter: notAfter,
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KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
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ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth, x509.ExtKeyUsageClientAuth},
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BasicConstraintsValid: true,
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}
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derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
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if err != nil {
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l.Fatalln("create cert:", err)
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}
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certOut, err := os.Create(filepath.Join(dir, prefix+"cert.pem"))
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if err != nil {
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l.Fatalln("save cert:", err)
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}
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err = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
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if err != nil {
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l.Fatalln("save cert:", err)
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}
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err = certOut.Close()
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if err != nil {
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l.Fatalln("save cert:", err)
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}
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keyOut, err := os.OpenFile(filepath.Join(dir, prefix+"key.pem"), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
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if err != nil {
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l.Fatalln("save key:", err)
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}
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err = pem.Encode(keyOut, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)})
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if err != nil {
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l.Fatalln("save key:", err)
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}
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err = keyOut.Close()
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if err != nil {
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l.Fatalln("save key:", err)
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}
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}
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type DowngradingListener struct {
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net.Listener
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TLSConfig *tls.Config
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}
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type WrappedConnection struct {
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io.Reader
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net.Conn
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}
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func (l *DowngradingListener) Accept() (net.Conn, error) {
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conn, err := l.Listener.Accept()
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if err != nil {
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return nil, err
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}
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br := bufio.NewReader(conn)
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bs, err := br.Peek(1)
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if err != nil {
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// We hit a read error here, but the Accept() call succeeded so we must not return an error.
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// We return the connection as is and let whoever tries to use it deal with the error.
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return conn, nil
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}
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wrapper := &WrappedConnection{br, conn}
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// 0x16 is the first byte of a TLS handshake
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if bs[0] == 0x16 {
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return tls.Server(wrapper, l.TLSConfig), nil
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}
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return wrapper, nil
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}
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func (c *WrappedConnection) Read(b []byte) (n int, err error) {
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return c.Reader.Read(b)
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}
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