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80 lines
2.0 KiB
Go
80 lines
2.0 KiB
Go
package client
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import (
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"encoding/binary"
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"github.com/cbeuw/Cloak/internal/util"
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"net"
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log "github.com/sirupsen/logrus"
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)
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type Browser interface {
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composeClientHello(*State) ([]byte, []byte)
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}
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func makeServerName(serverName string) []byte {
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serverNameListLength := make([]byte, 2)
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binary.BigEndian.PutUint16(serverNameListLength, uint16(len(serverName)+3))
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serverNameType := []byte{0x00} // host_name
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serverNameLength := make([]byte, 2)
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binary.BigEndian.PutUint16(serverNameLength, uint16(len(serverName)))
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ret := make([]byte, 2+1+2+len(serverName))
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copy(ret[0:2], serverNameListLength)
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copy(ret[2:3], serverNameType)
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copy(ret[3:5], serverNameLength)
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copy(ret[5:], serverName)
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return ret
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}
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// addExtensionRecord, add type, length to extension data
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func addExtRec(typ []byte, data []byte) []byte {
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length := make([]byte, 2)
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binary.BigEndian.PutUint16(length, uint16(len(data)))
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ret := make([]byte, 2+2+len(data))
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copy(ret[0:2], typ)
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copy(ret[2:4], length)
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copy(ret[4:], data)
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return ret
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}
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// composeClientHello composes ClientHello with record layer
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func composeClientHello(sta *State) ([]byte, []byte) {
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ch, sharedSecret := sta.Browser.composeClientHello(sta)
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return util.AddRecordLayer(ch, []byte{0x16}, []byte{0x03, 0x01}), sharedSecret
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}
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func PrepareConnection(sta *State, conn net.Conn) (sessionKey []byte, err error) {
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clientHello, sharedSecret := composeClientHello(sta)
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_, err = conn.Write(clientHello)
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if err != nil {
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return
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}
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log.Trace("client hello sent successfully")
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buf := make([]byte, 1024)
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log.Trace("waiting for ServerHello")
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_, err = util.ReadTLS(conn, buf)
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if err != nil {
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return
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}
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encrypted := append(buf[11:43], buf[89:121]...)
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nonce := encrypted[0:12]
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ciphertext := encrypted[12:60]
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sessionKey, err = util.AESGCMDecrypt(nonce, sharedSecret, ciphertext)
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if err != nil {
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return
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}
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for i := 0; i < 2; i++ {
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// ChangeCipherSpec and EncryptedCert (in the format of application data)
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_, err = util.ReadTLS(conn, buf)
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if err != nil {
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return
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}
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}
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return sessionKey, nil
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}
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