text: // Copyright 2011 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package ssh
  
  import (
  	"bytes"
  	"crypto"
  	"crypto/aes"
  	"crypto/rand"
  	"testing"
  )
  
  func TestDefaultCiphersExist(t *testing.T) {
  	for _, cipherAlgo := range supportedCiphers {
  		if _, ok := cipherModes[cipherAlgo]; !ok {
  			t.Errorf("default cipher %q is unknown", cipherAlgo)
  		}
  	}
  }
  
  func TestPacketCiphers(t *testing.T) {
  	// Still test aes128cbc cipher although it's commented out.
  	cipherModes[aes128cbcID] = &streamCipherMode{16, aes.BlockSize, 0, nil}
  	defer delete(cipherModes, aes128cbcID)
  
  	for cipher := range cipherModes {
  		kr := &kexResult{Hash: crypto.SHA1}
  		algs := directionAlgorithms{
  			Cipher:      cipher,
  			MAC:         "hmac-sha1",
  			Compression: "none",
  		}
  		client, err := newPacketCipher(clientKeys, algs, kr)
  		if err != nil {
  			t.Errorf("newPacketCipher(client, %q): %v", cipher, err)
  			continue
  		}
  		server, err := newPacketCipher(clientKeys, algs, kr)
  		if err != nil {
  			t.Errorf("newPacketCipher(client, %q): %v", cipher, err)
  			continue
  		}
  
  		want := "bla bla"
  		input := []byte(want)
  		buf := &bytes.Buffer{}
  		if err := client.writePacket(0, buf, rand.Reader, input); err != nil {
  			t.Errorf("writePacket(%q): %v", cipher, err)
  			continue
  		}
  
  		packet, err := server.readPacket(0, buf)
  		if err != nil {
  			t.Errorf("readPacket(%q): %v", cipher, err)
  			continue
  		}
  
  		if string(packet) != want {
  			t.Errorf("roundtrip(%q): got %q, want %q", cipher, packet, want)
  		}
  	}
  }
  
  func TestCBCOracleCounterMeasure(t *testing.T) {
  	cipherModes[aes128cbcID] = &streamCipherMode{16, aes.BlockSize, 0, nil}
  	defer delete(cipherModes, aes128cbcID)
  
  	kr := &kexResult{Hash: crypto.SHA1}
  	algs := directionAlgorithms{
  		Cipher:      aes128cbcID,
  		MAC:         "hmac-sha1",
  		Compression: "none",
  	}
  	client, err := newPacketCipher(clientKeys, algs, kr)
  	if err != nil {
  		t.Fatalf("newPacketCipher(client): %v", err)
  	}
  
  	want := "bla bla"
  	input := []byte(want)
  	buf := &bytes.Buffer{}
  	if err := client.writePacket(0, buf, rand.Reader, input); err != nil {
  		t.Errorf("writePacket: %v", err)
  	}
  
  	packetSize := buf.Len()
  	buf.Write(make([]byte, 2*maxPacket))
  
  	// We corrupt each byte, but this usually will only test the
  	// 'packet too large' or 'MAC failure' cases.
  	lastRead := -1
  	for i := 0; i < packetSize; i++ {
  		server, err := newPacketCipher(clientKeys, algs, kr)
  		if err != nil {
  			t.Fatalf("newPacketCipher(client): %v", err)
  		}
  
  		fresh := &bytes.Buffer{}
  		fresh.Write(buf.Bytes())
  		fresh.Bytes()[i] ^= 0x01
  
  		before := fresh.Len()
  		_, err = server.readPacket(0, fresh)
  		if err == nil {
  			t.Errorf("corrupt byte %d: readPacket succeeded ", i)
  			continue
  		}
  		if _, ok := err.(cbcError); !ok {
  			t.Errorf("corrupt byte %d: got %v (%T), want cbcError", i, err, err)
  			continue
  		}
  
  		after := fresh.Len()
  		bytesRead := before - after
  		if bytesRead < maxPacket {
  			t.Errorf("corrupt byte %d: read %d bytes, want more than %d", i, bytesRead, maxPacket)
  			continue
  		}
  
  		if i > 0 && bytesRead != lastRead {
  			t.Errorf("corrupt byte %d: read %d bytes, want %d bytes read", i, bytesRead, lastRead)
  		}
  		lastRead = bytesRead
  	}
  }
  