1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
|
// Protocol132.cpp
// Implements the cProtocol132 class representing the release 1.3.2 protocol (#39)
#include "Globals.h"
#include "Protocol132.h"
#include "cRoot.h"
#include "cServer.h"
#include "cClientHandle.h"
#include "CryptoPP/osrng.h"
#define HANDLE_PACKET_READ(Proc, Type, Var) \
Type Var; \
{ \
if (!m_ReceivedData.Proc(Var)) \
{ \
return PARSE_INCOMPLETE; \
} \
}
typedef unsigned char Byte;
using namespace CryptoPP;
const int MAX_ENC_LEN = 512; // Maximum size of the encrypted message; should be 128, but who knows...
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// cProtocol132:
cProtocol132::cProtocol132(cClientHandle * a_Client) :
super(a_Client),
m_IsEncrypted(false)
{
}
void cProtocol132::DataReceived(const char * a_Data, int a_Size)
{
if (m_IsEncrypted)
{
byte Decrypted[512];
while (a_Size > 0)
{
int NumBytes = (a_Size > sizeof(Decrypted)) ? sizeof(Decrypted) : a_Size;
m_Decryptor.ProcessData(Decrypted, (byte *)a_Data, NumBytes);
super::DataReceived((const char *)Decrypted, NumBytes);
a_Size -= NumBytes;
a_Data += NumBytes;
}
}
else
{
super::DataReceived(a_Data, a_Size);
}
}
int cProtocol132::ParsePacket(unsigned char a_PacketType)
{
switch (a_PacketType)
{
default: return super::ParsePacket(a_PacketType); // off-load previously known packets into cProtocol125
case 0xcd: return ParseClientStatuses();
case 0xfc: return ParseEncryptionKeyResponse();
}
}
int cProtocol132::ParseHandshake(void)
{
HANDLE_PACKET_READ(ReadByte, Byte, ProtocolVersion);
HANDLE_PACKET_READ(ReadBEUTF16String16, AString, Username);
HANDLE_PACKET_READ(ReadBEUTF16String16, AString, ServerHost);
HANDLE_PACKET_READ(ReadBEInt, int, ServerPort);
m_Username = Username;
AString key;
CryptoPP::StringSink sink(key); // GCC won't allow inline instantiation in the following line, damned temporary refs
cRoot::Get()->GetServer()->GetPublicKey().Save(sink);
// Send a 0xFD Encryption Key Request http://wiki.vg/Protocol#Encryption_Key_Request_.280xFD.29
WriteByte((char)0xfd);
WriteString("MCServer");
WriteShort((short)key.size());
SendData(key.data(), key.size());
WriteShort(4);
WriteInt((int)this); // Using 'this' as the cryptographic nonce, so that we don't have to generate one each time :)
return PARSE_OK;
}
int cProtocol132::ParseLogin(void)
{
// Login packet not used in 1.3.2
return PARSE_ERROR;
}
int cProtocol132::ParseClientStatuses(void)
{
HANDLE_PACKET_READ(ReadByte, byte, Status);
// DEBUG:
// Kick the client, we don't have all the packets yet and sending wrong packets makes the client freeze
// m_Client->Kick("I don't speak your language (yet)");
// TODO:
// m_Client->HandleLogin(39, m_Username);
return PARSE_OK;
}
int cProtocol132::ParseEncryptionKeyResponse(void)
{
HANDLE_PACKET_READ(ReadBEShort, short, EncKeyLength);
AString EncKey;
if (!m_ReceivedData.ReadString(EncKey, EncKeyLength))
{
return PARSE_INCOMPLETE;
}
HANDLE_PACKET_READ(ReadBEShort, short, EncNonceLength);
AString EncNonce;
if (!m_ReceivedData.ReadString(EncNonce, EncNonceLength))
{
return PARSE_INCOMPLETE;
}
if ((EncKeyLength > MAX_ENC_LEN) || (EncNonceLength > MAX_ENC_LEN))
{
LOGD("Too long encryption");
m_Client->Kick("Hacked client");
return PARSE_OK;
}
HandleEncryptionKeyResponse(EncKey, EncNonce);
return PARSE_OK;
}
void cProtocol132::SendData(const char * a_Data, int a_Size)
{
if (m_IsEncrypted)
{
byte Encrypted[1024]; // Larger buffer, we may be sending lots of data (chunks)
while (a_Size > 0)
{
int NumBytes = (a_Size > sizeof(Encrypted)) ? sizeof(Encrypted) : a_Size;
m_Encryptor.ProcessData(Encrypted, (byte *)a_Data, NumBytes);
super::SendData((const char *)Encrypted, NumBytes);
a_Size -= NumBytes;
a_Data += NumBytes;
}
}
else
{
super::SendData(a_Data, a_Size);
}
}
void cProtocol132::HandleEncryptionKeyResponse(const AString & a_EncKey, const AString & a_EncNonce)
{
// Decrypt EncNonce using privkey
RSAES<PKCS1v15>::Decryptor rsaDecryptor(cRoot::Get()->GetServer()->GetPrivateKey());
AutoSeededRandomPool rng;
byte DecryptedNonce[MAX_ENC_LEN];
DecodingResult res = rsaDecryptor.Decrypt(rng, (const byte *)a_EncNonce.data(), a_EncNonce.size(), DecryptedNonce);
if (!res.isValidCoding || (res.messageLength != 4))
{
LOGD("Bad nonce length");
m_Client->Kick("Hacked client");
return;
}
if (ntohl(*((int *)DecryptedNonce)) != (unsigned)this)
{
LOGD("Bad nonce value");
m_Client->Kick("Hacked client");
return;
}
// Decrypt the symmetric encryption key using privkey:
byte DecryptedKey[MAX_ENC_LEN];
res = rsaDecryptor.Decrypt(rng, (const byte *)a_EncKey.data(), a_EncKey.size(), DecryptedKey);
if (!res.isValidCoding || (res.messageLength != 16))
{
LOGD("Bad key length");
m_Client->Kick("Hacked client");
return;
}
// Send encryption key response:
WriteByte((char)0xfc);
WriteShort(0);
WriteShort(0);
StartEncryption(DecryptedKey);
return;
}
void cProtocol132::StartEncryption(const byte * a_Key)
{
m_Encryptor.SetKey(a_Key, 16, MakeParameters(Name::IV(), ConstByteArrayParameter(a_Key, 16))(Name::FeedbackSize(), 1));
m_Decryptor.SetKey(a_Key, 16, MakeParameters(Name::IV(), ConstByteArrayParameter(a_Key, 16))(Name::FeedbackSize(), 1));
m_IsEncrypted = true;
}
|
