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clean up encryption code some

This commit is contained in:
Arvid Norberg 2011-08-29 02:00:17 +00:00
parent 0a250c8f36
commit ec74d500a4
4 changed files with 73 additions and 87 deletions
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12
include/libtorrent/bt_peer_connection.hpp
View File

@ -284,7 +284,7 @@ namespace libtorrent
// stream key (info hash of attached torrent)
// secret is the DH shared secret
// initializes m_rc4_handler
// initializes m_enc_handler
void init_pe_rc4_handler(char const* secret, sha1_hash const& stream_key);
public:
@ -298,8 +298,8 @@ public:
void append_send_buffer(char* buffer, int size, Destructor const& destructor)
{
#ifndef TORRENT_DISABLE_ENCRYPTION
if (m_rc4_encrypted)
m_rc4_handler->encrypt(buffer, size);
if (m_enc_handler)
m_enc_handler->encrypt(buffer, size);
#endif
peer_connection::append_send_buffer(buffer, size, destructor, true);
}
@ -414,14 +414,14 @@ private:
int m_sync_bytes_read;
// initialized during write_pe1_2_dhkey, and destroyed on
// creation of m_rc4_handler. Cannot reinitialize once
// creation of m_enc_handler. Cannot reinitialize once
// initialized.
boost::scoped_ptr<dh_key_exchange> m_dh_key_exchange;
// if RC4 is negotiated, this is used for
// if encryption is negotiated, this is used for
// encryption/decryption during the entire session. Destroyed
// if plaintext is selected
boost::scoped_ptr<rc4_handler> m_rc4_handler;
boost::scoped_ptr<encryption_handler> m_enc_handler;
// (outgoing only) synchronize verification constant with
// remote peer, this will hold rc4_decrypt(vc). Destroyed

10
include/libtorrent/pe_crypto.hpp
View File

@ -85,7 +85,15 @@ namespace libtorrent
sha1_hash m_xor_mask;
};
class rc4_handler // Non copyable
struct encryption_handler
{
virtual void set_incoming_key(unsigned char const* key, int len) = 0;
virtual void set_outgoing_key(unsigned char const* key, int len) = 0;
virtual void encrypt(char* pos, int len) = 0;
virtual void decrypt(char* pos, int len) = 0;
};
struct rc4_handler : encryption_handler
{
public:
// Input longkeys must be 20 bytes

6
include/libtorrent/session_settings.hpp
View File

@ -1161,9 +1161,9 @@ namespace libtorrent
enum enc_level
{
plaintext, // use only plaintext encryption
rc4, // use only rc4 encryption
both // allow both
plaintext = 1, // use only plaintext encryption
rc4 = 2, // use only rc4 encryption
both = 3 // allow both
};
enc_policy out_enc_policy;

132
src/bt_peer_connection.cpp
View File

@ -518,7 +518,7 @@ namespace libtorrent
#endif
write_pe_vc_cryptofield(ptr, encrypt_size, crypto_provide, pad_size);
m_rc4_handler->encrypt(ptr, encrypt_size);
m_enc_handler->encrypt(ptr, encrypt_size);
send_buffer(msg, sizeof(msg) - 512 + pad_size);
}
@ -538,7 +538,7 @@ namespace libtorrent
char msg[512 + 8 + 4 + 2];
write_pe_vc_cryptofield(msg, sizeof(msg), crypto_select, pad_size);
m_rc4_handler->encrypt(msg, buf_size);
m_enc_handler->encrypt(msg, buf_size);
send_buffer(msg, buf_size);
// encryption method has been negotiated
@ -613,11 +613,12 @@ namespace libtorrent
h.update((char const*)stream_key.begin(), 20);
const sha1_hash remote_key = h.final();
TORRENT_ASSERT(!m_rc4_handler.get());
m_rc4_handler.reset(new (std::nothrow) rc4_handler);
m_rc4_handler->set_incoming_key(&remote_key[0], 20);
m_rc4_handler->set_outgoing_key(&local_key[0], 20);
if (!m_rc4_handler)
TORRENT_ASSERT(!m_enc_handler.get());
m_enc_handler.reset(new (std::nothrow) rc4_handler);
m_enc_handler->set_incoming_key(&remote_key[0], 20);
m_enc_handler->set_outgoing_key(&local_key[0], 20);
if (!m_enc_handler)
{
disconnect(errors::no_memory);
return;
@ -663,7 +664,7 @@ namespace libtorrent
if (m_encrypted && m_rc4_encrypted)
{
fun = encrypt;
userdata = m_rc4_handler.get();
userdata = m_enc_handler.get();
}
#endif
@ -2362,8 +2363,8 @@ namespace libtorrent
if (m_rc4_encrypted && m_encrypted)
{
std::pair<buffer::interval, buffer::interval> wr_buf = wr_recv_buffers(bytes_transferred);
m_rc4_handler->decrypt(wr_buf.first.begin, wr_buf.first.left());
if (wr_buf.second.left()) m_rc4_handler->decrypt(wr_buf.second.begin, wr_buf.second.left());
m_enc_handler->decrypt(wr_buf.first.begin, wr_buf.first.left());
if (wr_buf.second.left()) m_enc_handler->decrypt(wr_buf.second.begin, wr_buf.second.left());
}
#endif
@ -2555,7 +2556,7 @@ namespace libtorrent
}
}
if (!m_rc4_handler.get())
if (!m_enc_handler.get())
{
disconnect(errors::invalid_info_hash, 1);
return;
@ -2563,7 +2564,7 @@ namespace libtorrent
// verify constant
buffer::interval wr_recv_buf = wr_recv_buffer();
m_rc4_handler->decrypt(wr_recv_buf.begin + 20, 8);
m_enc_handler->decrypt(wr_recv_buf.begin + 20, 8);
wr_recv_buf.begin += 28;
const char sh_vc[] = {0,0,0,0, 0,0,0,0};
@ -2608,7 +2609,7 @@ namespace libtorrent
return;
}
std::fill(m_sync_vc.get(), m_sync_vc.get() + 8, 0);
m_rc4_handler->decrypt(m_sync_vc.get(), 8);
m_enc_handler->decrypt(m_sync_vc.get(), 8);
}
TORRENT_ASSERT(m_sync_vc.get());
@ -2666,7 +2667,7 @@ namespace libtorrent
if (!packet_finished()) return;
buffer::interval wr_buf = wr_recv_buffer();
m_rc4_handler->decrypt(wr_buf.begin, packet_size());
m_enc_handler->decrypt(wr_buf.begin, packet_size());
recv_buffer = receive_buffer();
@ -2681,80 +2682,57 @@ namespace libtorrent
if (!is_local())
{
int crypto_select = 0;
// select a crypto method
switch (m_ses.get_pe_settings().allowed_enc_level)
int allowed_encryption = m_ses.get_pe_settings().allowed_enc_level;
int crypto_select = crypto_field & allowed_encryption;
// when prefer_rc4 is set, keep the most significant bit
// otherwise keep the least significant one
if (m_ses.get_pe_settings().prefer_rc4)
{
case pe_settings::plaintext:
if (!(crypto_field & 0x01))
int mask = INT_MAX;
while (crypto_select & (mask << 1))
{
disconnect(errors::no_plaintext_mode, 1);
return;
mask <<= 1;
crypto_select = crypto_select & mask;
}
crypto_select = 0x01;
break;
case pe_settings::rc4:
if (!(crypto_field & 0x02))
}
else
{
int mask = INT_MAX;
while (crypto_select & (mask >> 1))
{
disconnect(errors::no_rc4_mode, 1);
return;
mask >>= 1;
crypto_select = crypto_select & mask;
}
crypto_select = 0x02;
break;
case pe_settings::both:
if (m_ses.get_pe_settings().prefer_rc4)
{
if (crypto_field & 0x02)
crypto_select = 0x02;
else if (crypto_field & 0x01)
crypto_select = 0x01;
}
else
{
if (crypto_field & 0x01)
crypto_select = 0x01;
else if (crypto_field & 0x02)
crypto_select = 0x02;
}
if (!crypto_select)
{
}
if (crypto_select == 0)
{
disconnect(errors::unsupported_encryption_mode, 1);
return;
}
break;
} // switch
}
// write the pe4 step
write_pe4_sync(crypto_select);
}
else // is_local()
{
// check if crypto select is valid
pe_settings::enc_level const& allowed_enc_level = m_ses.get_pe_settings().allowed_enc_level;
int allowed_encryption = m_ses.get_pe_settings().allowed_enc_level;
if (crypto_field == 0x02)
{
if (allowed_enc_level == pe_settings::plaintext)
{
disconnect(errors::unsupported_encryption_mode_selected, 2);
return;
}
m_rc4_encrypted = true;
}
else if (crypto_field == 0x01)
{
if (allowed_enc_level == pe_settings::rc4)
{
disconnect(errors::unsupported_encryption_mode_selected, 2);
return;
}
m_rc4_encrypted = false;
}
else
crypto_field &= allowed_encryption;
if (crypto_field == 0)
{
// we don't allow any of the offered encryption levels
disconnect(errors::unsupported_encryption_mode_selected, 2);
return;
}
if (crypto_field == pe_settings::plaintext)
m_rc4_encrypted = false;
else if (crypto_field == pe_settings::rc4)
m_rc4_encrypted = true;
}
int len_pad = detail::read_int16(recv_buffer.begin);
@ -2789,7 +2767,7 @@ namespace libtorrent
int pad_size = is_local() ? packet_size() : packet_size() - 2;
buffer::interval wr_buf = wr_recv_buffer();
m_rc4_handler->decrypt(wr_buf.begin, packet_size());
m_enc_handler->decrypt(wr_buf.begin, packet_size());
recv_buffer = receive_buffer();
@ -2838,7 +2816,7 @@ namespace libtorrent
// ia is always rc4, so decrypt it
buffer::interval wr_buf = wr_recv_buffer();
m_rc4_handler->decrypt(wr_buf.begin, packet_size());
m_enc_handler->decrypt(wr_buf.begin, packet_size());
#ifdef TORRENT_VERBOSE_LOGGING
peer_log("*** decrypted ia : %d bytes", packet_size());
@ -2846,13 +2824,13 @@ namespace libtorrent
if (!m_rc4_encrypted)
{
m_rc4_handler.reset();
m_enc_handler.reset();
#ifdef TORRENT_VERBOSE_LOGGING
peer_log("*** destroyed rc4 keys");
#endif
}
// everything that arrives after this is Encrypt2
// everything that arrives after this is encrypted
m_encrypted = true;
m_state = read_protocol_identifier;
@ -2870,16 +2848,16 @@ namespace libtorrent
{
buffer::interval wr_buf = wr_recv_buffer();
wr_buf.begin += packet_size();
m_rc4_handler->decrypt(wr_buf.begin, wr_buf.left());
m_enc_handler->decrypt(wr_buf.begin, wr_buf.left());
#ifdef TORRENT_VERBOSE_LOGGING
peer_log("*** decrypted remaining %d bytes", wr_buf.left());
#endif
}
else // !m_rc4_encrypted
{
m_rc4_handler.reset();
m_enc_handler.reset();
#ifdef TORRENT_VERBOSE_LOGGING
peer_log("*** destroyed rc4 keys");
peer_log("*** destroyed encryption handler");
#endif
}
@ -3341,7 +3319,7 @@ namespace libtorrent
TORRENT_ASSERT( (bool(m_state != read_pe_dhkey) || m_dh_key_exchange.get())
|| !is_local());
TORRENT_ASSERT(!m_rc4_encrypted || m_rc4_handler.get());
TORRENT_ASSERT(!m_rc4_encrypted || m_enc_handler.get());
#endif
if (!in_handshake())
{