merged RC_1_2 into RC_2_0

Jamfile

@@ -153,8 +153,7 @@ rule linking ( properties * )
 		result += <framework>CoreFoundation <framework>SystemConfiguration ;
 	}
 
-	if ( <toolset>gcc in $(properties)
-			|| <toolset>clang in $(properties) )
+	if <toolset>gcc in $(properties)
 		&& <target-os>linux in $(properties)
 		&& ( <asserts>on in $(properties)
 			|| <asserts>production in $(properties)

include/libtorrent/bt_peer_connection.hpp

@@ -364,6 +364,10 @@ namespace libtorrent {
 
 	private:
 
+#if !defined TORRENT_DISABLE_ENCRYPTION
+		void init_bt_handshake();
+#endif
+
 		enum class state_t : std::uint8_t
 		{
 #if !defined TORRENT_DISABLE_ENCRYPTION
@@ -374,7 +378,6 @@ namespace libtorrent {
 			read_pe_cryptofield,
 			read_pe_pad,
 			read_pe_ia,
-			init_bt_handshake,
 #endif
 			read_protocol_identifier,
 			read_info_hash,

include/libtorrent/pe_crypto.hpp

@@ -74,7 +74,6 @@ namespace libtorrent {
 	{
 	public:
 		dh_key_exchange();
-		bool good() const { return true; }
 
 		// Get local public key
 		key_t const& get_local_key() const { return m_dh_local_key; }

src/bt_peer_connection.cpp

@@ -527,7 +527,7 @@ namespace {
 #endif
 
 		m_dh_key_exchange.reset(new (std::nothrow) dh_key_exchange);
-		if (!m_dh_key_exchange || !m_dh_key_exchange->good())
+		if (!m_dh_key_exchange)
 		{
 			disconnect(errors::no_memory, operation_t::encryption);
 			return;
@@ -2729,6 +2729,44 @@ namespace {
 			on_receive_impl(bytes_transferred);
 	}
 
+#if !defined TORRENT_DISABLE_ENCRYPTION
+	void bt_peer_connection::init_bt_handshake()
+	{
+		m_encrypted = true;
+		if (m_rc4_encrypted)
+		{
+			switch_send_crypto(m_rc4);
+			switch_recv_crypto(m_rc4);
+		}
+
+		// decrypt remaining received bytes
+		if (m_rc4_encrypted)
+		{
+			span<char> const remaining = m_recv_buffer.mutable_buffer()
+				.subspan(m_recv_buffer.packet_size());
+			rc4_decrypt(remaining);
+
+#ifndef TORRENT_DISABLE_LOGGING
+			peer_log(peer_log_alert::info, "ENCRYPTION"
+				, "decrypted remaining %d bytes", int(remaining.size()));
+#endif
+		}
+		m_rc4.reset();
+
+		// encrypted portion of handshake completed, toggle
+		// peer_info pe_support flag back to true
+		if (is_outgoing() &&
+			m_settings.get_int(settings_pack::out_enc_policy)
+				== settings_pack::pe_enabled)
+		{
+			torrent_peer* pi = peer_info_struct();
+			TORRENT_ASSERT(pi);
+
+			pi->pe_support = true;
+		}
+	}
+#endif
+
 	void bt_peer_connection::on_receive_impl(std::size_t bytes_transferred)
 	{
 		std::shared_ptr<torrent> t = associated_torrent().lock();
@@ -3119,30 +3157,28 @@ namespace {
 					m_rc4_encrypted = true;
 			}
 
-			int const len_pad = aux::read_int16(recv_buffer);
+			int len_pad = aux::read_int16(recv_buffer);
 			if (len_pad < 0 || len_pad > 512)
 			{
 				disconnect(errors::invalid_pad_size, operation_t::encryption, peer_error);
 				return;
 			}
 
-			m_state = state_t::read_pe_pad;
+			// len(IA) at the end of pad
 			if (!is_outgoing())
-				m_recv_buffer.reset(len_pad + 2); // len(IA) at the end of pad
+				len_pad += 2;
+
+			if (len_pad > 0)
+			{
+				m_state = state_t::read_pe_pad;
+				m_recv_buffer.reset(len_pad);
+			}
 			else
 			{
-				if (len_pad == 0)
-				{
-					m_encrypted = true;
-					if (m_rc4_encrypted)
-					{
-						switch_send_crypto(m_rc4);
-						switch_recv_crypto(m_rc4);
-					}
-					m_state = state_t::init_bt_handshake;
-				}
-				else
-					m_recv_buffer.reset(len_pad);
+				TORRENT_ASSERT(len_pad == 0);
+				init_bt_handshake();
+				m_state = state_t::read_protocol_identifier;
+				m_recv_buffer.reset(20);
 			}
 		}
 
@@ -3164,55 +3200,51 @@ namespace {
 				recv_buffer = recv_buffer.subspan(pad_size);
 				int const len_ia = aux::read_int16(recv_buffer);
 
-				if (len_ia < 0)
+#ifndef TORRENT_DISABLE_LOGGING
+				peer_log(peer_log_alert::info, "ENCRYPTION", "len(IA) : %d", len_ia);
+#endif
+				if (len_ia < 0 || len_ia > 68)
 				{
 					disconnect(errors::invalid_encrypt_handshake, operation_t::encryption, peer_error);
 					return;
 				}
 
-#ifndef TORRENT_DISABLE_LOGGING
-				peer_log(peer_log_alert::info, "ENCRYPTION", "len(IA) : %d", len_ia);
-#endif
 				if (len_ia == 0)
 				{
-					// everything after this is Encrypt2
-					m_encrypted = true;
-					if (m_rc4_encrypted)
-					{
-						switch_send_crypto(m_rc4);
-						switch_recv_crypto(m_rc4);
-					}
-					m_state = state_t::init_bt_handshake;
+					// everything after this is encrypted
+					init_bt_handshake();
+					m_state = state_t::read_protocol_identifier;
+					m_recv_buffer.reset(20);
 				}
 				else
 				{
+					// The other peer indicated that a non-zero bytes will be
+					// encrypted at the start of the underlying bittorrent
+					// protocol. This number of bytes, len_ia, is not
+					// necessarily aligned to message boundaries. We first read
+					// that many bytes, decrypt it, and then pass it back into
+					// the regular protocol parser
 					m_state = state_t::read_pe_ia;
 					m_recv_buffer.reset(len_ia);
 				}
 			}
 			else // is_outgoing()
 			{
-				// everything that arrives after this is Encrypt2
-				m_encrypted = true;
-				if (m_rc4_encrypted)
-				{
-					switch_send_crypto(m_rc4);
-					switch_recv_crypto(m_rc4);
-				}
-				m_state = state_t::init_bt_handshake;
+				// everything that arrives after this is encrypted
+				init_bt_handshake();
+				m_state = state_t::read_protocol_identifier;
+				m_recv_buffer.reset(20);
 			}
 		}
 
 		if (m_state == state_t::read_pe_ia)
 		{
-			received_bytes(0, int(bytes_transferred));
-			bytes_transferred = 0;
 			TORRENT_ASSERT(!is_outgoing());
 			TORRENT_ASSERT(!m_encrypted);
 
 			if (!m_recv_buffer.packet_finished()) return;
 
-			// ia is always rc4, so decrypt it
+			// the IA bytes are always rc4, so decrypt it
 			rc4_decrypt(m_recv_buffer.mutable_buffer().first(m_recv_buffer.packet_size()));
 
 #ifndef TORRENT_DISABLE_LOGGING
@@ -3229,47 +3261,14 @@ namespace {
 			}
 			m_rc4.reset();
 
+			// now that we have decrypted IA length of bytes, we
+			// reinterpret the receive buffer as the very start of a normal
+			// connection. First we expect to find the protocol identifier
+			// (i.e. "BitTorrent Protocol")
 			m_state = state_t::read_protocol_identifier;
 			m_recv_buffer.cut(0, 20);
 		}
 
-		if (m_state == state_t::init_bt_handshake)
-		{
-			received_bytes(0, int(bytes_transferred));
-			bytes_transferred = 0;
-			TORRENT_ASSERT(m_encrypted);
-
-			// decrypt remaining received bytes
-			if (m_rc4_encrypted)
-			{
-				span<char> const remaining = m_recv_buffer.mutable_buffer()
-					.subspan(m_recv_buffer.packet_size());
-				rc4_decrypt(remaining);
-
-#ifndef TORRENT_DISABLE_LOGGING
-				peer_log(peer_log_alert::info, "ENCRYPTION"
-					, "decrypted remaining %d bytes", int(remaining.size()));
-#endif
-			}
-			m_rc4.reset();
-
-			// payload stream, start with 20 handshake bytes
-			m_state = state_t::read_protocol_identifier;
-			m_recv_buffer.reset(20);
-
-			// encrypted portion of handshake completed, toggle
-			// peer_info pe_support flag back to true
-			if (is_outgoing() &&
-				m_settings.get_int(settings_pack::out_enc_policy)
-					== settings_pack::pe_enabled)
-			{
-				torrent_peer* pi = peer_info_struct();
-				TORRENT_ASSERT(pi);
-
-				pi->pe_support = true;
-			}
-		}
-
 #endif // #if !defined TORRENT_DISABLE_ENCRYPTION
 
 		if (m_state == state_t::read_protocol_identifier)
@@ -3327,6 +3326,10 @@ namespace {
 				peer_log(peer_log_alert::info, "ENCRYPTION", "attempting encrypted connection");
 #endif
 				m_state = state_t::read_pe_dhkey;
+				// we're "cutting" off 0 bytes from the receive buffer here
+				// because we want to interpret it as something else. It didn't
+				// contain the expected bittorrent handshake string, so let's
+				// try again to interpret it as an encrypted handshake
 				m_recv_buffer.cut(0, dh_key_len);
 				TORRENT_ASSERT(!m_recv_buffer.packet_finished());
 				return;