refactor in crypto_plugin::decrypt to use tuple

include/libtorrent/extensions.hpp

@@ -498,6 +498,9 @@ namespace libtorrent
 		encrypt(span<span<char>> /*send_vec*/) = 0;
 
 		// decrypt the provided buffers.
+		// returns is a tuple representing the values
+		// (consume, produce, packet_size)
+		//
 		// consume is set to the number of bytes which should be trimmed from the
 		// head of the buffers, default is 0
 		//
@@ -506,8 +509,7 @@ namespace libtorrent
 		//
 		// packet_size is set to the minimum number of bytes which must be read to
 		// advance the next step of decryption. default is 0
-		virtual void decrypt(span<span<char>> /*receive_vec*/
-			, int& /* consume */, int& /*produce*/, int& /*packet_size*/) = 0;
+		virtual std::tuple<int, int, int> decrypt(span<span<char>> /*receive_vec*/) = 0;
 	};
 }
 

include/libtorrent/pe_crypto.hpp

@@ -145,10 +145,7 @@ namespace libtorrent
 		std::tuple<int, span<span<char const>>>
 		encrypt(span<span<char>> buf) override;
 
-		void decrypt(span<span<char>> buf
-			, int& consume
-			, int& produce
-			, int& packet_size) override;
+		std::tuple<int, int, int> decrypt(span<span<char>> buf) override;
 
 	private:
 		rc4 m_rc4_incoming;

src/bt_peer_connection.cpp

@@ -727,10 +727,7 @@ namespace libtorrent
 
 	void bt_peer_connection::rc4_decrypt(span<char> buf)
 	{
-		int consume = 0;
-		int produce = int(buf.size());
-		int packet_size = 0;
-		m_rc4->decrypt(buf, consume, produce, packet_size);
+		m_rc4->decrypt(buf);
 	}
 
 	namespace {

src/pe_crypto.cpp

@@ -219,9 +219,9 @@ namespace libtorrent
 		if (recv_buffer.crypto_packet_finished())
 		{
 			span<char> wr_buf = recv_buffer.mutable_buffer(bytes_transferred);
+			int produce = 0;
 			int packet_size = 0;
-			int produce = int(bytes_transferred);
-			m_dec_handler->decrypt(wr_buf, consume, produce, packet_size);
+			std::tie(consume, produce, packet_size) = m_dec_handler->decrypt(wr_buf);
 			TORRENT_ASSERT(packet_size || produce);
 			TORRENT_ASSERT(packet_size >= 0);
 			bytes_transferred = produce;
@@ -265,7 +265,7 @@ namespace libtorrent
 			int consume = 0;
 			int produce = 0;
 			std::vector<span<char>> wr_buf;
-			crypto->decrypt(wr_buf, consume, produce, packet_size);
+			std::tie(consume, produce, packet_size) = crypto->decrypt(wr_buf);
 			TORRENT_ASSERT(wr_buf.empty());
 			TORRENT_ASSERT(consume == 0);
 			TORRENT_ASSERT(produce == 0);
@@ -289,12 +289,9 @@ namespace libtorrent
 		rc4_init(reinterpret_cast<unsigned char const*>(key.data())
 			, key.size(), &m_rc4_incoming);
 		// Discard first 1024 bytes
-		int consume = 0;
-		int produce = 0;
-		int packet_size = 0;
 		char buf[1024];
 		span<char> vec(buf, sizeof(buf));
-		decrypt(vec, consume, produce, packet_size);
+		decrypt(vec);
 	}
 
 	void rc4_handler::set_outgoing_key(span<char const> key)
@@ -330,16 +327,9 @@ namespace libtorrent
 		return std::make_tuple(bytes_processed, empty);
 	}
 
-	void rc4_handler::decrypt(span<span<char>> bufs
-		, int& consume
-		, int& produce
-		, int& packet_size)
+	std::tuple<int, int, int> rc4_handler::decrypt(span<span<char>> bufs)
 	{
-		// these are out-parameters that are not set
-		TORRENT_UNUSED(consume);
-		TORRENT_UNUSED(packet_size);
-
-		if (!m_decrypt) return;
+		if (!m_decrypt) std::make_tuple(0, 0, 0);
 
 		int bytes_processed = 0;
 		for (auto& buf : bufs)
@@ -353,7 +343,7 @@ namespace libtorrent
 			bytes_processed += len;
 			rc4_encrypt(pos, len, &m_rc4_incoming);
 		}
-		produce = bytes_processed;
+		return std::make_tuple(0, bytes_processed, 0);
 	}
 
 // All this code is based on libTomCrypt (http://www.libtomcrypt.com/)

test/test_pe_crypto.cpp

@@ -73,10 +73,10 @@ void test_enc_handler(libtorrent::crypto_plugin& a, libtorrent::crypto_plugin& b
 
 		{
 			int consume = 0;
-			int produce = buf_len;
+			int produce = 0;
 			int packet_size = 0;
 			lt::span<char> iovec(&buf[0], buf_len);
-			b.decrypt(iovec, consume, produce, packet_size);
+			std::tie(consume, produce, packet_size) = b.decrypt(iovec);
 			TEST_CHECK(buf == cmp_buf);
 			TEST_EQUAL(consume, 0);
 			TEST_EQUAL(produce, buf_len);
@@ -93,10 +93,10 @@ void test_enc_handler(libtorrent::crypto_plugin& a, libtorrent::crypto_plugin& b
 			TEST_EQUAL(next_barrier, buf_len);
 
 			int consume = 0;
-			int produce = buf_len;
+			int produce = 0;
 			int packet_size = 0;
 			lt::span<char> iovec2(&buf[0], buf_len);
-			a.decrypt(iovec2, consume, produce, packet_size);
+			std::tie(consume, produce, packet_size) = a.decrypt(iovec2);
 			TEST_CHECK(buf == cmp_buf);
 			TEST_EQUAL(consume, 0);
 			TEST_EQUAL(produce, buf_len);