From e18366bb6b577df27149b3e87d352130491154a1 Mon Sep 17 00:00:00 2001
From: arvidn <arvid@libtorrent.org>
Date: Sat, 11 Jan 2020 02:01:07 +0100
Subject: [PATCH] make sure &key= stays consistent between different source IPs
 (as mandated by BEP7)

---
 ChangeLog                                |  1 +
 include/libtorrent/aux_/session_impl.hpp |  6 ------
 simulation/test_tracker.cpp              |  4 ++--
 src/session_impl.cpp                     | 27 ------------------------
 4 files changed, 3 insertions(+), 35 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index e1f6a749a..8a8a8adc2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,4 @@
+	* make sure &key= stays consistent between different source IPs (as mandated by BEP7)
 	* fix binding sockets to outgoing interface
 	* add new socks5_alert to trouble shoot SOCKS5 proxies
 
diff --git a/include/libtorrent/aux_/session_impl.hpp b/include/libtorrent/aux_/session_impl.hpp
index e248d695b..5c5dddbbb 100644
--- a/include/libtorrent/aux_/session_impl.hpp
+++ b/include/libtorrent/aux_/session_impl.hpp
@@ -221,10 +221,6 @@ namespace aux {
 
 		std::shared_ptr<natpmp> natpmp_mapper;
 
-		// the key is an id that is used to identify the
-		// client with the tracker only.
-		std::uint32_t tracker_key = 0;
-
 		// set to true when we receive an incoming connection from this listen
 		// socket
 		bool incoming_connection = false;
@@ -630,8 +626,6 @@ namespace aux {
 			// or zero if no matching listen socket is found
 			int listen_port(transport ssl, address const& local_addr) override;
 
-			std::uint32_t get_tracker_key(address const& iface) const;
-
 			void for_each_listen_socket(std::function<void(aux::listen_socket_handle const&)> f) override
 			{
 				for (auto& s : m_listen_sockets)
diff --git a/simulation/test_tracker.cpp b/simulation/test_tracker.cpp
index 517f2b855..ed296c15e 100644
--- a/simulation/test_tracker.cpp
+++ b/simulation/test_tracker.cpp
@@ -1108,8 +1108,8 @@ TORRENT_TEST(tracker_key_argument)
 		, [](torrent_handle h) {}
 		, [](torrent_handle h) {});
 
-	// make sure we got two separate keys, one for each listen socket interface
-	TEST_EQUAL(keys.size(), 2);
+	// make sure we got the same key for all listen socket interface
+	TEST_EQUAL(keys.size(), 1);
 }
 
 // make sure we do _not_ send our IPv6 address to trackers for non-private
diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index 10f757b83..1773a96ff 100644
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -1067,8 +1067,6 @@ namespace aux {
 		{
 			auto ls = req.outgoing_socket.get();
 
-			req.key ^= ls->tracker_key;
-
 			req.listen_port =
 #ifdef TORRENT_USE_OPENSSL
 			// SSL torrents use the SSL listen port
@@ -1092,9 +1090,6 @@ namespace aux {
 #endif
 					listen_port(ls.get());
 
-				// we combine the per-torrent key with the per-interface key to make
-				// them consistent and unique per torrent and interface
-				socket_req.key ^= ls->tracker_key;
 				socket_req.outgoing_socket = ls;
 				m_tracker_manager.queue_request(get_io_service(), std::move(socket_req), c);
 			}
@@ -1315,27 +1310,6 @@ namespace aux {
 			reopen_outgoing_sockets();
 	}
 
-	std::uint32_t session_impl::get_tracker_key(address const& iface) const
-	{
-		auto const ses = reinterpret_cast<uintptr_t>(this);
-		hasher h(reinterpret_cast<char const*>(&ses), sizeof(ses));
-		if (iface.is_v4())
-		{
-			auto const b = iface.to_v4().to_bytes();
-			h.update({reinterpret_cast<char const*>(b.data())
-				, std::ptrdiff_t(b.size())});
-		}
-		else
-		{
-			auto const b = iface.to_v6().to_bytes();
-			h.update({reinterpret_cast<char const*>(b.data())
-				, std::ptrdiff_t(b.size())});
-		}
-		sha1_hash const hash = h.final();
-		unsigned char const* ptr = &hash[0];
-		return detail::read_uint32(ptr);
-	}
-
 	std::shared_ptr<listen_socket_t> session_impl::setup_listener(
 		listen_endpoint_t const& lep, error_code& ec)
 	{
@@ -1653,7 +1627,6 @@ namespace aux {
 			ret->local_endpoint = tcp::endpoint(udp_ep.address(), udp_ep.port());
 		}
 
-		ret->tracker_key = get_tracker_key(ret->local_endpoint.address());
 		ret->device = lep.device;
 
 		error_code err;