libtorrent: Add m_tracker_udp_list (#39)

We can't send UDP tracker object references through std:bind() because it copies them, resulting in memory address errors. So we need to store them higher up in the connection manager, where they are always valid.
stickz · Jul 19, 2024 · 80f01db · 80f01db
1 parent 1281df8
commit 80f01db
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Showing 4 changed files with 21 additions and 5 deletions.
diff --git a/libtorrent/src/torrent/connection_manager.cc b/libtorrent/src/torrent/connection_manager.cc
@@ -79,9 +79,9 @@ class UdnsAsyncResolver : public AsyncResolver {
 };
 
 void
-ConnectionManager::start_udp_announce(TrackerUdp *tracker, const sockaddr* sa, int err) {
-  if (tracker != NULL) {
-    tracker->start_announce(sa, err);
+ConnectionManager::start_udp_announce(uint64_t idx, const sockaddr* sa, int err) {
+  if (m_tracker_udp_list[idx] != NULL) {
+    m_tracker_udp_list[idx]->start_announce(sa, err);
   }
 }
 

diff --git a/libtorrent/src/torrent/connection_manager.h b/libtorrent/src/torrent/connection_manager.h
@@ -187,7 +187,10 @@ class LIBTORRENT_EXPORT ConnectionManager {
   void                cancel_async_resolve(void *query);
 
 #ifdef USE_UDNS
-  void                start_udp_announce(TrackerUdp *tracker, const sockaddr* sa, int err);
+  void                start_udp_announce(uint64_t idx, const sockaddr* sa, int err);
+  void                null_udp_tracker(uint64_t idx)          { m_tracker_udp_list[idx] = NULL; }
+  void                add_udp_tracker(TrackerUdp* tracker)    { m_tracker_udp_list.push_back(tracker); }
+  uint64_t            get_udp_tracker_count()                 { return m_tracker_udp_list.size(); }
 #endif
 
   // Legacy synchronous resolver interface.
@@ -227,6 +230,10 @@ class LIBTORRENT_EXPORT ConnectionManager {
   slot_resolver_type  m_slot_resolver;
   slot_throttle_type  m_slot_address_throttle;
 
+#ifdef USE_UDNS
+  std::vector<TrackerUdp*> m_tracker_udp_list;
+#endif
+
   std::unique_ptr<AsyncResolver> m_async_resolver;
 };
 

diff --git a/libtorrent/src/tracker/tracker_udp.cc b/libtorrent/src/tracker/tracker_udp.cc
@@ -77,7 +77,9 @@ TrackerUdp::TrackerUdp(TrackerList* parent, rak::udp_tracker_info& info, int fla
   m_taskTimeout.slot() = std::bind(&TrackerUdp::receive_timeout, this);
 
 #ifdef USE_UDNS
-  m_resolver_callback = std::bind(&ConnectionManager::start_udp_announce, manager->connection_manager(), this, std::placeholders::_1, std::placeholders::_2);
+  manager->connection_manager()->add_udp_tracker(this);
+  m_vec_idx = manager->connection_manager()->get_udp_tracker_count() - 1;
+  m_resolver_callback = std::bind(&ConnectionManager::start_udp_announce, manager->connection_manager(), m_vec_idx, std::placeholders::_1, std::placeholders::_2);
 #else
   m_resolver_callback = std::bind(&TrackerUdp::start_announce, this, std::placeholders::_1, std::placeholders::_2);
 #endif
@@ -86,6 +88,9 @@ TrackerUdp::TrackerUdp(TrackerList* parent, rak::udp_tracker_info& info, int fla
 }
 
 TrackerUdp::~TrackerUdp() {
+#ifdef USE_UDNS
+  manager->connection_manager()->null_udp_tracker(m_vec_idx);
+#endif
   close_directly();
 }
 

diff --git a/libtorrent/src/tracker/tracker_udp.h b/libtorrent/src/tracker/tracker_udp.h
@@ -105,6 +105,10 @@ class TrackerUdp : public SocketDatagram, public Tracker {
   uint32_t            m_action;
   uint64_t            m_connectionId;
   uint32_t            m_transactionId;
+
+#ifdef USE_UDNS
+  uint64_t            m_vec_idx;
+#endif  
 
   ReadBuffer*         m_readBuffer;
   WriteBuffer*        m_writeBuffer;