only permit 1 pending session per udp endpoint

llarp/link/server.cpp

@@ -481,10 +481,9 @@ namespace llarp
   bool
   ILinkLayer::PutSession(const std::shared_ptr<ILinkSession>& s)
   {
-    static constexpr size_t MaxSessionsPerEndpoint = 5;
     Lock_t lock(m_PendingMutex);
     const auto address = s->GetRemoteEndpoint();
-    if (m_Pending.count(address) >= MaxSessionsPerEndpoint)
+    if (m_Pending.count(address))
       return false;
     m_Pending.emplace(address, s);
     return true;

llarp/link/server.hpp

@@ -245,7 +245,7 @@ namespace llarp
     SecretKey m_SecretKey;
 
     using AuthedLinks = std::unordered_multimap<RouterID, std::shared_ptr<ILinkSession>>;
-    using Pending = std::unordered_multimap<SockAddr, std::shared_ptr<ILinkSession>>;
+    using Pending = std::unordered_map<SockAddr, std::shared_ptr<ILinkSession>>;
     mutable DECLARE_LOCK(Mutex_t, m_AuthedLinksMutex, ACQUIRED_BEFORE(m_PendingMutex));
     AuthedLinks m_AuthedLinks GUARDED_BY(m_AuthedLinksMutex);
     mutable DECLARE_LOCK(Mutex_t, m_PendingMutex, ACQUIRED_AFTER(m_AuthedLinksMutex));