Merge pull request #1515 from ethereum/p2p

Fix crash accessing nullptr.

libp2p/Host.cpp

@@ -217,9 +217,8 @@ void Host::startPeerSession(Public const& _id, RLP const& _rlp, RLPXFrameIO* _io
 					ps->disconnect(DuplicatePeer);
 					return;
 				}
-		m_sessions[_id] = ps;
-	}
-	ps->start();
+		
+		// todo: mutex Session::m_capabilities and move for(:caps) out of mutex.
 		unsigned o = (unsigned)UserPacket;
 		for (auto const& i: caps)
 			if (haveCapability(i))
@@ -227,6 +226,10 @@ void Host::startPeerSession(Public const& _id, RLP const& _rlp, RLPXFrameIO* _io
 				ps->m_capabilities[i] = shared_ptr<Capability>(m_capabilities[i]->newPeerCapability(ps.get(), o));
 				o += m_capabilities[i]->messageCount();
 			}
+		ps->start();
+		m_sessions[_id] = ps;
+	}
+	
 	clog(NetNote) << "p2p.host.peer.register" << _id.abridged();
 	StructuredLogger::p2pConnected(_id.abridged(), ps->m_peer->peerEndpoint(), ps->m_peer->m_lastConnected, clientVersion, peerCount());
 }

libwhisper/WhisperHost.cpp

@@ -162,7 +162,7 @@ void WhisperHost::uninstallWatch(unsigned _i)
 
 void WhisperHost::doWork()
 {
-	for (auto& i: peerSessions())
+	for (auto i: peerSessions())
 		i.first->cap<WhisperPeer>().get()->sendMessages();
 	cleanup();
 }