Codechange: Swap SocketList map key/value around.

This map is used store socket and address together, and, other than
checking that the address does not already have a socket, the data layout
does not seem particularly important.

However, as address is the key, technically it should not be modified,
and address may self-modify itself during comparisons.

src/network/core/address.cpp

@@ -259,7 +259,7 @@ SOCKET NetworkAddress::Resolve(int family, int socktype, int flags, SocketList *
 		 * of course totally unneeded ;) */
 		if (sockets != nullptr) {
 			NetworkAddress address(runp->ai_addr, (int)runp->ai_addrlen);
-			if (sockets->Contains(address)) continue;
+			if (std::any_of(sockets->begin(), sockets->end(), [&address](const auto &p) { return p.second == address; })) continue;
 		}
 		sock = func(runp);
 		if (sock == INVALID_SOCKET) continue;
@@ -284,7 +284,7 @@ SOCKET NetworkAddress::Resolve(int family, int socktype, int flags, SocketList *
 		}
 
 		NetworkAddress addr(runp->ai_addr, (int)runp->ai_addrlen);
-		(*sockets)[addr] = sock;
+		(*sockets)[sock] = addr;
 		sock = INVALID_SOCKET;
 	}
 	freeaddrinfo (ai);

src/network/core/address.h

@@ -19,7 +19,7 @@
 
 class NetworkAddress;
 typedef std::vector<NetworkAddress> NetworkAddressList; ///< Type for a list of addresses.
-typedef SmallMap<NetworkAddress, SOCKET> SocketList;    ///< Type for a mapping between address and socket.
+typedef SmallMap<SOCKET, NetworkAddress> SocketList;    ///< Type for a mapping between address and socket.
 
 /**
  * Wrapper for (un)resolved network addresses; there's no reason to transform

src/network/core/tcp_listen.h

@@ -114,7 +114,7 @@ public:
 
 		/* take care of listener port */
 		for (auto &s : sockets) {
-			FD_SET(s.second, &read_fd);
+			FD_SET(s.first, &read_fd);
 		}
 
 		tv.tv_sec = tv.tv_usec = 0; // don't block at all.
@@ -122,7 +122,7 @@ public:
 
 		/* accept clients.. */
 		for (auto &s : sockets) {
-			if (FD_ISSET(s.second, &read_fd)) AcceptClient(s.second);
+			if (FD_ISSET(s.first, &read_fd)) AcceptClient(s.first);
 		}
 
 		/* read stuff from clients */
@@ -164,7 +164,7 @@ public:
 	static void CloseListeners()
 	{
 		for (auto &s : sockets) {
-			closesocket(s.second);
+			closesocket(s.first);
 		}
 		sockets.clear();
 		Debug(net, 5, "[{}] Closed listeners", Tsocket::GetName());

src/network/core/udp.cpp

@@ -59,7 +59,7 @@ bool NetworkUDPSocketHandler::Listen()
 void NetworkUDPSocketHandler::CloseSocket()
 {
 	for (auto &s : this->sockets) {
-		closesocket(s.second);
+		closesocket(s.first);
 	}
 	this->sockets.clear();
 }
@@ -81,20 +81,20 @@ void NetworkUDPSocketHandler::SendPacket(Packet *p, NetworkAddress *recv, bool a
 		NetworkAddress send(*recv);
 
 		/* Not the same type */
-		if (!send.IsFamily(s.first.GetAddress()->ss_family)) continue;
+		if (!send.IsFamily(s.second.GetAddress()->ss_family)) continue;
 
 		p->PrepareToSend();
 
 		if (broadcast) {
 			/* Enable broadcast */
 			unsigned long val = 1;
-			if (setsockopt(s.second, SOL_SOCKET, SO_BROADCAST, (char *) &val, sizeof(val)) < 0) {
+			if (setsockopt(s.first, SOL_SOCKET, SO_BROADCAST, (char *) &val, sizeof(val)) < 0) {
 				Debug(net, 1, "Setting broadcast mode failed: {}", NetworkError::GetLast().AsString());
 			}
 		}
 
 		/* Send the buffer */
-		ssize_t res = p->TransferOut<int>(sendto, s.second, 0, (const struct sockaddr *)send.GetAddress(), send.GetAddressLength());
+		ssize_t res = p->TransferOut<int>(sendto, s.first, 0, (const struct sockaddr *)send.GetAddress(), send.GetAddressLength());
 		Debug(net, 7, "sendto({})", send.GetAddressAsString());
 
 		/* Check for any errors, but ignore it otherwise */
@@ -119,8 +119,8 @@ void NetworkUDPSocketHandler::ReceivePackets()
 			socklen_t client_len = sizeof(client_addr);
 
 			/* Try to receive anything */
-			SetNonBlocking(s.second); // Some OSes seem to lose the non-blocking status of the socket
+			SetNonBlocking(s.first); // Some OSes seem to lose the non-blocking status of the socket
-			ssize_t nbytes = p.TransferIn<int>(recvfrom, s.second, 0, (struct sockaddr *)&client_addr, &client_len);
+			ssize_t nbytes = p.TransferIn<int>(recvfrom, s.first, 0, (struct sockaddr *)&client_addr, &client_len);
 
 			/* Did we get the bytes for the base header of the packet? */
 			if (nbytes <= 0) break;    // No data, i.e. no packet