Introduce function to determine if ZT comms channel to peer is relayed

3rdParty/libzt/CMakeLists.txt

@@ -5,7 +5,7 @@ set(BUILD_HOST_SELFTEST OFF)
 include(FetchContent)
 FetchContent_Declare(libzt
   GIT_REPOSITORY https://github.com/diasurgical/libzt.git
-  GIT_TAG d6c6a069a5041a3e89594c447ced3f15d77618b8)
+  GIT_TAG def49803307920da0ab5b9e9b70b399fdc2943dc)
 FetchContent_MakeAvailableExcludeFromAll(libzt)
 
 if(NOT ANDROID)

Source/dvlnet/protocol_zt.cpp

@@ -12,6 +12,7 @@
 
 #include <lwip/igmp.h>
 #include <lwip/mld6.h>
+#include <lwip/nd6.h>
 #include <lwip/sockets.h>
 #include <lwip/tcpip.h>
 
@@ -312,6 +313,27 @@ bool protocol_zt::is_peer_connected(endpoint &peer)
 	return peer_list.count(peer) != 0 && peer_list[peer].fd != -1;
 }
 
+bool protocol_zt::is_peer_relayed(const endpoint &peer) const
+{
+	ip6_addr_t address = {};
+	IP6_ADDR_PART(&address, 0, peer.addr[0], peer.addr[1], peer.addr[2], peer.addr[3]);
+	IP6_ADDR_PART(&address, 1, peer.addr[4], peer.addr[5], peer.addr[6], peer.addr[7]);
+	IP6_ADDR_PART(&address, 2, peer.addr[8], peer.addr[9], peer.addr[10], peer.addr[11]);
+	IP6_ADDR_PART(&address, 3, peer.addr[12], peer.addr[13], peer.addr[14], peer.addr[15]);
+
+	const u8_t *hwaddr;
+	if (nd6_get_next_hop_addr_or_queue(netif_default, nullptr, &address, &hwaddr) != ERR_OK)
+		return true;
+
+	uint64_t mac = hwaddr[0];
+	mac = (mac << 8) | hwaddr[1];
+	mac = (mac << 8) | hwaddr[2];
+	mac = (mac << 8) | hwaddr[3];
+	mac = (mac << 8) | hwaddr[4];
+	mac = (mac << 8) | hwaddr[5];
+	return zerotier_is_relayed(mac);
+}
+
 std::string protocol_zt::make_default_gamename()
 {
 	std::string ret;

Source/dvlnet/protocol_zt.h

@@ -75,6 +75,7 @@ public:
 	bool get_disconnected(endpoint &peer);
 	bool network_online();
 	bool is_peer_connected(endpoint &peer);
+	bool is_peer_relayed(const endpoint &peer) const;
 	static std::string make_default_gamename();
 
 private:

Source/dvlnet/zerotier_native.cpp

@@ -2,6 +2,7 @@
 
 #include <SDL.h>
 #include <atomic>
+#include <unordered_map>
 
 #ifdef USE_SDL1
 #include "utils/sdl2_to_1_2_backports.h"
@@ -38,6 +39,15 @@ namespace net {
 
 namespace {
 
+// static constexpr uint64_t zt_earth = 0x8056c2e21c000001;
+constexpr uint64_t ZtNetwork = 0xa84ac5c10a7ebb5f;
+
+std::atomic_bool zt_network_ready(false);
+std::atomic_bool zt_node_online(false);
+std::atomic_bool zt_joined(false);
+
+std::unordered_map<uint64_t, zts_event_t> ztPeerEvents;
+
 #ifdef DVL_ZT_SYMLINK
 bool HasMultiByteChars(string_view path)
 {
@@ -107,38 +117,48 @@ std::string ToZTCompliantPath(string_view configPath)
 }
 #endif
 
-} // namespace
-
-// static constexpr uint64_t zt_earth = 0x8056c2e21c000001;
-static constexpr uint64_t ZtNetwork = 0xa84ac5c10a7ebb5f;
-
-static std::atomic_bool zt_network_ready(false);
-static std::atomic_bool zt_node_online(false);
-static std::atomic_bool zt_joined(false);
-
-static void Callback(void *ptr)
+void Callback(void *ptr)
 {
 	zts_event_msg_t *msg = reinterpret_cast<zts_event_msg_t *>(ptr);
-	// printf("callback %i\n", msg->eventCode);
-	if (msg->event_code == ZTS_EVENT_NODE_ONLINE) {
+
+	switch (msg->event_code) {
+	case ZTS_EVENT_NODE_ONLINE:
 		Log("ZeroTier: ZTS_EVENT_NODE_ONLINE, nodeId={:x}", (unsigned long long)msg->node->node_id);
 		zt_node_online = true;
 		if (!zt_joined) {
 			zts_net_join(ZtNetwork);
 			zt_joined = true;
 		}
-	} else if (msg->event_code == ZTS_EVENT_NODE_OFFLINE) {
+		break;
+
+	case ZTS_EVENT_NODE_OFFLINE:
 		Log("ZeroTier: ZTS_EVENT_NODE_OFFLINE");
 		zt_node_online = false;
-	} else if (msg->event_code == ZTS_EVENT_NETWORK_READY_IP6) {
+		break;
+
+	case ZTS_EVENT_NETWORK_READY_IP6:
 		Log("ZeroTier: ZTS_EVENT_NETWORK_READY_IP6, networkId={:x}", (unsigned long long)msg->network->net_id);
 		zt_ip6setup();
 		zt_network_ready = true;
-	} else if (msg->event_code == ZTS_EVENT_ADDR_ADDED_IP6) {
+		break;
+
+	case ZTS_EVENT_ADDR_ADDED_IP6:
 		print_ip6_addr(&(msg->addr->addr));
+		break;
+
+	case ZTS_EVENT_PEER_DIRECT:
+	case ZTS_EVENT_PEER_RELAY:
+		ztPeerEvents[msg->peer->peer_id] = static_cast<zts_event_t>(msg->event_code);
+		break;
+
+	case ZTS_EVENT_PEER_PATH_DEAD:
+		ztPeerEvents.erase(msg->peer->peer_id);
+		break;
 	}
 }
 
+} // namespace
+
 bool zerotier_network_ready()
 {
 	return zt_network_ready && zt_node_online;
@@ -156,5 +176,20 @@ void zerotier_network_start()
 	zts_node_start();
 }
 
+bool zerotier_is_relayed(uint64_t mac)
+{
+	bool isRelayed = true;
+	if (zts_core_lock_obtain() != ZTS_ERR_OK)
+		return isRelayed;
+	zts_peer_info_t peerInfo;
+	if (zts_core_query_peer_info(ZtNetwork, mac, &peerInfo) == ZTS_ERR_OK) {
+		auto peerEvent = ztPeerEvents.find(peerInfo.peer_id);
+		if (peerEvent != ztPeerEvents.end())
+			isRelayed = (peerEvent->second == ZTS_EVENT_PEER_RELAY);
+	}
+	zts_core_lock_release();
+	return isRelayed;
+}
+
 } // namespace net
 } // namespace devilution

Source/dvlnet/zerotier_native.h

@@ -1,11 +1,13 @@
 #pragma once
 
+#include <cstdint>
+
 namespace devilution {
 namespace net {
 
 bool zerotier_network_ready();
 void zerotier_network_start();
-void zerotier_network_stop();
+bool zerotier_is_relayed(uint64_t mac);
 
 // NOTE: We have patched our libzt to have the corresponding multicast
 // MAC hardcoded, since libzt is still missing the proper handling.