Fix Windows build: tun_windows.c function pointers and MIB_IPINTERFACE_ROW

- Fix function pointer declarations in tun_windows.c (removed broken macro)
- Use explicit GetProcAddress calls for each Wintun function
- Remove invalid fields from MIB_IPINTERFACE_ROW (PromiscuousMode, DadState, etc.)
- Add #ifndef _WIN32 around IF_NAMESIZE/if_indextoname in etcp_connections.c
- All 22 tests pass on Linux

src/etcp_connections.c

@@ -312,12 +312,14 @@ struct ETCP_SOCKET* etcp_socket_add(struct UTUN_INSTANCE* instance, struct socka
     }
     
     // Bind to interface if specified (Linux only)
+#ifndef _WIN32
     if (netif_index > 0) {
         char ifname[IF_NAMESIZE];
         if (if_indextoname(netif_index, ifname)) {
             socket_bind_to_device(e_sock->fd, ifname);
         }
     }
+#endif
     
     // Store the local address and bind socket if provided
     if (ip) {

src/tun_windows.c

@@ -11,7 +11,7 @@
 #include <iphlpapi.h>
 #include <ws2tcpip.h>
 
-// Wintun function pointers
+// Wintun function pointers (using function pointer syntax)
 static HMODULE wintun_dll = NULL;
 static WINTUN_CREATE_ADAPTER_FUNC WintunCreateAdapter = NULL;
 static WINTUN_CLOSE_ADAPTER_FUNC WintunCloseAdapter = NULL;
@@ -69,28 +69,28 @@ static int wintun_load_dll(void) {
     }
 
     // Resolve function pointers
-    #define WINTUN_GET_FUNC(name) \
-        name = (WINTUN_##name##_FUNC)GetProcAddress(wintun_dll, "Wintun" #name); \
-        if (!name) { \
-            DEBUG_ERROR(DEBUG_CATEGORY_TUN, "Failed to resolve Wintun" #name); \
-            FreeLibrary(wintun_dll); \
-            wintun_dll = NULL; \
-            return -1; \
-        }
-
-    WINTUN_GET_FUNC(CreateAdapter);
-    WINTUN_GET_FUNC(CloseAdapter);
-    WINTUN_GET_FUNC(OpenAdapter);
-    WINTUN_GET_FUNC(GetAdapterLUID);
-    WINTUN_GET_FUNC(StartSession);
-    WINTUN_GET_FUNC(EndSession);
-    WINTUN_GET_FUNC(GetReadWaitEvent);
-    WINTUN_GET_FUNC(ReceivePacket);
-    WINTUN_GET_FUNC(ReleaseReceivePacket);
-    WINTUN_GET_FUNC(AllocateSendPacket);
-    WINTUN_GET_FUNC(SendPacket);
-
-    #undef WINTUN_GET_FUNC
+    WintunCreateAdapter = (WINTUN_CREATE_ADAPTER_FUNC)GetProcAddress(wintun_dll, "WintunCreateAdapter");
+    WintunCloseAdapter = (WINTUN_CLOSE_ADAPTER_FUNC)GetProcAddress(wintun_dll, "WintunCloseAdapter");
+    WintunOpenAdapter = (WINTUN_OPEN_ADAPTER_FUNC)GetProcAddress(wintun_dll, "WintunOpenAdapter");
+    WintunGetAdapterLUID = (WINTUN_GET_ADAPTER_LUID_FUNC)GetProcAddress(wintun_dll, "WintunGetAdapterLUID");
+    WintunStartSession = (WINTUN_START_SESSION_FUNC)GetProcAddress(wintun_dll, "WintunStartSession");
+    WintunEndSession = (WINTUN_END_SESSION_FUNC)GetProcAddress(wintun_dll, "WintunEndSession");
+    WintunGetReadWaitEvent = (WINTUN_GET_READ_WAIT_EVENT_FUNC)GetProcAddress(wintun_dll, "WintunGetReadWaitEvent");
+    WintunReceivePacket = (WINTUN_RECEIVE_PACKET_FUNC)GetProcAddress(wintun_dll, "WintunReceivePacket");
+    WintunReleaseReceivePacket = (WINTUN_RELEASE_RECEIVE_PACKET_FUNC)GetProcAddress(wintun_dll, "WintunReleaseReceivePacket");
+    WintunAllocateSendPacket = (WINTUN_ALLOCATE_SEND_PACKET_FUNC)GetProcAddress(wintun_dll, "WintunAllocateSendPacket");
+    WintunSendPacket = (WINTUN_SEND_PACKET_FUNC)GetProcAddress(wintun_dll, "WintunSendPacket");
+
+    // Check that all functions were resolved
+    if (!WintunCreateAdapter || !WintunCloseAdapter || !WintunOpenAdapter ||
+        !WintunGetAdapterLUID || !WintunStartSession || !WintunEndSession ||
+        !WintunGetReadWaitEvent || !WintunReceivePacket || !WintunReleaseReceivePacket ||
+        !WintunAllocateSendPacket || !WintunSendPacket) {
+        DEBUG_ERROR(DEBUG_CATEGORY_TUN, "Failed to resolve some Wintun functions");
+        FreeLibrary(wintun_dll);
+        wintun_dll = NULL;
+        return -1;
+    }
 
     DEBUG_INFO(DEBUG_CATEGORY_TUN, "Wintun.dll loaded successfully");
     return 0;
@@ -142,20 +142,12 @@ static int wintun_set_ip_and_mtu(const NET_LUID* luid, const char* ip_str, int m
         return -1;
     }
 
-    // Set MTU first using MIB_IPINTERFACE_ROW
+    // Set MTU first using MIB_IPINTERFACE_ROW (minimal required fields)
     MIB_IPINTERFACE_ROW row;
     memset(&row, 0, sizeof(row));
     row.Family = AF_INET;
     row.InterfaceLuid = *luid;
-    row.SitePrefixLength = 0;
     row.NlMtu = mtu;
-    row.UseAutomaticMetric = FALSE;
-    row.Metric = 0;
-    row.PromiscuousMode = FALSE;
-    row.DadState = IpDadStatePreferred;
-    row.ConnectionType = NET_IF_CONNECTION_WAKED_UP;
-    row.InterfaceIdentifierPadding = 0;
-    row.SkipAsSource = FALSE;
 
     DWORD ret = SetIpInterfaceEntry(&row);
     if (ret != NO_ERROR && ret != ERROR_OBJECT_ALREADY_EXISTS) {
@@ -168,7 +160,6 @@ static int wintun_set_ip_and_mtu(const NET_LUID* luid, const char* ip_str, int m
     addr_row.InterfaceLuid = *luid;
     addr_row.Address = addr;
     addr_row.OnLinkPrefixLength = 32;  // /32 for point-to-point
-    addr_row.DadState = IpDadStatePreferred;
     addr_row.ValidLifetime = 0xffffffff;
     addr_row.PreferredLifetime = 0xffffffff;