Netif (Windows): correct default route detection (v2)

src/common/netif/netif.c

@@ -3,7 +3,8 @@
 #ifndef _WIN32
     #include <net/if.h>
 #else
-    #define IF_NAMESIZE 0
+    #include <ws2tcpip.h>
+    #include <iphlpapi.h>
 #endif
 
 bool ffNetifGetDefaultRouteImpl(char iface[IF_NAMESIZE + 1], uint32_t* ifIndex);

src/common/netif/netif.h

@@ -2,8 +2,5 @@
 
 #include "fastfetch.h"
 
-#ifndef _WIN32
 const char* ffNetifGetDefaultRouteIfName();
-#endif
-
 uint32_t ffNetifGetDefaultRouteIfIndex();

src/common/netif/netif_windows.c

@@ -4,31 +4,51 @@
 #include <ws2tcpip.h> // AF_INET6, IN6_IS_ADDR_UNSPECIFIED
 #include <iphlpapi.h>
 
-bool ffNetifGetDefaultRouteImpl(FF_MAYBE_UNUSED char iface[IF_NAMESIZE + 1], uint32_t* ifIndex)
+bool ffNetifGetDefaultRouteImpl(char iface[IF_NAMESIZE + 1], uint32_t* ifIndex)
 {
     PMIB_IPFORWARD_TABLE2 pIpForwardTable = NULL;
-    DWORD result = GetIpForwardTable2(AF_UNSPEC, &pIpForwardTable);
 
-    if (result != NO_ERROR)
+    if (!NETIO_SUCCESS(GetIpForwardTable2(AF_UNSPEC, &pIpForwardTable)))
         return false;
 
     bool foundDefault = false;
+    uint32_t smallestMetric = UINT32_MAX;
 
     for (ULONG i = 0; i < pIpForwardTable->NumEntries; ++i)
     {
         MIB_IPFORWARD_ROW2* row = &pIpForwardTable->Table[i];
 
-        if (row->Age > row->ValidLifetime) continue;
-
         if ((row->DestinationPrefix.PrefixLength == 0) &&
             ((row->DestinationPrefix.Prefix.Ipv4.sin_family == AF_INET &&
               row->DestinationPrefix.Prefix.Ipv4.sin_addr.S_un.S_addr == 0) ||
              (row->DestinationPrefix.Prefix.Ipv6.sin6_family == AF_INET6 &&
               IN6_IS_ADDR_UNSPECIFIED(&row->DestinationPrefix.Prefix.Ipv6.sin6_addr))))
         {
-            *ifIndex = row->InterfaceIndex;
-            foundDefault = true;
-            break;
+            MIB_IF_ROW2 ifRow = {
+                .InterfaceIndex = row->InterfaceIndex,
+            };
+            if (NETIO_SUCCESS(GetIfEntry2(&ifRow)) &&
+                ifRow.OperStatus == IfOperStatusUp)
+            {
+                MIB_IPINTERFACE_ROW ipInterfaceRow = {
+                    .Family = (row->DestinationPrefix.Prefix.Ipv4.sin_family == AF_INET) ? AF_INET : AF_INET6,
+                    .InterfaceIndex = row->InterfaceIndex,
+                };
+
+                uint32_t realMetric = row->Metric /* Metric offset */;
+
+                if (NETIO_SUCCESS(GetIpInterfaceEntry(&ipInterfaceRow)))
+                    realMetric += ipInterfaceRow.Metric /* Interface metric */;
+
+                if (realMetric < smallestMetric)
+                {
+                    smallestMetric = realMetric;
+                    *ifIndex = row->InterfaceIndex;
+                    if (WideCharToMultiByte(CP_UTF8, 0, ifRow.Alias, -1, iface, IF_NAMESIZE, NULL, NULL) > 0)
+                        iface[IF_NAMESIZE] = '\0';
+                    foundDefault = true;
+                }
+            }
         }
     }