qga: replace GetIfEntry with GetIfEntry2 for interface stats

The data obtained by GetIfEntry is 32 bits, and it may overflow. Thus
using GetIfEntry2 instead of GetIfEntry.
Signed-off-by: NZhiPeng Lu <lu.zhipeng@zte.com.cn>
*avoid CamelCase variable names
*update field names for MIB_IFROW -> MIB_IF_ROW2
*dynamically probe for GetIfIndex2 to deal with older OSs
*check return value from get_interface_index
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

qga/commands-win32.c

@@ -1169,24 +1169,46 @@ static DWORD get_interface_index(const char *guid)
         return index;
     }
 }
+
+typedef NETIOAPI_API (WINAPI *GetIfEntry2Func)(PMIB_IF_ROW2 Row);
+
 static int guest_get_network_stats(const char *name,
-                       GuestNetworkInterfaceStat *stats)
+                                   GuestNetworkInterfaceStat *stats)
 {
-    DWORD if_index = 0;
-    MIB_IFROW a_mid_ifrow;
-    memset(&a_mid_ifrow, 0, sizeof(a_mid_ifrow));
-    if_index = get_interface_index(name);
-    a_mid_ifrow.dwIndex = if_index;
-    if (NO_ERROR == GetIfEntry(&a_mid_ifrow)) {
-        stats->rx_bytes = a_mid_ifrow.dwInOctets;
-        stats->rx_packets = a_mid_ifrow.dwInUcastPkts;
-        stats->rx_errs = a_mid_ifrow.dwInErrors;
-        stats->rx_dropped = a_mid_ifrow.dwInDiscards;
-        stats->tx_bytes = a_mid_ifrow.dwOutOctets;
-        stats->tx_packets = a_mid_ifrow.dwOutUcastPkts;
-        stats->tx_errs = a_mid_ifrow.dwOutErrors;
-        stats->tx_dropped = a_mid_ifrow.dwOutDiscards;
-        return 0;
+    OSVERSIONINFO os_ver;
+
+    os_ver.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
+    GetVersionEx(&os_ver);
+    if (os_ver.dwMajorVersion >= 6) {
+        MIB_IF_ROW2 a_mid_ifrow;
+        GetIfEntry2Func getifentry2_ex;
+        DWORD if_index = 0;
+        HMODULE module = GetModuleHandle("iphlpapi");
+        PVOID func = GetProcAddress(module, "GetIfEntry2");
+
+        if (func == NULL) {
+            return -1;
+        }
+
+        getifentry2_ex = (GetIfEntry2Func)func;
+        if_index = get_interface_index(name);
+        if (if_index == (DWORD)~0) {
+            return -1;
+        }
+
+        memset(&a_mid_ifrow, 0, sizeof(a_mid_ifrow));
+        a_mid_ifrow.InterfaceIndex = if_index;
+        if (NO_ERROR == getifentry2_ex(&a_mid_ifrow)) {
+            stats->rx_bytes = a_mid_ifrow.InOctets;
+            stats->rx_packets = a_mid_ifrow.InUcastPkts;
+            stats->rx_errs = a_mid_ifrow.InErrors;
+            stats->rx_dropped = a_mid_ifrow.InDiscards;
+            stats->tx_bytes = a_mid_ifrow.OutOctets;
+            stats->tx_packets = a_mid_ifrow.OutUcastPkts;
+            stats->tx_errs = a_mid_ifrow.OutErrors;
+            stats->tx_dropped = a_mid_ifrow.OutDiscards;
+            return 0;
+        }
     }
     return -1;
 }