ipconfig: Call GetAdaptersAddresses() in a loop.

programs/ipconfig/ipconfig.c

@@ -138,23 +138,32 @@ static BOOL socket_address_to_string(WCHAR *buf, DWORD len, SOCKET_ADDRESS *addr
                                buf, &len) == 0;
 }
 
-static void print_basic_information(void)
+static IP_ADAPTER_ADDRESSES *get_adapters(void)
 {
-    IP_ADAPTER_ADDRESSES *adapters;
-    ULONG out = 0;
+    ULONG err, size = 4096;
+    IP_ADAPTER_ADDRESSES *tmp, *ret;
 
-    if (GetAdaptersAddresses(AF_UNSPEC, GAA_FLAG_INCLUDE_GATEWAYS,
-                             NULL, NULL, &out) == ERROR_BUFFER_OVERFLOW)
+    if (!(ret = malloc( size ))) return NULL;
+    err = GetAdaptersAddresses( AF_UNSPEC, GAA_FLAG_INCLUDE_GATEWAYS, NULL, ret, &size );
+    while (err == ERROR_BUFFER_OVERFLOW)
     {
-        adapters = malloc(out);
+        if (!(tmp = realloc( ret, size ))) break;
+        ret = tmp;
+        err = GetAdaptersAddresses( AF_UNSPEC, GAA_FLAG_INCLUDE_GATEWAYS, NULL, ret, &size );
+    }
+    if (err == ERROR_SUCCESS) return ret;
+    free( ret );
+    return NULL;
+}
+
+static void print_basic_information(void)
+{
+    IP_ADAPTER_ADDRESSES *adapters, *p;
+
+    adapters = get_adapters();
     if (!adapters)
         exit(1);
 
-        if (GetAdaptersAddresses(AF_UNSPEC, GAA_FLAG_INCLUDE_GATEWAYS,
-                                 NULL, adapters, &out) == ERROR_SUCCESS)
-        {
-            IP_ADAPTER_ADDRESSES *p;
-
     for (p = adapters; p; p = p->Next)
     {
         IP_ADAPTER_UNICAST_ADDRESS *addr;
@@ -192,10 +201,7 @@ static void print_basic_information(void)
 
         ipconfig_printfW(L"\n");
     }
-        }
-
     free(adapters);
-    }
 }
 
 static const WCHAR *nodetype_to_string(DWORD type)
@@ -260,8 +266,8 @@ static const WCHAR *boolean_to_string(int value)
 static void print_full_information(void)
 {
     FIXED_INFO *info;
-    IP_ADAPTER_ADDRESSES *adapters;
-    ULONG out = 0;
+    IP_ADAPTER_ADDRESSES *adapters, *p;
+    ULONG out;
 
     if (GetNetworkParams(NULL, &out) == ERROR_BUFFER_OVERFLOW)
     {
@@ -291,24 +297,15 @@ static void print_full_information(void)
         free(info);
     }
 
-    if (GetAdaptersAddresses(AF_UNSPEC, GAA_FLAG_INCLUDE_GATEWAYS,
-                             NULL, NULL, &out) == ERROR_BUFFER_OVERFLOW)
-    {
-        adapters = malloc(out);
+    adapters = get_adapters();
     if (!adapters)
         exit(1);
 
-        if (GetAdaptersAddresses(AF_UNSPEC, GAA_FLAG_INCLUDE_GATEWAYS,
-                                 NULL, adapters, &out) == ERROR_SUCCESS)
-        {
-            IP_ADAPTER_ADDRESSES *p;
-
     for (p = adapters; p; p = p->Next)
     {
         IP_ADAPTER_UNICAST_ADDRESS *addr;
-                WCHAR physaddr_buf[3 * MAX_ADAPTER_ADDRESS_LENGTH];
+        WCHAR physaddr_buf[3 * MAX_ADAPTER_ADDRESS_LENGTH], addr_buf[54];
         IP_ADAPTER_GATEWAY_ADDRESS_LH *gateway;
-                WCHAR addr_buf[54];
 
         ipconfig_message_printfW(STRING_ADAPTER_FRIENDLY, iftype_to_string(p->IfType), p->FriendlyName);
         ipconfig_printfW(L"\n");
@@ -346,10 +343,7 @@ static void print_full_information(void)
 
         ipconfig_printfW(L"\n");
     }
-        }
-
     free(adapters);
-    }
 }
 
 int __cdecl wmain(int argc, WCHAR *argv[])