Hi,

On Thu, May 18, 2023 at 12:25 PM Lev Stipakov <lstipa...@gmail.com> wrote:

> From: Lev Stipakov <l...@openvpn.net>
>
> At the moment if --name is not specified, adapter names
> are generated by Windows and they look a bit confusing
> like "Local Area Connection 2".
>
> This is also behavior of "Add a new <driver-name> virtual network
> adapter" shortcuts.
>
> This makes tapctl generate driver-specific names for adapters
> if --name is missing, inclusing resolving duplicates. For instance
> following commands:
>
>   tapctl.exe create --hwid ovpn-dco
>
> will create an adapter named
>
>   OpenVPN Data Channel Offload
>
> If the name is taken, the next one will be
>
>   OpenVPN Data Channel Offload #1
>
> and so on up to 100.
>
> Fixes https://github.com/OpenVPN/openvpn/issues/337


Looks good but some comments below -- mostly nitpicks.


>
> Change-Id: Ic5afb470d14ac7b231d91f0f5de0a0046043a7e0
> Signed-off-by: Lev Stipakov <l...@openvpn.net>
> ---
>  src/tapctl/main.c | 133 +++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 107 insertions(+), 26 deletions(-)
>
> diff --git a/src/tapctl/main.c b/src/tapctl/main.c
> index 1194036f..e4d44794 100644
> --- a/src/tapctl/main.c
> +++ b/src/tapctl/main.c
> @@ -126,6 +126,90 @@ usage(void)
>                title_string);
>  }
>
> +/**
> + * Checks if adapter with given name doesn't already exist
> + */
> +BOOL
>

I would make this static


> +is_adapter_name_available(LPCTSTR name, struct tap_adapter_node
> *adapter_list, BOOL log)
> +{
> +    for (struct tap_adapter_node *a = adapter_list; a; a = a->pNext)
> +    {
> +        if (_tcsicmp(name, a->szName) == 0)
> +        {
> +            if (log)
> +            {
> +                LPOLESTR adapter_id = NULL;
> +                StringFromIID((REFIID)&a->guid, &adapter_id);
> +                _ftprintf(stderr, TEXT("Adapter \"%") TEXT(PRIsLPTSTR)
> TEXT("\" already exists (GUID %")
> +                          TEXT(PRIsLPOLESTR) TEXT(").\n"), a->szName,
> adapter_id);
> +                CoTaskMemFree(adapter_id);
> +            }
> +
> +            return FALSE;
> +        }
> +    }
> +
> +    return TRUE;
> +}
> +
> +/**
> + * Returns unique adapter name based on hwid or NULL if name cannot be
> generated.
> + * Caller is responsible for freeing it.
> + */
> +LPTSTR
>

same static here too?


> +get_unique_adapter_name(LPCTSTR hwid, struct tap_adapter_node
> *adapter_list)
> +{
> +    if (hwid == NULL)
> +    {
> +        return NULL;
> +    }
> +
> +    LPCTSTR base_name;
> +    if (_tcsicmp(hwid, TEXT("ovpn-dco")) == 0)
> +    {
> +        base_name = TEXT("OpenVPN Data Channel Offload");
> +    }
> +    else if (_tcsicmp(hwid, TEXT("wintun")) == 0)
> +    {
> +        base_name = TEXT("OpenVPN Wintun");
> +    }
> +    else if (_tcsicmp(hwid, TEXT("root\\") TEXT(TAP_WIN_COMPONENT_ID)) ==
> 0)
> +    {
> +        base_name = TEXT("OpenVPN TAP-Windows6");
> +    }
> +    else
> +    {
> +        return NULL;
> +    }
> +
> +    if (is_adapter_name_available(base_name, adapter_list, FALSE))
> +    {
> +        return _tcsdup(base_name);
> +    }
> +
> +    TCHAR itot_buf[10];
> +    size_t name_len = (_tcslen(base_name) + sizeof(itot_buf) /
> sizeof(TCHAR) + 2);
>

_countof(itot_buf)  is what we normally use when SIZE() is not available.
That said, do we need itot_buf[] at all? see below.


> +    LPTSTR name = malloc(name_len * sizeof(TCHAR));
> +    if (name == NULL)
> +    {
> +        return NULL;
> +    }
> +    for (int i = 1; i < 100; ++i)
> +    {
> +        *name = TEXT('\0');
> +        _tcscat_s(name, name_len, base_name);
> +        _tcscat_s(name, name_len, TEXT(" #"));
> +        _itot_s(i, itot_buf, sizeof(itot_buf) / sizeof(TCHAR), 10);
> +        _tcscat_s(name, name_len, itot_buf);
>

It looks much simpler to write the above 5 lines as

_stprintf_s(name, name_len, TEXT("%ls #%d"), base_name, i)

Well, the format string should be TEXT("%") TEXT(PRIsLPTSTR) TEXT(" #%d"),
but we are not going to build this ever without UNICODE.

+
> +        if (is_adapter_name_available(name, adapter_list, FALSE))
> +        {
> +            return name;
> +        }
> +    }
> +
> +    return NULL;
> +}
>
>  /**
>   * Program entry point
> @@ -210,50 +294,47 @@ _tmain(int argc, LPCTSTR argv[])
>              iResult = 1; goto quit;
>          }
>
> -        if (szName)
> +        /* Get existing network adapters. */
> +        struct tap_adapter_node *pAdapterList = NULL;
> +        dwResult = tap_list_adapters(NULL, NULL, &pAdapterList);
> +        if (dwResult != ERROR_SUCCESS)
>          {
> -            /* Get existing network adapters. */
> -            struct tap_adapter_node *pAdapterList = NULL;
> -            dwResult = tap_list_adapters(NULL, NULL, &pAdapterList);
> -            if (dwResult != ERROR_SUCCESS)
> -            {
> -                _ftprintf(stderr, TEXT("Enumerating adapters failed
> (error 0x%x).\n"), dwResult);
> -                iResult = 1; goto create_delete_adapter;
> -            }
> +            _ftprintf(stderr, TEXT("Enumerating adapters failed (error
> 0x%x).\n"), dwResult);
> +            iResult = 1; goto create_delete_adapter;
>

Add a line-break to avoid multiple statements per line? I know it's as in
the original, but we can "fix" at least the contexts that are touched..


> +        }
>
> -            /* Check for duplicates. */
> -            for (struct tap_adapter_node *pAdapter = pAdapterList;
> pAdapter; pAdapter = pAdapter->pNext)
> +        LPTSTR adapter_name = szName ? _tcsdup(szName) :
> get_unique_adapter_name(szHwId, pAdapterList);
> +        if (adapter_name)
> +        {
> +            /* Check for duplicates when name was specified,
> +             * otherwise get_adapter_default_name() takes care of it */
> +            if (szName && !is_adapter_name_available(adapter_name,
> pAdapterList, TRUE))
>              {
> -                if (_tcsicmp(szName, pAdapter->szName) == 0)
> -                {
> -                    StringFromIID((REFIID)&pAdapter->guid, &szAdapterId);
> -                    _ftprintf(stderr, TEXT("Adapter \"%")
> TEXT(PRIsLPTSTR) TEXT("\" already exists (GUID %")
> -                              TEXT(PRIsLPOLESTR) TEXT(").\n"),
> pAdapter->szName, szAdapterId);
> -                    CoTaskMemFree(szAdapterId);
> -                    iResult = 1; goto create_cleanup_pAdapterList;
> -                }
> +                iResult = 1; goto create_cleanup_pAdapterList;
>

same here..


>              }
>
>              /* Rename the adapter. */
> -            dwResult = tap_set_adapter_name(&guidAdapter, szName, FALSE);
> +            dwResult = tap_set_adapter_name(&guidAdapter, adapter_name,
> FALSE);
>              if (dwResult != ERROR_SUCCESS)
>              {
>                  StringFromIID((REFIID)&guidAdapter, &szAdapterId);
>                  _ftprintf(stderr, TEXT("Renaming TUN/TAP adapter %")
> TEXT(PRIsLPOLESTR)
>                            TEXT(" to \"%") TEXT(PRIsLPTSTR) TEXT("\"
> failed (error 0x%x).\n"),
> -                          szAdapterId, szName, dwResult);
> +                          szAdapterId, adapter_name, dwResult);
>                  CoTaskMemFree(szAdapterId);
>                  iResult = 1; goto quit;
>

..


>              }
>
>              iResult = 0;
> +        }
>

If (adapter_name) is false, we reach here with iResult not set, but it gets
referenced below. Add an else { iResult = 1; } or initialize iResult to 1
at top?


>  create_cleanup_pAdapterList:
> -            tap_free_adapter_list(pAdapterList);
> -            if (iResult)
> -            {
> -                goto create_delete_adapter;
> -            }
> +        free(adapter_name);
> +
> +        tap_free_adapter_list(pAdapterList);
> +        if (iResult)
> +        {
> +            goto create_delete_adapter;
>          }
>
>          /* Output adapter GUID. */


Selva
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