[libvirt] [PATCH] remote: Fix TLS transport on Windows

[Matthias Bolte]

2010/11/22 Eric Blake <eblake at redhat.com>:
> On 11/22/2010 01:42 PM, Matthias Bolte wrote:
>>>> This doesn't entirely make any sense to me. GNUTLS also uses GNULIB,
>>>> including all its socket wrappers for send/recv. If the push/pull
>>>> function is NULL, gnulib does this
>>>>
>>>>      if (session->internals._gnutls_push_func == NULL)
>>>>        {
>>>>          i = send (GNUTLS_POINTER_TO_INT (fd), &ptr[n - left], left, 0);
>>>>
>>
>> Okay, yes GnuTLS uses gnulib, but they explicitly don't use gnulib's
>> replacements for send() and recv() on Windows. See
>> lib/gnutls_buffers.c:
>>
>> /* We need to disable gnulib's replacement wrappers to get native
>>    Windows interfaces. */
>> #undef recv
>> #undef send
>>
>> GnuTLS decided to use the native Windows versions of send() and
>> recv(). This cannot be changed, as that would break existing
>> applications using GnuTLS on Windows relying on GnuTLS using the
>> native Windows versions of send() and recv(). Therefore, I think my
>> patch is necessary, as libvirt requires GnuTLS to use gnulib's
>> replacement functions.
>
> Makes sense to me.  However, why the double cast?
>
> +#if HAVE_WINSOCK2_H
> +static ssize_t
> +custom_gnutls_push(void *s, const void *buf, size_t len)
> +{
> +    return send((int)(long)s, buf, len, 0);
> +}
> +
> +static ssize_t
> +custom_gnutls_pull(void *s, void *buf, size_t len)
> +{
> +    return recv((int)(long)s, buf, len, 0);
> +}
> +#endif
>
> Wouldn't send((size_t)s, ...) be better than send((int)(long)s,...)?
>

I just used what'a in curl, as directly casting from void* to int
would give this error on 64bit platform:

  error: cast from pointer to integer of different size [-Wpointer-to-int-cast]

(Yes, this is tested on Linux 64bit, as I didn't setup mingw-w64 yet)

Casting to size_t works too.

Here's a v2 that casts to size_t and has an improved commit message.

Matthias
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