[vlc-devel] [PATCH 2/2] Add Apple AirTunes access output plugin

[Michael Hanselmann]

2008/12/2 Rémi Denis-Courmont <rdenis at simphalempin.com>:
> On Tue,  2 Dec 2008 01:06:01 +0100, Michael Hanselmann <public at hansmi.ch>
> wrote:
>> VLC uses libgcrypt for encryption. Unfortunately, libgcrypt doesn't
>> support the OAEP standard as defined in RFC2437 and AirTunes demands
>> OAEP padding for RSA encrypted data. OAEP has been reimplemented from
>> scratch based on the specification for this plugin. Maybe these
>> functions, MGF1 and AddOaepPadding, could be moved to libvlc at a
>> later point.
>
> To gcrypt rather than to libvlc.

True, but that'll involve more work. I was already looking into it,
but since it'll take a while for users/packagers to upgrade the
library, we'll have to carry around VLC's version for a while anyway.
I changed the patch description to say "These functions, MGF1 and
AddOaepPadding, can be adopted for libgcrypt at a later time." and
will resend it for Christophe's comments.

> (...)
>> +    i_gcrypt_err = gcry_md_open( &md_handle, Hash, 0 );
>> +    if ( CheckForGcryptError( p_access, i_gcrypt_err ) )
>> +    {
>> +        i_err = VLC_EGENERIC;
>> +        goto error;
>> +    }
>
> You should not call gcry_md_close() if gcry_md_open() failed, I believe.
> (...)
>> +error:
>> +    gcry_md_close( md_handle );
>         ^^^^

gcry_md_hd_t is a typedef for a pointer. It doesn't hurt to call
gcry_md_close as md_handle will be NULL (also see below).

>> +error:
>> +    gcry_sexp_release( sexp_rsa_params );
>> +    gcry_sexp_release( sexp_input );
>> +    gcry_sexp_release( sexp_encrypted );
>> +    gcry_sexp_release( sexp_token_a );
>> +    gcry_mpi_release( mpi_pubkey );
>> +    gcry_mpi_release( mpi_exp );
>> +    gcry_mpi_release( mpi_input );
>> +    gcry_mpi_release( mpi_output );
>> +
>> +    return i_err;
>> +}
>
> I wonder if gcrypt allows releasing 'NULL'?

Yes, it checks for a value evaluating to true before freeing memory.

Regards,
Michael

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