Re: improve ssl error code, 2147483650

Greetings,

* Heikki Linnakangas (hlinnaka(at)iki(dot)fi) wrote:
> On 07/03/2024 02:12, David Zhang wrote:
> > The SSL_CTX_load_verify_locations function in OpenSSL will return NULL
> > if there is a system error, such as "No such file or directory" in this
> > case:
> >
> > const char *ERR_reason_error_string(unsigned long e)
> > {
> >     ERR_STRING_DATA d, *p = NULL;
> >     unsigned long l, r;
> >
> >     if (!RUN_ONCE(&err_string_init, do_err_strings_init)) {
> >         return NULL;
> >     }
> >
> >     /*
> >      * ERR_reason_error_string() can't safely return system error strings,
> >      * since openssl_strerror_r() needs a buffer for thread safety, and we
> >      * haven't got one that would serve any sensible purpose.
> >      */
> >     if (ERR_SYSTEM_ERROR(e))
> >         return NULL;
>
> That's pretty unfortunate. As typical with OpenSSL, this stuff is not very
> well documented, but I think we could do something like this in
> SSLerrmessage():
>
> if (ERR_SYSTEM_ERROR(e))
> errreason = strerror(ERR_GET_REASON(e));
>
> ERR_SYSTEM_ERROR only exists in OpenSSL 3.0 and above, and the only
> documentation I could find was in this one obscure place in the man pages: https://www.openssl.org/docs/man3.2/man3/BIO_dgram_get_local_addr_enable.html.
> But as a best-effort thing, it would still be better than "SSL error code
> 2147483650".

Agreed that it doesn't seem well documented. I was trying to figure out
what the 'right' answer here was myself and not having much success. If
the above works, then +1 to that.

> > It would be better to perform a simple SSL file check before passing the
> > SSL file to OpenSSL APIs so that the system error can be captured and a
> > meaningful message provided to the end user.
>
> That feels pretty ugly. I agree it would catch most of the common mistakes
> in practice, so maybe we should just hold our noses and do it anyway, if the
> above ERR_SYSTEM_ERROR() method doesn't work.

Yeah, seems better to try and handle this the OpenSSL way ... if that's
possible to do.

> It's sad that we cannot pass a file descriptor or in-memory copy of the file
> contents to those functions.

Agreed.

Thanks!

Stephen