[tor-dev] Trivial patch: avoid redundant calls to ENGINE_register_all_complete

[coderman]

i was able to confirm the expected behavior using the BADRAND engine
attached to same ticket:
  https://trac.torproject.org/projects/tor/ticket/10402

and also here (do trac tickets ever go away / get deleted?):
  https://peertech.org/dist/openssl-1.0.1e-badrand-test.patch

currently Tor on 1.0.1+ will invoke a chain like:

Dec 18 13:59:22.000 [info] crypto_global_init(): Initializing OpenSSL
engine support.
ENGINE_load_builtin_engines called.
ENGINE_register_all_complete invoked.
ENGINE_register_complete invoked for rsax.
ENGINE_register_complete invoked for dynamic.
ENGINE_register_all_complete invoked.
ENGINE_register_complete invoked for rsax.
ENGINE_register_complete invoked for dynamic.
.
.

due to the redundant call to  ENGINE_register_all_complete. once
patched per above, the call sequence is the expected:
Dec 18 14:32:25.000 [info] crypto_global_init(): Initializing OpenSSL
engine support.
ENGINE_load_builtin_engines called.
ENGINE_register_all_complete invoked.
ENGINE_register_complete invoked for rsax.
ENGINE_register_complete invoked for dynamic.
.
.

log file from successul run post-patch above:
 https://peertech.org/dist/tor-no-repeat-register-run.txt


best regards,


On Wed, Dec 18, 2013 at 9:57 AM, coderman <coderman at gmail.com> wrote:
> hello all, Nick,
>
> per the other thread in tor-talk about RDRAND, this is the minor fix
> for OpenSSL 1.0.1+ mentioned.
>
> i don't know that this is useful, and i am still giving the engine
> code a thorough review per Nick's other feedback: "Above all, do not
> assume
> that you understand how OpenSSL works until you have investigated with
> a debugger, the source code, and a pot of coffee." :)
>
>
> best regards,
>
> ---
>
>
> diff --git a/src/common/crypto.c b/src/common/crypto.c
> index 5afb98e..7c02ea4 100644
> --- a/src/common/crypto.c
> +++ b/src/common/crypto.c
> @@ -282,7 +282,10 @@ crypto_global_init(int useAccel, const char
> *accelName, const char *accelDir)
>
>        log_info(LD_CRYPTO, "Initializing OpenSSL engine support.");
>        ENGINE_load_builtin_engines();
> -      ENGINE_register_all_complete();
> +      /* OpenSSL 1.0.1 and newer register complete when engines loaded. */
> +      if (SSLeay() < OPENSSL_V_SERIES(1,0,1)) {
> +        ENGINE_register_all_complete();
> +      }
>
>        if (accelName) {
>          if (accelDir) {