> On 2014/12/09 07:37, Brent Cook wrote:
>> If an app calls a function, it should probably check if that function
>> exists during configuration time, rather than inferring if define A
>> exists, function B and C must exist. Especially things that are just
>> protocol constant definitions. If they are using autoconf, a call to
>> AC_CHECK_FUNCS would be better, IMHO.
>
> Neither nginx nor haproxy use autoconf. nginx has it's own config
> testing infrastructure where this could be added, though they appear
> to be deliberately trying to keep the maze of #ifdef and configuration
> tests to a minimum. haproxy has a simple Makefile with USE_* flags
> set for different system types, it's quite clean and straightforward
> but doesn't allow for this type of test.

Thats correct indeed.

I believe a not to be underestimated amount of applications #ifdef's
certain functionality of openssl out, for example NPN
(SSL_CTRL_SET_TLSEXT_HOSTNAME) or server preferential cipher ordering
(SSL_OP_CIPHER_SERVER_PREFERENCE).

In fact if I'm not mistaken that is exactly the reason why both 
LibreSSL [1] and BoringSSL [2] have "opensslfeatures.h".



> But, I believe jsing@ has a patch in-review to merge the rest ALPN
> support any way.

Great, thanks!



[1] 
https://github.com/libressl-portable/openbsd/blob/master/src/lib/libssl/src/crypto/opensslfeatures.h
[2] 
https://boringssl.googlesource.com/boringssl/+/987b8f1e715414b0b278a4a0c64ec9c97ad65f58%5E!/


                                          

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