[tor-relays] building Tor against LibreSSL 2.1.1 fails with "undefined reference to `EVP_aes_128_ctr'" error

[Nick Mathewson]

On Wed, Dec 24, 2014 at 5:15 PM, Seth <list at sysfu.com> wrote:
> On Tue, 23 Dec 2014 09:16:56 -0800, Nick Mathewson <nickm at freehaven.net>
> wrote:
>>
>> Strange!  There is code in git master that is supposed to prevent
>> this.
>
>
> Yes, I thought it had been fixed by your commit from this ticket
> https://trac.torproject.org/projects/tor/ticket/13325
>
>> The current Tor's "find_cipher_by_id" is supposed to avoid
>> looking at the get_cipher_by_id field.  Do you really get the same
>> errors with master, or is the error different?
>
>
> Makes no difference, same error for master branch as the rest.
>
> latest Git - master branch - git clone https://git.torproject.org/git/tor
> -------------------------------------------------------------------------
>
> # cd tor; git status
> On branch master
> Your branch is up-to-date with 'origin/master'.
> nothing to commit, working directory clean
>
> # sh autogen.sh ; ./configure --with-openssl-dir=/usr/local
> --disable-asciidoc ; make
>
> src/common/tortls.c: In function 'find_cipher_by_id':
> src/common/tortls.c:1478: error: 'SSL_METHOD' has no member named
> 'get_cipher_by_char'
> src/common/tortls.c:1484: error: 'SSL_METHOD' has no member named
> 'get_cipher_by_char'
> *** [src/common/tortls.o] Error code 1

Huh.  So, that code is wrapped inside a block that does

#ifdef HAVE_STRUCT_SSL_METHOD_ST_GET_CIPHER_BY_CHAR

And that macro is supposed to be defined by autoconf if it sees the
get_cipher_by_char method in SSL_METHOD_ST.

Hm.  Maybe the problem is in our (notoriously wonky) SSL library detection!

Maybe the autoconf script is looking at the headers in /usr/include,
instead of /usr/local/include ? That would mess it up.

Instead of using --with-openssl-dir=/usr/local, what happens if you
set CFLAGS and LDFLAGS by hand when compiling?

If that works, then the underlying bug here is actually the library
detection issues in
   https://trac.torproject.org/projects/tor/ticket/13817

For the meantime, is there a compiler macro we can use to distinguish
libressl from openssl at compile-time?