====== EGD ======
%%FreeBSD%% has not needed the Perl Entropy Gathering Daemon [[https://en.wikipedia.org/wiki//dev/random#EGD_as_an_alternative|WikiPedia article]] since %%FreeBSD%% 4.2 and no Operating System that is supported by a vendor needs it any longer. EGD was only necessary for some commercial UNIX systems, versions that needed it all reached end of life.

^ OS ^ EGD needed until ^ OS released ^ End-of-support ^
| IRIX | 6.5.19 | Feb 2003 | Dec 2013 |
| Solaris | 2.6 | Jul 1997 | Jul 2006 |
| AIX | 5.2 | Oct 2002 | Apr 2009 |
| Tru64 | 5.1B | Sep 2002 | Dec 2012 |
| HP-UX | 11i v2 | Sep 2003 | Dec 2015 |

**TODO**: Properly format this info
As I recall, %%SunOS%% dlopen() is broken and is unsuitable for use in %%UnrealIRCd%% as well due to failing to properly handle dependency resolution. So that removes %%SunOS%% from the list.
So, basically:
IRIX, AIX, Tru64 - doesn't build with either available GCC or standard compiler, NO dlopen()
Solaris 2.x/%%SunOS%% - nothing resembling even gcc 2.95 is available, dlopen() is broken and unsuitable for use in the ircd
HP-UX - no shl_load() support in unrealircd, no build system support for HP's compiler

===== Observed as =====
Usually noticed as

''%%undefined reference to 'RAND_egd'%%''

in the compile output

===== Resolution =====
Remove the offending part

As of %%LibreSSL%% 2.2.0 %%LibreSSL%% added a define to make patching easier
''%%# define OPENSSL_NO_EGD%%''

"Guard" the code calling RAND_egd

<code>
#ifndef OPENSSL_NO_EGD
   RAND_egd("/some/file");
#endif
</code>

====== Deprecated des_ methods ======
%%OpenSSL%% has deprecated a large number of des_ methods and types on 24 October 2001([[https://github.com/openssl/openssl/commit/c2e4f17c1a0d4d5115c6ede9492de1615fe392ac|commit]]) and released this 30 December 2002 with [[https://github.com/openssl/openssl/blob/OpenSSL_0_9_7-stable/CHANGES|OpenSSL 0.9.7]].

%%LibreSSL%% removed des_old completely, and the next release of [[https://github.com/openssl/openssl/commit/24956ca00f014a917fb181a8abc39b349f3f316f|OpenSSL (1.0.3) has also removed]] these compatibility macros.

===== Observed as =====

''%%use of undeclared identifier 'des_cblock'; did you mean 'DES_cblock'?%%''

===== Resolution =====

  - Rename the des_ method or type to DES_ (don't forget to change C_Block -> DES_cblock)
  - Adapt the variables passed to the method (DES_ structs need to be passed as pointers, prefix the variable with ''%%&%%'')
The old compatibility macros can be found [[https://github.com/openssl/openssl/blob/OpenSSL_1_0_2-stable/crypto/des/des_old.h|here]]

**Example**

<code>
des_key_schedule ks1;
des_cblock iv1;

des_ncbc_encrypt(src, dst, len, ks1, iv1, DES_DECRYPT);
</code>

**Becomes**

<code>
DES_key_schedule ks1;
DES_cblock iv1;

DES_ncbc_encrypt(src, dst, len, &ks1, &iv1, DES_DECRYPT);
</code>

====== Uses removed Compression ======
%%LibreSSL%% disabled compression by default because of the number of attacks that use compression (CRIME, BREACH, BEAST).
%%LibreSSL%% does not include openssl/comp.h from openssl/ssl.h (and ssl3.h) leading to build failures\\ 
TLS v1.3 no longer supports compression (so just compress __before__ encryption)

===== Observed as =====
''%%unknown type name 'COMP_METHOD'%%'' or ''%%SSL_get_current_compression%%''

===== Resolution =====
==== Missing comp.h ====
First of all try and add

<code>
#include <openssl/comp.h>
</code>

to the code or header. There's no risk of re-defining methods/types %%%%''%%#ifndef HEADER_COMP_H%%''%%%%
==== SSL_NO_COMP vs OPENSSL_NO_COMP ====
If the %%OpenSSL%% library has been compiled without support for compression it defines
%%%%''%%OPENSSL_NO_COMP%%''%%%%
yet %%LibreSSL%% defines in opensslfeatures.h
%%%%''%%SSL_NO_COMP%%''%%%%
==== Remove/disable offending code ====
Remove offending code, preferably by using macros so this will still work with %%OpenSSL%% libs that do support compression

==== Example 1: Take care of defines ====
If the software has been created with care this will likely make the port just work when added in the right location

<code>
#include <openssl/opensslfeatures.h>
#include <openssl/comp.h>
#ifdef SSL_NO_COMP
#define OPENSSL_NO_COMP
#endif
</code>

==== Example 2: Disable code ====
If the software unconditionally relies on the existence of SSL compression you will need to add blocks of

<code>
#ifndef OPENSSL_NO_COMP
   /* Offending code */
#endif
</code>

====== SSLv2/SSLv3 method failures ======

Check the [[https://bugs.freebsd.org/195796|SSLv2 disabled]] exp-run results in the Bugs database. Contains interesting examples of fixes as well!

===== Observed as =====
Usually noticed as

<code>
ssl.c:73:30: warning: implicit declaration of function 'SSLv3_server_method' is invalid in C99 [-Wimplicit-function-declaration]
        ctx = SSL_CTX_new (server ? SSLv3_server_method() : SSLv3_client_method ());
</code>

in the build output. There's more than just these 2 SSLv3 methods.

===== Resolution =====

Sometimes you will find an example for OPENSSL_NO_SSL2 in the code, do something similar for SSLv3. This tends to use ''%%#ifdef%%'' guards around the SSLv2 or SSLv3 code.

Example ''%%SSLv3_server_method%%'' code

<code>
ctx = SSL_CTX_new (server ? SSLv3_server_method() : SSLv3_client_method ());
</code>

Becomes

<code>
#ifndef OPENSSL_NO_SSL3
ctx = SSL_CTX_new (server ? SSLv3_server_method() : SSLv3_client_method ());
#else
ctx = SSL_CTX_new (server ? SSLv23_server_method() : SSLv23_client_method ());
SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1|SSL_OP_NO_SSLv2);
#endif
</code>

This retains compatibility with !%%OpenSSL%% 0.9.8, 1.0.0 and 1.0.1

You **can** use ''%%SSLv23%%'' methods, these have been retained in %%LibreSSL%% but negotiate TLSv1, TLSv1.1 or TLSv1.2. What it will negotiate is controlled using the SSL_CTX_set_options. You will actually **improve** ports that you modify!\\ 

====== GOST engine ======
%%LibreSSL%% removed the GOST engine completely due to potentially problematic license. Later a partial reimplementation was added that does not

===== Observed as =====
Usually noticed as

''%%undefined reference to 'ENGINE_load_gost()'%%''

in the compile output

===== Resolution =====
Remove the offending part\\ 

Since %%OpenSSL%% comes with an OPENSSL_NO_GOST knob, ports seem to check for the availability of GOST. %%LibreSSL%% can also be compiled with NO_GOST so you need a different way of disabling GOST.

LIBRESS_VERSION_NUMBER should be available included from ''%%<openssl/opensslv.h>%%''

<code>
#if !defined(OPENSSL_NO_GOST) && OPENSSL_VERSION_NUMBER >= 0x1000001fL && !defined(LIBRESSL_VERSION_NUMBER)
   ENGINE_load_gost();
#endif
</code>

====== SHA-0 ======
Some ports require SHA-0 (EVP_sha)

===== Observed as =====

<code>
work/qca-2.1.0/plugins/qca-ossl/qca-ossl.cpp:7139:35: error: use of undeclared identifier 'EVP_sha'; did you mean 'EVP_sha1'?
    return new opensslHashContext( EVP_sha(), this, type);
                                   ^~~~~~~
                                   EVP_sha1
/usr/local/include/openssl/evp.h:658:15: note: 'EVP_sha1' declared here
const EVP_MD *EVP_sha1(void);
</code>

===== Resolution =====
"Guard" the offending code with an ''%%#ifndef%%'' block

<code>
#ifndef OPENSSL_NO_SHA0
    return new opensslHashContext( EVP_sha(), this, type);
#endif
</code>

====== Linking ======
Some ports don't properly link against ports' libcrypto

===== Observed as =====

<code>
# readelf -d work/stage/usr/local/bin/ipmitool
 0x0000000000000001 (NEEDED)             Shared library: [libcrypto.so.7]
</code>

===== Resolution =====
Add the following to the port's Makefile

<code>
CFLAGS+=	-I${OPENSSLINC}
LDFLAGS+=	-L${OPENSSLLIB}
</code>

Conditionally when %%OpenSSL%% support is conditional

Check that it works with readelf again

<code>
# readelf -d work/stage/usr/local/bin/ipmitool
 0x0000000000000001 (NEEDED)             Shared library: [libcrypto.so.32]
</code>