--- CMakeLists.txt.orig 2021-12-01 02:41:05 UTC
+++ CMakeLists.txt
@@ -82,6 +82,20 @@ endmacro()
 tristate_option(OPENSSL "Support SSL")
 if(WANT_OPENSSL)
        find_package(OpenSSL ${TRISTATE_OPENSSL_REQUIRED})
+
+       if(OPENSSL_FOUND)
+               # SSL_SESSION was made opaque in OpenSSL 1.1.0;
+               # LibreSSL gained that function later too.
+               # TODO: maybe remove this check at some point, and stop supporting old
+               # libssl versions
+               function(check_SSL_SESSION_get0_cipher)
+                       set(CMAKE_REQUIRED_LIBRARIES ${OPENSSL_LIBRARIES})
+                       set(CMAKE_REQUIRED_INCLUDES ${OPENSSL_INCLUDE_DIR})
+                       check_cxx_symbol_exists(SSL_SESSION_get0_cipher openssl/ssl.h
+                               HAVE_SSL_SESSION_get0_cipher)
+               endfunction()
+               check_SSL_SESSION_get0_cipher()
+       endif()
 endif()
 set(HAVE_LIBSSL "${OPENSSL_FOUND}")

--- include/znc/zncconfig.h.cmake.in.orig       2021-12-01 02:42:16 UTC
+++ include/znc/zncconfig.h.cmake.in
@@ -31,6 +31,7 @@
 #define HAVE_PTHREAD 1
 #cmakedefine HAVE_THREADED_DNS 1
 #cmakedefine HAVE_LIBSSL 1
+#cmakedefine HAVE_SSL_SESSION_get0_cipher 1
 #cmakedefine HAVE_IPV6 1
 #cmakedefine HAVE_ZLIB 1
 #cmakedefine HAVE_I18N 1
--- modules/schat.cpp.orig      2021-12-01 02:42:43 UTC
+++ modules/schat.cpp
@@ -25,8 +25,7 @@
 #include <znc/User.h>
 #include <znc/IRCNetwork.h>

-#if !defined(OPENSSL_VERSION_NUMBER) || defined(LIBRESSL_VERSION_NUMBER) || \
-    OPENSSL_VERSION_NUMBER < 0x10100007
+#ifndef HAVE_SSL_SESSION_get0_cipher
 /* SSL_SESSION was made opaque in OpenSSL 1.1.0, cipher accessor was added 2
 weeks before the public release.
 See openssl/openssl@e92813234318635639dba0168c7ef5568757449b. */