////  WebRTCOpenSSLCompatibility.cpp//  libraries/networking/src////  Created by Dale Glass on 25/05/2022//  Copyright 2022 Vircadia contributors.////  Distributed under the Apache License, Version 2.0.//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html//   #include <openssl/opensslv.h> /* * Starting at OpenSSL 3.0, the names for some of the functions changed. * * This breaks WebRTC. We have a problem: * * WebRTC is a pain to build and has its own build environment. Rather than building it * locally we provide a prebuilt binary. Said binary is generated against some Google-provided * chroot of Debian, so for the most part the result is independent of what you build it * on anyway. * * WebRTC prefers to build and use its own BoringSSL. But we use OpenSSL, and symbol * names collide between what comes from the BoringSSL linked into webrtc, and our * system library. * * Therefore, we use the option to link WebRTC against the system OpenSSL. However, * starting on OpenSSL 3.0, some symbols were renamed. Backwards compatibility is kept * through #defines in the OpenSSL headers, but of course this has no effect on compiled * code. We have a WebRTC that calls SSL_get_peer_certificate, but the new OpenSSL now calls * this SSL_get1_peer_certificate. * * New distros using OpenSSL 3.0 now have problems. * * * We have these possible solutions: * * 1. Have an OpenSSL 3.0 build of WebRTC, and choose which we need. Possible, but a bit painful * while OpenSSL 1.x is still in use. * * 2. Follow the recommendation here: * https://stackoverflow.com/questions/71107066/how-to-integrate-part-of-webrtc-as-a-static-dynamic-library-with-the-existing * and create a wrapper for WebRTC to make sure the library only exposes a minimal interface and stops * conflicting with other things. Then it can be built with BoringSSL and not bother anything else. * * 3. Try to hack around the issue, which is what we do here, by just providing compatibility wrappers * for the missing functions. This is a very simple solution that should work perfectly fine for * the time being, so long binary compatibility hasn't been broken somewhere. */#if defined(OPENSSL_VERSION_MAJOR) && OPENSSL_VERSION_MAJOR >= 3 #include <openssl/ssl.h> // These are defined in the OpenSSL headers as aliases for the new names.// We have to get rid of them so that we can make actual functions with such names.#undef SSL_get_peer_certificate#undef EVP_MD_size#undef EVP_MD_type extern "C" {    X509 *SSL_get_peer_certificate(const SSL *ssl) {        return SSL_get1_peer_certificate(ssl);    }     int EVP_MD_size(const EVP_MD *md) {        return EVP_MD_get_size(md);    }     int EVP_MD_type(const EVP_MD *md) {        return EVP_MD_get_type(md);    }} #endif