7 files changed, 448 insertions, 86 deletions
diff --git a/Swiften/TLS/OpenSSL/OpenSSLCertificate.cpp b/Swiften/TLS/OpenSSL/OpenSSLCertificate.cpp
index 17ac8cc..8d2d965 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLCertificate.cpp
+++ b/Swiften/TLS/OpenSSL/OpenSSLCertificate.cpp
@@ -30,7 +30,7 @@ OpenSSLCertificate::OpenSSLCertificate(const ByteArray& der) {
 #else
     const unsigned char* p = vecptr(der);
 #endif
-    cert = std::shared_ptr<X509>(d2i_X509(NULL, &p, der.size()), X509_free);
+    cert = std::shared_ptr<X509>(d2i_X509(nullptr, &p, der.size()), X509_free);
     if (!cert) {
         SWIFT_LOG(warning) << "Error creating certificate from DER data" << std::endl;
     }
@@ -42,7 +42,7 @@ ByteArray OpenSSLCertificate::toDER() const {
     if (!cert) {
         return result;
     }
-    result.resize(i2d_X509(cert.get(), NULL));
+    result.resize(i2d_X509(cert.get(), nullptr));
     unsigned char* p = vecptr(result);
     i2d_X509(cert.get(), &p);
     return result;
diff --git a/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.cpp b/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.cpp
new file mode 100644
index 0000000..c94702c
--- /dev/null
+++ b/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.cpp
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2018 Isode Limited.
+ * All rights reserved.
+ * See the COPYING file for more information.
+ */
+
+#include <Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h>
+
+#include <openssl/pem.h>
+
+namespace Swift {
+
+OpenSSLCertificateFactory::OpenSSLCertificateFactory() {
+}
+
+OpenSSLCertificateFactory::~OpenSSLCertificateFactory() {
+}
+
+Certificate* OpenSSLCertificateFactory::createCertificateFromDER(const ByteArray& der) {
+    return new OpenSSLCertificate(der);
+}
+
+std::vector<Certificate::ref> OpenSSLCertificateFactory::createCertificateChain(const ByteArray& data) {
+    std::vector<Certificate::ref> certificateChain;
+
+    if (data.size() > std::numeric_limits<int>::max()) {
+        return certificateChain;
+    }
+
+    auto bio = std::shared_ptr<BIO>(BIO_new(BIO_s_mem()), BIO_free);
+    BIO_write(bio.get(), vecptr(data), int(data.size()));
+
+    // Attempt parsing data as PEM
+    X509* openSSLCert = nullptr;
+    auto x509certFromPEM = PEM_read_bio_X509(bio.get(), &openSSLCert, nullptr, nullptr);
+    if (x509certFromPEM && openSSLCert) {
+        std::shared_ptr<X509> x509Cert(openSSLCert, X509_free);
+        certificateChain.push_back(std::make_shared<OpenSSLCertificate>(x509Cert));
+        openSSLCert = nullptr;
+        while ((x509certFromPEM = PEM_read_bio_X509(bio.get(), &openSSLCert, nullptr, nullptr)) != nullptr) {
+            std::shared_ptr<X509> x509Cert(openSSLCert, X509_free);
+            certificateChain.push_back(std::make_shared<OpenSSLCertificate>(x509Cert));
+            openSSLCert = nullptr;
+        }
+    }
+
+    return certificateChain;
+}
+
+}
diff --git a/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h b/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h
index c996cd5..af45a33 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h
+++ b/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2014 Isode Limited.
+ * Copyright (c) 2010-2018 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -12,8 +12,10 @@
 namespace Swift {
     class OpenSSLCertificateFactory : public CertificateFactory {
         public:
-            virtual Certificate* createCertificateFromDER(const ByteArray& der) {
-                return new OpenSSLCertificate(der);
-            }
+            OpenSSLCertificateFactory();
+            virtual ~OpenSSLCertificateFactory() override final;
+
+            virtual Certificate* createCertificateFromDER(const ByteArray& der) override final;
+            virtual std::vector<Certificate::ref> createCertificateChain(const ByteArray& data) override final;
     };
 }
diff --git a/Swiften/TLS/OpenSSL/OpenSSLContext.cpp b/Swiften/TLS/OpenSSL/OpenSSLContext.cpp
index 0805917..89917ee 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLContext.cpp
+++ b/Swiften/TLS/OpenSSL/OpenSSLContext.cpp
@@ -1,8 +1,9 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2018 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
+
 #include <Swiften/Base/Platform.h>
 
 #ifdef SWIFTEN_PLATFORM_WINDOWS
@@ -10,15 +11,21 @@
 #include <wincrypt.h>
 #endif
 
+#include <cassert>
+#include <memory>
 #include <vector>
+
+
+#include <openssl/bio.h>
 #include <openssl/err.h>
 #include <openssl/pkcs12.h>
-#include <memory>
 
 #if defined(SWIFTEN_PLATFORM_MACOSX)
 #include <Security/Security.h>
 #endif
 
+#include <Swiften/Base/Log.h>
+#include <Swiften/Base/Algorithm.h>
 #include <Swiften/TLS/OpenSSL/OpenSSLContext.h>
 #include <Swiften/TLS/OpenSSL/OpenSSLCertificate.h>
 #include <Swiften/TLS/CertificateWithKey.h>
@@ -39,10 +46,66 @@ static void freeX509Stack(STACK_OF(X509)* stack) {
     sk_X509_free(stack);
 }
 
-OpenSSLContext::OpenSSLContext() : state_(Start), context_(0), handle_(0), readBIO_(0), writeBIO_(0) {
+namespace {
+    class OpenSSLInitializerFinalizer {
+        public:
+            OpenSSLInitializerFinalizer() {
+                SSL_load_error_strings();
+                SSL_library_init();
+                OpenSSL_add_all_algorithms();
+
+                // Disable compression
+                /*
+                STACK_OF(SSL_COMP)* compressionMethods = SSL_COMP_get_compression_methods();
+                sk_SSL_COMP_zero(compressionMethods);*/
+            }
+
+            ~OpenSSLInitializerFinalizer() {
+                EVP_cleanup();
+            }
+
+            OpenSSLInitializerFinalizer(const OpenSSLInitializerFinalizer &) = delete;
+    };
+
+    std::unique_ptr<SSL_CTX> createSSL_CTX(OpenSSLContext::Mode mode) {
+        std::unique_ptr<SSL_CTX> sslCtx;
+        switch (mode) {
+            case OpenSSLContext::Mode::Client:
+                sslCtx = std::unique_ptr<SSL_CTX>(SSL_CTX_new(SSLv23_client_method()));
+                break;
+            case OpenSSLContext::Mode::Server:
+                sslCtx = std::unique_ptr<SSL_CTX>(SSL_CTX_new(SSLv23_server_method()));
+                break;
+        }
+        return sslCtx;
+    }
+
+    std::string openSSLInternalErrorToString() {
+        auto bio = std::shared_ptr<BIO>(BIO_new(BIO_s_mem()), BIO_free);
+        ERR_print_errors(bio.get());
+        std::string errorString;
+        errorString.resize(BIO_pending(bio.get()));
+        BIO_read(bio.get(), (void*)errorString.data(), errorString.size());
+        return errorString;
+    }
+ }
+
+OpenSSLContext::OpenSSLContext(Mode mode) : mode_(mode), state_(State::Start) {
     ensureLibraryInitialized();
-    context_ = SSL_CTX_new(SSLv23_client_method());
-    SSL_CTX_set_options(context_, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
+    context_ = createSSL_CTX(mode_);
+    SSL_CTX_set_options(context_.get(), SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
+
+    if (mode_ == Mode::Server) {
+#if OPENSSL_VERSION_NUMBER < 0x1010
+        // Automatically select highest preference curve used for ECDH temporary keys used during
+        // key exchange if possible.
+        // Since version 1.1.0, this option is always enabled.
+        SSL_CTX_set_ecdh_auto(context_.get(), 1);
+#endif
+
+        SSL_CTX_set_tlsext_servername_arg(context_.get(), this);
+        SSL_CTX_set_tlsext_servername_callback(context_.get(), OpenSSLContext::handleServerNameCallback);
+    }
 
     // TODO: implement CRL checking
     // TODO: download CRL (HTTP transport)
@@ -52,7 +115,7 @@ OpenSSLContext::OpenSSLContext() : state_(Start), context_(0), handle_(0), readB
     // TODO: handle OCSP stapling see https://www.rfc-editor.org/rfc/rfc4366.txt
     // Load system certs
 #if defined(SWIFTEN_PLATFORM_WINDOWS)
-    X509_STORE* store = SSL_CTX_get_cert_store(context_);
+    X509_STORE* store = SSL_CTX_get_cert_store(context_.get());
     HCERTSTORE systemStore = CertOpenSystemStore(0, "ROOT");
     if (systemStore) {
         PCCERT_CONTEXT certContext = NULL;
@@ -68,7 +131,7 @@ OpenSSLContext::OpenSSLContext() : state_(Start), context_(0), handle_(0), readB
         }
     }
 #elif !defined(SWIFTEN_PLATFORM_MACOSX)
-    SSL_CTX_set_default_verify_paths(context_);
+    SSL_CTX_set_default_verify_paths(context_.get());
 #elif defined(SWIFTEN_PLATFORM_MACOSX) && !defined(SWIFTEN_PLATFORM_IPHONE)
     // On Mac OS X 10.5 (OpenSSL < 0.9.8), OpenSSL does not automatically look in the system store.
     // On Mac OS X 10.6 (OpenSSL >= 0.9.8), OpenSSL *does* look in the system store to determine trust.
@@ -76,7 +139,7 @@ OpenSSLContext::OpenSSLContext() : state_(Start), context_(0), handle_(0), readB
     // the certificates first. See
     //        http://opensource.apple.com/source/OpenSSL098/OpenSSL098-27/src/crypto/x509/x509_vfy_apple.c
     // to understand why. We therefore add all certs from the system store ourselves.
-    X509_STORE* store = SSL_CTX_get_cert_store(context_);
+    X509_STORE* store = SSL_CTX_get_cert_store(context_.get());
     CFArrayRef anchorCertificates;
     if (SecTrustCopyAnchorCertificates(&anchorCertificates) == 0) {
         for (int i = 0; i < CFArrayGetCount(anchorCertificates); ++i) {
@@ -99,51 +162,96 @@ OpenSSLContext::OpenSSLContext() : state_(Start), context_(0), handle_(0), readB
 }
 
 OpenSSLContext::~OpenSSLContext() {
-    SSL_free(handle_);
-    SSL_CTX_free(context_);
 }
 
 void OpenSSLContext::ensureLibraryInitialized() {
-    static bool isLibraryInitialized = false;
-    if (!isLibraryInitialized) {
-        SSL_load_error_strings();
-        SSL_library_init();
-        OpenSSL_add_all_algorithms();
+    static OpenSSLInitializerFinalizer openSSLInit;
+}
 
-        // Disable compression
-        /*
-        STACK_OF(SSL_COMP)* compressionMethods = SSL_COMP_get_compression_methods();
-        sk_SSL_COMP_zero(compressionMethods);*/
+void OpenSSLContext::initAndSetBIOs() {
+    // Ownership of BIOs is transferred
+    readBIO_ = BIO_new(BIO_s_mem());
+    writeBIO_ = BIO_new(BIO_s_mem());
+    SSL_set_bio(handle_.get(), readBIO_, writeBIO_);
+}
 
-        isLibraryInitialized = true;
+void OpenSSLContext::accept() {
+    assert(mode_ == Mode::Server);
+    handle_ = std::unique_ptr<SSL>(SSL_new(context_.get()));
+    if (!handle_) {
+        state_ = State::Error;
+        onError(std::make_shared<TLSError>());
+        return;
     }
+
+    initAndSetBIOs();
+
+    state_ = State::Accepting;
+    doAccept();
 }
 
 void OpenSSLContext::connect() {
-    handle_ = SSL_new(context_);
-    if (handle_ == nullptr) {
-        state_ = Error;
+    connect(std::string());
+}
+
+void OpenSSLContext::connect(const std::string& requestedServerName) {
+    assert(mode_ == Mode::Client);
+    handle_ = std::unique_ptr<SSL>(SSL_new(context_.get()));
+    if (!handle_) {
+        state_ = State::Error;
         onError(std::make_shared<TLSError>());
         return;
     }
 
-    // Ownership of BIOs is ransferred
-    readBIO_ = BIO_new(BIO_s_mem());
-    writeBIO_ = BIO_new(BIO_s_mem());
-    SSL_set_bio(handle_, readBIO_, writeBIO_);
+    if (!requestedServerName.empty()) {
+        if (SSL_set_tlsext_host_name(handle_.get(), const_cast<char*>(requestedServerName.c_str())) != 1) {
+            SWIFT_LOG(error) << "Failed on SSL_set_tlsext_host_name()." << std::endl;
+        }
+    }
+
+    // Ownership of BIOs is transferred to the SSL_CTX instance in handle_.
+    initAndSetBIOs();
 
-    state_ = Connecting;
+    state_ = State::Connecting;
     doConnect();
 }
 
+void OpenSSLContext::doAccept() {
+    auto acceptResult = SSL_accept(handle_.get());
+    auto error = SSL_get_error(handle_.get(), acceptResult);
+    switch (error) {
+        case SSL_ERROR_NONE: {
+            state_ = State::Connected;
+            //std::cout << x->name << std::endl;
+            //const char* comp = SSL_get_current_compression(handle_.get());
+            //std::cout << "Compression: " << SSL_COMP_get_name(comp) << std::endl;
+            onConnected();
+            // The following call is important so the client knowns the handshake is finished.
+            sendPendingDataToNetwork();
+            break;
+        }
+        case SSL_ERROR_WANT_READ:
+            sendPendingDataToNetwork();
+            break;
+        case SSL_ERROR_WANT_WRITE:
+            sendPendingDataToNetwork();
+            break;
+        default:
+            SWIFT_LOG(warning) << openSSLInternalErrorToString() << std::endl;
+            state_ = State::Error;
+            onError(std::make_shared<TLSError>());
+            sendPendingDataToNetwork();
+    }
+}
+
 void OpenSSLContext::doConnect() {
-    int connectResult = SSL_connect(handle_);
-    int error = SSL_get_error(handle_, connectResult);
+    int connectResult = SSL_connect(handle_.get());
+    int error = SSL_get_error(handle_.get(), connectResult);
     switch (error) {
         case SSL_ERROR_NONE: {
-            state_ = Connected;
+            state_ = State::Connected;
             //std::cout << x->name << std::endl;
-            //const char* comp = SSL_get_current_compression(handle_);
+            //const char* comp = SSL_get_current_compression(handle_.get());
             //std::cout << "Compression: " << SSL_COMP_get_name(comp) << std::endl;
             onConnected();
             break;
@@ -152,11 +260,30 @@ void OpenSSLContext::doConnect() {
             sendPendingDataToNetwork();
             break;
         default:
-            state_ = Error;
+            SWIFT_LOG(warning) << openSSLInternalErrorToString() << std::endl;
+            state_ = State::Error;
             onError(std::make_shared<TLSError>());
     }
 }
 
+int OpenSSLContext::handleServerNameCallback(SSL* ssl, int*, void* arg) {
+    if (ssl == nullptr)
+        return SSL_TLSEXT_ERR_NOACK;
+
+    const char* servername = SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
+    if (servername) {
+        auto serverNameString = std::string(servername);
+        auto context = reinterpret_cast<OpenSSLContext*>(arg);
+        context->onServerNameRequested(serverNameString);
+
+        if (context->abortTLSHandshake_) {
+            context->abortTLSHandshake_ = false;
+            return SSL_TLSEXT_ERR_ALERT_FATAL;
+        }
+    }
+    return SSL_TLSEXT_ERR_OK;
+}
+
 void OpenSSLContext::sendPendingDataToNetwork() {
     int size = BIO_pending(writeBIO_);
     if (size > 0) {
@@ -170,23 +297,26 @@ void OpenSSLContext::sendPendingDataToNetwork() {
 void OpenSSLContext::handleDataFromNetwork(const SafeByteArray& data) {
     BIO_write(readBIO_, vecptr(data), data.size());
     switch (state_) {
-        case Connecting:
+        case State::Accepting:
+            doAccept();
+            break;
+        case State::Connecting:
             doConnect();
             break;
-        case Connected:
+        case State::Connected:
             sendPendingDataToApplication();
             break;
-        case Start: assert(false); break;
-        case Error: /*assert(false);*/ break;
+        case State::Start: assert(false); break;
+        case State::Error: /*assert(false);*/ break;
     }
 }
 
 void OpenSSLContext::handleDataFromApplication(const SafeByteArray& data) {
-    if (SSL_write(handle_, vecptr(data), data.size()) >= 0) {
+    if (SSL_write(handle_.get(), vecptr(data), data.size()) >= 0) {
         sendPendingDataToNetwork();
     }
     else {
-        state_ = Error;
+        state_ = State::Error;
         onError(std::make_shared<TLSError>());
     }
 }
@@ -194,19 +324,115 @@ void OpenSSLContext::handleDataFromApplication(const SafeByteArray& data) {
 void OpenSSLContext::sendPendingDataToApplication() {
     SafeByteArray data;
     data.resize(SSL_READ_BUFFERSIZE);
-    int ret = SSL_read(handle_, vecptr(data), data.size());
+    int ret = SSL_read(handle_.get(), vecptr(data), data.size());
     while (ret > 0) {
         data.resize(ret);
         onDataForApplication(data);
         data.resize(SSL_READ_BUFFERSIZE);
-        ret = SSL_read(handle_, vecptr(data), data.size());
+        ret = SSL_read(handle_.get(), vecptr(data), data.size());
     }
-    if (ret < 0 && SSL_get_error(handle_, ret) != SSL_ERROR_WANT_READ) {
-        state_ = Error;
+    if (ret < 0 && SSL_get_error(handle_.get(), ret) != SSL_ERROR_WANT_READ) {
+        state_ = State::Error;
         onError(std::make_shared<TLSError>());
     }
 }
 
+bool OpenSSLContext::setCertificateChain(const std::vector<Certificate::ref>& certificateChain) {
+    if (certificateChain.size() == 0) {
+        SWIFT_LOG(warning) << "Trying to load empty certificate chain." << std::endl;
+        return false;
+    }
+
+    // load endpoint certificate
+    auto openSSLCert = std::dynamic_pointer_cast<OpenSSLCertificate>(certificateChain[0]);
+    if (!openSSLCert) {
+        return false;
+    }
+
+    if (SSL_CTX_use_certificate(context_.get(), openSSLCert->getInternalX509().get()) != 1) {
+        return false;
+    }
+
+    if (certificateChain.size() > 1) {
+        for (auto certificate : range(certificateChain.begin() + 1, certificateChain.end())) {
+            auto openSSLCert = std::dynamic_pointer_cast<OpenSSLCertificate>(certificate);
+            if (!openSSLCert) {
+                return false;
+            }
+            if (SSL_CTX_add_extra_chain_cert(context_.get(), openSSLCert->getInternalX509().get()) != 1) {
+                SWIFT_LOG(warning) << "Trying to load empty certificate chain." << std::endl;
+                return false;
+            }
+        }
+    }
+
+    if (handle_) {
+        // This workaround is needed as OpenSSL has a shortcut to not do anything
+        // if you set the SSL_CTX to the existing SSL_CTX and not reloading the
+        // certificates from the SSL_CTX.
+        auto dummyContext = createSSL_CTX(mode_);
+        SSL_set_SSL_CTX(handle_.get(), dummyContext.get());
+        SSL_set_SSL_CTX(handle_.get(), context_.get());
+    }
+
+    return true;
+}
+
+int empty_or_preset_password_cb(char* buf, int max_len, int flag, void* password);
+
+int empty_or_preset_password_cb(char* buf, int max_len, int /* flag */, void* password) {
+    char* charPassword = (char*)password;
+    if (charPassword == nullptr) {
+        return 0;
+    }
+    int len = strlen(charPassword);
+    if(len > max_len) {
+        return 0;
+    }
+    memcpy(buf, charPassword, len);
+    return len;
+}
+
+bool OpenSSLContext::setPrivateKey(const PrivateKey::ref& privateKey) {
+    if (privateKey->getData().size() > std::numeric_limits<int>::max()) {
+        return false;
+    }
+
+    auto bio = std::shared_ptr<BIO>(BIO_new(BIO_s_mem()), BIO_free);
+    BIO_write(bio.get(), vecptr(privateKey->getData()), int(privateKey->getData().size()));
+
+    SafeByteArray safePassword;
+    void* password = nullptr;
+    if (privateKey->getPassword()) {
+        safePassword = privateKey->getPassword().get();
+        safePassword.push_back(0);
+        password = safePassword.data();
+    }
+    auto resultKey = PEM_read_bio_PrivateKey(bio.get(), nullptr, empty_or_preset_password_cb, password);
+    if (resultKey) {
+        if (handle_) {
+            auto result = SSL_use_PrivateKey(handle_.get(), resultKey);;
+            if (result != 1) {
+                return false;
+            }
+        }
+        else {
+            auto result = SSL_CTX_use_PrivateKey(context_.get(), resultKey);
+            if (result != 1) {
+                return false;
+            }
+        }
+    }
+    else {
+        return false;
+    }
+    return true;
+}
+
+void OpenSSLContext::setAbortTLSHandshake(bool abort) {
+    abortTLSHandshake_ = abort;
+}
+
 bool OpenSSLContext::setClientCertificate(CertificateWithKey::ref certificate) {
     std::shared_ptr<PKCS12Certificate> pkcs12Certificate = std::dynamic_pointer_cast<PKCS12Certificate>(certificate);
     if (!pkcs12Certificate || pkcs12Certificate->isNull()) {
@@ -216,16 +442,16 @@ bool OpenSSLContext::setClientCertificate(CertificateWithKey::ref certificate) {
     // Create a PKCS12 structure
     BIO* bio = BIO_new(BIO_s_mem());
     BIO_write(bio, vecptr(pkcs12Certificate->getData()), pkcs12Certificate->getData().size());
-    std::shared_ptr<PKCS12> pkcs12(d2i_PKCS12_bio(bio, NULL), PKCS12_free);
+    std::shared_ptr<PKCS12> pkcs12(d2i_PKCS12_bio(bio, nullptr), PKCS12_free);
     BIO_free(bio);
     if (!pkcs12) {
         return false;
     }
 
     // Parse PKCS12
-    X509 *certPtr = 0;
-    EVP_PKEY* privateKeyPtr = 0;
-    STACK_OF(X509)* caCertsPtr = 0;
+    X509 *certPtr = nullptr;
+    EVP_PKEY* privateKeyPtr = nullptr;
+    STACK_OF(X509)* caCertsPtr = nullptr;
     SafeByteArray password(pkcs12Certificate->getPassword());
     password.push_back(0);
     int result = PKCS12_parse(pkcs12.get(), reinterpret_cast<const char*>(vecptr(password)), &privateKeyPtr, &certPtr, &caCertsPtr);
@@ -237,21 +463,40 @@ bool OpenSSLContext::setClientCertificate(CertificateWithKey::ref certificate) {
     std::shared_ptr<STACK_OF(X509)> caCerts(caCertsPtr, freeX509Stack);
 
     // Use the key & certificates
-    if (SSL_CTX_use_certificate(context_, cert.get()) != 1) {
+    if (SSL_CTX_use_certificate(context_.get(), cert.get()) != 1) {
         return false;
     }
-    if (SSL_CTX_use_PrivateKey(context_, privateKey.get()) != 1) {
+    if (SSL_CTX_use_PrivateKey(context_.get(), privateKey.get()) != 1) {
         return false;
     }
     for (int i = 0;  i < sk_X509_num(caCerts.get()); ++i) {
-        SSL_CTX_add_extra_chain_cert(context_, sk_X509_value(caCerts.get(), i));
+        SSL_CTX_add_extra_chain_cert(context_.get(), sk_X509_value(caCerts.get(), i));
     }
     return true;
 }
 
+bool OpenSSLContext::setDiffieHellmanParameters(const ByteArray& parametersInOpenSslDer) {
+    auto bio = std::unique_ptr<BIO, decltype(&BIO_free)>(BIO_new(BIO_s_mem()), BIO_free);
+    if (bio) {
+        BIO_write(bio.get(), vecptr(parametersInOpenSslDer), parametersInOpenSslDer.size());
+        auto result = 0L;
+        if (auto dhparams = d2i_DHparams_bio(bio.get(), NULL)) {
+            if (handle_) {
+                result = SSL_set_tmp_dh(handle_.get(), dhparams);
+            }
+            else {
+                result = SSL_CTX_set_tmp_dh(context_.get(), dhparams);
+            }
+            DH_free(dhparams);
+        }
+        return result == 1;
+    }
+    return false;
+}
+
 std::vector<Certificate::ref> OpenSSLContext::getPeerCertificateChain() const {
     std::vector<Certificate::ref> result;
-    STACK_OF(X509)* chain = SSL_get_peer_cert_chain(handle_);
+    STACK_OF(X509)* chain = SSL_get_peer_cert_chain(handle_.get());
     for (int i = 0; i < sk_X509_num(chain); ++i) {
         std::shared_ptr<X509> x509Cert(X509_dup(sk_X509_value(chain, i)), X509_free);
 
@@ -262,7 +507,7 @@ std::vector<Certificate::ref> OpenSSLContext::getPeerCertificateChain() const {
 }
 
 std::shared_ptr<CertificateVerificationError> OpenSSLContext::getPeerCertificateVerificationError() const {
-    int verifyResult = SSL_get_verify_result(handle_);
+    int verifyResult = SSL_get_verify_result(handle_.get());
     if (verifyResult != X509_V_OK) {
         return std::make_shared<CertificateVerificationError>(getVerificationErrorTypeForResult(verifyResult));
     }
@@ -274,11 +519,19 @@ std::shared_ptr<CertificateVerificationError> OpenSSLContext::getPeerCertificate
 ByteArray OpenSSLContext::getFinishMessage() const {
     ByteArray data;
     data.resize(MAX_FINISHED_SIZE);
-    size_t size = SSL_get_finished(handle_, vecptr(data), data.size());
+    auto size = SSL_get_finished(handle_.get(), vecptr(data), data.size());
     data.resize(size);
     return data;
 }
 
+ByteArray OpenSSLContext::getPeerFinishMessage() const {
+    ByteArray data;
+    data.resize(MAX_FINISHED_SIZE);
+    auto size = SSL_get_peer_finished(handle_.get(), vecptr(data), data.size());
+    data.resize(size);
+    return data;
+ }
+
 CertificateVerificationError::Type OpenSSLContext::getVerificationErrorTypeForResult(int result) {
     assert(result != 0);
     switch (result) {
diff --git a/Swiften/TLS/OpenSSL/OpenSSLContext.h b/Swiften/TLS/OpenSSL/OpenSSLContext.h
index e75b3c9..cfa852a 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLContext.h
+++ b/Swiften/TLS/OpenSSL/OpenSSLContext.h
@@ -1,11 +1,13 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2018 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
 
 #pragma once
 
+#include <memory>
+
 #include <boost/noncopyable.hpp>
 #include <boost/signals2.hpp>
 
@@ -15,40 +17,69 @@
 #include <Swiften/TLS/CertificateWithKey.h>
 #include <Swiften/TLS/TLSContext.h>
 
-namespace Swift {
+namespace std {
+    template<>
+    class default_delete<SSL_CTX> {
+    public:
+        void operator()(SSL_CTX *ptr) {
+            SSL_CTX_free(ptr);
+        }
+    };
 
+    template<>
+    class default_delete<SSL> {
+    public:
+        void operator()(SSL *ptr) {
+            SSL_free(ptr);
+        }
+    };
+}
+
+namespace Swift {
     class OpenSSLContext : public TLSContext, boost::noncopyable {
         public:
-            OpenSSLContext();
-            virtual ~OpenSSLContext();
+            OpenSSLContext(Mode mode);
+            virtual ~OpenSSLContext() override final;
 
-            void connect();
-            bool setClientCertificate(CertificateWithKey::ref cert);
+            void accept() override final;
+            void connect() override final;
+            void connect(const std::string& requestHostname) override final;
 
-            void handleDataFromNetwork(const SafeByteArray&);
-            void handleDataFromApplication(const SafeByteArray&);
+            bool setCertificateChain(const std::vector<Certificate::ref>& certificateChain) override final;
+            bool setPrivateKey(const PrivateKey::ref& privateKey) override final;
+            bool setClientCertificate(CertificateWithKey::ref cert) override final;
+            void setAbortTLSHandshake(bool abort) override final;
+            bool setDiffieHellmanParameters(const ByteArray& parametersInOpenSslDer) override final;
 
-            std::vector<Certificate::ref> getPeerCertificateChain() const;
-            std::shared_ptr<CertificateVerificationError> getPeerCertificateVerificationError() const;
+            void handleDataFromNetwork(const SafeByteArray&) override final;
+            void handleDataFromApplication(const SafeByteArray&) override final;
 
-            virtual ByteArray getFinishMessage() const;
+            std::vector<Certificate::ref> getPeerCertificateChain() const override final;
+            std::shared_ptr<CertificateVerificationError> getPeerCertificateVerificationError() const override final;
+
+            virtual ByteArray getFinishMessage() const override final;
+            virtual ByteArray getPeerFinishMessage() const override final;
 
         private:
             static void ensureLibraryInitialized();
-
+            static int handleServerNameCallback(SSL *ssl, int *ad, void *arg);
             static CertificateVerificationError::Type getVerificationErrorTypeForResult(int);
 
+            void initAndSetBIOs();
+            void doAccept();
             void doConnect();
             void sendPendingDataToNetwork();
             void sendPendingDataToApplication();
 
         private:
-            enum State { Start, Connecting, Connected, Error };
+            enum class State { Start, Accepting, Connecting, Connected, Error };
 
+            const Mode mode_;
             State state_;
-            SSL_CTX* context_;
-            SSL* handle_;
-            BIO* readBIO_;
-            BIO* writeBIO_;
+            std::unique_ptr<SSL_CTX> context_;
+            std::unique_ptr<SSL> handle_;
+            BIO* readBIO_ = nullptr;
+            BIO* writeBIO_ = nullptr;
+            bool abortTLSHandshake_ = false;
     };
 }
diff --git a/Swiften/TLS/OpenSSL/OpenSSLContextFactory.cpp b/Swiften/TLS/OpenSSL/OpenSSLContextFactory.cpp
index 9f7b2aa..9d0ad72 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLContextFactory.cpp
+++ b/Swiften/TLS/OpenSSL/OpenSSLContextFactory.cpp
@@ -1,22 +1,48 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2018 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
 
 #include <Swiften/TLS/OpenSSL/OpenSSLContextFactory.h>
 
+#include <openssl/bio.h>
+#include <openssl/dh.h>
+#include <openssl/pem.h>
+
 #include <Swiften/Base/Log.h>
 #include <Swiften/TLS/OpenSSL/OpenSSLContext.h>
 
+#pragma clang diagnostic ignored "-Wshorten-64-to-32"
+
 namespace Swift {
 
 bool OpenSSLContextFactory::canCreate() const {
     return true;
 }
 
-TLSContext* OpenSSLContextFactory::createTLSContext(const TLSOptions&) {
-    return new OpenSSLContext();
+TLSContext* OpenSSLContextFactory::createTLSContext(const TLSOptions&, TLSContext::Mode mode) {
+    return new OpenSSLContext(mode);
+}
+
+ByteArray OpenSSLContextFactory::convertDHParametersFromPEMToDER(const std::string& dhParametersInPEM) {
+    ByteArray dhParametersInDER;
+
+    auto bio = std::unique_ptr<BIO, decltype(&BIO_free)>(BIO_new(BIO_s_mem()), BIO_free);
+    if (bio) {
+        BIO_write(bio.get(), dhParametersInPEM.data(), dhParametersInPEM.size());
+        if (auto params = PEM_read_bio_DHparams(bio.get(), nullptr, nullptr, nullptr)) {
+            unsigned char* buffer = nullptr;
+            auto len = i2d_DHparams(params, &buffer);
+            if (len > 0) {
+                dhParametersInDER = createByteArray(buffer, static_cast<size_t>(len));
+                free(buffer);
+            }
+            DH_free(params);
+
+        }
+    }
+    return dhParametersInDER;
 }
 
 void OpenSSLContextFactory::setCheckCertificateRevocation(bool check) {
diff --git a/Swiften/TLS/OpenSSL/OpenSSLContextFactory.h b/Swiften/TLS/OpenSSL/OpenSSLContextFactory.h
index e121a1a..db7fa34 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLContextFactory.h
+++ b/Swiften/TLS/OpenSSL/OpenSSLContextFactory.h
@@ -1,23 +1,23 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2018 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
 
 #pragma once
 
-#include <cassert>
-
 #include <Swiften/TLS/TLSContextFactory.h>
 
 namespace Swift {
     class OpenSSLContextFactory : public TLSContextFactory {
         public:
-            bool canCreate() const;
-            virtual TLSContext* createTLSContext(const TLSOptions& tlsOptions);
+            bool canCreate() const override final;
+            virtual TLSContext* createTLSContext(const TLSOptions& tlsOptions, TLSContext::Mode mode) override final;
+
+            virtual ByteArray convertDHParametersFromPEMToDER(const std::string& dhParametersInPEM) override final;
 
             // Not supported
-            virtual void setCheckCertificateRevocation(bool b);
-            virtual void setDisconnectOnCardRemoval(bool b);
+            virtual void setCheckCertificateRevocation(bool b) override final;
+            virtual void setDisconnectOnCardRemoval(bool b) override final;
     };
 }