8 files changed, 359 insertions, 63 deletions
diff --git a/Swiften/TLS/OpenSSL/OpenSSLCertificate.cpp b/Swiften/TLS/OpenSSL/OpenSSLCertificate.cpp
index 8d2d965..66b650d 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLCertificate.cpp
+++ b/Swiften/TLS/OpenSSL/OpenSSLCertificate.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2016 Isode Limited.
+ * Copyright (c) 2010-2019 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -32,11 +32,19 @@ OpenSSLCertificate::OpenSSLCertificate(const ByteArray& der) {
 #endif
     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;
+//        SWIFT_LOG(warning) << "Error creating certificate from DER data";
     }
     parse();
 }
 
+void OpenSSLCertificate::incrementReferenceCount() const {
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+    X509_up_ref(cert.get());
+#else
+    CRYPTO_add(&(cert.get()->references), 1, CRYPTO_LOCK_EVP_PKEY);
+#endif
+}
+
 ByteArray OpenSSLCertificate::toDER() const {
     ByteArray result;
     if (!cert) {
diff --git a/Swiften/TLS/OpenSSL/OpenSSLCertificate.h b/Swiften/TLS/OpenSSL/OpenSSLCertificate.h
index 186caea..64da82a 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLCertificate.h
+++ b/Swiften/TLS/OpenSSL/OpenSSLCertificate.h
@@ -45,6 +45,8 @@ namespace Swift {
                 return cert;
             }
 
+            void incrementReferenceCount() const;
+
         private:
             void parse();
 
diff --git a/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.cpp b/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.cpp
index 5eb626b..73058a5 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.cpp
+++ b/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.cpp
@@ -7,6 +7,7 @@
 #include <Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h>
 
 #include <openssl/pem.h>
+#include <openssl/err.h>
 
 namespace Swift {
 
@@ -20,8 +21,8 @@ Certificate* OpenSSLCertificateFactory::createCertificateFromDER(const ByteArray
     return new OpenSSLCertificate(der);
 }
 
-std::vector<std::unique_ptr<Certificate>> OpenSSLCertificateFactory::createCertificateChain(const ByteArray& data) {
-    std::vector<std::unique_ptr<Certificate>> certificateChain;
+std::vector<std::shared_ptr<Certificate>> OpenSSLCertificateFactory::createCertificateChain(const ByteArray& data) {
+    std::vector<std::shared_ptr<Certificate>> certificateChain;
 
     if (data.size() > std::numeric_limits<int>::max()) {
         return certificateChain;
@@ -35,15 +36,20 @@ std::vector<std::unique_ptr<Certificate>> OpenSSLCertificateFactory::createCerti
     auto x509certFromPEM = PEM_read_bio_X509(bio.get(), &openSSLCert, nullptr, nullptr);
     if (x509certFromPEM && openSSLCert) {
         std::shared_ptr<X509> x509Cert(openSSLCert, X509_free);
-        certificateChain.emplace_back(std::make_unique<OpenSSLCertificate>(x509Cert));
+        certificateChain.emplace_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.emplace_back(std::make_unique<OpenSSLCertificate>(x509Cert));
+            certificateChain.emplace_back(std::make_shared<OpenSSLCertificate>(x509Cert));
             openSSLCert = nullptr;
         }
     }
 
+    // Clear any (expected) errors which resulted from PEM parsing
+    // If we don't do this, any existing TLS context will detect these
+    // spurious errors and fail to work
+    ERR_clear_error();
+
     return certificateChain;
 }
 
diff --git a/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h b/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h
index 48e9b2c..a6974c8 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h
+++ b/Swiften/TLS/OpenSSL/OpenSSLCertificateFactory.h
@@ -16,6 +16,6 @@ namespace Swift {
             virtual ~OpenSSLCertificateFactory() override final;
 
             virtual Certificate* createCertificateFromDER(const ByteArray& der) override final;
-            virtual std::vector<std::unique_ptr<Certificate>> createCertificateChain(const ByteArray& data) override final;
+            virtual std::vector<std::shared_ptr<Certificate>> createCertificateChain(const ByteArray& data) override final;
     };
 }
diff --git a/Swiften/TLS/OpenSSL/OpenSSLContext.cpp b/Swiften/TLS/OpenSSL/OpenSSLContext.cpp
index 5692e74..86b0504 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLContext.cpp
+++ b/Swiften/TLS/OpenSSL/OpenSSLContext.cpp
@@ -42,6 +42,14 @@ namespace Swift {
 static const int MAX_FINISHED_SIZE = 4096;
 static const int SSL_READ_BUFFERSIZE = 8192;
 
+#define SSL_DEFAULT_VERIFY_DEPTH 5
+
+// Callback function declarations for certificate verification
+extern "C" {
+    static int certVerifyCallback(X509_STORE_CTX *store_ctx, void*);
+    static int verifyCallback(int preverify_ok, X509_STORE_CTX *ctx);
+}
+
 static void freeX509Stack(STACK_OF(X509)* stack) {
     sk_X509_free(stack);
 }
@@ -90,7 +98,7 @@ namespace {
     }
  }
 
-OpenSSLContext::OpenSSLContext(Mode mode) : mode_(mode), state_(State::Start) {
+OpenSSLContext::OpenSSLContext(const TLSOptions& options, Mode mode) : mode_(mode), state_(State::Start) {
     ensureLibraryInitialized();
     context_ = createSSL_CTX(mode_);
     SSL_CTX_set_options(context_.get(), SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
@@ -113,52 +121,58 @@ OpenSSLContext::OpenSSLContext(Mode mode) : mode_(mode), state_(State::Start) {
 
     // TODO: implement OCSP support
     // TODO: handle OCSP stapling see https://www.rfc-editor.org/rfc/rfc4366.txt
-    // Load system certs
+
+    // Default for ignoreSystemTrustAnchors is false, i.e. load System TAs by default,
+    // to preserve previous behaviour
+    if (!options.ignoreSystemTrustAnchors) {
+        // Load system certs
 #if defined(SWIFTEN_PLATFORM_WINDOWS)
-    X509_STORE* store = SSL_CTX_get_cert_store(context_.get());
-    HCERTSTORE systemStore = CertOpenSystemStore(0, "ROOT");
-    if (systemStore) {
-        PCCERT_CONTEXT certContext = NULL;
-        while (true) {
-            certContext = CertFindCertificateInStore(systemStore, X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, 0, CERT_FIND_ANY, NULL, certContext);
-            if (!certContext) {
-                break;
-            }
-            OpenSSLCertificate cert(createByteArray(certContext->pbCertEncoded, certContext->cbCertEncoded));
-            if (store && cert.getInternalX509()) {
-                X509_STORE_add_cert(store, cert.getInternalX509().get());
+        X509_STORE* store = SSL_CTX_get_cert_store(context_.get());
+        HCERTSTORE systemStore = CertOpenSystemStore(0, "ROOT");
+        if (systemStore) {
+            PCCERT_CONTEXT certContext = nullptr;
+            while (true) {
+                certContext = CertFindCertificateInStore(systemStore, X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, 0, CERT_FIND_ANY, nullptr, certContext);
+                if (!certContext) {
+                    break;
+                }
+                OpenSSLCertificate cert(createByteArray(certContext->pbCertEncoded, certContext->cbCertEncoded));
+                if (store && cert.getInternalX509()) {
+                    X509_STORE_add_cert(store, cert.getInternalX509().get());
+                }
             }
         }
-    }
 #elif !defined(SWIFTEN_PLATFORM_MACOSX)
-    SSL_CTX_set_default_verify_paths(context_.get());
+        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.
-    // However, if there is a certificate error, it will always emit the "Invalid CA" error if we didn't add
-    // 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_.get());
-    CFArrayRef anchorCertificates;
-    if (SecTrustCopyAnchorCertificates(&anchorCertificates) == 0) {
-        for (int i = 0; i < CFArrayGetCount(anchorCertificates); ++i) {
-            SecCertificateRef cert = reinterpret_cast<SecCertificateRef>(const_cast<void*>(CFArrayGetValueAtIndex(anchorCertificates, i)));
-            CSSM_DATA certCSSMData;
-            if (SecCertificateGetData(cert, &certCSSMData) != 0 || certCSSMData.Length == 0) {
-                continue;
-            }
-            std::vector<unsigned char> certData;
-            certData.resize(certCSSMData.Length);
-            memcpy(&certData[0], certCSSMData.Data, certCSSMData.Length);
-            OpenSSLCertificate certificate(certData);
-            if (store && certificate.getInternalX509()) {
-                X509_STORE_add_cert(store, certificate.getInternalX509().get());
+        // 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.
+        // However, if there is a certificate error, it will always emit the "Invalid CA" error if we didn't add
+        // 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_.get());
+        CFArrayRef anchorCertificates;
+        if (SecTrustCopyAnchorCertificates(&anchorCertificates) == 0) {
+            for (int i = 0; i < CFArrayGetCount(anchorCertificates); ++i) {
+                SecCertificateRef cert = reinterpret_cast<SecCertificateRef>(const_cast<void*>(CFArrayGetValueAtIndex(anchorCertificates, i)));
+                CSSM_DATA certCSSMData;
+                if (SecCertificateGetData(cert, &certCSSMData) != 0 || certCSSMData.Length == 0) {
+                    continue;
+                }
+                std::vector<unsigned char> certData;
+                certData.resize(certCSSMData.Length);
+                memcpy(&certData[0], certCSSMData.Data, certCSSMData.Length);
+                OpenSSLCertificate certificate(certData);
+                if (store && certificate.getInternalX509()) {
+                    X509_STORE_add_cert(store, certificate.getInternalX509().get());
+                }
             }
+            CFRelease(anchorCertificates);
         }
-        CFRelease(anchorCertificates);
-    }
 #endif
+    }
+    configure(options);
 }
 
 OpenSSLContext::~OpenSSLContext() {
@@ -175,6 +189,241 @@ void OpenSSLContext::initAndSetBIOs() {
     SSL_set_bio(handle_.get(), readBIO_, writeBIO_);
 }
 
+// This callback is called by OpenSSL when a client certificate needs to be verified.
+// In turn, this calls the verification callback which the user
+// of this OpenSSLContext has configured (if any).
+static int certVerifyCallback(X509_STORE_CTX* store_ctx, void* arg)
+{
+    OpenSSLContext* context = static_cast<OpenSSLContext *>(arg);
+
+    // Need to stash store_ctx pointer for use within verification
+    context->setX509StoreContext(store_ctx);
+
+    int ret;
+
+    // This callback shouldn't have been set up if the context doesn't
+    // have a verifyCertCallback set, but it doesn't hurt to double check
+    std::function<int (const TLSContext *)> cb = context->getVerifyCertCallback();
+    if (cb != nullptr) {
+        ret = cb(static_cast<const OpenSSLContext*>(context));
+    } else {
+        SWIFT_LOG(debug) << "certVerifyCallback called but context.verifyCertCallback is unset";
+        ret = 0;
+    }
+
+    context->setX509StoreContext(nullptr);
+    return ret;
+}
+
+// Convenience function to generate a text representation
+// of an X509 Name. This information is only used for logging.
+static std::string X509_NAME_to_text(X509_NAME* name)
+{
+    std::string nameString;
+
+    if (!name) {
+        return nameString;
+    }
+
+    std::unique_ptr<BIO, decltype(&BIO_free)> io(BIO_new(BIO_s_mem()), &BIO_free);
+    int r = X509_NAME_print_ex(io.get(), name, 0, XN_FLAG_RFC2253);
+    BIO_write(io.get(), "\0", 1);
+
+    if (r > 0) {
+        BUF_MEM* ptr = nullptr;
+        BIO_get_mem_ptr(io.get(), &ptr);
+        nameString = ptr->data;
+    }
+
+    return nameString;
+}
+
+// Check depth of certificate chain
+static int verifyCallback(int preverifyOk, X509_STORE_CTX* ctx)
+{
+    // Retrieve the pointer to the SSL of the connection currently treated
+    // and the application specific data stored into the SSL object.
+
+    int err = X509_STORE_CTX_get_error(ctx);
+    int depth = X509_STORE_CTX_get_error_depth(ctx);
+
+    SSL* ssl = static_cast<SSL*>(X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx()));
+    SSL_CTX* sslctx = ssl ? SSL_get_SSL_CTX(ssl) : nullptr;
+    if (!sslctx) {
+        SWIFT_LOG(debug) << "verifyCallback: internal error";
+        return preverifyOk;
+    }
+
+    if (SSL_CTX_get_verify_mode(sslctx) == SSL_VERIFY_NONE) {
+        SWIFT_LOG(debug) << "verifyCallback: no verification required";
+        // No verification requested
+        return 1;
+    }
+
+    X509* errCert = X509_STORE_CTX_get_current_cert(ctx);
+    std::string subjectString;
+    if (errCert) {
+        X509_NAME* subjectName = X509_get_subject_name(errCert);
+        subjectString = X509_NAME_to_text(subjectName);
+    }
+
+    // Catch a too long certificate chain. The depth limit set using
+    // SSL_CTX_set_verify_depth() is by purpose set to "limit+1" so
+    // that whenever the "depth>verify_depth" condition is met, we
+    // have violated the limit and want to log this error condition.
+    // We must do it here, because the CHAIN_TOO_LONG error would not
+    // be found explicitly; only errors introduced by cutting off the
+    // additional certificates would be logged.
+    if (depth >= SSL_CTX_get_verify_depth(sslctx)) {
+        preverifyOk = 0;
+        err = X509_V_ERR_CERT_CHAIN_TOO_LONG;
+        X509_STORE_CTX_set_error(ctx, err);
+    }
+
+    if (!preverifyOk) {
+        std::string issuerString;
+        if (errCert) {
+            X509_NAME* issuerName = X509_get_issuer_name(errCert);
+            issuerString = X509_NAME_to_text(issuerName);
+        }
+        SWIFT_LOG(debug) << "verifyCallback: verification error " <<
+          X509_verify_cert_error_string(err) << " depth: " <<
+          depth << " issuer: " << ((issuerString.length() > 0) ? issuerString : "<unknown>");
+     } else {
+        SWIFT_LOG(debug) << "verifyCallback: SSL depth: " << depth << " Subject: " <<
+          ((subjectString.length() > 0) ? subjectString : "<>");
+    }
+    // Always return "OK", as check on verification status
+    // will be performed once TLS handshake has completed,
+    // by calling OpenSSLContext::getVerificationErrorTypeForResult() to
+    // get the value set via X509_STORE_CTX_set_error() above.
+    return 1;
+}
+
+bool OpenSSLContext::configure(const TLSOptions &options)
+{
+    if (options.cipherSuites) {
+        std::string cipherSuites = *(options.cipherSuites);
+        if (SSL_CTX_set_cipher_list(context_.get(), cipherSuites.c_str()) != 1 ) {
+            SWIFT_LOG(debug) << "Failed to set cipher-suites";
+            return false;
+        }
+    }
+
+    if (options.context) {
+        const auto& contextId = *options.context;
+
+        if (SSL_CTX_set_session_id_context(context_.get(),
+                                           reinterpret_cast<const unsigned char *>(contextId.c_str()),
+                                           contextId.length()) != 1) {
+            SWIFT_LOG(debug) << "Failed to set context-id";
+            return false;
+        }
+    }
+
+    if (options.sessionCacheTimeout) {
+        int scto = *options.sessionCacheTimeout;
+        if (scto <= 0) {
+            SWIFT_LOG(debug) << "Invalid value for session-cache-timeout";
+            return false;
+        }
+        (void)SSL_CTX_set_timeout(context_.get(), scto);
+        if (SSL_CTX_get_timeout(context_.get()) != scto) {
+            SWIFT_LOG(debug) << "Failed to set session-cache-timeout";
+            return false;
+        }
+    }
+
+    if (options.verifyCertificateCallback) {
+        verifyCertCallback = *options.verifyCertificateCallback;
+    } else {
+        verifyCertCallback = nullptr;
+    }
+
+    if (options.verifyMode) {
+        TLSOptions::VerifyMode verify_mode = *options.verifyMode;
+        int mode;
+        switch (verify_mode) {
+        case TLSOptions::VerifyMode::None:
+            mode = SSL_VERIFY_NONE;
+            break;
+        case TLSOptions::VerifyMode::Required:
+            mode = SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT | SSL_VERIFY_CLIENT_ONCE;
+            break;
+        case TLSOptions::VerifyMode::Optional:
+            mode = SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE;
+            break;
+        }
+
+        // Set up default certificate chain verification depth - may be overridden below
+        SSL_CTX_set_verify_depth(context_.get(), SSL_DEFAULT_VERIFY_DEPTH + 1);
+
+        // Set callbacks up
+        SSL_CTX_set_verify(context_.get(), mode, verifyCallback);
+
+        // Only set up certificate verification callback if a user callback has
+        // been configured via the TLSOptions
+        if (verifyCertCallback != nullptr) {
+            SSL_CTX_set_cert_verify_callback(context_.get(), certVerifyCallback, this);
+        }
+    }
+
+    if (options.verifyDepth) {
+        int depth = *options.verifyDepth;
+        if (depth <= 0) {
+            SWIFT_LOG(debug) << "Invalid value for verify-depth";
+            return false;
+        }
+
+        // Increase depth limit by one, so that verifyCallback() will log it
+        SSL_CTX_set_verify_depth(context_.get(), depth + 1);
+    }
+
+    auto updateOptionIfPresent = [this](boost::optional<bool> option, int flag) {
+        if (option) {
+            if (*option) {
+                SSL_CTX_set_options(context_.get(), flag);
+            }
+            else {
+                SSL_CTX_clear_options(context_.get(), flag);
+            }
+        }
+    };
+    updateOptionIfPresent(options.workaroundMicrosoftSessID, SSL_OP_MICROSOFT_SESS_ID_BUG);
+    updateOptionIfPresent(options.workaroundNetscapeChallenge, SSL_OP_NETSCAPE_CHALLENGE_BUG);
+    updateOptionIfPresent(options.workaroundNetscapeReuseCipherChange, SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG);
+    updateOptionIfPresent(options.workaroundSSLRef2ReuseCertType, SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG);
+    updateOptionIfPresent(options.workaroundMicrosoftBigSSLv3Buffer, SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER);
+    updateOptionIfPresent(options.workaroundSSLeay080ClientDH, SSL_OP_SSLEAY_080_CLIENT_DH_BUG);
+    updateOptionIfPresent(options.workaroundTLSD5, SSL_OP_TLS_D5_BUG);
+    updateOptionIfPresent(options.workaroundTLSBlockPadding, SSL_OP_TLS_BLOCK_PADDING_BUG);
+    updateOptionIfPresent(options.workaroundDontInsertEmptyFragments, SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS);
+    updateOptionIfPresent(options.workaroundAll, SSL_OP_ALL);
+    updateOptionIfPresent(options.suppressSSLv2, SSL_OP_NO_SSLv2);
+    updateOptionIfPresent(options.suppressSSLv3, SSL_OP_NO_SSLv3);
+    updateOptionIfPresent(options.suppressTLSv1, SSL_OP_NO_TLSv1);
+    updateOptionIfPresent(options.disableTLSRollBackBug, SSL_OP_TLS_ROLLBACK_BUG);
+    updateOptionIfPresent(options.singleDHUse, SSL_OP_SINGLE_DH_USE);
+
+    if (options.trustAnchors) {
+        // Add any additional Trust Anchors which are present in the TLSOptions
+        X509_STORE* store = SSL_CTX_get_cert_store(context_.get());
+
+        if (store) {
+            for (auto& certificate : *options.trustAnchors) {
+                auto openSSLCert = dynamic_cast<OpenSSLCertificate*>(certificate.get());
+                if (openSSLCert && openSSLCert->getInternalX509()) {
+                    X509_STORE_add_cert(store, openSSLCert->getInternalX509().get());
+                    // Don't need to increment reference count as X509_STORE_add_cert does thiS
+                }
+            }
+        }
+    }
+
+    return true;
+}
+
+
 void OpenSSLContext::accept() {
     assert(mode_ == Mode::Server);
     handle_ = std::unique_ptr<SSL>(SSL_new(context_.get()));
@@ -342,9 +591,9 @@ void OpenSSLContext::sendPendingDataToApplication() {
     }
 }
 
-bool OpenSSLContext::setCertificateChain(std::vector<std::unique_ptr<Certificate>>&& certificateChain) {
+bool OpenSSLContext::setCertificateChain(const std::vector<std::shared_ptr<Certificate>>& certificateChain) {
     if (certificateChain.size() == 0) {
-        SWIFT_LOG(warning) << "Trying to load empty certificate chain." << std::endl;
+        SWIFT_LOG(debug) << "Trying to load empty certificate chain.";
         return false;
     }
 
@@ -354,6 +603,7 @@ bool OpenSSLContext::setCertificateChain(std::vector<std::unique_ptr<Certificate
         return false;
     }
 
+    // This increments the reference count on the X509 certificate automatically
     if (SSL_CTX_use_certificate(context_.get(), openSSLCert->getInternalX509().get()) != 1) {
         return false;
     }
@@ -364,11 +614,13 @@ bool OpenSSLContext::setCertificateChain(std::vector<std::unique_ptr<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;
+                SWIFT_LOG(debug) << "Trying to load empty certificate chain.";
                 return false;
             }
-            certificate->release();
+            // Have to manually increment reference count as SSL_CTX_add_extra_chain_cert does not do so
+            openSSLCert->incrementReferenceCount();
         }
     }
 
@@ -414,16 +666,17 @@ bool OpenSSLContext::setPrivateKey(const PrivateKey::ref& privateKey) {
         safePassword.push_back(0);
         password = safePassword.data();
     }
-    auto resultKey = PEM_read_bio_PrivateKey(bio.get(), nullptr, empty_or_preset_password_cb, password);
+    // Make sure resultKey is tidied up by wrapping it in a shared_ptr
+    auto resultKey = std::shared_ptr<EVP_PKEY>(PEM_read_bio_PrivateKey(bio.get(), nullptr, empty_or_preset_password_cb, password), EVP_PKEY_free);
     if (resultKey) {
         if (handle_) {
-            auto result = SSL_use_PrivateKey(handle_.get(), resultKey);;
+            auto result = SSL_use_PrivateKey(handle_.get(), resultKey.get());
             if (result != 1) {
                 return false;
             }
         }
         else {
-            auto result = SSL_CTX_use_PrivateKey(context_.get(), resultKey);
+            auto result = SSL_CTX_use_PrivateKey(context_.get(), resultKey.get());
             if (result != 1) {
                 return false;
             }
@@ -486,7 +739,7 @@ bool OpenSSLContext::setDiffieHellmanParameters(const ByteArray& parametersInOpe
     if (bio) {
         BIO_write(bio.get(), vecptr(parametersInOpenSslDer), parametersInOpenSslDer.size());
         auto result = 0L;
-        if (auto dhparams = d2i_DHparams_bio(bio.get(), NULL)) {
+        if (auto dhparams = d2i_DHparams_bio(bio.get(), nullptr)) {
             if (handle_) {
                 result = SSL_set_tmp_dh(handle_.get(), dhparams);
             }
@@ -502,13 +755,33 @@ bool OpenSSLContext::setDiffieHellmanParameters(const ByteArray& parametersInOpe
 
 std::vector<Certificate::ref> OpenSSLContext::getPeerCertificateChain() const {
     std::vector<Certificate::ref> result;
+
+    // When this context is a server, the peer (client) certificate
+    // is obtained via SSL_get_peer_certificate, and any other
+    // certificates set by the peer are available via SSL_get_peer_cert_chain.
+    // When this context is a client, all of the server's certificates are
+    // obtained using SSL_get_peer_cert_chain
+    if (mode_ == Mode::Server) {
+        auto cert = SSL_get_peer_certificate(handle_.get());
+        if (cert) {
+            // Do not need to copy the returned cert as SSL_get_peer_certificate
+            // increments the reference count on the certificate
+            std::shared_ptr<X509> x509Cert(cert, X509_free);
+            Certificate::ref cert = std::make_shared<OpenSSLCertificate>(x509Cert);
+            result.push_back(cert);
+        }
+    }
+
     STACK_OF(X509)* chain = SSL_get_peer_cert_chain(handle_.get());
     for (int i = 0; i < sk_X509_num(chain); ++i) {
+        // Here we do need to copy the returned cert, since SSL_get_peer_cert_chain
+        // does not increment the reference count on each certificate
         std::shared_ptr<X509> x509Cert(X509_dup(sk_X509_value(chain, i)), X509_free);
 
         Certificate::ref cert = std::make_shared<OpenSSLCertificate>(x509Cert);
         result.push_back(cert);
     }
+
     return result;
 }
 
diff --git a/Swiften/TLS/OpenSSL/OpenSSLContext.h b/Swiften/TLS/OpenSSL/OpenSSLContext.h
index c18a6f4..8eb5758 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLContext.h
+++ b/Swiften/TLS/OpenSSL/OpenSSLContext.h
@@ -16,6 +16,7 @@
 #include <Swiften/Base/ByteArray.h>
 #include <Swiften/TLS/CertificateWithKey.h>
 #include <Swiften/TLS/TLSContext.h>
+#include <Swiften/TLS/TLSOptions.h>
 
 namespace std {
     template<>
@@ -38,14 +39,14 @@ namespace std {
 namespace Swift {
     class OpenSSLContext : public TLSContext, boost::noncopyable {
         public:
-            OpenSSLContext(Mode mode);
+            OpenSSLContext(const TLSOptions& options, Mode mode);
             virtual ~OpenSSLContext() override final;
 
             void accept() override final;
             void connect() override final;
             void connect(const std::string& requestHostname) override final;
 
-            bool setCertificateChain(std::vector<std::unique_ptr<Certificate>>&& certificateChain) override final;
+            bool setCertificateChain(const std::vector<std::shared_ptr<Certificate>>& certificateChain) override final;
             bool setPrivateKey(const PrivateKey::ref& privateKey) override final;
             bool setClientCertificate(CertificateWithKey::ref cert) override final;
             void setAbortTLSHandshake(bool abort) override final;
@@ -60,7 +61,11 @@ namespace Swift {
             virtual ByteArray getFinishMessage() const override final;
             virtual ByteArray getPeerFinishMessage() const override final;
 
+            void setX509StoreContext(X509_STORE_CTX *ptr) { x509_store_ctx = ptr; }
+            std::function<int (const TLSContext *)> getVerifyCertCallback() { return verifyCertCallback; }
+
         private:
+            bool configure(const TLSOptions& options);
             static void ensureLibraryInitialized();
             static int handleServerNameCallback(SSL *ssl, int *ad, void *arg);
             static CertificateVerificationError::Type getVerificationErrorTypeForResult(int);
@@ -81,5 +86,7 @@ namespace Swift {
             BIO* readBIO_ = nullptr;
             BIO* writeBIO_ = nullptr;
             bool abortTLSHandshake_ = false;
-    };
+            X509_STORE_CTX *x509_store_ctx = nullptr;
+            std::function<int (const TLSContext *)> verifyCertCallback = nullptr;
+   };
 }
diff --git a/Swiften/TLS/OpenSSL/OpenSSLContextFactory.cpp b/Swiften/TLS/OpenSSL/OpenSSLContextFactory.cpp
index a9ba5ab..e332ca8 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLContextFactory.cpp
+++ b/Swiften/TLS/OpenSSL/OpenSSLContextFactory.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2018 Isode Limited.
+ * Copyright (c) 2010-2019 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */
@@ -21,8 +21,8 @@ bool OpenSSLContextFactory::canCreate() const {
     return true;
 }
 
-std::unique_ptr<TLSContext> OpenSSLContextFactory::createTLSContext(const TLSOptions&, TLSContext::Mode mode) {
-    return std::unique_ptr<TLSContext>(new OpenSSLContext(mode));
+std::unique_ptr<TLSContext> OpenSSLContextFactory::createTLSContext(const TLSOptions& options, TLSContext::Mode mode) {
+    return std::make_unique<OpenSSLContext>(options, mode);
 }
 
 ByteArray OpenSSLContextFactory::convertDHParametersFromPEMToDER(const std::string& dhParametersInPEM) {
@@ -47,14 +47,14 @@ ByteArray OpenSSLContextFactory::convertDHParametersFromPEMToDER(const std::stri
 
 void OpenSSLContextFactory::setCheckCertificateRevocation(bool check) {
     if (check) {
-        SWIFT_LOG(warning) << "CRL Checking not supported for OpenSSL" << std::endl;
+        SWIFT_LOG(warning) << "CRL Checking not supported for OpenSSL";
         assert(false);
     }
 }
 
 void OpenSSLContextFactory::setDisconnectOnCardRemoval(bool check) {
     if (check) {
-        SWIFT_LOG(warning) << "Smart cards not supported for OpenSSL" << std::endl;
+        SWIFT_LOG(warning) << "Smart cards not supported for OpenSSL";
     }
 }
 
diff --git a/Swiften/TLS/OpenSSL/OpenSSLContextFactory.h b/Swiften/TLS/OpenSSL/OpenSSLContextFactory.h
index 95a2b0c..834e479 100644
--- a/Swiften/TLS/OpenSSL/OpenSSLContextFactory.h
+++ b/Swiften/TLS/OpenSSL/OpenSSLContextFactory.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2018 Isode Limited.
+ * Copyright (c) 2010-2019 Isode Limited.
  * All rights reserved.
  * See the COPYING file for more information.
  */