1 files changed, 59 insertions, 0 deletions
diff --git a/util/crypto/openssl_util.cc b/util/crypto/openssl_util.cc
new file mode 100644
index 00000000..92253b42
--- /dev/null
+++ b/util/crypto/openssl_util.cc
@@ -0,0 +1,59 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "util/crypto/openssl_util.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <string>
+
+#include "absl/strings/string_view.h"
+#include "openssl/crypto.h"
+#include "openssl/err.h"
+#include "openssl/ssl.h"
+#include "platform/api/logging.h"
+
+namespace openscreen {
+
+namespace {
+
+// Callback routine for OpenSSL to print error messages. |str| is a
+// nullptr-terminated string of length |len| containing diagnostic information
+// such as the library, function and reason for the error, the file and line
+// where the error originated, plus potentially any context-specific
+// information about the error. |context| contains a pointer to user-supplied
+// data, which is currently unused.
+// If this callback returns a value <= 0, OpenSSL will stop processing the
+// error queue and return, otherwise it will continue calling this function
+// until all errors have been removed from the queue.
+int OpenSSLErrorCallback(const char* str, size_t len, void* context) {
+  OSP_DVLOG << "\t" << absl::string_view(str, len);
+  return 1;
+}
+
+}  // namespace
+
+void EnsureOpenSSLInit() {
+  OPENSSL_init_ssl(OPENSSL_INIT_LOAD_SSL_STRINGS, nullptr);
+}
+
+void EnsureOpenSSLCleanup() {
+  EVP_cleanup();
+}
+
+void ClearOpenSSLERRStack(const Location& location) {
+  if (OSP_DCHECK_IS_ON()) {
+    uint32_t error_num = ERR_peek_error();
+    if (error_num == 0)
+      return;
+
+    OSP_DVLOG << "OpenSSL ERR_get_error stack from " << location.ToString();
+    ERR_print_errors_cb(&OpenSSLErrorCallback, nullptr);
+  } else {
+    ERR_clear_error();
+  }
+}
+
+}  // namespace openscreen