rtc_base/openssl_utility.cc

/*
 *  Copyright 2018 The WebRTC Project Authors. All rights reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "rtc_base/openssl_utility.h"
#if defined(WEBRTC_WIN)
// Must be included first before openssl headers.
#include "rtc_base/win32.h"  // NOLINT
#endif                       // WEBRTC_WIN

#include <openssl/err.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <stddef.h>

#include "rtc_base/arraysize.h"
#include "rtc_base/logging.h"
#include "rtc_base/numerics/safe_conversions.h"
#include "rtc_base/openssl.h"
#include "rtc_base/openssl_certificate.h"
#ifndef WEBRTC_EXCLUDE_BUILT_IN_SSL_ROOT_CERTS
#include "rtc_base/ssl_roots.h"
#endif  // WEBRTC_EXCLUDE_BUILT_IN_SSL_ROOT_CERTS

namespace rtc {
namespace openssl {

// Holds various helper methods.
namespace {
void LogCertificates(SSL* ssl, X509* certificate) {
// Logging certificates is extremely verbose. So it is disabled by default.
#ifdef LOG_CERTIFICATES
  BIO* mem = BIO_new(BIO_s_mem());
  if (mem == nullptr) {
    RTC_DLOG(LS_ERROR) << "BIO_new() failed to allocate memory.";
    return;
  }

  RTC_DLOG(LS_INFO) << "Certificate from server:";
  X509_print_ex(mem, certificate, XN_FLAG_SEP_CPLUS_SPC, X509_FLAG_NO_HEADER);
  BIO_write(mem, "\0", 1);

  char* buffer = nullptr;
  BIO_get_mem_data(mem, &buffer);
  if (buffer != nullptr) {
    RTC_DLOG(LS_INFO) << buffer;
  } else {
    RTC_DLOG(LS_ERROR) << "BIO_get_mem_data() failed to get buffer.";
  }
  BIO_free(mem);

  const char* cipher_name = SSL_CIPHER_get_name(SSL_get_current_cipher(ssl));
  if (cipher_name != nullptr) {
    RTC_DLOG(LS_INFO) << "Cipher: " << cipher_name;
  } else {
    RTC_DLOG(LS_ERROR) << "SSL_CIPHER_DESCRIPTION() failed to get cipher_name.";
  }
#endif
}
}  // namespace

bool VerifyPeerCertMatchesHost(SSL* ssl, const std::string& host) {
  if (host.empty()) {
    RTC_DLOG(LS_ERROR) << "Hostname is empty. Cannot verify peer certificate.";
    return false;
  }

  if (ssl == nullptr) {
    RTC_DLOG(LS_ERROR) << "SSL is nullptr. Cannot verify peer certificate.";
    return false;
  }

  X509* certificate = SSL_get_peer_certificate(ssl);
  if (certificate == nullptr) {
    RTC_DLOG(LS_ERROR)
        << "SSL_get_peer_certificate failed. This should never happen.";
    return false;
  }

  LogCertificates(ssl, certificate);

  bool is_valid_cert_name =
      X509_check_host(certificate, host.c_str(), host.size(), 0, nullptr) == 1;
  X509_free(certificate);
  return is_valid_cert_name;
}

void LogSSLErrors(const std::string& prefix) {
  char error_buf[200];
  unsigned long err;  // NOLINT

  while ((err = ERR_get_error()) != 0) {
    ERR_error_string_n(err, error_buf, sizeof(error_buf));
    RTC_LOG(LS_ERROR) << prefix << ": " << error_buf << "\n";
  }
}

#ifndef WEBRTC_EXCLUDE_BUILT_IN_SSL_ROOT_CERTS
bool LoadBuiltinSSLRootCertificates(SSL_CTX* ctx) {
  int count_of_added_certs = 0;
  for (size_t i = 0; i < arraysize(kSSLCertCertificateList); i++) {
    const unsigned char* cert_buffer = kSSLCertCertificateList[i];
    size_t cert_buffer_len = kSSLCertCertificateSizeList[i];
    X509* cert = d2i_X509(nullptr, &cert_buffer,
                          checked_cast<long>(cert_buffer_len));  // NOLINT
    if (cert) {
      int return_value = X509_STORE_add_cert(SSL_CTX_get_cert_store(ctx), cert);
      if (return_value == 0) {
        RTC_LOG(LS_WARNING) << "Unable to add certificate.";
      } else {
        count_of_added_certs++;
      }
      X509_free(cert);
    }
  }
  return count_of_added_certs > 0;
}
#endif  // WEBRTC_EXCLUDE_BUILT_IN_SSL_ROOT_CERTS

}  // namespace openssl
}  // namespace rtc