Adding upstream version 1.52.0.upstream/1.52.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2692 insertions, 0 deletions

diff --git a/src/shrpx_tls.cc b/src/shrpx_tls.cc
new file mode 100644
index 0000000..24216a7
--- /dev/null
+++ b/src/shrpx_tls.cc
@@ -0,0 +1,2692 @@
+/*
+ * nghttp2 - HTTP/2 C Library
+ *
+ * Copyright (c) 2012 Tatsuhiro Tsujikawa
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "shrpx_tls.h"
+
+#ifdef HAVE_SYS_SOCKET_H
+#  include <sys/socket.h>
+#endif // HAVE_SYS_SOCKET_H
+#ifdef HAVE_NETDB_H
+#  include <netdb.h>
+#endif // HAVE_NETDB_H
+#include <netinet/tcp.h>
+#include <pthread.h>
+#include <sys/types.h>
+
+#include <vector>
+#include <string>
+#include <iomanip>
+
+#include <iostream>
+
+#include "ssl_compat.h"
+
+#include <openssl/crypto.h>
+#include <openssl/x509.h>
+#include <openssl/x509v3.h>
+#include <openssl/rand.h>
+#include <openssl/dh.h>
+#ifndef OPENSSL_NO_OCSP
+#  include <openssl/ocsp.h>
+#endif // OPENSSL_NO_OCSP
+#if OPENSSL_3_0_0_API
+#  include <openssl/params.h>
+#  include <openssl/core_names.h>
+#  include <openssl/decoder.h>
+#endif // OPENSSL_3_0_0_API
+#ifdef OPENSSL_IS_BORINGSSL
+#  include <openssl/hmac.h>
+#endif // OPENSSL_IS_BORINGSSL
+
+#include <nghttp2/nghttp2.h>
+
+#ifdef ENABLE_HTTP3
+#  include <ngtcp2/ngtcp2.h>
+#  include <ngtcp2/ngtcp2_crypto.h>
+#  ifdef HAVE_LIBNGTCP2_CRYPTO_OPENSSL
+#    include <ngtcp2/ngtcp2_crypto_openssl.h>
+#  endif // HAVE_LIBNGTCP2_CRYPTO_OPENSSL
+#  ifdef HAVE_LIBNGTCP2_CRYPTO_BORINGSSL
+#    include <ngtcp2/ngtcp2_crypto_boringssl.h>
+#  endif // HAVE_LIBNGTCP2_CRYPTO_BORINGSSL
+#endif   // ENABLE_HTTP3
+
+#include "shrpx_log.h"
+#include "shrpx_client_handler.h"
+#include "shrpx_config.h"
+#include "shrpx_worker.h"
+#include "shrpx_downstream_connection_pool.h"
+#include "shrpx_http2_session.h"
+#include "shrpx_memcached_request.h"
+#include "shrpx_memcached_dispatcher.h"
+#include "shrpx_connection_handler.h"
+#ifdef ENABLE_HTTP3
+#  include "shrpx_http3_upstream.h"
+#endif // ENABLE_HTTP3
+#include "util.h"
+#include "tls.h"
+#include "template.h"
+#include "timegm.h"
+
+using namespace nghttp2;
+
+namespace shrpx {
+
+namespace tls {
+
+#if !OPENSSL_1_1_API
+namespace {
+const unsigned char *ASN1_STRING_get0_data(ASN1_STRING *x) {
+  return ASN1_STRING_data(x);
+}
+} // namespace
+#endif // !OPENSSL_1_1_API
+
+#ifndef OPENSSL_NO_NEXTPROTONEG
+namespace {
+int next_proto_cb(SSL *s, const unsigned char **data, unsigned int *len,
+                  void *arg) {
+  auto &prefs = get_config()->tls.alpn_prefs;
+  *data = prefs.data();
+  *len = prefs.size();
+  return SSL_TLSEXT_ERR_OK;
+}
+} // namespace
+#endif // !OPENSSL_NO_NEXTPROTONEG
+
+namespace {
+int verify_callback(int preverify_ok, X509_STORE_CTX *ctx) {
+  if (!preverify_ok) {
+    int err = X509_STORE_CTX_get_error(ctx);
+    int depth = X509_STORE_CTX_get_error_depth(ctx);
+    if (err == X509_V_ERR_CERT_HAS_EXPIRED && depth == 0 &&
+        get_config()->tls.client_verify.tolerate_expired) {
+      LOG(INFO) << "The client certificate has expired, but is accepted by "
+                   "configuration";
+      return 1;
+    }
+    LOG(ERROR) << "client certificate verify error:num=" << err << ":"
+               << X509_verify_cert_error_string(err) << ":depth=" << depth;
+  }
+  return preverify_ok;
+}
+} // namespace
+
+int set_alpn_prefs(std::vector<unsigned char> &out,
+                   const std::vector<StringRef> &protos) {
+  size_t len = 0;
+
+  for (const auto &proto : protos) {
+    if (proto.size() > 255) {
+      LOG(FATAL) << "Too long ALPN identifier: " << proto.size();
+      return -1;
+    }
+
+    len += 1 + proto.size();
+  }
+
+  if (len > (1 << 16) - 1) {
+    LOG(FATAL) << "Too long ALPN identifier list: " << len;
+    return -1;
+  }
+
+  out.resize(len);
+  auto ptr = out.data();
+
+  for (const auto &proto : protos) {
+    *ptr++ = proto.size();
+    ptr = std::copy(std::begin(proto), std::end(proto), ptr);
+  }
+
+  return 0;
+}
+
+namespace {
+int ssl_pem_passwd_cb(char *buf, int size, int rwflag, void *user_data) {
+  auto config = static_cast<Config *>(user_data);
+  auto len = static_cast<int>(config->tls.private_key_passwd.size());
+  if (size < len + 1) {
+    LOG(ERROR) << "ssl_pem_passwd_cb: buf is too small " << size;
+    return 0;
+  }
+  // Copy string including last '\0'.
+  memcpy(buf, config->tls.private_key_passwd.c_str(), len + 1);
+  return len;
+}
+} // namespace
+
+namespace {
+// *al is set to SSL_AD_UNRECOGNIZED_NAME by openssl, so we don't have
+// to set it explicitly.
+int servername_callback(SSL *ssl, int *al, void *arg) {
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  auto handler = static_cast<ClientHandler *>(conn->data);
+  auto worker = handler->get_worker();
+
+  auto rawhost = SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
+  if (rawhost == nullptr) {
+    return SSL_TLSEXT_ERR_NOACK;
+  }
+
+  auto len = strlen(rawhost);
+  // NI_MAXHOST includes terminal NULL.
+  if (len == 0 || len + 1 > NI_MAXHOST) {
+    return SSL_TLSEXT_ERR_NOACK;
+  }
+
+  std::array<uint8_t, NI_MAXHOST> buf;
+
+  auto end_buf = std::copy_n(rawhost, len, std::begin(buf));
+
+  util::inp_strlower(std::begin(buf), end_buf);
+
+  auto hostname = StringRef{std::begin(buf), end_buf};
+
+#ifdef ENABLE_HTTP3
+  auto cert_tree = conn->proto == Proto::HTTP3
+                       ? worker->get_quic_cert_lookup_tree()
+                       : worker->get_cert_lookup_tree();
+#else  // !ENABLE_HTTP3
+  auto cert_tree = worker->get_cert_lookup_tree();
+#endif // !ENABLE_HTTP3
+
+  auto idx = cert_tree->lookup(hostname);
+  if (idx == -1) {
+    return SSL_TLSEXT_ERR_NOACK;
+  }
+
+  handler->set_tls_sni(hostname);
+
+  auto conn_handler = worker->get_connection_handler();
+
+#ifdef ENABLE_HTTP3
+  const auto &ssl_ctx_list = conn->proto == Proto::HTTP3
+                                 ? conn_handler->get_quic_indexed_ssl_ctx(idx)
+                                 : conn_handler->get_indexed_ssl_ctx(idx);
+#else  // !ENABLE_HTTP3
+  const auto &ssl_ctx_list = conn_handler->get_indexed_ssl_ctx(idx);
+#endif // !ENABLE_HTTP3
+
+  assert(!ssl_ctx_list.empty());
+
+#if !defined(OPENSSL_IS_BORINGSSL) && !LIBRESSL_IN_USE &&                      \
+    OPENSSL_VERSION_NUMBER >= 0x10002000L
+  auto num_sigalgs =
+      SSL_get_sigalgs(ssl, 0, nullptr, nullptr, nullptr, nullptr, nullptr);
+
+  for (idx = 0; idx < num_sigalgs; ++idx) {
+    int signhash;
+
+    SSL_get_sigalgs(ssl, idx, nullptr, nullptr, &signhash, nullptr, nullptr);
+    switch (signhash) {
+    case NID_ecdsa_with_SHA256:
+    case NID_ecdsa_with_SHA384:
+    case NID_ecdsa_with_SHA512:
+      break;
+    default:
+      continue;
+    }
+
+    break;
+  }
+
+  if (idx == num_sigalgs) {
+    SSL_set_SSL_CTX(ssl, ssl_ctx_list[0]);
+
+    return SSL_TLSEXT_ERR_OK;
+  }
+
+  auto num_shared_curves = SSL_get_shared_curve(ssl, -1);
+
+  for (auto i = 0; i < num_shared_curves; ++i) {
+    auto shared_curve = SSL_get_shared_curve(ssl, i);
+#  if OPENSSL_3_0_0_API
+    // It looks like only short name is defined in OpenSSL.  No idea
+    // which one to use because it is unknown that which one
+    // EVP_PKEY_get_utf8_string_param("group") returns.
+    auto shared_curve_name = OBJ_nid2sn(shared_curve);
+    if (shared_curve_name == nullptr) {
+      continue;
+    }
+#  endif // OPENSSL_3_0_0_API
+
+    for (auto ssl_ctx : ssl_ctx_list) {
+      auto cert = SSL_CTX_get0_certificate(ssl_ctx);
+
+#  if OPENSSL_1_1_API
+      auto pubkey = X509_get0_pubkey(cert);
+#  else  // !OPENSSL_1_1_API
+      auto pubkey = X509_get_pubkey(cert);
+#  endif // !OPENSSL_1_1_API
+
+      if (EVP_PKEY_base_id(pubkey) != EVP_PKEY_EC) {
+        continue;
+      }
+
+#  if OPENSSL_3_0_0_API
+      std::array<char, 64> curve_name;
+      if (!EVP_PKEY_get_utf8_string_param(pubkey, "group", curve_name.data(),
+                                          curve_name.size(), nullptr)) {
+        continue;
+      }
+
+      if (strcmp(shared_curve_name, curve_name.data()) == 0) {
+        SSL_set_SSL_CTX(ssl, ssl_ctx);
+        return SSL_TLSEXT_ERR_OK;
+      }
+#  else // !OPENSSL_3_0_0_API
+#    if OPENSSL_1_1_API
+      auto eckey = EVP_PKEY_get0_EC_KEY(pubkey);
+#    else  // !OPENSSL_1_1_API
+      auto eckey = EVP_PKEY_get1_EC_KEY(pubkey);
+#    endif // !OPENSSL_1_1_API
+
+      if (eckey == nullptr) {
+        continue;
+      }
+
+      auto ecgroup = EC_KEY_get0_group(eckey);
+      auto cert_curve = EC_GROUP_get_curve_name(ecgroup);
+
+#    if !OPENSSL_1_1_API
+      EC_KEY_free(eckey);
+      EVP_PKEY_free(pubkey);
+#    endif // !OPENSSL_1_1_API
+
+      if (shared_curve == cert_curve) {
+        SSL_set_SSL_CTX(ssl, ssl_ctx);
+        return SSL_TLSEXT_ERR_OK;
+      }
+#  endif   // !OPENSSL_3_0_0_API
+    }
+  }
+#endif // !defined(OPENSSL_IS_BORINGSSL) && !LIBRESSL_IN_USE &&
+       // OPENSSL_VERSION_NUMBER >= 0x10002000L
+
+  SSL_set_SSL_CTX(ssl, ssl_ctx_list[0]);
+
+  return SSL_TLSEXT_ERR_OK;
+}
+} // namespace
+
+#ifndef OPENSSL_IS_BORINGSSL
+namespace {
+std::shared_ptr<std::vector<uint8_t>>
+get_ocsp_data(TLSContextData *tls_ctx_data) {
+#  ifdef HAVE_ATOMIC_STD_SHARED_PTR
+  return std::atomic_load_explicit(&tls_ctx_data->ocsp_data,
+                                   std::memory_order_acquire);
+#  else  // !HAVE_ATOMIC_STD_SHARED_PTR
+  std::lock_guard<std::mutex> g(tls_ctx_data->mu);
+  return tls_ctx_data->ocsp_data;
+#  endif // !HAVE_ATOMIC_STD_SHARED_PTR
+}
+} // namespace
+
+namespace {
+int ocsp_resp_cb(SSL *ssl, void *arg) {
+  auto ssl_ctx = SSL_get_SSL_CTX(ssl);
+  auto tls_ctx_data =
+      static_cast<TLSContextData *>(SSL_CTX_get_app_data(ssl_ctx));
+
+  auto data = get_ocsp_data(tls_ctx_data);
+
+  if (!data) {
+    return SSL_TLSEXT_ERR_OK;
+  }
+
+  auto buf =
+      static_cast<uint8_t *>(CRYPTO_malloc(data->size(), __FILE__, __LINE__));
+
+  if (!buf) {
+    return SSL_TLSEXT_ERR_OK;
+  }
+
+  std::copy(std::begin(*data), std::end(*data), buf);
+
+  SSL_set_tlsext_status_ocsp_resp(ssl, buf, data->size());
+
+  return SSL_TLSEXT_ERR_OK;
+}
+} // namespace
+#endif // OPENSSL_IS_BORINGSSL
+
+constexpr auto MEMCACHED_SESSION_CACHE_KEY_PREFIX =
+    StringRef::from_lit("nghttpx:tls-session-cache:");
+
+namespace {
+int tls_session_client_new_cb(SSL *ssl, SSL_SESSION *session) {
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  if (conn->tls.client_session_cache == nullptr) {
+    return 0;
+  }
+
+  try_cache_tls_session(conn->tls.client_session_cache, session,
+                        ev_now(conn->loop));
+
+  return 0;
+}
+} // namespace
+
+namespace {
+int tls_session_new_cb(SSL *ssl, SSL_SESSION *session) {
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  auto handler = static_cast<ClientHandler *>(conn->data);
+  auto worker = handler->get_worker();
+  auto dispatcher = worker->get_session_cache_memcached_dispatcher();
+  auto &balloc = handler->get_block_allocator();
+
+#ifdef TLS1_3_VERSION
+  if (SSL_version(ssl) == TLS1_3_VERSION) {
+    return 0;
+  }
+#endif // TLS1_3_VERSION
+
+  const unsigned char *id;
+  unsigned int idlen;
+
+  id = SSL_SESSION_get_id(session, &idlen);
+
+  if (LOG_ENABLED(INFO)) {
+    LOG(INFO) << "Memcached: cache session, id=" << util::format_hex(id, idlen);
+  }
+
+  auto req = std::make_unique<MemcachedRequest>();
+  req->op = MemcachedOp::ADD;
+  req->key = MEMCACHED_SESSION_CACHE_KEY_PREFIX.str();
+  req->key +=
+      util::format_hex(balloc, StringRef{id, static_cast<size_t>(idlen)});
+
+  auto sessionlen = i2d_SSL_SESSION(session, nullptr);
+  req->value.resize(sessionlen);
+  auto buf = &req->value[0];
+  i2d_SSL_SESSION(session, &buf);
+  req->expiry = 12_h;
+  req->cb = [](MemcachedRequest *req, MemcachedResult res) {
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "Memcached: session cache done.  key=" << req->key
+                << ", status_code=" << static_cast<uint16_t>(res.status_code)
+                << ", value="
+                << std::string(std::begin(res.value), std::end(res.value));
+    }
+    if (res.status_code != MemcachedStatusCode::NO_ERROR) {
+      LOG(WARN) << "Memcached: failed to cache session key=" << req->key
+                << ", status_code=" << static_cast<uint16_t>(res.status_code)
+                << ", value="
+                << std::string(std::begin(res.value), std::end(res.value));
+    }
+  };
+  assert(!req->canceled);
+
+  dispatcher->add_request(std::move(req));
+
+  return 0;
+}
+} // namespace
+
+namespace {
+SSL_SESSION *tls_session_get_cb(SSL *ssl,
+#if OPENSSL_1_1_API || LIBRESSL_2_7_API
+                                const unsigned char *id,
+#else  // !(OPENSSL_1_1_API || LIBRESSL_2_7_API)
+                                unsigned char *id,
+#endif // !(OPENSSL_1_1_API || LIBRESSL_2_7_API)
+                                int idlen, int *copy) {
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  auto handler = static_cast<ClientHandler *>(conn->data);
+  auto worker = handler->get_worker();
+  auto dispatcher = worker->get_session_cache_memcached_dispatcher();
+  auto &balloc = handler->get_block_allocator();
+
+  if (idlen == 0) {
+    return nullptr;
+  }
+
+  if (conn->tls.cached_session) {
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "Memcached: found cached session, id="
+                << util::format_hex(id, idlen);
+    }
+
+    // This is required, without this, memory leak occurs.
+    *copy = 0;
+
+    auto session = conn->tls.cached_session;
+    conn->tls.cached_session = nullptr;
+    return session;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    LOG(INFO) << "Memcached: get cached session, id="
+              << util::format_hex(id, idlen);
+  }
+
+  auto req = std::make_unique<MemcachedRequest>();
+  req->op = MemcachedOp::GET;
+  req->key = MEMCACHED_SESSION_CACHE_KEY_PREFIX.str();
+  req->key +=
+      util::format_hex(balloc, StringRef{id, static_cast<size_t>(idlen)});
+  req->cb = [conn](MemcachedRequest *, MemcachedResult res) {
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "Memcached: returned status code "
+                << static_cast<uint16_t>(res.status_code);
+    }
+
+    // We might stop reading, so start it again
+    conn->rlimit.startw();
+    ev_timer_again(conn->loop, &conn->rt);
+
+    conn->wlimit.startw();
+    ev_timer_again(conn->loop, &conn->wt);
+
+    conn->tls.cached_session_lookup_req = nullptr;
+    if (res.status_code != MemcachedStatusCode::NO_ERROR) {
+      conn->tls.handshake_state = TLSHandshakeState::CANCEL_SESSION_CACHE;
+      return;
+    }
+
+    const uint8_t *p = res.value.data();
+
+    auto session = d2i_SSL_SESSION(nullptr, &p, res.value.size());
+    if (!session) {
+      if (LOG_ENABLED(INFO)) {
+        LOG(INFO) << "cannot materialize session";
+      }
+      conn->tls.handshake_state = TLSHandshakeState::CANCEL_SESSION_CACHE;
+      return;
+    }
+
+    conn->tls.cached_session = session;
+    conn->tls.handshake_state = TLSHandshakeState::GOT_SESSION_CACHE;
+  };
+
+  conn->tls.handshake_state = TLSHandshakeState::WAIT_FOR_SESSION_CACHE;
+  conn->tls.cached_session_lookup_req = req.get();
+
+  dispatcher->add_request(std::move(req));
+
+  return nullptr;
+}
+} // namespace
+
+namespace {
+int ticket_key_cb(SSL *ssl, unsigned char *key_name, unsigned char *iv,
+                  EVP_CIPHER_CTX *ctx,
+#if OPENSSL_3_0_0_API
+                  EVP_MAC_CTX *hctx,
+#else  // !OPENSSL_3_0_0_API
+                  HMAC_CTX *hctx,
+#endif // !OPENSSL_3_0_0_API
+                  int enc) {
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  auto handler = static_cast<ClientHandler *>(conn->data);
+  auto worker = handler->get_worker();
+  auto ticket_keys = worker->get_ticket_keys();
+
+  if (!ticket_keys) {
+    // No ticket keys available.
+    return -1;
+  }
+
+  auto &keys = ticket_keys->keys;
+  assert(!keys.empty());
+
+  if (enc) {
+    if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) == 0) {
+      if (LOG_ENABLED(INFO)) {
+        CLOG(INFO, handler) << "session ticket key: RAND_bytes failed";
+      }
+      return -1;
+    }
+
+    auto &key = keys[0];
+
+    if (LOG_ENABLED(INFO)) {
+      CLOG(INFO, handler) << "encrypt session ticket key: "
+                          << util::format_hex(key.data.name);
+    }
+
+    std::copy(std::begin(key.data.name), std::end(key.data.name), key_name);
+
+    EVP_EncryptInit_ex(ctx, get_config()->tls.ticket.cipher, nullptr,
+                       key.data.enc_key.data(), iv);
+#if OPENSSL_3_0_0_API
+    std::array<OSSL_PARAM, 3> params{
+        OSSL_PARAM_construct_octet_string(
+            OSSL_MAC_PARAM_KEY, key.data.hmac_key.data(), key.hmac_keylen),
+        OSSL_PARAM_construct_utf8_string(
+            OSSL_MAC_PARAM_DIGEST,
+            const_cast<char *>(EVP_MD_get0_name(key.hmac)), 0),
+        OSSL_PARAM_construct_end(),
+    };
+    if (!EVP_MAC_CTX_set_params(hctx, params.data())) {
+      if (LOG_ENABLED(INFO)) {
+        CLOG(INFO, handler) << "EVP_MAC_CTX_set_params failed";
+      }
+      return -1;
+    }
+#else  // !OPENSSL_3_0_0_API
+    HMAC_Init_ex(hctx, key.data.hmac_key.data(), key.hmac_keylen, key.hmac,
+                 nullptr);
+#endif // !OPENSSL_3_0_0_API
+    return 1;
+  }
+
+  size_t i;
+  for (i = 0; i < keys.size(); ++i) {
+    auto &key = keys[i];
+    if (std::equal(std::begin(key.data.name), std::end(key.data.name),
+                   key_name)) {
+      break;
+    }
+  }
+
+  if (i == keys.size()) {
+    if (LOG_ENABLED(INFO)) {
+      CLOG(INFO, handler) << "session ticket key "
+                          << util::format_hex(key_name, 16) << " not found";
+    }
+    return 0;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    CLOG(INFO, handler) << "decrypt session ticket key: "
+                        << util::format_hex(key_name, 16);
+  }
+
+  auto &key = keys[i];
+#if OPENSSL_3_0_0_API
+  std::array<OSSL_PARAM, 3> params{
+      OSSL_PARAM_construct_octet_string(
+          OSSL_MAC_PARAM_KEY, key.data.hmac_key.data(), key.hmac_keylen),
+      OSSL_PARAM_construct_utf8_string(
+          OSSL_MAC_PARAM_DIGEST, const_cast<char *>(EVP_MD_get0_name(key.hmac)),
+          0),
+      OSSL_PARAM_construct_end(),
+  };
+  if (!EVP_MAC_CTX_set_params(hctx, params.data())) {
+    if (LOG_ENABLED(INFO)) {
+      CLOG(INFO, handler) << "EVP_MAC_CTX_set_params failed";
+    }
+    return -1;
+  }
+#else  // !OPENSSL_3_0_0_API
+  HMAC_Init_ex(hctx, key.data.hmac_key.data(), key.hmac_keylen, key.hmac,
+               nullptr);
+#endif // !OPENSSL_3_0_0_API
+  EVP_DecryptInit_ex(ctx, key.cipher, nullptr, key.data.enc_key.data(), iv);
+
+#ifdef TLS1_3_VERSION
+  // If ticket_key_cb is not set, OpenSSL always renew ticket for
+  // TLSv1.3.
+  if (SSL_version(ssl) == TLS1_3_VERSION) {
+    return 2;
+  }
+#endif // TLS1_3_VERSION
+
+  return i == 0 ? 1 : 2;
+}
+} // namespace
+
+namespace {
+void info_callback(const SSL *ssl, int where, int ret) {
+#ifdef TLS1_3_VERSION
+  // TLSv1.3 has no renegotiation.
+  if (SSL_version(ssl) == TLS1_3_VERSION) {
+    return;
+  }
+#endif // TLS1_3_VERSION
+
+  // To mitigate possible DOS attack using lots of renegotiations, we
+  // disable renegotiation. Since OpenSSL does not provide an easy way
+  // to disable it, we check that renegotiation is started in this
+  // callback.
+  if (where & SSL_CB_HANDSHAKE_START) {
+    auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+    if (conn && conn->tls.initial_handshake_done) {
+      auto handler = static_cast<ClientHandler *>(conn->data);
+      if (LOG_ENABLED(INFO)) {
+        CLOG(INFO, handler) << "TLS renegotiation started";
+      }
+      handler->start_immediate_shutdown();
+    }
+  }
+}
+} // namespace
+
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+namespace {
+int alpn_select_proto_cb(SSL *ssl, const unsigned char **out,
+                         unsigned char *outlen, const unsigned char *in,
+                         unsigned int inlen, void *arg) {
+  // We assume that get_config()->npn_list contains ALPN protocol
+  // identifier sorted by preference order.  So we just break when we
+  // found the first overlap.
+  for (const auto &target_proto_id : get_config()->tls.npn_list) {
+    for (auto p = in, end = in + inlen; p < end;) {
+      auto proto_id = p + 1;
+      auto proto_len = *p;
+
+      if (proto_id + proto_len <= end &&
+          util::streq(target_proto_id, StringRef{proto_id, proto_len})) {
+
+        *out = reinterpret_cast<const unsigned char *>(proto_id);
+        *outlen = proto_len;
+
+        return SSL_TLSEXT_ERR_OK;
+      }
+
+      p += 1 + proto_len;
+    }
+  }
+
+  return SSL_TLSEXT_ERR_NOACK;
+}
+} // namespace
+#endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+
+#ifdef ENABLE_HTTP3
+#  if OPENSSL_VERSION_NUMBER >= 0x10002000L
+namespace {
+int quic_alpn_select_proto_cb(SSL *ssl, const unsigned char **out,
+                              unsigned char *outlen, const unsigned char *in,
+                              unsigned int inlen, void *arg) {
+  constexpr StringRef alpnlist[] = {
+      StringRef::from_lit("h3"),
+      StringRef::from_lit("h3-29"),
+  };
+
+  for (auto &alpn : alpnlist) {
+    for (auto p = in, end = in + inlen; p < end;) {
+      auto proto_id = p + 1;
+      auto proto_len = *p;
+
+      if (alpn.size() == proto_len &&
+          memcmp(alpn.byte(), proto_id, alpn.size()) == 0) {
+        *out = proto_id;
+        *outlen = proto_len;
+
+        return SSL_TLSEXT_ERR_OK;
+      }
+
+      p += 1 + proto_len;
+    }
+  }
+
+  return SSL_TLSEXT_ERR_ALERT_FATAL;
+}
+} // namespace
+#  endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+#endif   // ENABLE_HTTP3
+
+#if !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L &&               \
+    !defined(OPENSSL_IS_BORINGSSL)
+
+#  ifndef TLSEXT_TYPE_signed_certificate_timestamp
+#    define TLSEXT_TYPE_signed_certificate_timestamp 18
+#  endif // !TLSEXT_TYPE_signed_certificate_timestamp
+
+namespace {
+int sct_add_cb(SSL *ssl, unsigned int ext_type, unsigned int context,
+               const unsigned char **out, size_t *outlen, X509 *x,
+               size_t chainidx, int *al, void *add_arg) {
+  assert(ext_type == TLSEXT_TYPE_signed_certificate_timestamp);
+
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  if (!conn->tls.sct_requested) {
+    return 0;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    LOG(INFO) << "sct_add_cb is called, chainidx=" << chainidx << ", x=" << x
+              << ", context=" << log::hex << context;
+  }
+
+  // We only have SCTs for leaf certificate.
+  if (chainidx != 0) {
+    return 0;
+  }
+
+  auto ssl_ctx = SSL_get_SSL_CTX(ssl);
+  auto tls_ctx_data =
+      static_cast<TLSContextData *>(SSL_CTX_get_app_data(ssl_ctx));
+
+  *out = tls_ctx_data->sct_data.data();
+  *outlen = tls_ctx_data->sct_data.size();
+
+  return 1;
+}
+} // namespace
+
+namespace {
+void sct_free_cb(SSL *ssl, unsigned int ext_type, unsigned int context,
+                 const unsigned char *out, void *add_arg) {
+  assert(ext_type == TLSEXT_TYPE_signed_certificate_timestamp);
+}
+} // namespace
+
+namespace {
+int sct_parse_cb(SSL *ssl, unsigned int ext_type, unsigned int context,
+                 const unsigned char *in, size_t inlen, X509 *x,
+                 size_t chainidx, int *al, void *parse_arg) {
+  assert(ext_type == TLSEXT_TYPE_signed_certificate_timestamp);
+  // client SHOULD send 0 length extension_data, but it is still
+  // SHOULD, and not MUST.
+
+  // For TLSv1.3 Certificate message, sct_add_cb is called even if
+  // client has not sent signed_certificate_timestamp extension in its
+  // ClientHello.  Explicitly remember that client has included it
+  // here.
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  conn->tls.sct_requested = true;
+
+  return 1;
+}
+} // namespace
+
+#  if !OPENSSL_1_1_1_API
+
+namespace {
+int legacy_sct_add_cb(SSL *ssl, unsigned int ext_type,
+                      const unsigned char **out, size_t *outlen, int *al,
+                      void *add_arg) {
+  return sct_add_cb(ssl, ext_type, 0, out, outlen, nullptr, 0, al, add_arg);
+}
+} // namespace
+
+namespace {
+void legacy_sct_free_cb(SSL *ssl, unsigned int ext_type,
+                        const unsigned char *out, void *add_arg) {
+  sct_free_cb(ssl, ext_type, 0, out, add_arg);
+}
+} // namespace
+
+namespace {
+int legacy_sct_parse_cb(SSL *ssl, unsigned int ext_type,
+                        const unsigned char *in, size_t inlen, int *al,
+                        void *parse_arg) {
+  return sct_parse_cb(ssl, ext_type, 0, in, inlen, nullptr, 0, al, parse_arg);
+}
+} // namespace
+
+#  endif // !OPENSSL_1_1_1_API
+#endif   // !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L &&
+         // !defined(OPENSSL_IS_BORINGSSL)
+
+#ifndef OPENSSL_NO_PSK
+namespace {
+unsigned int psk_server_cb(SSL *ssl, const char *identity, unsigned char *psk,
+                           unsigned int max_psk_len) {
+  auto config = get_config();
+  auto &tlsconf = config->tls;
+
+  auto it = tlsconf.psk_secrets.find(StringRef{identity});
+  if (it == std::end(tlsconf.psk_secrets)) {
+    return 0;
+  }
+
+  auto &secret = (*it).second;
+  if (secret.size() > max_psk_len) {
+    LOG(ERROR) << "The size of PSK secret is " << secret.size()
+               << ", but the acceptable maximum size is" << max_psk_len;
+    return 0;
+  }
+
+  std::copy(std::begin(secret), std::end(secret), psk);
+
+  return static_cast<unsigned int>(secret.size());
+}
+} // namespace
+#endif // !OPENSSL_NO_PSK
+
+#ifndef OPENSSL_NO_PSK
+namespace {
+unsigned int psk_client_cb(SSL *ssl, const char *hint, char *identity_out,
+                           unsigned int max_identity_len, unsigned char *psk,
+                           unsigned int max_psk_len) {
+  auto config = get_config();
+  auto &tlsconf = config->tls;
+
+  auto &identity = tlsconf.client.psk.identity;
+  auto &secret = tlsconf.client.psk.secret;
+
+  if (identity.empty()) {
+    return 0;
+  }
+
+  if (identity.size() + 1 > max_identity_len) {
+    LOG(ERROR) << "The size of PSK identity is " << identity.size()
+               << ", but the acceptable maximum size is " << max_identity_len;
+    return 0;
+  }
+
+  if (secret.size() > max_psk_len) {
+    LOG(ERROR) << "The size of PSK secret is " << secret.size()
+               << ", but the acceptable maximum size is " << max_psk_len;
+    return 0;
+  }
+
+  *std::copy(std::begin(identity), std::end(identity), identity_out) = '\0';
+  std::copy(std::begin(secret), std::end(secret), psk);
+
+  return static_cast<unsigned int>(secret.size());
+}
+} // namespace
+#endif // !OPENSSL_NO_PSK
+
+struct TLSProtocol {
+  StringRef name;
+  long int mask;
+};
+
+constexpr TLSProtocol TLS_PROTOS[] = {
+    TLSProtocol{StringRef::from_lit("TLSv1.2"), SSL_OP_NO_TLSv1_2},
+    TLSProtocol{StringRef::from_lit("TLSv1.1"), SSL_OP_NO_TLSv1_1},
+    TLSProtocol{StringRef::from_lit("TLSv1.0"), SSL_OP_NO_TLSv1}};
+
+long int create_tls_proto_mask(const std::vector<StringRef> &tls_proto_list) {
+  long int res = 0;
+
+  for (auto &supported : TLS_PROTOS) {
+    auto ok = false;
+    for (auto &name : tls_proto_list) {
+      if (util::strieq(supported.name, name)) {
+        ok = true;
+        break;
+      }
+    }
+    if (!ok) {
+      res |= supported.mask;
+    }
+  }
+  return res;
+}
+
+SSL_CTX *create_ssl_context(const char *private_key_file, const char *cert_file,
+                            const std::vector<uint8_t> &sct_data
+#ifdef HAVE_NEVERBLEED
+                            ,
+                            neverbleed_t *nb
+#endif // HAVE_NEVERBLEED
+) {
+  auto ssl_ctx = SSL_CTX_new(TLS_server_method());
+  if (!ssl_ctx) {
+    LOG(FATAL) << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+
+  auto ssl_opts = (SSL_OP_ALL & ~SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS) |
+                  SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | SSL_OP_NO_COMPRESSION |
+                  SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION |
+                  SSL_OP_SINGLE_ECDH_USE | SSL_OP_SINGLE_DH_USE |
+                  SSL_OP_CIPHER_SERVER_PREFERENCE
+#if OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+                  // The reason for disabling built-in anti-replay in
+                  // OpenSSL is that it only works if client gets back
+                  // to the same server.  The freshness check
+                  // described in
+                  // https://tools.ietf.org/html/rfc8446#section-8.3
+                  // is still performed.
+                  | SSL_OP_NO_ANTI_REPLAY
+#endif // OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+      ;
+
+  auto config = mod_config();
+  auto &tlsconf = config->tls;
+
+#ifdef SSL_OP_ENABLE_KTLS
+  if (tlsconf.ktls) {
+    ssl_opts |= SSL_OP_ENABLE_KTLS;
+  }
+#endif // SSL_OP_ENABLE_KTLS
+
+  SSL_CTX_set_options(ssl_ctx, ssl_opts | tlsconf.tls_proto_mask);
+
+  if (nghttp2::tls::ssl_ctx_set_proto_versions(
+          ssl_ctx, tlsconf.min_proto_version, tlsconf.max_proto_version) != 0) {
+    LOG(FATAL) << "Could not set TLS protocol version";
+    DIE();
+  }
+
+  const unsigned char sid_ctx[] = "shrpx";
+  SSL_CTX_set_session_id_context(ssl_ctx, sid_ctx, sizeof(sid_ctx) - 1);
+  SSL_CTX_set_session_cache_mode(ssl_ctx, SSL_SESS_CACHE_SERVER);
+
+  if (!tlsconf.session_cache.memcached.host.empty()) {
+    SSL_CTX_sess_set_new_cb(ssl_ctx, tls_session_new_cb);
+    SSL_CTX_sess_set_get_cb(ssl_ctx, tls_session_get_cb);
+  }
+
+  SSL_CTX_set_timeout(ssl_ctx, tlsconf.session_timeout.count());
+
+  if (SSL_CTX_set_cipher_list(ssl_ctx, tlsconf.ciphers.c_str()) == 0) {
+    LOG(FATAL) << "SSL_CTX_set_cipher_list " << tlsconf.ciphers
+               << " failed: " << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+
+#if OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+  if (SSL_CTX_set_ciphersuites(ssl_ctx, tlsconf.tls13_ciphers.c_str()) == 0) {
+    LOG(FATAL) << "SSL_CTX_set_ciphersuites " << tlsconf.tls13_ciphers
+               << " failed: " << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#endif // OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+
+#ifndef OPENSSL_NO_EC
+#  if !LIBRESSL_LEGACY_API && OPENSSL_VERSION_NUMBER >= 0x10002000L
+  if (SSL_CTX_set1_curves_list(ssl_ctx, tlsconf.ecdh_curves.c_str()) != 1) {
+    LOG(FATAL) << "SSL_CTX_set1_curves_list " << tlsconf.ecdh_curves
+               << " failed";
+    DIE();
+  }
+#    if !defined(OPENSSL_IS_BORINGSSL) && !OPENSSL_1_1_API
+  // It looks like we need this function call for OpenSSL 1.0.2.  This
+  // function was deprecated in OpenSSL 1.1.0 and BoringSSL.
+  SSL_CTX_set_ecdh_auto(ssl_ctx, 1);
+#    endif // !defined(OPENSSL_IS_BORINGSSL) && !OPENSSL_1_1_API
+#  else    // LIBRESSL_LEGACY_API || OPENSSL_VERSION_NUBMER < 0x10002000L
+  // Use P-256, which is sufficiently secure at the time of this
+  // writing.
+  auto ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
+  if (ecdh == nullptr) {
+    LOG(FATAL) << "EC_KEY_new_by_curv_name failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+  SSL_CTX_set_tmp_ecdh(ssl_ctx, ecdh);
+  EC_KEY_free(ecdh);
+#  endif   // LIBRESSL_LEGACY_API || OPENSSL_VERSION_NUBMER < 0x10002000L
+#endif     // OPENSSL_NO_EC
+
+  if (!tlsconf.dh_param_file.empty()) {
+    // Read DH parameters from file
+    auto bio = BIO_new_file(tlsconf.dh_param_file.c_str(), "rb");
+    if (bio == nullptr) {
+      LOG(FATAL) << "BIO_new_file() failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#if OPENSSL_3_0_0_API
+    EVP_PKEY *dh = nullptr;
+    auto dctx = OSSL_DECODER_CTX_new_for_pkey(
+        &dh, "PEM", nullptr, "DH", OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS,
+        nullptr, nullptr);
+
+    if (!OSSL_DECODER_from_bio(dctx, bio)) {
+      LOG(FATAL) << "OSSL_DECODER_from_bio() failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+
+    if (SSL_CTX_set0_tmp_dh_pkey(ssl_ctx, dh) != 1) {
+      LOG(FATAL) << "SSL_CTX_set0_tmp_dh_pkey failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#else  // !OPENSSL_3_0_0_API
+    auto dh = PEM_read_bio_DHparams(bio, nullptr, nullptr, nullptr);
+    if (dh == nullptr) {
+      LOG(FATAL) << "PEM_read_bio_DHparams() failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+    SSL_CTX_set_tmp_dh(ssl_ctx, dh);
+    DH_free(dh);
+#endif // !OPENSSL_3_0_0_API
+    BIO_free(bio);
+  }
+
+  SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
+
+  if (SSL_CTX_set_default_verify_paths(ssl_ctx) != 1) {
+    LOG(WARN) << "Could not load system trusted ca certificates: "
+              << ERR_error_string(ERR_get_error(), nullptr);
+  }
+
+  if (!tlsconf.cacert.empty()) {
+    if (SSL_CTX_load_verify_locations(ssl_ctx, tlsconf.cacert.c_str(),
+                                      nullptr) != 1) {
+      LOG(FATAL) << "Could not load trusted ca certificates from "
+                 << tlsconf.cacert << ": "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+  }
+
+  if (!tlsconf.private_key_passwd.empty()) {
+    SSL_CTX_set_default_passwd_cb(ssl_ctx, ssl_pem_passwd_cb);
+    SSL_CTX_set_default_passwd_cb_userdata(ssl_ctx, config);
+  }
+
+#ifndef HAVE_NEVERBLEED
+  if (SSL_CTX_use_PrivateKey_file(ssl_ctx, private_key_file,
+                                  SSL_FILETYPE_PEM) != 1) {
+    LOG(FATAL) << "SSL_CTX_use_PrivateKey_file failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#else  // HAVE_NEVERBLEED
+  std::array<char, NEVERBLEED_ERRBUF_SIZE> errbuf;
+  if (neverbleed_load_private_key_file(nb, ssl_ctx, private_key_file,
+                                       errbuf.data()) != 1) {
+    LOG(FATAL) << "neverbleed_load_private_key_file failed: " << errbuf.data();
+    DIE();
+  }
+#endif // HAVE_NEVERBLEED
+
+  if (SSL_CTX_use_certificate_chain_file(ssl_ctx, cert_file) != 1) {
+    LOG(FATAL) << "SSL_CTX_use_certificate_file failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+  if (SSL_CTX_check_private_key(ssl_ctx) != 1) {
+    LOG(FATAL) << "SSL_CTX_check_private_key failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+  if (tlsconf.client_verify.enabled) {
+    if (!tlsconf.client_verify.cacert.empty()) {
+      if (SSL_CTX_load_verify_locations(
+              ssl_ctx, tlsconf.client_verify.cacert.c_str(), nullptr) != 1) {
+
+        LOG(FATAL) << "Could not load trusted ca certificates from "
+                   << tlsconf.client_verify.cacert << ": "
+                   << ERR_error_string(ERR_get_error(), nullptr);
+        DIE();
+      }
+      // It is heard that SSL_CTX_load_verify_locations() may leave
+      // error even though it returns success. See
+      // http://forum.nginx.org/read.php?29,242540
+      ERR_clear_error();
+      auto list = SSL_load_client_CA_file(tlsconf.client_verify.cacert.c_str());
+      if (!list) {
+        LOG(FATAL) << "Could not load ca certificates from "
+                   << tlsconf.client_verify.cacert << ": "
+                   << ERR_error_string(ERR_get_error(), nullptr);
+        DIE();
+      }
+      SSL_CTX_set_client_CA_list(ssl_ctx, list);
+    }
+    SSL_CTX_set_verify(ssl_ctx,
+                       SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE |
+                           SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
+                       verify_callback);
+  }
+  SSL_CTX_set_tlsext_servername_callback(ssl_ctx, servername_callback);
+#if OPENSSL_3_0_0_API
+  SSL_CTX_set_tlsext_ticket_key_evp_cb(ssl_ctx, ticket_key_cb);
+#else  // !OPENSSL_3_0_0_API
+  SSL_CTX_set_tlsext_ticket_key_cb(ssl_ctx, ticket_key_cb);
+#endif // !OPENSSL_3_0_0_API
+#ifndef OPENSSL_IS_BORINGSSL
+  SSL_CTX_set_tlsext_status_cb(ssl_ctx, ocsp_resp_cb);
+#endif // OPENSSL_IS_BORINGSSL
+  SSL_CTX_set_info_callback(ssl_ctx, info_callback);
+
+#ifdef OPENSSL_IS_BORINGSSL
+  SSL_CTX_set_early_data_enabled(ssl_ctx, 1);
+#endif // OPENSSL_IS_BORINGSSL
+
+  // NPN advertisement
+#ifndef OPENSSL_NO_NEXTPROTONEG
+  SSL_CTX_set_next_protos_advertised_cb(ssl_ctx, next_proto_cb, nullptr);
+#endif // !OPENSSL_NO_NEXTPROTONEG
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+  // ALPN selection callback
+  SSL_CTX_set_alpn_select_cb(ssl_ctx, alpn_select_proto_cb, nullptr);
+#endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+
+  auto tls_ctx_data = new TLSContextData();
+  tls_ctx_data->cert_file = cert_file;
+  tls_ctx_data->sct_data = sct_data;
+
+  SSL_CTX_set_app_data(ssl_ctx, tls_ctx_data);
+
+#if !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L &&               \
+    !defined(OPENSSL_IS_BORINGSSL)
+  // SSL_extension_supported(TLSEXT_TYPE_signed_certificate_timestamp)
+  // returns 1, which means OpenSSL internally handles it.  But
+  // OpenSSL handles signed_certificate_timestamp extension specially,
+  // and it lets custom handler to process the extension.
+  if (!sct_data.empty()) {
+#  if OPENSSL_1_1_1_API
+    // It is not entirely clear to me that SSL_EXT_CLIENT_HELLO is
+    // required here.  sct_parse_cb is called without
+    // SSL_EXT_CLIENT_HELLO being set.  But the passed context value
+    // is SSL_EXT_CLIENT_HELLO.
+    if (SSL_CTX_add_custom_ext(
+            ssl_ctx, TLSEXT_TYPE_signed_certificate_timestamp,
+            SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO |
+                SSL_EXT_TLS1_3_CERTIFICATE | SSL_EXT_IGNORE_ON_RESUMPTION,
+            sct_add_cb, sct_free_cb, nullptr, sct_parse_cb, nullptr) != 1) {
+      LOG(FATAL) << "SSL_CTX_add_custom_ext failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#  else  // !OPENSSL_1_1_1_API
+    if (SSL_CTX_add_server_custom_ext(
+            ssl_ctx, TLSEXT_TYPE_signed_certificate_timestamp,
+            legacy_sct_add_cb, legacy_sct_free_cb, nullptr, legacy_sct_parse_cb,
+            nullptr) != 1) {
+      LOG(FATAL) << "SSL_CTX_add_server_custom_ext failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#  endif // !OPENSSL_1_1_1_API
+  }
+#elif defined(OPENSSL_IS_BORINGSSL)
+  if (!tls_ctx_data->sct_data.empty() &&
+      SSL_CTX_set_signed_cert_timestamp_list(
+          ssl_ctx, tls_ctx_data->sct_data.data(),
+          tls_ctx_data->sct_data.size()) != 1) {
+    LOG(FATAL) << "SSL_CTX_set_signed_cert_timestamp_list failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#endif // defined(OPENSSL_IS_BORINGSSL)
+
+#if OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+  if (SSL_CTX_set_max_early_data(ssl_ctx, tlsconf.max_early_data) != 1) {
+    LOG(FATAL) << "SSL_CTX_set_max_early_data failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#endif // OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+
+#ifndef OPENSSL_NO_PSK
+  SSL_CTX_set_psk_server_callback(ssl_ctx, psk_server_cb);
+#endif // !LIBRESSL_NO_PSK
+
+  return ssl_ctx;
+}
+
+#ifdef ENABLE_HTTP3
+SSL_CTX *create_quic_ssl_context(const char *private_key_file,
+                                 const char *cert_file,
+                                 const std::vector<uint8_t> &sct_data
+#  ifdef HAVE_NEVERBLEED
+                                 ,
+                                 neverbleed_t *nb
+#  endif // HAVE_NEVERBLEED
+) {
+  auto ssl_ctx = SSL_CTX_new(TLS_server_method());
+  if (!ssl_ctx) {
+    LOG(FATAL) << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+
+  constexpr auto ssl_opts =
+      (SSL_OP_ALL & ~SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS) |
+      SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION | SSL_OP_SINGLE_ECDH_USE |
+      SSL_OP_SINGLE_DH_USE |
+      SSL_OP_CIPHER_SERVER_PREFERENCE
+#  if OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+      // The reason for disabling built-in anti-replay in OpenSSL is
+      // that it only works if client gets back to the same server.
+      // The freshness check described in
+      // https://tools.ietf.org/html/rfc8446#section-8.3 is still
+      // performed.
+      | SSL_OP_NO_ANTI_REPLAY
+#  endif // OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+      ;
+
+  auto config = mod_config();
+  auto &tlsconf = config->tls;
+
+  SSL_CTX_set_options(ssl_ctx, ssl_opts);
+
+#  ifdef HAVE_LIBNGTCP2_CRYPTO_OPENSSL
+  if (ngtcp2_crypto_openssl_configure_server_context(ssl_ctx) != 0) {
+    LOG(FATAL) << "ngtcp2_crypto_openssl_configure_server_context failed";
+    DIE();
+  }
+#  endif // HAVE_LIBNGTCP2_CRYPTO_OPENSSL
+#  ifdef HAVE_LIBNGTCP2_CRYPTO_BORINGSSL
+  if (ngtcp2_crypto_boringssl_configure_server_context(ssl_ctx) != 0) {
+    LOG(FATAL) << "ngtcp2_crypto_boringssl_configure_server_context failed";
+    DIE();
+  }
+#  endif // HAVE_LIBNGTCP2_CRYPTO_BORINGSSL
+
+  const unsigned char sid_ctx[] = "shrpx";
+  SSL_CTX_set_session_id_context(ssl_ctx, sid_ctx, sizeof(sid_ctx) - 1);
+  SSL_CTX_set_session_cache_mode(ssl_ctx, SSL_SESS_CACHE_OFF);
+
+  SSL_CTX_set_timeout(ssl_ctx, tlsconf.session_timeout.count());
+
+  if (SSL_CTX_set_cipher_list(ssl_ctx, tlsconf.ciphers.c_str()) == 0) {
+    LOG(FATAL) << "SSL_CTX_set_cipher_list " << tlsconf.ciphers
+               << " failed: " << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+
+#  if OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+  if (SSL_CTX_set_ciphersuites(ssl_ctx, tlsconf.tls13_ciphers.c_str()) == 0) {
+    LOG(FATAL) << "SSL_CTX_set_ciphersuites " << tlsconf.tls13_ciphers
+               << " failed: " << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#  endif // OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+
+#  ifndef OPENSSL_NO_EC
+#    if !LIBRESSL_LEGACY_API && OPENSSL_VERSION_NUMBER >= 0x10002000L
+  if (SSL_CTX_set1_curves_list(ssl_ctx, tlsconf.ecdh_curves.c_str()) != 1) {
+    LOG(FATAL) << "SSL_CTX_set1_curves_list " << tlsconf.ecdh_curves
+               << " failed";
+    DIE();
+  }
+#      if !defined(OPENSSL_IS_BORINGSSL) && !OPENSSL_1_1_API
+  // It looks like we need this function call for OpenSSL 1.0.2.  This
+  // function was deprecated in OpenSSL 1.1.0 and BoringSSL.
+  SSL_CTX_set_ecdh_auto(ssl_ctx, 1);
+#      endif // !defined(OPENSSL_IS_BORINGSSL) && !OPENSSL_1_1_API
+#    else    // LIBRESSL_LEGACY_API || OPENSSL_VERSION_NUBMER < 0x10002000L
+  // Use P-256, which is sufficiently secure at the time of this
+  // writing.
+  auto ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
+  if (ecdh == nullptr) {
+    LOG(FATAL) << "EC_KEY_new_by_curv_name failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+  SSL_CTX_set_tmp_ecdh(ssl_ctx, ecdh);
+  EC_KEY_free(ecdh);
+#    endif   // LIBRESSL_LEGACY_API || OPENSSL_VERSION_NUBMER < 0x10002000L
+#  endif     // OPENSSL_NO_EC
+
+  if (!tlsconf.dh_param_file.empty()) {
+    // Read DH parameters from file
+    auto bio = BIO_new_file(tlsconf.dh_param_file.c_str(), "rb");
+    if (bio == nullptr) {
+      LOG(FATAL) << "BIO_new_file() failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#  if OPENSSL_3_0_0_API
+    EVP_PKEY *dh = nullptr;
+    auto dctx = OSSL_DECODER_CTX_new_for_pkey(
+        &dh, "PEM", nullptr, "DH", OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS,
+        nullptr, nullptr);
+
+    if (!OSSL_DECODER_from_bio(dctx, bio)) {
+      LOG(FATAL) << "OSSL_DECODER_from_bio() failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+
+    if (SSL_CTX_set0_tmp_dh_pkey(ssl_ctx, dh) != 1) {
+      LOG(FATAL) << "SSL_CTX_set0_tmp_dh_pkey failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#  else  // !OPENSSL_3_0_0_API
+    auto dh = PEM_read_bio_DHparams(bio, nullptr, nullptr, nullptr);
+    if (dh == nullptr) {
+      LOG(FATAL) << "PEM_read_bio_DHparams() failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+    SSL_CTX_set_tmp_dh(ssl_ctx, dh);
+    DH_free(dh);
+#  endif // !OPENSSL_3_0_0_API
+    BIO_free(bio);
+  }
+
+  SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
+
+  if (SSL_CTX_set_default_verify_paths(ssl_ctx) != 1) {
+    LOG(WARN) << "Could not load system trusted ca certificates: "
+              << ERR_error_string(ERR_get_error(), nullptr);
+  }
+
+  if (!tlsconf.cacert.empty()) {
+    if (SSL_CTX_load_verify_locations(ssl_ctx, tlsconf.cacert.c_str(),
+                                      nullptr) != 1) {
+      LOG(FATAL) << "Could not load trusted ca certificates from "
+                 << tlsconf.cacert << ": "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+  }
+
+  if (!tlsconf.private_key_passwd.empty()) {
+    SSL_CTX_set_default_passwd_cb(ssl_ctx, ssl_pem_passwd_cb);
+    SSL_CTX_set_default_passwd_cb_userdata(ssl_ctx, config);
+  }
+
+#  ifndef HAVE_NEVERBLEED
+  if (SSL_CTX_use_PrivateKey_file(ssl_ctx, private_key_file,
+                                  SSL_FILETYPE_PEM) != 1) {
+    LOG(FATAL) << "SSL_CTX_use_PrivateKey_file failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#  else  // HAVE_NEVERBLEED
+  std::array<char, NEVERBLEED_ERRBUF_SIZE> errbuf;
+  if (neverbleed_load_private_key_file(nb, ssl_ctx, private_key_file,
+                                       errbuf.data()) != 1) {
+    LOG(FATAL) << "neverbleed_load_private_key_file failed: " << errbuf.data();
+    DIE();
+  }
+#  endif // HAVE_NEVERBLEED
+
+  if (SSL_CTX_use_certificate_chain_file(ssl_ctx, cert_file) != 1) {
+    LOG(FATAL) << "SSL_CTX_use_certificate_file failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+  if (SSL_CTX_check_private_key(ssl_ctx) != 1) {
+    LOG(FATAL) << "SSL_CTX_check_private_key failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+  if (tlsconf.client_verify.enabled) {
+    if (!tlsconf.client_verify.cacert.empty()) {
+      if (SSL_CTX_load_verify_locations(
+              ssl_ctx, tlsconf.client_verify.cacert.c_str(), nullptr) != 1) {
+
+        LOG(FATAL) << "Could not load trusted ca certificates from "
+                   << tlsconf.client_verify.cacert << ": "
+                   << ERR_error_string(ERR_get_error(), nullptr);
+        DIE();
+      }
+      // It is heard that SSL_CTX_load_verify_locations() may leave
+      // error even though it returns success. See
+      // http://forum.nginx.org/read.php?29,242540
+      ERR_clear_error();
+      auto list = SSL_load_client_CA_file(tlsconf.client_verify.cacert.c_str());
+      if (!list) {
+        LOG(FATAL) << "Could not load ca certificates from "
+                   << tlsconf.client_verify.cacert << ": "
+                   << ERR_error_string(ERR_get_error(), nullptr);
+        DIE();
+      }
+      SSL_CTX_set_client_CA_list(ssl_ctx, list);
+    }
+    SSL_CTX_set_verify(ssl_ctx,
+                       SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE |
+                           SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
+                       verify_callback);
+  }
+  SSL_CTX_set_tlsext_servername_callback(ssl_ctx, servername_callback);
+#  if OPENSSL_3_0_0_API
+  SSL_CTX_set_tlsext_ticket_key_evp_cb(ssl_ctx, ticket_key_cb);
+#  else  // !OPENSSL_3_0_0_API
+  SSL_CTX_set_tlsext_ticket_key_cb(ssl_ctx, ticket_key_cb);
+#  endif // !OPENSSL_3_0_0_API
+#  ifndef OPENSSL_IS_BORINGSSL
+  SSL_CTX_set_tlsext_status_cb(ssl_ctx, ocsp_resp_cb);
+#  endif // OPENSSL_IS_BORINGSSL
+
+#  if OPENSSL_VERSION_NUMBER >= 0x10002000L
+  // ALPN selection callback
+  SSL_CTX_set_alpn_select_cb(ssl_ctx, quic_alpn_select_proto_cb, nullptr);
+#  endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+
+  auto tls_ctx_data = new TLSContextData();
+  tls_ctx_data->cert_file = cert_file;
+  tls_ctx_data->sct_data = sct_data;
+
+  SSL_CTX_set_app_data(ssl_ctx, tls_ctx_data);
+
+#  if !LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L &&             \
+      !defined(OPENSSL_IS_BORINGSSL)
+  // SSL_extension_supported(TLSEXT_TYPE_signed_certificate_timestamp)
+  // returns 1, which means OpenSSL internally handles it.  But
+  // OpenSSL handles signed_certificate_timestamp extension specially,
+  // and it lets custom handler to process the extension.
+  if (!sct_data.empty()) {
+#    if OPENSSL_1_1_1_API
+    // It is not entirely clear to me that SSL_EXT_CLIENT_HELLO is
+    // required here.  sct_parse_cb is called without
+    // SSL_EXT_CLIENT_HELLO being set.  But the passed context value
+    // is SSL_EXT_CLIENT_HELLO.
+    if (SSL_CTX_add_custom_ext(
+            ssl_ctx, TLSEXT_TYPE_signed_certificate_timestamp,
+            SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO |
+                SSL_EXT_TLS1_3_CERTIFICATE | SSL_EXT_IGNORE_ON_RESUMPTION,
+            sct_add_cb, sct_free_cb, nullptr, sct_parse_cb, nullptr) != 1) {
+      LOG(FATAL) << "SSL_CTX_add_custom_ext failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#    else  // !OPENSSL_1_1_1_API
+    if (SSL_CTX_add_server_custom_ext(
+            ssl_ctx, TLSEXT_TYPE_signed_certificate_timestamp,
+            legacy_sct_add_cb, legacy_sct_free_cb, nullptr, legacy_sct_parse_cb,
+            nullptr) != 1) {
+      LOG(FATAL) << "SSL_CTX_add_server_custom_ext failed: "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#    endif // !OPENSSL_1_1_1_API
+  }
+#  elif defined(OPENSSL_IS_BORINGSSL)
+  if (!tls_ctx_data->sct_data.empty() &&
+      SSL_CTX_set_signed_cert_timestamp_list(
+          ssl_ctx, tls_ctx_data->sct_data.data(),
+          tls_ctx_data->sct_data.size()) != 1) {
+    LOG(FATAL) << "SSL_CTX_set_signed_cert_timestamp_list failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#  endif // defined(OPENSSL_IS_BORINGSSL)
+
+#  if OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+  auto &quicconf = config->quic;
+
+  if (quicconf.upstream.early_data &&
+      SSL_CTX_set_max_early_data(ssl_ctx,
+                                 std::numeric_limits<uint32_t>::max()) != 1) {
+    LOG(FATAL) << "SSL_CTX_set_max_early_data failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#  endif // OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+
+#  ifndef OPENSSL_NO_PSK
+  SSL_CTX_set_psk_server_callback(ssl_ctx, psk_server_cb);
+#  endif // !LIBRESSL_NO_PSK
+
+  return ssl_ctx;
+}
+#endif // ENABLE_HTTP3
+
+namespace {
+int select_h2_next_proto_cb(SSL *ssl, unsigned char **out,
+                            unsigned char *outlen, const unsigned char *in,
+                            unsigned int inlen, void *arg) {
+  if (!util::select_h2(const_cast<const unsigned char **>(out), outlen, in,
+                       inlen)) {
+    return SSL_TLSEXT_ERR_NOACK;
+  }
+
+  return SSL_TLSEXT_ERR_OK;
+}
+} // namespace
+
+namespace {
+int select_h1_next_proto_cb(SSL *ssl, unsigned char **out,
+                            unsigned char *outlen, const unsigned char *in,
+                            unsigned int inlen, void *arg) {
+  auto end = in + inlen;
+  for (; in < end;) {
+    if (util::streq(NGHTTP2_H1_1_ALPN, StringRef{in, in + (in[0] + 1)})) {
+      *out = const_cast<unsigned char *>(in) + 1;
+      *outlen = in[0];
+      return SSL_TLSEXT_ERR_OK;
+    }
+    in += in[0] + 1;
+  }
+
+  return SSL_TLSEXT_ERR_NOACK;
+}
+} // namespace
+
+namespace {
+int select_next_proto_cb(SSL *ssl, unsigned char **out, unsigned char *outlen,
+                         const unsigned char *in, unsigned int inlen,
+                         void *arg) {
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  switch (conn->proto) {
+  case Proto::HTTP1:
+    return select_h1_next_proto_cb(ssl, out, outlen, in, inlen, arg);
+  case Proto::HTTP2:
+    return select_h2_next_proto_cb(ssl, out, outlen, in, inlen, arg);
+  default:
+    return SSL_TLSEXT_ERR_NOACK;
+  }
+}
+} // namespace
+
+SSL_CTX *create_ssl_client_context(
+#ifdef HAVE_NEVERBLEED
+    neverbleed_t *nb,
+#endif // HAVE_NEVERBLEED
+    const StringRef &cacert, const StringRef &cert_file,
+    const StringRef &private_key_file,
+    int (*next_proto_select_cb)(SSL *s, unsigned char **out,
+                                unsigned char *outlen, const unsigned char *in,
+                                unsigned int inlen, void *arg)) {
+  auto ssl_ctx = SSL_CTX_new(TLS_client_method());
+  if (!ssl_ctx) {
+    LOG(FATAL) << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+
+  auto ssl_opts = (SSL_OP_ALL & ~SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS) |
+                  SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | SSL_OP_NO_COMPRESSION |
+                  SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION;
+
+  auto &tlsconf = get_config()->tls;
+
+#ifdef SSL_OP_ENABLE_KTLS
+  if (tlsconf.ktls) {
+    ssl_opts |= SSL_OP_ENABLE_KTLS;
+  }
+#endif // SSL_OP_ENABLE_KTLS
+
+  SSL_CTX_set_options(ssl_ctx, ssl_opts | tlsconf.tls_proto_mask);
+
+  SSL_CTX_set_session_cache_mode(ssl_ctx, SSL_SESS_CACHE_CLIENT |
+                                              SSL_SESS_CACHE_NO_INTERNAL_STORE);
+  SSL_CTX_sess_set_new_cb(ssl_ctx, tls_session_client_new_cb);
+
+  if (nghttp2::tls::ssl_ctx_set_proto_versions(
+          ssl_ctx, tlsconf.min_proto_version, tlsconf.max_proto_version) != 0) {
+    LOG(FATAL) << "Could not set TLS protocol version";
+    DIE();
+  }
+
+  if (SSL_CTX_set_cipher_list(ssl_ctx, tlsconf.client.ciphers.c_str()) == 0) {
+    LOG(FATAL) << "SSL_CTX_set_cipher_list " << tlsconf.client.ciphers
+               << " failed: " << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+
+#if OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+  if (SSL_CTX_set_ciphersuites(ssl_ctx, tlsconf.client.tls13_ciphers.c_str()) ==
+      0) {
+    LOG(FATAL) << "SSL_CTX_set_ciphersuites " << tlsconf.client.tls13_ciphers
+               << " failed: " << ERR_error_string(ERR_get_error(), nullptr);
+    DIE();
+  }
+#endif // OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+
+  SSL_CTX_set_mode(ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
+
+  if (SSL_CTX_set_default_verify_paths(ssl_ctx) != 1) {
+    LOG(WARN) << "Could not load system trusted ca certificates: "
+              << ERR_error_string(ERR_get_error(), nullptr);
+  }
+
+  if (!cacert.empty()) {
+    if (SSL_CTX_load_verify_locations(ssl_ctx, cacert.c_str(), nullptr) != 1) {
+
+      LOG(FATAL) << "Could not load trusted ca certificates from " << cacert
+                 << ": " << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+  }
+
+  if (!tlsconf.insecure) {
+    SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, nullptr);
+  }
+
+  if (!cert_file.empty()) {
+    if (SSL_CTX_use_certificate_chain_file(ssl_ctx, cert_file.c_str()) != 1) {
+
+      LOG(FATAL) << "Could not load client certificate from " << cert_file
+                 << ": " << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+  }
+
+  if (!private_key_file.empty()) {
+#ifndef HAVE_NEVERBLEED
+    if (SSL_CTX_use_PrivateKey_file(ssl_ctx, private_key_file.c_str(),
+                                    SSL_FILETYPE_PEM) != 1) {
+      LOG(FATAL) << "Could not load client private key from "
+                 << private_key_file << ": "
+                 << ERR_error_string(ERR_get_error(), nullptr);
+      DIE();
+    }
+#else  // HAVE_NEVERBLEED
+    std::array<char, NEVERBLEED_ERRBUF_SIZE> errbuf;
+    if (neverbleed_load_private_key_file(nb, ssl_ctx, private_key_file.c_str(),
+                                         errbuf.data()) != 1) {
+      LOG(FATAL) << "neverbleed_load_private_key_file: could not load client "
+                    "private key from "
+                 << private_key_file << ": " << errbuf.data();
+      DIE();
+    }
+#endif // HAVE_NEVERBLEED
+  }
+
+#ifndef OPENSSL_NO_PSK
+  SSL_CTX_set_psk_client_callback(ssl_ctx, psk_client_cb);
+#endif // !OPENSSL_NO_PSK
+
+  // NPN selection callback.  This is required to set SSL_CTX because
+  // OpenSSL does not offer SSL_set_next_proto_select_cb.
+#ifndef OPENSSL_NO_NEXTPROTONEG
+  SSL_CTX_set_next_proto_select_cb(ssl_ctx, next_proto_select_cb, nullptr);
+#endif // !OPENSSL_NO_NEXTPROTONEG
+
+  return ssl_ctx;
+}
+
+SSL *create_ssl(SSL_CTX *ssl_ctx) {
+  auto ssl = SSL_new(ssl_ctx);
+  if (!ssl) {
+    LOG(ERROR) << "SSL_new() failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    return nullptr;
+  }
+
+  return ssl;
+}
+
+ClientHandler *accept_connection(Worker *worker, int fd, sockaddr *addr,
+                                 int addrlen, const UpstreamAddr *faddr) {
+  std::array<char, NI_MAXHOST> host;
+  std::array<char, NI_MAXSERV> service;
+  int rv;
+
+  if (addr->sa_family == AF_UNIX) {
+    std::copy_n("localhost", sizeof("localhost"), std::begin(host));
+    service[0] = '\0';
+  } else {
+    rv = getnameinfo(addr, addrlen, host.data(), host.size(), service.data(),
+                     service.size(), NI_NUMERICHOST | NI_NUMERICSERV);
+    if (rv != 0) {
+      LOG(ERROR) << "getnameinfo() failed: " << gai_strerror(rv);
+
+      return nullptr;
+    }
+
+    rv = util::make_socket_nodelay(fd);
+    if (rv == -1) {
+      LOG(WARN) << "Setting option TCP_NODELAY failed: errno=" << errno;
+    }
+  }
+  SSL *ssl = nullptr;
+  if (faddr->tls) {
+    auto ssl_ctx = worker->get_sv_ssl_ctx();
+
+    assert(ssl_ctx);
+
+    ssl = create_ssl(ssl_ctx);
+    if (!ssl) {
+      return nullptr;
+    }
+    // Disable TLS session ticket if we don't have working ticket
+    // keys.
+    if (!worker->get_ticket_keys()) {
+      SSL_set_options(ssl, SSL_OP_NO_TICKET);
+    }
+  }
+
+  return new ClientHandler(worker, fd, ssl, StringRef{host.data()},
+                           StringRef{service.data()}, addr->sa_family, faddr);
+}
+
+bool tls_hostname_match(const StringRef &pattern, const StringRef &hostname) {
+  auto ptWildcard = std::find(std::begin(pattern), std::end(pattern), '*');
+  if (ptWildcard == std::end(pattern)) {
+    return util::strieq(pattern, hostname);
+  }
+
+  auto ptLeftLabelEnd = std::find(std::begin(pattern), std::end(pattern), '.');
+  auto wildcardEnabled = true;
+  // Do case-insensitive match. At least 2 dots are required to enable
+  // wildcard match. Also wildcard must be in the left-most label.
+  // Don't attempt to match a presented identifier where the wildcard
+  // character is embedded within an A-label.
+  if (ptLeftLabelEnd == std::end(pattern) ||
+      std::find(ptLeftLabelEnd + 1, std::end(pattern), '.') ==
+          std::end(pattern) ||
+      ptLeftLabelEnd < ptWildcard || util::istarts_with_l(pattern, "xn--")) {
+    wildcardEnabled = false;
+  }
+
+  if (!wildcardEnabled) {
+    return util::strieq(pattern, hostname);
+  }
+
+  auto hnLeftLabelEnd =
+      std::find(std::begin(hostname), std::end(hostname), '.');
+  if (hnLeftLabelEnd == std::end(hostname) ||
+      !util::strieq(StringRef{ptLeftLabelEnd, std::end(pattern)},
+                    StringRef{hnLeftLabelEnd, std::end(hostname)})) {
+    return false;
+  }
+  // Perform wildcard match. Here '*' must match at least one
+  // character.
+  if (hnLeftLabelEnd - std::begin(hostname) <
+      ptLeftLabelEnd - std::begin(pattern)) {
+    return false;
+  }
+  return util::istarts_with(StringRef{std::begin(hostname), hnLeftLabelEnd},
+                            StringRef{std::begin(pattern), ptWildcard}) &&
+         util::iends_with(StringRef{std::begin(hostname), hnLeftLabelEnd},
+                          StringRef{ptWildcard + 1, ptLeftLabelEnd});
+}
+
+namespace {
+// if return value is not empty, StringRef.c_str() must be freed using
+// OPENSSL_free().
+StringRef get_common_name(X509 *cert) {
+  auto subjectname = X509_get_subject_name(cert);
+  if (!subjectname) {
+    LOG(WARN) << "Could not get X509 name object from the certificate.";
+    return StringRef{};
+  }
+  int lastpos = -1;
+  for (;;) {
+    lastpos = X509_NAME_get_index_by_NID(subjectname, NID_commonName, lastpos);
+    if (lastpos == -1) {
+      break;
+    }
+    auto entry = X509_NAME_get_entry(subjectname, lastpos);
+
+    unsigned char *p;
+    auto plen = ASN1_STRING_to_UTF8(&p, X509_NAME_ENTRY_get_data(entry));
+    if (plen < 0) {
+      continue;
+    }
+    if (std::find(p, p + plen, '\0') != p + plen) {
+      // Embedded NULL is not permitted.
+      continue;
+    }
+    if (plen == 0) {
+      LOG(WARN) << "X509 name is empty";
+      OPENSSL_free(p);
+      continue;
+    }
+
+    return StringRef{p, static_cast<size_t>(plen)};
+  }
+  return StringRef{};
+}
+} // namespace
+
+namespace {
+int verify_numeric_hostname(X509 *cert, const StringRef &hostname,
+                            const Address *addr) {
+  const void *saddr;
+  switch (addr->su.storage.ss_family) {
+  case AF_INET:
+    saddr = &addr->su.in.sin_addr;
+    break;
+  case AF_INET6:
+    saddr = &addr->su.in6.sin6_addr;
+    break;
+  default:
+    return -1;
+  }
+
+  auto altnames = static_cast<GENERAL_NAMES *>(
+      X509_get_ext_d2i(cert, NID_subject_alt_name, nullptr, nullptr));
+  if (altnames) {
+    auto altnames_deleter = defer(GENERAL_NAMES_free, altnames);
+    size_t n = sk_GENERAL_NAME_num(altnames);
+    auto ip_found = false;
+    for (size_t i = 0; i < n; ++i) {
+      auto altname = sk_GENERAL_NAME_value(altnames, i);
+      if (altname->type != GEN_IPADD) {
+        continue;
+      }
+
+      auto ip_addr = altname->d.iPAddress->data;
+      if (!ip_addr) {
+        continue;
+      }
+      size_t ip_addrlen = altname->d.iPAddress->length;
+
+      ip_found = true;
+      if (addr->len == ip_addrlen && memcmp(saddr, ip_addr, ip_addrlen) == 0) {
+        return 0;
+      }
+    }
+
+    if (ip_found) {
+      return -1;
+    }
+  }
+
+  auto cn = get_common_name(cert);
+  if (cn.empty()) {
+    return -1;
+  }
+
+  // cn is not NULL terminated
+  auto rv = util::streq(hostname, cn);
+  OPENSSL_free(const_cast<char *>(cn.c_str()));
+
+  if (rv) {
+    return 0;
+  }
+
+  return -1;
+}
+} // namespace
+
+namespace {
+int verify_hostname(X509 *cert, const StringRef &hostname,
+                    const Address *addr) {
+  if (util::numeric_host(hostname.c_str())) {
+    return verify_numeric_hostname(cert, hostname, addr);
+  }
+
+  auto altnames = static_cast<GENERAL_NAMES *>(
+      X509_get_ext_d2i(cert, NID_subject_alt_name, nullptr, nullptr));
+  if (altnames) {
+    auto dns_found = false;
+    auto altnames_deleter = defer(GENERAL_NAMES_free, altnames);
+    size_t n = sk_GENERAL_NAME_num(altnames);
+    for (size_t i = 0; i < n; ++i) {
+      auto altname = sk_GENERAL_NAME_value(altnames, i);
+      if (altname->type != GEN_DNS) {
+        continue;
+      }
+
+      auto name = ASN1_STRING_get0_data(altname->d.ia5);
+      if (!name) {
+        continue;
+      }
+
+      auto len = ASN1_STRING_length(altname->d.ia5);
+      if (len == 0) {
+        continue;
+      }
+      if (std::find(name, name + len, '\0') != name + len) {
+        // Embedded NULL is not permitted.
+        continue;
+      }
+
+      if (name[len - 1] == '.') {
+        --len;
+        if (len == 0) {
+          continue;
+        }
+      }
+
+      dns_found = true;
+
+      if (tls_hostname_match(StringRef{name, static_cast<size_t>(len)},
+                             hostname)) {
+        return 0;
+      }
+    }
+
+    // RFC 6125, section 6.4.4. says that client MUST not seek a match
+    // for CN if a dns dNSName is found.
+    if (dns_found) {
+      return -1;
+    }
+  }
+
+  auto cn = get_common_name(cert);
+  if (cn.empty()) {
+    return -1;
+  }
+
+  if (cn[cn.size() - 1] == '.') {
+    if (cn.size() == 1) {
+      OPENSSL_free(const_cast<char *>(cn.c_str()));
+
+      return -1;
+    }
+    cn = StringRef{cn.c_str(), cn.size() - 1};
+  }
+
+  auto rv = tls_hostname_match(cn, hostname);
+  OPENSSL_free(const_cast<char *>(cn.c_str()));
+
+  return rv ? 0 : -1;
+}
+} // namespace
+
+int check_cert(SSL *ssl, const Address *addr, const StringRef &host) {
+#if OPENSSL_3_0_0_API
+  auto cert = SSL_get0_peer_certificate(ssl);
+#else  // !OPENSSL_3_0_0_API
+  auto cert = SSL_get_peer_certificate(ssl);
+#endif // !OPENSSL_3_0_0_API
+  if (!cert) {
+    // By the protocol definition, TLS server always sends certificate
+    // if it has.  If certificate cannot be retrieved, authentication
+    // without certificate is used, such as PSK.
+    return 0;
+  }
+#if !OPENSSL_3_0_0_API
+  auto cert_deleter = defer(X509_free, cert);
+#endif // !OPENSSL_3_0_0_API
+
+  if (verify_hostname(cert, host, addr) != 0) {
+    LOG(ERROR) << "Certificate verification failed: hostname does not match";
+    return -1;
+  }
+  return 0;
+}
+
+int check_cert(SSL *ssl, const DownstreamAddr *addr, const Address *raddr) {
+  auto hostname =
+      addr->sni.empty() ? StringRef{addr->host} : StringRef{addr->sni};
+  return check_cert(ssl, raddr, hostname);
+}
+
+CertLookupTree::CertLookupTree() {}
+
+ssize_t CertLookupTree::add_cert(const StringRef &hostname, size_t idx) {
+  std::array<uint8_t, NI_MAXHOST> buf;
+
+  // NI_MAXHOST includes terminal NULL byte
+  if (hostname.empty() || hostname.size() + 1 > buf.size()) {
+    return -1;
+  }
+
+  auto wildcard_it = std::find(std::begin(hostname), std::end(hostname), '*');
+  if (wildcard_it != std::end(hostname) &&
+      wildcard_it + 1 != std::end(hostname)) {
+    auto wildcard_prefix = StringRef{std::begin(hostname), wildcard_it};
+    auto wildcard_suffix = StringRef{wildcard_it + 1, std::end(hostname)};
+
+    auto rev_suffix = StringRef{std::begin(buf),
+                                std::reverse_copy(std::begin(wildcard_suffix),
+                                                  std::end(wildcard_suffix),
+                                                  std::begin(buf))};
+
+    WildcardPattern *wpat;
+
+    if (wildcard_patterns_.size() !=
+        rev_wildcard_router_.add_route(rev_suffix, wildcard_patterns_.size())) {
+      auto wcidx = rev_wildcard_router_.match(rev_suffix);
+
+      assert(wcidx != -1);
+
+      wpat = &wildcard_patterns_[wcidx];
+    } else {
+      wildcard_patterns_.emplace_back();
+      wpat = &wildcard_patterns_.back();
+    }
+
+    auto rev_prefix = StringRef{std::begin(buf),
+                                std::reverse_copy(std::begin(wildcard_prefix),
+                                                  std::end(wildcard_prefix),
+                                                  std::begin(buf))};
+
+    for (auto &p : wpat->rev_prefix) {
+      if (p.prefix == rev_prefix) {
+        return p.idx;
+      }
+    }
+
+    wpat->rev_prefix.emplace_back(rev_prefix, idx);
+
+    return idx;
+  }
+
+  return router_.add_route(hostname, idx);
+}
+
+ssize_t CertLookupTree::lookup(const StringRef &hostname) {
+  std::array<uint8_t, NI_MAXHOST> buf;
+
+  // NI_MAXHOST includes terminal NULL byte
+  if (hostname.empty() || hostname.size() + 1 > buf.size()) {
+    return -1;
+  }
+
+  // Always prefer exact match
+  auto idx = router_.match(hostname);
+  if (idx != -1) {
+    return idx;
+  }
+
+  if (wildcard_patterns_.empty()) {
+    return -1;
+  }
+
+  ssize_t best_idx = -1;
+  size_t best_prefixlen = 0;
+  const RNode *last_node = nullptr;
+
+  auto rev_host = StringRef{
+      std::begin(buf), std::reverse_copy(std::begin(hostname),
+                                         std::end(hostname), std::begin(buf))};
+
+  for (;;) {
+    size_t nread = 0;
+
+    auto wcidx =
+        rev_wildcard_router_.match_prefix(&nread, &last_node, rev_host);
+    if (wcidx == -1) {
+      return best_idx;
+    }
+
+    // '*' must match at least one byte
+    if (nread == rev_host.size()) {
+      return best_idx;
+    }
+
+    rev_host = StringRef{std::begin(rev_host) + nread, std::end(rev_host)};
+
+    auto rev_prefix = StringRef{std::begin(rev_host) + 1, std::end(rev_host)};
+
+    auto &wpat = wildcard_patterns_[wcidx];
+    for (auto &wprefix : wpat.rev_prefix) {
+      if (!util::ends_with(rev_prefix, wprefix.prefix)) {
+        continue;
+      }
+
+      auto prefixlen =
+          wprefix.prefix.size() +
+          (reinterpret_cast<const uint8_t *>(&rev_host[0]) - &buf[0]);
+
+      // Breaking a tie with longer suffix
+      if (prefixlen < best_prefixlen) {
+        continue;
+      }
+
+      best_idx = wprefix.idx;
+      best_prefixlen = prefixlen;
+    }
+  }
+}
+
+void CertLookupTree::dump() const {
+  std::cerr << "exact:" << std::endl;
+  router_.dump();
+  std::cerr << "wildcard suffix (reversed):" << std::endl;
+  rev_wildcard_router_.dump();
+}
+
+int cert_lookup_tree_add_ssl_ctx(
+    CertLookupTree *lt, std::vector<std::vector<SSL_CTX *>> &indexed_ssl_ctx,
+    SSL_CTX *ssl_ctx) {
+  std::array<uint8_t, NI_MAXHOST> buf;
+
+#if LIBRESSL_2_7_API ||                                                        \
+    (!LIBRESSL_IN_USE && OPENSSL_VERSION_NUMBER >= 0x10002000L)
+  auto cert = SSL_CTX_get0_certificate(ssl_ctx);
+#else  // !LIBRESSL_2_7_API && OPENSSL_VERSION_NUMBER < 0x10002000L
+  auto tls_ctx_data =
+      static_cast<TLSContextData *>(SSL_CTX_get_app_data(ssl_ctx));
+  auto cert = load_certificate(tls_ctx_data->cert_file);
+  auto cert_deleter = defer(X509_free, cert);
+#endif // !LIBRESSL_2_7_API && OPENSSL_VERSION_NUMBER < 0x10002000L
+
+  auto altnames = static_cast<GENERAL_NAMES *>(
+      X509_get_ext_d2i(cert, NID_subject_alt_name, nullptr, nullptr));
+  if (altnames) {
+    auto altnames_deleter = defer(GENERAL_NAMES_free, altnames);
+    size_t n = sk_GENERAL_NAME_num(altnames);
+    auto dns_found = false;
+    for (size_t i = 0; i < n; ++i) {
+      auto altname = sk_GENERAL_NAME_value(altnames, i);
+      if (altname->type != GEN_DNS) {
+        continue;
+      }
+
+      auto name = ASN1_STRING_get0_data(altname->d.ia5);
+      if (!name) {
+        continue;
+      }
+
+      auto len = ASN1_STRING_length(altname->d.ia5);
+      if (len == 0) {
+        continue;
+      }
+      if (std::find(name, name + len, '\0') != name + len) {
+        // Embedded NULL is not permitted.
+        continue;
+      }
+
+      if (name[len - 1] == '.') {
+        --len;
+        if (len == 0) {
+          continue;
+        }
+      }
+
+      dns_found = true;
+
+      if (static_cast<size_t>(len) + 1 > buf.size()) {
+        continue;
+      }
+
+      auto end_buf = std::copy_n(name, len, std::begin(buf));
+      util::inp_strlower(std::begin(buf), end_buf);
+
+      auto idx = lt->add_cert(StringRef{std::begin(buf), end_buf},
+                              indexed_ssl_ctx.size());
+      if (idx == -1) {
+        continue;
+      }
+
+      if (static_cast<size_t>(idx) < indexed_ssl_ctx.size()) {
+        indexed_ssl_ctx[idx].push_back(ssl_ctx);
+      } else {
+        assert(static_cast<size_t>(idx) == indexed_ssl_ctx.size());
+        indexed_ssl_ctx.emplace_back(std::vector<SSL_CTX *>{ssl_ctx});
+      }
+    }
+
+    // Don't bother CN if we have dNSName.
+    if (dns_found) {
+      return 0;
+    }
+  }
+
+  auto cn = get_common_name(cert);
+  if (cn.empty()) {
+    return 0;
+  }
+
+  if (cn[cn.size() - 1] == '.') {
+    if (cn.size() == 1) {
+      OPENSSL_free(const_cast<char *>(cn.c_str()));
+
+      return 0;
+    }
+
+    cn = StringRef{cn.c_str(), cn.size() - 1};
+  }
+
+  auto end_buf = std::copy(std::begin(cn), std::end(cn), std::begin(buf));
+
+  OPENSSL_free(const_cast<char *>(cn.c_str()));
+
+  util::inp_strlower(std::begin(buf), end_buf);
+
+  auto idx =
+      lt->add_cert(StringRef{std::begin(buf), end_buf}, indexed_ssl_ctx.size());
+  if (idx == -1) {
+    return 0;
+  }
+
+  if (static_cast<size_t>(idx) < indexed_ssl_ctx.size()) {
+    indexed_ssl_ctx[idx].push_back(ssl_ctx);
+  } else {
+    assert(static_cast<size_t>(idx) == indexed_ssl_ctx.size());
+    indexed_ssl_ctx.emplace_back(std::vector<SSL_CTX *>{ssl_ctx});
+  }
+
+  return 0;
+}
+
+bool in_proto_list(const std::vector<StringRef> &protos,
+                   const StringRef &needle) {
+  for (auto &proto : protos) {
+    if (util::streq(proto, needle)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool upstream_tls_enabled(const ConnectionConfig &connconf) {
+#ifdef ENABLE_HTTP3
+  if (connconf.quic_listener.addrs.size()) {
+    return true;
+  }
+#endif // ENABLE_HTTP3
+
+  const auto &faddrs = connconf.listener.addrs;
+  return std::any_of(std::begin(faddrs), std::end(faddrs),
+                     [](const UpstreamAddr &faddr) { return faddr.tls; });
+}
+
+X509 *load_certificate(const char *filename) {
+  auto bio = BIO_new(BIO_s_file());
+  if (!bio) {
+    fprintf(stderr, "BIO_new() failed\n");
+    return nullptr;
+  }
+  auto bio_deleter = defer(BIO_vfree, bio);
+  if (!BIO_read_filename(bio, filename)) {
+    fprintf(stderr, "Could not read certificate file '%s'\n", filename);
+    return nullptr;
+  }
+  auto cert = PEM_read_bio_X509(bio, nullptr, nullptr, nullptr);
+  if (!cert) {
+    fprintf(stderr, "Could not read X509 structure from file '%s'\n", filename);
+    return nullptr;
+  }
+
+  return cert;
+}
+
+SSL_CTX *
+setup_server_ssl_context(std::vector<SSL_CTX *> &all_ssl_ctx,
+                         std::vector<std::vector<SSL_CTX *>> &indexed_ssl_ctx,
+                         CertLookupTree *cert_tree
+#ifdef HAVE_NEVERBLEED
+                         ,
+                         neverbleed_t *nb
+#endif // HAVE_NEVERBLEED
+) {
+  auto config = get_config();
+
+  if (!upstream_tls_enabled(config->conn)) {
+    return nullptr;
+  }
+
+  auto &tlsconf = config->tls;
+
+  auto ssl_ctx = create_ssl_context(tlsconf.private_key_file.c_str(),
+                                    tlsconf.cert_file.c_str(), tlsconf.sct_data
+#ifdef HAVE_NEVERBLEED
+                                    ,
+                                    nb
+#endif // HAVE_NEVERBLEED
+  );
+
+  all_ssl_ctx.push_back(ssl_ctx);
+
+  assert(cert_tree);
+
+  if (cert_lookup_tree_add_ssl_ctx(cert_tree, indexed_ssl_ctx, ssl_ctx) == -1) {
+    LOG(FATAL) << "Failed to add default certificate.";
+    DIE();
+  }
+
+  for (auto &c : tlsconf.subcerts) {
+    auto ssl_ctx = create_ssl_context(c.private_key_file.c_str(),
+                                      c.cert_file.c_str(), c.sct_data
+#ifdef HAVE_NEVERBLEED
+                                      ,
+                                      nb
+#endif // HAVE_NEVERBLEED
+    );
+    all_ssl_ctx.push_back(ssl_ctx);
+
+    if (cert_lookup_tree_add_ssl_ctx(cert_tree, indexed_ssl_ctx, ssl_ctx) ==
+        -1) {
+      LOG(FATAL) << "Failed to add sub certificate.";
+      DIE();
+    }
+  }
+
+  return ssl_ctx;
+}
+
+#ifdef ENABLE_HTTP3
+SSL_CTX *setup_quic_server_ssl_context(
+    std::vector<SSL_CTX *> &all_ssl_ctx,
+    std::vector<std::vector<SSL_CTX *>> &indexed_ssl_ctx,
+    CertLookupTree *cert_tree
+#  ifdef HAVE_NEVERBLEED
+    ,
+    neverbleed_t *nb
+#  endif // HAVE_NEVERBLEED
+) {
+  auto config = get_config();
+
+  if (!upstream_tls_enabled(config->conn)) {
+    return nullptr;
+  }
+
+  auto &tlsconf = config->tls;
+
+  auto ssl_ctx =
+      create_quic_ssl_context(tlsconf.private_key_file.c_str(),
+                              tlsconf.cert_file.c_str(), tlsconf.sct_data
+#  ifdef HAVE_NEVERBLEED
+                              ,
+                              nb
+#  endif // HAVE_NEVERBLEED
+      );
+
+  all_ssl_ctx.push_back(ssl_ctx);
+
+  assert(cert_tree);
+
+  if (cert_lookup_tree_add_ssl_ctx(cert_tree, indexed_ssl_ctx, ssl_ctx) == -1) {
+    LOG(FATAL) << "Failed to add default certificate.";
+    DIE();
+  }
+
+  for (auto &c : tlsconf.subcerts) {
+    auto ssl_ctx = create_quic_ssl_context(c.private_key_file.c_str(),
+                                           c.cert_file.c_str(), c.sct_data
+#  ifdef HAVE_NEVERBLEED
+                                           ,
+                                           nb
+#  endif // HAVE_NEVERBLEED
+    );
+    all_ssl_ctx.push_back(ssl_ctx);
+
+    if (cert_lookup_tree_add_ssl_ctx(cert_tree, indexed_ssl_ctx, ssl_ctx) ==
+        -1) {
+      LOG(FATAL) << "Failed to add sub certificate.";
+      DIE();
+    }
+  }
+
+  return ssl_ctx;
+}
+#endif // ENABLE_HTTP3
+
+SSL_CTX *setup_downstream_client_ssl_context(
+#ifdef HAVE_NEVERBLEED
+    neverbleed_t *nb
+#endif // HAVE_NEVERBLEED
+) {
+  auto &tlsconf = get_config()->tls;
+
+  return create_ssl_client_context(
+#ifdef HAVE_NEVERBLEED
+      nb,
+#endif // HAVE_NEVERBLEED
+      tlsconf.cacert, tlsconf.client.cert_file, tlsconf.client.private_key_file,
+      select_next_proto_cb);
+}
+
+void setup_downstream_http2_alpn(SSL *ssl) {
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+  // ALPN advertisement
+  auto alpn = util::get_default_alpn();
+  SSL_set_alpn_protos(ssl, alpn.data(), alpn.size());
+#endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+}
+
+void setup_downstream_http1_alpn(SSL *ssl) {
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+  // ALPN advertisement
+  SSL_set_alpn_protos(ssl, NGHTTP2_H1_1_ALPN.byte(), NGHTTP2_H1_1_ALPN.size());
+#endif // OPENSSL_VERSION_NUMBER >= 0x10002000L
+}
+
+std::unique_ptr<CertLookupTree> create_cert_lookup_tree() {
+  auto config = get_config();
+  if (!upstream_tls_enabled(config->conn)) {
+    return nullptr;
+  }
+  return std::make_unique<CertLookupTree>();
+}
+
+namespace {
+std::vector<uint8_t> serialize_ssl_session(SSL_SESSION *session) {
+  auto len = i2d_SSL_SESSION(session, nullptr);
+  auto buf = std::vector<uint8_t>(len);
+  auto p = buf.data();
+  i2d_SSL_SESSION(session, &p);
+
+  return buf;
+}
+} // namespace
+
+void try_cache_tls_session(TLSSessionCache *cache, SSL_SESSION *session,
+                           ev_tstamp t) {
+  if (cache->last_updated + 1_min > t) {
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "Client session cache entry is still fresh.";
+    }
+    return;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    LOG(INFO) << "Update client cache entry "
+              << "timestamp = " << t;
+  }
+
+  cache->session_data = serialize_ssl_session(session);
+  cache->last_updated = t;
+}
+
+SSL_SESSION *reuse_tls_session(const TLSSessionCache &cache) {
+  if (cache.session_data.empty()) {
+    return nullptr;
+  }
+
+  auto p = cache.session_data.data();
+  return d2i_SSL_SESSION(nullptr, &p, cache.session_data.size());
+}
+
+int proto_version_from_string(const StringRef &v) {
+#ifdef TLS1_3_VERSION
+  if (util::strieq_l("TLSv1.3", v)) {
+    return TLS1_3_VERSION;
+  }
+#endif // TLS1_3_VERSION
+  if (util::strieq_l("TLSv1.2", v)) {
+    return TLS1_2_VERSION;
+  }
+  if (util::strieq_l("TLSv1.1", v)) {
+    return TLS1_1_VERSION;
+  }
+  if (util::strieq_l("TLSv1.0", v)) {
+    return TLS1_VERSION;
+  }
+  return -1;
+}
+
+int verify_ocsp_response(SSL_CTX *ssl_ctx, const uint8_t *ocsp_resp,
+                         size_t ocsp_resplen) {
+
+#if !defined(OPENSSL_NO_OCSP) && !LIBRESSL_IN_USE &&                           \
+    OPENSSL_VERSION_NUMBER >= 0x10002000L
+  int rv;
+
+  STACK_OF(X509) * chain_certs;
+  SSL_CTX_get0_chain_certs(ssl_ctx, &chain_certs);
+
+  auto resp = d2i_OCSP_RESPONSE(nullptr, &ocsp_resp, ocsp_resplen);
+  if (resp == nullptr) {
+    LOG(ERROR) << "d2i_OCSP_RESPONSE failed";
+    return -1;
+  }
+  auto resp_deleter = defer(OCSP_RESPONSE_free, resp);
+
+  if (OCSP_response_status(resp) != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
+    LOG(ERROR) << "OCSP response status is not successful";
+    return -1;
+  }
+
+  ERR_clear_error();
+
+  auto bs = OCSP_response_get1_basic(resp);
+  if (bs == nullptr) {
+    LOG(ERROR) << "OCSP_response_get1_basic failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    return -1;
+  }
+  auto bs_deleter = defer(OCSP_BASICRESP_free, bs);
+
+  auto store = SSL_CTX_get_cert_store(ssl_ctx);
+
+  ERR_clear_error();
+
+  rv = OCSP_basic_verify(bs, chain_certs, store, 0);
+
+  if (rv != 1) {
+    LOG(ERROR) << "OCSP_basic_verify failed: "
+               << ERR_error_string(ERR_get_error(), nullptr);
+    return -1;
+  }
+
+  auto sresp = OCSP_resp_get0(bs, 0);
+  if (sresp == nullptr) {
+    LOG(ERROR) << "OCSP response verification failed: no single response";
+    return -1;
+  }
+
+#  if OPENSSL_1_1_API
+  auto certid = OCSP_SINGLERESP_get0_id(sresp);
+#  else  // !OPENSSL_1_1_API
+  auto certid = sresp->certId;
+#  endif // !OPENSSL_1_1_API
+  assert(certid != nullptr);
+
+  ASN1_INTEGER *serial;
+  rv = OCSP_id_get0_info(nullptr, nullptr, nullptr, &serial,
+                         const_cast<OCSP_CERTID *>(certid));
+  if (rv != 1) {
+    LOG(ERROR) << "OCSP_id_get0_info failed";
+    return -1;
+  }
+
+  if (serial == nullptr) {
+    LOG(ERROR) << "OCSP response does not contain serial number";
+    return -1;
+  }
+
+  auto cert = SSL_CTX_get0_certificate(ssl_ctx);
+  auto cert_serial = X509_get_serialNumber(cert);
+
+  if (ASN1_INTEGER_cmp(cert_serial, serial)) {
+    LOG(ERROR) << "OCSP verification serial numbers do not match";
+    return -1;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    LOG(INFO) << "OCSP verification succeeded";
+  }
+#endif // !defined(OPENSSL_NO_OCSP) && !LIBRESSL_IN_USE
+       // && OPENSSL_VERSION_NUMBER >= 0x10002000L
+
+  return 0;
+}
+
+ssize_t get_x509_fingerprint(uint8_t *dst, size_t dstlen, const X509 *x,
+                             const EVP_MD *md) {
+  unsigned int len = dstlen;
+  if (X509_digest(x, md, dst, &len) != 1) {
+    return -1;
+  }
+  return len;
+}
+
+namespace {
+StringRef get_x509_name(BlockAllocator &balloc, X509_NAME *nm) {
+  auto b = BIO_new(BIO_s_mem());
+  if (!b) {
+    return StringRef{};
+  }
+
+  auto b_deleter = defer(BIO_free, b);
+
+  // Not documented, but it seems that X509_NAME_print_ex returns the
+  // number of bytes written into b.
+  auto slen = X509_NAME_print_ex(b, nm, 0, XN_FLAG_RFC2253);
+  if (slen <= 0) {
+    return StringRef{};
+  }
+
+  auto iov = make_byte_ref(balloc, slen + 1);
+  BIO_read(b, iov.base, slen);
+  iov.base[slen] = '\0';
+  return StringRef{iov.base, static_cast<size_t>(slen)};
+}
+} // namespace
+
+StringRef get_x509_subject_name(BlockAllocator &balloc, X509 *x) {
+  return get_x509_name(balloc, X509_get_subject_name(x));
+}
+
+StringRef get_x509_issuer_name(BlockAllocator &balloc, X509 *x) {
+  return get_x509_name(balloc, X509_get_issuer_name(x));
+}
+
+#ifdef WORDS_BIGENDIAN
+#  define bswap64(N) (N)
+#else /* !WORDS_BIGENDIAN */
+#  define bswap64(N)                                                           \
+    ((uint64_t)(ntohl((uint32_t)(N))) << 32 | ntohl((uint32_t)((N) >> 32)))
+#endif /* !WORDS_BIGENDIAN */
+
+StringRef get_x509_serial(BlockAllocator &balloc, X509 *x) {
+  auto sn = X509_get_serialNumber(x);
+  auto bn = BN_new();
+  auto bn_d = defer(BN_free, bn);
+  if (!ASN1_INTEGER_to_BN(sn, bn) || BN_num_bytes(bn) > 20) {
+    return StringRef{};
+  }
+
+  std::array<uint8_t, 20> b;
+  auto n = BN_bn2bin(bn, b.data());
+  assert(n <= 20);
+
+  return util::format_hex(balloc, StringRef{b.data(), static_cast<size_t>(n)});
+}
+
+namespace {
+// Performs conversion from |at| to time_t.  The result is stored in
+// |t|.  This function returns 0 if it succeeds, or -1.
+int time_t_from_asn1_time(time_t &t, const ASN1_TIME *at) {
+  int rv;
+
+#if OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL)
+  struct tm tm;
+  rv = ASN1_TIME_to_tm(at, &tm);
+  if (rv != 1) {
+    return -1;
+  }
+
+  t = nghttp2_timegm(&tm);
+#else // !(OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL))
+  auto b = BIO_new(BIO_s_mem());
+  if (!b) {
+    return -1;
+  }
+
+  auto bio_deleter = defer(BIO_free, b);
+
+  rv = ASN1_TIME_print(b, at);
+  if (rv != 1) {
+    return -1;
+  }
+
+#  ifdef OPENSSL_IS_BORINGSSL
+  char *s;
+#  else
+  unsigned char *s;
+#  endif
+  auto slen = BIO_get_mem_data(b, &s);
+  auto tt = util::parse_openssl_asn1_time_print(
+      StringRef{s, static_cast<size_t>(slen)});
+  if (tt == 0) {
+    return -1;
+  }
+
+  t = tt;
+#endif // !(OPENSSL_1_1_1_API && !defined(OPENSSL_IS_BORINGSSL))
+
+  return 0;
+}
+} // namespace
+
+int get_x509_not_before(time_t &t, X509 *x) {
+#if OPENSSL_1_1_API
+  auto at = X509_get0_notBefore(x);
+#else  // !OPENSSL_1_1_API
+  auto at = X509_get_notBefore(x);
+#endif // !OPENSSL_1_1_API
+  if (!at) {
+    return -1;
+  }
+
+  return time_t_from_asn1_time(t, at);
+}
+
+int get_x509_not_after(time_t &t, X509 *x) {
+#if OPENSSL_1_1_API
+  auto at = X509_get0_notAfter(x);
+#else  // !OPENSSL_1_1_API
+  auto at = X509_get_notAfter(x);
+#endif // !OPENSSL_1_1_API
+  if (!at) {
+    return -1;
+  }
+
+  return time_t_from_asn1_time(t, at);
+}
+
+} // namespace tls
+
+} // namespace shrpx