fixup! nghttpx: Send nghttpx-0rtt-uniq header if request is replayable

The incoming nghttpx-0rtt-uniq header fields from inbound client are
stripped by default.  Use --no-strip-incoming-nghttpx-0rtt-uniq in
order not to strip them.

genheaderfunc.py

@@ -31,6 +31,7 @@ HEADERS = [
     "user-agent",
     "date",
     "content-type",
+    "nghttpx-0rtt-uniq",
     # disallowed h1 headers
     'connection',
     'keep-alive',

gennghttpxfun.py

@@ -168,6 +168,11 @@ OPTIONS = [
     "no-strip-incoming-x-forwarded-proto",
     "ocsp-startup",
     "no-verify-ocsp",
+    "tls-anti-replay-memcached",
+    "tls-anti-replay-memcached-cert-file",
+    "tls-anti-replay-memcached-private-key-file",
+    "tls-anti-replay-memcached-address-family",
+    "no-strip-incoming-nghttpx-0rtt-uniq",
 ]
 
 LOGVARS = [

src/http2.cc

@@ -434,6 +434,11 @@ void copy_headers_to_nva_internal(std::vector<nghttp2_nv> &nva,
       kv = &(*it_via);
       it_via = it;
       break;
+    case HD_NGHTTPX_0RTT_UNIQ:
+      if (flags & HDOP_STRIP_NGHTTPX_ZERO_RTT_UNIQ) {
+        continue;
+      }
+      break;
     }
     nva.push_back(
         make_nv_internal(kv->name, kv->value, kv->no_index, nv_flags));
@@ -920,6 +925,11 @@ int lookup_token(const uint8_t *name, size_t namelen) {
         return HD_X_FORWARDED_PROTO;
       }
       break;
+    case 'q':
+      if (util::streq_l("nghttpx-0rtt-uni", name, 16)) {
+        return HD_NGHTTPX_0RTT_UNIQ;
+      }
+      break;
     }
     break;
   }

src/http2.h

@@ -203,9 +203,13 @@ enum HeaderBuildOp {
   // Via header fields must be stripped.  If this flag is not set, all
   // Via header fields other than last one are added.
   HDOP_STRIP_VIA = 1 << 3,
+  // nghttpx-0rtt-uniq header fields must be stripped.  If this flag
+  // is not set, all nghttpx-0rtt-uniq header fields are added.
+  HDOP_STRIP_NGHTTPX_ZERO_RTT_UNIQ = 1 << 4,
   // Strip above all header fields.
   HDOP_STRIP_ALL = HDOP_STRIP_FORWARDED | HDOP_STRIP_X_FORWARDED_FOR |
-                   HDOP_STRIP_X_FORWARDED_PROTO | HDOP_STRIP_VIA,
+                   HDOP_STRIP_X_FORWARDED_PROTO | HDOP_STRIP_VIA |
+                   HDOP_STRIP_NGHTTPX_ZERO_RTT_UNIQ,
 };
 
 // Appends headers in |headers| to |nv|.  |headers| must be indexed
@@ -312,6 +316,7 @@ enum {
   HD_KEEP_ALIVE,
   HD_LINK,
   HD_LOCATION,
+  HD_NGHTTPX_0RTT_UNIQ,
   HD_PROXY_CONNECTION,
   HD_SERVER,
   HD_TE,

src/shrpx.cc

@@ -1438,6 +1438,12 @@ void fill_default_config(Config *config) {
       memcachedconf.family = AF_UNSPEC;
     }
 
+    auto &anti_replayconf = tlsconf.anti_replay;
+    {
+      auto &memcachedconf = anti_replayconf.memcached;
+      memcachedconf.family = AF_UNSPEC;
+    }
+
     ticketconf.cipher = EVP_aes_128_cbc();
   }
 
@@ -1480,6 +1486,7 @@ void fill_default_config(Config *config) {
   httpconf.max_requests = std::numeric_limits<size_t>::max();
   httpconf.xfp.add = true;
   httpconf.xfp.strip_incoming = true;
+  httpconf.zero_rtt_uniq.strip_incoming = true;
 
   auto &http2conf = config->http2;
   {
@@ -2284,6 +2291,25 @@ SSL/TLS:
   --tls-session-cache-memcached-private-key-file=<PATH>
               Path to client private  key for memcached connections to
               store session cache.
+  --tls-anti-replay-memcached=<HOST>,<PORT>[;tls]
+              Specify address of memcached server to store ClientHello
+              to avoid  0-RTT early data replay.   This enables shared
+              storage between multiple nghttpx instances.  Optionally,
+              memcached  connection  can  be  encrypted  with  TLS  by
+              specifying "tls" parameter.
+  --tls-anti-replay-memcached-address-family=(auto|IPv4|IPv6)
+              Specify address family of memcached connections to store
+              ClientHello to avoid 0-RTT early data replay.  If "auto"
+              is given, both IPv4 and  IPv6 are considered.  If "IPv4"
+              is given, only IPv4 address is considered.  If "IPv6" is
+              given, only IPv6 address is considered.
+              Default: auto
+  --tls-anti-replay-memcached-cert-file=<PATH>
+              Path to client certificate  for memcached connections to
+              store ClientHello to avoid 0-RTT early data replay.
+  --tls-anti-replay-memcached-private-key-file=<PATH>
+              Path to client private  key for memcached connections to
+              store ClientHello to avoid 0-RTT early data replay.
   --tls-dyn-rec-warmup-threshold=<SIZE>
               Specify the  threshold size for TLS  dynamic record size
               behaviour.  During  a TLS  session, after  the threshold
@@ -2590,6 +2616,9 @@ HTTP:
               Default: obfuscated
   --no-via    Don't append to  Via header field.  If  Via header field
               is received, it is left unaltered.
+  --no-strip-incoming-nghttpx-0rtt-uniq
+              Don't strip nghttpx-0rtt-uniq  header field from inbound
+              client requests.
   --no-location-rewrite
               Don't  rewrite location  header field  in default  mode.
               When --http2-proxy  is used, location header  field will
@@ -2995,6 +3024,26 @@ int process_options(Config *config,
     }
   }
 
+  {
+    auto &memcachedconf = tlsconf.anti_replay.memcached;
+    if (!memcachedconf.host.empty()) {
+      auto hostport = util::make_hostport(StringRef{memcachedconf.host},
+                                          memcachedconf.port);
+      if (resolve_hostname(&memcachedconf.addr, memcachedconf.host.c_str(),
+                           memcachedconf.port, memcachedconf.family) == -1) {
+        LOG(FATAL) << "Resolving memcached address for TLS anti-replay failed: "
+                   << hostport;
+        return -1;
+      }
+      LOG(NOTICE) << "Memcached address for TLS anti-replay: " << hostport
+                  << " -> " << util::to_numeric_addr(&memcachedconf.addr);
+      if (memcachedconf.tls) {
+        LOG(NOTICE) << "Connection to memcached for TLS anti-replay will be "
+                       "encrypted by TLS";
+      }
+    }
+  }
+
   if (config->rlimit_nofile) {
     struct rlimit lim = {static_cast<rlim_t>(config->rlimit_nofile),
                          static_cast<rlim_t>(config->rlimit_nofile)};
@@ -3404,6 +3453,16 @@ int main(int argc, char **argv) {
         {SHRPX_OPT_NO_STRIP_INCOMING_X_FORWARDED_PROTO.c_str(), no_argument,
          &flag, 158},
         {SHRPX_OPT_SINGLE_PROCESS.c_str(), no_argument, &flag, 159},
+        {SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED.c_str(), required_argument, &flag,
+         160},
+        {SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_ADDRESS_FAMILY.c_str(),
+         required_argument, &flag, 161},
+        {SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_CERT_FILE.c_str(),
+         required_argument, &flag, 162},
+        {SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_PRIVATE_KEY_FILE.c_str(),
+         required_argument, &flag, 163},
+        {SHRPX_OPT_NO_STRIP_INCOMING_NGHTTPX_0RTT_UNIQ.c_str(), no_argument,
+         &flag, 164},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -4165,6 +4224,32 @@ int main(int argc, char **argv) {
         cmdcfgs.emplace_back(SHRPX_OPT_SINGLE_PROCESS,
                              StringRef::from_lit("yes"));
         break;
+      case 160:
+        // --tls-anti-replay-memcached
+        cmdcfgs.emplace_back(SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED,
+                             StringRef{optarg});
+        break;
+      case 161:
+        // --tls-anti-replay-memcached-address-family
+        cmdcfgs.emplace_back(SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_ADDRESS_FAMILY,
+                             StringRef{optarg});
+        break;
+      case 162:
+        // --tls-anti-replay-memcached-cert-file
+        cmdcfgs.emplace_back(SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_CERT_FILE,
+                             StringRef{optarg});
+        break;
+      case 163:
+        // --tls-anti-replay-memcached-private-key-file
+        cmdcfgs.emplace_back(
+            SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_PRIVATE_KEY_FILE,
+            StringRef{optarg});
+        break;
+      case 164:
+        // --no-strip-incoming-nghttpx-0rtt-uniq
+        cmdcfgs.emplace_back(SHRPX_OPT_NO_STRIP_INCOMING_NGHTTPX_0RTT_UNIQ,
+                             StringRef::from_lit("yes"));
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -2072,6 +2072,11 @@ int option_lookup_token(const char *name, size_t namelen) {
     break;
   case 25:
     switch (name[24]) {
+    case 'd':
+      if (util::strieq_l("tls-anti-replay-memcache", name, 24)) {
+        return SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED;
+      }
+      break;
     case 'e':
       if (util::strieq_l("backend-http2-window-siz", name, 24)) {
         return SHRPX_OPTID_BACKEND_HTTP2_WINDOW_SIZE;
@@ -2255,12 +2260,20 @@ int option_lookup_token(const char *name, size_t namelen) {
       if (util::strieq_l("frontend-http2-optimize-window-siz", name, 34)) {
         return SHRPX_OPTID_FRONTEND_HTTP2_OPTIMIZE_WINDOW_SIZE;
       }
+      if (util::strieq_l("tls-anti-replay-memcached-cert-fil", name, 34)) {
+        return SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_CERT_FILE;
+      }
       break;
     case 'o':
       if (util::strieq_l("no-strip-incoming-x-forwarded-prot", name, 34)) {
         return SHRPX_OPTID_NO_STRIP_INCOMING_X_FORWARDED_PROTO;
       }
       break;
+    case 'q':
+      if (util::strieq_l("no-strip-incoming-nghttpx-0rtt-uni", name, 34)) {
+        return SHRPX_OPTID_NO_STRIP_INCOMING_NGHTTPX_0RTT_UNIQ;
+      }
+      break;
     case 'r':
       if (util::strieq_l("frontend-http2-dump-response-heade", name, 34)) {
         return SHRPX_OPTID_FRONTEND_HTTP2_DUMP_RESPONSE_HEADER;
@@ -2338,6 +2351,11 @@ int option_lookup_token(const char *name, size_t namelen) {
         return SHRPX_OPTID_BACKEND_HTTP2_ENCODER_DYNAMIC_TABLE_SIZE;
       }
       break;
+    case 'y':
+      if (util::strieq_l("tls-anti-replay-memcached-address-famil", name, 39)) {
+        return SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_ADDRESS_FAMILY;
+      }
+      break;
     }
     break;
   case 41:
@@ -2364,6 +2382,12 @@ int option_lookup_token(const char *name, size_t namelen) {
     break;
   case 42:
     switch (name[41]) {
+    case 'e':
+      if (util::strieq_l("tls-anti-replay-memcached-private-key-fil", name,
+                         41)) {
+        return SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_PRIVATE_KEY_FILE;
+      }
+      break;
     case 'y':
       if (util::strieq_l("tls-session-cache-memcached-address-famil", name,
                          41)) {
@@ -3153,7 +3177,8 @@ int parse_config(Config *config, int optid, const StringRef &opt,
 
     return 0;
   case SHRPX_OPTID_TLS_SESSION_CACHE_MEMCACHED:
-  case SHRPX_OPTID_TLS_TICKET_KEY_MEMCACHED: {
+  case SHRPX_OPTID_TLS_TICKET_KEY_MEMCACHED:
+  case SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED: {
     auto addr_end = std::find(std::begin(optarg), std::end(optarg), ';');
     auto src_params = StringRef{addr_end, std::end(optarg)};
 
@@ -3183,6 +3208,13 @@ int parse_config(Config *config, int optid, const StringRef &opt,
       memcachedconf.tls = params.tls;
       break;
     }
+    case SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED: {
+      auto &memcachedconf = config->tls.anti_replay.memcached;
+      memcachedconf.host = make_string_ref(config->balloc, StringRef{host});
+      memcachedconf.port = port;
+      memcachedconf.tls = params.tls;
+      break;
+    }
     };
 
     return 0;
@@ -3330,6 +3362,16 @@ int parse_config(Config *config, int optid, const StringRef &opt,
     config->tls.ticket.memcached.private_key_file =
         make_string_ref(config->balloc, optarg);
 
+    return 0;
+  case SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_CERT_FILE:
+    config->tls.anti_replay.memcached.cert_file =
+        make_string_ref(config->balloc, optarg);
+
+    return 0;
+  case SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_PRIVATE_KEY_FILE:
+    config->tls.anti_replay.memcached.private_key_file =
+        make_string_ref(config->balloc, optarg);
+
     return 0;
   case SHRPX_OPTID_TLS_TICKET_KEY_MEMCACHED_ADDRESS_FAMILY:
     return parse_address_family(&config->tls.ticket.memcached.family, opt,
@@ -3337,6 +3379,9 @@ int parse_config(Config *config, int optid, const StringRef &opt,
   case SHRPX_OPTID_TLS_SESSION_CACHE_MEMCACHED_ADDRESS_FAMILY:
     return parse_address_family(&config->tls.session_cache.memcached.family,
                                 opt, optarg);
+  case SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_ADDRESS_FAMILY:
+    return parse_address_family(&config->tls.anti_replay.memcached.family, opt,
+                                optarg);
   case SHRPX_OPTID_BACKEND_ADDRESS_FAMILY:
     return parse_address_family(&config->conn.downstream->family, opt, optarg);
   case SHRPX_OPTID_FRONTEND_HTTP2_MAX_CONCURRENT_STREAMS:
@@ -3550,6 +3595,10 @@ int parse_config(Config *config, int optid, const StringRef &opt,
   case SHRPX_OPTID_NO_VERIFY_OCSP:
     config->tls.ocsp.no_verify = util::strieq_l("yes", optarg);
 
+    return 0;
+  case SHRPX_OPTID_NO_STRIP_INCOMING_NGHTTPX_0RTT_UNIQ:
+    config->http.zero_rtt_uniq.strip_incoming = !util::strieq_l("yes", optarg);
+
     return 0;
   case SHRPX_OPTID_CONF:
     LOG(WARN) << "conf: ignored";

src/shrpx_config.h

@@ -343,6 +343,16 @@ constexpr auto SHRPX_OPT_NO_STRIP_INCOMING_X_FORWARDED_PROTO =
     StringRef::from_lit("no-strip-incoming-x-forwarded-proto");
 constexpr auto SHRPX_OPT_OCSP_STARTUP = StringRef::from_lit("ocsp-startup");
 constexpr auto SHRPX_OPT_NO_VERIFY_OCSP = StringRef::from_lit("no-verify-ocsp");
+constexpr auto SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED =
+    StringRef::from_lit("tls-anti-replay-memcached");
+constexpr auto SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_CERT_FILE =
+    StringRef::from_lit("tls-anti-replay-memcached-cert-file");
+constexpr auto SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_PRIVATE_KEY_FILE =
+    StringRef::from_lit("tls-anti-replay-memcached-private-key-file");
+constexpr auto SHRPX_OPT_TLS_ANTI_REPLAY_MEMCACHED_ADDRESS_FAMILY =
+    StringRef::from_lit("tls-anti-replay-memcached-address-family");
+constexpr auto SHRPX_OPT_NO_STRIP_INCOMING_NGHTTPX_0RTT_UNIQ =
+    StringRef::from_lit("no-strip-incoming-nghttpx-0rtt-uniq");
 
 constexpr size_t SHRPX_OBFUSCATED_NODE_LENGTH = 8;
 
@@ -577,6 +587,23 @@ struct TLSConfig {
     } memcached;
   } session_cache;
 
+  struct {
+    struct {
+      Address addr;
+      uint16_t port;
+      // Hostname of memcached server.  This is also used as SNI field
+      // if TLS is enabled.
+      StringRef host;
+      // Client private key and certificate for authentication
+      StringRef private_key_file;
+      StringRef cert_file;
+      // Address family of memcached connection.  One of either
+      // AF_INET, AF_INET6 or AF_UNSPEC.
+      int family;
+      bool tls;
+    } memcached;
+  } anti_replay;
+
   // Dynamic record sizing configurations
   struct {
     size_t warmup_threshold;
@@ -679,6 +706,9 @@ struct HttpConfig {
     bool add;
     bool strip_incoming;
   } xfp;
+  struct {
+    bool strip_incoming;
+  } zero_rtt_uniq;
   std::vector<AltSvc> altsvcs;
   std::vector<ErrorPage> error_pages;
   HeaderRefs add_request_headers;
@@ -1071,6 +1101,7 @@ enum {
   SHRPX_OPTID_NO_OCSP,
   SHRPX_OPTID_NO_SERVER_PUSH,
   SHRPX_OPTID_NO_SERVER_REWRITE,
+  SHRPX_OPTID_NO_STRIP_INCOMING_NGHTTPX_0RTT_UNIQ,
   SHRPX_OPTID_NO_STRIP_INCOMING_X_FORWARDED_PROTO,
   SHRPX_OPTID_NO_VERIFY_OCSP,
   SHRPX_OPTID_NO_VIA,
@@ -1097,6 +1128,10 @@ enum {
   SHRPX_OPTID_STRIP_INCOMING_X_FORWARDED_FOR,
   SHRPX_OPTID_SUBCERT,
   SHRPX_OPTID_SYSLOG_FACILITY,
+  SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED,
+  SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_ADDRESS_FAMILY,
+  SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_CERT_FILE,
+  SHRPX_OPTID_TLS_ANTI_REPLAY_MEMCACHED_PRIVATE_KEY_FILE,
   SHRPX_OPTID_TLS_DYN_REC_IDLE_TIMEOUT,
   SHRPX_OPTID_TLS_DYN_REC_WARMUP_THRESHOLD,
   SHRPX_OPTID_TLS_MAX_PROTO_VERSION,

src/shrpx_connection.cc

@@ -38,7 +38,6 @@
 #include "shrpx_log.h"
 #include "memchunk.h"
 #include "util.h"
-#include "ssl_compat.h"
 
 using namespace nghttp2;
 
@@ -60,7 +59,8 @@ Connection::Connection(struct ev_loop *loop, int fd, SSL *ssl,
                        IOCb readcb, TimerCb timeoutcb, void *data,
                        size_t tls_dyn_rec_warmup_threshold,
                        ev_tstamp tls_dyn_rec_idle_timeout, shrpx_proto proto)
-    : tls{DefaultMemchunks(mcpool), DefaultPeekMemchunks(mcpool)},
+    : tls{DefaultMemchunks(mcpool), DefaultPeekMemchunks(mcpool),
+          DefaultMemchunks(mcpool)},
       wlimit(loop, &wev, write_limit.rate, write_limit.burst),
       rlimit(loop, &rev, read_limit.rate, read_limit.burst, this),
       loop(loop),
@@ -92,7 +92,15 @@ Connection::Connection(struct ev_loop *loop, int fd, SSL *ssl,
   }
 }
 
-Connection::~Connection() { disconnect(); }
+Connection::~Connection() {
+  disconnect();
+
+#if OPENSSL_1_1_1_API
+  if (tls.ch_md_ctx) {
+    EVP_MD_CTX_free(tls.ch_md_ctx);
+  }
+#endif // OPENSSL_1_1_1_API
+}
 
 void Connection::disconnect() {
   if (tls.ssl) {
@@ -110,20 +118,34 @@ void Connection::disconnect() {
       tls.cached_session_lookup_req = nullptr;
     }
 
+    if (tls.anti_replay_req) {
+      tls.anti_replay_req->canceled = true;
+      tls.anti_replay_req = nullptr;
+    }
+
     SSL_shutdown(tls.ssl);
     SSL_free(tls.ssl);
     tls.ssl = nullptr;
 
+#if OPENSSL_1_1_1_API
+    if (tls.ch_md_ctx) {
+      EVP_MD_CTX_reset(tls.ch_md_ctx);
+    }
+#endif // OPENSSL_1_1_1_API
+
     tls.wbuf.reset();
     tls.rbuf.reset();
     tls.last_write_idle = 0.;
     tls.warmup_writelen = 0;
     tls.last_writelen = 0;
     tls.last_readlen = 0;
-    tls.handshake_state = 0;
+    tls.handshake_state = TLS_CONN_NORMAL;
     tls.initial_handshake_done = false;
     tls.reneg_started = false;
     tls.sct_requested = false;
+    tls.early_data_finish = false;
+    tls.early_cb_called = false;
+    tls.postpone_early_data = false;
   }
 
   if (fd != -1) {
@@ -141,11 +163,23 @@ void Connection::disconnect() {
   wlimit.stopw();
 }
 
-void Connection::prepare_client_handshake() { SSL_set_connect_state(tls.ssl); }
+void Connection::prepare_client_handshake() {
+  SSL_set_connect_state(tls.ssl);
+  // This prevents SSL_read_early_data from being called.
+  tls.early_data_finish = true;
+}
 
 void Connection::prepare_server_handshake() {
   SSL_set_accept_state(tls.ssl);
   tls.server_handshake = true;
+
+#if OPENSSL_1_1_1_API
+  if (!tls.ch_md_ctx) {
+    tls.ch_md_ctx = EVP_MD_CTX_new();
+  }
+
+  EVP_DigestInit_ex(tls.ch_md_ctx, EVP_sha256(), nullptr);
+#endif // OPENSSL_1_1_1_API
 }
 
 // BIO implementation is inspired by openldap implementation:
@@ -219,7 +253,19 @@ int shrpx_bio_read(BIO *b, char *buf, int len) {
     return -1;
   }
 
-  return rbuf.remove(buf, len);
+  len = rbuf.remove(buf, len);
+
+  if (conn->tls.early_cb_called) {
+    return len;
+  }
+
+#if OPENSSL_1_1_1_API
+  if (EVP_DigestUpdate(conn->tls.ch_md_ctx, buf, len) == 0) {
+    return -1;
+  }
+#endif // OPENSSL_1_1_1_API
+
+  return len;
 }
 } // namespace
 
@@ -327,8 +373,9 @@ int Connection::tls_handshake() {
   wlimit.stopw();
   ev_timer_stop(loop, &wt);
 
+  std::array<uint8_t, 16_k> buf;
+
   if (ev_is_active(&rev)) {
-    std::array<uint8_t, 8_k> buf;
     auto nread = read_clear(buf.data(), buf.size());
     if (nread < 0) {
       if (LOG_ENABLED(INFO)) {
@@ -348,6 +395,7 @@ int Connection::tls_handshake() {
 
   switch (tls.handshake_state) {
   case TLS_CONN_WAIT_FOR_SESSION_CACHE:
+  case TLS_CONN_WAIT_FOR_ANTI_REPLAY:
     return SHRPX_ERR_INPROGRESS;
   case TLS_CONN_GOT_SESSION_CACHE: {
     // Use the same trick invented by @kazuho in h2o project.
@@ -381,9 +429,73 @@ int Connection::tls_handshake() {
     break;
   }
 
+  int rv;
+
   ERR_clear_error();
 
-  auto rv = SSL_do_handshake(tls.ssl);
+#if OPENSSL_1_1_1_API
+  if (!tls.server_handshake || tls.early_data_finish) {
+    rv = SSL_do_handshake(tls.ssl);
+  } else {
+    for (;;) {
+      size_t nread;
+
+      rv = SSL_read_early_data(tls.ssl, buf.data(), buf.size(), &nread);
+      if (rv == SSL_READ_EARLY_DATA_ERROR) {
+        if (SSL_get_error(tls.ssl, rv) == SSL_ERROR_WANT_CLIENT_HELLO_CB) {
+          if (LOG_ENABLED(INFO)) {
+            LOG(INFO)
+                << "tls: early_cb returns negative return value; handshake "
+                   "interrupted";
+          }
+          break;
+        }
+
+        // If we have early data, and server sends ServerHello, assume
+        // that handshake is completed in server side, and start
+        // processing request.  If we don't exit handshake code here,
+        // server waits for EndOfEarlyData and Finished message from
+        // client, which voids the purpose of 0-RTT data.  The left
+        // over of handshake is done through write_tls or read_tls.
+        if (!tls.postpone_early_data &&
+            (tls.handshake_state == TLS_CONN_WRITE_STARTED ||
+             tls.wbuf.rleft()) &&
+            tls.earlybuf.rleft()) {
+          rv = 1;
+        }
+
+        break;
+      }
+
+      if (LOG_ENABLED(INFO)) {
+        LOG(INFO) << "tls: read early data " << nread << " bytes";
+      }
+
+      tls.earlybuf.append(buf.data(), nread);
+
+      if (rv == SSL_READ_EARLY_DATA_FINISH) {
+        if (LOG_ENABLED(INFO)) {
+          LOG(INFO) << "tls: read all early data; total "
+                    << tls.earlybuf.rleft() << " bytes";
+        }
+        tls.early_data_finish = true;
+        // The same reason stated above.
+        if (!tls.postpone_early_data &&
+            (tls.handshake_state == TLS_CONN_WRITE_STARTED ||
+             tls.wbuf.rleft()) &&
+            tls.earlybuf.rleft()) {
+          rv = 1;
+        } else {
+          ERR_clear_error();
+          rv = SSL_do_handshake(tls.ssl);
+        }
+        break;
+      }
+    }
+  }
+#else  // !OPENSSL_1_1_1_API
+  rv = SSL_do_handshake(tls.ssl);
+#endif // !OPENSSL_1_1_1_API
 
   if (rv <= 0) {
     auto err = SSL_get_error(tls.ssl, rv);
@@ -397,6 +509,9 @@ int Connection::tls_handshake() {
       }
       break;
     case SSL_ERROR_WANT_WRITE:
+#if OPENSSL_1_1_1_API
+    case SSL_ERROR_WANT_CLIENT_HELLO_CB:
+#endif // OPENSSL_1_1_1_API
       break;
     case SSL_ERROR_SSL:
       if (LOG_ENABLED(INFO)) {
@@ -412,7 +527,8 @@ int Connection::tls_handshake() {
     }
   }
 
-  if (tls.handshake_state == TLS_CONN_WAIT_FOR_SESSION_CACHE) {
+  if (tls.handshake_state == TLS_CONN_WAIT_FOR_SESSION_CACHE ||
+      tls.handshake_state == TLS_CONN_WAIT_FOR_ANTI_REPLAY) {
     if (LOG_ENABLED(INFO)) {
       LOG(INFO) << "tls: handshake is still in progress";
     }
@@ -619,7 +735,21 @@ ssize_t Connection::write_tls(const void *data, size_t len) {
 
   ERR_clear_error();
 
+#if OPENSSL_1_1_1_API
+  int rv;
+  if (SSL_is_init_finished(tls.ssl)) {
+    rv = SSL_write(tls.ssl, data, len);
+  } else {
+    size_t nwrite;
+    rv = SSL_write_early_data(tls.ssl, data, len, &nwrite);
+    // Use the same semantics with SSL_write.
+    if (rv == 1) {
+      rv = nwrite;
+    }
+  }
+#else  // !OPENSSL_1_1_1_API
   auto rv = SSL_write(tls.ssl, data, len);
+#endif // !OPENSSL_1_1_1_API
 
   if (rv <= 0) {
     auto err = SSL_get_error(tls.ssl, rv);
@@ -654,6 +784,14 @@ ssize_t Connection::write_tls(const void *data, size_t len) {
 }
 
 ssize_t Connection::read_tls(void *data, size_t len) {
+  ERR_clear_error();
+
+#if OPENSSL_1_1_1_API
+  if (tls.earlybuf.rleft()) {
+    return tls.earlybuf.remove(data, len);
+  }
+#endif // OPENSSL_1_1_1_API
+
   // SSL_read requires the same arguments (buf pointer and its
   // length) on SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE.
   // rlimit_.avail() or rlimit_.avail() may return different length
@@ -671,7 +809,46 @@ ssize_t Connection::read_tls(void *data, size_t len) {
     tls.last_readlen = 0;
   }
 
-  ERR_clear_error();
+#if OPENSSL_1_1_1_API
+  if (!tls.early_data_finish) {
+    // TLSv1.3 handshake is still going on.
+    size_t nread;
+    auto rv = SSL_read_early_data(tls.ssl, data, len, &nread);
+    if (rv == SSL_READ_EARLY_DATA_ERROR) {
+      auto err = SSL_get_error(tls.ssl, rv);
+      switch (err) {
+      case SSL_ERROR_WANT_READ:
+        tls.last_readlen = len;
+        return 0;
+      case SSL_ERROR_SSL:
+        if (LOG_ENABLED(INFO)) {
+          LOG(INFO) << "SSL_read: "
+                    << ERR_error_string(ERR_get_error(), nullptr);
+        }
+        return SHRPX_ERR_NETWORK;
+      default:
+        if (LOG_ENABLED(INFO)) {
+          LOG(INFO) << "SSL_read: SSL_get_error returned " << err;
+        }
+        return SHRPX_ERR_NETWORK;
+      }
+    }
+
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "tls: read early data " << nread << " bytes";
+    }
+
+    if (rv == SSL_READ_EARLY_DATA_FINISH) {
+      if (LOG_ENABLED(INFO)) {
+        LOG(INFO) << "tls: read all early data";
+      }
+      tls.early_data_finish = true;
+      // We may have stopped write watcher in write_tls.
+      wlimit.startw();
+    }
+    return nread;
+  }
+#endif // OPENSSL_1_1_1_API
 
   auto rv = SSL_read(tls.ssl, data, len);
 

src/shrpx_connection.h

@@ -32,10 +32,12 @@
 #include <ev.h>
 
 #include <openssl/ssl.h>
+#include <openssl/evp.h>
 
 #include "shrpx_rate_limit.h"
 #include "shrpx_error.h"
 #include "memchunk.h"
+#include "ssl_compat.h"
 
 namespace shrpx {
 
@@ -50,16 +52,26 @@ enum {
   TLS_CONN_WAIT_FOR_SESSION_CACHE,
   TLS_CONN_GOT_SESSION_CACHE,
   TLS_CONN_CANCEL_SESSION_CACHE,
+  TLS_CONN_WAIT_FOR_ANTI_REPLAY,
   TLS_CONN_WRITE_STARTED,
 };
 
 struct TLSConnection {
   DefaultMemchunks wbuf;
   DefaultPeekMemchunks rbuf;
+  // Stores TLSv1.3 early data.
+  DefaultMemchunks earlybuf;
+  // Message digest of ClientHello in hex string.
+  StringRef ch_hex_md;
   SSL *ssl;
   SSL_SESSION *cached_session;
   MemcachedRequest *cached_session_lookup_req;
   tls::TLSSessionCache *client_session_cache;
+#if OPENSSL_1_1_1_API
+  // Message digest context to calculate ClientHello for anti-replay.
+  EVP_MD_CTX *ch_md_ctx;
+#endif // !OPENSSL_1_1_1_API
+  MemcachedRequest *anti_replay_req;
   ev_tstamp last_write_idle;
   size_t warmup_writelen;
   // length passed to SSL_write and SSL_read last time.  This is
@@ -74,6 +86,17 @@ struct TLSConnection {
   // true if ssl is initialized as server, and client requested
   // signed_certificate_timestamp extension.
   bool sct_requested;
+  // true if TLSv1.3 early data has been completely received.  Since
+  // SSL_read_early_data acts like SSL_do_handshake, this field may be
+  // true even if the negotiated TLS version is TLSv1.2 or earlier.
+  // This value is also true if this is client side connection for
+  // convenience.
+  bool early_data_finish;
+  // true if early_cb gets called.
+  bool early_cb_called;
+  // true if processing early data should be postponed until handshake
+  // finishes.
+  bool postpone_early_data;
 };
 
 struct TCPHint {

src/shrpx_connection_handler.cc

@@ -235,9 +235,24 @@ int ConnectionHandler::create_single_worker() {
     }
   }
 
+  SSL_CTX *anti_replay_ssl_ctx = nullptr;
+  {
+    auto &memcachedconf = config->tls.anti_replay.memcached;
+
+    if (memcachedconf.tls) {
+      anti_replay_ssl_ctx = tls::create_ssl_client_context(
+#ifdef HAVE_NEVERBLEED
+          nb_.get(),
+#endif // HAVE_NEVERBLEED
+          tlsconf.cacert, memcachedconf.cert_file,
+          memcachedconf.private_key_file, nullptr);
+      all_ssl_ctx_.push_back(anti_replay_ssl_ctx);
+    }
+  }
+
   single_worker_ = make_unique<Worker>(
-      loop_, sv_ssl_ctx, cl_ssl_ctx, session_cache_ssl_ctx, cert_tree_.get(),
-      ticket_keys_, this, config->conn.downstream);
+      loop_, sv_ssl_ctx, cl_ssl_ctx, session_cache_ssl_ctx, anti_replay_ssl_ctx,
+      cert_tree_.get(), ticket_keys_, this, config->conn.downstream);
 #ifdef HAVE_MRUBY
   if (single_worker_->create_mruby_context() != 0) {
     return -1;
@@ -293,12 +308,28 @@ int ConnectionHandler::create_worker_thread(size_t num) {
     }
   }
 
+  SSL_CTX *anti_replay_ssl_ctx = nullptr;
+  {
+    auto &memcachedconf = config->tls.anti_replay.memcached;
+
+    if (memcachedconf.tls) {
+      anti_replay_ssl_ctx = tls::create_ssl_client_context(
+#ifdef HAVE_NEVERBLEED
+          nb_.get(),
+#endif // HAVE_NEVERBLEED
+          tlsconf.cacert, memcachedconf.cert_file,
+          memcachedconf.private_key_file, nullptr);
+      all_ssl_ctx_.push_back(anti_replay_ssl_ctx);
+    }
+  }
+
   for (size_t i = 0; i < num; ++i) {
     auto loop = ev_loop_new(config->ev_loop_flags);
 
-    auto worker = make_unique<Worker>(
-        loop, sv_ssl_ctx, cl_ssl_ctx, session_cache_ssl_ctx, cert_tree_.get(),
-        ticket_keys_, this, config->conn.downstream);
+    auto worker =
+        make_unique<Worker>(loop, sv_ssl_ctx, cl_ssl_ctx, session_cache_ssl_ctx,
+                            anti_replay_ssl_ctx, cert_tree_.get(), ticket_keys_,
+                            this, config->conn.downstream);
 #ifdef HAVE_MRUBY
     if (worker->create_mruby_context() != 0) {
       return -1;

src/shrpx_http2_downstream_connection.cc

@@ -271,7 +271,7 @@ int Http2DownstreamConnection::push_request_headers() {
     num_cookies = downstream_->count_crumble_request_cookie();
   }
 
-  // 9 means:
+  // 10 means:
   // 1. :method
   // 2. :scheme
   // 3. :path
@@ -281,8 +281,9 @@ int Http2DownstreamConnection::push_request_headers() {
   // 7. x-forwarded-proto (optional)
   // 8. te (optional)
   // 9. forwarded (optional)
+  // 10. nghttpx-0rtt-uniq (optional)
   auto nva = std::vector<nghttp2_nv>();
-  nva.reserve(req.fs.headers().size() + 9 + num_cookies +
+  nva.reserve(req.fs.headers().size() + 10 + num_cookies +
               httpconf.add_request_headers.size());
 
   nva.push_back(
@@ -311,11 +312,15 @@ int Http2DownstreamConnection::push_request_headers() {
   auto &fwdconf = httpconf.forwarded;
   auto &xffconf = httpconf.xff;
   auto &xfpconf = httpconf.xfp;
+  auto &zero_rtt_uniqconf = httpconf.zero_rtt_uniq;
 
   uint32_t build_flags =
       (fwdconf.strip_incoming ? http2::HDOP_STRIP_FORWARDED : 0) |
       (xffconf.strip_incoming ? http2::HDOP_STRIP_X_FORWARDED_FOR : 0) |
-      (xfpconf.strip_incoming ? http2::HDOP_STRIP_X_FORWARDED_PROTO : 0);
+      (xfpconf.strip_incoming ? http2::HDOP_STRIP_X_FORWARDED_PROTO : 0) |
+      (zero_rtt_uniqconf.strip_incoming
+           ? http2::HDOP_STRIP_NGHTTPX_ZERO_RTT_UNIQ
+           : 0);
 
   http2::copy_headers_to_nva_nocopy(nva, req.fs.headers(), build_flags);
 
@@ -326,6 +331,15 @@ int Http2DownstreamConnection::push_request_headers() {
   auto upstream = downstream_->get_upstream();
   auto handler = upstream->get_client_handler();
 
+#if OPENSSL_1_1_1_API
+  auto conn = handler->get_connection();
+
+  if (!SSL_is_init_finished(conn->tls.ssl)) {
+    nva.push_back(
+        http2::make_nv_ls_nocopy("nghttpx-0rtt-uniq", conn->tls.ch_hex_md));
+  }
+#endif // OPENSSL_1_1_1_API
+
   auto fwd =
       fwdconf.strip_incoming ? nullptr : req.fs.header(http2::HD_FORWARDED);
 

src/shrpx_http_downstream_connection.cc

@@ -535,11 +535,15 @@ int HttpDownstreamConnection::push_request_headers() {
   auto &fwdconf = httpconf.forwarded;
   auto &xffconf = httpconf.xff;
   auto &xfpconf = httpconf.xfp;
+  auto &zero_rtt_uniqconf = httpconf.zero_rtt_uniq;
 
   uint32_t build_flags =
       (fwdconf.strip_incoming ? http2::HDOP_STRIP_FORWARDED : 0) |
       (xffconf.strip_incoming ? http2::HDOP_STRIP_X_FORWARDED_FOR : 0) |
-      (xfpconf.strip_incoming ? http2::HDOP_STRIP_X_FORWARDED_PROTO : 0);
+      (xfpconf.strip_incoming ? http2::HDOP_STRIP_X_FORWARDED_PROTO : 0) |
+      (zero_rtt_uniqconf.strip_incoming
+           ? http2::HDOP_STRIP_NGHTTPX_ZERO_RTT_UNIQ
+           : 0);
 
   http2::build_http1_headers_from_headers(buf, req.fs.headers(), build_flags);
 
@@ -580,6 +584,16 @@ int HttpDownstreamConnection::push_request_headers() {
   auto upstream = downstream_->get_upstream();
   auto handler = upstream->get_client_handler();
 
+#if OPENSSL_1_1_1_API
+  auto conn = handler->get_connection();
+
+  if (!SSL_is_init_finished(conn->tls.ssl)) {
+    buf->append("Nghttpx-0rtt-uniq: ");
+    buf->append(conn->tls.ch_hex_md);
+    buf->append("\r\n");
+  }
+#endif // OPENSSL_1_1_1_API
+
   auto fwd =
       fwdconf.strip_incoming ? nullptr : req.fs.header(http2::HD_FORWARDED);
 

src/shrpx_rate_limit.cc

@@ -108,8 +108,9 @@ void RateLimit::stopw() {
 }
 
 void RateLimit::handle_tls_pending_read() {
-  if (!conn_ || !conn_->tls.ssl ||
-      (SSL_pending(conn_->tls.ssl) == 0 && conn_->tls.rbuf.rleft() == 0)) {
+  if (!conn_ || !conn_->tls.ssl || !conn_->tls.initial_handshake_done ||
+      (SSL_pending(conn_->tls.ssl) == 0 && conn_->tls.rbuf.rleft() == 0 &&
+       conn_->tls.earlybuf.rleft() == 0)) {
     return;
   }
 

src/shrpx_tls.cc

@@ -510,6 +510,13 @@ int ticket_key_cb(SSL *ssl, unsigned char *key_name, unsigned char *iv,
 
 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
@@ -527,6 +534,105 @@ void info_callback(const SSL *ssl, int where, int ret) {
 }
 } // namespace
 
+#if OPENSSL_1_1_1_API
+constexpr auto MEMCACHED_ANTI_REPLY_KEY_PREFIX =
+    StringRef::from_lit("nghttpx:anti-reply:");
+
+namespace {
+int early_cb(SSL *ssl, int *al, void *arg) {
+  auto conn = static_cast<Connection *>(SSL_get_app_data(ssl));
+  if (conn->tls.early_cb_called) {
+    return 1;
+  }
+
+  conn->tls.early_cb_called = true;
+
+  const unsigned char *ext;
+  size_t extlen;
+
+  if (!SSL_client_hello_get0_ext(conn->tls.ssl, TLSEXT_TYPE_early_data, &ext,
+                                 &extlen)) {
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "early_data extension does not exist";
+    }
+    return 1;
+  }
+
+  if (!SSL_client_hello_get0_ext(conn->tls.ssl, TLSEXT_TYPE_psk, &ext,
+                                 &extlen)) {
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "pre_shared_key extension does not exist";
+    }
+    return 1;
+  }
+
+  std::array<uint8_t, 32> md;
+  unsigned int mdlen;
+  if (EVP_DigestFinal_ex(conn->tls.ch_md_ctx, md.data(), &mdlen) == 0) {
+    LOG(ERROR) << "EVP_DigestFinal_ex failed";
+    return 0;
+  }
+  assert(md.size() == mdlen);
+
+  auto handler = static_cast<ClientHandler *>(conn->data);
+  auto worker = handler->get_worker();
+  auto dispatcher = worker->get_anti_replay_memcached_dispatcher();
+  auto &balloc = handler->get_block_allocator();
+
+  auto &tlsconf = get_config()->tls;
+
+  conn->tls.ch_hex_md =
+      util::format_hex(balloc, StringRef{std::begin(md), std::end(md)});
+
+  if (tlsconf.anti_replay.memcached.host.empty()) {
+    return 1;
+  }
+
+  auto req = make_unique<MemcachedRequest>();
+  req->op = MEMCACHED_OP_ADD;
+  req->key = MEMCACHED_ANTI_REPLY_KEY_PREFIX.str();
+  req->key += conn->tls.ch_hex_md;
+
+  // TODO No value at the moment
+
+  // Set the same timeout value for session with the hope that
+  // OpenSSL library invalidates the outdated ticket.
+  req->expiry = tlsconf.session_timeout.count();
+  req->cb = [conn](MemcachedRequest *req, MemcachedResult res) {
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "Memcached: ClientHello anti-replay registration done.  key="
+                << req->key << ", status_code=" << 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.anti_replay_req = nullptr;
+
+    if (res.status_code != 0) {
+      // If we cannot add key/value, just postpone processing 0-RTT
+      // early data until handshake finishes.  Note that memcached
+      // atomically adds key/value.
+      conn->tls.postpone_early_data = true;
+    }
+
+    conn->tls.handshake_state = TLS_CONN_NORMAL;
+  };
+
+  conn->tls.handshake_state = TLS_CONN_WAIT_FOR_ANTI_REPLAY;
+  conn->tls.anti_replay_req = req.get();
+
+  dispatcher->add_request(std::move(req));
+
+  return -1;
+}
+} // namespace
+#endif // OPENSSL_1_1_1_API
+
 #if OPENSSL_VERSION_NUMBER >= 0x10002000L
 namespace {
 int alpn_select_proto_cb(SSL *ssl, const unsigned char **out,
@@ -913,6 +1019,10 @@ SSL_CTX *create_ssl_context(const char *private_key_file, const char *cert_file,
 #endif // OPENSSL_IS_BORINGSSL
   SSL_CTX_set_info_callback(ssl_ctx, info_callback);
 
+#if OPENSSL_1_1_1_API
+  SSL_CTX_set_client_hello_cb(ssl_ctx, early_cb, nullptr);
+#endif // OPENSSL_1_1_1_API
+
 #ifdef OPENSSL_IS_BORINGSSL
   SSL_CTX_set_early_data_enabled(ssl_ctx, 1);
 #endif // OPENSSL_IS_BORINGSSL

src/shrpx_worker.cc

@@ -118,6 +118,7 @@ bool match_shared_downstream_addr(
 
 Worker::Worker(struct ev_loop *loop, SSL_CTX *sv_ssl_ctx, SSL_CTX *cl_ssl_ctx,
                SSL_CTX *tls_session_cache_memcached_ssl_ctx,
+               SSL_CTX *tls_anti_replay_memcached_ssl_ctx,
                tls::CertLookupTree *cert_tree,
                const std::shared_ptr<TicketKeys> &ticket_keys,
                ConnectionHandler *conn_handler,
@@ -153,6 +154,15 @@ Worker::Worker(struct ev_loop *loop, SSL_CTX *sv_ssl_ctx, SSL_CTX *cl_ssl_ctx,
         StringRef{session_cacheconf.memcached.host}, &mcpool_, randgen_);
   }
 
+  auto &anti_replayconf = get_config()->tls.anti_replay;
+
+  if (!anti_replayconf.memcached.host.empty()) {
+    anti_replay_memcached_dispatcher_ = make_unique<MemcachedDispatcher>(
+        &anti_replayconf.memcached.addr, loop,
+        tls_anti_replay_memcached_ssl_ctx, anti_replayconf.memcached.host,
+        &mcpool_, randgen_);
+  }
+
   replace_downstream_config(std::move(downstreamconf));
 }
 
@@ -474,6 +484,10 @@ MemcachedDispatcher *Worker::get_session_cache_memcached_dispatcher() {
   return session_cache_memcached_dispatcher_.get();
 }
 
+MemcachedDispatcher *Worker::get_anti_replay_memcached_dispatcher() const {
+  return anti_replay_memcached_dispatcher_.get();
+}
+
 std::mt19937 &Worker::get_randgen() { return randgen_; }
 
 #ifdef HAVE_MRUBY

src/shrpx_worker.h

@@ -221,6 +221,7 @@ class Worker {
 public:
   Worker(struct ev_loop *loop, SSL_CTX *sv_ssl_ctx, SSL_CTX *cl_ssl_ctx,
          SSL_CTX *tls_session_cache_memcached_ssl_ctx,
+         SSL_CTX *tls_anti_replay_memcached_ssl_ctx,
          tls::CertLookupTree *cert_tree,
          const std::shared_ptr<TicketKeys> &ticket_keys,
          ConnectionHandler *conn_handler,
@@ -250,6 +251,7 @@ public:
   void schedule_clear_mcpool();
 
   MemcachedDispatcher *get_session_cache_memcached_dispatcher();
+  MemcachedDispatcher *get_anti_replay_memcached_dispatcher() const;
 
   std::mt19937 &get_randgen();
 
@@ -289,6 +291,7 @@ private:
 
   std::shared_ptr<DownstreamConfig> downstreamconf_;
   std::unique_ptr<MemcachedDispatcher> session_cache_memcached_dispatcher_;
+  std::unique_ptr<MemcachedDispatcher> anti_replay_memcached_dispatcher_;
 #ifdef HAVE_MRUBY
   std::unique_ptr<mruby::MRubyContext> mruby_ctx_;
 #endif // HAVE_MRUBY