Adding upstream version 14.2.21.upstream/14.2.21upstream

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

15 files changed, 2268 insertions, 0 deletions

diff --git a/src/crimson/net/Config.h b/src/crimson/net/Config.h
new file mode 100644
index 00000000..90929bde
--- /dev/null
+++ b/src/crimson/net/Config.h
@@ -0,0 +1,26 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+// XXX: a poor man's md_config_t
+#pragma once
+
+#include "include/msgr.h"
+#include <chrono>
+
+namespace ceph::net {
+
+using namespace std::literals::chrono_literals;
+
+constexpr struct simple_md_config_t {
+  uint32_t host_type = CEPH_ENTITY_TYPE_OSD;
+  bool cephx_require_signatures = false;
+  bool cephx_cluster_require_signatures = false;
+  bool cephx_service_require_signatures = false;
+  bool ms_die_on_old_message = true;
+  bool ms_die_on_skipped_message = true;
+  std::chrono::milliseconds ms_initial_backoff = 200ms;
+  std::chrono::milliseconds ms_max_backoff = 15000ms;
+  std::chrono::milliseconds threadpool_empty_queue_max_wait = 100ms;
+  size_t osd_client_message_size_cap = 500ULL << 20;
+} conf;
+}
diff --git a/src/crimson/net/Connection.h b/src/crimson/net/Connection.h
new file mode 100644
index 00000000..b1b72c74
--- /dev/null
+++ b/src/crimson/net/Connection.h
@@ -0,0 +1,66 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#pragma once
+
+#include <queue>
+#include <seastar/core/future.hh>
+#include <seastar/core/shared_ptr.hh>
+
+#include "Fwd.h"
+
+namespace ceph::net {
+
+using seq_num_t = uint64_t;
+
+class Connection : public seastar::enable_shared_from_this<Connection> {
+ protected:
+  entity_addr_t peer_addr;
+  peer_type_t peer_type = -1;
+
+ public:
+  Connection() {}
+  virtual ~Connection() {}
+
+  virtual Messenger* get_messenger() const = 0;
+  const entity_addr_t& get_peer_addr() const { return peer_addr; }
+  virtual int get_peer_type() const = 0;
+
+  /// true if the handshake has completed and no errors have been encountered
+  virtual seastar::future<bool> is_connected() = 0;
+
+  /// send a message over a connection that has completed its handshake
+  virtual seastar::future<> send(MessageRef msg) = 0;
+
+  /// send a keepalive message over a connection that has completed its
+  /// handshake
+  virtual seastar::future<> keepalive() = 0;
+
+  /// close the connection and cancel any any pending futures from read/send
+  virtual seastar::future<> close() = 0;
+
+  /// which shard id the connection lives
+  virtual seastar::shard_id shard_id() const = 0;
+
+  virtual void print(ostream& out) const = 0;
+};
+
+inline ostream& operator<<(ostream& out, const Connection& conn) {
+  out << "[";
+  conn.print(out);
+  out << "]";
+  return out;
+}
+
+} // namespace ceph::net
diff --git a/src/crimson/net/Dispatcher.cc b/src/crimson/net/Dispatcher.cc
new file mode 100644
index 00000000..336ded38
--- /dev/null
+++ b/src/crimson/net/Dispatcher.cc
@@ -0,0 +1,11 @@
+#include "auth/Auth.h"
+#include "Dispatcher.h"
+
+namespace ceph::net
+{
+seastar::future<std::unique_ptr<AuthAuthorizer>>
+Dispatcher::ms_get_authorizer(peer_type_t)
+{
+  return seastar::make_ready_future<std::unique_ptr<AuthAuthorizer>>(nullptr);
+}
+}
diff --git a/src/crimson/net/Dispatcher.h b/src/crimson/net/Dispatcher.h
new file mode 100644
index 00000000..cbde1549
--- /dev/null
+++ b/src/crimson/net/Dispatcher.h
@@ -0,0 +1,65 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#pragma once
+
+#include <seastar/core/future.hh>
+#include <seastar/core/sharded.hh>
+
+#include "Fwd.h"
+
+class AuthAuthorizer;
+
+namespace ceph::net {
+
+class Dispatcher {
+ public:
+  virtual ~Dispatcher() {}
+
+  virtual seastar::future<> ms_dispatch(ConnectionRef conn, MessageRef m) {
+    return seastar::make_ready_future<>();
+  }
+
+  virtual seastar::future<> ms_handle_accept(ConnectionRef conn) {
+    return seastar::make_ready_future<>();
+  }
+
+  virtual seastar::future<> ms_handle_connect(ConnectionRef conn) {
+    return seastar::make_ready_future<>();
+  }
+
+  virtual seastar::future<> ms_handle_reset(ConnectionRef conn) {
+    return seastar::make_ready_future<>();
+  }
+
+  virtual seastar::future<> ms_handle_remote_reset(ConnectionRef conn) {
+    return seastar::make_ready_future<>();
+  }
+
+  virtual seastar::future<msgr_tag_t, bufferlist>
+  ms_verify_authorizer(peer_type_t,
+		       auth_proto_t,
+		       bufferlist&) {
+    return seastar::make_ready_future<msgr_tag_t, bufferlist>(0, bufferlist{});
+  }
+  virtual seastar::future<std::unique_ptr<AuthAuthorizer>>
+  ms_get_authorizer(peer_type_t);
+
+  // get the local dispatcher shard if it is accessed by another core
+  virtual Dispatcher* get_local_shard() {
+    return this;
+  }
+};
+
+} // namespace ceph::net
diff --git a/src/crimson/net/Errors.cc b/src/crimson/net/Errors.cc
new file mode 100644
index 00000000..62d60ce1
--- /dev/null
+++ b/src/crimson/net/Errors.cc
@@ -0,0 +1,107 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#include "Errors.h"
+
+namespace ceph::net {
+
+const std::error_category& net_category()
+{
+  struct category : public std::error_category {
+    const char* name() const noexcept override {
+      return "ceph::net";
+    }
+
+    std::string message(int ev) const override {
+      switch (static_cast<error>(ev)) {
+        case error::success:
+          return "success";
+        case error::bad_connect_banner:
+          return "bad connect banner";
+        case error::bad_peer_address:
+          return "bad peer address";
+        case error::negotiation_failure:
+          return "negotiation failure";
+        case error::read_eof:
+          return "read eof";
+        case error::connection_aborted:
+          return "connection aborted";
+        case error::connection_refused:
+          return "connection refused";
+        case error::connection_reset:
+          return "connection reset";
+        default:
+          return "unknown";
+      }
+    }
+
+    // unfortunately, seastar throws connection errors with the system category,
+    // rather than the generic category that would match their counterparts
+    // in std::errc. we add our own errors for them, so we can match either
+    std::error_condition default_error_condition(int ev) const noexcept override {
+      switch (static_cast<error>(ev)) {
+        case error::connection_aborted:
+          return std::errc::connection_aborted;
+        case error::connection_refused:
+          return std::errc::connection_refused;
+        case error::connection_reset:
+          return std::errc::connection_reset;
+        default:
+          return std::error_condition(ev, *this);
+      }
+    }
+
+    bool equivalent(int code, const std::error_condition& cond) const noexcept override {
+      if (error_category::equivalent(code, cond)) {
+        return true;
+      }
+      switch (static_cast<error>(code)) {
+        case error::connection_aborted:
+          return cond == std::errc::connection_aborted
+              || cond == std::error_condition(ECONNABORTED, std::system_category());
+        case error::connection_refused:
+          return cond == std::errc::connection_refused
+              || cond == std::error_condition(ECONNREFUSED, std::system_category());
+        case error::connection_reset:
+          return cond == std::errc::connection_reset
+              || cond == std::error_condition(ECONNRESET, std::system_category());
+        default:
+          return false;
+      }
+    }
+
+    bool equivalent(const std::error_code& code, int cond) const noexcept override {
+      if (error_category::equivalent(code, cond)) {
+        return true;
+      }
+      switch (static_cast<error>(cond)) {
+        case error::connection_aborted:
+          return code == std::errc::connection_aborted
+              || code == std::error_code(ECONNABORTED, std::system_category());
+        case error::connection_refused:
+          return code == std::errc::connection_refused
+              || code == std::error_code(ECONNREFUSED, std::system_category());
+        case error::connection_reset:
+          return code == std::errc::connection_reset
+              || code == std::error_code(ECONNRESET, std::system_category());
+        default:
+          return false;
+      }
+    }
+  };
+  static category instance;
+  return instance;
+}
+
+} // namespace ceph::net
diff --git a/src/crimson/net/Errors.h b/src/crimson/net/Errors.h
new file mode 100644
index 00000000..d75082fd
--- /dev/null
+++ b/src/crimson/net/Errors.h
@@ -0,0 +1,54 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#pragma once
+
+#include <system_error>
+
+namespace ceph::net {
+
+/// net error codes
+enum class error {
+  success = 0,
+  bad_connect_banner,
+  bad_peer_address,
+  negotiation_failure,
+  read_eof,
+  connection_aborted,
+  connection_refused,
+  connection_reset,
+};
+
+/// net error category
+const std::error_category& net_category();
+
+inline std::error_code make_error_code(error e)
+{
+  return {static_cast<int>(e), net_category()};
+}
+
+inline std::error_condition make_error_condition(error e)
+{
+  return {static_cast<int>(e), net_category()};
+}
+
+} // namespace ceph::net
+
+namespace std {
+
+/// enables implicit conversion to std::error_condition
+template <>
+struct is_error_condition_enum<ceph::net::error> : public true_type {};
+
+} // namespace std
diff --git a/src/crimson/net/Fwd.h b/src/crimson/net/Fwd.h
new file mode 100644
index 00000000..8a0a1c96
--- /dev/null
+++ b/src/crimson/net/Fwd.h
@@ -0,0 +1,52 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#pragma once
+
+#include <seastar/core/shared_ptr.hh>
+#include <seastar/core/sharded.hh>
+
+#include "msg/msg_types.h"
+#include "msg/Message.h"
+
+using peer_type_t = int;
+using auth_proto_t = int;
+
+namespace ceph::net {
+
+using msgr_tag_t = uint8_t;
+
+class Connection;
+using ConnectionRef = seastar::shared_ptr<Connection>;
+// NOTE: ConnectionXRef should only be used in seastar world, because
+// lw_shared_ptr<> is not safe to be accessed by unpinned alien threads.
+using ConnectionXRef = seastar::lw_shared_ptr<seastar::foreign_ptr<ConnectionRef>>;
+
+class Dispatcher;
+
+class Messenger;
+
+template <typename T, typename... Args>
+seastar::future<T*> create_sharded(Args... args) {
+  auto sharded_obj = seastar::make_lw_shared<seastar::sharded<T>>();
+  return sharded_obj->start(args...).then([sharded_obj]() {
+      auto ret = &sharded_obj->local();
+      seastar::engine().at_exit([sharded_obj]() {
+          return sharded_obj->stop().finally([sharded_obj] {});
+        });
+      return ret;
+    });
+}
+
+} // namespace ceph::net
diff --git a/src/crimson/net/Messenger.cc b/src/crimson/net/Messenger.cc
new file mode 100644
index 00000000..7f8665ef
--- /dev/null
+++ b/src/crimson/net/Messenger.cc
@@ -0,0 +1,21 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "Messenger.h"
+#include "SocketMessenger.h"
+
+namespace ceph::net {
+
+seastar::future<Messenger*>
+Messenger::create(const entity_name_t& name,
+                  const std::string& lname,
+                  const uint64_t nonce,
+                  const int master_sid)
+{
+  return create_sharded<SocketMessenger>(name, lname, nonce, master_sid)
+    .then([](Messenger *msgr) {
+      return msgr;
+    });
+}
+
+} // namespace ceph::net
diff --git a/src/crimson/net/Messenger.h b/src/crimson/net/Messenger.h
new file mode 100644
index 00000000..9d766cb0
--- /dev/null
+++ b/src/crimson/net/Messenger.h
@@ -0,0 +1,117 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#pragma once
+
+#include <seastar/core/future.hh>
+
+#include "Fwd.h"
+#include "crimson/thread/Throttle.h"
+#include "msg/Policy.h"
+
+class AuthAuthorizer;
+
+namespace ceph::net {
+
+using Throttle = ceph::thread::Throttle;
+using SocketPolicy = ceph::net::Policy<Throttle>;
+
+class Messenger {
+  entity_name_t my_name;
+  entity_addrvec_t my_addrs;
+  uint32_t global_seq = 0;
+  uint32_t crc_flags = 0;
+
+ public:
+  Messenger(const entity_name_t& name)
+    : my_name(name)
+  {}
+  virtual ~Messenger() {}
+
+  const entity_name_t& get_myname() const { return my_name; }
+  const entity_addrvec_t& get_myaddrs() const { return my_addrs; }
+  entity_addr_t get_myaddr() const { return my_addrs.front(); }
+  virtual seastar::future<> set_myaddrs(const entity_addrvec_t& addrs) {
+    my_addrs = addrs;
+    return seastar::now();
+  }
+
+  /// bind to the given address
+  virtual seastar::future<> bind(const entity_addrvec_t& addr) = 0;
+
+  /// try to bind to the first unused port of given address
+  virtual seastar::future<> try_bind(const entity_addrvec_t& addr,
+                                     uint32_t min_port, uint32_t max_port) = 0;
+
+  /// start the messenger
+  virtual seastar::future<> start(Dispatcher *dispatcher) = 0;
+
+  /// either return an existing connection to the peer,
+  /// or a new pending connection
+  virtual seastar::future<ConnectionXRef>
+  connect(const entity_addr_t& peer_addr,
+          const entity_type_t& peer_type) = 0;
+
+  // wait for messenger shutdown
+  virtual seastar::future<> wait() = 0;
+
+  /// stop listenening and wait for all connections to close. safe to destruct
+  /// after this future becomes available
+  virtual seastar::future<> shutdown() = 0;
+
+  uint32_t get_global_seq(uint32_t old=0) {
+    if (old > global_seq) {
+      global_seq = old;
+    }
+    return ++global_seq;
+  }
+
+  uint32_t get_crc_flags() const {
+    return crc_flags;
+  }
+  void set_crc_data() {
+    crc_flags |= MSG_CRC_DATA;
+  }
+  void set_crc_header() {
+    crc_flags |= MSG_CRC_HEADER;
+  }
+
+  // get the local messenger shard if it is accessed by another core
+  virtual Messenger* get_local_shard() {
+    return this;
+  }
+
+  virtual void print(ostream& out) const = 0;
+
+  virtual void set_default_policy(const SocketPolicy& p) = 0;
+
+  virtual void set_policy(entity_type_t peer_type, const SocketPolicy& p) = 0;
+
+  virtual void set_policy_throttler(entity_type_t peer_type, Throttle* throttle) = 0;
+
+  static seastar::future<Messenger*>
+  create(const entity_name_t& name,
+         const std::string& lname,
+         const uint64_t nonce,
+         const int master_sid=-1);
+};
+
+inline ostream& operator<<(ostream& out, const Messenger& msgr) {
+  out << "[";
+  msgr.print(out);
+  out << "]";
+  return out;
+}
+
+} // namespace ceph::net
diff --git a/src/crimson/net/Socket.cc b/src/crimson/net/Socket.cc
new file mode 100644
index 00000000..a22e9b2e
--- /dev/null
+++ b/src/crimson/net/Socket.cc
@@ -0,0 +1,81 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "Socket.h"
+
+#include "Errors.h"
+
+namespace ceph::net {
+
+namespace {
+
+// an input_stream consumer that reads buffer segments into a bufferlist up to
+// the given number of remaining bytes
+struct bufferlist_consumer {
+  bufferlist& bl;
+  size_t& remaining;
+
+  bufferlist_consumer(bufferlist& bl, size_t& remaining)
+    : bl(bl), remaining(remaining) {}
+
+  using tmp_buf = seastar::temporary_buffer<char>;
+  using consumption_result_type = typename seastar::input_stream<char>::consumption_result_type;
+
+  // consume some or all of a buffer segment
+  seastar::future<consumption_result_type> operator()(tmp_buf&& data) {
+    if (remaining >= data.size()) {
+      // consume the whole buffer
+      remaining -= data.size();
+      bl.append(buffer::create_foreign(std::move(data)));
+      if (remaining > 0) {
+        // return none to request more segments
+        return seastar::make_ready_future<consumption_result_type>(
+            seastar::continue_consuming{});
+      } else {
+        // return an empty buffer to singal that we're done
+        return seastar::make_ready_future<consumption_result_type>(
+            consumption_result_type::stop_consuming_type({}));
+      }
+    }
+    if (remaining > 0) {
+      // consume the front
+      bl.append(buffer::create_foreign(data.share(0, remaining)));
+      data.trim_front(remaining);
+      remaining = 0;
+    }
+    // give the rest back to signal that we're done
+    return seastar::make_ready_future<consumption_result_type>(
+        consumption_result_type::stop_consuming_type{std::move(data)});
+  };
+};
+
+} // anonymous namespace
+
+seastar::future<bufferlist> Socket::read(size_t bytes)
+{
+  if (bytes == 0) {
+    return seastar::make_ready_future<bufferlist>();
+  }
+  r.buffer.clear();
+  r.remaining = bytes;
+  return in.consume(bufferlist_consumer{r.buffer, r.remaining})
+    .then([this] {
+      if (r.remaining) { // throw on short reads
+        throw std::system_error(make_error_code(error::read_eof));
+      }
+      return seastar::make_ready_future<bufferlist>(std::move(r.buffer));
+    });
+}
+
+seastar::future<seastar::temporary_buffer<char>>
+Socket::read_exactly(size_t bytes) {
+  return in.read_exactly(bytes)
+    .then([this](auto buf) {
+      if (buf.empty()) {
+        throw std::system_error(make_error_code(error::read_eof));
+      }
+      return seastar::make_ready_future<tmp_buf>(std::move(buf));
+    });
+}
+
+} // namespace ceph::net
diff --git a/src/crimson/net/Socket.h b/src/crimson/net/Socket.h
new file mode 100644
index 00000000..c1a2ed59
--- /dev/null
+++ b/src/crimson/net/Socket.h
@@ -0,0 +1,59 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#pragma once
+
+#include <seastar/core/reactor.hh>
+#include <seastar/net/packet.hh>
+
+#include "include/buffer.h"
+
+namespace ceph::net {
+
+class Socket
+{
+  const seastar::shard_id sid;
+  seastar::connected_socket socket;
+  seastar::input_stream<char> in;
+  seastar::output_stream<char> out;
+
+  /// buffer state for read()
+  struct {
+    bufferlist buffer;
+    size_t remaining;
+  } r;
+
+ public:
+  explicit Socket(seastar::connected_socket&& _socket)
+    : sid{seastar::engine().cpu_id()},
+      socket(std::move(_socket)),
+      in(socket.input()),
+      out(socket.output()) {}
+  Socket(Socket&& o) = delete;
+
+  /// read the requested number of bytes into a bufferlist
+  seastar::future<bufferlist> read(size_t bytes);
+  using tmp_buf = seastar::temporary_buffer<char>;
+  using packet = seastar::net::packet;
+  seastar::future<tmp_buf> read_exactly(size_t bytes);
+
+  seastar::future<> write(packet&& buf) {
+    return out.write(std::move(buf));
+  }
+  seastar::future<> flush() {
+    return out.flush();
+  }
+  seastar::future<> write_flush(packet&& buf) {
+    return out.write(std::move(buf)).then([this] { return out.flush(); });
+  }
+
+  /// Socket can only be closed once.
+  seastar::future<> close() {
+    return seastar::smp::submit_to(sid, [this] {
+        return seastar::when_all(
+          in.close(), out.close()).discard_result();
+      });
+  }
+};
+
+} // namespace ceph::net
diff --git a/src/crimson/net/SocketConnection.cc b/src/crimson/net/SocketConnection.cc
new file mode 100644
index 00000000..2907c486
--- /dev/null
+++ b/src/crimson/net/SocketConnection.cc
@@ -0,0 +1,972 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#include "SocketConnection.h"
+
+#include <algorithm>
+#include <seastar/core/shared_future.hh>
+#include <seastar/core/sleep.hh>
+#include <seastar/net/packet.hh>
+
+#include "include/msgr.h"
+#include "include/random.h"
+#include "auth/Auth.h"
+#include "auth/AuthSessionHandler.h"
+
+#include "crimson/common/log.h"
+#include "Config.h"
+#include "Dispatcher.h"
+#include "Errors.h"
+#include "SocketMessenger.h"
+
+using namespace ceph::net;
+
+template <typename T>
+seastar::net::packet make_static_packet(const T& value) {
+    return { reinterpret_cast<const char*>(&value), sizeof(value) };
+}
+
+namespace {
+  seastar::logger& logger() {
+    return ceph::get_logger(ceph_subsys_ms);
+  }
+}
+
+SocketConnection::SocketConnection(SocketMessenger& messenger,
+                                   Dispatcher& dispatcher)
+  : messenger(messenger),
+    dispatcher(dispatcher),
+    send_ready(h.promise.get_future())
+{
+  ceph_assert(&messenger.container().local() == &messenger);
+}
+
+SocketConnection::~SocketConnection()
+{
+  ceph_assert(pending_dispatch.is_closed());
+}
+
+ceph::net::Messenger*
+SocketConnection::get_messenger() const {
+  return &messenger;
+}
+
+seastar::future<bool> SocketConnection::is_connected()
+{
+  return seastar::smp::submit_to(shard_id(), [this] {
+      return !send_ready.failed();
+    });
+}
+
+seastar::future<> SocketConnection::send(MessageRef msg)
+{
+  return seastar::smp::submit_to(shard_id(), [this, msg=std::move(msg)] {
+      if (state == state_t::closing)
+        return seastar::now();
+      return seastar::with_gate(pending_dispatch, [this, msg=std::move(msg)] {
+          return do_send(std::move(msg))
+            .handle_exception([this] (std::exception_ptr eptr) {
+              logger().warn("{} send fault: {}", *this, eptr);
+              close();
+            });
+        });
+    });
+}
+
+seastar::future<> SocketConnection::keepalive()
+{
+  return seastar::smp::submit_to(shard_id(), [this] {
+      if (state == state_t::closing)
+        return seastar::now();
+      return seastar::with_gate(pending_dispatch, [this] {
+          return do_keepalive()
+            .handle_exception([this] (std::exception_ptr eptr) {
+              logger().warn("{} keepalive fault: {}", *this, eptr);
+              close();
+            });
+        });
+    });
+}
+
+seastar::future<> SocketConnection::close()
+{
+  return seastar::smp::submit_to(shard_id(), [this] {
+      return do_close();
+    });
+}
+
+seastar::future<> SocketConnection::handle_tags()
+{
+  return seastar::keep_doing([this] {
+      // read the next tag
+      return socket->read_exactly(1)
+        .then([this] (auto buf) {
+          switch (buf[0]) {
+          case CEPH_MSGR_TAG_MSG:
+            return read_message();
+          case CEPH_MSGR_TAG_ACK:
+            return handle_ack();
+          case CEPH_MSGR_TAG_KEEPALIVE:
+            return seastar::now();
+          case CEPH_MSGR_TAG_KEEPALIVE2:
+            return handle_keepalive2();
+          case CEPH_MSGR_TAG_KEEPALIVE2_ACK:
+            return handle_keepalive2_ack();
+          case CEPH_MSGR_TAG_CLOSE:
+            logger().info("{} got tag close", *this);
+            throw std::system_error(make_error_code(error::connection_aborted));
+          default:
+            logger().error("{} got unknown msgr tag {}", *this, static_cast<int>(buf[0]));
+            throw std::system_error(make_error_code(error::read_eof));
+          }
+        });
+    });
+}
+
+seastar::future<> SocketConnection::handle_ack()
+{
+  return socket->read_exactly(sizeof(ceph_le64))
+    .then([this] (auto buf) {
+      auto seq = reinterpret_cast<const ceph_le64*>(buf.get());
+      discard_up_to(&sent, *seq);
+    });
+}
+
+void SocketConnection::discard_up_to(std::queue<MessageRef>* queue,
+                                     seq_num_t seq)
+{
+  while (!queue->empty() &&
+         queue->front()->get_seq() < seq) {
+    queue->pop();
+  }
+}
+
+void SocketConnection::requeue_sent()
+{
+  out_seq -= sent.size();
+  while (!sent.empty()) {
+    auto m = sent.front();
+    sent.pop();
+    out_q.push(std::move(m));
+  }
+}
+
+seastar::future<> SocketConnection::maybe_throttle()
+{
+  if (!policy.throttler_bytes) {
+    return seastar::now();
+  }
+  const auto to_read = (m.header.front_len +
+                        m.header.middle_len +
+                        m.header.data_len);
+  return policy.throttler_bytes->get(to_read);
+}
+
+seastar::future<> SocketConnection::read_message()
+{
+  return socket->read(sizeof(m.header))
+    .then([this] (bufferlist bl) {
+      // throttle the traffic, maybe
+      auto p = bl.cbegin();
+      ::decode(m.header, p);
+      return maybe_throttle();
+    }).then([this] {
+      // read front
+      return socket->read(m.header.front_len);
+    }).then([this] (bufferlist bl) {
+      m.front = std::move(bl);
+      // read middle
+      return socket->read(m.header.middle_len);
+    }).then([this] (bufferlist bl) {
+      m.middle = std::move(bl);
+      // read data
+      return socket->read(m.header.data_len);
+    }).then([this] (bufferlist bl) {
+      m.data = std::move(bl);
+      // read footer
+      return socket->read(sizeof(m.footer));
+    }).then([this] (bufferlist bl) {
+      auto p = bl.cbegin();
+      ::decode(m.footer, p);
+      auto msg = ::decode_message(nullptr, 0, m.header, m.footer,
+                                  m.front, m.middle, m.data, nullptr);
+      // TODO: set time stamps
+      msg->set_byte_throttler(policy.throttler_bytes);
+
+      if (!update_rx_seq(msg->get_seq())) {
+        // skip this message
+        return;
+      }
+
+      constexpr bool add_ref = false; // Message starts with 1 ref
+      // TODO: change MessageRef with foreign_ptr
+      auto msg_ref = MessageRef{msg, add_ref};
+      // start dispatch, ignoring exceptions from the application layer
+      seastar::with_gate(pending_dispatch, [this, msg = std::move(msg_ref)] {
+          return dispatcher.ms_dispatch(
+              seastar::static_pointer_cast<SocketConnection>(shared_from_this()),
+              std::move(msg))
+            .handle_exception([this] (std::exception_ptr eptr) {
+              logger().error("{} ms_dispatch caught exception: {}", *this, eptr);
+              ceph_assert(false);
+            });
+        });
+    });
+}
+
+bool SocketConnection::update_rx_seq(seq_num_t seq)
+{
+  if (seq <= in_seq) {
+    if (HAVE_FEATURE(features, RECONNECT_SEQ) &&
+        conf.ms_die_on_old_message) {
+      ceph_abort_msg("old msgs despite reconnect_seq feature");
+    }
+    return false;
+  } else if (seq > in_seq + 1) {
+    if (conf.ms_die_on_skipped_message) {
+      ceph_abort_msg("skipped incoming seq");
+    }
+    return false;
+  } else {
+    in_seq = seq;
+    return true;
+  }
+}
+
+seastar::future<> SocketConnection::write_message(MessageRef msg)
+{
+  msg->set_seq(++out_seq);
+  auto& header = msg->get_header();
+  header.src = messenger.get_myname();
+  msg->encode(features, messenger.get_crc_flags());
+  bufferlist bl;
+  bl.append(CEPH_MSGR_TAG_MSG);
+  bl.append((const char*)&header, sizeof(header));
+  bl.append(msg->get_payload());
+  bl.append(msg->get_middle());
+  bl.append(msg->get_data());
+  auto& footer = msg->get_footer();
+  if (HAVE_FEATURE(features, MSG_AUTH)) {
+    bl.append((const char*)&footer, sizeof(footer));
+  } else {
+    ceph_msg_footer_old old_footer;
+    if (messenger.get_crc_flags() & MSG_CRC_HEADER) {
+      old_footer.front_crc = footer.front_crc;
+      old_footer.middle_crc = footer.middle_crc;
+    } else {
+      old_footer.front_crc = old_footer.middle_crc = 0;
+    }
+    if (messenger.get_crc_flags() & MSG_CRC_DATA) {
+      old_footer.data_crc = footer.data_crc;
+    } else {
+      old_footer.data_crc = 0;
+    }
+    old_footer.flags = footer.flags;
+    bl.append((const char*)&old_footer, sizeof(old_footer));
+  }
+  // write as a seastar::net::packet
+  return socket->write_flush(std::move(bl));
+  // TODO: lossless policy
+  //  .then([this, msg = std::move(msg)] {
+  //    if (!policy.lossy) {
+  //      sent.push(std::move(msg));
+  //    }
+  //  });
+}
+
+seastar::future<> SocketConnection::do_send(MessageRef msg)
+{
+  // chain the message after the last message is sent
+  // TODO: retry send for lossless connection
+  seastar::shared_future<> f = send_ready.then(
+    [this, msg = std::move(msg)] {
+      if (state == state_t::closing)
+        return seastar::now();
+      return write_message(std::move(msg));
+    });
+
+  // chain any later messages after this one completes
+  send_ready = f.get_future();
+  // allow the caller to wait on the same future
+  return f.get_future();
+}
+
+seastar::future<> SocketConnection::do_keepalive()
+{
+  // TODO: retry keepalive for lossless connection
+  seastar::shared_future<> f = send_ready.then([this] {
+      if (state == state_t::closing)
+        return seastar::now();
+      k.req.stamp = ceph::coarse_real_clock::to_ceph_timespec(
+        ceph::coarse_real_clock::now());
+      return socket->write_flush(make_static_packet(k.req));
+    });
+  send_ready = f.get_future();
+  return f.get_future();
+}
+
+seastar::future<> SocketConnection::do_close()
+{
+  if (state == state_t::closing) {
+    // already closing
+    assert(close_ready.valid());
+    return close_ready.get_future();
+  }
+
+  // unregister_conn() drops a reference, so hold another until completion
+  auto cleanup = [conn_ref = shared_from_this(), this] {
+      logger().debug("{} closed!", *this);
+    };
+
+  if (state == state_t::accepting) {
+    messenger.unaccept_conn(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+  } else if (state >= state_t::connecting && state < state_t::closing) {
+    messenger.unregister_conn(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+  } else {
+    // cannot happen
+    ceph_assert(false);
+  }
+
+  // close_ready become valid only after state is state_t::closing
+  assert(!close_ready.valid());
+
+  if (socket) {
+    close_ready = socket->close()
+      .then([this] {
+        return pending_dispatch.close();
+      }).finally(std::move(cleanup));
+  } else {
+    ceph_assert(state == state_t::connecting);
+    close_ready = pending_dispatch.close().finally(std::move(cleanup));
+  }
+  logger().debug("{} trigger closing, was {}", *this, static_cast<int>(state));
+  state = state_t::closing;
+  return close_ready.get_future();
+}
+
+// handshake
+
+/// store the banner in a non-const string for buffer::create_static()
+static char banner[] = CEPH_BANNER;
+constexpr size_t banner_size = sizeof(CEPH_BANNER)-1;
+
+constexpr size_t client_header_size = banner_size + sizeof(ceph_entity_addr);
+constexpr size_t server_header_size = banner_size + 2 * sizeof(ceph_entity_addr);
+
+WRITE_RAW_ENCODER(ceph_msg_connect);
+WRITE_RAW_ENCODER(ceph_msg_connect_reply);
+
+std::ostream& operator<<(std::ostream& out, const ceph_msg_connect& c)
+{
+  return out << "connect{features=" << std::hex << c.features << std::dec
+      << " host_type=" << c.host_type
+      << " global_seq=" << c.global_seq
+      << " connect_seq=" << c.connect_seq
+      << " protocol_version=" << c.protocol_version
+      << " authorizer_protocol=" << c.authorizer_protocol
+      << " authorizer_len=" << c.authorizer_len
+      << " flags=" << std::hex << static_cast<uint16_t>(c.flags) << std::dec << '}';
+}
+
+std::ostream& operator<<(std::ostream& out, const ceph_msg_connect_reply& r)
+{
+  return out << "connect_reply{tag=" << static_cast<uint16_t>(r.tag)
+      << " features=" << std::hex << r.features << std::dec
+      << " global_seq=" << r.global_seq
+      << " connect_seq=" << r.connect_seq
+      << " protocol_version=" << r.protocol_version
+      << " authorizer_len=" << r.authorizer_len
+      << " flags=" << std::hex << static_cast<uint16_t>(r.flags) << std::dec << '}';
+}
+
+// check that the buffer starts with a valid banner without requiring it to
+// be contiguous in memory
+static void validate_banner(bufferlist::const_iterator& p)
+{
+  auto b = std::cbegin(banner);
+  auto end = b + banner_size;
+  while (b != end) {
+    const char *buf{nullptr};
+    auto remaining = std::distance(b, end);
+    auto len = p.get_ptr_and_advance(remaining, &buf);
+    if (!std::equal(buf, buf + len, b)) {
+      throw std::system_error(make_error_code(error::bad_connect_banner));
+    }
+    b += len;
+  }
+}
+
+// make sure that we agree with the peer about its address
+static void validate_peer_addr(const entity_addr_t& addr,
+                               const entity_addr_t& expected)
+{
+  if (addr == expected) {
+    return;
+  }
+  // ok if server bound anonymously, as long as port/nonce match
+  if (addr.is_blank_ip() &&
+      addr.get_port() == expected.get_port() &&
+      addr.get_nonce() == expected.get_nonce()) {
+    return;
+  } else {
+    throw std::system_error(make_error_code(error::bad_peer_address));
+  }
+}
+
+/// return a static bufferptr to the given object
+template <typename T>
+bufferptr create_static(T& obj)
+{
+  return buffer::create_static(sizeof(obj), reinterpret_cast<char*>(&obj));
+}
+
+bool SocketConnection::require_auth_feature() const
+{
+  if (h.connect.authorizer_protocol != CEPH_AUTH_CEPHX) {
+    return false;
+  }
+  if (conf.cephx_require_signatures) {
+    return true;
+  }
+  if (h.connect.host_type == CEPH_ENTITY_TYPE_OSD ||
+      h.connect.host_type == CEPH_ENTITY_TYPE_MDS) {
+    return conf.cephx_cluster_require_signatures;
+  } else {
+    return conf.cephx_service_require_signatures;
+  }
+}
+
+uint32_t SocketConnection::get_proto_version(entity_type_t peer_type, bool connect) const
+{
+  constexpr entity_type_t my_type = CEPH_ENTITY_TYPE_OSD;
+  // see also OSD.h, unlike other connection of simple/async messenger,
+  // crimson msgr is only used by osd
+  constexpr uint32_t CEPH_OSD_PROTOCOL = 10;
+  if (peer_type == my_type) {
+    // internal
+    return CEPH_OSD_PROTOCOL;
+  } else {
+    // public
+    switch (connect ? peer_type : my_type) {
+      case CEPH_ENTITY_TYPE_OSD: return CEPH_OSDC_PROTOCOL;
+      case CEPH_ENTITY_TYPE_MDS: return CEPH_MDSC_PROTOCOL;
+      case CEPH_ENTITY_TYPE_MON: return CEPH_MONC_PROTOCOL;
+      default: return 0;
+    }
+  }
+}
+
+seastar::future<seastar::stop_iteration>
+SocketConnection::repeat_handle_connect()
+{
+  return socket->read(sizeof(h.connect))
+    .then([this](bufferlist bl) {
+      auto p = bl.cbegin();
+      ::decode(h.connect, p);
+      peer_type = h.connect.host_type;
+      return socket->read(h.connect.authorizer_len);
+    }).then([this] (bufferlist authorizer) {
+      if (h.connect.protocol_version != get_proto_version(h.connect.host_type, false)) {
+      	return seastar::make_ready_future<msgr_tag_t, bufferlist>(
+            CEPH_MSGR_TAG_BADPROTOVER, bufferlist{});
+      }
+      if (require_auth_feature()) {
+      	policy.features_required |= CEPH_FEATURE_MSG_AUTH;
+      }
+      if (auto feat_missing = policy.features_required & ~(uint64_t)h.connect.features;
+      	  feat_missing != 0) {
+        return seastar::make_ready_future<msgr_tag_t, bufferlist>(
+            CEPH_MSGR_TAG_FEATURES, bufferlist{});
+      }
+      return dispatcher.ms_verify_authorizer(peer_type,
+                                             h.connect.authorizer_protocol,
+                                             authorizer);
+    }).then([this] (ceph::net::msgr_tag_t tag, bufferlist&& authorizer_reply) {
+      memset(&h.reply, 0, sizeof(h.reply));
+      if (tag) {
+	return send_connect_reply(tag, std::move(authorizer_reply));
+      }
+      if (auto existing = messenger.lookup_conn(peer_addr); existing) {
+	return handle_connect_with_existing(existing, std::move(authorizer_reply));
+      } else if (h.connect.connect_seq > 0) {
+	return send_connect_reply(CEPH_MSGR_TAG_RESETSESSION,
+				  std::move(authorizer_reply));
+      }
+      h.connect_seq = h.connect.connect_seq + 1;
+      h.peer_global_seq = h.connect.global_seq;
+      set_features((uint64_t)policy.features_supported & (uint64_t)h.connect.features);
+      // TODO: cct
+      return send_connect_reply_ready(CEPH_MSGR_TAG_READY, std::move(authorizer_reply));
+    });
+}
+
+seastar::future<seastar::stop_iteration>
+SocketConnection::send_connect_reply(msgr_tag_t tag,
+                                     bufferlist&& authorizer_reply)
+{
+  h.reply.tag = tag;
+  h.reply.features = static_cast<uint64_t>((h.connect.features &
+					    policy.features_supported) |
+					   policy.features_required);
+  h.reply.authorizer_len = authorizer_reply.length();
+  return socket->write(make_static_packet(h.reply))
+    .then([this, reply=std::move(authorizer_reply)]() mutable {
+      return socket->write_flush(std::move(reply));
+    }).then([] {
+      return stop_t::no;
+    });
+}
+
+seastar::future<seastar::stop_iteration>
+SocketConnection::send_connect_reply_ready(msgr_tag_t tag,
+                                           bufferlist&& authorizer_reply)
+{
+  h.global_seq = messenger.get_global_seq();
+  h.reply.tag = tag;
+  h.reply.features = policy.features_supported;
+  h.reply.global_seq = h.global_seq;
+  h.reply.connect_seq = h.connect_seq;
+  h.reply.flags = 0;
+  if (policy.lossy) {
+    h.reply.flags = h.reply.flags | CEPH_MSG_CONNECT_LOSSY;
+  }
+  h.reply.authorizer_len = authorizer_reply.length();
+  return socket->write(make_static_packet(h.reply))
+    .then([this, reply=std::move(authorizer_reply)]() mutable {
+      if (reply.length()) {
+        return socket->write(std::move(reply));
+      } else {
+        return seastar::now();
+      }
+    }).then([this] {
+      if (h.reply.tag == CEPH_MSGR_TAG_SEQ) {
+        return socket->write_flush(make_static_packet(in_seq))
+          .then([this] {
+            return socket->read_exactly(sizeof(seq_num_t));
+          }).then([this] (auto buf) {
+            auto acked_seq = reinterpret_cast<const seq_num_t*>(buf.get());
+            discard_up_to(&out_q, *acked_seq);
+          });
+      } else {
+        return socket->flush();
+      }
+    }).then([this] {
+      return stop_t::yes;
+    });
+}
+
+seastar::future<>
+SocketConnection::handle_keepalive2()
+{
+  return socket->read_exactly(sizeof(ceph_timespec))
+    .then([this] (auto buf) {
+      k.ack.stamp = *reinterpret_cast<const ceph_timespec*>(buf.get());
+      seastar::shared_future<> f = send_ready.then([this] {
+          logger().debug("{} keepalive2 {}", *this, k.ack.stamp.tv_sec);
+          return socket->write_flush(make_static_packet(k.ack));
+        });
+      send_ready = f.get_future();
+      return f.get_future();
+    });
+}
+
+seastar::future<>
+SocketConnection::handle_keepalive2_ack()
+{
+  return socket->read_exactly(sizeof(ceph_timespec))
+    .then([this] (auto buf) {
+      auto t = reinterpret_cast<const ceph_timespec*>(buf.get());
+      k.ack_stamp = *t;
+      logger().debug("{} keepalive2 ack {}", *this, t->tv_sec);
+    });
+}
+
+seastar::future<seastar::stop_iteration>
+SocketConnection::handle_connect_with_existing(SocketConnectionRef existing, bufferlist&& authorizer_reply)
+{
+  if (h.connect.global_seq < existing->peer_global_seq()) {
+    h.reply.global_seq = existing->peer_global_seq();
+    return send_connect_reply(CEPH_MSGR_TAG_RETRY_GLOBAL);
+  } else if (existing->is_lossy()) {
+    return replace_existing(existing, std::move(authorizer_reply));
+  } else if (h.connect.connect_seq == 0 && existing->connect_seq() > 0) {
+    return replace_existing(existing, std::move(authorizer_reply), true);
+  } else if (h.connect.connect_seq < existing->connect_seq()) {
+    // old attempt, or we sent READY but they didn't get it.
+    h.reply.connect_seq = existing->connect_seq() + 1;
+    return send_connect_reply(CEPH_MSGR_TAG_RETRY_SESSION);
+  } else if (h.connect.connect_seq == existing->connect_seq()) {
+    // if the existing connection successfully opened, and/or
+    // subsequently went to standby, then the peer should bump
+    // their connect_seq and retry: this is not a connection race
+    // we need to resolve here.
+    if (existing->get_state() == state_t::open ||
+	existing->get_state() == state_t::standby) {
+      if (policy.resetcheck && existing->connect_seq() == 0) {
+	return replace_existing(existing, std::move(authorizer_reply));
+      } else {
+	h.reply.connect_seq = existing->connect_seq() + 1;
+	return send_connect_reply(CEPH_MSGR_TAG_RETRY_SESSION);
+      }
+    } else if (peer_addr < messenger.get_myaddr() ||
+	       existing->is_server_side()) {
+      // incoming wins
+      return replace_existing(existing, std::move(authorizer_reply));
+    } else {
+      return send_connect_reply(CEPH_MSGR_TAG_WAIT);
+    }
+  } else if (policy.resetcheck &&
+	     existing->connect_seq() == 0) {
+    return send_connect_reply(CEPH_MSGR_TAG_RESETSESSION);
+  } else {
+    return replace_existing(existing, std::move(authorizer_reply));
+  }
+}
+
+seastar::future<seastar::stop_iteration>
+SocketConnection::replace_existing(SocketConnectionRef existing,
+                                   bufferlist&& authorizer_reply,
+                                   bool is_reset_from_peer)
+{
+  msgr_tag_t reply_tag;
+  if (HAVE_FEATURE(h.connect.features, RECONNECT_SEQ) &&
+      !is_reset_from_peer) {
+    reply_tag = CEPH_MSGR_TAG_SEQ;
+  } else {
+    reply_tag = CEPH_MSGR_TAG_READY;
+  }
+  messenger.unregister_conn(existing);
+  if (!existing->is_lossy()) {
+    // reset the in_seq if this is a hard reset from peer,
+    // otherwise we respect our original connection's value
+    in_seq = is_reset_from_peer ? 0 : existing->rx_seq_num();
+    // steal outgoing queue and out_seq
+    existing->requeue_sent();
+    std::tie(out_seq, out_q) = existing->get_out_queue();
+  }
+  return send_connect_reply_ready(reply_tag, std::move(authorizer_reply));
+}
+
+seastar::future<seastar::stop_iteration>
+SocketConnection::handle_connect_reply(msgr_tag_t tag)
+{
+  switch (tag) {
+  case CEPH_MSGR_TAG_FEATURES:
+    logger().error("{} connect protocol feature mispatch", __func__);
+    throw std::system_error(make_error_code(error::negotiation_failure));
+  case CEPH_MSGR_TAG_BADPROTOVER:
+    logger().error("{} connect protocol version mispatch", __func__);
+    throw std::system_error(make_error_code(error::negotiation_failure));
+  case CEPH_MSGR_TAG_BADAUTHORIZER:
+    logger().error("{} got bad authorizer", __func__);
+    throw std::system_error(make_error_code(error::negotiation_failure));
+  case CEPH_MSGR_TAG_RESETSESSION:
+    reset_session();
+    return seastar::make_ready_future<stop_t>(stop_t::no);
+  case CEPH_MSGR_TAG_RETRY_GLOBAL:
+    h.global_seq = messenger.get_global_seq(h.reply.global_seq);
+    return seastar::make_ready_future<stop_t>(stop_t::no);
+  case CEPH_MSGR_TAG_RETRY_SESSION:
+    ceph_assert(h.reply.connect_seq > h.connect_seq);
+    h.connect_seq = h.reply.connect_seq;
+    return seastar::make_ready_future<stop_t>(stop_t::no);
+  case CEPH_MSGR_TAG_WAIT:
+    // TODO: state wait
+    throw std::system_error(make_error_code(error::negotiation_failure));
+  case CEPH_MSGR_TAG_SEQ:
+  case CEPH_MSGR_TAG_READY:
+    if (auto missing = (policy.features_required & ~(uint64_t)h.reply.features);
+        missing) {
+      logger().error("{} missing required features", __func__);
+      throw std::system_error(make_error_code(error::negotiation_failure));
+    }
+    return seastar::futurize_apply([this, tag] {
+        if (tag == CEPH_MSGR_TAG_SEQ) {
+          return socket->read_exactly(sizeof(seq_num_t))
+            .then([this] (auto buf) {
+              auto acked_seq = reinterpret_cast<const seq_num_t*>(buf.get());
+              discard_up_to(&out_q, *acked_seq);
+              return socket->write_flush(make_static_packet(in_seq));
+            });
+        }
+        // tag CEPH_MSGR_TAG_READY
+        return seastar::now();
+      }).then([this] {
+        // hooray!
+        h.peer_global_seq = h.reply.global_seq;
+        policy.lossy = h.reply.flags & CEPH_MSG_CONNECT_LOSSY;
+        h.connect_seq++;
+        h.backoff = 0ms;
+        set_features(h.reply.features & h.connect.features);
+        if (h.authorizer) {
+          session_security.reset(
+              get_auth_session_handler(nullptr,
+                                       h.authorizer->protocol,
+                                       h.authorizer->session_key,
+                                       features));
+        }
+        h.authorizer.reset();
+        return seastar::make_ready_future<stop_t>(stop_t::yes);
+      });
+    break;
+  default:
+    // unknown tag
+    logger().error("{} got unknown tag", __func__, int(tag));
+    throw std::system_error(make_error_code(error::negotiation_failure));
+  }
+}
+
+void SocketConnection::reset_session()
+{
+  decltype(out_q){}.swap(out_q);
+  decltype(sent){}.swap(sent);
+  in_seq = 0;
+  h.connect_seq = 0;
+  if (HAVE_FEATURE(features, MSG_AUTH)) {
+    // Set out_seq to a random value, so CRC won't be predictable.
+    // Constant to limit starting sequence number to 2^31.  Nothing special
+    // about it, just a big number.
+    constexpr uint64_t SEQ_MASK = 0x7fffffff;
+    out_seq = ceph::util::generate_random_number<uint64_t>(0, SEQ_MASK);
+  } else {
+    // previously, seq #'s always started at 0.
+    out_seq = 0;
+  }
+}
+
+seastar::future<seastar::stop_iteration>
+SocketConnection::repeat_connect()
+{
+  // encode ceph_msg_connect
+  memset(&h.connect, 0, sizeof(h.connect));
+  h.connect.features = policy.features_supported;
+  h.connect.host_type = messenger.get_myname().type();
+  h.connect.global_seq = h.global_seq;
+  h.connect.connect_seq = h.connect_seq;
+  h.connect.protocol_version = get_proto_version(peer_type, true);
+  // this is fyi, actually, server decides!
+  h.connect.flags = policy.lossy ? CEPH_MSG_CONNECT_LOSSY : 0;
+
+  return dispatcher.ms_get_authorizer(peer_type)
+    .then([this](auto&& auth) {
+      h.authorizer = std::move(auth);
+      bufferlist bl;
+      if (h.authorizer) {
+        h.connect.authorizer_protocol = h.authorizer->protocol;
+        h.connect.authorizer_len = h.authorizer->bl.length();
+        bl.append(create_static(h.connect));
+        bl.append(h.authorizer->bl);
+      } else {
+        h.connect.authorizer_protocol = 0;
+        h.connect.authorizer_len = 0;
+        bl.append(create_static(h.connect));
+      };
+      return socket->write_flush(std::move(bl));
+    }).then([this] {
+     // read the reply
+      return socket->read(sizeof(h.reply));
+    }).then([this] (bufferlist bl) {
+      auto p = bl.cbegin();
+      ::decode(h.reply, p);
+      ceph_assert(p.end());
+      return socket->read(h.reply.authorizer_len);
+    }).then([this] (bufferlist bl) {
+      if (h.authorizer) {
+        auto reply = bl.cbegin();
+        if (!h.authorizer->verify_reply(reply, nullptr)) {
+          logger().error("{} authorizer failed to verify reply", __func__);
+          throw std::system_error(make_error_code(error::negotiation_failure));
+        }
+      }
+      return handle_connect_reply(h.reply.tag);
+    });
+}
+
+void
+SocketConnection::start_connect(const entity_addr_t& _peer_addr,
+                                const entity_type_t& _peer_type)
+{
+  ceph_assert(state == state_t::none);
+  ceph_assert(!socket);
+  peer_addr = _peer_addr;
+  peer_type = _peer_type;
+  messenger.register_conn(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+  logger().debug("{} trigger connecting, was {}", *this, static_cast<int>(state));
+  state = state_t::connecting;
+  seastar::with_gate(pending_dispatch, [this] {
+      return seastar::connect(peer_addr.in4_addr())
+        .then([this](seastar::connected_socket fd) {
+          if (state == state_t::closing) {
+            fd.shutdown_input();
+            fd.shutdown_output();
+            throw std::system_error(make_error_code(error::connection_aborted));
+          }
+          socket = seastar::make_foreign(std::make_unique<Socket>(std::move(fd)));
+          // read server's handshake header
+          return socket->read(server_header_size);
+        }).then([this] (bufferlist headerbl) {
+          auto p = headerbl.cbegin();
+          validate_banner(p);
+          entity_addr_t saddr, caddr;
+          ::decode(saddr, p);
+          ::decode(caddr, p);
+          ceph_assert(p.end());
+          validate_peer_addr(saddr, peer_addr);
+
+          side = side_t::connector;
+          socket_port = caddr.get_port();
+          return messenger.learned_addr(caddr);
+        }).then([this] {
+          // encode/send client's handshake header
+          bufferlist bl;
+          bl.append(buffer::create_static(banner_size, banner));
+          ::encode(messenger.get_myaddr(), bl, 0);
+          h.global_seq = messenger.get_global_seq();
+          return socket->write_flush(std::move(bl));
+        }).then([=] {
+          return seastar::repeat([this] {
+            return repeat_connect();
+          });
+        }).then([this] {
+          // notify the dispatcher and allow them to reject the connection
+          return dispatcher.ms_handle_connect(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+        }).then([this] {
+          execute_open();
+        }).handle_exception([this] (std::exception_ptr eptr) {
+          // TODO: handle fault in the connecting state
+          logger().warn("{} connecting fault: {}", *this, eptr);
+          h.promise.set_value();
+          close();
+        });
+    });
+}
+
+void
+SocketConnection::start_accept(seastar::foreign_ptr<std::unique_ptr<Socket>>&& sock,
+                               const entity_addr_t& _peer_addr)
+{
+  ceph_assert(state == state_t::none);
+  ceph_assert(!socket);
+  peer_addr.u = _peer_addr.u;
+  peer_addr.set_port(0);
+  side = side_t::acceptor;
+  socket_port = _peer_addr.get_port();
+  socket = std::move(sock);
+  messenger.accept_conn(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+  logger().debug("{} trigger accepting, was {}", *this, static_cast<int>(state));
+  state = state_t::accepting;
+  seastar::with_gate(pending_dispatch, [this, _peer_addr] {
+      // encode/send server's handshake header
+      bufferlist bl;
+      bl.append(buffer::create_static(banner_size, banner));
+      ::encode(messenger.get_myaddr(), bl, 0);
+      ::encode(_peer_addr, bl, 0);
+      return socket->write_flush(std::move(bl))
+        .then([this] {
+          // read client's handshake header and connect request
+          return socket->read(client_header_size);
+        }).then([this] (bufferlist bl) {
+          auto p = bl.cbegin();
+          validate_banner(p);
+          entity_addr_t addr;
+          ::decode(addr, p);
+          ceph_assert(p.end());
+          peer_addr.set_type(addr.get_type());
+          peer_addr.set_port(addr.get_port());
+          peer_addr.set_nonce(addr.get_nonce());
+          return seastar::repeat([this] {
+            return repeat_handle_connect();
+          });
+        }).then([this] {
+          // notify the dispatcher and allow them to reject the connection
+          return dispatcher.ms_handle_accept(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+        }).then([this] {
+          messenger.register_conn(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+          messenger.unaccept_conn(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+          execute_open();
+        }).handle_exception([this] (std::exception_ptr eptr) {
+          // TODO: handle fault in the accepting state
+          logger().warn("{} accepting fault: {}", *this, eptr);
+          h.promise.set_value();
+          close();
+        });
+    });
+}
+
+void
+SocketConnection::execute_open()
+{
+  logger().debug("{} trigger open, was {}", *this, static_cast<int>(state));
+  state = state_t::open;
+  // satisfy the handshake's promise
+  h.promise.set_value();
+  seastar::with_gate(pending_dispatch, [this] {
+      // start background processing of tags
+      return handle_tags()
+        .handle_exception_type([this] (const std::system_error& e) {
+          logger().warn("{} open fault: {}", *this, e);
+          if (e.code() == error::connection_aborted ||
+              e.code() == error::connection_reset) {
+            return dispatcher.ms_handle_reset(seastar::static_pointer_cast<SocketConnection>(shared_from_this()))
+              .then([this] {
+                close();
+              });
+          } else if (e.code() == error::read_eof) {
+            return dispatcher.ms_handle_remote_reset(seastar::static_pointer_cast<SocketConnection>(shared_from_this()))
+              .then([this] {
+                close();
+              });
+          } else {
+            throw e;
+          }
+        }).handle_exception([this] (std::exception_ptr eptr) {
+          // TODO: handle fault in the open state
+          logger().warn("{} open fault: {}", *this, eptr);
+          close();
+        });
+    });
+}
+
+seastar::future<> SocketConnection::fault()
+{
+  if (policy.lossy) {
+    messenger.unregister_conn(seastar::static_pointer_cast<SocketConnection>(shared_from_this()));
+  }
+  if (h.backoff.count()) {
+    h.backoff += h.backoff;
+  } else {
+    h.backoff = conf.ms_initial_backoff;
+  }
+  if (h.backoff > conf.ms_max_backoff) {
+    h.backoff = conf.ms_max_backoff;
+  }
+  return seastar::sleep(h.backoff);
+}
+
+seastar::shard_id SocketConnection::shard_id() const {
+  return messenger.shard_id();
+}
+
+void SocketConnection::print(ostream& out) const {
+    messenger.print(out);
+    if (side == side_t::none) {
+      out << " >> " << peer_addr;
+    } else if (side == side_t::acceptor) {
+      out << " >> " << peer_addr
+          << "@" << socket_port;
+    } else { // side == side_t::connector
+      out << "@" << socket_port
+          << " >> " << peer_addr;
+    }
+}
diff --git a/src/crimson/net/SocketConnection.h b/src/crimson/net/SocketConnection.h
new file mode 100644
index 00000000..62cc77d5
--- /dev/null
+++ b/src/crimson/net/SocketConnection.h
@@ -0,0 +1,235 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#pragma once
+
+#include <seastar/core/gate.hh>
+#include <seastar/core/reactor.hh>
+#include <seastar/core/shared_future.hh>
+#include <seastar/core/sharded.hh>
+
+#include "msg/Policy.h"
+#include "Connection.h"
+#include "Socket.h"
+#include "crimson/thread/Throttle.h"
+
+class AuthAuthorizer;
+class AuthSessionHandler;
+
+namespace ceph::net {
+
+using stop_t = seastar::stop_iteration;
+
+class SocketMessenger;
+class SocketConnection;
+using SocketConnectionRef = seastar::shared_ptr<SocketConnection>;
+
+class SocketConnection : public Connection {
+  SocketMessenger& messenger;
+  seastar::foreign_ptr<std::unique_ptr<Socket>> socket;
+  Dispatcher& dispatcher;
+  seastar::gate pending_dispatch;
+
+  // if acceptor side, socket_port is different from peer_addr.get_port();
+  // if connector side, socket_port is different from my_addr.get_port().
+  enum class side_t {
+    none,
+    acceptor,
+    connector
+  };
+  side_t side = side_t::none;
+  uint16_t socket_port = 0;
+
+  enum class state_t {
+    none,
+    accepting,
+    connecting,
+    open,
+    standby,
+    wait,
+    closing
+  };
+  state_t state = state_t::none;
+
+  /// become valid only when state is state_t::closing
+  seastar::shared_future<> close_ready;
+
+  /// state for handshake
+  struct Handshake {
+    ceph_msg_connect connect;
+    ceph_msg_connect_reply reply;
+    std::unique_ptr<AuthAuthorizer> authorizer;
+    std::chrono::milliseconds backoff;
+    uint32_t connect_seq = 0;
+    uint32_t peer_global_seq = 0;
+    uint32_t global_seq;
+    seastar::promise<> promise;
+  } h;
+
+  /// server side of handshake negotiation
+  seastar::future<stop_t> repeat_handle_connect();
+  seastar::future<stop_t> handle_connect_with_existing(SocketConnectionRef existing,
+                                                        bufferlist&& authorizer_reply);
+  seastar::future<stop_t> replace_existing(SocketConnectionRef existing,
+                                            bufferlist&& authorizer_reply,
+                                            bool is_reset_from_peer = false);
+  seastar::future<stop_t> send_connect_reply(ceph::net::msgr_tag_t tag,
+                                              bufferlist&& authorizer_reply = {});
+  seastar::future<stop_t> send_connect_reply_ready(ceph::net::msgr_tag_t tag,
+                                                    bufferlist&& authorizer_reply);
+
+  seastar::future<> handle_keepalive2();
+  seastar::future<> handle_keepalive2_ack();
+
+  bool require_auth_feature() const;
+  uint32_t get_proto_version(entity_type_t peer_type, bool connec) const;
+  /// client side of handshake negotiation
+  seastar::future<stop_t> repeat_connect();
+  seastar::future<stop_t> handle_connect_reply(ceph::net::msgr_tag_t tag);
+  void reset_session();
+
+  /// state for an incoming message
+  struct MessageReader {
+    ceph_msg_header header;
+    ceph_msg_footer footer;
+    bufferlist front;
+    bufferlist middle;
+    bufferlist data;
+  } m;
+
+  seastar::future<> maybe_throttle();
+  seastar::future<> handle_tags();
+  seastar::future<> handle_ack();
+
+  /// becomes available when handshake completes, and when all previous messages
+  /// have been sent to the output stream. send() chains new messages as
+  /// continuations to this future to act as a queue
+  seastar::future<> send_ready;
+
+  /// encode/write a message
+  seastar::future<> write_message(MessageRef msg);
+
+  ceph::net::Policy<ceph::thread::Throttle> policy;
+  uint64_t features;
+  void set_features(uint64_t new_features) {
+    features = new_features;
+  }
+
+  /// the seq num of the last transmitted message
+  seq_num_t out_seq = 0;
+  /// the seq num of the last received message
+  seq_num_t in_seq = 0;
+  /// update the seq num of last received message
+  /// @returns true if the @c seq is valid, and @c in_seq is updated,
+  ///          false otherwise.
+  bool update_rx_seq(seq_num_t seq);
+
+  seastar::future<> read_message();
+
+  std::unique_ptr<AuthSessionHandler> session_security;
+
+  // messages to be resent after connection gets reset
+  std::queue<MessageRef> out_q;
+  // messages sent, but not yet acked by peer
+  std::queue<MessageRef> sent;
+  static void discard_up_to(std::queue<MessageRef>*, seq_num_t);
+
+  struct Keepalive {
+    struct {
+      const char tag = CEPH_MSGR_TAG_KEEPALIVE2;
+      ceph_timespec stamp;
+    } __attribute__((packed)) req;
+    struct {
+      const char tag = CEPH_MSGR_TAG_KEEPALIVE2_ACK;
+      ceph_timespec stamp;
+    } __attribute__((packed)) ack;
+    ceph_timespec ack_stamp;
+  } k;
+
+  seastar::future<> fault();
+
+  void execute_open();
+
+  seastar::future<> do_send(MessageRef msg);
+  seastar::future<> do_keepalive();
+  seastar::future<> do_close();
+
+ public:
+  SocketConnection(SocketMessenger& messenger,
+                   Dispatcher& dispatcher);
+  ~SocketConnection();
+
+  Messenger* get_messenger() const override;
+
+  int get_peer_type() const override {
+    return peer_type;
+  }
+
+  seastar::future<bool> is_connected() override;
+
+  seastar::future<> send(MessageRef msg) override;
+
+  seastar::future<> keepalive() override;
+
+  seastar::future<> close() override;
+
+  seastar::shard_id shard_id() const override;
+
+  void print(ostream& out) const override;
+
+ public:
+  /// start a handshake from the client's perspective,
+  /// only call when SocketConnection first construct
+  void start_connect(const entity_addr_t& peer_addr,
+                     const entity_type_t& peer_type);
+  /// start a handshake from the server's perspective,
+  /// only call when SocketConnection first construct
+  void start_accept(seastar::foreign_ptr<std::unique_ptr<Socket>>&& socket,
+                    const entity_addr_t& peer_addr);
+
+  /// the number of connections initiated in this session, increment when a
+  /// new connection is established
+  uint32_t connect_seq() const {
+    return h.connect_seq;
+  }
+
+  /// the client side should connect us with a gseq. it will be reset with
+  /// the one of exsting connection if it's greater.
+  uint32_t peer_global_seq() const {
+    return h.peer_global_seq;
+  }
+  seq_num_t rx_seq_num() const {
+    return in_seq;
+  }
+
+  /// current state of connection
+  state_t get_state() const {
+    return state;
+  }
+  bool is_server_side() const {
+    return policy.server;
+  }
+  bool is_lossy() const {
+    return policy.lossy;
+  }
+
+  /// move all messages in the sent list back into the queue
+  void requeue_sent();
+
+  std::tuple<seq_num_t, std::queue<MessageRef>> get_out_queue() {
+    return {out_seq, std::move(out_q)};
+  }
+};
+
+} // namespace ceph::net
diff --git a/src/crimson/net/SocketMessenger.cc b/src/crimson/net/SocketMessenger.cc
new file mode 100644
index 00000000..46a38ff7
--- /dev/null
+++ b/src/crimson/net/SocketMessenger.cc
@@ -0,0 +1,283 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#include "SocketMessenger.h"
+
+#include <tuple>
+#include <boost/functional/hash.hpp>
+
+#include "auth/Auth.h"
+#include "Errors.h"
+#include "Dispatcher.h"
+#include "Socket.h"
+
+using namespace ceph::net;
+
+namespace {
+  seastar::logger& logger() {
+    return ceph::get_logger(ceph_subsys_ms);
+  }
+}
+
+SocketMessenger::SocketMessenger(const entity_name_t& myname,
+                                 const std::string& logic_name,
+                                 uint32_t nonce,
+                                 int master_sid)
+  : Messenger{myname},
+    master_sid{master_sid},
+    sid{seastar::engine().cpu_id()},
+    logic_name{logic_name},
+    nonce{nonce}
+{}
+
+seastar::future<> SocketMessenger::set_myaddrs(const entity_addrvec_t& addrs)
+{
+  auto my_addrs = addrs;
+  for (auto& addr : my_addrs.v) {
+    addr.nonce = nonce;
+  }
+  return container().invoke_on_all([my_addrs](auto& msgr) {
+      return msgr.Messenger::set_myaddrs(my_addrs);
+    });
+}
+
+seastar::future<> SocketMessenger::bind(const entity_addrvec_t& addrs)
+{
+  ceph_assert(addrs.legacy_addr().get_family() == AF_INET);
+  auto my_addrs = addrs;
+  for (auto& addr : my_addrs.v) {
+    addr.nonce = nonce;
+  }
+  logger().info("listening on {}", my_addrs.legacy_addr().in4_addr());
+  return container().invoke_on_all([my_addrs](auto& msgr) {
+      msgr.do_bind(my_addrs);
+    });
+}
+
+seastar::future<>
+SocketMessenger::try_bind(const entity_addrvec_t& addrs,
+                          uint32_t min_port, uint32_t max_port)
+{
+  auto addr = addrs.legacy_or_front_addr();
+  if (addr.get_port() != 0) {
+    return bind(addrs);
+  }
+  ceph_assert(min_port <= max_port);
+  return seastar::do_with(uint32_t(min_port),
+    [this, max_port, addr] (auto& port) {
+      return seastar::repeat([this, max_port, addr, &port] {
+          auto to_bind = addr;
+          to_bind.set_port(port);
+          return bind(entity_addrvec_t{to_bind})
+            .then([this] {
+              logger().info("{}: try_bind: done", *this);
+              return stop_t::yes;
+            }).handle_exception_type([this, max_port, &port] (const std::system_error& e) {
+              logger().debug("{}: try_bind: {} already used", *this, port);
+              if (port == max_port) {
+                throw e;
+              }
+              ++port;
+              return stop_t::no;
+            });
+        });
+    });
+}
+
+seastar::future<> SocketMessenger::start(Dispatcher *disp) {
+  return container().invoke_on_all([disp](auto& msgr) {
+      return msgr.do_start(disp->get_local_shard());
+    });
+}
+
+seastar::future<ceph::net::ConnectionXRef>
+SocketMessenger::connect(const entity_addr_t& peer_addr, const entity_type_t& peer_type)
+{
+  auto shard = locate_shard(peer_addr);
+  return container().invoke_on(shard, [peer_addr, peer_type](auto& msgr) {
+      return msgr.do_connect(peer_addr, peer_type);
+    }).then([](seastar::foreign_ptr<ConnectionRef>&& conn) {
+      return seastar::make_lw_shared<seastar::foreign_ptr<ConnectionRef>>(std::move(conn));
+    });
+}
+
+seastar::future<> SocketMessenger::shutdown()
+{
+  return container().invoke_on_all([](auto& msgr) {
+      return msgr.do_shutdown();
+    }).finally([this] {
+      return container().invoke_on_all([](auto& msgr) {
+          msgr.shutdown_promise.set_value();
+        });
+    });
+}
+
+void SocketMessenger::do_bind(const entity_addrvec_t& addrs)
+{
+  Messenger::set_myaddrs(addrs);
+
+  // TODO: v2: listen on multiple addresses
+  seastar::socket_address address(addrs.legacy_addr().in4_addr());
+  seastar::listen_options lo;
+  lo.reuse_address = true;
+  listener = seastar::listen(address, lo);
+}
+
+seastar::future<> SocketMessenger::do_start(Dispatcher *disp)
+{
+  dispatcher = disp;
+
+  // start listening if bind() was called
+  if (listener) {
+    seastar::keep_doing([this] {
+        return listener->accept()
+          .then([this] (seastar::connected_socket socket,
+                        seastar::socket_address paddr) {
+            // allocate the connection
+            entity_addr_t peer_addr;
+            peer_addr.set_sockaddr(&paddr.as_posix_sockaddr());
+            auto shard = locate_shard(peer_addr);
+#warning fixme
+            // we currently do dangerous i/o from a Connection core, different from the Socket core.
+            auto sock = seastar::make_foreign(std::make_unique<Socket>(std::move(socket)));
+            // don't wait before accepting another
+            container().invoke_on(shard, [sock = std::move(sock), peer_addr, this](auto& msgr) mutable {
+                SocketConnectionRef conn = seastar::make_shared<SocketConnection>(msgr, *msgr.dispatcher);
+                conn->start_accept(std::move(sock), peer_addr);
+              });
+          });
+      }).handle_exception_type([this] (const std::system_error& e) {
+        // stop gracefully on connection_aborted
+        if (e.code() != error::connection_aborted) {
+          logger().error("{} unexpected error during accept: {}", *this, e);
+        }
+      });
+  }
+
+  return seastar::now();
+}
+
+seastar::foreign_ptr<ceph::net::ConnectionRef>
+SocketMessenger::do_connect(const entity_addr_t& peer_addr, const entity_type_t& peer_type)
+{
+  if (auto found = lookup_conn(peer_addr); found) {
+    return seastar::make_foreign(found->shared_from_this());
+  }
+  SocketConnectionRef conn = seastar::make_shared<SocketConnection>(*this, *dispatcher);
+  conn->start_connect(peer_addr, peer_type);
+  return seastar::make_foreign(conn->shared_from_this());
+}
+
+seastar::future<> SocketMessenger::do_shutdown()
+{
+  if (listener) {
+    listener->abort_accept();
+  }
+  // close all connections
+  return seastar::parallel_for_each(accepting_conns, [] (auto conn) {
+      return conn->close();
+    }).then([this] {
+      ceph_assert(accepting_conns.empty());
+      return seastar::parallel_for_each(connections, [] (auto conn) {
+          return conn.second->close();
+        });
+    }).finally([this] {
+      ceph_assert(connections.empty());
+    });
+}
+
+seastar::future<> SocketMessenger::learned_addr(const entity_addr_t &peer_addr_for_me)
+{
+  if (!get_myaddr().is_blank_ip()) {
+    // already learned or binded
+    return seastar::now();
+  }
+
+  // Only learn IP address if blank.
+  entity_addr_t addr = get_myaddr();
+  addr.u = peer_addr_for_me.u;
+  addr.set_type(peer_addr_for_me.get_type());
+  addr.set_port(get_myaddr().get_port());
+  return set_myaddrs(entity_addrvec_t{addr});
+}
+
+void SocketMessenger::set_default_policy(const SocketPolicy& p)
+{
+  policy_set.set_default(p);
+}
+
+void SocketMessenger::set_policy(entity_type_t peer_type,
+				 const SocketPolicy& p)
+{
+  policy_set.set(peer_type, p);
+}
+
+void SocketMessenger::set_policy_throttler(entity_type_t peer_type,
+					   Throttle* throttle)
+{
+  // only byte throttler is used in OSD
+  policy_set.set_throttlers(peer_type, throttle, nullptr);
+}
+
+seastar::shard_id SocketMessenger::locate_shard(const entity_addr_t& addr)
+{
+  ceph_assert(addr.get_family() == AF_INET);
+  if (master_sid >= 0) {
+    return master_sid;
+  }
+  std::size_t seed = 0;
+  boost::hash_combine(seed, addr.u.sin.sin_addr.s_addr);
+  //boost::hash_combine(seed, addr.u.sin.sin_port);
+  //boost::hash_combine(seed, addr.nonce);
+  return seed % seastar::smp::count;
+}
+
+ceph::net::SocketConnectionRef SocketMessenger::lookup_conn(const entity_addr_t& addr)
+{
+  if (auto found = connections.find(addr);
+      found != connections.end()) {
+    return found->second;
+  } else {
+    return nullptr;
+  }
+}
+
+void SocketMessenger::accept_conn(SocketConnectionRef conn)
+{
+  accepting_conns.insert(conn);
+}
+
+void SocketMessenger::unaccept_conn(SocketConnectionRef conn)
+{
+  accepting_conns.erase(conn);
+}
+
+void SocketMessenger::register_conn(SocketConnectionRef conn)
+{
+  if (master_sid >= 0) {
+    ceph_assert(static_cast<int>(sid) == master_sid);
+  }
+  auto [i, added] = connections.emplace(conn->get_peer_addr(), conn);
+  std::ignore = i;
+  ceph_assert(added);
+}
+
+void SocketMessenger::unregister_conn(SocketConnectionRef conn)
+{
+  ceph_assert(conn);
+  auto found = connections.find(conn->get_peer_addr());
+  ceph_assert(found != connections.end());
+  ceph_assert(found->second == conn);
+  connections.erase(found);
+}
diff --git a/src/crimson/net/SocketMessenger.h b/src/crimson/net/SocketMessenger.h
new file mode 100644
index 00000000..535dea3a
--- /dev/null
+++ b/src/crimson/net/SocketMessenger.h
@@ -0,0 +1,119 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 Red Hat, Inc
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#pragma once
+
+#include <map>
+#include <optional>
+#include <set>
+#include <seastar/core/gate.hh>
+#include <seastar/core/reactor.hh>
+#include <seastar/core/sharded.hh>
+
+#include "Messenger.h"
+#include "SocketConnection.h"
+
+namespace ceph::net {
+
+class SocketMessenger final : public Messenger, public seastar::peering_sharded_service<SocketMessenger> {
+  const int master_sid;
+  const seastar::shard_id sid;
+  seastar::promise<> shutdown_promise;
+
+  std::optional<seastar::server_socket> listener;
+  Dispatcher *dispatcher = nullptr;
+  std::map<entity_addr_t, SocketConnectionRef> connections;
+  std::set<SocketConnectionRef> accepting_conns;
+  ceph::net::PolicySet<Throttle> policy_set;
+  // Distinguish messengers with meaningful names for debugging
+  const std::string logic_name;
+  const uint32_t nonce;
+
+  seastar::future<> accept(seastar::connected_socket socket,
+                           seastar::socket_address paddr);
+
+  void do_bind(const entity_addrvec_t& addr);
+  seastar::future<> do_start(Dispatcher *disp);
+  seastar::foreign_ptr<ConnectionRef> do_connect(const entity_addr_t& peer_addr,
+                                                 const entity_type_t& peer_type);
+  seastar::future<> do_shutdown();
+  // conn sharding options:
+  // 0. Compatible (master_sid >= 0): place all connections to one master shard
+  // 1. Simplest (master_sid < 0): sharded by ip only
+  // 2. Balanced (not implemented): sharded by ip + port + nonce,
+  //        but, need to move SocketConnection between cores.
+  seastar::shard_id locate_shard(const entity_addr_t& addr);
+
+ public:
+  SocketMessenger(const entity_name_t& myname,
+                  const std::string& logic_name,
+                  uint32_t nonce,
+                  int master_sid);
+
+  seastar::future<> set_myaddrs(const entity_addrvec_t& addr) override;
+
+  // Messenger interfaces are assumed to be called from its own shard, but its
+  // behavior should be symmetric when called from any shard.
+  seastar::future<> bind(const entity_addrvec_t& addr) override;
+
+  seastar::future<> try_bind(const entity_addrvec_t& addr,
+                             uint32_t min_port, uint32_t max_port) override;
+
+  seastar::future<> start(Dispatcher *dispatcher) override;
+
+  seastar::future<ConnectionXRef> connect(const entity_addr_t& peer_addr,
+                                          const entity_type_t& peer_type) override;
+  // can only wait once
+  seastar::future<> wait() override {
+    return shutdown_promise.get_future();
+  }
+
+  seastar::future<> shutdown() override;
+
+  Messenger* get_local_shard() override {
+    return &container().local();
+  }
+
+  void print(ostream& out) const override {
+    out << get_myname()
+        << "(" << logic_name
+        << ") " << get_myaddr();
+  }
+
+  void set_default_policy(const SocketPolicy& p) override;
+
+  void set_policy(entity_type_t peer_type, const SocketPolicy& p) override;
+
+  void set_policy_throttler(entity_type_t peer_type, Throttle* throttle) override;
+
+ public:
+  seastar::future<> learned_addr(const entity_addr_t &peer_addr_for_me);
+
+  SocketConnectionRef lookup_conn(const entity_addr_t& addr);
+  void accept_conn(SocketConnectionRef);
+  void unaccept_conn(SocketConnectionRef);
+  void register_conn(SocketConnectionRef);
+  void unregister_conn(SocketConnectionRef);
+
+  // required by sharded<>
+  seastar::future<> stop() {
+    return seastar::make_ready_future<>();
+  }
+
+  seastar::shard_id shard_id() const {
+    return sid;
+  }
+};
+
+} // namespace ceph::net