Adding upstream version 14.2.21.upstream/14.2.21upstream

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

1 files changed, 972 insertions, 0 deletions

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;
+    }
+}