Adding upstream version 1.52.0.upstream/1.52.0upstream

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

1 files changed, 1602 insertions, 0 deletions

diff --git a/src/shrpx_http_downstream_connection.cc b/src/shrpx_http_downstream_connection.cc
new file mode 100644
index 0000000..96ce4b2
--- /dev/null
+++ b/src/shrpx_http_downstream_connection.cc
@@ -0,0 +1,1602 @@
+/*
+ * nghttp2 - HTTP/2 C Library
+ *
+ * Copyright (c) 2012 Tatsuhiro Tsujikawa
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "shrpx_http_downstream_connection.h"
+
+#include <openssl/rand.h>
+
+#include "shrpx_client_handler.h"
+#include "shrpx_upstream.h"
+#include "shrpx_downstream.h"
+#include "shrpx_config.h"
+#include "shrpx_error.h"
+#include "shrpx_http.h"
+#include "shrpx_log_config.h"
+#include "shrpx_connect_blocker.h"
+#include "shrpx_downstream_connection_pool.h"
+#include "shrpx_worker.h"
+#include "shrpx_http2_session.h"
+#include "shrpx_tls.h"
+#include "shrpx_log.h"
+#include "http2.h"
+#include "util.h"
+#include "ssl_compat.h"
+
+using namespace nghttp2;
+
+namespace shrpx {
+
+namespace {
+void timeoutcb(struct ev_loop *loop, ev_timer *w, int revents) {
+  auto conn = static_cast<Connection *>(w->data);
+  auto dconn = static_cast<HttpDownstreamConnection *>(conn->data);
+
+  if (w == &conn->rt && !conn->expired_rt()) {
+    return;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    DCLOG(INFO, dconn) << "Time out";
+  }
+
+  auto downstream = dconn->get_downstream();
+  auto upstream = downstream->get_upstream();
+  auto handler = upstream->get_client_handler();
+  auto &resp = downstream->response();
+
+  // Do this so that dconn is not pooled
+  resp.connection_close = true;
+
+  if (upstream->downstream_error(dconn, Downstream::EVENT_TIMEOUT) != 0) {
+    delete handler;
+  }
+}
+} // namespace
+
+namespace {
+void retry_downstream_connection(Downstream *downstream,
+                                 unsigned int status_code) {
+  auto upstream = downstream->get_upstream();
+  auto handler = upstream->get_client_handler();
+
+  assert(!downstream->get_request_header_sent());
+
+  downstream->add_retry();
+
+  if (downstream->no_more_retry()) {
+    delete handler;
+    return;
+  }
+
+  downstream->pop_downstream_connection();
+  auto buf = downstream->get_request_buf();
+  buf->reset();
+
+  int rv;
+
+  for (;;) {
+    auto ndconn = handler->get_downstream_connection(rv, downstream);
+    if (!ndconn) {
+      break;
+    }
+    if (downstream->attach_downstream_connection(std::move(ndconn)) != 0) {
+      continue;
+    }
+    if (downstream->push_request_headers() == 0) {
+      return;
+    }
+  }
+
+  downstream->set_request_state(DownstreamState::CONNECT_FAIL);
+
+  if (rv == SHRPX_ERR_TLS_REQUIRED) {
+    rv = upstream->on_downstream_abort_request_with_https_redirect(downstream);
+  } else {
+    rv = upstream->on_downstream_abort_request(downstream, status_code);
+  }
+
+  if (rv != 0) {
+    delete handler;
+  }
+}
+} // namespace
+
+namespace {
+void connect_timeoutcb(struct ev_loop *loop, ev_timer *w, int revents) {
+  auto conn = static_cast<Connection *>(w->data);
+  auto dconn = static_cast<HttpDownstreamConnection *>(conn->data);
+  auto addr = dconn->get_addr();
+  auto raddr = dconn->get_raddr();
+
+  DCLOG(WARN, dconn) << "Connect time out; addr="
+                     << util::to_numeric_addr(raddr);
+
+  downstream_failure(addr, raddr);
+
+  auto downstream = dconn->get_downstream();
+
+  retry_downstream_connection(downstream, 504);
+}
+} // namespace
+
+namespace {
+void backend_retry(Downstream *downstream) {
+  retry_downstream_connection(downstream, 502);
+}
+} // namespace
+
+namespace {
+void readcb(struct ev_loop *loop, ev_io *w, int revents) {
+  int rv;
+  auto conn = static_cast<Connection *>(w->data);
+  auto dconn = static_cast<HttpDownstreamConnection *>(conn->data);
+  auto downstream = dconn->get_downstream();
+  auto upstream = downstream->get_upstream();
+  auto handler = upstream->get_client_handler();
+
+  rv = upstream->downstream_read(dconn);
+  if (rv != 0) {
+    if (rv == SHRPX_ERR_RETRY) {
+      backend_retry(downstream);
+      return;
+    }
+
+    delete handler;
+  }
+}
+} // namespace
+
+namespace {
+void writecb(struct ev_loop *loop, ev_io *w, int revents) {
+  int rv;
+  auto conn = static_cast<Connection *>(w->data);
+  auto dconn = static_cast<HttpDownstreamConnection *>(conn->data);
+  auto downstream = dconn->get_downstream();
+  auto upstream = downstream->get_upstream();
+  auto handler = upstream->get_client_handler();
+
+  rv = upstream->downstream_write(dconn);
+  if (rv == SHRPX_ERR_RETRY) {
+    backend_retry(downstream);
+    return;
+  }
+
+  if (rv != 0) {
+    delete handler;
+  }
+}
+} // namespace
+
+namespace {
+void connectcb(struct ev_loop *loop, ev_io *w, int revents) {
+  auto conn = static_cast<Connection *>(w->data);
+  auto dconn = static_cast<HttpDownstreamConnection *>(conn->data);
+  auto downstream = dconn->get_downstream();
+  if (dconn->connected() != 0) {
+    backend_retry(downstream);
+    return;
+  }
+  writecb(loop, w, revents);
+}
+} // namespace
+
+HttpDownstreamConnection::HttpDownstreamConnection(
+    const std::shared_ptr<DownstreamAddrGroup> &group, DownstreamAddr *addr,
+    struct ev_loop *loop, Worker *worker)
+    : conn_(loop, -1, nullptr, worker->get_mcpool(),
+            group->shared_addr->timeout.write, group->shared_addr->timeout.read,
+            {}, {}, connectcb, readcb, connect_timeoutcb, this,
+            get_config()->tls.dyn_rec.warmup_threshold,
+            get_config()->tls.dyn_rec.idle_timeout, Proto::HTTP1),
+      on_read_(&HttpDownstreamConnection::noop),
+      on_write_(&HttpDownstreamConnection::noop),
+      signal_write_(&HttpDownstreamConnection::noop),
+      worker_(worker),
+      ssl_ctx_(worker->get_cl_ssl_ctx()),
+      group_(group),
+      addr_(addr),
+      raddr_(nullptr),
+      ioctrl_(&conn_.rlimit),
+      response_htp_{0},
+      first_write_done_(false),
+      reusable_(true),
+      request_header_written_(false) {}
+
+HttpDownstreamConnection::~HttpDownstreamConnection() {
+  if (LOG_ENABLED(INFO)) {
+    DCLOG(INFO, this) << "Deleted";
+  }
+
+  if (dns_query_) {
+    auto dns_tracker = worker_->get_dns_tracker();
+    dns_tracker->cancel(dns_query_.get());
+  }
+}
+
+int HttpDownstreamConnection::attach_downstream(Downstream *downstream) {
+  int rv;
+
+  if (LOG_ENABLED(INFO)) {
+    DCLOG(INFO, this) << "Attaching to DOWNSTREAM:" << downstream;
+  }
+
+  downstream_ = downstream;
+
+  rv = initiate_connection();
+  if (rv != 0) {
+    downstream_ = nullptr;
+    return rv;
+  }
+
+  return 0;
+}
+
+namespace {
+int htp_msg_begincb(llhttp_t *htp);
+int htp_hdr_keycb(llhttp_t *htp, const char *data, size_t len);
+int htp_hdr_valcb(llhttp_t *htp, const char *data, size_t len);
+int htp_hdrs_completecb(llhttp_t *htp);
+int htp_bodycb(llhttp_t *htp, const char *data, size_t len);
+int htp_msg_completecb(llhttp_t *htp);
+} // namespace
+
+namespace {
+constexpr llhttp_settings_t htp_hooks = {
+    htp_msg_begincb,     // llhttp_cb      on_message_begin;
+    nullptr,             // llhttp_data_cb on_url;
+    nullptr,             // llhttp_data_cb on_status;
+    nullptr,             // llhttp_data_cb on_method;
+    nullptr,             // llhttp_data_cb on_version;
+    htp_hdr_keycb,       // llhttp_data_cb on_header_field;
+    htp_hdr_valcb,       // llhttp_data_cb on_header_value;
+    nullptr,             // llhttp_data_cb on_chunk_extension_name;
+    nullptr,             // llhttp_data_cb on_chunk_extension_value;
+    htp_hdrs_completecb, // llhttp_cb      on_headers_complete;
+    htp_bodycb,          // llhttp_data_cb on_body;
+    htp_msg_completecb,  // llhttp_cb      on_message_complete;
+    nullptr,             // llhttp_cb      on_url_complete;
+    nullptr,             // llhttp_cb      on_status_complete;
+    nullptr,             // llhttp_cb      on_method_complete;
+    nullptr,             // llhttp_cb      on_version_complete;
+    nullptr,             // llhttp_cb      on_header_field_complete;
+    nullptr,             // llhttp_cb      on_header_value_complete;
+    nullptr,             // llhttp_cb      on_chunk_extension_name_complete;
+    nullptr,             // llhttp_cb      on_chunk_extension_value_complete;
+    nullptr,             // llhttp_cb      on_chunk_header;
+    nullptr,             // llhttp_cb      on_chunk_complete;
+    nullptr,             // llhttp_cb      on_reset;
+};
+} // namespace
+
+int HttpDownstreamConnection::initiate_connection() {
+  int rv;
+
+  auto worker_blocker = worker_->get_connect_blocker();
+  if (worker_blocker->blocked()) {
+    if (LOG_ENABLED(INFO)) {
+      DCLOG(INFO, this)
+          << "Worker wide backend connection was blocked temporarily";
+    }
+    return SHRPX_ERR_NETWORK;
+  }
+
+  auto &downstreamconf = *worker_->get_downstream_config();
+
+  if (conn_.fd == -1) {
+    auto check_dns_result = dns_query_.get() != nullptr;
+
+    if (check_dns_result) {
+      assert(addr_->dns);
+    }
+
+    auto &connect_blocker = addr_->connect_blocker;
+
+    if (connect_blocker->blocked()) {
+      if (LOG_ENABLED(INFO)) {
+        DCLOG(INFO, this) << "Backend server " << addr_->host << ":"
+                          << addr_->port << " was not available temporarily";
+      }
+
+      return SHRPX_ERR_NETWORK;
+    }
+
+    Address *raddr;
+
+    if (addr_->dns) {
+      if (!check_dns_result) {
+        auto dns_query = std::make_unique<DNSQuery>(
+            addr_->host,
+            [this](DNSResolverStatus status, const Address *result) {
+              int rv;
+
+              if (status == DNSResolverStatus::OK) {
+                *this->resolved_addr_ = *result;
+              }
+
+              rv = this->initiate_connection();
+              if (rv != 0) {
+                // This callback destroys |this|.
+                auto downstream = this->downstream_;
+                backend_retry(downstream);
+              }
+            });
+
+        auto dns_tracker = worker_->get_dns_tracker();
+
+        if (!resolved_addr_) {
+          resolved_addr_ = std::make_unique<Address>();
+        }
+        switch (dns_tracker->resolve(resolved_addr_.get(), dns_query.get())) {
+        case DNSResolverStatus::ERROR:
+          downstream_failure(addr_, nullptr);
+          return SHRPX_ERR_NETWORK;
+        case DNSResolverStatus::RUNNING:
+          dns_query_ = std::move(dns_query);
+          return 0;
+        case DNSResolverStatus::OK:
+          break;
+        default:
+          assert(0);
+        }
+      } else {
+        switch (dns_query_->status) {
+        case DNSResolverStatus::ERROR:
+          dns_query_.reset();
+          downstream_failure(addr_, nullptr);
+          return SHRPX_ERR_NETWORK;
+        case DNSResolverStatus::OK:
+          dns_query_.reset();
+          break;
+        default:
+          assert(0);
+        }
+      }
+
+      raddr = resolved_addr_.get();
+      util::set_port(*resolved_addr_, addr_->port);
+    } else {
+      raddr = &addr_->addr;
+    }
+
+    conn_.fd = util::create_nonblock_socket(raddr->su.storage.ss_family);
+
+    if (conn_.fd == -1) {
+      auto error = errno;
+      DCLOG(WARN, this) << "socket() failed; addr="
+                        << util::to_numeric_addr(raddr) << ", errno=" << error;
+
+      worker_blocker->on_failure();
+
+      return SHRPX_ERR_NETWORK;
+    }
+
+    worker_blocker->on_success();
+
+    rv = connect(conn_.fd, &raddr->su.sa, raddr->len);
+    if (rv != 0 && errno != EINPROGRESS) {
+      auto error = errno;
+      DCLOG(WARN, this) << "connect() failed; addr="
+                        << util::to_numeric_addr(raddr) << ", errno=" << error;
+
+      downstream_failure(addr_, raddr);
+
+      return SHRPX_ERR_NETWORK;
+    }
+
+    if (LOG_ENABLED(INFO)) {
+      DCLOG(INFO, this) << "Connecting to downstream server";
+    }
+
+    raddr_ = raddr;
+
+    if (addr_->tls) {
+      assert(ssl_ctx_);
+
+      auto ssl = tls::create_ssl(ssl_ctx_);
+      if (!ssl) {
+        return -1;
+      }
+
+      tls::setup_downstream_http1_alpn(ssl);
+
+      conn_.set_ssl(ssl);
+      conn_.tls.client_session_cache = &addr_->tls_session_cache;
+
+      auto sni_name =
+          addr_->sni.empty() ? StringRef{addr_->host} : StringRef{addr_->sni};
+      if (!util::numeric_host(sni_name.c_str())) {
+        SSL_set_tlsext_host_name(conn_.tls.ssl, sni_name.c_str());
+      }
+
+      auto session = tls::reuse_tls_session(addr_->tls_session_cache);
+      if (session) {
+        SSL_set_session(conn_.tls.ssl, session);
+        SSL_SESSION_free(session);
+      }
+
+      conn_.prepare_client_handshake();
+    }
+
+    ev_io_set(&conn_.wev, conn_.fd, EV_WRITE);
+    ev_io_set(&conn_.rev, conn_.fd, EV_READ);
+
+    conn_.wlimit.startw();
+
+    conn_.wt.repeat = downstreamconf.timeout.connect;
+    ev_timer_again(conn_.loop, &conn_.wt);
+  } else {
+    // we may set read timer cb to idle_timeoutcb.  Reset again.
+    ev_set_cb(&conn_.rt, timeoutcb);
+    if (conn_.read_timeout < group_->shared_addr->timeout.read) {
+      conn_.read_timeout = group_->shared_addr->timeout.read;
+      conn_.last_read = ev_now(conn_.loop);
+    } else {
+      conn_.again_rt(group_->shared_addr->timeout.read);
+    }
+
+    ev_set_cb(&conn_.rev, readcb);
+
+    on_write_ = &HttpDownstreamConnection::write_first;
+    first_write_done_ = false;
+    request_header_written_ = false;
+  }
+
+  llhttp_init(&response_htp_, HTTP_RESPONSE, &htp_hooks);
+  response_htp_.data = downstream_;
+
+  return 0;
+}
+
+int HttpDownstreamConnection::push_request_headers() {
+  if (request_header_written_) {
+    signal_write();
+    return 0;
+  }
+
+  const auto &downstream_hostport = addr_->hostport;
+  const auto &req = downstream_->request();
+
+  auto &balloc = downstream_->get_block_allocator();
+
+  auto connect_method = req.regular_connect_method();
+
+  auto config = get_config();
+  auto &httpconf = config->http;
+
+  request_header_written_ = true;
+
+  // For HTTP/1.0 request, there is no authority in request.  In that
+  // case, we use backend server's host nonetheless.
+  auto authority = StringRef(downstream_hostport);
+  auto no_host_rewrite =
+      httpconf.no_host_rewrite || config->http2_proxy || connect_method;
+
+  if (no_host_rewrite && !req.authority.empty()) {
+    authority = req.authority;
+  }
+
+  downstream_->set_request_downstream_host(authority);
+
+  auto buf = downstream_->get_request_buf();
+
+  // Assume that method and request path do not contain \r\n.
+  auto meth = http2::to_method_string(
+      req.connect_proto == ConnectProto::WEBSOCKET ? HTTP_GET : req.method);
+  buf->append(meth);
+  buf->append(' ');
+
+  if (connect_method) {
+    buf->append(authority);
+  } else if (config->http2_proxy) {
+    // Construct absolute-form request target because we are going to
+    // send a request to a HTTP/1 proxy.
+    assert(!req.scheme.empty());
+    buf->append(req.scheme);
+    buf->append("://");
+    buf->append(authority);
+    buf->append(req.path);
+  } else if (req.method == HTTP_OPTIONS && req.path.empty()) {
+    // Server-wide OPTIONS
+    buf->append("*");
+  } else {
+    buf->append(req.path);
+  }
+  buf->append(" HTTP/1.1\r\nHost: ");
+  buf->append(authority);
+  buf->append("\r\n");
+
+  auto &fwdconf = httpconf.forwarded;
+  auto &xffconf = httpconf.xff;
+  auto &xfpconf = httpconf.xfp;
+  auto &earlydataconf = httpconf.early_data;
+
+  uint32_t build_flags =
+      (fwdconf.strip_incoming ? http2::HDOP_STRIP_FORWARDED : 0) |
+      (xffconf.strip_incoming ? http2::HDOP_STRIP_X_FORWARDED_FOR : 0) |
+      (xfpconf.strip_incoming ? http2::HDOP_STRIP_X_FORWARDED_PROTO : 0) |
+      (earlydataconf.strip_incoming ? http2::HDOP_STRIP_EARLY_DATA : 0) |
+      ((req.http_major == 3 || req.http_major == 2)
+           ? http2::HDOP_STRIP_SEC_WEBSOCKET_KEY
+           : 0);
+
+  http2::build_http1_headers_from_headers(buf, req.fs.headers(), build_flags);
+
+  auto cookie = downstream_->assemble_request_cookie();
+  if (!cookie.empty()) {
+    buf->append("Cookie: ");
+    buf->append(cookie);
+    buf->append("\r\n");
+  }
+
+  // set transfer-encoding only when content-length is unknown and
+  // request body is expected.
+  if (req.method != HTTP_CONNECT && req.http2_expect_body &&
+      req.fs.content_length == -1) {
+    downstream_->set_chunked_request(true);
+    buf->append("Transfer-Encoding: chunked\r\n");
+  }
+
+  if (req.connect_proto == ConnectProto::WEBSOCKET) {
+    if (req.http_major == 3 || req.http_major == 2) {
+      std::array<uint8_t, 16> nonce;
+      if (RAND_bytes(nonce.data(), nonce.size()) != 1) {
+        return -1;
+      }
+      auto iov = make_byte_ref(balloc, base64::encode_length(nonce.size()) + 1);
+      auto p = base64::encode(std::begin(nonce), std::end(nonce), iov.base);
+      *p = '\0';
+      auto key = StringRef{iov.base, p};
+      downstream_->set_ws_key(key);
+
+      buf->append("Sec-Websocket-Key: ");
+      buf->append(key);
+      buf->append("\r\n");
+    }
+
+    buf->append("Upgrade: websocket\r\nConnection: Upgrade\r\n");
+  } else if (!connect_method && req.upgrade_request) {
+    auto connection = req.fs.header(http2::HD_CONNECTION);
+    if (connection) {
+      buf->append("Connection: ");
+      buf->append((*connection).value);
+      buf->append("\r\n");
+    }
+
+    auto upgrade = req.fs.header(http2::HD_UPGRADE);
+    if (upgrade) {
+      buf->append("Upgrade: ");
+      buf->append((*upgrade).value);
+      buf->append("\r\n");
+    }
+  } else if (req.connection_close) {
+    buf->append("Connection: close\r\n");
+  }
+
+  auto upstream = downstream_->get_upstream();
+  auto handler = upstream->get_client_handler();
+
+#if OPENSSL_1_1_1_API
+  auto conn = handler->get_connection();
+
+  if (conn->tls.ssl && !SSL_is_init_finished(conn->tls.ssl)) {
+    buf->append("Early-Data: 1\r\n");
+  }
+#endif // OPENSSL_1_1_1_API
+
+  auto fwd =
+      fwdconf.strip_incoming ? nullptr : req.fs.header(http2::HD_FORWARDED);
+
+  if (fwdconf.params) {
+    auto params = fwdconf.params;
+
+    if (config->http2_proxy || connect_method) {
+      params &= ~FORWARDED_PROTO;
+    }
+
+    auto value = http::create_forwarded(
+        balloc, params, handler->get_forwarded_by(),
+        handler->get_forwarded_for(), req.authority, req.scheme);
+
+    if (fwd || !value.empty()) {
+      buf->append("Forwarded: ");
+      if (fwd) {
+        buf->append(fwd->value);
+
+        if (!value.empty()) {
+          buf->append(", ");
+        }
+      }
+      buf->append(value);
+      buf->append("\r\n");
+    }
+  } else if (fwd) {
+    buf->append("Forwarded: ");
+    buf->append(fwd->value);
+    buf->append("\r\n");
+  }
+
+  auto xff = xffconf.strip_incoming ? nullptr
+                                    : req.fs.header(http2::HD_X_FORWARDED_FOR);
+
+  if (xffconf.add) {
+    buf->append("X-Forwarded-For: ");
+    if (xff) {
+      buf->append((*xff).value);
+      buf->append(", ");
+    }
+    buf->append(client_handler_->get_ipaddr());
+    buf->append("\r\n");
+  } else if (xff) {
+    buf->append("X-Forwarded-For: ");
+    buf->append((*xff).value);
+    buf->append("\r\n");
+  }
+  if (!config->http2_proxy && !connect_method) {
+    auto xfp = xfpconf.strip_incoming
+                   ? nullptr
+                   : req.fs.header(http2::HD_X_FORWARDED_PROTO);
+
+    if (xfpconf.add) {
+      buf->append("X-Forwarded-Proto: ");
+      if (xfp) {
+        buf->append((*xfp).value);
+        buf->append(", ");
+      }
+      assert(!req.scheme.empty());
+      buf->append(req.scheme);
+      buf->append("\r\n");
+    } else if (xfp) {
+      buf->append("X-Forwarded-Proto: ");
+      buf->append((*xfp).value);
+      buf->append("\r\n");
+    }
+  }
+  auto via = req.fs.header(http2::HD_VIA);
+  if (httpconf.no_via) {
+    if (via) {
+      buf->append("Via: ");
+      buf->append((*via).value);
+      buf->append("\r\n");
+    }
+  } else {
+    buf->append("Via: ");
+    if (via) {
+      buf->append((*via).value);
+      buf->append(", ");
+    }
+    std::array<char, 16> viabuf;
+    auto end = http::create_via_header_value(viabuf.data(), req.http_major,
+                                             req.http_minor);
+    buf->append(viabuf.data(), end - viabuf.data());
+    buf->append("\r\n");
+  }
+
+  for (auto &p : httpconf.add_request_headers) {
+    buf->append(p.name);
+    buf->append(": ");
+    buf->append(p.value);
+    buf->append("\r\n");
+  }
+
+  buf->append("\r\n");
+
+  if (LOG_ENABLED(INFO)) {
+    std::string nhdrs;
+    for (auto chunk = buf->head; chunk; chunk = chunk->next) {
+      nhdrs.append(chunk->pos, chunk->last);
+    }
+    if (log_config()->errorlog_tty) {
+      nhdrs = http::colorizeHeaders(nhdrs.c_str());
+    }
+    DCLOG(INFO, this) << "HTTP request headers. stream_id="
+                      << downstream_->get_stream_id() << "\n"
+                      << nhdrs;
+  }
+
+  // Don't call signal_write() if we anticipate request body.  We call
+  // signal_write() when we received request body chunk, and it
+  // enables us to send headers and data in one writev system call.
+  if (req.method == HTTP_CONNECT ||
+      downstream_->get_blocked_request_buf()->rleft() ||
+      (!req.http2_expect_body && req.fs.content_length == 0) ||
+      downstream_->get_expect_100_continue()) {
+    signal_write();
+  }
+
+  return 0;
+}
+
+int HttpDownstreamConnection::process_blocked_request_buf() {
+  auto src = downstream_->get_blocked_request_buf();
+
+  if (src->rleft()) {
+    auto dest = downstream_->get_request_buf();
+    auto chunked = downstream_->get_chunked_request();
+    if (chunked) {
+      auto chunk_size_hex = util::utox(src->rleft());
+      dest->append(chunk_size_hex);
+      dest->append("\r\n");
+    }
+
+    src->copy(*dest);
+
+    if (chunked) {
+      dest->append("\r\n");
+    }
+  }
+
+  if (downstream_->get_blocked_request_data_eof() &&
+      downstream_->get_chunked_request()) {
+    end_upload_data_chunk();
+  }
+
+  return 0;
+}
+
+int HttpDownstreamConnection::push_upload_data_chunk(const uint8_t *data,
+                                                     size_t datalen) {
+  if (!downstream_->get_request_header_sent()) {
+    auto output = downstream_->get_blocked_request_buf();
+    auto &req = downstream_->request();
+    output->append(data, datalen);
+    req.unconsumed_body_length += datalen;
+    if (request_header_written_) {
+      signal_write();
+    }
+    return 0;
+  }
+
+  auto chunked = downstream_->get_chunked_request();
+  auto output = downstream_->get_request_buf();
+
+  if (chunked) {
+    auto chunk_size_hex = util::utox(datalen);
+    output->append(chunk_size_hex);
+    output->append("\r\n");
+  }
+
+  output->append(data, datalen);
+
+  if (chunked) {
+    output->append("\r\n");
+  }
+
+  signal_write();
+
+  return 0;
+}
+
+int HttpDownstreamConnection::end_upload_data() {
+  if (!downstream_->get_request_header_sent()) {
+    downstream_->set_blocked_request_data_eof(true);
+    if (request_header_written_) {
+      signal_write();
+    }
+    return 0;
+  }
+
+  signal_write();
+
+  if (!downstream_->get_chunked_request()) {
+    return 0;
+  }
+
+  end_upload_data_chunk();
+
+  return 0;
+}
+
+void HttpDownstreamConnection::end_upload_data_chunk() {
+  const auto &req = downstream_->request();
+
+  auto output = downstream_->get_request_buf();
+  const auto &trailers = req.fs.trailers();
+  if (trailers.empty()) {
+    output->append("0\r\n\r\n");
+  } else {
+    output->append("0\r\n");
+    http2::build_http1_headers_from_headers(output, trailers,
+                                            http2::HDOP_STRIP_ALL);
+    output->append("\r\n");
+  }
+}
+
+namespace {
+void remove_from_pool(HttpDownstreamConnection *dconn) {
+  auto addr = dconn->get_addr();
+  auto &dconn_pool = addr->dconn_pool;
+  dconn_pool->remove_downstream_connection(dconn);
+}
+} // namespace
+
+namespace {
+void idle_readcb(struct ev_loop *loop, ev_io *w, int revents) {
+  auto conn = static_cast<Connection *>(w->data);
+  auto dconn = static_cast<HttpDownstreamConnection *>(conn->data);
+  if (LOG_ENABLED(INFO)) {
+    DCLOG(INFO, dconn) << "Idle connection EOF";
+  }
+
+  remove_from_pool(dconn);
+  // dconn was deleted
+}
+} // namespace
+
+namespace {
+void idle_timeoutcb(struct ev_loop *loop, ev_timer *w, int revents) {
+  auto conn = static_cast<Connection *>(w->data);
+  auto dconn = static_cast<HttpDownstreamConnection *>(conn->data);
+
+  if (w == &conn->rt && !conn->expired_rt()) {
+    return;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    DCLOG(INFO, dconn) << "Idle connection timeout";
+  }
+
+  remove_from_pool(dconn);
+  // dconn was deleted
+}
+} // namespace
+
+void HttpDownstreamConnection::detach_downstream(Downstream *downstream) {
+  if (LOG_ENABLED(INFO)) {
+    DCLOG(INFO, this) << "Detaching from DOWNSTREAM:" << downstream;
+  }
+  downstream_ = nullptr;
+
+  ev_set_cb(&conn_.rev, idle_readcb);
+  ioctrl_.force_resume_read();
+
+  auto &downstreamconf = *worker_->get_downstream_config();
+
+  ev_set_cb(&conn_.rt, idle_timeoutcb);
+  if (conn_.read_timeout < downstreamconf.timeout.idle_read) {
+    conn_.read_timeout = downstreamconf.timeout.idle_read;
+    conn_.last_read = ev_now(conn_.loop);
+  } else {
+    conn_.again_rt(downstreamconf.timeout.idle_read);
+  }
+
+  conn_.wlimit.stopw();
+  ev_timer_stop(conn_.loop, &conn_.wt);
+}
+
+void HttpDownstreamConnection::pause_read(IOCtrlReason reason) {
+  ioctrl_.pause_read(reason);
+}
+
+int HttpDownstreamConnection::resume_read(IOCtrlReason reason,
+                                          size_t consumed) {
+  auto &downstreamconf = *worker_->get_downstream_config();
+
+  if (downstream_->get_response_buf()->rleft() <=
+      downstreamconf.request_buffer_size / 2) {
+    ioctrl_.resume_read(reason);
+  }
+
+  return 0;
+}
+
+void HttpDownstreamConnection::force_resume_read() {
+  ioctrl_.force_resume_read();
+}
+
+namespace {
+int htp_msg_begincb(llhttp_t *htp) {
+  auto downstream = static_cast<Downstream *>(htp->data);
+
+  if (downstream->get_response_state() != DownstreamState::INITIAL) {
+    return -1;
+  }
+
+  return 0;
+}
+} // namespace
+
+namespace {
+int htp_hdrs_completecb(llhttp_t *htp) {
+  auto downstream = static_cast<Downstream *>(htp->data);
+  auto upstream = downstream->get_upstream();
+  auto handler = upstream->get_client_handler();
+  const auto &req = downstream->request();
+  auto &resp = downstream->response();
+  int rv;
+
+  auto &balloc = downstream->get_block_allocator();
+
+  for (auto &kv : resp.fs.headers()) {
+    kv.value = util::rstrip(balloc, kv.value);
+  }
+
+  auto config = get_config();
+  auto &loggingconf = config->logging;
+
+  resp.http_status = htp->status_code;
+  resp.http_major = htp->http_major;
+  resp.http_minor = htp->http_minor;
+
+  if (resp.http_major > 1 || req.http_minor > 1) {
+    resp.http_major = 1;
+    resp.http_minor = 1;
+    return -1;
+  }
+
+  auto dconn = downstream->get_downstream_connection();
+
+  downstream->set_downstream_addr_group(dconn->get_downstream_addr_group());
+  downstream->set_addr(dconn->get_addr());
+
+  // Server MUST NOT send Transfer-Encoding with a status code 1xx or
+  // 204.  Also server MUST NOT send Transfer-Encoding with a status
+  // code 2xx to a CONNECT request.  Same holds true with
+  // Content-Length.
+  if (resp.http_status == 204) {
+    if (resp.fs.header(http2::HD_TRANSFER_ENCODING)) {
+      return -1;
+    }
+    // Some server send content-length: 0 for 204.  Until they get
+    // fixed, we accept, but ignore it.
+
+    // Calling parse_content_length() detects duplicated
+    // content-length header fields.
+    if (resp.fs.parse_content_length() != 0) {
+      return -1;
+    }
+    if (resp.fs.content_length == 0) {
+      resp.fs.erase_content_length_and_transfer_encoding();
+    } else if (resp.fs.content_length != -1) {
+      return -1;
+    }
+  } else if (resp.http_status / 100 == 1 ||
+             (resp.http_status / 100 == 2 && req.method == HTTP_CONNECT)) {
+    // Server MUST NOT send Content-Length and Transfer-Encoding in
+    // these responses.
+    resp.fs.erase_content_length_and_transfer_encoding();
+  } else if (resp.fs.parse_content_length() != 0) {
+    downstream->set_response_state(DownstreamState::MSG_BAD_HEADER);
+    return -1;
+  }
+
+  // Check upgrade before processing non-final response, since if
+  // upgrade succeeded, 101 response is treated as final in nghttpx.
+  downstream->check_upgrade_fulfilled_http1();
+
+  if (downstream->get_non_final_response()) {
+    // Reset content-length because we reuse same Downstream for the
+    // next response.
+    resp.fs.content_length = -1;
+    // For non-final response code, we just call
+    // on_downstream_header_complete() without changing response
+    // state.
+    rv = upstream->on_downstream_header_complete(downstream);
+
+    if (rv != 0) {
+      return -1;
+    }
+
+    // Ignore response body for non-final response.
+    return 1;
+  }
+
+  resp.connection_close = !llhttp_should_keep_alive(htp);
+  downstream->set_response_state(DownstreamState::HEADER_COMPLETE);
+  downstream->inspect_http1_response();
+  if (downstream->get_upgraded()) {
+    // content-length must be ignored for upgraded connection.
+    resp.fs.content_length = -1;
+    resp.connection_close = true;
+    // transfer-encoding not applied to upgraded connection
+    downstream->set_chunked_response(false);
+  } else if (http2::legacy_http1(req.http_major, req.http_minor)) {
+    if (resp.fs.content_length == -1) {
+      resp.connection_close = true;
+    }
+    downstream->set_chunked_response(false);
+  } else if (!downstream->expect_response_body()) {
+    downstream->set_chunked_response(false);
+  }
+
+  if (loggingconf.access.write_early && downstream->accesslog_ready()) {
+    handler->write_accesslog(downstream);
+    downstream->set_accesslog_written(true);
+  }
+
+  if (upstream->on_downstream_header_complete(downstream) != 0) {
+    return -1;
+  }
+
+  if (downstream->get_upgraded()) {
+    // Upgrade complete, read until EOF in both ends
+    if (upstream->resume_read(SHRPX_NO_BUFFER, downstream, 0) != 0) {
+      return -1;
+    }
+    downstream->set_request_state(DownstreamState::HEADER_COMPLETE);
+    if (LOG_ENABLED(INFO)) {
+      LOG(INFO) << "HTTP upgrade success. stream_id="
+                << downstream->get_stream_id();
+    }
+  }
+
+  // Ignore the response body. HEAD response may contain
+  // Content-Length or Transfer-Encoding: chunked.  Some server send
+  // 304 status code with nonzero Content-Length, but without response
+  // body. See
+  // https://tools.ietf.org/html/rfc7230#section-3.3
+
+  // TODO It seems that the cases other than HEAD are handled by
+  // llhttp.  Need test.
+  return !http2::expect_response_body(req.method, resp.http_status);
+}
+} // namespace
+
+namespace {
+int ensure_header_field_buffer(const Downstream *downstream,
+                               const HttpConfig &httpconf, size_t len) {
+  auto &resp = downstream->response();
+
+  if (resp.fs.buffer_size() + len > httpconf.response_header_field_buffer) {
+    if (LOG_ENABLED(INFO)) {
+      DLOG(INFO, downstream) << "Too large header header field size="
+                             << resp.fs.buffer_size() + len;
+    }
+    return -1;
+  }
+
+  return 0;
+}
+} // namespace
+
+namespace {
+int ensure_max_header_fields(const Downstream *downstream,
+                             const HttpConfig &httpconf) {
+  auto &resp = downstream->response();
+
+  if (resp.fs.num_fields() >= httpconf.max_response_header_fields) {
+    if (LOG_ENABLED(INFO)) {
+      DLOG(INFO, downstream)
+          << "Too many header field num=" << resp.fs.num_fields() + 1;
+    }
+    return -1;
+  }
+
+  return 0;
+}
+} // namespace
+
+namespace {
+int htp_hdr_keycb(llhttp_t *htp, const char *data, size_t len) {
+  auto downstream = static_cast<Downstream *>(htp->data);
+  auto &resp = downstream->response();
+  auto &httpconf = get_config()->http;
+
+  if (ensure_header_field_buffer(downstream, httpconf, len) != 0) {
+    return -1;
+  }
+
+  if (downstream->get_response_state() == DownstreamState::INITIAL) {
+    if (resp.fs.header_key_prev()) {
+      resp.fs.append_last_header_key(data, len);
+    } else {
+      if (ensure_max_header_fields(downstream, httpconf) != 0) {
+        return -1;
+      }
+      resp.fs.alloc_add_header_name(StringRef{data, len});
+    }
+  } else {
+    // trailer part
+    if (resp.fs.trailer_key_prev()) {
+      resp.fs.append_last_trailer_key(data, len);
+    } else {
+      if (ensure_max_header_fields(downstream, httpconf) != 0) {
+        // Could not ignore this trailer field easily, since we may
+        // get its value in htp_hdr_valcb, and it will be added to
+        // wrong place or crash if trailer fields are currently empty.
+        return -1;
+      }
+      resp.fs.alloc_add_trailer_name(StringRef{data, len});
+    }
+  }
+  return 0;
+}
+} // namespace
+
+namespace {
+int htp_hdr_valcb(llhttp_t *htp, const char *data, size_t len) {
+  auto downstream = static_cast<Downstream *>(htp->data);
+  auto &resp = downstream->response();
+  auto &httpconf = get_config()->http;
+
+  if (ensure_header_field_buffer(downstream, httpconf, len) != 0) {
+    return -1;
+  }
+
+  if (downstream->get_response_state() == DownstreamState::INITIAL) {
+    resp.fs.append_last_header_value(data, len);
+  } else {
+    resp.fs.append_last_trailer_value(data, len);
+  }
+  return 0;
+}
+} // namespace
+
+namespace {
+int htp_bodycb(llhttp_t *htp, const char *data, size_t len) {
+  auto downstream = static_cast<Downstream *>(htp->data);
+  auto &resp = downstream->response();
+
+  resp.recv_body_length += len;
+
+  return downstream->get_upstream()->on_downstream_body(
+      downstream, reinterpret_cast<const uint8_t *>(data), len, true);
+}
+} // namespace
+
+namespace {
+int htp_msg_completecb(llhttp_t *htp) {
+  auto downstream = static_cast<Downstream *>(htp->data);
+  auto &resp = downstream->response();
+  auto &balloc = downstream->get_block_allocator();
+
+  for (auto &kv : resp.fs.trailers()) {
+    kv.value = util::rstrip(balloc, kv.value);
+  }
+
+  // llhttp does not treat "200 connection established" response
+  // against CONNECT request, and in that case, this function is not
+  // called.  But if HTTP Upgrade is made (e.g., WebSocket), this
+  // function is called, and llhttp_execute() returns just after that.
+  if (downstream->get_upgraded()) {
+    return 0;
+  }
+
+  if (downstream->get_non_final_response()) {
+    downstream->reset_response();
+
+    return 0;
+  }
+
+  downstream->set_response_state(DownstreamState::MSG_COMPLETE);
+  // Block reading another response message from (broken?)
+  // server. This callback is not called if the connection is
+  // tunneled.
+  downstream->pause_read(SHRPX_MSG_BLOCK);
+  return downstream->get_upstream()->on_downstream_body_complete(downstream);
+}
+} // namespace
+
+int HttpDownstreamConnection::write_first() {
+  int rv;
+
+  process_blocked_request_buf();
+
+  if (conn_.tls.ssl) {
+    rv = write_tls();
+  } else {
+    rv = write_clear();
+  }
+
+  if (rv != 0) {
+    return SHRPX_ERR_RETRY;
+  }
+
+  if (conn_.tls.ssl) {
+    on_write_ = &HttpDownstreamConnection::write_tls;
+  } else {
+    on_write_ = &HttpDownstreamConnection::write_clear;
+  }
+
+  first_write_done_ = true;
+  downstream_->set_request_header_sent(true);
+
+  auto buf = downstream_->get_blocked_request_buf();
+  buf->reset();
+
+  // upstream->resume_read() might be called in
+  // write_tls()/write_clear(), but before blocked_request_buf_ is
+  // reset.  So upstream read might still be blocked.  Let's do it
+  // again here.
+  auto input = downstream_->get_request_buf();
+  if (input->rleft() == 0) {
+    auto upstream = downstream_->get_upstream();
+    auto &req = downstream_->request();
+
+    upstream->resume_read(SHRPX_NO_BUFFER, downstream_,
+                          req.unconsumed_body_length);
+  }
+
+  return 0;
+}
+
+int HttpDownstreamConnection::read_clear() {
+  conn_.last_read = ev_now(conn_.loop);
+
+  std::array<uint8_t, 16_k> buf;
+  int rv;
+
+  for (;;) {
+    auto nread = conn_.read_clear(buf.data(), buf.size());
+    if (nread == 0) {
+      return 0;
+    }
+
+    if (nread < 0) {
+      if (nread == SHRPX_ERR_EOF && !downstream_->get_upgraded()) {
+        auto htperr = llhttp_finish(&response_htp_);
+        if (htperr != HPE_OK) {
+          if (LOG_ENABLED(INFO)) {
+            DCLOG(INFO, this) << "HTTP response ended prematurely: "
+                              << llhttp_errno_name(htperr);
+          }
+
+          return -1;
+        }
+      }
+
+      return nread;
+    }
+
+    rv = process_input(buf.data(), nread);
+    if (rv != 0) {
+      return rv;
+    }
+
+    if (!ev_is_active(&conn_.rev)) {
+      return 0;
+    }
+  }
+}
+
+int HttpDownstreamConnection::write_clear() {
+  conn_.last_read = ev_now(conn_.loop);
+
+  auto upstream = downstream_->get_upstream();
+  auto input = downstream_->get_request_buf();
+
+  std::array<struct iovec, MAX_WR_IOVCNT> iov;
+
+  while (input->rleft() > 0) {
+    auto iovcnt = input->riovec(iov.data(), iov.size());
+
+    auto nwrite = conn_.writev_clear(iov.data(), iovcnt);
+
+    if (nwrite == 0) {
+      return 0;
+    }
+
+    if (nwrite < 0) {
+      if (!first_write_done_) {
+        return nwrite;
+      }
+      // We may have pending data in receive buffer which may contain
+      // part of response body.  So keep reading.  Invoke read event
+      // to get read(2) error just in case.
+      ev_feed_event(conn_.loop, &conn_.rev, EV_READ);
+      on_write_ = &HttpDownstreamConnection::noop;
+      reusable_ = false;
+      break;
+    }
+
+    input->drain(nwrite);
+  }
+
+  conn_.wlimit.stopw();
+  ev_timer_stop(conn_.loop, &conn_.wt);
+
+  if (input->rleft() == 0) {
+    auto &req = downstream_->request();
+
+    upstream->resume_read(SHRPX_NO_BUFFER, downstream_,
+                          req.unconsumed_body_length);
+  }
+
+  return 0;
+}
+
+int HttpDownstreamConnection::tls_handshake() {
+  ERR_clear_error();
+
+  conn_.last_read = ev_now(conn_.loop);
+
+  auto rv = conn_.tls_handshake();
+  if (rv == SHRPX_ERR_INPROGRESS) {
+    return 0;
+  }
+
+  if (rv < 0) {
+    downstream_failure(addr_, raddr_);
+
+    return rv;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    DCLOG(INFO, this) << "SSL/TLS handshake completed";
+  }
+
+  if (!get_config()->tls.insecure &&
+      tls::check_cert(conn_.tls.ssl, addr_, raddr_) != 0) {
+    downstream_failure(addr_, raddr_);
+
+    return -1;
+  }
+
+  auto &connect_blocker = addr_->connect_blocker;
+
+  signal_write_ = &HttpDownstreamConnection::actual_signal_write;
+
+  connect_blocker->on_success();
+
+  ev_set_cb(&conn_.rt, timeoutcb);
+  ev_set_cb(&conn_.wt, timeoutcb);
+
+  on_read_ = &HttpDownstreamConnection::read_tls;
+  on_write_ = &HttpDownstreamConnection::write_first;
+
+  // TODO Check negotiated ALPN
+
+  return on_write();
+}
+
+int HttpDownstreamConnection::read_tls() {
+  conn_.last_read = ev_now(conn_.loop);
+
+  ERR_clear_error();
+
+  std::array<uint8_t, 16_k> buf;
+  int rv;
+
+  for (;;) {
+    auto nread = conn_.read_tls(buf.data(), buf.size());
+    if (nread == 0) {
+      return 0;
+    }
+
+    if (nread < 0) {
+      if (nread == SHRPX_ERR_EOF && !downstream_->get_upgraded()) {
+        auto htperr = llhttp_finish(&response_htp_);
+        if (htperr != HPE_OK) {
+          if (LOG_ENABLED(INFO)) {
+            DCLOG(INFO, this) << "HTTP response ended prematurely: "
+                              << llhttp_errno_name(htperr);
+          }
+
+          return -1;
+        }
+      }
+
+      return nread;
+    }
+
+    rv = process_input(buf.data(), nread);
+    if (rv != 0) {
+      return rv;
+    }
+
+    if (!ev_is_active(&conn_.rev)) {
+      return 0;
+    }
+  }
+}
+
+int HttpDownstreamConnection::write_tls() {
+  conn_.last_read = ev_now(conn_.loop);
+
+  ERR_clear_error();
+
+  auto upstream = downstream_->get_upstream();
+  auto input = downstream_->get_request_buf();
+
+  struct iovec iov;
+
+  while (input->rleft() > 0) {
+    auto iovcnt = input->riovec(&iov, 1);
+    if (iovcnt != 1) {
+      assert(0);
+      return -1;
+    }
+    auto nwrite = conn_.write_tls(iov.iov_base, iov.iov_len);
+
+    if (nwrite == 0) {
+      return 0;
+    }
+
+    if (nwrite < 0) {
+      if (!first_write_done_) {
+        return nwrite;
+      }
+      // We may have pending data in receive buffer which may contain
+      // part of response body.  So keep reading.  Invoke read event
+      // to get read(2) error just in case.
+      ev_feed_event(conn_.loop, &conn_.rev, EV_READ);
+      on_write_ = &HttpDownstreamConnection::noop;
+      reusable_ = false;
+      break;
+    }
+
+    input->drain(nwrite);
+  }
+
+  conn_.wlimit.stopw();
+  ev_timer_stop(conn_.loop, &conn_.wt);
+
+  if (input->rleft() == 0) {
+    auto &req = downstream_->request();
+
+    upstream->resume_read(SHRPX_NO_BUFFER, downstream_,
+                          req.unconsumed_body_length);
+  }
+
+  return 0;
+}
+
+int HttpDownstreamConnection::process_input(const uint8_t *data,
+                                            size_t datalen) {
+  int rv;
+
+  if (downstream_->get_upgraded()) {
+    // For upgraded connection, just pass data to the upstream.
+    rv = downstream_->get_upstream()->on_downstream_body(downstream_, data,
+                                                         datalen, true);
+    if (rv != 0) {
+      return rv;
+    }
+
+    if (downstream_->response_buf_full()) {
+      downstream_->pause_read(SHRPX_NO_BUFFER);
+      return 0;
+    }
+
+    return 0;
+  }
+
+  auto htperr = llhttp_execute(&response_htp_,
+                               reinterpret_cast<const char *>(data), datalen);
+  auto nproc =
+      htperr == HPE_OK
+          ? datalen
+          : static_cast<size_t>(reinterpret_cast<const uint8_t *>(
+                                    llhttp_get_error_pos(&response_htp_)) -
+                                data);
+
+  if (htperr != HPE_OK &&
+      (!downstream_->get_upgraded() || htperr != HPE_PAUSED_UPGRADE)) {
+    // Handling early return (in other words, response was hijacked by
+    // mruby scripting).
+    if (downstream_->get_response_state() == DownstreamState::MSG_COMPLETE) {
+      return SHRPX_ERR_DCONN_CANCELED;
+    }
+
+    if (LOG_ENABLED(INFO)) {
+      DCLOG(INFO, this) << "HTTP parser failure: "
+                        << "(" << llhttp_errno_name(htperr) << ") "
+                        << llhttp_get_error_reason(&response_htp_);
+    }
+
+    return -1;
+  }
+
+  if (downstream_->get_upgraded()) {
+    if (nproc < datalen) {
+      // Data from data + nproc are for upgraded protocol.
+      rv = downstream_->get_upstream()->on_downstream_body(
+          downstream_, data + nproc, datalen - nproc, true);
+      if (rv != 0) {
+        return rv;
+      }
+
+      if (downstream_->response_buf_full()) {
+        downstream_->pause_read(SHRPX_NO_BUFFER);
+        return 0;
+      }
+    }
+    return 0;
+  }
+
+  if (downstream_->response_buf_full()) {
+    downstream_->pause_read(SHRPX_NO_BUFFER);
+    return 0;
+  }
+
+  return 0;
+}
+
+int HttpDownstreamConnection::connected() {
+  auto &connect_blocker = addr_->connect_blocker;
+
+  auto sock_error = util::get_socket_error(conn_.fd);
+  if (sock_error != 0) {
+    conn_.wlimit.stopw();
+
+    DCLOG(WARN, this) << "Backend connect failed; addr="
+                      << util::to_numeric_addr(raddr_)
+                      << ": errno=" << sock_error;
+
+    downstream_failure(addr_, raddr_);
+
+    return -1;
+  }
+
+  if (LOG_ENABLED(INFO)) {
+    DCLOG(INFO, this) << "Connected to downstream host";
+  }
+
+  // Reset timeout for write.  Previously, we set timeout for connect.
+  conn_.wt.repeat = group_->shared_addr->timeout.write;
+  ev_timer_again(conn_.loop, &conn_.wt);
+
+  conn_.rlimit.startw();
+  conn_.again_rt();
+
+  ev_set_cb(&conn_.wev, writecb);
+
+  if (conn_.tls.ssl) {
+    on_read_ = &HttpDownstreamConnection::tls_handshake;
+    on_write_ = &HttpDownstreamConnection::tls_handshake;
+
+    return 0;
+  }
+
+  signal_write_ = &HttpDownstreamConnection::actual_signal_write;
+
+  connect_blocker->on_success();
+
+  ev_set_cb(&conn_.rt, timeoutcb);
+  ev_set_cb(&conn_.wt, timeoutcb);
+
+  on_read_ = &HttpDownstreamConnection::read_clear;
+  on_write_ = &HttpDownstreamConnection::write_first;
+
+  return 0;
+}
+
+int HttpDownstreamConnection::on_read() { return on_read_(*this); }
+
+int HttpDownstreamConnection::on_write() { return on_write_(*this); }
+
+void HttpDownstreamConnection::on_upstream_change(Upstream *upstream) {}
+
+void HttpDownstreamConnection::signal_write() { signal_write_(*this); }
+
+int HttpDownstreamConnection::actual_signal_write() {
+  ev_feed_event(conn_.loop, &conn_.wev, EV_WRITE);
+  return 0;
+}
+
+int HttpDownstreamConnection::noop() { return 0; }
+
+const std::shared_ptr<DownstreamAddrGroup> &
+HttpDownstreamConnection::get_downstream_addr_group() const {
+  return group_;
+}
+
+DownstreamAddr *HttpDownstreamConnection::get_addr() const { return addr_; }
+
+bool HttpDownstreamConnection::poolable() const {
+  return !group_->retired && reusable_;
+}
+
+const Address *HttpDownstreamConnection::get_raddr() const { return raddr_; }
+
+} // namespace shrpx