Adding upstream version 1.59.0.upstream/1.59.0

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

1 files changed, 844 insertions, 0 deletions

diff --git a/src/h2load_quic.cc b/src/h2load_quic.cc
new file mode 100644
index 0000000..e492a3e
--- /dev/null
+++ b/src/h2load_quic.cc
@@ -0,0 +1,844 @@
+/*
+ * nghttp2 - HTTP/2 C Library
+ *
+ * Copyright (c) 2019 nghttp2 contributors
+ *
+ * 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 "h2load_quic.h"
+
+#include <netinet/udp.h>
+
+#include <iostream>
+
+#ifdef HAVE_LIBNGTCP2_CRYPTO_QUICTLS
+#  include <ngtcp2/ngtcp2_crypto_quictls.h>
+#endif // HAVE_LIBNGTCP2_CRYPTO_QUICTLS
+#ifdef HAVE_LIBNGTCP2_CRYPTO_BORINGSSL
+#  include <ngtcp2/ngtcp2_crypto_boringssl.h>
+#endif // HAVE_LIBNGTCP2_CRYPTO_BORINGSSL
+
+#include <openssl/err.h>
+#include <openssl/rand.h>
+
+#include "h2load_http3_session.h"
+
+namespace h2load {
+
+namespace {
+int handshake_completed(ngtcp2_conn *conn, void *user_data) {
+  auto c = static_cast<Client *>(user_data);
+
+  if (c->quic_handshake_completed() != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+
+  return 0;
+}
+} // namespace
+
+int Client::quic_handshake_completed() { return connection_made(); }
+
+namespace {
+int recv_stream_data(ngtcp2_conn *conn, uint32_t flags, int64_t stream_id,
+                     uint64_t offset, const uint8_t *data, size_t datalen,
+                     void *user_data, void *stream_user_data) {
+  auto c = static_cast<Client *>(user_data);
+  if (c->quic_recv_stream_data(flags, stream_id, data, datalen) != 0) {
+    // TODO Better to do this gracefully rather than
+    // NGTCP2_ERR_CALLBACK_FAILURE.  Perhaps, call
+    // ngtcp2_conn_write_application_close() ?
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+  return 0;
+}
+} // namespace
+
+int Client::quic_recv_stream_data(uint32_t flags, int64_t stream_id,
+                                  const uint8_t *data, size_t datalen) {
+  if (worker->current_phase == Phase::MAIN_DURATION) {
+    worker->stats.bytes_total += datalen;
+  }
+
+  auto s = static_cast<Http3Session *>(session.get());
+  auto nconsumed = s->read_stream(flags, stream_id, data, datalen);
+  if (nconsumed == -1) {
+    return -1;
+  }
+
+  ngtcp2_conn_extend_max_stream_offset(quic.conn, stream_id, nconsumed);
+  ngtcp2_conn_extend_max_offset(quic.conn, nconsumed);
+
+  return 0;
+}
+
+namespace {
+int acked_stream_data_offset(ngtcp2_conn *conn, int64_t stream_id,
+                             uint64_t offset, uint64_t datalen, void *user_data,
+                             void *stream_user_data) {
+  auto c = static_cast<Client *>(user_data);
+  if (c->quic_acked_stream_data_offset(stream_id, datalen) != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+  return 0;
+}
+} // namespace
+
+int Client::quic_acked_stream_data_offset(int64_t stream_id, size_t datalen) {
+  auto s = static_cast<Http3Session *>(session.get());
+  if (s->add_ack_offset(stream_id, datalen) != 0) {
+    return -1;
+  }
+  return 0;
+}
+
+namespace {
+int stream_close(ngtcp2_conn *conn, uint32_t flags, int64_t stream_id,
+                 uint64_t app_error_code, void *user_data,
+                 void *stream_user_data) {
+  auto c = static_cast<Client *>(user_data);
+
+  if (!(flags & NGTCP2_STREAM_CLOSE_FLAG_APP_ERROR_CODE_SET)) {
+    app_error_code = NGHTTP3_H3_NO_ERROR;
+  }
+
+  if (c->quic_stream_close(stream_id, app_error_code) != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+  return 0;
+}
+} // namespace
+
+int Client::quic_stream_close(int64_t stream_id, uint64_t app_error_code) {
+  auto s = static_cast<Http3Session *>(session.get());
+  if (s->close_stream(stream_id, app_error_code) != 0) {
+    return -1;
+  }
+  return 0;
+}
+
+namespace {
+int stream_reset(ngtcp2_conn *conn, int64_t stream_id, uint64_t final_size,
+                 uint64_t app_error_code, void *user_data,
+                 void *stream_user_data) {
+  auto c = static_cast<Client *>(user_data);
+  if (c->quic_stream_reset(stream_id, app_error_code) != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+  return 0;
+}
+} // namespace
+
+int Client::quic_stream_reset(int64_t stream_id, uint64_t app_error_code) {
+  auto s = static_cast<Http3Session *>(session.get());
+  if (s->shutdown_stream_read(stream_id) != 0) {
+    return -1;
+  }
+  return 0;
+}
+
+namespace {
+int stream_stop_sending(ngtcp2_conn *conn, int64_t stream_id,
+                        uint64_t app_error_code, void *user_data,
+                        void *stream_user_data) {
+  auto c = static_cast<Client *>(user_data);
+  if (c->quic_stream_stop_sending(stream_id, app_error_code) != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+  return 0;
+}
+} // namespace
+
+int Client::quic_stream_stop_sending(int64_t stream_id,
+                                     uint64_t app_error_code) {
+  auto s = static_cast<Http3Session *>(session.get());
+  if (s->shutdown_stream_read(stream_id) != 0) {
+    return -1;
+  }
+  return 0;
+}
+
+namespace {
+int extend_max_local_streams_bidi(ngtcp2_conn *conn, uint64_t max_streams,
+                                  void *user_data) {
+  auto c = static_cast<Client *>(user_data);
+
+  if (c->quic_extend_max_local_streams() != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+
+  return 0;
+}
+} // namespace
+
+int Client::quic_extend_max_local_streams() {
+  auto s = static_cast<Http3Session *>(session.get());
+  if (s->extend_max_local_streams() != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+  return 0;
+}
+
+namespace {
+int extend_max_stream_data(ngtcp2_conn *conn, int64_t stream_id,
+                           uint64_t max_data, void *user_data,
+                           void *stream_user_data) {
+  auto c = static_cast<Client *>(user_data);
+
+  if (c->quic_extend_max_stream_data(stream_id) != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+
+  return 0;
+}
+} // namespace
+
+int Client::quic_extend_max_stream_data(int64_t stream_id) {
+  auto s = static_cast<Http3Session *>(session.get());
+  if (s->unblock_stream(stream_id) != 0) {
+    return -1;
+  }
+  return 0;
+}
+
+namespace {
+int get_new_connection_id(ngtcp2_conn *conn, ngtcp2_cid *cid, uint8_t *token,
+                          size_t cidlen, void *user_data) {
+  if (RAND_bytes(cid->data, cidlen) != 1) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+
+  cid->datalen = cidlen;
+
+  if (RAND_bytes(token, NGTCP2_STATELESS_RESET_TOKENLEN) != 1) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+
+  return 0;
+}
+} // namespace
+
+namespace {
+void debug_log_printf(void *user_data, const char *fmt, ...) {
+  va_list ap;
+
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+
+  fprintf(stderr, "\n");
+}
+} // namespace
+
+namespace {
+int generate_cid(ngtcp2_cid &dest) {
+  dest.datalen = 8;
+
+  if (RAND_bytes(dest.data, dest.datalen) != 1) {
+    return -1;
+  }
+
+  return 0;
+}
+} // namespace
+
+namespace {
+ngtcp2_tstamp quic_timestamp() {
+  return std::chrono::duration_cast<std::chrono::nanoseconds>(
+             std::chrono::steady_clock::now().time_since_epoch())
+      .count();
+}
+} // namespace
+
+// qlog write callback -- excerpted from ngtcp2/examples/client_base.cc
+namespace {
+void qlog_write_cb(void *user_data, uint32_t flags, const void *data,
+                   size_t datalen) {
+  auto c = static_cast<Client *>(user_data);
+  c->quic_write_qlog(data, datalen);
+}
+} // namespace
+
+void Client::quic_write_qlog(const void *data, size_t datalen) {
+  assert(quic.qlog_file != nullptr);
+  fwrite(data, 1, datalen, quic.qlog_file);
+}
+
+namespace {
+void rand(uint8_t *dest, size_t destlen, const ngtcp2_rand_ctx *rand_ctx) {
+  util::random_bytes(dest, dest + destlen,
+                     *static_cast<std::mt19937 *>(rand_ctx->native_handle));
+}
+} // namespace
+
+namespace {
+int recv_rx_key(ngtcp2_conn *conn, ngtcp2_encryption_level level,
+                void *user_data) {
+  if (level != NGTCP2_ENCRYPTION_LEVEL_1RTT) {
+    return 0;
+  }
+
+  auto c = static_cast<Client *>(user_data);
+
+  if (c->quic_make_http3_session() != 0) {
+    return NGTCP2_ERR_CALLBACK_FAILURE;
+  }
+
+  return 0;
+}
+} // namespace
+
+int Client::quic_make_http3_session() {
+  auto s = std::make_unique<Http3Session>(this);
+  if (s->init_conn() == -1) {
+    return -1;
+  }
+  session = std::move(s);
+
+  return 0;
+}
+
+namespace {
+ngtcp2_conn *get_conn(ngtcp2_crypto_conn_ref *conn_ref) {
+  auto c = static_cast<Client *>(conn_ref->user_data);
+  return c->quic.conn;
+}
+} // namespace
+
+int Client::quic_init(const sockaddr *local_addr, socklen_t local_addrlen,
+                      const sockaddr *remote_addr, socklen_t remote_addrlen) {
+  int rv;
+
+  if (!ssl) {
+    ssl = SSL_new(worker->ssl_ctx);
+
+    quic.conn_ref.get_conn = get_conn;
+    quic.conn_ref.user_data = this;
+
+    SSL_set_app_data(ssl, &quic.conn_ref);
+    SSL_set_connect_state(ssl);
+    SSL_set_quic_use_legacy_codepoint(ssl, 0);
+  }
+
+  auto callbacks = ngtcp2_callbacks{
+      ngtcp2_crypto_client_initial_cb,
+      nullptr, // recv_client_initial
+      ngtcp2_crypto_recv_crypto_data_cb,
+      h2load::handshake_completed,
+      nullptr, // recv_version_negotiation
+      ngtcp2_crypto_encrypt_cb,
+      ngtcp2_crypto_decrypt_cb,
+      ngtcp2_crypto_hp_mask_cb,
+      h2load::recv_stream_data,
+      h2load::acked_stream_data_offset,
+      nullptr, // stream_open
+      h2load::stream_close,
+      nullptr, // recv_stateless_reset
+      ngtcp2_crypto_recv_retry_cb,
+      h2load::extend_max_local_streams_bidi,
+      nullptr, // extend_max_local_streams_uni
+      h2load::rand,
+      get_new_connection_id,
+      nullptr, // remove_connection_id
+      ngtcp2_crypto_update_key_cb,
+      nullptr, // path_validation
+      nullptr, // select_preferred_addr
+      h2load::stream_reset,
+      nullptr, // extend_max_remote_streams_bidi
+      nullptr, // extend_max_remote_streams_uni
+      h2load::extend_max_stream_data,
+      nullptr, // dcid_status
+      nullptr, // handshake_confirmed
+      nullptr, // recv_new_token
+      ngtcp2_crypto_delete_crypto_aead_ctx_cb,
+      ngtcp2_crypto_delete_crypto_cipher_ctx_cb,
+      nullptr, // recv_datagram
+      nullptr, // ack_datagram
+      nullptr, // lost_datagram
+      ngtcp2_crypto_get_path_challenge_data_cb,
+      h2load::stream_stop_sending,
+      nullptr, // version_negotiation
+      h2load::recv_rx_key,
+      nullptr, // recv_tx_key
+  };
+
+  ngtcp2_cid scid, dcid;
+  if (generate_cid(scid) != 0) {
+    return -1;
+  }
+  if (generate_cid(dcid) != 0) {
+    return -1;
+  }
+
+  auto config = worker->config;
+
+  ngtcp2_settings settings;
+  ngtcp2_settings_default(&settings);
+  if (config->verbose) {
+    settings.log_printf = debug_log_printf;
+  }
+  settings.initial_ts = quic_timestamp();
+  settings.rand_ctx.native_handle = &worker->randgen;
+  if (!config->qlog_file_base.empty()) {
+    assert(quic.qlog_file == nullptr);
+    auto path = config->qlog_file_base;
+    path += '.';
+    path += util::utos(worker->id);
+    path += '.';
+    path += util::utos(id);
+    path += ".sqlog";
+    quic.qlog_file = fopen(path.c_str(), "w");
+    if (quic.qlog_file == nullptr) {
+      std::cerr << "Failed to open a qlog file: " << path << std::endl;
+      return -1;
+    }
+    settings.qlog_write = qlog_write_cb;
+  }
+  if (config->max_udp_payload_size) {
+    settings.max_tx_udp_payload_size = config->max_udp_payload_size;
+    settings.no_tx_udp_payload_size_shaping = 1;
+  }
+
+  ngtcp2_transport_params params;
+  ngtcp2_transport_params_default(&params);
+  auto max_stream_data =
+      std::min((1 << 26) - 1, (1 << config->window_bits) - 1);
+  params.initial_max_stream_data_bidi_local = max_stream_data;
+  params.initial_max_stream_data_uni = max_stream_data;
+  params.initial_max_data = (1 << config->connection_window_bits) - 1;
+  params.initial_max_streams_bidi = 0;
+  params.initial_max_streams_uni = 100;
+  params.max_idle_timeout = 30 * NGTCP2_SECONDS;
+
+  auto path = ngtcp2_path{
+      {
+          const_cast<sockaddr *>(local_addr),
+          local_addrlen,
+      },
+      {
+          const_cast<sockaddr *>(remote_addr),
+          remote_addrlen,
+      },
+  };
+
+  assert(config->alpn_list.size());
+
+  uint32_t quic_version;
+
+  if (config->alpn_list[0] == NGHTTP3_ALPN_H3) {
+    quic_version = NGTCP2_PROTO_VER_V1;
+  } else {
+    quic_version = NGTCP2_PROTO_VER_MIN;
+  }
+
+  rv = ngtcp2_conn_client_new(&quic.conn, &dcid, &scid, &path, quic_version,
+                              &callbacks, &settings, &params, nullptr, this);
+  if (rv != 0) {
+    return -1;
+  }
+
+  ngtcp2_conn_set_tls_native_handle(quic.conn, ssl);
+
+  return 0;
+}
+
+void Client::quic_free() {
+  ngtcp2_conn_del(quic.conn);
+  if (quic.qlog_file != nullptr) {
+    fclose(quic.qlog_file);
+    quic.qlog_file = nullptr;
+  }
+}
+
+void Client::quic_close_connection() {
+  if (!quic.conn) {
+    return;
+  }
+
+  std::array<uint8_t, NGTCP2_MAX_UDP_PAYLOAD_SIZE> buf;
+  ngtcp2_path_storage ps;
+  ngtcp2_path_storage_zero(&ps);
+
+  auto nwrite = ngtcp2_conn_write_connection_close(
+      quic.conn, &ps.path, nullptr, buf.data(), buf.size(), &quic.last_error,
+      quic_timestamp());
+
+  if (nwrite <= 0) {
+    return;
+  }
+
+  write_udp(reinterpret_cast<sockaddr *>(ps.path.remote.addr),
+            ps.path.remote.addrlen, buf.data(), nwrite, 0);
+}
+
+int Client::quic_write_client_handshake(ngtcp2_encryption_level level,
+                                        const uint8_t *data, size_t datalen) {
+  int rv;
+
+  assert(level < 2);
+
+  rv = ngtcp2_conn_submit_crypto_data(quic.conn, level, data, datalen);
+  if (rv != 0) {
+    std::cerr << "ngtcp2_conn_submit_crypto_data: " << ngtcp2_strerror(rv)
+              << std::endl;
+    return -1;
+  }
+
+  return 0;
+}
+
+void quic_pkt_timeout_cb(struct ev_loop *loop, ev_timer *w, int revents) {
+  auto c = static_cast<Client *>(w->data);
+
+  if (c->quic_pkt_timeout() != 0) {
+    c->fail();
+    c->worker->free_client(c);
+    delete c;
+    return;
+  }
+}
+
+int Client::quic_pkt_timeout() {
+  int rv;
+  auto now = quic_timestamp();
+
+  rv = ngtcp2_conn_handle_expiry(quic.conn, now);
+  if (rv != 0) {
+    ngtcp2_ccerr_set_liberr(&quic.last_error, rv, nullptr, 0);
+    return -1;
+  }
+
+  return write_quic();
+}
+
+void Client::quic_restart_pkt_timer() {
+  auto expiry = ngtcp2_conn_get_expiry(quic.conn);
+  auto now = quic_timestamp();
+  auto t = expiry > now ? static_cast<ev_tstamp>(expiry - now) / NGTCP2_SECONDS
+                        : 1e-9;
+  quic.pkt_timer.repeat = t;
+  ev_timer_again(worker->loop, &quic.pkt_timer);
+}
+
+int Client::read_quic() {
+  std::array<uint8_t, 65535> buf;
+  sockaddr_union su;
+  int rv;
+  size_t pktcnt = 0;
+  ngtcp2_pkt_info pi{};
+
+  iovec msg_iov;
+  msg_iov.iov_base = buf.data();
+  msg_iov.iov_len = buf.size();
+
+  msghdr msg{};
+  msg.msg_name = &su;
+  msg.msg_iov = &msg_iov;
+  msg.msg_iovlen = 1;
+
+  uint8_t msg_ctrl[CMSG_SPACE(sizeof(uint16_t))];
+  msg.msg_control = msg_ctrl;
+
+  auto ts = quic_timestamp();
+
+  for (;;) {
+    msg.msg_namelen = sizeof(su);
+    msg.msg_controllen = sizeof(msg_ctrl);
+
+    auto nread = recvmsg(fd, &msg, 0);
+    if (nread == -1) {
+      return 0;
+    }
+
+    auto gso_size = util::msghdr_get_udp_gro(&msg);
+    if (gso_size == 0) {
+      gso_size = static_cast<size_t>(nread);
+    }
+
+    assert(quic.conn);
+
+    ++worker->stats.udp_dgram_recv;
+
+    auto path = ngtcp2_path{
+        {
+            &local_addr.su.sa,
+            static_cast<socklen_t>(local_addr.len),
+        },
+        {
+            &su.sa,
+            msg.msg_namelen,
+        },
+    };
+
+    auto data = buf.data();
+
+    for (;;) {
+      auto datalen = std::min(static_cast<size_t>(nread), gso_size);
+
+      ++pktcnt;
+
+      rv = ngtcp2_conn_read_pkt(quic.conn, &path, &pi, data, datalen, ts);
+      if (rv != 0) {
+        if (!quic.last_error.error_code) {
+          if (rv == NGTCP2_ERR_CRYPTO) {
+            ngtcp2_ccerr_set_tls_alert(&quic.last_error,
+                                       ngtcp2_conn_get_tls_alert(quic.conn),
+                                       nullptr, 0);
+          } else {
+            ngtcp2_ccerr_set_liberr(&quic.last_error, rv, nullptr, 0);
+          }
+        }
+
+        return -1;
+      }
+
+      nread -= datalen;
+      if (nread == 0) {
+        break;
+      }
+
+      data += datalen;
+    }
+
+    if (pktcnt >= 100) {
+      break;
+    }
+  }
+
+  return 0;
+}
+
+int Client::write_quic() {
+  int rv;
+
+  ev_io_stop(worker->loop, &wev);
+
+  if (quic.close_requested) {
+    return -1;
+  }
+
+  if (quic.tx.send_blocked) {
+    rv = send_blocked_packet();
+    if (rv != 0) {
+      return -1;
+    }
+
+    if (quic.tx.send_blocked) {
+      return 0;
+    }
+  }
+
+  std::array<nghttp3_vec, 16> vec;
+  size_t pktcnt = 0;
+  auto max_udp_payload_size =
+      ngtcp2_conn_get_max_tx_udp_payload_size(quic.conn);
+#ifdef UDP_SEGMENT
+  auto path_max_udp_payload_size =
+      ngtcp2_conn_get_path_max_tx_udp_payload_size(quic.conn);
+#endif // UDP_SEGMENT
+  auto max_pktcnt =
+      ngtcp2_conn_get_send_quantum(quic.conn) / max_udp_payload_size;
+  uint8_t *bufpos = quic.tx.data.get();
+  ngtcp2_path_storage ps;
+  size_t gso_size = 0;
+
+  ngtcp2_path_storage_zero(&ps);
+
+  auto s = static_cast<Http3Session *>(session.get());
+  auto ts = quic_timestamp();
+
+  for (;;) {
+    int64_t stream_id = -1;
+    int fin = 0;
+    ssize_t sveccnt = 0;
+
+    if (session && ngtcp2_conn_get_max_data_left(quic.conn)) {
+      sveccnt = s->write_stream(stream_id, fin, vec.data(), vec.size());
+      if (sveccnt == -1) {
+        return -1;
+      }
+    }
+
+    ngtcp2_ssize ndatalen;
+    auto v = vec.data();
+    auto vcnt = static_cast<size_t>(sveccnt);
+
+    uint32_t flags = NGTCP2_WRITE_STREAM_FLAG_MORE;
+    if (fin) {
+      flags |= NGTCP2_WRITE_STREAM_FLAG_FIN;
+    }
+
+    auto nwrite = ngtcp2_conn_writev_stream(
+        quic.conn, &ps.path, nullptr, bufpos, max_udp_payload_size, &ndatalen,
+        flags, stream_id, reinterpret_cast<const ngtcp2_vec *>(v), vcnt, ts);
+    if (nwrite < 0) {
+      switch (nwrite) {
+      case NGTCP2_ERR_STREAM_DATA_BLOCKED:
+        assert(ndatalen == -1);
+        s->block_stream(stream_id);
+        continue;
+      case NGTCP2_ERR_STREAM_SHUT_WR:
+        assert(ndatalen == -1);
+        s->shutdown_stream_write(stream_id);
+        continue;
+      case NGTCP2_ERR_WRITE_MORE:
+        assert(ndatalen >= 0);
+        if (s->add_write_offset(stream_id, ndatalen) != 0) {
+          return -1;
+        }
+        continue;
+      }
+
+      ngtcp2_ccerr_set_liberr(&quic.last_error, nwrite, nullptr, 0);
+      return -1;
+    } else if (ndatalen >= 0 && s->add_write_offset(stream_id, ndatalen) != 0) {
+      return -1;
+    }
+
+    quic_restart_pkt_timer();
+
+    if (nwrite == 0) {
+      if (bufpos - quic.tx.data.get()) {
+        auto data = quic.tx.data.get();
+        auto datalen = bufpos - quic.tx.data.get();
+        rv = write_udp(ps.path.remote.addr, ps.path.remote.addrlen, data,
+                       datalen, gso_size);
+        if (rv == 1) {
+          on_send_blocked(ps.path.remote, data, datalen, gso_size);
+          signal_write();
+          return 0;
+        }
+      }
+      return 0;
+    }
+
+    bufpos += nwrite;
+
+#ifdef UDP_SEGMENT
+    if (worker->config->no_udp_gso) {
+#endif // UDP_SEGMENT
+      auto data = quic.tx.data.get();
+      auto datalen = bufpos - quic.tx.data.get();
+      rv = write_udp(ps.path.remote.addr, ps.path.remote.addrlen, data, datalen,
+                     0);
+      if (rv == 1) {
+        on_send_blocked(ps.path.remote, data, datalen, 0);
+        signal_write();
+        return 0;
+      }
+
+      if (++pktcnt == max_pktcnt) {
+        signal_write();
+        return 0;
+      }
+
+      bufpos = quic.tx.data.get();
+
+#ifdef UDP_SEGMENT
+      continue;
+    }
+#endif // UDP_SEGMENT
+
+#ifdef UDP_SEGMENT
+    if (pktcnt == 0) {
+      gso_size = nwrite;
+    } else if (static_cast<size_t>(nwrite) > gso_size ||
+               (gso_size > path_max_udp_payload_size &&
+                static_cast<size_t>(nwrite) != gso_size)) {
+      auto data = quic.tx.data.get();
+      auto datalen = bufpos - quic.tx.data.get() - nwrite;
+      rv = write_udp(ps.path.remote.addr, ps.path.remote.addrlen, data, datalen,
+                     gso_size);
+      if (rv == 1) {
+        on_send_blocked(ps.path.remote, data, datalen, gso_size);
+        on_send_blocked(ps.path.remote, bufpos - nwrite, nwrite, 0);
+      } else {
+        auto data = bufpos - nwrite;
+        rv = write_udp(ps.path.remote.addr, ps.path.remote.addrlen, data,
+                       nwrite, 0);
+        if (rv == 1) {
+          on_send_blocked(ps.path.remote, data, nwrite, 0);
+        }
+      }
+
+      signal_write();
+      return 0;
+    }
+
+    // Assume that the path does not change.
+    if (++pktcnt == max_pktcnt || static_cast<size_t>(nwrite) < gso_size) {
+      auto data = quic.tx.data.get();
+      auto datalen = bufpos - quic.tx.data.get();
+      rv = write_udp(ps.path.remote.addr, ps.path.remote.addrlen, data, datalen,
+                     gso_size);
+      if (rv == 1) {
+        on_send_blocked(ps.path.remote, data, datalen, gso_size);
+      }
+      signal_write();
+      return 0;
+    }
+#endif // UDP_SEGMENT
+  }
+}
+
+void Client::on_send_blocked(const ngtcp2_addr &remote_addr,
+                             const uint8_t *data, size_t datalen,
+                             size_t gso_size) {
+  assert(quic.tx.num_blocked || !quic.tx.send_blocked);
+  assert(quic.tx.num_blocked < 2);
+
+  quic.tx.send_blocked = true;
+
+  auto &p = quic.tx.blocked[quic.tx.num_blocked++];
+
+  memcpy(&p.remote_addr.su, remote_addr.addr, remote_addr.addrlen);
+
+  p.remote_addr.len = remote_addr.addrlen;
+  p.data = data;
+  p.datalen = datalen;
+  p.gso_size = gso_size;
+}
+
+int Client::send_blocked_packet() {
+  int rv;
+
+  assert(quic.tx.send_blocked);
+
+  for (; quic.tx.num_blocked_sent < quic.tx.num_blocked;
+       ++quic.tx.num_blocked_sent) {
+    auto &p = quic.tx.blocked[quic.tx.num_blocked_sent];
+
+    rv = write_udp(&p.remote_addr.su.sa, p.remote_addr.len, p.data, p.datalen,
+                   p.gso_size);
+    if (rv == 1) {
+      signal_write();
+
+      return 0;
+    }
+  }
+
+  quic.tx.send_blocked = false;
+  quic.tx.num_blocked = 0;
+  quic.tx.num_blocked_sent = 0;
+
+  return 0;
+}
+
+} // namespace h2load