git.sesse.net Git - cubemap/blob - server.cpp

   1 #include <assert.h>
   2 #include <errno.h>
   3 #include <inttypes.h>
   4 #include <limits.h>
   5 #include <netinet/in.h>
   6 #include <netinet/tcp.h>
   7 #include <pthread.h>
   8 #include <stdint.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <sys/epoll.h>
  13 #include <sys/sendfile.h>
  14 #include <sys/socket.h>
  15 #include <sys/types.h>
  16 #include <unistd.h>
  17 #include <algorithm>
  18 #include <map>
  19 #include <string>
  20 #include <utility>
  21 #include <vector>
  22
  23 #include "ktls.h"
  24 #include "tlse.h"
  25
  26 #include "acceptor.h"
  27 #include "accesslog.h"
  28 #include "log.h"
  29 #include "metacube2.h"
  30 #include "parse.h"
  31 #include "server.h"
  32 #include "state.pb.h"
  33 #include "stream.h"
  34 #include "util.h"
  35
  36 #ifndef SO_MAX_PACING_RATE
  37 #define SO_MAX_PACING_RATE 47
  38 #endif
  39
  40 using namespace std;
  41
  42 extern AccessLogThread *access_log;
  43
  44 namespace {
  45
  46 inline bool is_equal(timespec a, timespec b)
  47 {
  48         return a.tv_sec == b.tv_sec &&
  49                a.tv_nsec == b.tv_nsec;
  50 }
  51
  52 inline bool is_earlier(timespec a, timespec b)
  53 {
  54         if (a.tv_sec != b.tv_sec)
  55                 return a.tv_sec < b.tv_sec;
  56         return a.tv_nsec < b.tv_nsec;
  57 }
  58
  59 }  // namespace
  60
  61 Server::Server()
  62 {
  63         epoll_fd = epoll_create(1024);  // Size argument is ignored.
  64         if (epoll_fd == -1) {
  65                 log_perror("epoll_fd");
  66                 exit(1);
  67         }
  68 }
  69
  70 Server::~Server()
  71 {
  72         safe_close(epoll_fd);
  73 }
  74
  75 vector<ClientStats> Server::get_client_stats() const
  76 {
  77         vector<ClientStats> ret;
  78
  79         lock_guard<mutex> lock(mu);
  80         for (const auto &fd_and_client : clients) {
  81                 ret.push_back(fd_and_client.second.get_stats());
  82         }
  83         return ret;
  84 }
  85
  86 vector<HLSZombie> Server::get_hls_zombies()
  87 {
  88         vector<HLSZombie> ret;
  89
  90         timespec now;
  91         if (clock_gettime(CLOCK_MONOTONIC_COARSE, &now) == -1) {
  92                 log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
  93                 return ret;
  94         }
  95
  96         lock_guard<mutex> lock(mu);
  97         for (auto it = hls_zombies.begin(); it != hls_zombies.end(); ) {
  98                 if (is_earlier(it->second.expires, now)) {
  99                         hls_zombies.erase(it++);
 100                 } else {
 101                         ret.push_back(it->second);
 102                         ++it;
 103                 }
 104         }
 105         return ret;
 106 }
 107
 108 void Server::do_work()
 109 {
 110         while (!should_stop()) {
 111                 // Wait until there's activity on at least one of the fds,
 112                 // or 20 ms (about one frame at 50 fps) has elapsed.
 113                 //
 114                 // We could in theory wait forever and rely on wakeup()
 115                 // from add_client_deferred() and add_data_deferred(),
 116                 // but wakeup is a pretty expensive operation, and the
 117                 // two threads might end up fighting over a lock, so it's
 118                 // seemingly (much) more efficient to just have a timeout here.
 119                 int nfds = epoll_pwait(epoll_fd, events, EPOLL_MAX_EVENTS, EPOLL_TIMEOUT_MS, &sigset_without_usr1_block);
 120                 if (nfds == -1 && errno != EINTR) {
 121                         log_perror("epoll_wait");
 122                         exit(1);
 123                 }
 124
 125                 lock_guard<mutex> lock(mu);  // We release the mutex between iterations.
 126
 127                 process_queued_data();
 128
 129                 // Process each client where we have socket activity.
 130                 for (int i = 0; i < nfds; ++i) {
 131                         Client *client = reinterpret_cast<Client *>(events[i].data.ptr);
 132
 133                         if (events[i].events & (EPOLLERR | EPOLLRDHUP | EPOLLHUP)) {
 134                                 close_client(client);
 135                                 continue;
 136                         }
 137
 138                         process_client(client);
 139                 }
 140
 141                 // Process each client where its stream has new data,
 142                 // even if there was no socket activity.
 143                 for (unique_ptr<Stream> &stream : streams) {
 144                         vector<Client *> to_process;
 145                         swap(stream->to_process, to_process);
 146                         for (Client *client : to_process) {
 147                                 process_client(client);
 148                         }
 149                 }
 150
 151                 // Finally, go through each client to see if it's timed out
 152                 // in the READING_REQUEST state. (Seemingly there are clients
 153                 // that can hold sockets up for days at a time without sending
 154                 // anything at all.)
 155                 timespec timeout_time;
 156                 if (clock_gettime(CLOCK_MONOTONIC_COARSE, &timeout_time) == -1) {
 157                         log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
 158                         continue;
 159                 }
 160                 timeout_time.tv_sec -= REQUEST_READ_TIMEOUT_SEC;
 161                 while (!clients_ordered_by_connect_time.empty()) {
 162                         const pair<timespec, int> &connect_time_and_fd = clients_ordered_by_connect_time.front();
 163
 164                         // See if we have reached the end of clients to process.
 165                         if (is_earlier(timeout_time, connect_time_and_fd.first)) {
 166                                 break;
 167                         }
 168
 169                         // If this client doesn't exist anymore, just ignore it
 170                         // (it was deleted earlier).
 171                         auto client_it = clients.find(connect_time_and_fd.second);
 172                         if (client_it == clients.end()) {
 173                                 clients_ordered_by_connect_time.pop();
 174                                 continue;
 175                         }
 176                         Client *client = &client_it->second;
 177                         if (!is_equal(client->connect_time, connect_time_and_fd.first)) {
 178                                 // Another client has taken this fd in the meantime.
 179                                 clients_ordered_by_connect_time.pop();
 180                                 continue;
 181                         }
 182
 183                         if (client->state != Client::READING_REQUEST) {
 184                                 // Only READING_REQUEST can time out.
 185                                 clients_ordered_by_connect_time.pop();
 186                                 continue;
 187                         }
 188
 189                         // OK, it timed out.
 190                         close_client(client);
 191                         clients_ordered_by_connect_time.pop();
 192                 }
 193         }
 194 }
 195
 196 CubemapStateProto Server::serialize(unordered_map<const string *, size_t> *short_response_pool)
 197 {
 198         // We don't serialize anything queued, so empty the queues.
 199         process_queued_data();
 200
 201         // Set all clients in a consistent state before serializing
 202         // (ie., they have no remaining lost data). Otherwise, increasing
 203         // the backlog could take clients into a newly valid area of the backlog,
 204         // sending a stream of zeros instead of skipping the data as it should.
 205         //
 206         // TODO: Do this when clients are added back from serialized state instead;
 207         // it would probably be less wasteful.
 208         for (auto &fd_and_client : clients) {
 209                 skip_lost_data(&fd_and_client.second);
 210         }
 211
 212         CubemapStateProto serialized;
 213         for (const auto &fd_and_client : clients) {
 214                 serialized.add_clients()->MergeFrom(fd_and_client.second.serialize(short_response_pool));
 215         }
 216         for (unique_ptr<Stream> &stream : streams) {
 217                 serialized.add_streams()->MergeFrom(stream->serialize());
 218         }
 219         for (const auto &key_and_zombie : hls_zombies) {
 220                 HLSZombieProto *proto = serialized.add_hls_zombies();
 221                 proto->set_key(key_and_zombie.first);
 222
 223                 const HLSZombie &zombie = key_and_zombie.second;
 224                 proto->set_remote_addr(zombie.remote_addr);
 225                 proto->set_url(zombie.url);
 226                 proto->set_referer(zombie.referer);
 227                 proto->set_user_agent(zombie.user_agent);
 228                 proto->set_expires_sec(zombie.expires.tv_sec);
 229                 proto->set_expires_nsec(zombie.expires.tv_nsec);
 230         }
 231         return serialized;
 232 }
 233
 234 void Server::add_client_deferred(int sock, Acceptor *acceptor)
 235 {
 236         lock_guard<mutex> lock(queued_clients_mutex);
 237         queued_add_clients.push_back(std::make_pair(sock, acceptor));
 238 }
 239
 240 void Server::add_client(int sock, Acceptor *acceptor)
 241 {
 242         const bool is_tls = acceptor->is_tls();
 243         auto inserted = clients.insert(make_pair(sock, Client(sock)));
 244         assert(inserted.second == true);  // Should not already exist.
 245         Client *client_ptr = &inserted.first->second;
 246
 247         start_client_timeout_timer(client_ptr);
 248
 249         // Start listening on data from this socket.
 250         epoll_event ev;
 251         if (is_tls) {
 252                 // Even in the initial state (READING_REQUEST), TLS needs to
 253                 // send data for the handshake, and thus might end up needing
 254                 // to know about EPOLLOUT.
 255                 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLRDHUP;
 256         } else {
 257                 // EPOLLOUT will be added once we go out of READING_REQUEST.
 258                 ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
 259         }
 260         ev.data.ptr = client_ptr;
 261         if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sock, &ev) == -1) {
 262                 log_perror("epoll_ctl(EPOLL_CTL_ADD)");
 263                 exit(1);
 264         }
 265
 266         if (is_tls) {
 267                 assert(tls_server_contexts.count(acceptor));
 268                 client_ptr->tls_context = tls_accept(tls_server_contexts[acceptor]);
 269                 if (client_ptr->tls_context == nullptr) {
 270                         log(ERROR, "tls_accept() failed");
 271                         close_client(client_ptr);
 272                         return;
 273                 }
 274                 tls_make_exportable(client_ptr->tls_context, 1);
 275         }
 276
 277         process_client(client_ptr);
 278 }
 279
 280 void Server::add_client_from_serialized(const ClientProto &client, const vector<shared_ptr<const string>> &short_responses)
 281 {
 282         lock_guard<mutex> lock(mu);
 283         Stream *stream;
 284         int stream_index = lookup_stream_by_url(client.url());
 285         if (stream_index == -1) {
 286                 assert(client.state() != Client::SENDING_DATA);
 287                 stream = nullptr;
 288         } else {
 289                 stream = streams[stream_index].get();
 290         }
 291         auto inserted = clients.insert(make_pair(client.sock(), Client(client, short_responses, stream)));
 292         assert(inserted.second == true);  // Should not already exist.
 293         Client *client_ptr = &inserted.first->second;
 294
 295         // Connection timestamps must be nondecreasing.
 296         assert(clients_ordered_by_connect_time.empty() ||
 297                !is_earlier(client_ptr->connect_time, clients_ordered_by_connect_time.back().first));
 298         clients_ordered_by_connect_time.push(make_pair(client_ptr->connect_time, client.sock()));
 299
 300         // Start listening on data from this socket.
 301         epoll_event ev;
 302         if (client.state() == Client::READING_REQUEST) {
 303                 // See the corresponding comment in Server::add_client().
 304                 if (client.has_tls_context()) {
 305                         ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLRDHUP;
 306                 } else {
 307                         ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
 308                 }
 309         } else {
 310                 // If we don't have more data for this client, we'll be putting it into
 311                 // the sleeping array again soon.
 312                 ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
 313         }
 314         ev.data.ptr = client_ptr;
 315         if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client.sock(), &ev) == -1) {
 316                 log_perror("epoll_ctl(EPOLL_CTL_ADD)");
 317                 exit(1);
 318         }
 319
 320         if (client_ptr->state == Client::WAITING_FOR_KEYFRAME ||
 321             client_ptr->state == Client::PREBUFFERING ||
 322             (client_ptr->state == Client::SENDING_DATA &&
 323              client_ptr->stream_pos == client_ptr->stream->bytes_received)) {
 324                 client_ptr->stream->put_client_to_sleep(client_ptr);
 325         } else {
 326                 process_client(client_ptr);
 327         }
 328 }
 329
 330 void Server::start_client_timeout_timer(Client *client)
 331 {
 332         // Connection timestamps must be nondecreasing. I can't find any guarantee
 333         // that even the monotonic clock can't go backwards by a small amount
 334         // (think switching between CPUs with non-synchronized TSCs), so if
 335         // this actually should happen, we hack around it by fudging
 336         // connect_time.
 337         if (clock_gettime(CLOCK_MONOTONIC_COARSE, &client->connect_time) == -1) {
 338                 log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
 339         } else {
 340                 if (!clients_ordered_by_connect_time.empty() &&
 341                     is_earlier(client->connect_time, clients_ordered_by_connect_time.back().first)) {
 342                         client->connect_time = clients_ordered_by_connect_time.back().first;
 343                 }
 344                 clients_ordered_by_connect_time.push(make_pair(client->connect_time, client->sock));
 345         }
 346 }
 347
 348 int Server::lookup_stream_by_url(const string &url) const
 349 {
 350         const auto stream_url_it = stream_url_map.find(url);
 351         if (stream_url_it == stream_url_map.end()) {
 352                 return -1;
 353         }
 354         return stream_url_it->second;
 355 }
 356
 357 int Server::add_stream(const string &url,
 358                        const string &hls_url,
 359                        size_t backlog_size,
 360                        size_t prebuffering_bytes,
 361                        Stream::Encoding encoding,
 362                        Stream::Encoding src_encoding,
 363                        unsigned hls_frag_duration,
 364                        size_t hls_backlog_margin,
 365                        const string &allow_origin)
 366 {
 367         lock_guard<mutex> lock(mu);
 368         stream_url_map.insert(make_pair(url, streams.size()));
 369         if (!hls_url.empty()) {
 370                 stream_hls_url_map.insert(make_pair(hls_url, streams.size()));
 371         }
 372         streams.emplace_back(new Stream(url, backlog_size, prebuffering_bytes, encoding, src_encoding, hls_frag_duration, hls_backlog_margin, allow_origin));
 373         return streams.size() - 1;
 374 }
 375
 376 int Server::add_stream_from_serialized(const StreamProto &stream, int data_fd)
 377 {
 378         lock_guard<mutex> lock(mu);
 379         stream_url_map.insert(make_pair(stream.url(), streams.size()));
 380         // stream_hls_url_map will be updated in register_hls_url(), since it is not part
 381         // of the serialized state (it will always be picked out from the configuration).
 382         streams.emplace_back(new Stream(stream, data_fd));
 383         return streams.size() - 1;
 384 }
 385
 386 void Server::add_hls_zombie_from_serialized(const HLSZombieProto &zombie_proto)
 387 {
 388         lock_guard<mutex> lock(mu);
 389         HLSZombie zombie;
 390         zombie.remote_addr = zombie_proto.remote_addr();
 391         zombie.url = zombie_proto.url();
 392         zombie.referer = zombie_proto.referer();
 393         zombie.user_agent = zombie_proto.user_agent();
 394         zombie.expires.tv_sec = zombie_proto.expires_sec();
 395         zombie.expires.tv_nsec = zombie_proto.expires_nsec();
 396         hls_zombies[zombie_proto.key()] = move(zombie);
 397 }
 398
 399 void Server::set_backlog_size(int stream_index, size_t new_size)
 400 {
 401         lock_guard<mutex> lock(mu);
 402         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 403         streams[stream_index]->set_backlog_size(new_size);
 404 }
 405
 406 void Server::set_prebuffering_bytes(int stream_index, size_t new_amount)
 407 {
 408         lock_guard<mutex> lock(mu);
 409         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 410         streams[stream_index]->prebuffering_bytes = new_amount;
 411 }
 412
 413 void Server::set_encoding(int stream_index, Stream::Encoding encoding)
 414 {
 415         lock_guard<mutex> lock(mu);
 416         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 417         streams[stream_index]->encoding = encoding;
 418 }
 419
 420 void Server::set_src_encoding(int stream_index, Stream::Encoding encoding)
 421 {
 422         lock_guard<mutex> lock(mu);
 423         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 424         streams[stream_index]->src_encoding = encoding;
 425 }
 426
 427 void Server::set_hls_frag_duration(int stream_index, unsigned hls_frag_duration)
 428 {
 429         lock_guard<mutex> lock(mu);
 430         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 431         streams[stream_index]->hls_frag_duration = hls_frag_duration;
 432 }
 433
 434 void Server::set_hls_backlog_margin(int stream_index, size_t hls_backlog_margin)
 435 {
 436         lock_guard<mutex> lock(mu);
 437         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 438         assert(hls_backlog_margin < streams[stream_index]->backlog_size);
 439         streams[stream_index]->hls_backlog_margin = hls_backlog_margin;
 440 }
 441
 442 void Server::set_allow_origin(int stream_index, const string &allow_origin)
 443 {
 444         lock_guard<mutex> lock(mu);
 445         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 446         streams[stream_index]->allow_origin = allow_origin;
 447 }
 448
 449 void Server::register_hls_url(int stream_index, const string &hls_url)
 450 {
 451         lock_guard<mutex> lock(mu);
 452         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 453         assert(!hls_url.empty());
 454         stream_hls_url_map.insert(make_pair(hls_url, stream_index));
 455 }
 456
 457 void Server::set_header(int stream_index, const string &http_header, const string &stream_header)
 458 {
 459         lock_guard<mutex> lock(mu);
 460         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 461         streams[stream_index]->set_header(http_header, stream_header);
 462 }
 463
 464 void Server::set_pacing_rate(int stream_index, uint32_t pacing_rate)
 465 {
 466         lock_guard<mutex> lock(mu);
 467         assert(clients.empty());
 468         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 469         streams[stream_index]->pacing_rate = pacing_rate;
 470 }
 471
 472 void Server::add_gen204(const std::string &url, const std::string &allow_origin)
 473 {
 474         lock_guard<mutex> lock(mu);
 475         assert(clients.empty());
 476         ping_url_map[url] = allow_origin;
 477 }
 478
 479 void Server::create_tls_context_for_acceptor(const Acceptor *acceptor)
 480 {
 481         assert(acceptor->is_tls());
 482
 483         bool is_server = true;
 484         TLSContext *server_context = tls_create_context(is_server, TLS_V12);
 485
 486         const string &cert = acceptor->get_certificate_chain();
 487         int num_cert = tls_load_certificates(server_context, reinterpret_cast<const unsigned char *>(cert.data()), cert.size());
 488         assert(num_cert > 0);  // Should have been checked by config earlier.
 489
 490         const string &key = acceptor->get_private_key();
 491         int num_key = tls_load_private_key(server_context, reinterpret_cast<const unsigned char *>(key.data()), key.size());
 492         assert(num_key > 0);  // Should have been checked by config earlier.
 493
 494         tls_server_contexts.insert(make_pair(acceptor, server_context));
 495 }
 496
 497 void Server::add_data_deferred(int stream_index, const char *data, size_t bytes, uint16_t metacube_flags, const RationalPTS &pts)
 498 {
 499         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 500         streams[stream_index]->add_data_deferred(data, bytes, metacube_flags, pts);
 501 }
 502
 503 // See the .h file for postconditions after this function.
 504 void Server::process_client(Client *client)
 505 {
 506         switch (client->state) {
 507         case Client::READING_REQUEST: {
 508                 if (client->tls_context != nullptr && !client->in_ktls_mode) {
 509                         if (send_pending_tls_data(client)) {
 510                                 // send_pending_tls_data() hit postconditions #1 or #4.
 511                                 return;
 512                         }
 513                 }
 514
 515 read_request_again:
 516                 // Try to read more of the request.
 517                 char buf[1024];
 518                 int ret;
 519                 if (client->tls_context == nullptr || client->in_ktls_mode) {
 520                         ret = read_plain_data(client, buf, sizeof(buf));
 521                         if (ret == -1) {
 522                                 // read_plain_data() hit postconditions #1 or #2.
 523                                 return;
 524                         }
 525                 } else {
 526                         ret = read_tls_data(client, buf, sizeof(buf));
 527                         if (ret == -1) {
 528                                 // read_tls_data() hit postconditions #1, #2 or #4.
 529                                 return;
 530                         }
 531                 }
 532
 533                 RequestParseStatus status = wait_for_double_newline(&client->request, buf, ret);
 534
 535                 switch (status) {
 536                 case RP_OUT_OF_SPACE:
 537                         log(WARNING, "[%s] Client sent overlong request!", client->remote_addr.c_str());
 538                         close_client(client);
 539                         return;
 540                 case RP_NOT_FINISHED_YET:
 541                         // OK, we don't have the entire header yet. Fine; we'll get it later.
 542                         // See if there's more data for us.
 543                         goto read_request_again;
 544                 case RP_EXTRA_DATA:
 545                         log(WARNING, "[%s] Junk data after request!", client->remote_addr.c_str());
 546                         close_client(client);
 547                         return;
 548                 case RP_FINISHED:
 549                         break;
 550                 }
 551
 552                 assert(status == RP_FINISHED);
 553
 554                 int error_code = parse_request(client);
 555                 if (error_code == 200) {
 556                         if (client->serving_hls_playlist) {
 557                                 construct_hls_playlist(client);
 558                         } else {
 559                                 construct_stream_header(client);
 560                         }
 561                 } else if (error_code == 204) {
 562                         construct_204(client);
 563                 } else {
 564                         construct_error(client, error_code);
 565                 }
 566
 567                 // We've changed states, so fall through.
 568                 assert(client->state == Client::SENDING_SHORT_RESPONSE ||
 569                        client->state == Client::SENDING_HEADER);
 570         }
 571         case Client::SENDING_SHORT_RESPONSE:
 572         case Client::SENDING_HEADER: {
 573 sending_header_or_short_response_again:
 574                 int ret;
 575                 do {
 576                         ret = write(client->sock,
 577                                     client->header_or_short_response->data() + client->header_or_short_response_bytes_sent,
 578                                     client->header_or_short_response->size() - client->header_or_short_response_bytes_sent);
 579                 } while (ret == -1 && errno == EINTR);
 580
 581                 if (ret == -1 && errno == EAGAIN) {
 582                         // We're out of socket space, so now we're at the “low edge” of epoll's
 583                         // edge triggering. epoll will tell us when there is more room, so for now,
 584                         // just return.
 585                         // This is postcondition #4.
 586                         return;
 587                 }
 588
 589                 if (ret == -1) {
 590                         // Error! Postcondition #1.
 591                         log_perror("write");
 592                         close_client(client);
 593                         return;
 594                 }
 595
 596                 client->header_or_short_response_bytes_sent += ret;
 597                 assert(client->header_or_short_response_bytes_sent <= client->header_or_short_response->size());
 598
 599                 if (client->header_or_short_response_bytes_sent < client->header_or_short_response->size()) {
 600                         // We haven't sent all yet. Fine; go another round.
 601                         goto sending_header_or_short_response_again;
 602                 }
 603
 604                 // We're done sending the header or error! Clear it to release some memory.
 605                 client->header_or_short_response = nullptr;
 606                 client->header_or_short_response_holder.clear();
 607                 client->header_or_short_response_ref.reset();
 608
 609                 if (client->state == Client::SENDING_SHORT_RESPONSE) {
 610                         if (more_requests(client)) {
 611                                 // We're done sending the error, but should keep on reading new requests.
 612                                 goto read_request_again;
 613                         } else {
 614                                 // We're done sending the error, so now close.
 615                                 // This is postcondition #1.
 616                                 close_client(client);
 617                         }
 618                         return;
 619                 }
 620
 621                 Stream *stream = client->stream;
 622                 hls_zombies.erase(client->get_hls_zombie_key());
 623                 if (client->stream_pos == Client::STREAM_POS_AT_START) {
 624                         // Start sending from the beginning of the backlog.
 625                         client->stream_pos = min<size_t>(
 626                             stream->bytes_received - stream->backlog_size,
 627                             0);
 628                         client->state = Client::SENDING_DATA;
 629                         goto sending_data;
 630                 } else if (client->stream_pos_end != Client::STREAM_POS_NO_END) {
 631                         // We're sending a fragment, and should have all of it,
 632                         // so start sending right away.
 633                         assert(ssize_t(client->stream_pos) >= 0);
 634                         client->state = Client::SENDING_DATA;
 635                         goto sending_data;
 636                 } else if (stream->prebuffering_bytes == 0) {
 637                         // Start sending from the first keyframe we get. In other
 638                         // words, we won't send any of the backlog, but we'll start
 639                         // sending immediately as we get the next keyframe block.
 640                         // Note that this is functionally identical to the next if branch,
 641                         // except that we save a binary search.
 642                         assert(client->stream_pos == Client::STREAM_POS_AT_END);
 643                         assert(client->stream_pos_end == Client::STREAM_POS_NO_END);
 644                         client->stream_pos = stream->bytes_received;
 645                         client->state = Client::WAITING_FOR_KEYFRAME;
 646                 } else {
 647                         // We're not going to send anything to the client before we have
 648                         // N bytes. However, this wait might be boring; we can just as well
 649                         // use it to send older data if we have it. We use lower_bound()
 650                         // so that we are conservative and never add extra latency over just
 651                         // waiting (assuming CBR or nearly so); otherwise, we could want e.g.
 652                         // 100 kB prebuffer but end up sending a 10 MB GOP.
 653                         assert(client->stream_pos == Client::STREAM_POS_AT_END);
 654                         assert(client->stream_pos_end == Client::STREAM_POS_NO_END);
 655                         deque<uint64_t>::const_iterator starting_point_it =
 656                                 lower_bound(stream->suitable_starting_points.begin(),
 657                                             stream->suitable_starting_points.end(),
 658                                             stream->bytes_received - stream->prebuffering_bytes);
 659                         if (starting_point_it == stream->suitable_starting_points.end()) {
 660                                 // None found. Just put us at the end, and then wait for the
 661                                 // first keyframe to appear.
 662                                 client->stream_pos = stream->bytes_received;
 663                                 client->state = Client::WAITING_FOR_KEYFRAME;
 664                         } else {
 665                                 client->stream_pos = *starting_point_it;
 666                                 client->state = Client::PREBUFFERING;
 667                                 goto prebuffering;
 668                         }
 669                 }
 670                 // Fall through.
 671         }
 672         case Client::WAITING_FOR_KEYFRAME: {
 673                 Stream *stream = client->stream;
 674                 if (stream->suitable_starting_points.empty() ||
 675                     client->stream_pos > stream->suitable_starting_points.back()) {
 676                         // We haven't received a keyframe since this stream started waiting,
 677                         // so keep on waiting for one.
 678                         // This is postcondition #3.
 679                         stream->put_client_to_sleep(client);
 680                         return;
 681                 }
 682                 client->stream_pos = stream->suitable_starting_points.back();
 683                 client->state = Client::PREBUFFERING;
 684                 // Fall through.
 685         }
 686         case Client::PREBUFFERING: {
 687 prebuffering:
 688                 Stream *stream = client->stream;
 689                 size_t bytes_to_send = stream->bytes_received - client->stream_pos;
 690                 assert(bytes_to_send <= stream->backlog_size);
 691                 if (bytes_to_send < stream->prebuffering_bytes) {
 692                         // We don't have enough bytes buffered to start this client yet.
 693                         // This is postcondition #3.
 694                         stream->put_client_to_sleep(client);
 695                         return;
 696                 }
 697                 client->state = Client::SENDING_DATA;
 698                 // Fall through.
 699         }
 700         case Client::SENDING_DATA: {
 701 sending_data:
 702                 skip_lost_data(client);
 703                 Stream *stream = client->stream;
 704
 705 sending_data_again:
 706                 size_t bytes_to_send;
 707                 if (client->stream_pos_end == Client::STREAM_POS_NO_END) {
 708                          bytes_to_send = stream->bytes_received - client->stream_pos;
 709                 } else {
 710                          bytes_to_send = client->stream_pos_end - client->stream_pos;
 711                 }
 712                 assert(bytes_to_send <= stream->backlog_size);
 713                 if (bytes_to_send == 0) {
 714                         if (client->stream_pos == client->stream_pos_end) {  // We have a definite end, and we're at it.
 715                                 // Add (or overwrite) a HLS zombie.
 716                                 timespec now;
 717                                 if (clock_gettime(CLOCK_MONOTONIC_COARSE, &now) == -1) {
 718                                         log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
 719                                 } else {
 720                                         HLSZombie zombie;
 721                                         zombie.remote_addr = client->remote_addr;
 722                                         zombie.referer = client->referer;
 723                                         zombie.user_agent = client->user_agent;
 724                                         zombie.url = client->stream->url + "?frag=<idle>";
 725                                         zombie.expires = now;
 726                                         zombie.expires.tv_sec += client->stream->hls_frag_duration * 3;
 727                                         hls_zombies[client->get_hls_zombie_key()] = move(zombie);
 728                                 }
 729                                 if (more_requests(client)) {
 730                                         // We're done sending the fragment, but should keep on reading new requests.
 731                                         goto read_request_again;
 732                                 } else {
 733                                         // We're done sending the fragment, so now close.
 734                                         // This is postcondition #1.
 735                                         close_client(client);
 736                                 }
 737                         }
 738                         return;
 739                 }
 740
 741                 // See if we need to split across the circular buffer.
 742                 bool more_data = false;
 743                 if ((client->stream_pos % stream->backlog_size) + bytes_to_send > stream->backlog_size) {
 744                         bytes_to_send = stream->backlog_size - (client->stream_pos % stream->backlog_size);
 745                         more_data = true;
 746                 }
 747
 748                 ssize_t ret;
 749                 do {
 750                         off_t offset = client->stream_pos % stream->backlog_size;
 751                         ret = sendfile(client->sock, stream->data_fd, &offset, bytes_to_send);
 752                 } while (ret == -1 && errno == EINTR);
 753
 754                 if (ret == -1 && errno == EAGAIN) {
 755                         // We're out of socket space, so return; epoll will wake us up
 756                         // when there is more room.
 757                         // This is postcondition #4.
 758                         return;
 759                 }
 760                 if (ret == -1) {
 761                         // Error, close; postcondition #1.
 762                         log_perror("sendfile");
 763                         close_client(client);
 764                         return;
 765                 }
 766                 client->stream_pos += ret;
 767                 client->bytes_sent += ret;
 768
 769                 assert(client->stream_pos_end == Client::STREAM_POS_NO_END || client->stream_pos <= client->stream_pos_end);
 770                 if (client->stream_pos == client->stream_pos_end) {
 771                         goto sending_data_again;  // Will see that bytes_to_send == 0 and end.
 772                 } else if (client->stream_pos == stream->bytes_received) {
 773                         // We don't have any more data for this client, so put it to sleep.
 774                         // This is postcondition #3.
 775                         stream->put_client_to_sleep(client);
 776                 } else if (more_data && size_t(ret) == bytes_to_send) {
 777                         goto sending_data_again;
 778                 }
 779                 // We'll also get here for postcondition #4 (similar to the EAGAIN path above).
 780                 break;
 781         }
 782         default:
 783                 assert(false);
 784         }
 785 }
 786
 787 namespace {
 788
 789 void flush_pending_data(int sock)
 790 {
 791         // Flush pending data, which would otherwise wait for the 200ms TCP_CORK timer
 792         // to elapsed; does not cancel out TCP_CORK (since that still takes priority),
 793         // but does a one-off flush.
 794         int one = 1;
 795         if (setsockopt(sock, SOL_TCP, TCP_NODELAY, &one, sizeof(one)) == -1) {
 796                 log_perror("setsockopt(TCP_NODELAY)");
 797                 // Can still continue.
 798         }
 799 }
 800
 801 }  // namespace
 802
 803 bool Server::send_pending_tls_data(Client *client)
 804 {
 805         // See if there's data from the TLS library to write.
 806         if (client->tls_data_to_send == nullptr) {
 807                 client->tls_data_to_send = tls_get_write_buffer(client->tls_context, &client->tls_data_left_to_send);
 808                 if (client->tls_data_to_send == nullptr) {
 809                         // Really no data to send.
 810                         return false;
 811                 }
 812         }
 813
 814 send_data_again:
 815         int ret;
 816         do {
 817                 ret = write(client->sock, client->tls_data_to_send, client->tls_data_left_to_send);
 818         } while (ret == -1 && errno == EINTR);
 819         assert(ret < 0 || size_t(ret) <= client->tls_data_left_to_send);
 820
 821         if (ret == -1 && errno == EAGAIN) {
 822                 // We're out of socket space, so now we're at the “low edge” of epoll's
 823                 // edge triggering. epoll will tell us when there is more room, so for now,
 824                 // just return.
 825                 // This is postcondition #4.
 826                 return true;
 827         }
 828         if (ret == -1) {
 829                 // Error! Postcondition #1.
 830                 log_perror("write");
 831                 close_client(client);
 832                 return true;
 833         }
 834         if (ret > 0 && size_t(ret) == client->tls_data_left_to_send) {
 835                 // All data has been sent, so we don't need to go to sleep
 836                 // (although we are likely to do so immediately afterwards,
 837                 // due to lack of client data).
 838                 tls_buffer_clear(client->tls_context);
 839                 client->tls_data_to_send = nullptr;
 840
 841                 // Flush the data we just wrote, since the client probably
 842                 // is waiting for it.
 843                 flush_pending_data(client->sock);
 844                 return false;
 845         }
 846
 847         // More data to send, so try again.
 848         client->tls_data_to_send += ret;
 849         client->tls_data_left_to_send -= ret;
 850         goto send_data_again;
 851 }
 852
 853 int Server::read_plain_data(Client *client, char *buf, size_t max_size)
 854 {
 855         int ret;
 856         do {
 857                 ret = read(client->sock, buf, max_size);
 858         } while (ret == -1 && errno == EINTR);
 859
 860         if (ret == -1 && errno == EAGAIN) {
 861                 // No more data right now. Nothing to do.
 862                 // This is postcondition #2.
 863                 return -1;
 864         }
 865         if (ret == -1) {
 866                 log_perror("read");
 867                 close_client(client);
 868                 return -1;
 869         }
 870         if (ret == 0) {
 871                 // OK, the socket is closed.
 872                 close_client(client);
 873                 return -1;
 874         }
 875
 876         return ret;
 877 }
 878
 879 int Server::read_tls_data(Client *client, char *buf, size_t max_size)
 880 {
 881 read_again:
 882         assert(!client->in_ktls_mode);
 883
 884         int ret;
 885         do {
 886                 ret = read(client->sock, buf, max_size);
 887         } while (ret == -1 && errno == EINTR);
 888
 889         if (ret == -1 && errno == EAGAIN) {
 890                 // No more data right now. Nothing to do.
 891                 // This is postcondition #2.
 892                 return -1;
 893         }
 894         if (ret == -1) {
 895                 log_perror("read");
 896                 close_client(client);
 897                 return -1;
 898         }
 899         if (ret == 0) {
 900                 // OK, the socket is closed.
 901                 close_client(client);
 902                 return -1;
 903         }
 904
 905         // Give it to the TLS library.
 906         int err = tls_consume_stream(client->tls_context, reinterpret_cast<const unsigned char *>(buf), ret, nullptr);
 907         if (err < 0) {
 908                 log_tls_error("tls_consume_stream", err);
 909                 close_client(client);
 910                 return -1;
 911         }
 912         if (err == 0) {
 913                 // Not consumed any data. See if we can read more.
 914                 goto read_again;
 915         }
 916
 917         // Read any decrypted data available for us. (We can reuse buf, since it's free now.)
 918         ret = tls_read(client->tls_context, reinterpret_cast<unsigned char *>(buf), max_size);
 919         if (ret == 0) {
 920                 // No decrypted data for us yet, but there might be some more handshaking
 921                 // to send. Do that if needed, then look for more data.
 922                 if (send_pending_tls_data(client)) {
 923                         // send_pending_tls_data() hit postconditions #1 or #4.
 924                         return -1;
 925                 }
 926                 goto read_again;
 927         }
 928         if (ret < 0) {
 929                 log_tls_error("tls_read", ret);
 930                 close_client(client);
 931                 return -1;
 932         }
 933
 934         if (tls_established(client->tls_context)) {
 935                 // We're ready to enter kTLS mode, unless we still have some
 936                 // handshake data to send (which then must be sent as non-kTLS).
 937                 if (send_pending_tls_data(client)) {
 938                         // send_pending_tls_data() hit postconditions #1 or #4.
 939                         return -1;
 940                 }
 941                 int err = tls_make_ktls(client->tls_context, client->sock);  // Don't overwrite ret.
 942                 if (err < 0) {
 943                         log_tls_error("tls_make_ktls", ret);
 944                         close_client(client);
 945                         return -1;
 946                 }
 947                 client->in_ktls_mode = true;
 948         }
 949
 950         assert(ret > 0);
 951         return ret;
 952 }
 953
 954 // See if there's some data we've lost. Ideally, we should drop to a block boundary,
 955 // but resync will be the mux's problem.
 956 void Server::skip_lost_data(Client *client)
 957 {
 958         Stream *stream = client->stream;
 959         if (stream == nullptr) {
 960                 return;
 961         }
 962         size_t bytes_to_send = stream->bytes_received - client->stream_pos;
 963         if (bytes_to_send > stream->backlog_size) {
 964                 size_t bytes_lost = bytes_to_send - stream->backlog_size;
 965                 client->bytes_lost += bytes_lost;
 966                 ++client->num_loss_events;
 967                 if (!client->close_after_response) {
 968                         assert(client->stream_pos_end != Client::STREAM_POS_NO_END);
 969
 970                         // We've already sent a Content-Length, so we can't just skip data.
 971                         // Close the connection immediately and hope the other side
 972                         // is able to figure out that there was an error and it needs to skip.
 973                         client->close_after_response = true;
 974                         client->stream_pos = client->stream_pos_end;
 975                 } else {
 976                         client->stream_pos = stream->bytes_received - stream->backlog_size;
 977                 }
 978         }
 979 }
 980
 981 int Server::parse_request(Client *client)
 982 {
 983         vector<string> lines = split_lines(client->request);
 984         client->request.clear();
 985         if (lines.empty()) {
 986                 return 400;  // Bad request (empty).
 987         }
 988
 989         // Parse the headers, for logging purposes.
 990         HTTPHeaderMultimap headers = extract_headers(lines, client->remote_addr);
 991         const auto referer_it = headers.find("Referer");
 992         if (referer_it != headers.end()) {
 993                 client->referer = referer_it->second;
 994         }
 995         const auto user_agent_it = headers.find("User-Agent");
 996         if (user_agent_it != headers.end()) {
 997                 client->user_agent = user_agent_it->second;
 998         }
 999         const auto x_playback_session_id_it = headers.find("X-Playback-Session-Id");
1000         if (x_playback_session_id_it != headers.end()) {
1001                 client->x_playback_session_id = x_playback_session_id_it->second;
1002         } else {
1003                 client->x_playback_session_id.clear();
1004         }
1005
1006         vector<string> request_tokens = split_tokens(lines[0]);
1007         if (request_tokens.size() < 3) {
1008                 return 400;  // Bad request (empty).
1009         }
1010         if (request_tokens[0] != "GET") {
1011                 return 400;  // Should maybe be 405 instead?
1012         }
1013
1014         string url = request_tokens[1];
1015         client->url = url;
1016         if (url.size() > 8 && url.find("?backlog") == url.size() - 8) {
1017                 client->stream_pos = Client::STREAM_POS_AT_START;
1018                 url = url.substr(0, url.size() - 8);
1019         } else {
1020                 size_t pos = url.find("?frag=");
1021                 if (pos != string::npos) {
1022                         // Parse an endpoint of the type /stream.mp4?frag=1234-5678.
1023                         const char *ptr = url.c_str() + pos + 6;
1024
1025                         // "?frag=header" is special.
1026                         if (strcmp(ptr, "header") == 0) {
1027                                 client->stream_pos = Client::STREAM_POS_HEADER_ONLY;
1028                                 client->stream_pos_end = -1;
1029                         } else {
1030                                 char *endptr;
1031                                 long long frag_start = strtol(ptr, &endptr, 10);
1032                                 if (ptr == endptr || frag_start < 0 || frag_start == LLONG_MAX) {
1033                                         return 400;  // Bad request.
1034                                 }
1035                                 if (*endptr != '-') {
1036                                         return 400;  // Bad request.
1037                                 }
1038                                 ptr = endptr + 1;
1039
1040                                 long long frag_end = strtol(ptr, &endptr, 10);
1041                                 if (ptr == endptr || frag_end < frag_start || frag_end == LLONG_MAX) {
1042                                         return 400;  // Bad request.
1043                                 }
1044
1045                                 if (*endptr != '\0') {
1046                                         return 400;  // Bad request.
1047                                 }
1048
1049                                 client->stream_pos = frag_start;
1050                                 client->stream_pos_end = frag_end;
1051                         }
1052                         url = url.substr(0, pos);
1053                 } else {
1054                         client->stream_pos = -1;
1055                         client->stream_pos_end = -1;
1056                 }
1057         }
1058
1059         // Figure out if we're supposed to close the socket after we've delivered the response.
1060         string protocol = request_tokens[2];
1061         if (protocol.find("HTTP/") != 0) {
1062                 return 400;  // Bad request.
1063         }
1064         client->close_after_response = false;
1065         client->http_11 = true;
1066         if (protocol == "HTTP/1.0") {
1067                 // No persistent connections.
1068                 client->close_after_response = true;
1069                 client->http_11 = false;
1070         } else {
1071                 const auto connection_it = headers.find("Connection");
1072                 if (connection_it != headers.end() && connection_it->second == "close") {
1073                         client->close_after_response = true;
1074                 }
1075         }
1076
1077         const auto stream_url_map_it = stream_url_map.find(url);
1078         if (stream_url_map_it != stream_url_map.end()) {
1079                 // Serve a regular stream..
1080                 client->stream = streams[stream_url_map_it->second].get();
1081                 client->serving_hls_playlist = false;
1082         } else {
1083                 const auto stream_hls_url_map_it = stream_hls_url_map.find(url);
1084                 if (stream_hls_url_map_it != stream_hls_url_map.end()) {
1085                         // Serve HLS playlist.
1086                         client->stream = streams[stream_hls_url_map_it->second].get();
1087                         client->serving_hls_playlist = true;
1088                 } else {
1089                         const auto ping_url_map_it = ping_url_map.find(url);
1090                         if (ping_url_map_it == ping_url_map.end()) {
1091                                 return 404;  // Not found.
1092                         } else {
1093                                 // Serve a ping (204 no error).
1094                                 return 204;
1095                         }
1096                 }
1097         }
1098
1099         Stream *stream = client->stream;
1100
1101         if (client->serving_hls_playlist) {
1102                 if (stream->encoding == Stream::STREAM_ENCODING_METACUBE) {
1103                         // This doesn't make any sense, and is hard to implement, too.
1104                         return 404;
1105                 } else {
1106                         return 200;
1107                 }
1108         }
1109
1110         if (client->stream_pos_end == Client::STREAM_POS_NO_END) {
1111                 if (stream->http_header.empty()) {
1112                         return 503;  // Service unavailable.
1113                 }
1114
1115                 // This stream won't end, so we don't have a content-length,
1116                 // and can just as well tell the client it's Connection: close
1117                 // (otherwise, we'd have to implement chunking TE for no good reason).
1118                 client->close_after_response = true;
1119         } else {
1120                 if (stream->encoding == Stream::STREAM_ENCODING_METACUBE) {
1121                         // This doesn't make any sense, and is hard to implement, too.
1122                         return 416;  // Range not satisfiable.
1123                 }
1124
1125                 // Check that we have the requested fragment in our backlog.
1126                 size_t buffer_end = stream->bytes_received;
1127                 size_t buffer_start = (buffer_end <= stream->backlog_size) ? 0 : buffer_end - stream->backlog_size;
1128
1129                 if (client->stream_pos_end > buffer_end ||
1130                     client->stream_pos < buffer_start) {
1131                         return 416;  // Range not satisfiable.
1132                 }
1133         }
1134
1135         client->stream = stream;
1136         if (setsockopt(client->sock, SOL_SOCKET, SO_MAX_PACING_RATE, &client->stream->pacing_rate, sizeof(client->stream->pacing_rate)) == -1) {
1137                 if (client->stream->pacing_rate != ~0U) {
1138                         log_perror("setsockopt(SO_MAX_PACING_RATE)");
1139                 }
1140         }
1141         client->request.clear();
1142
1143         return 200;  // OK!
1144 }
1145
1146 void Server::construct_stream_header(Client *client)
1147 {
1148         Stream *stream = client->stream;
1149         string response = stream->http_header;
1150         if (client->stream_pos == Client::STREAM_POS_HEADER_ONLY) {
1151                 char buf[64];
1152                 snprintf(buf, sizeof(buf), "Content-Length: %zu\r\n", stream->stream_header.size());
1153                 response.append(buf);
1154         } else if (client->stream_pos_end != Client::STREAM_POS_NO_END) {
1155                 char buf[64];
1156                 snprintf(buf, sizeof(buf), "Content-Length: %" PRIu64 "\r\n", client->stream_pos_end - client->stream_pos);
1157                 response.append(buf);
1158         }
1159         if (client->http_11) {
1160                 assert(response.find("HTTP/1.0") == 0);
1161                 response[7] = '1';  // Change to HTTP/1.1.
1162                 if (client->close_after_response) {
1163                         response.append("Connection: close\r\n");
1164                 }
1165         } else {
1166                 assert(client->close_after_response);
1167         }
1168         if (!stream->allow_origin.empty()) {
1169                 response.append("Access-Control-Allow-Origin: ");
1170                 response.append(stream->allow_origin);
1171                 response.append("\r\n");
1172         }
1173         if (stream->encoding == Stream::STREAM_ENCODING_RAW) {
1174                 response.append("\r\n");
1175         } else if (stream->encoding == Stream::STREAM_ENCODING_METACUBE) {
1176                 response.append("Content-Encoding: metacube\r\n\r\n");
1177                 if (!stream->stream_header.empty()) {
1178                         metacube2_block_header hdr;
1179                         memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
1180                         hdr.size = htonl(stream->stream_header.size());
1181                         hdr.flags = htons(METACUBE_FLAGS_HEADER);
1182                         hdr.csum = htons(metacube2_compute_crc(&hdr));
1183                         response.append(string(reinterpret_cast<char *>(&hdr), sizeof(hdr)));
1184                 }
1185         } else {
1186                 assert(false);
1187         }
1188         if (client->stream_pos == Client::STREAM_POS_HEADER_ONLY) {
1189                 client->state = Client::SENDING_SHORT_RESPONSE;
1190                 response.append(stream->stream_header);
1191         } else {
1192                 client->state = Client::SENDING_HEADER;
1193                 if (client->stream_pos_end == Client::STREAM_POS_NO_END) {  // Fragments don't contain stream headers.
1194                         response.append(stream->stream_header);
1195                 }
1196         }
1197
1198         client->header_or_short_response_holder = move(response);
1199         client->header_or_short_response = &client->header_or_short_response_holder;
1200
1201         // Switch states.
1202         change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
1203 }
1204
1205 void Server::construct_error(Client *client, int error_code)
1206 {
1207         char error[256];
1208         if (client->http_11 && client->close_after_response) {
1209                 snprintf(error, sizeof(error),
1210                         "HTTP/1.1 %d Error\r\nContent-Type: text/plain\r\nConnection: close\r\n\r\nSomething went wrong. Sorry.\r\n",
1211                         error_code);
1212         } else {
1213                 snprintf(error, sizeof(error),
1214                         "HTTP/1.%d %d Error\r\nContent-Type: text/plain\r\nContent-Length: 30\r\n\r\nSomething went wrong. Sorry.\r\n",
1215                         client->http_11, error_code);
1216         }
1217         client->header_or_short_response_holder = error;
1218         client->header_or_short_response = &client->header_or_short_response_holder;
1219
1220         // Switch states.
1221         client->state = Client::SENDING_SHORT_RESPONSE;
1222         change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
1223 }
1224
1225 void Server::construct_hls_playlist(Client *client)
1226 {
1227         Stream *stream = client->stream;
1228         shared_ptr<const string> *cache;
1229         if (client->http_11) {
1230                 if (client->close_after_response) {
1231                         cache = &stream->hls_playlist_http11_close;
1232                 } else {
1233                         cache = &stream->hls_playlist_http11_persistent;
1234                 }
1235         } else {
1236                 assert(client->close_after_response);
1237                 cache = &stream->hls_playlist_http10;
1238         }
1239
1240         if (*cache == nullptr) {
1241                 *cache = stream->generate_hls_playlist(client->http_11, client->close_after_response);
1242         }
1243         client->header_or_short_response_ref = *cache;
1244         client->header_or_short_response = cache->get();
1245
1246         // Switch states.
1247         client->state = Client::SENDING_SHORT_RESPONSE;
1248         change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
1249 }
1250
1251 void Server::construct_204(Client *client)
1252 {
1253         const auto ping_url_map_it = ping_url_map.find(client->url);
1254         assert(ping_url_map_it != ping_url_map.end());
1255
1256         string response;
1257         if (client->http_11) {
1258                 response = "HTTP/1.1 204 No Content\r\n";
1259                 if (client->close_after_response) {
1260                         response.append("Connection: close\r\n");
1261                 }
1262         } else {
1263                 response = "HTTP/1.0 204 No Content\r\n";
1264                 assert(client->close_after_response);
1265         }
1266         if (!ping_url_map_it->second.empty()) {
1267                 response.append("Access-Control-Allow-Origin: ");
1268                 response.append(ping_url_map_it->second);
1269                 response.append("\r\n");
1270         }
1271         response.append("\r\n");
1272
1273         client->header_or_short_response_holder = move(response);
1274         client->header_or_short_response = &client->header_or_short_response_holder;
1275
1276         // Switch states.
1277         client->state = Client::SENDING_SHORT_RESPONSE;
1278         change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
1279 }
1280
1281 namespace {
1282
1283 template<class T>
1284 void delete_from(vector<T> *v, T elem)
1285 {
1286         typename vector<T>::iterator new_end = remove(v->begin(), v->end(), elem);
1287         v->erase(new_end, v->end());
1288 }
1289
1290 void send_ktls_close(int sock)
1291 {
1292         uint8_t record_type = 21;  // Alert.
1293         uint8_t body[] = {
1294                 1,   // Warning level (but still fatal!).
1295                 0,   // close_notify.
1296         };
1297
1298         int cmsg_len = sizeof(record_type);
1299         char buf[CMSG_SPACE(cmsg_len)];
1300
1301         msghdr msg = {0};
1302         msg.msg_control = buf;
1303         msg.msg_controllen = sizeof(buf);
1304         cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
1305         cmsg->cmsg_level = SOL_TLS;
1306         cmsg->cmsg_type = TLS_SET_RECORD_TYPE;
1307         cmsg->cmsg_len = CMSG_LEN(cmsg_len);
1308         *CMSG_DATA(cmsg) = record_type;
1309         msg.msg_controllen = cmsg->cmsg_len;
1310
1311         iovec msg_iov;
1312         msg_iov.iov_base = body;
1313         msg_iov.iov_len = sizeof(body);
1314         msg.msg_iov = &msg_iov;
1315         msg.msg_iovlen = 1;
1316
1317         int err;
1318         do {
1319                 err = sendmsg(sock, &msg, 0);
1320         } while (err == -1 && errno == EINTR);  // Ignore all other errors.
1321 }
1322
1323 }  // namespace
1324
1325 void Server::close_client(Client *client)
1326 {
1327         if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, client->sock, nullptr) == -1) {
1328                 log_perror("epoll_ctl(EPOLL_CTL_DEL)");
1329                 exit(1);
1330         }
1331
1332         // This client could be sleeping, so we'll need to fix that. (Argh, O(n).)
1333         if (client->stream != nullptr) {
1334                 delete_from(&client->stream->sleeping_clients, client);
1335                 delete_from(&client->stream->to_process, client);
1336         }
1337
1338         if (client->tls_context) {
1339                 if (client->in_ktls_mode) {
1340                         // Keep GnuTLS happy.
1341                         send_ktls_close(client->sock);
1342                 }
1343                 tls_destroy_context(client->tls_context);
1344         }
1345
1346         // Log to access_log.
1347         access_log->write(client->get_stats());
1348
1349         // Bye-bye!
1350         safe_close(client->sock);
1351
1352         clients.erase(client->sock);
1353 }
1354
1355 void Server::change_epoll_events(Client *client, uint32_t events)
1356 {
1357         epoll_event ev;
1358         ev.events = events;
1359         ev.data.ptr = client;
1360
1361         if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
1362                 log_perror("epoll_ctl(EPOLL_CTL_MOD)");
1363                 exit(1);
1364         }
1365 }
1366
1367 bool Server::more_requests(Client *client)
1368 {
1369         if (client->close_after_response) {
1370                 return false;
1371         }
1372
1373         // Log to access_log.
1374         access_log->write(client->get_stats());
1375
1376         flush_pending_data(client->sock);
1377
1378         // Switch states and reset the parsers. We don't reset statistics.
1379         client->state = Client::READING_REQUEST;
1380         client->url.clear();
1381         client->stream = NULL;
1382         client->header_or_short_response = nullptr;
1383         client->header_or_short_response_holder.clear();
1384         client->header_or_short_response_ref.reset();
1385         client->header_or_short_response_bytes_sent = 0;
1386         client->bytes_sent = 0;
1387         start_client_timeout_timer(client);
1388
1389         change_epoll_events(client, EPOLLIN | EPOLLET | EPOLLRDHUP);  // No TLS handshake, so no EPOLLOUT needed.
1390
1391         return true;
1392 }
1393
1394 void Server::process_queued_data()
1395 {
1396         {
1397                 lock_guard<mutex> lock(queued_clients_mutex);
1398
1399                 for (const pair<int, Acceptor *> &id_and_acceptor : queued_add_clients) {
1400                         add_client(id_and_acceptor.first, id_and_acceptor.second);
1401                 }
1402                 queued_add_clients.clear();
1403         }
1404
1405         for (unique_ptr<Stream> &stream : streams) {
1406                 stream->process_queued_data();
1407         }
1408 }