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_create1(EPOLL_CLOEXEC);
  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         // We're going to die soon anyway, but clean this up to keep leak checking happy.
  75         for (const auto &acceptor_and_context : tls_server_contexts) {
  76                 tls_destroy_context(acceptor_and_context.second);
  77         }
  78 }
  79
  80 vector<ClientStats> Server::get_client_stats() const
  81 {
  82         vector<ClientStats> ret;
  83
  84         lock_guard<mutex> lock(mu);
  85         for (const auto &fd_and_client : clients) {
  86                 ret.push_back(fd_and_client.second.get_stats());
  87         }
  88         return ret;
  89 }
  90
  91 vector<HLSZombie> Server::get_hls_zombies()
  92 {
  93         vector<HLSZombie> ret;
  94
  95         timespec now;
  96         if (clock_gettime(CLOCK_MONOTONIC_COARSE, &now) == -1) {
  97                 log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
  98                 return ret;
  99         }
 100
 101         lock_guard<mutex> lock(mu);
 102         for (auto it = hls_zombies.begin(); it != hls_zombies.end(); ) {
 103                 if (is_earlier(it->second.expires, now)) {
 104                         hls_zombies.erase(it++);
 105                 } else {
 106                         ret.push_back(it->second);
 107                         ++it;
 108                 }
 109         }
 110         return ret;
 111 }
 112
 113 void Server::do_work()
 114 {
 115         while (!should_stop()) {
 116                 // Wait until there's activity on at least one of the fds,
 117                 // or 20 ms (about one frame at 50 fps) has elapsed.
 118                 //
 119                 // We could in theory wait forever and rely on wakeup()
 120                 // from add_client_deferred() and add_data_deferred(),
 121                 // but wakeup is a pretty expensive operation, and the
 122                 // two threads might end up fighting over a lock, so it's
 123                 // seemingly (much) more efficient to just have a timeout here.
 124                 int nfds = epoll_pwait(epoll_fd, events, EPOLL_MAX_EVENTS, EPOLL_TIMEOUT_MS, &sigset_without_usr1_block);
 125                 if (nfds == -1 && errno != EINTR) {
 126                         log_perror("epoll_wait");
 127                         exit(1);
 128                 }
 129
 130                 lock_guard<mutex> lock(mu);  // We release the mutex between iterations.
 131
 132                 process_queued_data();
 133
 134                 // Process each client where we have socket activity.
 135                 for (int i = 0; i < nfds; ++i) {
 136                         Client *client = reinterpret_cast<Client *>(events[i].data.ptr);
 137
 138                         if (events[i].events & (EPOLLERR | EPOLLRDHUP | EPOLLHUP)) {
 139                                 close_client(client);
 140                                 continue;
 141                         }
 142
 143                         process_client(client);
 144                 }
 145
 146                 // Process each client where its stream has new data,
 147                 // even if there was no socket activity.
 148                 for (unique_ptr<Stream> &stream : streams) {
 149                         vector<Client *> to_process;
 150                         swap(stream->to_process, to_process);
 151                         for (Client *client : to_process) {
 152                                 process_client(client);
 153                         }
 154                 }
 155
 156                 // Finally, go through each client to see if it's timed out
 157                 // in the READING_REQUEST state. (Seemingly there are clients
 158                 // that can hold sockets up for days at a time without sending
 159                 // anything at all.)
 160                 timespec timeout_time;
 161                 if (clock_gettime(CLOCK_MONOTONIC_COARSE, &timeout_time) == -1) {
 162                         log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
 163                         continue;
 164                 }
 165                 timeout_time.tv_sec -= REQUEST_READ_TIMEOUT_SEC;
 166                 while (!clients_ordered_by_connect_time.empty()) {
 167                         const pair<timespec, int> &connect_time_and_fd = clients_ordered_by_connect_time.front();
 168
 169                         // See if we have reached the end of clients to process.
 170                         if (is_earlier(timeout_time, connect_time_and_fd.first)) {
 171                                 break;
 172                         }
 173
 174                         // If this client doesn't exist anymore, just ignore it
 175                         // (it was deleted earlier).
 176                         auto client_it = clients.find(connect_time_and_fd.second);
 177                         if (client_it == clients.end()) {
 178                                 clients_ordered_by_connect_time.pop();
 179                                 continue;
 180                         }
 181                         Client *client = &client_it->second;
 182                         if (!is_equal(client->connect_time, connect_time_and_fd.first)) {
 183                                 // Another client has taken this fd in the meantime.
 184                                 clients_ordered_by_connect_time.pop();
 185                                 continue;
 186                         }
 187
 188                         if (client->state != Client::READING_REQUEST) {
 189                                 // Only READING_REQUEST can time out.
 190                                 clients_ordered_by_connect_time.pop();
 191                                 continue;
 192                         }
 193
 194                         // OK, it timed out.
 195                         close_client(client);
 196                         clients_ordered_by_connect_time.pop();
 197                 }
 198         }
 199 }
 200
 201 CubemapStateProto Server::serialize(unordered_map<const string *, size_t> *short_response_pool)
 202 {
 203         // We don't serialize anything queued, so empty the queues.
 204         process_queued_data();
 205
 206         // Set all clients in a consistent state before serializing
 207         // (ie., they have no remaining lost data). Otherwise, increasing
 208         // the backlog could take clients into a newly valid area of the backlog,
 209         // sending a stream of zeros instead of skipping the data as it should.
 210         //
 211         // TODO: Do this when clients are added back from serialized state instead;
 212         // it would probably be less wasteful.
 213         for (auto &fd_and_client : clients) {
 214                 skip_lost_data(&fd_and_client.second);
 215         }
 216
 217         CubemapStateProto serialized;
 218         for (const auto &fd_and_client : clients) {
 219                 serialized.add_clients()->MergeFrom(fd_and_client.second.serialize(short_response_pool));
 220         }
 221         for (unique_ptr<Stream> &stream : streams) {
 222                 serialized.add_streams()->MergeFrom(stream->serialize());
 223         }
 224         for (const auto &key_and_zombie : hls_zombies) {
 225                 HLSZombieProto *proto = serialized.add_hls_zombies();
 226                 proto->set_key(key_and_zombie.first);
 227
 228                 const HLSZombie &zombie = key_and_zombie.second;
 229                 proto->set_remote_addr(zombie.remote_addr);
 230                 proto->set_url(zombie.url);
 231                 proto->set_referer(zombie.referer);
 232                 proto->set_user_agent(zombie.user_agent);
 233                 proto->set_expires_sec(zombie.expires.tv_sec);
 234                 proto->set_expires_nsec(zombie.expires.tv_nsec);
 235         }
 236         return serialized;
 237 }
 238
 239 void Server::add_client_deferred(int sock, Acceptor *acceptor)
 240 {
 241         lock_guard<mutex> lock(queued_clients_mutex);
 242         queued_add_clients.push_back(std::make_pair(sock, acceptor));
 243 }
 244
 245 void Server::add_client(int sock, Acceptor *acceptor)
 246 {
 247         const bool is_tls = acceptor->is_tls();
 248         auto inserted = clients.insert(make_pair(sock, Client(sock)));
 249         assert(inserted.second == true);  // Should not already exist.
 250         Client *client_ptr = &inserted.first->second;
 251
 252         start_client_timeout_timer(client_ptr);
 253
 254         // Start listening on data from this socket.
 255         epoll_event ev;
 256         if (is_tls) {
 257                 // Even in the initial state (READING_REQUEST), TLS needs to
 258                 // send data for the handshake, and thus might end up needing
 259                 // to know about EPOLLOUT.
 260                 ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLRDHUP;
 261         } else {
 262                 // EPOLLOUT will be added once we go out of READING_REQUEST.
 263                 ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
 264         }
 265         ev.data.ptr = client_ptr;
 266         if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sock, &ev) == -1) {
 267                 log_perror("epoll_ctl(EPOLL_CTL_ADD)");
 268                 exit(1);
 269         }
 270
 271         if (is_tls) {
 272                 assert(tls_server_contexts.count(acceptor));
 273                 client_ptr->tls_context = tls_accept(tls_server_contexts[acceptor]);
 274                 if (client_ptr->tls_context == nullptr) {
 275                         log(ERROR, "tls_accept() failed");
 276                         close_client(client_ptr);
 277                         return;
 278                 }
 279                 tls_make_exportable(client_ptr->tls_context, 1);
 280         }
 281
 282         process_client(client_ptr);
 283 }
 284
 285 void Server::add_client_from_serialized(const ClientProto &client, const vector<shared_ptr<const string>> &short_responses)
 286 {
 287         lock_guard<mutex> lock(mu);
 288         Stream *stream;
 289         int stream_index = lookup_stream_by_url(client.url());
 290         if (stream_index == -1) {
 291                 assert(client.state() != Client::SENDING_DATA);
 292                 stream = nullptr;
 293         } else {
 294                 stream = streams[stream_index].get();
 295         }
 296         auto inserted = clients.insert(make_pair(client.sock(), Client(client, short_responses, stream)));
 297         assert(inserted.second == true);  // Should not already exist.
 298         Client *client_ptr = &inserted.first->second;
 299
 300         // Connection timestamps must be nondecreasing.
 301         assert(clients_ordered_by_connect_time.empty() ||
 302                !is_earlier(client_ptr->connect_time, clients_ordered_by_connect_time.back().first));
 303         clients_ordered_by_connect_time.push(make_pair(client_ptr->connect_time, client.sock()));
 304
 305         // Start listening on data from this socket.
 306         epoll_event ev;
 307         if (client.state() == Client::READING_REQUEST) {
 308                 // See the corresponding comment in Server::add_client().
 309                 if (client.has_tls_context()) {
 310                         ev.events = EPOLLIN | EPOLLOUT | EPOLLET | EPOLLRDHUP;
 311                 } else {
 312                         ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
 313                 }
 314         } else {
 315                 // If we don't have more data for this client, we'll be putting it into
 316                 // the sleeping array again soon.
 317                 ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
 318         }
 319         ev.data.ptr = client_ptr;
 320         if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client.sock(), &ev) == -1) {
 321                 log_perror("epoll_ctl(EPOLL_CTL_ADD)");
 322                 exit(1);
 323         }
 324
 325         if (client_ptr->state == Client::WAITING_FOR_KEYFRAME ||
 326             client_ptr->state == Client::PREBUFFERING ||
 327             (client_ptr->state == Client::SENDING_DATA &&
 328              client_ptr->stream_pos == client_ptr->stream->bytes_received)) {
 329                 client_ptr->stream->put_client_to_sleep(client_ptr);
 330         } else {
 331                 process_client(client_ptr);
 332         }
 333 }
 334
 335 void Server::start_client_timeout_timer(Client *client)
 336 {
 337         // Connection timestamps must be nondecreasing. I can't find any guarantee
 338         // that even the monotonic clock can't go backwards by a small amount
 339         // (think switching between CPUs with non-synchronized TSCs), so if
 340         // this actually should happen, we hack around it by fudging
 341         // connect_time.
 342         if (clock_gettime(CLOCK_MONOTONIC_COARSE, &client->connect_time) == -1) {
 343                 log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
 344         } else {
 345                 if (!clients_ordered_by_connect_time.empty() &&
 346                     is_earlier(client->connect_time, clients_ordered_by_connect_time.back().first)) {
 347                         client->connect_time = clients_ordered_by_connect_time.back().first;
 348                 }
 349                 clients_ordered_by_connect_time.push(make_pair(client->connect_time, client->sock));
 350         }
 351 }
 352
 353 int Server::lookup_stream_by_url(const string &url) const
 354 {
 355         const auto stream_url_it = stream_url_map.find(url);
 356         if (stream_url_it == stream_url_map.end()) {
 357                 return -1;
 358         }
 359         return stream_url_it->second;
 360 }
 361
 362 int Server::add_stream(const string &url,
 363                        const string &hls_url,
 364                        size_t backlog_size,
 365                        size_t prebuffering_bytes,
 366                        Stream::Encoding encoding,
 367                        Stream::Encoding src_encoding,
 368                        unsigned hls_frag_duration,
 369                        size_t hls_backlog_margin,
 370                        const string &allow_origin)
 371 {
 372         lock_guard<mutex> lock(mu);
 373         stream_url_map.insert(make_pair(url, streams.size()));
 374         if (!hls_url.empty()) {
 375                 stream_hls_url_map.insert(make_pair(hls_url, streams.size()));
 376         }
 377         streams.emplace_back(new Stream(url, backlog_size, prebuffering_bytes, encoding, src_encoding, hls_frag_duration, hls_backlog_margin, allow_origin));
 378         return streams.size() - 1;
 379 }
 380
 381 int Server::add_stream_from_serialized(const StreamProto &stream, int data_fd)
 382 {
 383         lock_guard<mutex> lock(mu);
 384         stream_url_map.insert(make_pair(stream.url(), streams.size()));
 385         // stream_hls_url_map will be updated in register_hls_url(), since it is not part
 386         // of the serialized state (it will always be picked out from the configuration).
 387         streams.emplace_back(new Stream(stream, data_fd));
 388         return streams.size() - 1;
 389 }
 390
 391 void Server::add_hls_zombie_from_serialized(const HLSZombieProto &zombie_proto)
 392 {
 393         lock_guard<mutex> lock(mu);
 394         HLSZombie zombie;
 395         zombie.remote_addr = zombie_proto.remote_addr();
 396         zombie.url = zombie_proto.url();
 397         zombie.referer = zombie_proto.referer();
 398         zombie.user_agent = zombie_proto.user_agent();
 399         zombie.expires.tv_sec = zombie_proto.expires_sec();
 400         zombie.expires.tv_nsec = zombie_proto.expires_nsec();
 401         hls_zombies[zombie_proto.key()] = move(zombie);
 402 }
 403
 404 void Server::set_backlog_size(int stream_index, size_t new_size)
 405 {
 406         lock_guard<mutex> lock(mu);
 407         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 408         streams[stream_index]->set_backlog_size(new_size);
 409 }
 410
 411 void Server::set_prebuffering_bytes(int stream_index, size_t new_amount)
 412 {
 413         lock_guard<mutex> lock(mu);
 414         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 415         streams[stream_index]->prebuffering_bytes = new_amount;
 416 }
 417
 418 void Server::set_encoding(int stream_index, Stream::Encoding encoding)
 419 {
 420         lock_guard<mutex> lock(mu);
 421         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 422         streams[stream_index]->encoding = encoding;
 423 }
 424
 425 void Server::set_src_encoding(int stream_index, Stream::Encoding encoding)
 426 {
 427         lock_guard<mutex> lock(mu);
 428         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 429         streams[stream_index]->src_encoding = encoding;
 430 }
 431
 432 void Server::set_hls_frag_duration(int stream_index, unsigned hls_frag_duration)
 433 {
 434         lock_guard<mutex> lock(mu);
 435         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 436         streams[stream_index]->hls_frag_duration = hls_frag_duration;
 437 }
 438
 439 void Server::set_hls_backlog_margin(int stream_index, size_t hls_backlog_margin)
 440 {
 441         lock_guard<mutex> lock(mu);
 442         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 443         assert(hls_backlog_margin < streams[stream_index]->backlog_size);
 444         streams[stream_index]->hls_backlog_margin = hls_backlog_margin;
 445 }
 446
 447 void Server::set_allow_origin(int stream_index, const string &allow_origin)
 448 {
 449         lock_guard<mutex> lock(mu);
 450         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 451         streams[stream_index]->allow_origin = allow_origin;
 452 }
 453
 454 void Server::register_hls_url(int stream_index, const string &hls_url)
 455 {
 456         lock_guard<mutex> lock(mu);
 457         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 458         assert(!hls_url.empty());
 459         stream_hls_url_map.insert(make_pair(hls_url, stream_index));
 460 }
 461
 462 void Server::set_header(int stream_index, const string &http_header, const string &stream_header)
 463 {
 464         lock_guard<mutex> lock(mu);
 465         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 466         streams[stream_index]->set_header(http_header, stream_header);
 467 }
 468
 469 void Server::set_unavailable(int stream_index)
 470 {
 471         lock_guard<mutex> lock(mu);
 472         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 473         streams[stream_index]->set_unavailable();
 474 }
 475
 476 void Server::set_pacing_rate(int stream_index, uint32_t pacing_rate)
 477 {
 478         lock_guard<mutex> lock(mu);
 479         assert(clients.empty());
 480         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 481         streams[stream_index]->pacing_rate = pacing_rate;
 482 }
 483
 484 void Server::add_gen204(const std::string &url, const std::string &allow_origin)
 485 {
 486         lock_guard<mutex> lock(mu);
 487         assert(clients.empty());
 488         ping_url_map[url] = allow_origin;
 489 }
 490
 491 void Server::create_tls_context_for_acceptor(const Acceptor *acceptor)
 492 {
 493         assert(acceptor->is_tls());
 494
 495         bool is_server = true;
 496         TLSContext *server_context = tls_create_context(is_server, TLS_V12);
 497
 498         const string &cert = acceptor->get_certificate_chain();
 499         int num_cert = tls_load_certificates(server_context, reinterpret_cast<const unsigned char *>(cert.data()), cert.size());
 500         assert(num_cert > 0);  // Should have been checked by config earlier.
 501
 502         const string &key = acceptor->get_private_key();
 503         int num_key = tls_load_private_key(server_context, reinterpret_cast<const unsigned char *>(key.data()), key.size());
 504         assert(num_key > 0);  // Should have been checked by config earlier.
 505
 506         tls_server_contexts.insert(make_pair(acceptor, server_context));
 507 }
 508
 509 void Server::add_data_deferred(int stream_index, const char *data, size_t bytes, uint16_t metacube_flags, const RationalPTS &pts)
 510 {
 511         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 512         streams[stream_index]->add_data_deferred(data, bytes, metacube_flags, pts);
 513 }
 514
 515 // See the .h file for postconditions after this function.
 516 void Server::process_client(Client *client)
 517 {
 518         switch (client->state) {
 519         case Client::READING_REQUEST: {
 520                 if (client->tls_context != nullptr && !client->in_ktls_mode) {
 521                         if (send_pending_tls_data(client)) {
 522                                 // send_pending_tls_data() hit postconditions #1 or #4.
 523                                 return;
 524                         }
 525                 }
 526
 527 read_request_again:
 528                 // Try to read more of the request.
 529                 char buf[1024];
 530                 int ret;
 531                 if (client->tls_context == nullptr || client->in_ktls_mode) {
 532                         ret = read_plain_data(client, buf, sizeof(buf));
 533                         if (ret == -1) {
 534                                 // read_plain_data() hit postconditions #1 or #2.
 535                                 return;
 536                         }
 537                 } else {
 538                         ret = read_tls_data(client, buf, sizeof(buf));
 539                         if (ret == -1) {
 540                                 // read_tls_data() hit postconditions #1, #2 or #4.
 541                                 return;
 542                         }
 543                 }
 544
 545                 RequestParseStatus status = wait_for_double_newline(&client->request, buf, ret);
 546
 547                 switch (status) {
 548                 case RP_OUT_OF_SPACE:
 549                         log(WARNING, "[%s] Client sent overlong request!", client->remote_addr.c_str());
 550                         close_client(client);
 551                         return;
 552                 case RP_NOT_FINISHED_YET:
 553                         // OK, we don't have the entire header yet. Fine; we'll get it later.
 554                         // See if there's more data for us.
 555                         goto read_request_again;
 556                 case RP_EXTRA_DATA:
 557                         log(WARNING, "[%s] Junk data after request!", client->remote_addr.c_str());
 558                         close_client(client);
 559                         return;
 560                 case RP_FINISHED:
 561                         break;
 562                 }
 563
 564                 assert(status == RP_FINISHED);
 565
 566                 int error_code = parse_request(client);
 567                 if (error_code == 200) {
 568                         if (client->serving_hls_playlist) {
 569                                 construct_hls_playlist(client);
 570                         } else {
 571                                 construct_stream_header(client);
 572                         }
 573                 } else if (error_code == 204) {
 574                         construct_204(client);
 575                 } else {
 576                         construct_error(client, error_code);
 577                 }
 578
 579                 // We've changed states, so fall through.
 580                 assert(client->state == Client::SENDING_SHORT_RESPONSE ||
 581                        client->state == Client::SENDING_HEADER);
 582         }
 583         case Client::SENDING_SHORT_RESPONSE:
 584         case Client::SENDING_HEADER: {
 585 sending_header_or_short_response_again:
 586                 int ret;
 587                 do {
 588                         ret = write(client->sock,
 589                                     client->header_or_short_response->data() + client->header_or_short_response_bytes_sent,
 590                                     client->header_or_short_response->size() - client->header_or_short_response_bytes_sent);
 591                 } while (ret == -1 && errno == EINTR);
 592
 593                 if (ret == -1 && errno == EAGAIN) {
 594                         // We're out of socket space, so now we're at the “low edge” of epoll's
 595                         // edge triggering. epoll will tell us when there is more room, so for now,
 596                         // just return.
 597                         // This is postcondition #4.
 598                         return;
 599                 }
 600
 601                 if (ret == -1) {
 602                         // Error! Postcondition #1.
 603                         log_perror("write");
 604                         close_client(client);
 605                         return;
 606                 }
 607
 608                 client->header_or_short_response_bytes_sent += ret;
 609                 assert(client->header_or_short_response_bytes_sent <= client->header_or_short_response->size());
 610
 611                 if (client->header_or_short_response_bytes_sent < client->header_or_short_response->size()) {
 612                         // We haven't sent all yet. Fine; go another round.
 613                         goto sending_header_or_short_response_again;
 614                 }
 615
 616                 // We're done sending the header or error! Clear it to release some memory.
 617                 client->header_or_short_response = nullptr;
 618                 client->header_or_short_response_holder.clear();
 619                 client->header_or_short_response_ref.reset();
 620
 621                 if (client->state == Client::SENDING_SHORT_RESPONSE) {
 622                         if (more_requests(client)) {
 623                                 // We're done sending the error, but should keep on reading new requests.
 624                                 goto read_request_again;
 625                         } else {
 626                                 // We're done sending the error, so now close.
 627                                 // This is postcondition #1.
 628                                 close_client(client);
 629                         }
 630                         return;
 631                 }
 632
 633                 Stream *stream = client->stream;
 634                 hls_zombies.erase(client->get_hls_zombie_key());
 635                 if (client->stream_pos == Client::STREAM_POS_AT_START) {
 636                         // Start sending from the beginning of the backlog.
 637                         client->stream_pos = min<size_t>(
 638                             stream->bytes_received - stream->backlog_size,
 639                             0);
 640                         client->state = Client::SENDING_DATA;
 641                         goto sending_data;
 642                 } else if (client->stream_pos_end != Client::STREAM_POS_NO_END) {
 643                         // We're sending a fragment, and should have all of it,
 644                         // so start sending right away.
 645                         assert(ssize_t(client->stream_pos) >= 0);
 646                         client->state = Client::SENDING_DATA;
 647                         goto sending_data;
 648                 } else if (stream->prebuffering_bytes == 0) {
 649                         // Start sending from the first keyframe we get. In other
 650                         // words, we won't send any of the backlog, but we'll start
 651                         // sending immediately as we get the next keyframe block.
 652                         // Note that this is functionally identical to the next if branch,
 653                         // except that we save a binary search.
 654                         assert(client->stream_pos == Client::STREAM_POS_AT_END);
 655                         assert(client->stream_pos_end == Client::STREAM_POS_NO_END);
 656                         client->stream_pos = stream->bytes_received;
 657                         client->state = Client::WAITING_FOR_KEYFRAME;
 658                 } else {
 659                         // We're not going to send anything to the client before we have
 660                         // N bytes. However, this wait might be boring; we can just as well
 661                         // use it to send older data if we have it. We use lower_bound()
 662                         // so that we are conservative and never add extra latency over just
 663                         // waiting (assuming CBR or nearly so); otherwise, we could want e.g.
 664                         // 100 kB prebuffer but end up sending a 10 MB GOP.
 665                         assert(client->stream_pos == Client::STREAM_POS_AT_END);
 666                         assert(client->stream_pos_end == Client::STREAM_POS_NO_END);
 667                         deque<uint64_t>::const_iterator starting_point_it =
 668                                 lower_bound(stream->suitable_starting_points.begin(),
 669                                             stream->suitable_starting_points.end(),
 670                                             stream->bytes_received - stream->prebuffering_bytes);
 671                         if (starting_point_it == stream->suitable_starting_points.end()) {
 672                                 // None found. Just put us at the end, and then wait for the
 673                                 // first keyframe to appear.
 674                                 client->stream_pos = stream->bytes_received;
 675                                 client->state = Client::WAITING_FOR_KEYFRAME;
 676                         } else {
 677                                 client->stream_pos = *starting_point_it;
 678                                 client->state = Client::PREBUFFERING;
 679                                 goto prebuffering;
 680                         }
 681                 }
 682                 // Fall through.
 683         }
 684         case Client::WAITING_FOR_KEYFRAME: {
 685                 Stream *stream = client->stream;
 686                 if (stream->suitable_starting_points.empty() ||
 687                     client->stream_pos > stream->suitable_starting_points.back()) {
 688                         // We haven't received a keyframe since this stream started waiting,
 689                         // so keep on waiting for one.
 690                         // This is postcondition #3.
 691                         stream->put_client_to_sleep(client);
 692                         return;
 693                 }
 694                 client->stream_pos = stream->suitable_starting_points.back();
 695                 client->state = Client::PREBUFFERING;
 696                 // Fall through.
 697         }
 698         case Client::PREBUFFERING: {
 699 prebuffering:
 700                 Stream *stream = client->stream;
 701                 size_t bytes_to_send = stream->bytes_received - client->stream_pos;
 702                 assert(bytes_to_send <= stream->backlog_size);
 703                 if (bytes_to_send < stream->prebuffering_bytes) {
 704                         // We don't have enough bytes buffered to start this client yet.
 705                         // This is postcondition #3.
 706                         stream->put_client_to_sleep(client);
 707                         return;
 708                 }
 709                 client->state = Client::SENDING_DATA;
 710                 // Fall through.
 711         }
 712         case Client::SENDING_DATA: {
 713 sending_data:
 714                 skip_lost_data(client);
 715                 Stream *stream = client->stream;
 716
 717 sending_data_again:
 718                 size_t bytes_to_send;
 719                 if (client->stream_pos_end == Client::STREAM_POS_NO_END) {
 720                          bytes_to_send = stream->bytes_received - client->stream_pos;
 721                 } else {
 722                          bytes_to_send = client->stream_pos_end - client->stream_pos;
 723                 }
 724                 assert(bytes_to_send <= stream->backlog_size);
 725                 if (bytes_to_send == 0) {
 726                         if (client->stream_pos == client->stream_pos_end) {  // We have a definite end, and we're at it.
 727                                 // Add (or overwrite) a HLS zombie.
 728                                 timespec now;
 729                                 if (clock_gettime(CLOCK_MONOTONIC_COARSE, &now) == -1) {
 730                                         log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
 731                                 } else {
 732                                         HLSZombie zombie;
 733                                         zombie.remote_addr = client->remote_addr;
 734                                         zombie.referer = client->referer;
 735                                         zombie.user_agent = client->user_agent;
 736                                         zombie.url = client->stream->url + "?frag=<idle>";
 737                                         zombie.expires = now;
 738                                         zombie.expires.tv_sec += client->stream->hls_frag_duration * 3;
 739                                         hls_zombies[client->get_hls_zombie_key()] = move(zombie);
 740                                 }
 741                                 if (more_requests(client)) {
 742                                         // We're done sending the fragment, but should keep on reading new requests.
 743                                         goto read_request_again;
 744                                 } else {
 745                                         // We're done sending the fragment, so now close.
 746                                         // This is postcondition #1.
 747                                         close_client(client);
 748                                 }
 749                         }
 750                         return;
 751                 }
 752
 753                 // See if we need to split across the circular buffer.
 754                 bool more_data = false;
 755                 if ((client->stream_pos % stream->backlog_size) + bytes_to_send > stream->backlog_size) {
 756                         bytes_to_send = stream->backlog_size - (client->stream_pos % stream->backlog_size);
 757                         more_data = true;
 758                 }
 759
 760                 ssize_t ret;
 761                 do {
 762                         off_t offset = client->stream_pos % stream->backlog_size;
 763                         ret = sendfile(client->sock, stream->data_fd, &offset, bytes_to_send);
 764                 } while (ret == -1 && errno == EINTR);
 765
 766                 if (ret == -1 && errno == EAGAIN) {
 767                         // We're out of socket space, so return; epoll will wake us up
 768                         // when there is more room.
 769                         // This is postcondition #4.
 770                         return;
 771                 }
 772                 if (ret == -1) {
 773                         // Error, close; postcondition #1.
 774                         log_perror("sendfile");
 775                         close_client(client);
 776                         return;
 777                 }
 778                 client->stream_pos += ret;
 779                 client->bytes_sent += ret;
 780
 781                 assert(client->stream_pos_end == Client::STREAM_POS_NO_END || client->stream_pos <= client->stream_pos_end);
 782                 if (client->stream_pos == client->stream_pos_end) {
 783                         goto sending_data_again;  // Will see that bytes_to_send == 0 and end.
 784                 } else if (client->stream_pos == stream->bytes_received) {
 785                         // We don't have any more data for this client, so put it to sleep.
 786                         // This is postcondition #3.
 787                         stream->put_client_to_sleep(client);
 788                 } else if (more_data && size_t(ret) == bytes_to_send) {
 789                         goto sending_data_again;
 790                 }
 791                 // We'll also get here for postcondition #4 (similar to the EAGAIN path above).
 792                 break;
 793         }
 794         default:
 795                 assert(false);
 796         }
 797 }
 798
 799 namespace {
 800
 801 void flush_pending_data(int sock)
 802 {
 803         // Flush pending data, which would otherwise wait for the 200ms TCP_CORK timer
 804         // to elapsed; does not cancel out TCP_CORK (since that still takes priority),
 805         // but does a one-off flush.
 806         int one = 1;
 807         if (setsockopt(sock, SOL_TCP, TCP_NODELAY, &one, sizeof(one)) == -1) {
 808                 log_perror("setsockopt(TCP_NODELAY)");
 809                 // Can still continue.
 810         }
 811 }
 812
 813 }  // namespace
 814
 815 bool Server::send_pending_tls_data(Client *client)
 816 {
 817         // See if there's data from the TLS library to write.
 818         if (client->tls_data_to_send == nullptr) {
 819                 client->tls_data_to_send = tls_get_write_buffer(client->tls_context, &client->tls_data_left_to_send);
 820                 if (client->tls_data_to_send == nullptr) {
 821                         // Really no data to send.
 822                         return false;
 823                 }
 824         }
 825
 826 send_data_again:
 827         int ret;
 828         do {
 829                 ret = write(client->sock, client->tls_data_to_send, client->tls_data_left_to_send);
 830         } while (ret == -1 && errno == EINTR);
 831         assert(ret < 0 || size_t(ret) <= client->tls_data_left_to_send);
 832
 833         if (ret == -1 && errno == EAGAIN) {
 834                 // We're out of socket space, so now we're at the “low edge” of epoll's
 835                 // edge triggering. epoll will tell us when there is more room, so for now,
 836                 // just return.
 837                 // This is postcondition #4.
 838                 return true;
 839         }
 840         if (ret == -1) {
 841                 // Error! Postcondition #1.
 842                 log_perror("write");
 843                 close_client(client);
 844                 return true;
 845         }
 846         if (ret > 0 && size_t(ret) == client->tls_data_left_to_send) {
 847                 // All data has been sent, so we don't need to go to sleep
 848                 // (although we are likely to do so immediately afterwards,
 849                 // due to lack of client data).
 850                 tls_buffer_clear(client->tls_context);
 851                 client->tls_data_to_send = nullptr;
 852
 853                 // Flush the data we just wrote, since the client probably
 854                 // is waiting for it.
 855                 flush_pending_data(client->sock);
 856                 return false;
 857         }
 858
 859         // More data to send, so try again.
 860         client->tls_data_to_send += ret;
 861         client->tls_data_left_to_send -= ret;
 862         goto send_data_again;
 863 }
 864
 865 int Server::read_plain_data(Client *client, char *buf, size_t max_size)
 866 {
 867         int ret;
 868         do {
 869                 ret = read(client->sock, buf, max_size);
 870         } while (ret == -1 && errno == EINTR);
 871
 872         if (ret == -1 && errno == EAGAIN) {
 873                 // No more data right now. Nothing to do.
 874                 // This is postcondition #2.
 875                 return -1;
 876         }
 877         if (ret == -1) {
 878                 log_perror("read");
 879                 close_client(client);
 880                 return -1;
 881         }
 882         if (ret == 0) {
 883                 // OK, the socket is closed.
 884                 close_client(client);
 885                 return -1;
 886         }
 887
 888         return ret;
 889 }
 890
 891 int Server::read_tls_data(Client *client, char *buf, size_t max_size)
 892 {
 893 read_again:
 894         assert(!client->in_ktls_mode);
 895
 896         int ret;
 897         do {
 898                 ret = read(client->sock, buf, max_size);
 899         } while (ret == -1 && errno == EINTR);
 900
 901         if (ret == -1 && errno == EAGAIN) {
 902                 // No more data right now. Nothing to do.
 903                 // This is postcondition #2.
 904                 return -1;
 905         }
 906         if (ret == -1) {
 907                 log_perror("read");
 908                 close_client(client);
 909                 return -1;
 910         }
 911         if (ret == 0) {
 912                 // OK, the socket is closed.
 913                 close_client(client);
 914                 return -1;
 915         }
 916
 917         // Give it to the TLS library.
 918         int err = tls_consume_stream(client->tls_context, reinterpret_cast<const unsigned char *>(buf), ret, nullptr);
 919         if (err < 0) {
 920                 log_tls_error("tls_consume_stream", err);
 921                 close_client(client);
 922                 return -1;
 923         }
 924         if (err == 0) {
 925                 // Not consumed any data. See if we can read more.
 926                 goto read_again;
 927         }
 928
 929         // Read any decrypted data available for us. (We can reuse buf, since it's free now.)
 930         ret = tls_read(client->tls_context, reinterpret_cast<unsigned char *>(buf), max_size);
 931         if (ret == 0) {
 932                 // No decrypted data for us yet, but there might be some more handshaking
 933                 // to send. Do that if needed, then look for more data.
 934                 if (send_pending_tls_data(client)) {
 935                         // send_pending_tls_data() hit postconditions #1 or #4.
 936                         return -1;
 937                 }
 938                 goto read_again;
 939         }
 940         if (ret < 0) {
 941                 log_tls_error("tls_read", ret);
 942                 close_client(client);
 943                 return -1;
 944         }
 945
 946         if (tls_established(client->tls_context)) {
 947                 // We're ready to enter kTLS mode, unless we still have some
 948                 // handshake data to send (which then must be sent as non-kTLS).
 949                 if (send_pending_tls_data(client)) {
 950                         // send_pending_tls_data() hit postconditions #1 or #4.
 951                         return -1;
 952                 }
 953                 int err = tls_make_ktls(client->tls_context, client->sock);  // Don't overwrite ret.
 954                 if (err < 0) {
 955                         log_tls_error("tls_make_ktls", ret);
 956                         close_client(client);
 957                         return -1;
 958                 }
 959                 client->in_ktls_mode = true;
 960         }
 961
 962         assert(ret > 0);
 963         return ret;
 964 }
 965
 966 // See if there's some data we've lost. Ideally, we should drop to a block boundary,
 967 // but resync will be the mux's problem.
 968 void Server::skip_lost_data(Client *client)
 969 {
 970         Stream *stream = client->stream;
 971         if (stream == nullptr) {
 972                 return;
 973         }
 974         size_t bytes_to_send = stream->bytes_received - client->stream_pos;
 975         if (bytes_to_send > stream->backlog_size) {
 976                 size_t bytes_lost = bytes_to_send - stream->backlog_size;
 977                 client->bytes_lost += bytes_lost;
 978                 ++client->num_loss_events;
 979                 if (!client->close_after_response) {
 980                         assert(client->stream_pos_end != Client::STREAM_POS_NO_END);
 981
 982                         // We've already sent a Content-Length, so we can't just skip data.
 983                         // Close the connection immediately and hope the other side
 984                         // is able to figure out that there was an error and it needs to skip.
 985                         client->close_after_response = true;
 986                         client->stream_pos = client->stream_pos_end;
 987                 } else {
 988                         client->stream_pos = stream->bytes_received - stream->backlog_size;
 989                 }
 990         }
 991 }
 992
 993 int Server::parse_request(Client *client)
 994 {
 995         vector<string> lines = split_lines(client->request);
 996         client->request.clear();
 997         if (lines.empty()) {
 998                 return 400;  // Bad request (empty).
 999         }
1000
1001         // Parse the headers, for logging purposes.
1002         HTTPHeaderMultimap headers = extract_headers(lines, client->remote_addr);
1003         const auto referer_it = headers.find("Referer");
1004         if (referer_it != headers.end()) {
1005                 client->referer = referer_it->second;
1006         }
1007         const auto user_agent_it = headers.find("User-Agent");
1008         if (user_agent_it != headers.end()) {
1009                 client->user_agent = user_agent_it->second;
1010         }
1011         const auto x_playback_session_id_it = headers.find("X-Playback-Session-Id");
1012         if (x_playback_session_id_it != headers.end()) {
1013                 client->x_playback_session_id = x_playback_session_id_it->second;
1014         } else {
1015                 client->x_playback_session_id.clear();
1016         }
1017
1018         vector<string> request_tokens = split_tokens(lines[0]);
1019         if (request_tokens.size() < 3) {
1020                 return 400;  // Bad request (empty).
1021         }
1022         if (request_tokens[0] != "GET") {
1023                 return 400;  // Should maybe be 405 instead?
1024         }
1025
1026         string url = request_tokens[1];
1027         client->url = url;
1028         if (url.size() > 8 && url.find("?backlog") == url.size() - 8) {
1029                 client->stream_pos = Client::STREAM_POS_AT_START;
1030                 url = url.substr(0, url.size() - 8);
1031         } else {
1032                 size_t pos = url.find("?frag=");
1033                 if (pos != string::npos) {
1034                         // Parse an endpoint of the type /stream.mp4?frag=1234-5678.
1035                         const char *ptr = url.c_str() + pos + 6;
1036
1037                         // "?frag=header" is special.
1038                         if (strcmp(ptr, "header") == 0) {
1039                                 client->stream_pos = Client::STREAM_POS_HEADER_ONLY;
1040                                 client->stream_pos_end = -1;
1041                         } else {
1042                                 char *endptr;
1043                                 long long frag_start = strtol(ptr, &endptr, 10);
1044                                 if (ptr == endptr || frag_start < 0 || frag_start == LLONG_MAX) {
1045                                         return 400;  // Bad request.
1046                                 }
1047                                 if (*endptr != '-') {
1048                                         return 400;  // Bad request.
1049                                 }
1050                                 ptr = endptr + 1;
1051
1052                                 long long frag_end = strtol(ptr, &endptr, 10);
1053                                 if (ptr == endptr || frag_end < frag_start || frag_end == LLONG_MAX) {
1054                                         return 400;  // Bad request.
1055                                 }
1056
1057                                 if (*endptr != '\0') {
1058                                         return 400;  // Bad request.
1059                                 }
1060
1061                                 client->stream_pos = frag_start;
1062                                 client->stream_pos_end = frag_end;
1063                         }
1064                         url = url.substr(0, pos);
1065                 } else {
1066                         client->stream_pos = -1;
1067                         client->stream_pos_end = -1;
1068                 }
1069         }
1070
1071         // Figure out if we're supposed to close the socket after we've delivered the response.
1072         string protocol = request_tokens[2];
1073         if (protocol.find("HTTP/") != 0) {
1074                 return 400;  // Bad request.
1075         }
1076         client->close_after_response = false;
1077         client->http_11 = true;
1078         if (protocol == "HTTP/1.0") {
1079                 // No persistent connections.
1080                 client->close_after_response = true;
1081                 client->http_11 = false;
1082         } else {
1083                 const auto connection_it = headers.find("Connection");
1084                 if (connection_it != headers.end() && connection_it->second == "close") {
1085                         client->close_after_response = true;
1086                 }
1087         }
1088
1089         const auto stream_url_map_it = stream_url_map.find(url);
1090         if (stream_url_map_it != stream_url_map.end()) {
1091                 // Serve a regular stream..
1092                 client->stream = streams[stream_url_map_it->second].get();
1093                 client->serving_hls_playlist = false;
1094         } else {
1095                 const auto stream_hls_url_map_it = stream_hls_url_map.find(url);
1096                 if (stream_hls_url_map_it != stream_hls_url_map.end()) {
1097                         // Serve HLS playlist.
1098                         client->stream = streams[stream_hls_url_map_it->second].get();
1099                         client->serving_hls_playlist = true;
1100                 } else {
1101                         const auto ping_url_map_it = ping_url_map.find(url);
1102                         if (ping_url_map_it == ping_url_map.end()) {
1103                                 return 404;  // Not found.
1104                         } else {
1105                                 // Serve a ping (204 no error).
1106                                 return 204;
1107                         }
1108                 }
1109         }
1110
1111         Stream *stream = client->stream;
1112
1113         if (client->serving_hls_playlist) {
1114                 if (stream->encoding == Stream::STREAM_ENCODING_METACUBE) {
1115                         // This doesn't make any sense, and is hard to implement, too.
1116                         return 404;
1117                 } else {
1118                         return 200;
1119                 }
1120         }
1121
1122         if (client->stream_pos_end == Client::STREAM_POS_NO_END) {
1123                 if (stream->unavailable) {
1124                         return 503;  // Service unavailable.
1125                 }
1126
1127                 // This stream won't end, so we don't have a content-length,
1128                 // and can just as well tell the client it's Connection: close
1129                 // (otherwise, we'd have to implement chunking TE for no good reason).
1130                 client->close_after_response = true;
1131         } else {
1132                 if (stream->encoding == Stream::STREAM_ENCODING_METACUBE) {
1133                         // This doesn't make any sense, and is hard to implement, too.
1134                         return 416;  // Range not satisfiable.
1135                 }
1136
1137                 // Check that we have the requested fragment in our backlog.
1138                 size_t buffer_end = stream->bytes_received;
1139                 size_t buffer_start = (buffer_end <= stream->backlog_size) ? 0 : buffer_end - stream->backlog_size;
1140
1141                 if (client->stream_pos_end > buffer_end ||
1142                     client->stream_pos < buffer_start) {
1143                         return 416;  // Range not satisfiable.
1144                 }
1145         }
1146
1147         client->stream = stream;
1148         if (setsockopt(client->sock, SOL_SOCKET, SO_MAX_PACING_RATE, &client->stream->pacing_rate, sizeof(client->stream->pacing_rate)) == -1) {
1149                 if (client->stream->pacing_rate != ~0U) {
1150                         log_perror("setsockopt(SO_MAX_PACING_RATE)");
1151                 }
1152         }
1153         client->request.clear();
1154
1155         return 200;  // OK!
1156 }
1157
1158 void Server::construct_stream_header(Client *client)
1159 {
1160         Stream *stream = client->stream;
1161         string response = stream->http_header;
1162         if (client->stream_pos == Client::STREAM_POS_HEADER_ONLY) {
1163                 char buf[64];
1164                 snprintf(buf, sizeof(buf), "Content-Length: %zu\r\n", stream->stream_header.size());
1165                 response.append(buf);
1166         } else if (client->stream_pos_end != Client::STREAM_POS_NO_END) {
1167                 char buf[64];
1168                 snprintf(buf, sizeof(buf), "Content-Length: %" PRIu64 "\r\n", client->stream_pos_end - client->stream_pos);
1169                 response.append(buf);
1170         }
1171         if (client->http_11) {
1172                 assert(response.find("HTTP/1.0") == 0);
1173                 response[7] = '1';  // Change to HTTP/1.1.
1174                 if (client->close_after_response) {
1175                         response.append("Connection: close\r\n");
1176                 }
1177         } else {
1178                 assert(client->close_after_response);
1179         }
1180         if (!stream->allow_origin.empty()) {
1181                 response.append("Access-Control-Allow-Origin: ");
1182                 response.append(stream->allow_origin);
1183                 response.append("\r\n");
1184         }
1185         if (stream->encoding == Stream::STREAM_ENCODING_RAW) {
1186                 response.append("\r\n");
1187         } else if (stream->encoding == Stream::STREAM_ENCODING_METACUBE) {
1188                 response.append("Content-Encoding: metacube\r\n\r\n");
1189                 if (!stream->stream_header.empty()) {
1190                         metacube2_block_header hdr;
1191                         memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
1192                         hdr.size = htonl(stream->stream_header.size());
1193                         hdr.flags = htons(METACUBE_FLAGS_HEADER);
1194                         hdr.csum = htons(metacube2_compute_crc(&hdr));
1195                         response.append(string(reinterpret_cast<char *>(&hdr), sizeof(hdr)));
1196                 }
1197         } else {
1198                 assert(false);
1199         }
1200         if (client->stream_pos == Client::STREAM_POS_HEADER_ONLY) {
1201                 client->state = Client::SENDING_SHORT_RESPONSE;
1202                 response.append(stream->stream_header);
1203         } else {
1204                 client->state = Client::SENDING_HEADER;
1205                 if (client->stream_pos_end == Client::STREAM_POS_NO_END) {  // Fragments don't contain stream headers.
1206                         response.append(stream->stream_header);
1207                 }
1208         }
1209
1210         client->header_or_short_response_holder = move(response);
1211         client->header_or_short_response = &client->header_or_short_response_holder;
1212
1213         // Switch states.
1214         change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
1215 }
1216
1217 void Server::construct_error(Client *client, int error_code)
1218 {
1219         char error[256];
1220         if (client->http_11 && client->close_after_response) {
1221                 snprintf(error, sizeof(error),
1222                         "HTTP/1.1 %d Error\r\nContent-Type: text/plain\r\nConnection: close\r\n\r\nSomething went wrong. Sorry.\r\n",
1223                         error_code);
1224         } else {
1225                 snprintf(error, sizeof(error),
1226                         "HTTP/1.%d %d Error\r\nContent-Type: text/plain\r\nContent-Length: 30\r\n\r\nSomething went wrong. Sorry.\r\n",
1227                         client->http_11, error_code);
1228         }
1229         client->header_or_short_response_holder = error;
1230         client->header_or_short_response = &client->header_or_short_response_holder;
1231
1232         // Switch states.
1233         client->state = Client::SENDING_SHORT_RESPONSE;
1234         change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
1235 }
1236
1237 void Server::construct_hls_playlist(Client *client)
1238 {
1239         Stream *stream = client->stream;
1240         shared_ptr<const string> *cache;
1241         if (client->http_11) {
1242                 if (client->close_after_response) {
1243                         cache = &stream->hls_playlist_http11_close;
1244                 } else {
1245                         cache = &stream->hls_playlist_http11_persistent;
1246                 }
1247         } else {
1248                 assert(client->close_after_response);
1249                 cache = &stream->hls_playlist_http10;
1250         }
1251
1252         if (*cache == nullptr) {
1253                 *cache = stream->generate_hls_playlist(client->http_11, client->close_after_response);
1254         }
1255         client->header_or_short_response_ref = *cache;
1256         client->header_or_short_response = cache->get();
1257
1258         // Switch states.
1259         client->state = Client::SENDING_SHORT_RESPONSE;
1260         change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
1261 }
1262
1263 void Server::construct_204(Client *client)
1264 {
1265         const auto ping_url_map_it = ping_url_map.find(client->url);
1266         assert(ping_url_map_it != ping_url_map.end());
1267
1268         string response;
1269         if (client->http_11) {
1270                 response = "HTTP/1.1 204 No Content\r\n";
1271                 if (client->close_after_response) {
1272                         response.append("Connection: close\r\n");
1273                 }
1274         } else {
1275                 response = "HTTP/1.0 204 No Content\r\n";
1276                 assert(client->close_after_response);
1277         }
1278         if (!ping_url_map_it->second.empty()) {
1279                 response.append("Access-Control-Allow-Origin: ");
1280                 response.append(ping_url_map_it->second);
1281                 response.append("\r\n");
1282         }
1283         response.append("\r\n");
1284
1285         client->header_or_short_response_holder = move(response);
1286         client->header_or_short_response = &client->header_or_short_response_holder;
1287
1288         // Switch states.
1289         client->state = Client::SENDING_SHORT_RESPONSE;
1290         change_epoll_events(client, EPOLLOUT | EPOLLET | EPOLLRDHUP);
1291 }
1292
1293 namespace {
1294
1295 template<class T>
1296 void delete_from(vector<T> *v, T elem)
1297 {
1298         typename vector<T>::iterator new_end = remove(v->begin(), v->end(), elem);
1299         v->erase(new_end, v->end());
1300 }
1301
1302 void send_ktls_close(int sock)
1303 {
1304         uint8_t record_type = 21;  // Alert.
1305         uint8_t body[] = {
1306                 1,   // Warning level (but still fatal!).
1307                 0,   // close_notify.
1308         };
1309
1310         int cmsg_len = sizeof(record_type);
1311         char buf[CMSG_SPACE(cmsg_len)];
1312
1313         msghdr msg = {0};
1314         msg.msg_control = buf;
1315         msg.msg_controllen = sizeof(buf);
1316         cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
1317         cmsg->cmsg_level = SOL_TLS;
1318         cmsg->cmsg_type = TLS_SET_RECORD_TYPE;
1319         cmsg->cmsg_len = CMSG_LEN(cmsg_len);
1320         *CMSG_DATA(cmsg) = record_type;
1321         msg.msg_controllen = cmsg->cmsg_len;
1322
1323         iovec msg_iov;
1324         msg_iov.iov_base = body;
1325         msg_iov.iov_len = sizeof(body);
1326         msg.msg_iov = &msg_iov;
1327         msg.msg_iovlen = 1;
1328
1329         int err;
1330         do {
1331                 err = sendmsg(sock, &msg, 0);
1332         } while (err == -1 && errno == EINTR);  // Ignore all other errors.
1333 }
1334
1335 }  // namespace
1336
1337 void Server::close_client(Client *client)
1338 {
1339         if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, client->sock, nullptr) == -1) {
1340                 log_perror("epoll_ctl(EPOLL_CTL_DEL)");
1341                 exit(1);
1342         }
1343
1344         // This client could be sleeping, so we'll need to fix that. (Argh, O(n).)
1345         if (client->stream != nullptr) {
1346                 delete_from(&client->stream->sleeping_clients, client);
1347                 delete_from(&client->stream->to_process, client);
1348         }
1349
1350         if (client->tls_context) {
1351                 if (client->in_ktls_mode) {
1352                         // Keep GnuTLS happy.
1353                         send_ktls_close(client->sock);
1354                 }
1355                 tls_destroy_context(client->tls_context);
1356         }
1357
1358         // Log to access_log.
1359         access_log->write(client->get_stats());
1360
1361         // Bye-bye!
1362         safe_close(client->sock);
1363
1364         clients.erase(client->sock);
1365 }
1366
1367 void Server::change_epoll_events(Client *client, uint32_t events)
1368 {
1369         epoll_event ev;
1370         ev.events = events;
1371         ev.data.ptr = client;
1372
1373         if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
1374                 log_perror("epoll_ctl(EPOLL_CTL_MOD)");
1375                 exit(1);
1376         }
1377 }
1378
1379 bool Server::more_requests(Client *client)
1380 {
1381         if (client->close_after_response) {
1382                 return false;
1383         }
1384
1385         // Log to access_log.
1386         access_log->write(client->get_stats());
1387
1388         flush_pending_data(client->sock);
1389
1390         // Switch states and reset the parsers. We don't reset statistics.
1391         client->state = Client::READING_REQUEST;
1392         client->url.clear();
1393         client->stream = NULL;
1394         client->header_or_short_response = nullptr;
1395         client->header_or_short_response_holder.clear();
1396         client->header_or_short_response_ref.reset();
1397         client->header_or_short_response_bytes_sent = 0;
1398         client->bytes_sent = 0;
1399         start_client_timeout_timer(client);
1400
1401         change_epoll_events(client, EPOLLIN | EPOLLET | EPOLLRDHUP);  // No TLS handshake, so no EPOLLOUT needed.
1402
1403         return true;
1404 }
1405
1406 void Server::process_queued_data()
1407 {
1408         {
1409                 lock_guard<mutex> lock(queued_clients_mutex);
1410
1411                 for (const pair<int, Acceptor *> &id_and_acceptor : queued_add_clients) {
1412                         add_client(id_and_acceptor.first, id_and_acceptor.second);
1413                 }
1414                 queued_add_clients.clear();
1415         }
1416
1417         for (unique_ptr<Stream> &stream : streams) {
1418                 stream->process_queued_data();
1419         }
1420 }