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

   1 #include <assert.h>
   2 #include <errno.h>
   3 #include <getopt.h>
   4 #include <limits.h>
   5 #include <signal.h>
   6 #include <stddef.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <sys/time.h>
  11 #include <sys/wait.h>
  12 #include <systemd/sd-daemon.h>
  13 #include <unistd.h>
  14 #include <algorithm>
  15 #include <map>
  16 #include <set>
  17 #include <string>
  18 #include <unordered_map>
  19 #include <utility>
  20 #include <vector>
  21
  22 #include "tlse.h"
  23
  24 #include "acceptor.h"
  25 #include "accesslog.h"
  26 #include "config.h"
  27 #include "input.h"
  28 #include "input_stats.h"
  29 #include "log.h"
  30 #include "sa_compare.h"
  31 #include "serverpool.h"
  32 #include "state.pb.h"
  33 #include "stats.h"
  34 #include "stream.h"
  35 #include "util.h"
  36 #include "version.h"
  37
  38 using namespace std;
  39
  40 AccessLogThread *access_log = nullptr;
  41 ServerPool *servers = nullptr;
  42 volatile bool hupped = false;
  43 volatile bool stopped = false;
  44
  45 typedef pair<string, Input::Encoding> InputKey;
  46
  47 namespace {
  48
  49 struct OrderByConnectionTime {
  50         bool operator() (const ClientProto &a, const ClientProto &b) const {
  51                 if (a.connect_time_sec() != b.connect_time_sec())
  52                         return a.connect_time_sec() < b.connect_time_sec();
  53                 return a.connect_time_nsec() < b.connect_time_nsec();
  54         }
  55 };
  56
  57 // An arbitrary ordering.
  58 struct AcceptorConfigCompare {
  59         bool operator() (const AcceptorConfig &a, const AcceptorConfig &b) const {
  60                 int cmp = a.certificate_chain.compare(b.certificate_chain);
  61                 if (cmp != 0) {
  62                         return cmp < 0;
  63                 }
  64
  65                 cmp = a.private_key.compare(b.private_key);
  66                 if (cmp != 0) {
  67                         return cmp < 0;
  68                 }
  69
  70                 return Sockaddr6Compare()(a.addr, b.addr);
  71         }
  72 };
  73
  74 }  // namespace
  75
  76 struct InputWithRefcount {
  77         Input *input;
  78         int refcount;
  79 };
  80
  81 void hup(int signum)
  82 {
  83         hupped = true;
  84         if (signum == SIGINT) {
  85                 stopped = true;
  86         }
  87 }
  88
  89 void do_nothing(int signum)
  90 {
  91 }
  92
  93 CubemapStateProto collect_state(const timespec &serialize_start,
  94                                 const vector<Acceptor *> acceptors,
  95                                 const multimap<InputKey, InputWithRefcount> inputs,
  96                                 ServerPool *servers)
  97 {
  98         CubemapStateProto state = servers->serialize();  // Fills streams() and clients().
  99         state.set_serialize_start_sec(serialize_start.tv_sec);
 100         state.set_serialize_start_usec(serialize_start.tv_nsec / 1000);
 101
 102         for (Acceptor *acceptor : acceptors) {
 103                 state.add_acceptors()->MergeFrom(acceptor->serialize());
 104         }
 105
 106         for (const auto &key_and_input_with_refcount : inputs) {
 107                 state.add_inputs()->MergeFrom(key_and_input_with_refcount.second.input->serialize());
 108         }
 109
 110         return state;
 111 }
 112
 113 // Find all port statements in the configuration file, and create acceptors for them.
 114 vector<Acceptor *> create_acceptors(
 115         const Config &config,
 116         map<AcceptorConfig, Acceptor *, AcceptorConfigCompare> *deserialized_acceptors)
 117 {
 118         vector<Acceptor *> acceptors;
 119         for (const AcceptorConfig &acceptor_config : config.acceptors) {
 120                 Acceptor *acceptor = nullptr;
 121                 const auto deserialized_acceptor_it = deserialized_acceptors->find(acceptor_config);
 122                 if (deserialized_acceptor_it != deserialized_acceptors->end()) {
 123                         acceptor = deserialized_acceptor_it->second;
 124                         deserialized_acceptors->erase(deserialized_acceptor_it);
 125                 } else {
 126                         int server_sock = create_server_socket(acceptor_config.addr, TCP_SOCKET);
 127                         acceptor = new Acceptor(server_sock, acceptor_config.addr,
 128                                                 acceptor_config.certificate_chain,
 129                                                 acceptor_config.private_key);
 130                 }
 131                 acceptor->run();
 132                 acceptors.push_back(acceptor);
 133         }
 134
 135         // Close all acceptors that are no longer in the configuration file.
 136         for (auto &config_and_acceptor : *deserialized_acceptors) {
 137                 config_and_acceptor.second->close_socket();
 138                 delete config_and_acceptor.second;
 139         }
 140
 141         return acceptors;
 142 }
 143
 144 void create_config_input(const string &src, Input::Encoding encoding, multimap<InputKey, InputWithRefcount> *inputs)
 145 {
 146         if (src.empty()) {
 147                 return;
 148         }
 149         InputKey key(src, encoding);
 150         if (inputs->count(key) != 0) {
 151                 return;
 152         }
 153
 154         InputWithRefcount iwr;
 155         iwr.input = create_input(src, encoding);
 156         if (iwr.input == nullptr) {
 157                 log(ERROR, "did not understand URL '%s' or source encoding was invalid, clients will not get any data.",
 158                         src.c_str());
 159                 return;
 160         }
 161         iwr.refcount = 0;
 162         inputs->insert(make_pair(key, iwr));
 163 }
 164
 165 // Find all streams in the configuration file, and create inputs for them.
 166 void create_config_inputs(const Config &config, multimap<InputKey, InputWithRefcount> *inputs)
 167 {
 168         for (const StreamConfig &stream_config : config.streams) {
 169                 if (stream_config.src == "delete") {
 170                         // Ignored for pre-1.4.0 configuration compatibility.
 171                         continue;
 172                 }
 173                 create_config_input(stream_config.src, Input::Encoding(stream_config.src_encoding), inputs);
 174         }
 175         for (const UDPStreamConfig &udpstream_config : config.udpstreams) {
 176                 create_config_input(udpstream_config.src, Input::INPUT_ENCODING_RAW, inputs);
 177         }
 178 }
 179
 180 void create_streams(const Config &config,
 181                     const set<string> &deserialized_urls,
 182                     multimap<InputKey, InputWithRefcount> *inputs)
 183 {
 184         // HTTP streams.
 185         set<string> expecting_urls = deserialized_urls;
 186         for (const StreamConfig &stream_config : config.streams) {
 187                 int stream_index;
 188
 189                 expecting_urls.erase(stream_config.url);
 190
 191                 if (stream_config.src == "delete") {
 192                         // Ignored for pre-1.4.0 configuration compatibility.
 193                         continue;
 194                 }
 195
 196                 if (deserialized_urls.count(stream_config.url) == 0) {
 197                         stream_index = servers->add_stream(stream_config.url,
 198                                                            stream_config.hls_url,
 199                                                            stream_config.backlog_size,
 200                                                            stream_config.prebuffering_bytes,
 201                                                            Stream::Encoding(stream_config.encoding),
 202                                                            Stream::Encoding(stream_config.src_encoding),
 203                                                            stream_config.hls_frag_duration,
 204                                                            stream_config.hls_backlog_margin,
 205                                                            stream_config.allow_origin);
 206                 } else {
 207                         stream_index = servers->lookup_stream_by_url(stream_config.url);
 208                         assert(stream_index != -1);
 209                         servers->set_backlog_size(stream_index, stream_config.backlog_size);
 210                         if (!stream_config.hls_url.empty()) {
 211                                 servers->register_hls_url(stream_index, stream_config.hls_url);
 212                         }
 213                         servers->set_prebuffering_bytes(stream_index, stream_config.prebuffering_bytes);
 214                         servers->set_encoding(stream_index,
 215                                               Stream::Encoding(stream_config.encoding));
 216                         servers->set_src_encoding(stream_index,
 217                                                   Stream::Encoding(stream_config.src_encoding));
 218                         servers->set_hls_frag_duration(stream_index, stream_config.hls_frag_duration);
 219                         servers->set_hls_backlog_margin(stream_index, stream_config.hls_backlog_margin);
 220                         servers->set_allow_origin(stream_index, stream_config.allow_origin);
 221                 }
 222
 223                 servers->set_pacing_rate(stream_index, stream_config.pacing_rate);
 224
 225                 string src = stream_config.src;
 226                 Input::Encoding src_encoding = Input::Encoding(stream_config.src_encoding);
 227                 if (!src.empty()) {
 228                         const auto input_it = inputs->find(make_pair(src, src_encoding));
 229                         if (input_it != inputs->end()) {
 230                                 input_it->second.input->add_destination(stream_index);
 231                                 ++input_it->second.refcount;
 232                         }
 233                 }
 234         }
 235
 236         // Warn about any streams servers we've lost.
 237         for (const string &url : expecting_urls) {
 238                 log(WARNING, "stream '%s' disappeared from the configuration file. "
 239                              "It will not be deleted, but clients will not get any new inputs. "
 240                              "If you really meant to delete it, set src=delete and reload.",
 241                              url.c_str());
 242         }
 243
 244         // UDP streams.
 245         for (const UDPStreamConfig &udpstream_config : config.udpstreams) {
 246                 int stream_index = servers->add_udpstream(
 247                         udpstream_config.dst,
 248                         udpstream_config.pacing_rate,
 249                         udpstream_config.ttl,
 250                         udpstream_config.multicast_iface_index);
 251
 252                 string src = udpstream_config.src;
 253                 if (!src.empty()) {
 254                         auto input_it = inputs->find(make_pair(src, Input::INPUT_ENCODING_RAW));
 255                         assert(input_it != inputs->end());
 256                         input_it->second.input->add_destination(stream_index);
 257                         ++input_it->second.refcount;
 258                 }
 259         }
 260
 261         // HTTP gen204 endpoints.
 262         for (const Gen204Config &ping_config : config.pings) {
 263                 servers->add_gen204(ping_config.url, ping_config.allow_origin);
 264         }
 265 }
 266
 267 void open_logs(const vector<LogConfig> &log_destinations)
 268 {
 269         for (const LogConfig &log_destination : log_destinations) {
 270                 if (log_destination.type == LogConfig::LOG_TYPE_FILE) {
 271                         add_log_destination_file(log_destination.filename);
 272                 } else if (log_destination.type == LogConfig::LOG_TYPE_CONSOLE) {
 273                         add_log_destination_console();
 274                 } else if (log_destination.type == LogConfig::LOG_TYPE_SYSLOG) {
 275                         add_log_destination_syslog();
 276                 } else {
 277                         assert(false);
 278                 }
 279         }
 280         start_logging();
 281 }
 282
 283 bool dry_run_config(const string &argv0, const string &config_filename)
 284 {
 285         char *argv0_copy = strdup(argv0.c_str());
 286         char *config_filename_copy = strdup(config_filename.c_str());
 287
 288         pid_t pid = fork();
 289         switch (pid) {
 290         case -1:
 291                 log_perror("fork()");
 292                 free(argv0_copy);
 293                 free(config_filename_copy);
 294                 return false;
 295         case 0:
 296                 // Child.
 297                 execlp(argv0_copy, argv0_copy, "--test-config", config_filename_copy, nullptr);
 298                 log_perror(argv0_copy);
 299                 _exit(1);
 300         default:
 301                 // Parent.
 302                 break;
 303         }
 304
 305         free(argv0_copy);
 306         free(config_filename_copy);
 307
 308         int status;
 309         pid_t err;
 310         do {
 311                 err = waitpid(pid, &status, 0);
 312         } while (err == -1 && errno == EINTR);
 313
 314         if (err == -1) {
 315                 log_perror("waitpid()");
 316                 return false;
 317         }
 318
 319         return (WIFEXITED(status) && WEXITSTATUS(status) == 0);
 320 }
 321
 322 void find_all_streams(const Config &config, set<string> *all_urls)
 323 {
 324         for (const StreamConfig &stream_config : config.streams) {
 325                 if (stream_config.src == "delete") {
 326                         log(WARNING, "stream '%s' has src=delete; ignoring it. Since Cubemap 1.4.0, you do not "
 327                                      "need to set src=delete to delete streams anymore; just delete them from "
 328                                      "the configuration file.",
 329                                      stream_config.url.c_str());
 330                 } else {
 331                         all_urls->insert(stream_config.url);
 332                 }
 333         }
 334 }
 335
 336 int main(int argc, char **argv)
 337 {
 338         signal(SIGHUP, hup);
 339         signal(SIGINT, hup);
 340         signal(SIGUSR1, do_nothing);  // Used in internal signalling.
 341         signal(SIGPIPE, SIG_IGN);
 342
 343         tls_init();
 344
 345         // Parse options.
 346         int state_fd = -1;
 347         bool test_config = false;
 348         for ( ;; ) {
 349                 static const option long_options[] = {
 350                         { "state", required_argument, 0, 's' },
 351                         { "test-config", no_argument, 0, 't' },
 352                         { 0, 0, 0, 0 }
 353                 };
 354                 int option_index = 0;
 355                 int c = getopt_long(argc, argv, "s:t", long_options, &option_index);
 356
 357                 if (c == -1) {
 358                         break;
 359                 }
 360                 switch (c) {
 361                 case 's':
 362                         state_fd = atoi(optarg);
 363                         break;
 364                 case 't':
 365                         test_config = true;
 366                         break;
 367                 default:
 368                         fprintf(stderr, "Unknown option '%s'\n", argv[option_index]);
 369                         exit(1);
 370                 }
 371         }
 372
 373         string config_filename = "cubemap.config";
 374         if (optind < argc) {
 375                 config_filename = argv[optind++];
 376         }
 377
 378         // Canonicalize argv[0] and config_filename.
 379         char argv0_canon[PATH_MAX];
 380         char config_filename_canon[PATH_MAX];
 381
 382         if (realpath("/proc/self/exe", argv0_canon) == nullptr) {
 383                 log_perror(argv[0]);
 384                 exit(1);
 385         }
 386         if (realpath(config_filename.c_str(), config_filename_canon) == nullptr) {
 387                 log_perror(config_filename.c_str());
 388                 exit(1);
 389         }
 390
 391         // Now parse the configuration file.
 392         Config config;
 393         if (!parse_config(config_filename_canon, &config)) {
 394                 exit(1);
 395         }
 396         if (test_config) {
 397                 exit(0);
 398         }
 399
 400         // Ideally we'd like to daemonize only when we've started up all threads etc.,
 401         // but daemon() forks, which is not good in multithreaded software, so we'll
 402         // have to do it here.
 403         if (config.daemonize) {
 404                 if (daemon(0, 0) == -1) {
 405                         log_perror("daemon");
 406                         exit(1);
 407                 }
 408         }
 409
 410 start:
 411         // Open logs as soon as possible.
 412         open_logs(config.log_destinations);
 413
 414         log(INFO, "Cubemap " SERVER_VERSION " starting.");
 415         if (config.access_log_file.empty()) {
 416                 // Create a dummy logger.
 417                 access_log = new AccessLogThread();
 418         } else {
 419                 access_log = new AccessLogThread(config.access_log_file);
 420         }
 421         access_log->run();
 422
 423         servers = new ServerPool(config.num_servers);
 424
 425         // Find all the streams that are to be kept.
 426         set<string> all_urls;
 427         find_all_streams(config, &all_urls);
 428
 429         CubemapStateProto loaded_state;
 430         timespec serialize_start;
 431         set<string> deserialized_urls;
 432         map<AcceptorConfig, Acceptor *, AcceptorConfigCompare> deserialized_acceptors;
 433         multimap<InputKey, InputWithRefcount> inputs;  // multimap due to older versions without deduplication.
 434         if (state_fd != -1) {
 435                 log(INFO, "Deserializing state from previous process...");
 436                 string serialized;
 437                 if (!read_tempfile_and_close(state_fd, &serialized)) {
 438                         exit(1);
 439                 }
 440                 if (!loaded_state.ParseFromString(serialized)) {
 441                         log(ERROR, "Failed deserialization of state.");
 442                         exit(1);
 443                 }
 444
 445                 serialize_start.tv_sec = loaded_state.serialize_start_sec();
 446                 serialize_start.tv_nsec = loaded_state.serialize_start_usec() * 1000ull;
 447
 448                 // Deserialize the streams.
 449                 unordered_map<string, string> stream_headers_for_url;  // See below.
 450                 for (const StreamProto &stream : loaded_state.streams()) {
 451                         if (all_urls.count(stream.url()) == 0) {
 452                                 // Delete the stream backlogs.
 453                                 log(INFO, "Deleting stream '%s'.", stream.url().c_str());
 454                                 for (const int fd : stream.data_fds()) {
 455                                         safe_close(fd);
 456                                 }
 457                         } else {
 458                                 vector<int> data_fds;
 459                                 for (const int fd : stream.data_fds()) {
 460                                         data_fds.push_back(fd);
 461                                 }
 462
 463                                 servers->add_stream_from_serialized(stream, data_fds);
 464                                 deserialized_urls.insert(stream.url());
 465
 466                                 stream_headers_for_url.insert(make_pair(stream.url(), stream.stream_header()));
 467                         }
 468                 }
 469
 470                 // Deserialize the inputs. Note that we don't actually add them to any stream yet.
 471                 for (const InputProto &serialized_input : loaded_state.inputs()) {
 472                         InputWithRefcount iwr;
 473                         iwr.input = create_input(serialized_input);
 474                         iwr.refcount = 0;
 475
 476                         Input::Encoding src_encoding = serialized_input.is_metacube_encoded() ?
 477                                 Input::INPUT_ENCODING_METACUBE :
 478                                 Input::INPUT_ENCODING_RAW;
 479                         InputKey key(serialized_input.url(), src_encoding);
 480                         inputs.insert(make_pair(key, iwr));
 481                 }
 482
 483                 // Deserialize the acceptors.
 484                 for (const AcceptorProto &serialized_acceptor : loaded_state.acceptors()) {
 485                         AcceptorConfig config;
 486                         config.addr = extract_address_from_acceptor_proto(serialized_acceptor);
 487                         config.certificate_chain = serialized_acceptor.certificate_chain();
 488                         config.private_key = serialized_acceptor.private_key();
 489                         deserialized_acceptors.insert(make_pair(
 490                                 config,
 491                                 new Acceptor(serialized_acceptor)));
 492                 }
 493
 494                 log(INFO, "Deserialization done.");
 495         }
 496
 497         // Add any new inputs coming from the config.
 498         create_config_inputs(config, &inputs);
 499
 500         // Find all streams in the configuration file, create them, and connect to the inputs.
 501         create_streams(config, deserialized_urls, &inputs);
 502         vector<Acceptor *> acceptors = create_acceptors(config, &deserialized_acceptors);
 503
 504         // Make all the servers create TLS contexts for every TLS keypair we have.
 505         for (Acceptor *acceptor : acceptors) {
 506                 if (acceptor->is_tls()) {
 507                         servers->create_tls_context_for_acceptor(acceptor);
 508                 }
 509         }
 510
 511         // Allocate strings for the short responses.
 512         vector<shared_ptr<const string>> short_response_pool;
 513         for (const ShortResponsePool &str : loaded_state.short_response_pool()) {
 514                 short_response_pool.emplace_back(new string(str.header_or_short_response()));
 515         }
 516
 517         // Put back the existing clients. It doesn't matter which server we
 518         // allocate them to, so just do round-robin. However, we need to sort them
 519         // by connection time first, since add_client_serialized() expects that.
 520         sort(loaded_state.mutable_clients()->begin(),
 521              loaded_state.mutable_clients()->end(),
 522              OrderByConnectionTime());
 523         for (int i = 0; i < loaded_state.clients_size(); ++i) {
 524                 if (!loaded_state.clients(i).url().empty() &&
 525                     all_urls.count(loaded_state.clients(i).url()) == 0) {
 526                         // Belongs to a dead stream (not keepalive), so we just have to close.
 527                         safe_close(loaded_state.clients(i).sock());
 528                 } else {
 529                         servers->add_client_from_serialized(loaded_state.clients(i), short_response_pool);
 530                 }
 531         }
 532
 533         short_response_pool.clear();  // No longer needed; the clients have their own refcounts now.
 534
 535         // Put back the HLS zombies. There's no really good allocation here
 536         // except round-robin; it would be marginally more efficient to match it
 537         // to the client (since that would have them deleted immediately when
 538         // the client requests the next fragment, instead of being later weeded
 539         // out during statistics collection), but it's not a big deal.
 540         for (const HLSZombieProto &zombie_proto : loaded_state.hls_zombies()) {
 541                 servers->add_hls_zombie_from_serialized(zombie_proto);
 542         }
 543
 544         servers->run();
 545
 546         // Now delete all inputs that are longer in use, and start the others.
 547         for (auto input_it = inputs.begin(); input_it != inputs.end(); ) {
 548                 if (input_it->second.refcount == 0) {
 549                         if (input_it->first.second == Input::INPUT_ENCODING_RAW) {
 550                                 log(WARNING, "Raw input '%s' no longer in use, closing.",
 551                                     input_it->first.first.c_str());
 552                         } else {
 553                                 assert(input_it->first.second == Input::INPUT_ENCODING_METACUBE);
 554                                 log(WARNING, "Metacube input '%s' no longer in use, closing.",
 555                                     input_it->first.first.c_str());
 556                         }
 557                         input_it->second.input->close_socket();
 558                         delete input_it->second.input;
 559                         inputs.erase(input_it++);
 560                 } else {
 561                         input_it->second.input->run();
 562                         ++input_it;
 563                 }
 564         }
 565
 566         // Start writing statistics.
 567         unique_ptr<StatsThread> stats_thread;
 568         if (!config.stats_file.empty()) {
 569                 stats_thread.reset(new StatsThread(config.stats_file, config.stats_interval));
 570                 stats_thread->run();
 571         }
 572
 573         unique_ptr<InputStatsThread> input_stats_thread;
 574         if (!config.input_stats_file.empty()) {
 575                 vector<Input*> inputs_no_refcount;
 576                 for (const auto &key_and_input_with_refcount : inputs) {
 577                         inputs_no_refcount.push_back(key_and_input_with_refcount.second.input);
 578                 }
 579
 580                 input_stats_thread.reset(new InputStatsThread(config.input_stats_file, config.input_stats_interval, inputs_no_refcount));
 581                 input_stats_thread->run();
 582         }
 583
 584         timespec server_start;
 585         int err = clock_gettime(CLOCK_MONOTONIC, &server_start);
 586         assert(err != -1);
 587         if (state_fd != -1) {
 588                 // Measure time from we started deserializing (below) to now, when basically everything
 589                 // is up and running. This is, in other words, a conservative estimate of how long our
 590                 // “glitch” period was, not counting of course reconnects if the configuration changed.
 591                 double glitch_time = server_start.tv_sec - serialize_start.tv_sec +
 592                         1e-9 * (server_start.tv_nsec - serialize_start.tv_nsec);
 593                 log(INFO, "Re-exec happened in approx. %.0f ms.", glitch_time * 1000.0);
 594         }
 595
 596         sd_notify(0, "READY=1");
 597
 598         while (!hupped) {
 599                 usleep(100000);
 600         }
 601
 602         if (stopped) {
 603                 sd_notify(0, "STOPPING=1");
 604         } else {
 605                 sd_notify(0, "RELOADING=1");
 606         }
 607
 608         // OK, we've been HUPed. Time to shut down everything, serialize, and re-exec.
 609         err = clock_gettime(CLOCK_MONOTONIC, &serialize_start);
 610         assert(err != -1);
 611
 612         if (input_stats_thread != nullptr) {
 613                 input_stats_thread->stop();
 614                 input_stats_thread.reset();
 615         }
 616         if (stats_thread != nullptr) {
 617                 stats_thread->stop();
 618                 stats_thread.reset();
 619         }
 620         for (Acceptor *acceptor : acceptors) {
 621                 acceptor->stop();
 622         }
 623         for (const auto &key_and_input_with_refcount : inputs) {
 624                 key_and_input_with_refcount.second.input->stop();
 625         }
 626         servers->stop();
 627
 628         CubemapStateProto state;
 629         if (stopped) {
 630                 log(INFO, "Shutting down.");
 631         } else {
 632                 log(INFO, "Serializing state and re-execing...");
 633                 state = collect_state(
 634                         serialize_start, acceptors, inputs, servers);
 635                 string serialized;
 636                 state.SerializeToString(&serialized);
 637                 state_fd = make_tempfile(serialized);
 638                 if (state_fd == -1) {
 639                         exit(1);
 640                 }
 641         }
 642         delete servers;
 643
 644         access_log->stop();
 645         delete access_log;
 646         shut_down_logging();
 647
 648         if (stopped) {
 649                 exit(0);
 650         }
 651
 652         // OK, so the signal was SIGHUP. Check that the new config is okay, then exec the new binary.
 653         if (!dry_run_config(argv0_canon, config_filename_canon)) {
 654                 open_logs(config.log_destinations);
 655                 log(ERROR, "%s --test-config failed. Restarting old version instead of new.", argv[0]);
 656                 hupped = false;
 657                 shut_down_logging();
 658                 goto start;
 659         }
 660
 661         char buf[16];
 662         sprintf(buf, "%d", state_fd);
 663
 664         for ( ;; ) {
 665                 execlp(argv0_canon, argv0_canon, config_filename_canon, "--state", buf, nullptr);
 666                 open_logs(config.log_destinations);
 667                 log_perror("execlp");
 668                 log(ERROR, "re-exec of %s failed. Waiting 0.2 seconds and trying again...", argv0_canon);
 669                 shut_down_logging();
 670                 usleep(200000);
 671         }
 672 }