src/socket-proxy/socket-proxyd.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <getopt.h>
   6 #include <netdb.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include <sys/socket.h>
  11 #include <sys/un.h>
  12 #include <unistd.h>
  13
  14 #include "sd-daemon.h"
  15 #include "sd-event.h"
  16 #include "sd-resolve.h"
  17
  18 #include "alloc-util.h"
  19 #include "fd-util.h"
  20 #include "log.h"
  21 #include "path-util.h"
  22 #include "set.h"
  23 #include "socket-util.h"
  24 #include "string-util.h"
  25 #include "parse-util.h"
  26 #include "util.h"
  27
  28 #define BUFFER_SIZE (256 * 1024)
  29 static unsigned arg_connections_max = 256;
  30
  31 static const char *arg_remote_host = NULL;
  32
  33 typedef struct Context {
  34         sd_event *event;
  35         sd_resolve *resolve;
  36
  37         Set *listen;
  38         Set *connections;
  39 } Context;
  40
  41 typedef struct Connection {
  42         Context *context;
  43
  44         int server_fd, client_fd;
  45         int server_to_client_buffer[2]; /* a pipe */
  46         int client_to_server_buffer[2]; /* a pipe */
  47
  48         size_t server_to_client_buffer_full, client_to_server_buffer_full;
  49         size_t server_to_client_buffer_size, client_to_server_buffer_size;
  50
  51         sd_event_source *server_event_source, *client_event_source;
  52
  53         sd_resolve_query *resolve_query;
  54 } Connection;
  55
  56 static void connection_free(Connection *c) {
  57         assert(c);
  58
  59         if (c->context)
  60                 set_remove(c->context->connections, c);
  61
  62         sd_event_source_unref(c->server_event_source);
  63         sd_event_source_unref(c->client_event_source);
  64
  65         safe_close(c->server_fd);
  66         safe_close(c->client_fd);
  67
  68         safe_close_pair(c->server_to_client_buffer);
  69         safe_close_pair(c->client_to_server_buffer);
  70
  71         sd_resolve_query_unref(c->resolve_query);
  72
  73         free(c);
  74 }
  75
  76 static void context_free(Context *context) {
  77         assert(context);
  78
  79         set_free_with_destructor(context->listen, sd_event_source_unref);
  80         set_free_with_destructor(context->connections, connection_free);
  81
  82         sd_event_unref(context->event);
  83         sd_resolve_unref(context->resolve);
  84 }
  85
  86 static int connection_create_pipes(Connection *c, int buffer[2], size_t *sz) {
  87         int r;
  88
  89         assert(c);
  90         assert(buffer);
  91         assert(sz);
  92
  93         if (buffer[0] >= 0)
  94                 return 0;
  95
  96         r = pipe2(buffer, O_CLOEXEC|O_NONBLOCK);
  97         if (r < 0)
  98                 return log_error_errno(errno, "Failed to allocate pipe buffer: %m");
  99
 100         (void) fcntl(buffer[0], F_SETPIPE_SZ, BUFFER_SIZE);
 101
 102         r = fcntl(buffer[0], F_GETPIPE_SZ);
 103         if (r < 0)
 104                 return log_error_errno(errno, "Failed to get pipe buffer size: %m");
 105
 106         assert(r > 0);
 107         *sz = r;
 108
 109         return 0;
 110 }
 111
 112 static int connection_shovel(
 113                 Connection *c,
 114                 int *from, int buffer[2], int *to,
 115                 size_t *full, size_t *sz,
 116                 sd_event_source **from_source, sd_event_source **to_source) {
 117
 118         bool shoveled;
 119
 120         assert(c);
 121         assert(from);
 122         assert(buffer);
 123         assert(buffer[0] >= 0);
 124         assert(buffer[1] >= 0);
 125         assert(to);
 126         assert(full);
 127         assert(sz);
 128         assert(from_source);
 129         assert(to_source);
 130
 131         do {
 132                 ssize_t z;
 133
 134                 shoveled = false;
 135
 136                 if (*full < *sz && *from >= 0 && *to >= 0) {
 137                         z = splice(*from, NULL, buffer[1], NULL, *sz - *full, SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
 138                         if (z > 0) {
 139                                 *full += z;
 140                                 shoveled = true;
 141                         } else if (z == 0 || IN_SET(errno, EPIPE, ECONNRESET)) {
 142                                 *from_source = sd_event_source_unref(*from_source);
 143                                 *from = safe_close(*from);
 144                         } else if (!IN_SET(errno, EAGAIN, EINTR))
 145                                 return log_error_errno(errno, "Failed to splice: %m");
 146                 }
 147
 148                 if (*full > 0 && *to >= 0) {
 149                         z = splice(buffer[0], NULL, *to, NULL, *full, SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
 150                         if (z > 0) {
 151                                 *full -= z;
 152                                 shoveled = true;
 153                         } else if (z == 0 || IN_SET(errno, EPIPE, ECONNRESET)) {
 154                                 *to_source = sd_event_source_unref(*to_source);
 155                                 *to = safe_close(*to);
 156                         } else if (!IN_SET(errno, EAGAIN, EINTR))
 157                                 return log_error_errno(errno, "Failed to splice: %m");
 158                 }
 159         } while (shoveled);
 160
 161         return 0;
 162 }
 163
 164 static int connection_enable_event_sources(Connection *c);
 165
 166 static int traffic_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 167         Connection *c = userdata;
 168         int r;
 169
 170         assert(s);
 171         assert(fd >= 0);
 172         assert(c);
 173
 174         r = connection_shovel(c,
 175                               &c->server_fd, c->server_to_client_buffer, &c->client_fd,
 176                               &c->server_to_client_buffer_full, &c->server_to_client_buffer_size,
 177                               &c->server_event_source, &c->client_event_source);
 178         if (r < 0)
 179                 goto quit;
 180
 181         r = connection_shovel(c,
 182                               &c->client_fd, c->client_to_server_buffer, &c->server_fd,
 183                               &c->client_to_server_buffer_full, &c->client_to_server_buffer_size,
 184                               &c->client_event_source, &c->server_event_source);
 185         if (r < 0)
 186                 goto quit;
 187
 188         /* EOF on both sides? */
 189         if (c->server_fd == -1 && c->client_fd == -1)
 190                 goto quit;
 191
 192         /* Server closed, and all data written to client? */
 193         if (c->server_fd == -1 && c->server_to_client_buffer_full <= 0)
 194                 goto quit;
 195
 196         /* Client closed, and all data written to server? */
 197         if (c->client_fd == -1 && c->client_to_server_buffer_full <= 0)
 198                 goto quit;
 199
 200         r = connection_enable_event_sources(c);
 201         if (r < 0)
 202                 goto quit;
 203
 204         return 1;
 205
 206 quit:
 207         connection_free(c);
 208         return 0; /* ignore errors, continue serving */
 209 }
 210
 211 static int connection_enable_event_sources(Connection *c) {
 212         uint32_t a = 0, b = 0;
 213         int r;
 214
 215         assert(c);
 216
 217         if (c->server_to_client_buffer_full > 0)
 218                 b |= EPOLLOUT;
 219         if (c->server_to_client_buffer_full < c->server_to_client_buffer_size)
 220                 a |= EPOLLIN;
 221
 222         if (c->client_to_server_buffer_full > 0)
 223                 a |= EPOLLOUT;
 224         if (c->client_to_server_buffer_full < c->client_to_server_buffer_size)
 225                 b |= EPOLLIN;
 226
 227         if (c->server_event_source)
 228                 r = sd_event_source_set_io_events(c->server_event_source, a);
 229         else if (c->server_fd >= 0)
 230                 r = sd_event_add_io(c->context->event, &c->server_event_source, c->server_fd, a, traffic_cb, c);
 231         else
 232                 r = 0;
 233
 234         if (r < 0)
 235                 return log_error_errno(r, "Failed to set up server event source: %m");
 236
 237         if (c->client_event_source)
 238                 r = sd_event_source_set_io_events(c->client_event_source, b);
 239         else if (c->client_fd >= 0)
 240                 r = sd_event_add_io(c->context->event, &c->client_event_source, c->client_fd, b, traffic_cb, c);
 241         else
 242                 r = 0;
 243
 244         if (r < 0)
 245                 return log_error_errno(r, "Failed to set up client event source: %m");
 246
 247         return 0;
 248 }
 249
 250 static int connection_complete(Connection *c) {
 251         int r;
 252
 253         assert(c);
 254
 255         r = connection_create_pipes(c, c->server_to_client_buffer, &c->server_to_client_buffer_size);
 256         if (r < 0)
 257                 goto fail;
 258
 259         r = connection_create_pipes(c, c->client_to_server_buffer, &c->client_to_server_buffer_size);
 260         if (r < 0)
 261                 goto fail;
 262
 263         r = connection_enable_event_sources(c);
 264         if (r < 0)
 265                 goto fail;
 266
 267         return 0;
 268
 269 fail:
 270         connection_free(c);
 271         return 0; /* ignore errors, continue serving */
 272 }
 273
 274 static int connect_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 275         Connection *c = userdata;
 276         socklen_t solen;
 277         int error, r;
 278
 279         assert(s);
 280         assert(fd >= 0);
 281         assert(c);
 282
 283         solen = sizeof(error);
 284         r = getsockopt(fd, SOL_SOCKET, SO_ERROR, &error, &solen);
 285         if (r < 0) {
 286                 log_error_errno(errno, "Failed to issue SO_ERROR: %m");
 287                 goto fail;
 288         }
 289
 290         if (error != 0) {
 291                 log_error_errno(error, "Failed to connect to remote host: %m");
 292                 goto fail;
 293         }
 294
 295         c->client_event_source = sd_event_source_unref(c->client_event_source);
 296
 297         return connection_complete(c);
 298
 299 fail:
 300         connection_free(c);
 301         return 0; /* ignore errors, continue serving */
 302 }
 303
 304 static int connection_start(Connection *c, struct sockaddr *sa, socklen_t salen) {
 305         int r;
 306
 307         assert(c);
 308         assert(sa);
 309         assert(salen);
 310
 311         c->client_fd = socket(sa->sa_family, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
 312         if (c->client_fd < 0) {
 313                 log_error_errno(errno, "Failed to get remote socket: %m");
 314                 goto fail;
 315         }
 316
 317         r = connect(c->client_fd, sa, salen);
 318         if (r < 0) {
 319                 if (errno == EINPROGRESS) {
 320                         r = sd_event_add_io(c->context->event, &c->client_event_source, c->client_fd, EPOLLOUT, connect_cb, c);
 321                         if (r < 0) {
 322                                 log_error_errno(r, "Failed to add connection socket: %m");
 323                                 goto fail;
 324                         }
 325
 326                         r = sd_event_source_set_enabled(c->client_event_source, SD_EVENT_ONESHOT);
 327                         if (r < 0) {
 328                                 log_error_errno(r, "Failed to enable oneshot event source: %m");
 329                                 goto fail;
 330                         }
 331                 } else {
 332                         log_error_errno(errno, "Failed to connect to remote host: %m");
 333                         goto fail;
 334                 }
 335         } else {
 336                 r = connection_complete(c);
 337                 if (r < 0)
 338                         goto fail;
 339         }
 340
 341         return 0;
 342
 343 fail:
 344         connection_free(c);
 345         return 0; /* ignore errors, continue serving */
 346 }
 347
 348 static int resolve_cb(sd_resolve_query *q, int ret, const struct addrinfo *ai, void *userdata) {
 349         Connection *c = userdata;
 350
 351         assert(q);
 352         assert(c);
 353
 354         if (ret != 0) {
 355                 log_error("Failed to resolve host: %s", gai_strerror(ret));
 356                 goto fail;
 357         }
 358
 359         c->resolve_query = sd_resolve_query_unref(c->resolve_query);
 360
 361         return connection_start(c, ai->ai_addr, ai->ai_addrlen);
 362
 363 fail:
 364         connection_free(c);
 365         return 0; /* ignore errors, continue serving */
 366 }
 367
 368 static int resolve_remote(Connection *c) {
 369
 370         static const struct addrinfo hints = {
 371                 .ai_family = AF_UNSPEC,
 372                 .ai_socktype = SOCK_STREAM,
 373                 .ai_flags = AI_ADDRCONFIG
 374         };
 375
 376         union sockaddr_union sa = {};
 377         const char *node, *service;
 378         int r;
 379
 380         if (path_is_absolute(arg_remote_host)) {
 381                 sa.un.sun_family = AF_UNIX;
 382                 strncpy(sa.un.sun_path, arg_remote_host, sizeof(sa.un.sun_path));
 383                 return connection_start(c, &sa.sa, SOCKADDR_UN_LEN(sa.un));
 384         }
 385
 386         if (arg_remote_host[0] == '@') {
 387                 sa.un.sun_family = AF_UNIX;
 388                 sa.un.sun_path[0] = 0;
 389                 strncpy(sa.un.sun_path+1, arg_remote_host+1, sizeof(sa.un.sun_path)-1);
 390                 return connection_start(c, &sa.sa, SOCKADDR_UN_LEN(sa.un));
 391         }
 392
 393         service = strrchr(arg_remote_host, ':');
 394         if (service) {
 395                 node = strndupa(arg_remote_host, service - arg_remote_host);
 396                 service++;
 397         } else {
 398                 node = arg_remote_host;
 399                 service = "80";
 400         }
 401
 402         log_debug("Looking up address info for %s:%s", node, service);
 403         r = sd_resolve_getaddrinfo(c->context->resolve, &c->resolve_query, node, service, &hints, resolve_cb, c);
 404         if (r < 0) {
 405                 log_error_errno(r, "Failed to resolve remote host: %m");
 406                 goto fail;
 407         }
 408
 409         return 0;
 410
 411 fail:
 412         connection_free(c);
 413         return 0; /* ignore errors, continue serving */
 414 }
 415
 416 static int add_connection_socket(Context *context, int fd) {
 417         Connection *c;
 418         int r;
 419
 420         assert(context);
 421         assert(fd >= 0);
 422
 423         if (set_size(context->connections) > arg_connections_max) {
 424                 log_warning("Hit connection limit, refusing connection.");
 425                 safe_close(fd);
 426                 return 0;
 427         }
 428
 429         r = set_ensure_allocated(&context->connections, NULL);
 430         if (r < 0) {
 431                 log_oom();
 432                 return 0;
 433         }
 434
 435         c = new0(Connection, 1);
 436         if (!c) {
 437                 log_oom();
 438                 return 0;
 439         }
 440
 441         c->context = context;
 442         c->server_fd = fd;
 443         c->client_fd = -1;
 444         c->server_to_client_buffer[0] = c->server_to_client_buffer[1] = -1;
 445         c->client_to_server_buffer[0] = c->client_to_server_buffer[1] = -1;
 446
 447         r = set_put(context->connections, c);
 448         if (r < 0) {
 449                 free(c);
 450                 log_oom();
 451                 return 0;
 452         }
 453
 454         return resolve_remote(c);
 455 }
 456
 457 static int accept_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 458         _cleanup_free_ char *peer = NULL;
 459         Context *context = userdata;
 460         int nfd = -1, r;
 461
 462         assert(s);
 463         assert(fd >= 0);
 464         assert(revents & EPOLLIN);
 465         assert(context);
 466
 467         nfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
 468         if (nfd < 0) {
 469                 if (errno != -EAGAIN)
 470                         log_warning_errno(errno, "Failed to accept() socket: %m");
 471         } else {
 472                 getpeername_pretty(nfd, true, &peer);
 473                 log_debug("New connection from %s", strna(peer));
 474
 475                 r = add_connection_socket(context, nfd);
 476                 if (r < 0) {
 477                         log_error_errno(r, "Failed to accept connection, ignoring: %m");
 478                         safe_close(fd);
 479                 }
 480         }
 481
 482         r = sd_event_source_set_enabled(s, SD_EVENT_ONESHOT);
 483         if (r < 0) {
 484                 log_error_errno(r, "Error while re-enabling listener with ONESHOT: %m");
 485                 sd_event_exit(context->event, r);
 486                 return r;
 487         }
 488
 489         return 1;
 490 }
 491
 492 static int add_listen_socket(Context *context, int fd) {
 493         sd_event_source *source;
 494         int r;
 495
 496         assert(context);
 497         assert(fd >= 0);
 498
 499         r = set_ensure_allocated(&context->listen, NULL);
 500         if (r < 0) {
 501                 log_oom();
 502                 return r;
 503         }
 504
 505         r = sd_is_socket(fd, 0, SOCK_STREAM, 1);
 506         if (r < 0)
 507                 return log_error_errno(r, "Failed to determine socket type: %m");
 508         if (r == 0) {
 509                 log_error("Passed in socket is not a stream socket.");
 510                 return -EINVAL;
 511         }
 512
 513         r = fd_nonblock(fd, true);
 514         if (r < 0)
 515                 return log_error_errno(r, "Failed to mark file descriptor non-blocking: %m");
 516
 517         r = sd_event_add_io(context->event, &source, fd, EPOLLIN, accept_cb, context);
 518         if (r < 0)
 519                 return log_error_errno(r, "Failed to add event source: %m");
 520
 521         r = set_put(context->listen, source);
 522         if (r < 0) {
 523                 log_error_errno(r, "Failed to add source to set: %m");
 524                 sd_event_source_unref(source);
 525                 return r;
 526         }
 527
 528         /* Set the watcher to oneshot in case other processes are also
 529          * watching to accept(). */
 530         r = sd_event_source_set_enabled(source, SD_EVENT_ONESHOT);
 531         if (r < 0)
 532                 return log_error_errno(r, "Failed to enable oneshot mode: %m");
 533
 534         return 0;
 535 }
 536
 537 static void help(void) {
 538         printf("%1$s [HOST:PORT]\n"
 539                "%1$s [SOCKET]\n\n"
 540                "Bidirectionally proxy local sockets to another (possibly remote) socket.\n\n"
 541                "  -c --connections-max=  Set the maximum number of connections to be accepted\n"
 542                "  -h --help              Show this help\n"
 543                "     --version           Show package version\n",
 544                program_invocation_short_name);
 545 }
 546
 547 static int parse_argv(int argc, char *argv[]) {
 548
 549         enum {
 550                 ARG_VERSION = 0x100,
 551                 ARG_IGNORE_ENV
 552         };
 553
 554         static const struct option options[] = {
 555                 { "connections-max", required_argument, NULL, 'c'           },
 556                 { "help",            no_argument,       NULL, 'h'           },
 557                 { "version",         no_argument,       NULL, ARG_VERSION   },
 558                 {}
 559         };
 560
 561         int c, r;
 562
 563         assert(argc >= 0);
 564         assert(argv);
 565
 566         while ((c = getopt_long(argc, argv, "c:h", options, NULL)) >= 0)
 567
 568                 switch (c) {
 569
 570                 case 'h':
 571                         help();
 572                         return 0;
 573
 574                 case 'c':
 575                         r = safe_atou(optarg, &arg_connections_max);
 576                         if (r < 0) {
 577                                 log_error("Failed to parse --connections-max= argument: %s", optarg);
 578                                 return r;
 579                         }
 580
 581                         if (arg_connections_max < 1) {
 582                                 log_error("Connection limit is too low.");
 583                                 return -EINVAL;
 584                         }
 585
 586                         break;
 587
 588                 case ARG_VERSION:
 589                         return version();
 590
 591                 case '?':
 592                         return -EINVAL;
 593
 594                 default:
 595                         assert_not_reached("Unhandled option");
 596                 }
 597
 598         if (optind >= argc) {
 599                 log_error("Not enough parameters.");
 600                 return -EINVAL;
 601         }
 602
 603         if (argc != optind+1) {
 604                 log_error("Too many parameters.");
 605                 return -EINVAL;
 606         }
 607
 608         arg_remote_host = argv[optind];
 609         return 1;
 610 }
 611
 612 int main(int argc, char *argv[]) {
 613         Context context = {};
 614         int r, n, fd;
 615
 616         log_parse_environment();
 617         log_open();
 618
 619         r = parse_argv(argc, argv);
 620         if (r <= 0)
 621                 goto finish;
 622
 623         r = sd_event_default(&context.event);
 624         if (r < 0) {
 625                 log_error_errno(r, "Failed to allocate event loop: %m");
 626                 goto finish;
 627         }
 628
 629         r = sd_resolve_default(&context.resolve);
 630         if (r < 0) {
 631                 log_error_errno(r, "Failed to allocate resolver: %m");
 632                 goto finish;
 633         }
 634
 635         r = sd_resolve_attach_event(context.resolve, context.event, 0);
 636         if (r < 0) {
 637                 log_error_errno(r, "Failed to attach resolver: %m");
 638                 goto finish;
 639         }
 640
 641         sd_event_set_watchdog(context.event, true);
 642
 643         n = sd_listen_fds(1);
 644         if (n < 0) {
 645                 log_error("Failed to receive sockets from parent.");
 646                 r = n;
 647                 goto finish;
 648         } else if (n == 0) {
 649                 log_error("Didn't get any sockets passed in.");
 650                 r = -EINVAL;
 651                 goto finish;
 652         }
 653
 654         for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
 655                 r = add_listen_socket(&context, fd);
 656                 if (r < 0)
 657                         goto finish;
 658         }
 659
 660         r = sd_event_loop(context.event);
 661         if (r < 0) {
 662                 log_error_errno(r, "Failed to run event loop: %m");
 663                 goto finish;
 664         }
 665
 666 finish:
 667         context_free(&context);
 668
 669         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 670 }