src/socket-proxy/socket-proxyd.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2013 David Strauss
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20  ***/
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <getopt.h>
  25 #include <netdb.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <sys/socket.h>
  30 #include <sys/un.h>
  31 #include <unistd.h>
  32
  33 #include "sd-daemon.h"
  34 #include "sd-event.h"
  35 #include "sd-resolve.h"
  36
  37 #include "log.h"
  38 #include "path-util.h"
  39 #include "set.h"
  40 #include "socket-util.h"
  41 #include "util.h"
  42
  43 #define BUFFER_SIZE (256 * 1024)
  44 #define CONNECTIONS_MAX 256
  45
  46 static const char *arg_remote_host = NULL;
  47
  48 typedef struct Context {
  49         sd_event *event;
  50         sd_resolve *resolve;
  51
  52         Set *listen;
  53         Set *connections;
  54 } Context;
  55
  56 typedef struct Connection {
  57         Context *context;
  58
  59         int server_fd, client_fd;
  60         int server_to_client_buffer[2]; /* a pipe */
  61         int client_to_server_buffer[2]; /* a pipe */
  62
  63         size_t server_to_client_buffer_full, client_to_server_buffer_full;
  64         size_t server_to_client_buffer_size, client_to_server_buffer_size;
  65
  66         sd_event_source *server_event_source, *client_event_source;
  67
  68         sd_resolve_query *resolve_query;
  69 } Connection;
  70
  71 static void connection_free(Connection *c) {
  72         assert(c);
  73
  74         if (c->context)
  75                 set_remove(c->context->connections, c);
  76
  77         sd_event_source_unref(c->server_event_source);
  78         sd_event_source_unref(c->client_event_source);
  79
  80         safe_close(c->server_fd);
  81         safe_close(c->client_fd);
  82
  83         safe_close_pair(c->server_to_client_buffer);
  84         safe_close_pair(c->client_to_server_buffer);
  85
  86         sd_resolve_query_unref(c->resolve_query);
  87
  88         free(c);
  89 }
  90
  91 static void context_free(Context *context) {
  92         sd_event_source *es;
  93         Connection *c;
  94
  95         assert(context);
  96
  97         while ((es = set_steal_first(context->listen)))
  98                 sd_event_source_unref(es);
  99
 100         while ((c = set_first(context->connections)))
 101                 connection_free(c);
 102
 103         set_free(context->listen);
 104         set_free(context->connections);
 105
 106         sd_event_unref(context->event);
 107         sd_resolve_unref(context->resolve);
 108 }
 109
 110 static int connection_create_pipes(Connection *c, int buffer[2], size_t *sz) {
 111         int r;
 112
 113         assert(c);
 114         assert(buffer);
 115         assert(sz);
 116
 117         if (buffer[0] >= 0)
 118                 return 0;
 119
 120         r = pipe2(buffer, O_CLOEXEC|O_NONBLOCK);
 121         if (r < 0)
 122                 return log_error_errno(errno, "Failed to allocate pipe buffer: %m");
 123
 124         (void) fcntl(buffer[0], F_SETPIPE_SZ, BUFFER_SIZE);
 125
 126         r = fcntl(buffer[0], F_GETPIPE_SZ);
 127         if (r < 0)
 128                 return log_error_errno(errno, "Failed to get pipe buffer size: %m");
 129
 130         assert(r > 0);
 131         *sz = r;
 132
 133         return 0;
 134 }
 135
 136 static int connection_shovel(
 137                 Connection *c,
 138                 int *from, int buffer[2], int *to,
 139                 size_t *full, size_t *sz,
 140                 sd_event_source **from_source, sd_event_source **to_source) {
 141
 142         bool shoveled;
 143
 144         assert(c);
 145         assert(from);
 146         assert(buffer);
 147         assert(buffer[0] >= 0);
 148         assert(buffer[1] >= 0);
 149         assert(to);
 150         assert(full);
 151         assert(sz);
 152         assert(from_source);
 153         assert(to_source);
 154
 155         do {
 156                 ssize_t z;
 157
 158                 shoveled = false;
 159
 160                 if (*full < *sz && *from >= 0 && *to >= 0) {
 161                         z = splice(*from, NULL, buffer[1], NULL, *sz - *full, SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
 162                         if (z > 0) {
 163                                 *full += z;
 164                                 shoveled = true;
 165                         } else if (z == 0 || errno == EPIPE || errno == ECONNRESET) {
 166                                 *from_source = sd_event_source_unref(*from_source);
 167                                 *from = safe_close(*from);
 168                         } else if (errno != EAGAIN && errno != EINTR)
 169                                 return log_error_errno(errno, "Failed to splice: %m");
 170                 }
 171
 172                 if (*full > 0 && *to >= 0) {
 173                         z = splice(buffer[0], NULL, *to, NULL, *full, SPLICE_F_MOVE|SPLICE_F_NONBLOCK);
 174                         if (z > 0) {
 175                                 *full -= z;
 176                                 shoveled = true;
 177                         } else if (z == 0 || errno == EPIPE || errno == ECONNRESET) {
 178                                 *to_source = sd_event_source_unref(*to_source);
 179                                 *to = safe_close(*to);
 180                         } else if (errno != EAGAIN && errno != EINTR)
 181                                 return log_error_errno(errno, "Failed to splice: %m");
 182                 }
 183         } while (shoveled);
 184
 185         return 0;
 186 }
 187
 188 static int connection_enable_event_sources(Connection *c);
 189
 190 static int traffic_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 191         Connection *c = userdata;
 192         int r;
 193
 194         assert(s);
 195         assert(fd >= 0);
 196         assert(c);
 197
 198         r = connection_shovel(c,
 199                               &c->server_fd, c->server_to_client_buffer, &c->client_fd,
 200                               &c->server_to_client_buffer_full, &c->server_to_client_buffer_size,
 201                               &c->server_event_source, &c->client_event_source);
 202         if (r < 0)
 203                 goto quit;
 204
 205         r = connection_shovel(c,
 206                               &c->client_fd, c->client_to_server_buffer, &c->server_fd,
 207                               &c->client_to_server_buffer_full, &c->client_to_server_buffer_size,
 208                               &c->client_event_source, &c->server_event_source);
 209         if (r < 0)
 210                 goto quit;
 211
 212         /* EOF on both sides? */
 213         if (c->server_fd == -1 && c->client_fd == -1)
 214                 goto quit;
 215
 216         /* Server closed, and all data written to client? */
 217         if (c->server_fd == -1 && c->server_to_client_buffer_full <= 0)
 218                 goto quit;
 219
 220         /* Client closed, and all data written to server? */
 221         if (c->client_fd == -1 && c->client_to_server_buffer_full <= 0)
 222                 goto quit;
 223
 224         r = connection_enable_event_sources(c);
 225         if (r < 0)
 226                 goto quit;
 227
 228         return 1;
 229
 230 quit:
 231         connection_free(c);
 232         return 0; /* ignore errors, continue serving */
 233 }
 234
 235 static int connection_enable_event_sources(Connection *c) {
 236         uint32_t a = 0, b = 0;
 237         int r;
 238
 239         assert(c);
 240
 241         if (c->server_to_client_buffer_full > 0)
 242                 b |= EPOLLOUT;
 243         if (c->server_to_client_buffer_full < c->server_to_client_buffer_size)
 244                 a |= EPOLLIN;
 245
 246         if (c->client_to_server_buffer_full > 0)
 247                 a |= EPOLLOUT;
 248         if (c->client_to_server_buffer_full < c->client_to_server_buffer_size)
 249                 b |= EPOLLIN;
 250
 251         if (c->server_event_source)
 252                 r = sd_event_source_set_io_events(c->server_event_source, a);
 253         else if (c->server_fd >= 0)
 254                 r = sd_event_add_io(c->context->event, &c->server_event_source, c->server_fd, a, traffic_cb, c);
 255         else
 256                 r = 0;
 257
 258         if (r < 0)
 259                 return log_error_errno(r, "Failed to set up server event source: %m");
 260
 261         if (c->client_event_source)
 262                 r = sd_event_source_set_io_events(c->client_event_source, b);
 263         else if (c->client_fd >= 0)
 264                 r = sd_event_add_io(c->context->event, &c->client_event_source, c->client_fd, b, traffic_cb, c);
 265         else
 266                 r = 0;
 267
 268         if (r < 0)
 269                 return log_error_errno(r, "Failed to set up client event source: %m");
 270
 271         return 0;
 272 }
 273
 274 static int connection_complete(Connection *c) {
 275         int r;
 276
 277         assert(c);
 278
 279         r = connection_create_pipes(c, c->server_to_client_buffer, &c->server_to_client_buffer_size);
 280         if (r < 0)
 281                 goto fail;
 282
 283         r = connection_create_pipes(c, c->client_to_server_buffer, &c->client_to_server_buffer_size);
 284         if (r < 0)
 285                 goto fail;
 286
 287         r = connection_enable_event_sources(c);
 288         if (r < 0)
 289                 goto fail;
 290
 291         return 0;
 292
 293 fail:
 294         connection_free(c);
 295         return 0; /* ignore errors, continue serving */
 296 }
 297
 298 static int connect_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 299         Connection *c = userdata;
 300         socklen_t solen;
 301         int error, r;
 302
 303         assert(s);
 304         assert(fd >= 0);
 305         assert(c);
 306
 307         solen = sizeof(error);
 308         r = getsockopt(fd, SOL_SOCKET, SO_ERROR, &error, &solen);
 309         if (r < 0) {
 310                 log_error_errno(errno, "Failed to issue SO_ERROR: %m");
 311                 goto fail;
 312         }
 313
 314         if (error != 0) {
 315                 log_error_errno(error, "Failed to connect to remote host: %m");
 316                 goto fail;
 317         }
 318
 319         c->client_event_source = sd_event_source_unref(c->client_event_source);
 320
 321         return connection_complete(c);
 322
 323 fail:
 324         connection_free(c);
 325         return 0; /* ignore errors, continue serving */
 326 }
 327
 328 static int connection_start(Connection *c, struct sockaddr *sa, socklen_t salen) {
 329         int r;
 330
 331         assert(c);
 332         assert(sa);
 333         assert(salen);
 334
 335         c->client_fd = socket(sa->sa_family, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
 336         if (c->client_fd < 0) {
 337                 log_error_errno(errno, "Failed to get remote socket: %m");
 338                 goto fail;
 339         }
 340
 341         r = connect(c->client_fd, sa, salen);
 342         if (r < 0) {
 343                 if (errno == EINPROGRESS) {
 344                         r = sd_event_add_io(c->context->event, &c->client_event_source, c->client_fd, EPOLLOUT, connect_cb, c);
 345                         if (r < 0) {
 346                                 log_error_errno(r, "Failed to add connection socket: %m");
 347                                 goto fail;
 348                         }
 349
 350                         r = sd_event_source_set_enabled(c->client_event_source, SD_EVENT_ONESHOT);
 351                         if (r < 0) {
 352                                 log_error_errno(r, "Failed to enable oneshot event source: %m");
 353                                 goto fail;
 354                         }
 355                 } else {
 356                         log_error_errno(errno, "Failed to connect to remote host: %m");
 357                         goto fail;
 358                 }
 359         } else {
 360                 r = connection_complete(c);
 361                 if (r < 0)
 362                         goto fail;
 363         }
 364
 365         return 0;
 366
 367 fail:
 368         connection_free(c);
 369         return 0; /* ignore errors, continue serving */
 370 }
 371
 372 static int resolve_cb(sd_resolve_query *q, int ret, const struct addrinfo *ai, void *userdata) {
 373         Connection *c = userdata;
 374
 375         assert(q);
 376         assert(c);
 377
 378         if (ret != 0) {
 379                 log_error("Failed to resolve host: %s", gai_strerror(ret));
 380                 goto fail;
 381         }
 382
 383         c->resolve_query = sd_resolve_query_unref(c->resolve_query);
 384
 385         return connection_start(c, ai->ai_addr, ai->ai_addrlen);
 386
 387 fail:
 388         connection_free(c);
 389         return 0; /* ignore errors, continue serving */
 390 }
 391
 392 static int resolve_remote(Connection *c) {
 393
 394         static const struct addrinfo hints = {
 395                 .ai_family = AF_UNSPEC,
 396                 .ai_socktype = SOCK_STREAM,
 397                 .ai_flags = AI_ADDRCONFIG
 398         };
 399
 400         union sockaddr_union sa = {};
 401         const char *node, *service;
 402         socklen_t salen;
 403         int r;
 404
 405         if (path_is_absolute(arg_remote_host)) {
 406                 sa.un.sun_family = AF_UNIX;
 407                 strncpy(sa.un.sun_path, arg_remote_host, sizeof(sa.un.sun_path)-1);
 408                 sa.un.sun_path[sizeof(sa.un.sun_path)-1] = 0;
 409
 410                 salen = offsetof(union sockaddr_union, un.sun_path) + strlen(sa.un.sun_path);
 411
 412                 return connection_start(c, &sa.sa, salen);
 413         }
 414
 415         if (arg_remote_host[0] == '@') {
 416                 sa.un.sun_family = AF_UNIX;
 417                 sa.un.sun_path[0] = 0;
 418                 strncpy(sa.un.sun_path+1, arg_remote_host+1, sizeof(sa.un.sun_path)-2);
 419                 sa.un.sun_path[sizeof(sa.un.sun_path)-1] = 0;
 420
 421                 salen = offsetof(union sockaddr_union, un.sun_path) + 1 + strlen(sa.un.sun_path + 1);
 422
 423                 return connection_start(c, &sa.sa, salen);
 424         }
 425
 426         service = strrchr(arg_remote_host, ':');
 427         if (service) {
 428                 node = strndupa(arg_remote_host, service - arg_remote_host);
 429                 service ++;
 430         } else {
 431                 node = arg_remote_host;
 432                 service = "80";
 433         }
 434
 435         log_debug("Looking up address info for %s:%s", node, service);
 436         r = sd_resolve_getaddrinfo(c->context->resolve, &c->resolve_query, node, service, &hints, resolve_cb, c);
 437         if (r < 0) {
 438                 log_error_errno(r, "Failed to resolve remote host: %m");
 439                 goto fail;
 440         }
 441
 442         return 0;
 443
 444 fail:
 445         connection_free(c);
 446         return 0; /* ignore errors, continue serving */
 447 }
 448
 449 static int add_connection_socket(Context *context, int fd) {
 450         Connection *c;
 451         int r;
 452
 453         assert(context);
 454         assert(fd >= 0);
 455
 456         if (set_size(context->connections) > CONNECTIONS_MAX) {
 457                 log_warning("Hit connection limit, refusing connection.");
 458                 safe_close(fd);
 459                 return 0;
 460         }
 461
 462         r = set_ensure_allocated(&context->connections, NULL);
 463         if (r < 0) {
 464                 log_oom();
 465                 return 0;
 466         }
 467
 468         c = new0(Connection, 1);
 469         if (!c) {
 470                 log_oom();
 471                 return 0;
 472         }
 473
 474         c->context = context;
 475         c->server_fd = fd;
 476         c->client_fd = -1;
 477         c->server_to_client_buffer[0] = c->server_to_client_buffer[1] = -1;
 478         c->client_to_server_buffer[0] = c->client_to_server_buffer[1] = -1;
 479
 480         r = set_put(context->connections, c);
 481         if (r < 0) {
 482                 free(c);
 483                 log_oom();
 484                 return 0;
 485         }
 486
 487         return resolve_remote(c);
 488 }
 489
 490 static int accept_cb(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 491         _cleanup_free_ char *peer = NULL;
 492         Context *context = userdata;
 493         int nfd = -1, r;
 494
 495         assert(s);
 496         assert(fd >= 0);
 497         assert(revents & EPOLLIN);
 498         assert(context);
 499
 500         nfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
 501         if (nfd < 0) {
 502                 if (errno != -EAGAIN)
 503                         log_warning_errno(errno, "Failed to accept() socket: %m");
 504         } else {
 505                 getpeername_pretty(nfd, &peer);
 506                 log_debug("New connection from %s", strna(peer));
 507
 508                 r = add_connection_socket(context, nfd);
 509                 if (r < 0) {
 510                         log_error_errno(r, "Failed to accept connection, ignoring: %m");
 511                         safe_close(fd);
 512                 }
 513         }
 514
 515         r = sd_event_source_set_enabled(s, SD_EVENT_ONESHOT);
 516         if (r < 0) {
 517                 log_error_errno(r, "Error while re-enabling listener with ONESHOT: %m");
 518                 sd_event_exit(context->event, r);
 519                 return r;
 520         }
 521
 522         return 1;
 523 }
 524
 525 static int add_listen_socket(Context *context, int fd) {
 526         sd_event_source *source;
 527         int r;
 528
 529         assert(context);
 530         assert(fd >= 0);
 531
 532         r = set_ensure_allocated(&context->listen, NULL);
 533         if (r < 0) {
 534                 log_oom();
 535                 return r;
 536         }
 537
 538         r = sd_is_socket(fd, 0, SOCK_STREAM, 1);
 539         if (r < 0)
 540                 return log_error_errno(r, "Failed to determine socket type: %m");
 541         if (r == 0) {
 542                 log_error("Passed in socket is not a stream socket.");
 543                 return -EINVAL;
 544         }
 545
 546         r = fd_nonblock(fd, true);
 547         if (r < 0)
 548                 return log_error_errno(r, "Failed to mark file descriptor non-blocking: %m");
 549
 550         r = sd_event_add_io(context->event, &source, fd, EPOLLIN, accept_cb, context);
 551         if (r < 0)
 552                 return log_error_errno(r, "Failed to add event source: %m");
 553
 554         r = set_put(context->listen, source);
 555         if (r < 0) {
 556                 log_error_errno(r, "Failed to add source to set: %m");
 557                 sd_event_source_unref(source);
 558                 return r;
 559         }
 560
 561         /* Set the watcher to oneshot in case other processes are also
 562          * watching to accept(). */
 563         r = sd_event_source_set_enabled(source, SD_EVENT_ONESHOT);
 564         if (r < 0)
 565                 return log_error_errno(r, "Failed to enable oneshot mode: %m");
 566
 567         return 0;
 568 }
 569
 570 static void help(void) {
 571         printf("%1$s [HOST:PORT]\n"
 572                "%1$s [SOCKET]\n\n"
 573                "Bidirectionally proxy local sockets to another (possibly remote) socket.\n\n"
 574                "  -h --help              Show this help\n"
 575                "     --version           Show package version\n",
 576                program_invocation_short_name);
 577 }
 578
 579 static int parse_argv(int argc, char *argv[]) {
 580
 581         enum {
 582                 ARG_VERSION = 0x100,
 583                 ARG_IGNORE_ENV
 584         };
 585
 586         static const struct option options[] = {
 587                 { "help",       no_argument, NULL, 'h'           },
 588                 { "version",    no_argument, NULL, ARG_VERSION   },
 589                 {}
 590         };
 591
 592         int c;
 593
 594         assert(argc >= 0);
 595         assert(argv);
 596
 597         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 598
 599                 switch (c) {
 600
 601                 case 'h':
 602                         help();
 603                         return 0;
 604
 605                 case ARG_VERSION:
 606                         return version();
 607
 608                 case '?':
 609                         return -EINVAL;
 610
 611                 default:
 612                         assert_not_reached("Unhandled option");
 613                 }
 614
 615         if (optind >= argc) {
 616                 log_error("Not enough parameters.");
 617                 return -EINVAL;
 618         }
 619
 620         if (argc != optind+1) {
 621                 log_error("Too many parameters.");
 622                 return -EINVAL;
 623         }
 624
 625         arg_remote_host = argv[optind];
 626         return 1;
 627 }
 628
 629 int main(int argc, char *argv[]) {
 630         Context context = {};
 631         int r, n, fd;
 632
 633         log_parse_environment();
 634         log_open();
 635
 636         r = parse_argv(argc, argv);
 637         if (r <= 0)
 638                 goto finish;
 639
 640         r = sd_event_default(&context.event);
 641         if (r < 0) {
 642                 log_error_errno(r, "Failed to allocate event loop: %m");
 643                 goto finish;
 644         }
 645
 646         r = sd_resolve_default(&context.resolve);
 647         if (r < 0) {
 648                 log_error_errno(r, "Failed to allocate resolver: %m");
 649                 goto finish;
 650         }
 651
 652         r = sd_resolve_attach_event(context.resolve, context.event, 0);
 653         if (r < 0) {
 654                 log_error_errno(r, "Failed to attach resolver: %m");
 655                 goto finish;
 656         }
 657
 658         sd_event_set_watchdog(context.event, true);
 659
 660         n = sd_listen_fds(1);
 661         if (n < 0) {
 662                 log_error("Failed to receive sockets from parent.");
 663                 r = n;
 664                 goto finish;
 665         } else if (n == 0) {
 666                 log_error("Didn't get any sockets passed in.");
 667                 r = -EINVAL;
 668                 goto finish;
 669         }
 670
 671         for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
 672                 r = add_listen_socket(&context, fd);
 673                 if (r < 0)
 674                         goto finish;
 675         }
 676
 677         r = sd_event_loop(context.event);
 678         if (r < 0) {
 679                 log_error_errno(r, "Failed to run event loop: %m");
 680                 goto finish;
 681         }
 682
 683 finish:
 684         context_free(&context);
 685
 686         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 687 }