src/stdio-bridge/stdio-bridge.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <getopt.h>
   5 #include <poll.h>
   6 #include <stddef.h>
   7 #include <string.h>
   8 #include <unistd.h>
   9
  10 #include "sd-bus.h"
  11 #include "sd-daemon.h"
  12
  13 #include "alloc-util.h"
  14 #include "bus-internal.h"
  15 #include "bus-util.h"
  16 #include "build.h"
  17 #include "log.h"
  18 #include "util.h"
  19
  20 #define DEFAULT_BUS_PATH "unix:path=/run/dbus/system_bus_socket"
  21
  22 static const char *arg_bus_path = DEFAULT_BUS_PATH;
  23 static BusTransport arg_transport = BUS_TRANSPORT_LOCAL;
  24
  25 static int help(void) {
  26
  27         printf("%s [OPTIONS...]\n\n"
  28                "STDIO or socket-activatable proxy to a given DBus endpoint.\n\n"
  29                "  -h --help              Show this help\n"
  30                "     --version           Show package version\n"
  31                "  -p --bus-path=PATH     Path to the kernel bus (default: %s)\n"
  32                "  -M --machine=MACHINE   Name of machine to connect to\n",
  33                program_invocation_short_name, DEFAULT_BUS_PATH);
  34
  35         return 0;
  36 }
  37
  38 static int parse_argv(int argc, char *argv[]) {
  39
  40         enum {
  41                 ARG_VERSION = 0x100,
  42                 ARG_MACHINE,
  43         };
  44
  45         static const struct option options[] = {
  46                 { "help",            no_argument,       NULL, 'h'         },
  47                 { "version",         no_argument,       NULL, ARG_VERSION },
  48                 { "bus-path",        required_argument, NULL, 'p'         },
  49                 { "machine",         required_argument, NULL, 'M'         },
  50                 {},
  51         };
  52
  53         int c;
  54
  55         assert(argc >= 0);
  56         assert(argv);
  57
  58         while ((c = getopt_long(argc, argv, "hsup:", options, NULL)) >= 0) {
  59
  60                 switch (c) {
  61
  62                 case 'h':
  63                         help();
  64                         return 0;
  65
  66                 case ARG_VERSION:
  67                         return version();
  68
  69                 case '?':
  70                         return -EINVAL;
  71
  72                 case 'p':
  73                         arg_bus_path = optarg;
  74
  75                         break;
  76
  77                 case 'M':
  78                         arg_bus_path = optarg;
  79
  80                         arg_transport = BUS_TRANSPORT_MACHINE;
  81
  82                         break;
  83                 default:
  84                         log_error("Unknown option code %c", c);
  85                         return -EINVAL;
  86                 }
  87         }
  88
  89         return 1;
  90 }
  91
  92 int main(int argc, char *argv[]) {
  93         _cleanup_(sd_bus_unrefp) sd_bus *a = NULL, *b = NULL;
  94         sd_id128_t server_id;
  95         bool is_unix;
  96         int r, in_fd, out_fd;
  97
  98         log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
  99         log_parse_environment();
 100         log_open();
 101
 102         r = parse_argv(argc, argv);
 103         if (r <= 0)
 104                 goto finish;
 105
 106         r = sd_listen_fds(0);
 107         if (r == 0) {
 108                 in_fd = STDIN_FILENO;
 109                 out_fd = STDOUT_FILENO;
 110         } else if (r == 1) {
 111                 in_fd = SD_LISTEN_FDS_START;
 112                 out_fd = SD_LISTEN_FDS_START;
 113         } else {
 114                 log_error("Illegal number of file descriptors passed.");
 115                 goto finish;
 116         }
 117
 118         is_unix =
 119                 sd_is_socket(in_fd, AF_UNIX, 0, 0) > 0 &&
 120                 sd_is_socket(out_fd, AF_UNIX, 0, 0) > 0;
 121
 122         r = sd_bus_new(&a);
 123         if (r < 0) {
 124                 log_error_errno(r, "Failed to allocate bus: %m");
 125                 goto finish;
 126         }
 127
 128         if (arg_transport == BUS_TRANSPORT_MACHINE)
 129                 r = bus_set_address_system_machine(a, arg_bus_path);
 130         else
 131                 r = sd_bus_set_address(a, arg_bus_path);
 132         if (r < 0) {
 133                 log_error_errno(r, "Failed to set address to connect to: %m");
 134                 goto finish;
 135         }
 136
 137         r = sd_bus_negotiate_fds(a, is_unix);
 138         if (r < 0) {
 139                 log_error_errno(r, "Failed to set FD negotiation: %m");
 140                 goto finish;
 141         }
 142
 143         r = sd_bus_start(a);
 144         if (r < 0) {
 145                 log_error_errno(r, "Failed to start bus client: %m");
 146                 goto finish;
 147         }
 148
 149         r = sd_bus_get_bus_id(a, &server_id);
 150         if (r < 0) {
 151                 log_error_errno(r, "Failed to get server ID: %m");
 152                 goto finish;
 153         }
 154
 155         r = sd_bus_new(&b);
 156         if (r < 0) {
 157                 log_error_errno(r, "Failed to allocate bus: %m");
 158                 goto finish;
 159         }
 160
 161         r = sd_bus_set_fd(b, in_fd, out_fd);
 162         if (r < 0) {
 163                 log_error_errno(r, "Failed to set fds: %m");
 164                 goto finish;
 165         }
 166
 167         r = sd_bus_set_server(b, 1, server_id);
 168         if (r < 0) {
 169                 log_error_errno(r, "Failed to set server mode: %m");
 170                 goto finish;
 171         }
 172
 173         r = sd_bus_negotiate_fds(b, is_unix);
 174         if (r < 0) {
 175                 log_error_errno(r, "Failed to set FD negotiation: %m");
 176                 goto finish;
 177         }
 178
 179         r = sd_bus_set_anonymous(b, true);
 180         if (r < 0) {
 181                 log_error_errno(r, "Failed to set anonymous authentication: %m");
 182                 goto finish;
 183         }
 184
 185         r = sd_bus_start(b);
 186         if (r < 0) {
 187                 log_error_errno(r, "Failed to start bus client: %m");
 188                 goto finish;
 189         }
 190
 191         for (;;) {
 192                 _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 193                 int events_a, events_b, fd;
 194                 uint64_t timeout_a, timeout_b, t;
 195                 struct timespec _ts, *ts;
 196
 197                 r = sd_bus_process(a, &m);
 198                 if (r < 0) {
 199                         log_error_errno(r, "Failed to process bus a: %m");
 200                         goto finish;
 201                 }
 202
 203                 if (m) {
 204                         r = sd_bus_send(b, m, NULL);
 205                         if (r < 0) {
 206                                 log_error_errno(r, "Failed to send message: %m");
 207                                 goto finish;
 208                         }
 209                 }
 210
 211                 if (r > 0)
 212                         continue;
 213
 214                 r = sd_bus_process(b, &m);
 215                 if (r < 0) {
 216                         /* treat 'connection reset by peer' as clean exit condition */
 217                         if (r == -ECONNRESET)
 218                                 r = 0;
 219
 220                         goto finish;
 221                 }
 222
 223                 if (m) {
 224                         r = sd_bus_send(a, m, NULL);
 225                         if (r < 0) {
 226                                 log_error_errno(r, "Failed to send message: %m");
 227                                 goto finish;
 228                         }
 229                 }
 230
 231                 if (r > 0)
 232                         continue;
 233
 234                 fd = sd_bus_get_fd(a);
 235                 if (fd < 0) {
 236                         r = fd;
 237                         log_error_errno(r, "Failed to get fd: %m");
 238                         goto finish;
 239                 }
 240
 241                 events_a = sd_bus_get_events(a);
 242                 if (events_a < 0) {
 243                         r = events_a;
 244                         log_error_errno(r, "Failed to get events mask: %m");
 245                         goto finish;
 246                 }
 247
 248                 r = sd_bus_get_timeout(a, &timeout_a);
 249                 if (r < 0) {
 250                         log_error_errno(r, "Failed to get timeout: %m");
 251                         goto finish;
 252                 }
 253
 254                 events_b = sd_bus_get_events(b);
 255                 if (events_b < 0) {
 256                         r = events_b;
 257                         log_error_errno(r, "Failed to get events mask: %m");
 258                         goto finish;
 259                 }
 260
 261                 r = sd_bus_get_timeout(b, &timeout_b);
 262                 if (r < 0) {
 263                         log_error_errno(r, "Failed to get timeout: %m");
 264                         goto finish;
 265                 }
 266
 267                 t = timeout_a;
 268                 if (t == (uint64_t) -1 || (timeout_b != (uint64_t) -1 && timeout_b < timeout_a))
 269                         t = timeout_b;
 270
 271                 if (t == (uint64_t) -1)
 272                         ts = NULL;
 273                 else {
 274                         usec_t nw;
 275
 276                         nw = now(CLOCK_MONOTONIC);
 277                         if (t > nw)
 278                                 t -= nw;
 279                         else
 280                                 t = 0;
 281
 282                         ts = timespec_store(&_ts, t);
 283                 }
 284
 285                 {
 286                         struct pollfd p[3] = {
 287                                 {.fd = fd,            .events = events_a, },
 288                                 {.fd = STDIN_FILENO,  .events = events_b & POLLIN, },
 289                                 {.fd = STDOUT_FILENO, .events = events_b & POLLOUT, }};
 290
 291                         r = ppoll(p, ELEMENTSOF(p), ts, NULL);
 292                 }
 293                 if (r < 0) {
 294                         log_error_errno(errno, "ppoll() failed: %m");
 295                         goto finish;
 296                 }
 297         }
 298
 299 finish:
 300         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 301 }