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