src/stdio-bridge/stdio-bridge.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <getopt.h>
   5 #include <stddef.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8
   9 #include "sd-bus.h"
  10 #include "sd-daemon.h"
  11
  12 #include "alloc-util.h"
  13 #include "build.h"
  14 #include "bus-internal.h"
  15 #include "bus-util.h"
  16 #include "errno-util.h"
  17 #include "io-util.h"
  18 #include "log.h"
  19 #include "main-func.h"
  20 #include "version.h"
  21
  22 #define DEFAULT_BUS_PATH "unix:path=/run/dbus/system_bus_socket"
  23
  24 static const char *arg_bus_path = DEFAULT_BUS_PATH;
  25 static BusTransport arg_transport = BUS_TRANSPORT_LOCAL;
  26 static RuntimeScope arg_runtime_scope = RUNTIME_SCOPE_SYSTEM;
  27
  28 static int help(void) {
  29         printf("%s [OPTIONS...]\n\n"
  30                "Forward messages between a pipe or socket and a D-Bus bus.\n\n"
  31                "  -h --help              Show this help\n"
  32                "     --version           Show package version\n"
  33                "  -p --bus-path=PATH     Path to the bus address (default: %s)\n"
  34                "     --system            Connect to system bus\n"
  35                "     --user              Connect to user bus\n"
  36                "  -M --machine=CONTAINER Name of local container to connect to\n",
  37                program_invocation_short_name, DEFAULT_BUS_PATH);
  38
  39         return 0;
  40 }
  41
  42 static int parse_argv(int argc, char *argv[]) {
  43         enum {
  44                 ARG_VERSION = 0x100,
  45                 ARG_MACHINE,
  46                 ARG_USER,
  47                 ARG_SYSTEM,
  48         };
  49
  50         static const struct option options[] = {
  51                 { "help",            no_argument,       NULL, 'h'         },
  52                 { "version",         no_argument,       NULL, ARG_VERSION },
  53                 { "bus-path",        required_argument, NULL, 'p'         },
  54                 { "user",            no_argument,       NULL, ARG_USER    },
  55                 { "system",          no_argument,       NULL, ARG_SYSTEM  },
  56                 { "machine",         required_argument, NULL, 'M'         },
  57                 {},
  58         };
  59
  60         int c;
  61
  62         assert(argc >= 0);
  63         assert(argv);
  64
  65         while ((c = getopt_long(argc, argv, "hp:M:", options, NULL)) >= 0)
  66
  67                 switch (c) {
  68
  69                 case 'h':
  70                         return help();
  71
  72                 case ARG_VERSION:
  73                         return version();
  74
  75                 case ARG_USER:
  76                         arg_runtime_scope = RUNTIME_SCOPE_USER;
  77                         break;
  78
  79                 case ARG_SYSTEM:
  80                         arg_runtime_scope = RUNTIME_SCOPE_SYSTEM;
  81                         break;
  82
  83                 case 'p':
  84                         arg_bus_path = optarg;
  85                         break;
  86
  87                 case 'M':
  88                         arg_bus_path = optarg;
  89                         arg_transport = BUS_TRANSPORT_MACHINE;
  90                         break;
  91
  92                 case '?':
  93                         return -EINVAL;
  94
  95                 default:
  96                         return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
  97                                                "Unknown option code %c", c);
  98                 }
  99
 100         return 1;
 101 }
 102
 103 static int run(int argc, char *argv[]) {
 104         _cleanup_(sd_bus_flush_close_unrefp) sd_bus *a = NULL, *b = NULL;
 105         sd_id128_t server_id;
 106         bool is_unix;
 107         int r, in_fd, out_fd;
 108
 109         log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
 110         log_parse_environment();
 111         log_open();
 112
 113         r = parse_argv(argc, argv);
 114         if (r <= 0)
 115                 return r;
 116
 117         r = sd_listen_fds(0);
 118         if (r == 0) {
 119                 in_fd = STDIN_FILENO;
 120                 out_fd = STDOUT_FILENO;
 121         } else if (r == 1) {
 122                 in_fd = SD_LISTEN_FDS_START;
 123                 out_fd = SD_LISTEN_FDS_START;
 124         } else
 125                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "More than one file descriptor was passed.");
 126
 127         is_unix =
 128                 sd_is_socket(in_fd, AF_UNIX, 0, 0) > 0 &&
 129                 sd_is_socket(out_fd, AF_UNIX, 0, 0) > 0;
 130
 131         r = sd_bus_new(&a);
 132         if (r < 0)
 133                 return log_error_errno(r, "Failed to allocate bus: %m");
 134
 135         if (arg_transport == BUS_TRANSPORT_MACHINE)
 136                 r = bus_set_address_machine(a, arg_runtime_scope, arg_bus_path);
 137         else
 138                 r = sd_bus_set_address(a, arg_bus_path);
 139         if (r < 0)
 140                 return log_error_errno(r, "Failed to set address to connect to: %m");
 141
 142         r = sd_bus_negotiate_fds(a, is_unix);
 143         if (r < 0)
 144                 return log_error_errno(r, "Failed to set FD negotiation: %m");
 145
 146         r = sd_bus_start(a);
 147         if (r < 0)
 148                 return log_error_errno(r, "Failed to start bus client: %m");
 149
 150         r = sd_bus_get_bus_id(a, &server_id);
 151         if (r < 0)
 152                 return log_error_errno(r, "Failed to get server ID: %m");
 153
 154         r = sd_bus_new(&b);
 155         if (r < 0)
 156                 return log_error_errno(r, "Failed to allocate bus: %m");
 157
 158         r = sd_bus_set_fd(b, in_fd, out_fd);
 159         if (r < 0)
 160                 return log_error_errno(r, "Failed to set fds: %m");
 161
 162         r = sd_bus_set_server(b, 1, server_id);
 163         if (r < 0)
 164                 return log_error_errno(r, "Failed to set server mode: %m");
 165
 166         r = sd_bus_negotiate_fds(b, is_unix);
 167         if (r < 0)
 168                 return log_error_errno(r, "Failed to set FD negotiation: %m");
 169
 170         r = sd_bus_set_anonymous(b, true);
 171         if (r < 0)
 172                 return log_error_errno(r, "Failed to set anonymous authentication: %m");
 173
 174         r = sd_bus_start(b);
 175         if (r < 0)
 176                 return log_error_errno(r, "Failed to start bus client: %m");
 177
 178         for (;;) {
 179                 _cleanup_(sd_bus_message_unrefp) sd_bus_message *m = NULL;
 180                 int events_a, events_b, fd;
 181                 usec_t timeout_a, timeout_b, t;
 182
 183                 assert_cc(sizeof(usec_t) == sizeof(uint64_t));
 184
 185                 r = sd_bus_process(a, &m);
 186                 if (r < 0)
 187                         return log_error_errno(r, "Failed to process bus a: %m");
 188
 189                 if (m) {
 190                         r = sd_bus_send(b, m, NULL);
 191                         if (r < 0)
 192                                 return log_error_errno(r, "Failed to send message: %m");
 193                 }
 194
 195                 if (r > 0)
 196                         continue;
 197
 198                 r = sd_bus_process(b, &m);
 199                 if (r < 0) {
 200                         /* treat 'connection reset by peer' as clean exit condition */
 201                         if (ERRNO_IS_DISCONNECT(r))
 202                                 return 0;
 203
 204                         return log_error_errno(r, "Failed to process bus: %m");
 205                 }
 206
 207                 if (m) {
 208                         r = sd_bus_send(a, m, NULL);
 209                         if (r < 0)
 210                                 return log_error_errno(r, "Failed to send message: %m");
 211                 }
 212
 213                 if (r > 0)
 214                         continue;
 215
 216                 fd = sd_bus_get_fd(a);
 217                 if (fd < 0)
 218                         return log_error_errno(fd, "Failed to get fd: %m");
 219
 220                 events_a = sd_bus_get_events(a);
 221                 if (events_a < 0)
 222                         return log_error_errno(events_a, "Failed to get events mask: %m");
 223
 224                 r = sd_bus_get_timeout(a, &timeout_a);
 225                 if (r < 0)
 226                         return log_error_errno(r, "Failed to get timeout: %m");
 227
 228                 events_b = sd_bus_get_events(b);
 229                 if (events_b < 0)
 230                         return log_error_errno(events_b, "Failed to get events mask: %m");
 231
 232                 r = sd_bus_get_timeout(b, &timeout_b);
 233                 if (r < 0)
 234                         return log_error_errno(r, "Failed to get timeout: %m");
 235
 236                 t = usec_sub_unsigned(MIN(timeout_a, timeout_b), now(CLOCK_MONOTONIC));
 237
 238                 struct pollfd p[3] = {
 239                         { .fd = fd,            .events = events_a           },
 240                         { .fd = STDIN_FILENO,  .events = events_b & POLLIN  },
 241                         { .fd = STDOUT_FILENO, .events = events_b & POLLOUT },
 242                 };
 243
 244                 r = ppoll_usec(p, ELEMENTSOF(p), t);
 245                 if (r < 0) {
 246                         if (ERRNO_IS_TRANSIENT(r)) /* don't be bothered by signals, i.e. EINTR */
 247                                 continue;
 248                         return log_error_errno(r, "ppoll() failed: %m");
 249                 }
 250         }
 251
 252         return 0;
 253 }
 254
 255 DEFINE_MAIN_FUNCTION(run);