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