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