src/watchdog-mux.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <unistd.h>
   4 #include <fcntl.h>
   5 #include <string.h>
   6 #include <errno.h>
   7 #include <time.h>
   8 #include <sys/ioctl.h>
   9 #include <sys/types.h>
  10 #include <sys/stat.h>
  11 #include <sys/socket.h>
  12 #include <sys/un.h>
  13 #include <sys/epoll.h>
  14 #include <signal.h>
  15 #include <sys/signalfd.h>
  16
  17 #include <linux/types.h>
  18 #include <linux/watchdog.h>
  19
  20 #include <systemd/sd-daemon.h>
  21
  22 #define MY_SOCK_PATH "/run/watchdog-mux.sock"
  23 #define WD_ACTIVE_MARKER "/run/watchdog-mux.active"
  24
  25 #define LISTEN_BACKLOG 32 /* set same value in watchdog-mux.socket */
  26
  27 #define MAX_EVENTS 10
  28
  29 #define WATCHDOG_DEV "/dev/watchdog"
  30
  31 int watchdog_fd = -1;
  32 int watchdog_timeout = 10;
  33 int client_watchdog_timeout = 60;
  34 int update_watchdog = 1;
  35
  36 typedef struct {
  37     int fd;
  38     time_t time;
  39     int magic_close;
  40 } wd_client_t;
  41
  42 #define MAX_CLIENTS 100
  43
  44 static wd_client_t client_list[MAX_CLIENTS];
  45
  46 static wd_client_t *
  47 alloc_client(int fd, time_t time)
  48 {
  49     int i;
  50
  51     for (i = 0; i < MAX_CLIENTS; i++) {
  52         if (client_list[i].fd == 0) {
  53             client_list[i].fd = fd;
  54             client_list[i].time = time;
  55             client_list[i].magic_close = 0;
  56             return &client_list[i];
  57         }
  58     }
  59
  60     return NULL;
  61 }
  62
  63 static void
  64 free_client(wd_client_t *wd_client)
  65 {
  66     if (!wd_client)
  67         return;
  68
  69     wd_client->time = 0;
  70     wd_client->fd = 0;
  71     wd_client->magic_close = 0;
  72 }
  73
  74 static int
  75 active_client_count(void)
  76 {
  77     int i, count = 0;
  78
  79     for (i = 0; i < MAX_CLIENTS; i++) {
  80         if (client_list[i].fd != 0 && client_list[i].time != 0) {
  81             count++;
  82         }
  83     }
  84
  85     return count;
  86 }
  87
  88 static void
  89 watchdog_close(void)
  90 {
  91     if (watchdog_fd != -1) {
  92         if (write(watchdog_fd, "V", 1) == -1) {
  93             perror("write magic watchdog close");
  94         }
  95         if (close(watchdog_fd) == -1) {
  96             perror("write magic watchdog close");
  97         }
  98     }
  99
 100     watchdog_fd = -1;
 101 }
 102
 103 int
 104 main(void)
 105 {
 106     struct sockaddr_un my_addr, peer_addr;
 107     socklen_t peer_addr_size;
 108     struct epoll_event ev, events[MAX_EVENTS];
 109     int socket_count, listen_sock, nfds, epollfd, sigfd;
 110
 111
 112     struct stat fs;
 113
 114     if (stat(WD_ACTIVE_MARKER, &fs) == 0) {
 115         fprintf(stderr, "watchdog active - unable to restart watchdog-mux\n");
 116         exit(EXIT_FAILURE);
 117     }
 118
 119     if (stat(WATCHDOG_DEV, &fs) == -1) {
 120         system("modprobe -q softdog soft_noboot=1"); // fixme
 121     }
 122
 123     if ((watchdog_fd = open(WATCHDOG_DEV, O_WRONLY)) == -1) {
 124          perror("watchdog open");
 125          exit(EXIT_FAILURE);
 126     }
 127
 128     if (ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &watchdog_timeout) == -1) {
 129         perror("watchdog set timeout");
 130         watchdog_close();
 131         exit(EXIT_FAILURE);
 132     }
 133
 134     /* read and log watchdog identity */
 135     struct watchdog_info wdinfo;
 136     if (ioctl(watchdog_fd, WDIOC_GETSUPPORT, &wdinfo) == -1) {
 137         perror("read watchdog info");
 138         watchdog_close();
 139         exit(EXIT_FAILURE);
 140     }
 141
 142     wdinfo.identity[sizeof(wdinfo.identity) - 1] = 0; // just to be sure
 143     fprintf(stderr, "Watchdog driver '%s', version %x\n",
 144             wdinfo.identity, wdinfo.firmware_version);
 145
 146     socket_count = sd_listen_fds(0);
 147
 148     if (socket_count > 1) {
 149
 150         perror("too many file descriptors received.\n");
 151         goto err;
 152
 153     } else if (socket_count == 1) {
 154
 155         listen_sock = SD_LISTEN_FDS_START + 0;
 156
 157     } else {
 158
 159         unlink(MY_SOCK_PATH);
 160
 161         listen_sock = socket(AF_UNIX, SOCK_STREAM, 0);
 162         if (listen_sock == -1) {
 163             perror("socket create");
 164             exit(EXIT_FAILURE);
 165         }
 166
 167         memset(&my_addr, 0, sizeof(struct sockaddr_un));
 168         my_addr.sun_family = AF_UNIX;
 169         strncpy(my_addr.sun_path, MY_SOCK_PATH, sizeof(my_addr.sun_path) - 1);
 170
 171         if (bind(listen_sock, (struct sockaddr *) &my_addr,
 172                  sizeof(struct sockaddr_un)) == -1) {
 173             perror("socket bind");
 174             exit(EXIT_FAILURE);
 175         }
 176
 177         if (listen(listen_sock, LISTEN_BACKLOG) == -1) {
 178             perror("socket listen");
 179             goto err;
 180         }
 181     }
 182
 183     epollfd = epoll_create(10);
 184     if (epollfd == -1) {
 185         perror("epoll_create");
 186         goto err;
 187     }
 188
 189     ev.events = EPOLLIN;
 190     ev.data.ptr = alloc_client(listen_sock, 0);
 191     if (epoll_ctl(epollfd, EPOLL_CTL_ADD, listen_sock, &ev) == -1) {
 192         perror("epoll_ctl add listen_sock");
 193         goto err;
 194     }
 195
 196     sigset_t mask;
 197     sigemptyset(&mask);
 198     sigaddset(&mask, SIGINT);
 199     sigaddset(&mask, SIGTERM);
 200     sigaddset(&mask, SIGHUP);
 201
 202     sigprocmask(SIG_BLOCK, &mask, NULL);
 203
 204     if ((sigfd = signalfd(-1, &mask, SFD_NONBLOCK)) < 0) {
 205         perror("unable to open signalfd");
 206         goto err;
 207     }
 208
 209     ev.events = EPOLLIN;
 210     ev.data.ptr = alloc_client(sigfd, 0);
 211     if (epoll_ctl(epollfd, EPOLL_CTL_ADD, sigfd, &ev) == -1) {
 212         perror("epoll_ctl add sigfd");
 213         goto err;
 214     }
 215
 216     for (;;) {
 217         nfds = epoll_wait(epollfd, events, MAX_EVENTS, 1000);
 218         if (nfds == -1) {
 219             if (errno == EINTR)
 220                 continue;
 221
 222             perror("epoll_pwait");
 223             goto err;
 224         }
 225
 226         if (nfds == 0) { // timeout
 227
 228             // check for timeouts
 229             if (update_watchdog) {
 230                 int i;
 231                 time_t ctime = time(NULL);
 232                 for (i = 0; i < MAX_CLIENTS; i++) {
 233                     if (client_list[i].fd != 0 && client_list[i].time != 0 &&
 234                         ((ctime - client_list[i].time) > client_watchdog_timeout)) {
 235                         update_watchdog = 0;
 236                         fprintf(stderr, "client watchdog expired - disable watchdog updates\n");
 237                     }
 238                 }
 239             }
 240
 241             if (update_watchdog) {
 242                 if (ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0) == -1) {
 243                     perror("watchdog update failed");
 244                 }
 245             }
 246
 247             continue;
 248         }
 249
 250         if (!update_watchdog)
 251             break;
 252
 253         int terminate = 0;
 254
 255         int n;
 256         for (n = 0; n < nfds; ++n) {
 257             wd_client_t *wd_client = events[n].data.ptr;
 258             if (wd_client->fd == listen_sock) {
 259                 int conn_sock = accept(listen_sock, (struct sockaddr *) &peer_addr, &peer_addr_size);
 260                 if (conn_sock == -1) {
 261                     perror("accept");
 262                     goto err; // fixme
 263                 }
 264                 if (fcntl(conn_sock, F_SETFL, O_NONBLOCK) == -1) {
 265                     perror("setnonblocking");
 266                     goto err; // fixme
 267                 }
 268
 269                 wd_client_t *new_client = alloc_client(conn_sock, time(NULL));
 270                 if (new_client == NULL) {
 271                     fprintf(stderr, "unable to alloc wd_client structure\n");
 272                     goto err; // fixme;
 273                 }
 274
 275                 mkdir(WD_ACTIVE_MARKER, 0600);
 276
 277                 ev.events = EPOLLIN;
 278                 ev.data.ptr = new_client;
 279                 if (epoll_ctl(epollfd, EPOLL_CTL_ADD, conn_sock, &ev) == -1) {
 280                     perror("epoll_ctl: add conn_sock");
 281                     goto err; // fixme
 282                 }
 283             } else if (wd_client->fd == sigfd) {
 284
 285                 /* signal handling */
 286
 287                 int rv = 0;
 288                 struct signalfd_siginfo si;
 289
 290                 if ((rv = read(sigfd, &si, sizeof(si))) && rv >= 0) {
 291                     if (si.ssi_signo == SIGHUP) {
 292                         perror("got SIGHUP - ignored");
 293                     } else {
 294                         terminate = 1;
 295                         fprintf(stderr, "got terminate request\n");
 296                     }
 297                 }
 298
 299             } else {
 300                 char buf[4096];
 301                 int cfd = wd_client->fd;
 302
 303                 ssize_t bytes = read(cfd, buf, sizeof(buf));
 304                 if (bytes == -1) {
 305                     perror("read");
 306                     goto err; // fixme
 307                 } else if (bytes > 0) {
 308                     int i;
 309                     for (i = 0; i < bytes; i++) {
 310                         if (buf[i] == 'V') {
 311                             wd_client->magic_close = 1;
 312                         } else {
 313                             wd_client->magic_close = 0;
 314                         }
 315                     }
 316                     wd_client->time = time(NULL);
 317                 } else {
 318                     if (events[n].events & EPOLLHUP || events[n].events & EPOLLERR) {
 319                         //printf("GOT %016x event\n", events[n].events);
 320                         if (epoll_ctl(epollfd, EPOLL_CTL_DEL, cfd, NULL) == -1) {
 321                             perror("epoll_ctl: del conn_sock");
 322                             goto err; // fixme
 323                         }
 324                         if (close(cfd) == -1) {
 325                             perror("close conn_sock");
 326                             goto err; // fixme
 327                         }
 328
 329                         if (!wd_client->magic_close) {
 330                             fprintf(stderr, "client did not stop watchdog - disable watchdog updates\n");
 331                             update_watchdog = 0;
 332                         } else {
 333                             free_client(wd_client);
 334                         }
 335
 336                         if (!active_client_count()) {
 337                             rmdir(WD_ACTIVE_MARKER);
 338                         }
 339                     }
 340                 }
 341             }
 342         }
 343         if (terminate)
 344             break;
 345     }
 346
 347     int active_count = active_client_count();
 348     if (active_count > 0) {
 349         fprintf(stderr, "exit watchdog-mux with active connections\n");
 350     } else {
 351         fprintf(stderr, "clean exit\n");
 352         watchdog_close();
 353     }
 354
 355     unlink(MY_SOCK_PATH);
 356     exit(EXIT_SUCCESS);
 357
 358 err:
 359     unlink(MY_SOCK_PATH);
 360     exit(EXIT_FAILURE);
 361 }