usr.sbin/rpc.statd/file.c

   1 /*
   2  * Copyright (c) 1995
   3  *      A.R. Gordon (andrew.gordon@net-tel.co.uk).  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed for the FreeBSD project
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY ANDREW GORDON AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <err.h>
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40 #include <sys/types.h>
  41 #include <sys/mman.h>           /* For mmap()                           */
  42 #include <rpc/rpc.h>
  43 #include <syslog.h>
  44
  45 #include "statd.h"
  46
  47 FileLayout *status_info;        /* Pointer to the mmap()ed status file  */
  48 static int status_fd;           /* File descriptor for the open file    */
  49 static off_t status_file_len;   /* Current on-disc length of file       */
  50
  51 /* sync_file --------------------------------------------------------------- */
  52 /*
  53    Purpose:     Packaged call of msync() to flush changes to mmap()ed file
  54    Returns:     Nothing.  Errors to syslog.
  55 */
  56
  57 void
  58 sync_file(void)
  59 {
  60   if (msync((void *)status_info, 0, 0) < 0)
  61   {
  62     syslog(LOG_ERR, "msync() failed: %s", strerror(errno));
  63   }
  64 }
  65
  66 /* find_host -------------------------------------------------------------- */
  67 /*
  68    Purpose:     Find the entry in the status file for a given host
  69    Returns:     Pointer to that entry in the mmap() region, or NULL.
  70    Notes:       Also creates entries if requested.
  71                 Failure to create also returns NULL.
  72 */
  73
  74 HostInfo *
  75 find_host(char *hostname, int create)
  76 {
  77   HostInfo *hp;
  78   HostInfo *spare_slot = NULL;
  79   HostInfo *result = NULL;
  80   int i;
  81
  82   for (i = 0, hp = status_info->hosts; i < status_info->noOfHosts; i++, hp++)
  83   {
  84     if (!strncasecmp(hostname, hp->hostname, SM_MAXSTRLEN))
  85     {
  86       result = hp;
  87       break;
  88     }
  89     if (!spare_slot && !hp->monList && !hp->notifyReqd)
  90       spare_slot = hp;
  91   }
  92
  93   /* Return if entry found, or if not asked to create one.              */
  94   if (result || !create) return (result);
  95
  96   /* Now create an entry, using the spare slot if one was found or      */
  97   /* adding to the end of the list otherwise, extending file if reqd    */
  98   if (!spare_slot)
  99   {
 100     off_t desired_size;
 101     spare_slot = &status_info->hosts[status_info->noOfHosts];
 102     desired_size = ((char*)spare_slot - (char*)status_info) + sizeof(HostInfo);
 103     if (desired_size > status_file_len)
 104     {
 105       /* Extend file by writing 1 byte of junk at the desired end pos   */
 106       lseek(status_fd, desired_size - 1, SEEK_SET);
 107       i = write(status_fd, &i, 1);
 108       if (i < 1)
 109       {
 110         syslog(LOG_ERR, "Unable to extend status file");
 111         return (NULL);
 112       }
 113       status_file_len = desired_size;
 114     }
 115     status_info->noOfHosts++;
 116   }
 117
 118   /* Initialise the spare slot that has been found/created              */
 119   /* Note that we do not msync(), since the caller is presumed to be    */
 120   /* about to modify the entry further                                  */
 121   memset(spare_slot, 0, sizeof(HostInfo));
 122   strncpy(spare_slot->hostname, hostname, SM_MAXSTRLEN);
 123   return (spare_slot);
 124 }
 125
 126 /* init_file -------------------------------------------------------------- */
 127 /*
 128    Purpose:     Open file, create if necessary, initialise it.
 129    Returns:     Nothing - exits on error
 130    Notes:       Called before process becomes daemon, hence logs to
 131                 stderr rather than syslog.
 132                 Opens the file, then mmap()s it for ease of access.
 133                 Also performs initial clean-up of the file, zeroing
 134                 monitor list pointers, setting the notifyReqd flag in
 135                 all hosts that had a monitor list, and incrementing
 136                 the state number to the next even value.
 137 */
 138
 139 void
 140 init_file(const char *filename)
 141 {
 142   int new_file = FALSE;
 143   char buf[HEADER_LEN];
 144   int i;
 145
 146   /* try to open existing file - if not present, create one             */
 147   status_fd = open(filename, O_RDWR);
 148   if ((status_fd < 0) && (errno == ENOENT))
 149   {
 150     status_fd = open(filename, O_RDWR | O_CREAT, 0644);
 151     new_file = TRUE;
 152   }
 153   if (status_fd < 0)
 154     errx(1, "unable to open status file %s", filename);
 155
 156   /* File now open.  mmap() it, with a generous size to allow for       */
 157   /* later growth, where we will extend the file but not re-map it.     */
 158   status_info = (FileLayout *)
 159     mmap(NULL, 0x10000000, PROT_READ | PROT_WRITE, MAP_SHARED, status_fd, 0);
 160
 161   if (status_info == (FileLayout *) MAP_FAILED)
 162     warn("unable to mmap() status file");
 163
 164   status_file_len = lseek(status_fd, 0L, SEEK_END);
 165
 166   /* If the file was not newly created, validate the contents, and if   */
 167   /* defective, re-create from scratch.                                 */
 168   if (!new_file)
 169   {
 170     if ((status_file_len < (off_t)HEADER_LEN) || (status_file_len
 171       < (off_t)(HEADER_LEN + sizeof(HostInfo) * status_info->noOfHosts)) )
 172     {
 173       warnx("status file is corrupt");
 174       new_file = TRUE;
 175     }
 176   }
 177
 178   /* Initialisation of a new, empty file.                               */
 179   if (new_file)
 180   {
 181     memset(buf, 0, sizeof(buf));
 182     lseek(status_fd, 0L, SEEK_SET);
 183     write(status_fd, buf, HEADER_LEN);
 184     status_file_len = HEADER_LEN;
 185   }
 186   else
 187   {
 188     /* Clean-up of existing file - monitored hosts will have a pointer  */
 189     /* to a list of clients, which refers to memory in the previous     */
 190     /* incarnation of the program and so are meaningless now.  These    */
 191     /* pointers are zeroed and the fact that the host was previously    */
 192     /* monitored is recorded by setting the notifyReqd flag, which will */
 193     /* in due course cause a SM_NOTIFY to be sent.                      */
 194     /* Note that if we crash twice in quick succession, some hosts may  */
 195     /* already have notifyReqd set, where we didn't manage to notify    */
 196     /* them before the second crash occurred.                           */
 197     for (i = 0; i < status_info->noOfHosts; i++)
 198     {
 199       HostInfo *this_host = &status_info->hosts[i];
 200
 201       if (this_host->monList)
 202       {
 203         this_host->notifyReqd = TRUE;
 204         this_host->monList = NULL;
 205       }
 206     }
 207     /* Select the next higher even number for the state counter         */
 208     status_info->ourState = (status_info->ourState + 2) & 0xfffffffe;
 209 /*???????******/ status_info->ourState++;
 210   }
 211 }
 212
 213 /* notify_one_host --------------------------------------------------------- */
 214 /*
 215    Purpose:     Perform SM_NOTIFY procedure at specified host
 216    Returns:     TRUE if success, FALSE if failed.
 217 */
 218
 219 static int
 220 notify_one_host(char *hostname)
 221 {
 222   struct timeval timeout = { 20, 0 };   /* 20 secs timeout              */
 223   CLIENT *cli;
 224   char dummy;
 225   stat_chge arg;
 226   char our_hostname[SM_MAXSTRLEN+1];
 227
 228   gethostname(our_hostname, sizeof(our_hostname));
 229   our_hostname[SM_MAXSTRLEN] = '\0';
 230   arg.mon_name = our_hostname;
 231   arg.state = status_info->ourState;
 232
 233   if (debug) syslog (LOG_DEBUG, "Sending SM_NOTIFY to host %s from %s", hostname, our_hostname);
 234
 235   cli = clnt_create(hostname, SM_PROG, SM_VERS, "udp");
 236   if (!cli)
 237   {
 238     syslog(LOG_ERR, "Failed to contact host %s%s", hostname,
 239       clnt_spcreateerror(""));
 240     return (FALSE);
 241   }
 242
 243   if (clnt_call(cli, SM_NOTIFY, (xdrproc_t)xdr_stat_chge, &arg,
 244       (xdrproc_t)xdr_void, &dummy, timeout)
 245     != RPC_SUCCESS)
 246   {
 247     syslog(LOG_ERR, "Failed to contact rpc.statd at host %s", hostname);
 248     clnt_destroy(cli);
 249     return (FALSE);
 250   }
 251
 252   clnt_destroy(cli);
 253   return (TRUE);
 254 }
 255
 256 /* notify_hosts ------------------------------------------------------------ */
 257 /*
 258    Purpose:     Send SM_NOTIFY to all hosts marked as requiring it
 259    Returns:     Nothing, immediately - forks a process to do the work.
 260    Notes:       Does nothing if there are no monitored hosts.
 261                 Called after all the initialisation has been done -
 262                 logs to syslog.
 263 */
 264
 265 void
 266 notify_hosts(void)
 267 {
 268   int i;
 269   int attempts;
 270   int work_to_do = FALSE;
 271   HostInfo *hp;
 272   pid_t pid;
 273
 274   /* First check if there is in fact any work to do.                    */
 275   for (i = status_info->noOfHosts, hp = status_info->hosts; i ; i--, hp++)
 276   {
 277     if (hp->notifyReqd)
 278     {
 279       work_to_do = TRUE;
 280       break;
 281     }
 282   }
 283
 284   if (!work_to_do) return;      /* No work found                        */
 285
 286   pid = fork();
 287   if (pid == -1)
 288   {
 289     syslog(LOG_ERR, "Unable to fork notify process - %s", strerror(errno));
 290     return;
 291   }
 292   if (pid) return;
 293
 294   /* Here in the child process.  We continue until all the hosts marked */
 295   /* as requiring notification have been duly notified.                 */
 296   /* If one of the initial attempts fails, we sleep for a while and     */
 297   /* have another go.  This is necessary because when we have crashed,  */
 298   /* (eg. a power outage) it is quite possible that we won't be able to */
 299   /* contact all monitored hosts immediately on restart, either because */
 300   /* they crashed too and take longer to come up (in which case the     */
 301   /* notification isn't really required), or more importantly if some   */
 302   /* router etc. needed to reach the monitored host has not come back   */
 303   /* up yet.  In this case, we will be a bit late in re-establishing    */
 304   /* locks (after the grace period) but that is the best we can do.     */
 305   /* We try 10 times at 5 sec intervals, 10 more times at 1 minute      */
 306   /* intervals, then 24 more times at hourly intervals, finally         */
 307   /* giving up altogether if the host hasn't come back to life after    */
 308   /* 24 hours.                                                          */
 309
 310   for (attempts = 0; attempts < 44; attempts++)
 311   {
 312     work_to_do = FALSE;         /* Unless anything fails                */
 313     for (i = status_info->noOfHosts, hp = status_info->hosts; i ; i--, hp++)
 314     {
 315       if (hp->notifyReqd)
 316       {
 317         if (notify_one_host(hp->hostname))
 318         {
 319           hp->notifyReqd = FALSE;
 320           sync_file();
 321         }
 322         else work_to_do = TRUE;
 323       }
 324     }
 325     if (!work_to_do) break;
 326     if (attempts < 10) sleep(5);
 327     else if (attempts < 20) sleep(60);
 328     else sleep(60*60);
 329   }
 330   exit(0);
 331 }
 332
 333