Add --dhcp-hostsdir config option.

CHANGELOG

@@ -54,6 +54,11 @@ version 2.73
 	    address. (IPv6 addresses are scoped, so this is allowed.)
 	    Thanks to Cory Benfield for help with this.
 
+	    Add --dhcp-hostsdir. This allows addition of new host
+	    configurations to a running dnsmasq instance much more 
+	    cheaply than having dnsmasq re-read all its existing
+	    configuration each time. 
+	
 	
 version 2.72
             Add ra-advrouter mode, for RFC-3775 mobile IPv6 support.

man/dnsmasq.8

@@ -977,6 +977,15 @@ is given, then read all the files contained in that directory. The advantage of
 using this option is the same as for --dhcp-hostsfile: the
 dhcp-optsfile will be re-read when dnsmasq receives SIGHUP. Note that
 it is possible to encode the information in a
+.TP
+.B --dhcp-hostsdir=<path>
+This is exactly equivalent to dhcp-hostfile, except for the following. The path MUST be a
+directory, and not an individual file. Changed or new files within
+the directory are read automatically, without the need to send SIGHUP.
+If a file is deleted for changed after it has been read by dnsmasq, then the
+host record it contained will remain until dnsmasq recieves a SIGHUP, or 
+is restarted; ie host records are only added dynamically.
+.TP
 .B --dhcp-boot
 flag as DHCP options, using the options names bootfile-name,
 server-ip-address and tftp-server. This allows these to be included

src/dnsmasq.c

@@ -142,6 +142,9 @@ int main (int argc, char **argv)
       set_option_bool(OPT_NOWILD);
       reset_option_bool(OPT_CLEVERBIND);
     }
+
+  if (daemon->inotify_hosts)
+    die(_("dhcp-hostsdir not supported on this platform"), NULL, EC_BADCONF);
 #endif
   
   if (option_bool(OPT_DNSSEC_VALID))
@@ -316,12 +319,15 @@ int main (int argc, char **argv)
 #ifdef HAVE_DNSSEC
       blockdata_init();
 #endif
+    }
 
 #ifdef HAVE_LINUX_NETWORK
-      if (!option_bool(OPT_NO_POLL))
+  if ((!option_bool(OPT_NO_POLL) && daemon->port != 0) ||
+      daemon->dhcp || daemon->doing_dhcp6)
     inotify_dnsmasq_init();
+  else
+    daemon->inotifyfd = -1;
 #endif
-    }
        
   if (option_bool(OPT_DBUS))
 #ifdef HAVE_DBUS
@@ -870,7 +876,7 @@ int main (int argc, char **argv)
 #if defined(HAVE_LINUX_NETWORK)
       FD_SET(daemon->netlinkfd, &rset);
       bump_maxfd(daemon->netlinkfd, &maxfd);
-      if (daemon->port != 0 && !option_bool(OPT_NO_POLL))
+      if (daemon->inotifyfd != -1)
 	{
 	  FD_SET(daemon->inotifyfd, &rset);
 	  bump_maxfd(daemon->inotifyfd, &maxfd);
@@ -943,8 +949,11 @@ int main (int argc, char **argv)
 #endif
 
 #ifdef HAVE_LINUX_NETWORK
-      if (daemon->port != 0 && !option_bool(OPT_NO_POLL) && FD_ISSET(daemon->inotifyfd, &rset) && inotify_check())
+      if  (daemon->inotifyfd != -1 && FD_ISSET(daemon->inotifyfd, &rset) && inotify_check(now))
+	{
+	  if (daemon->port != 0 && !option_bool(OPT_NO_POLL))
 	    poll_resolv(1, 1, now);
+	} 	  
 #else
       /* Check for changes to resolv files once per second max. */
       /* Don't go silent for long periods if the clock goes backwards. */
@@ -1385,6 +1394,9 @@ void clear_cache_and_reload(time_t now)
       if (option_bool(OPT_ETHERS))
 	dhcp_read_ethers();
       reread_dhcp();
+#ifdef HAVE_LINUX_NETWORK
+      set_dhcp_inotify();
+#endif
       dhcp_update_configs(daemon->dhcp_conf);
       lease_update_from_configs(); 
       lease_update_file(now); 

src/dnsmasq.h

@@ -550,13 +550,17 @@ struct resolvc {
 #endif
 };
 
-/* adn-hosts parms from command-line (also dhcp-hostsfile and dhcp-optsfile */
+/* adn-hosts parms from command-line (also dhcp-hostsfile and dhcp-optsfile and dhcp-hostsdir*/
 #define AH_DIR      1
 #define AH_INACTIVE 2
+#define AH_WD_DONE  4
 struct hostsfile {
   struct hostsfile *next;
   int flags;
   char *fname;
+#ifdef HAVE_LINUX_NETWORK
+  int wd; /* inotify watch descriptor */
+#endif
   unsigned int index; /* matches to cache entries for logging */
 };
 
@@ -961,7 +965,7 @@ extern struct daemon {
   int doing_ra, doing_dhcp6;
   struct dhcp_netid_list *dhcp_ignore, *dhcp_ignore_names, *dhcp_gen_names; 
   struct dhcp_netid_list *force_broadcast, *bootp_dynamic;
-  struct hostsfile *dhcp_hosts_file, *dhcp_opts_file;
+  struct hostsfile *dhcp_hosts_file, *dhcp_opts_file, *inotify_hosts;
   int dhcp_max, tftp_max;
   int dhcp_server_port, dhcp_client_port;
   int start_tftp_port, end_tftp_port; 
@@ -1197,7 +1201,7 @@ void reset_option_bool(unsigned int opt);
 struct hostsfile *expand_filelist(struct hostsfile *list);
 char *parse_server(char *arg, union mysockaddr *addr, 
 		   union mysockaddr *source_addr, char *interface, int *flags);
-
+int option_read_hostsfile(char *file);
 /* forward.c */
 void reply_query(int fd, int family, time_t now);
 void receive_query(struct listener *listen, time_t now);
@@ -1486,5 +1490,8 @@ int detect_loop(char *query, int type);
 /* inotify.c */
 #ifdef HAVE_LINUX_NETWORK
 void inotify_dnsmasq_init();
-int inotify_check(void);
+int inotify_check(time_t now);
+#  ifdef HAVE_DHCP
+void set_dhcp_inotify(void);
+#  endif
 #endif

src/inotify.c

@@ -19,6 +19,11 @@
 
 #include <sys/inotify.h>
 
+#ifdef HAVE_DHCP
+static void check_for_dhcp_inotify(struct inotify_event *in, time_t now);
+#endif
+
+
 /* the strategy is to set a inotify on the directories containing
    resolv files, for any files in the directory which are close-write 
    or moved into the directory.
@@ -40,8 +45,6 @@ void inotify_dnsmasq_init()
   struct resolvc *res;
 
   inotify_buffer = safe_malloc(INOTIFY_SZ);
-
-
   daemon->inotifyfd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
   
   if (daemon->inotifyfd == -1)
@@ -66,6 +69,7 @@ void inotify_dnsmasq_init()
 	{
 	  *d = 0; /* make path just directory */
 	  res->wd = inotify_add_watch(daemon->inotifyfd, path, IN_CLOSE_WRITE | IN_MOVED_TO);
+
 	  res->file = d+1; /* pointer to filename */
 	  *d = '/';
 	  
@@ -78,7 +82,7 @@ void inotify_dnsmasq_init()
     }
 }
 
-int inotify_check(void)
+int inotify_check(time_t now)
 {
   int hit = 0;
   
@@ -101,13 +105,116 @@ int inotify_check(void)
 	  for (res = daemon->resolv_files; res; res = res->next)
 	    if (res->wd == in->wd && in->len != 0 && strcmp(res->file, in->name) == 0)
 	      hit = 1;
+
+#ifdef HAVE_DHCP
+	  if (daemon->dhcp || daemon->doing_dhcp6)
+	    check_for_dhcp_inotify(in, now);
+#endif
 	}
     }
-
   return hit;
 }
 
-#endif
+#ifdef HAVE_DHCP 
+/* initialisation for dhcp-hostdir. Set inotify watch for each directory, and read pre-existing files */
+void set_dhcp_inotify(void)
+{
+  struct hostsfile *ah;
+
+  for (ah = daemon->inotify_hosts; ah; ah = ah->next)
+    {
+       DIR *dir_stream = NULL;
+       struct dirent *ent;
+       struct stat buf;
+
+       if (stat(ah->fname, &buf) == -1 || !(S_ISDIR(buf.st_mode)))
+	 {
+	   my_syslog(LOG_ERR, _("bad directory in dhcp-hostsdir %s"), ah->fname);
+	   continue;
+	 }
+
+       if (!(ah->flags & AH_WD_DONE))
+	 {
+	   ah->wd = inotify_add_watch(daemon->inotifyfd, ah->fname, IN_CLOSE_WRITE | IN_MOVED_TO);
+	   ah->flags |= AH_WD_DONE;
+	 }
+       /* Read contents of dir _after_ calling add_watch, in the ho[e of avoiding
+	  a race which misses files being added as we start */
+       if (ah->wd == -1 || !(dir_stream = opendir(ah->fname)))
+	 {
+	   my_syslog(LOG_ERR, _("failed to create inotify for %s"), ah->fname);
+	   continue;
+	 }
+
+       while ((ent = readdir(dir_stream)))
+	 {
+	   size_t lendir = strlen(ah->fname);
+	   size_t lenfile = strlen(ent->d_name);
+	   char *path;
+	   
+	   /* ignore emacs backups and dotfiles */
+	   if (lenfile == 0 || 
+	       ent->d_name[lenfile - 1] == '~' ||
+	       (ent->d_name[0] == '#' && ent->d_name[lenfile - 1] == '#') ||
+	       ent->d_name[0] == '.')
+	     continue;
+	   
+	   if ((path = whine_malloc(lendir + lenfile + 2)))
+	     {
+	       strcpy(path, ah->fname);
+	       strcat(path, "/");
+	       strcat(path, ent->d_name);
+	       
+	       /* ignore non-regular files */
+	       if (stat(path, &buf) != -1 && S_ISREG(buf.st_mode))
+		 option_read_hostsfile(path);
+	       
+	       free(path);
+	     }
+	 }
+    }
+}
+
+static void check_for_dhcp_inotify(struct inotify_event *in, time_t now)
+{
+  struct hostsfile *ah;
+
+  /* ignore emacs backups and dotfiles */
+  if (in->len == 0 || 
+      in->name[in->len - 1] == '~' ||
+      (in->name[0] == '#' && in->name[in->len - 1] == '#') ||
+      in->name[0] == '.')
+    return;
+
+  for (ah = daemon->inotify_hosts; ah; ah = ah->next)
+    if (ah->wd == in->wd)
+      {
+	size_t lendir = strlen(ah->fname);
+	char *path;
+	   
+	if ((path = whine_malloc(lendir + in->len + 2)))
+	  {
+	    strcpy(path, ah->fname);
+	    strcat(path, "/");
+	    strcat(path, in->name);
+	    
+	    if (option_read_hostsfile(path))
+	      {
+		/* Propogate the consequences of loading a new dhcp-host */
+		dhcp_update_configs(daemon->dhcp_conf);
+		lease_update_from_configs(); 
+		lease_update_file(now); 
+		lease_update_dns(1);
+	      }
+	    
+	    free(path);
+	  }
+	
+	return;
+      }
+}
 
+#endif /* DHCP */
 
+#endif  /* LINUX_NETWORK */
   

src/option.c

@@ -149,7 +149,7 @@ struct myoption {
 #define LOPT_LOOP_DETECT   337
 #define LOPT_IGNORE_ADDR   338
 #define LOPT_MINCTTL       339
-
+#define LOPT_DHCP_INOTIFY  340
 
 #ifdef HAVE_GETOPT_LONG
 static const struct option opts[] =  
@@ -248,6 +248,7 @@ static const struct myoption opts[] =
     { "interface-name", 1, 0, LOPT_INTNAME },
     { "dhcp-hostsfile", 1, 0, LOPT_DHCP_HOST },
     { "dhcp-optsfile", 1, 0, LOPT_DHCP_OPTS },
+    { "dhcp-hostsdir", 1, 0, LOPT_DHCP_INOTIFY },
     { "dhcp-no-override", 0, 0, LOPT_OVERRIDE },
     { "tftp-port-range", 1, 0, LOPT_TFTPPORTS },
     { "stop-dns-rebind", 0, 0, LOPT_REBIND },
@@ -336,6 +337,7 @@ static struct {
   { 'G', ARG_DUP, "<hostspec>", gettext_noop("Set address or hostname for a specified machine."), NULL },
   { LOPT_DHCP_HOST, ARG_DUP, "<path>", gettext_noop("Read DHCP host specs from file."), NULL },
   { LOPT_DHCP_OPTS, ARG_DUP, "<path>", gettext_noop("Read DHCP option specs from file."), NULL },
+  { LOPT_DHCP_INOTIFY, ARG_DUP, "<path>", gettext_noop("Read DHCP host specs from a directory."), NULL }, 
   { LOPT_TAG_IF, ARG_DUP, "tag-expression", gettext_noop("Evaluate conditional tag expression."), NULL },
   { 'h', OPT_NO_HOSTS, NULL, gettext_noop("Do NOT load %s file."), HOSTSFILE },
   { 'H', ARG_DUP, "<path>", gettext_noop("Specify a hosts file to be read in addition to %s."), HOSTSFILE },
@@ -1710,8 +1712,9 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
       break;
 #endif /* HAVE_DHCP */
 
-    case LOPT_DHCP_HOST: /* --dhcp-hostfile */
+    case LOPT_DHCP_HOST: /* --dhcp-hostsfile */
     case LOPT_DHCP_OPTS: /* --dhcp-optsfile */
+    case LOPT_DHCP_INOTIFY: /* dhcp-hostsdir */
     case 'H': /* --addn-hosts */
       {
 	struct hostsfile *new = opt_malloc(sizeof(struct hostsfile));
@@ -1734,6 +1737,12 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 	    new->next = daemon->dhcp_opts_file;
 	    daemon->dhcp_opts_file = new;
 	  } 	  
+	else if (option == LOPT_DHCP_INOTIFY)
+	  {
+	    new->next = daemon->inotify_hosts;
+	    daemon->inotify_hosts = new;
+	  }
+	
 	break;
       }
       
@@ -4042,6 +4051,13 @@ static void read_file(char *file, FILE *f, int hard_opt)
   fclose(f);
 }
 
+#ifdef HAVE_DHCP
+int option_read_hostsfile(char *file)
+{
+  return one_file(file, LOPT_BANK);
+}
+#endif
+
 static int one_file(char *file, int hard_opt)
 {
   FILE *f;