Index: hosts_access.5
===================================================================
RCS file: /cvs/misc/tcp_wrappers/hosts_access.5,v
retrieving revision 1.1.1.1
diff -c -r1.1.1.1 hosts_access.5
*** hosts_access.5	1995/08/11 17:33:12	1.1.1.1
--- hosts_access.5	1998/10/08 01:11:40
***************
*** 112,117 ****
--- 112,122 ----
  built with -DPARANOID (default mode), it drops requests from such
  clients even before looking at the access control tables.  Build
  without -DPARANOID when you want more control over such requests.
+ .IP "{RBL}.\fIdomain\fR"
+ Matches any host whose reversed address appears in the DNS under
+ \fIdomain\fR.  Example domains used for blocking unsolicited
+ commercial e-mail (aka `spam\') are `.rbl.maps.vix.com\',
+ `.dul.maps.vix.com\', and `.relays.orbs.org\'.
  .ne 6
  .SH OPERATORS
  .IP EXCEPT
Index: hosts_access.c
===================================================================
RCS file: /cvs/misc/tcp_wrappers/hosts_access.c,v
retrieving revision 1.1.1.3
diff -c -r1.1.1.3 hosts_access.c
*** hosts_access.c	1997/05/24 23:07:38	1.1.1.3
--- hosts_access.c	1999/03/08 04:12:09
***************
*** 80,85 ****
--- 80,86 ----
  static int server_match();
  static int client_match();
  static int host_match();
+ static int rbl_match();
  static int string_match();
  static int masked_match();
  
***************
*** 273,284 ****
--- 274,325 ----
      } else if (STR_EQ(tok, "LOCAL")) {		/* local: no dots in name */
  	char   *name = eval_hostname(host);
  	return (strchr(name, '.') == 0 && HOSTNAME_KNOWN(name));
+     } else if (strncmp(tok, "{RBL}.", 6) == 0) { /* RBL lookup in domain */
+ 	return rbl_match(tok+6, eval_hostaddr(host));
      } else if ((mask = split_at(tok, '/')) != 0) {	/* net/mask */
  	return (masked_match(tok, mask, eval_hostaddr(host)));
      } else {					/* anything else */
  	return (string_match(tok, eval_hostaddr(host))
  	    || (NOT_INADDR(tok) && string_match(tok, eval_hostname(host))));
      }
+ }
+ 
+ /* rbl_match() - match host by looking up in RBL domain */
+ 
+ static int rbl_match(rbl_domain, rbl_hostaddr)
+ char   *rbl_domain;				/* RBL domain */
+ char   *rbl_hostaddr;				/* hostaddr */
+ {
+     char *rbl_name;
+     unsigned long host_address;
+     char *p;
+     int ret = NO;
+     extern char *malloc();
+  
+     if ((host_address = dot_quad_addr(rbl_hostaddr)) == INADDR_NONE) {
+ 	tcpd_warn("unable to convert %s to address", rbl_hostaddr);
+ 	return (NO);
+     }
+     /*  construct the rbl name to look up */
+     if ((rbl_name = malloc(sizeof("255.255.255.255.") + strlen(rbl_domain) + 1)) == NULL) {
+ 	tcpd_jump("not enough memory to build RBL name for %s in %s", rbl_hostaddr, rbl_domain);
+ 	/* NOTREACHED */
+     }
+     p = (char *) (void *) &host_address;
+ 
+ #define UC(byte)	(((int)(byte)) & 0xff)
+ 
+     sprintf(rbl_name, "%d.%d.%d.%d.%s", UC(p[3]), UC(p[2]), UC(p[1]), UC(p[0]), rbl_domain);
+ #undef UC
+     /* look it up */
+     if (gethostbyname(rbl_name) != NULL) {
+ 	/* successful lookup - they're on the RBL list */
+ 	/* XXX convention is the A RR returned should be 127.0.0.2 */
+ 	ret = YES;
+     }
+     free(rbl_name);
+ 
+     return ret;
  }
  
  /* string_match - match string against pattern */

.