Implement dns-delete (from Brian Murrell)

common/conflex.c

@@ -22,7 +22,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: conflex.c,v 1.57 1999/10/05 19:43:41 mellon Exp $ Copyright (c) 1995, 1996, 1997, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: conflex.c,v 1.58 1999/10/06 00:59:59 mellon Exp $ Copyright (c) 1995, 1996, 1997, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -463,6 +463,8 @@ static enum dhcp_token intern (atom, dfv)
 			return DDNS_REV_NAME;
 		if (!strcasecmp (atom + 1, "ns-update"))
 			return DNS_UPDATE;
+		if (!strcasecmp (atom + 1, "ns-delete"))
+			return DNS_DELETE;
 		if (!strcasecmp (atom + 1, "omain"))
 			return DOMAIN;
 		if (!strcasecmp (atom + 1, "eny"))

common/nsupdate.c

@@ -25,7 +25,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: nsupdate.c,v 1.9 1999/10/04 23:14:58 mellon Exp $ Copyright (c) 1999 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: nsupdate.c,v 1.10 1999/10/06 00:59:59 mellon Exp $ Copyright (c) 1999 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -580,6 +580,93 @@ int updatePTR (lhs, rhs, ttl, lease)
 
 	return 1;
 }
+/* public function to delete an A record */
+int deleteA (lhs, rhs, lease)
+	const struct data_string *lhs;
+	const struct data_string *rhs;
+	struct lease *lease;
+{
+
+	static char hostname[MAXDNAME];
+	static char ipaddr[MAXDNAME];
+	int y;
+
+	hostname[0] = '\0';
+	strncat(hostname, (const char *)lhs -> data, lhs -> len);
+	hostname[lhs -> len] = '\0';
+	
+	ipaddr[0] = '\0';
+	strncat(ipaddr, (const char *)rhs -> data, rhs -> len);
+	ipaddr[rhs -> len] = '\0';
+
+#if 0	/* Wrong!  This causes zone churn on every DHCPREQUEST!
+	   Besides, it is perfectly legal for a DHCP client to have more
+	   than one lease, if (say) it was being served by two+ DHCP servers
+	   serving the same subnet with different (i.e. disjoint) pools.
+	   The right thing to do is have the A records cleaned by either a
+	   DHCPRELEASE or the lease expiry.  */
+    
+	/* delete all existing A records for this host */
+	nsupdateA (hostname, NULL, 0, DELETE);
+#endif
+
+	y=nsupdateA (hostname, ipaddr, 0, DELETE);
+	if (y < 1)
+		return 0;
+
+#if 0 /* do we really need to do this? */
+	/* clear the forward DNS name pointer */
+	if (lease -> ddns_fwd_name)
+		dfree (lease -> ddns_fwd_name, "nsupdate");
+	lease -> ddns_fwd_name = 0;
+#endif
+
+	return 1;
+}
+
+/* public function to delete a PTR record */
+int deletePTR (lhs, rhs, lease)
+	const struct data_string *lhs;
+	const struct data_string *rhs;
+	struct lease *lease;
+{
+
+	static char hostname[MAXDNAME];
+	static char revname[MAXDNAME];
+	int y;
+
+	revname[0] = '\0';
+	strncat(revname, (const char *)lhs -> data, lhs -> len);
+	revname[lhs -> len] = '\0';
+
+	hostname[0] = '\0';
+	strncat(hostname, (const char *)rhs -> data, rhs -> len);
+	hostname[rhs -> len] = '\0';
+
+#if 0	/* Wrong!  This causes zone churn on every DHCPREQUEST!
+	   Besides, it is perfectly legal for a DHCP client to have more
+	   than one lease, if (say) it was being served by two+ DHCP servers
+	   serving the same subnet with different (i.e. disjoint) pools.
+	   The right thing to do is have the PTR records cleaned by either a
+	   DHCPRELEASE or the lease expiry.  */
+ 	
+	/* delete all existing PTR records */
+	nsupdatePTR (revname, NULL, 0, DELETE);
+#endif
+
+	y=nsupdatePTR (revname, hostname, 0, DELETE);
+	if (y < 1)
+		return 0;
+
+#if 0 /* do we really need to do this? */
+	/* clear the reverse DNS name pointer */
+	if (lease -> ddns_rev_name)
+		dfree (lease -> ddns_rev_name, "nsupdate");
+	lease -> ddns_rev_name = 0;
+#endif
+
+	return 1;
+}
 #endif /* defined (NSUPDATE) */
 
 /* vim: set tabstop=8: */

common/parse.c

@@ -22,7 +22,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: parse.c,v 1.42 1999/10/05 19:43:40 mellon Exp $ Copyright (c) 1995, 1996, 1997, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: parse.c,v 1.43 1999/10/06 01:00:00 mellon Exp $ Copyright (c) 1995, 1996, 1997, 1998, 1999 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -1989,6 +1989,52 @@ int parse_non_binary (expr, cfile, lose, context)
 			goto norparen;
 		break;
 
+	      case DNS_DELETE:
+#if !defined (NSUPDATE)
+		parse_warn (cfile,
+			    "Please rebuild dhcpd with --with-nsupdate.");
+#endif
+		token = next_token (&val, cfile);
+		if (!expression_allocate (expr,
+					  "parse_expression: DNS_DELETE"))
+			log_fatal ("can't allocate expression");
+		(*expr) -> op = expr_dns_delete;
+
+		token = next_token (&val, cfile);
+		if (token != LPAREN)
+			goto nolparen;
+
+		if (!(parse_data_expression
+		      (&(*expr) -> data.dns_update.type, cfile, lose))) {
+			expression_dereference (expr,
+						"parse_expression: noRRtype");
+			parse_warn (cfile, "expecting DNS RR type.");
+			skip_to_semi (cfile);
+			*lose = 1;
+			return 0;
+		}
+
+		token = next_token (&val, cfile);
+		if (token != COMMA)
+			goto nocomma;
+
+		if (!(parse_data_expression
+		      (&(*expr) -> data.dns_update.expr1, cfile, lose)))
+			goto nodata;
+
+		token = next_token (&val, cfile);
+		if (token != COMMA)
+			goto nocomma;
+
+		if (!(parse_data_expression
+		      (&(*expr) -> data.dns_update.expr2, cfile, lose)))
+			goto nodata;
+
+		token = next_token (&val, cfile);
+		if (token != RPAREN)
+			goto norparen;
+		break;
+
 	      case OPTION:
 	      case CONFIG_OPTION:
 		if (!expression_allocate (expr, "parse_expression: OPTION"))

includes/dhctoken.h

@@ -198,6 +198,7 @@ enum dhcp_token {
 	INFINITE = 416,
 	DELETED = 417,
 	UPDATED_DNS_RR = 418,
+	DNS_DELETE = 419,
 };
 
 #define is_identifier(x)	((x) >= FIRST_TOKEN &&	\

includes/tree.h

@@ -93,6 +93,7 @@ enum expr_op {
  	expr_dns_update,
 	expr_static,
 	expr_updated_dns_rr,
+ 	expr_dns_delete,
 };
 
 struct expression {