DDNS feature request with patch

[Ferenc Kiraly]

	Hi!

I have a delegated DNS subdomain according to RFC2317, where the reverse 
lookup zone name looks like "192-255.1.168.192.in-addr.arpa". As far as 
I can see, I cannot use the DHCP server's DDNS feature to update records 
in this kind of zone, because I have no way of specifying the correct 
reverse domain name. The current implementation appends a given string 
(default is ".in-addr.arpa") to the reversed IP address of the client, 
to form something like this: "193.1.168.192.in-addr.arpa".

I need DDNS updates for this kind of domains quite badly, so I added a 
boolean option called "ddns-rev-domainname-replace", which causes only 
the last octet of the IP address of the client to be used instead of the 
entire reversed IP address. So a DDNS update correctly applies for a PTR 
record of the form "193.192-255.1.168.192.in-addr.arpa".

Of course this feature can be expanded to use more (or less) than one 
octet, according to the netmask, but one octet works fine for me for 
now. If this patch sounds reasonable enough for inclusion into the DHCP 
server, I would be willing to spend the effort to make the patch acceptable.


	feri.

The patch follows:
------------------- snip ----------------------------------------------
diff -urN dhcp-3.0.1rc13.orig/includes/dhcpd.h 
dhcp-3.0.1rc13/includes/dhcpd.h
--- dhcp-3.0.1rc13.orig/includes/dhcpd.h	2003-02-10 02:22:46.000000000 +0100
+++ dhcp-3.0.1rc13/includes/dhcpd.h	2004-04-18 13:27:14.000000000 +0200
@@ -421,6 +421,7 @@
  #define SV_LOG_FACILITY			44
  #define SV_DO_FORWARD_UPDATES		45
  #define SV_PING_TIMEOUT         46
+#define SV_DDNS_REV_DOMAIN_NAME_REPLACE	47

  #if !defined (DEFAULT_PING_TIMEOUT)
  # define DEFAULT_PING_TIMEOUT 1
diff -urN dhcp-3.0.1rc13.orig/server/ddns.c dhcp-3.0.1rc13/server/ddns.c
--- dhcp-3.0.1rc13.orig/server/ddns.c	2002-11-17 03:29:30.000000000 +0100
+++ dhcp-3.0.1rc13/server/ddns.c	2004-04-18 13:33:00.000000000 +0200
@@ -471,6 +471,8 @@
  	/*
  	 * Compute the reverse IP name.
  	 */
+	s1 = s2 = 0;
+	
  	oc = lookup_option (&server_universe, state -> options,
  			    SV_DDNS_REV_DOMAIN_NAME);
  	if (oc)
@@ -480,7 +482,39 @@
  					    state -> options,
  					    &lease -> scope, oc, MDL);
  	
-	if (oc && s1) {
+	oc = lookup_option (&server_universe, state -> options,
+			    SV_DDNS_REV_DOMAIN_NAME_REPLACE);
+	if (oc)
+		s2 = evaluate_boolean_option_cache (&ignorep, packet, lease,
+					    (struct client_state *)0,
+					    packet -> options,
+					    state -> options,
+					    &lease -> scope, oc, MDL);
+	
+	if (s1 && s2) {
+                /* Buffer length:
+		 * XXX.<ddns-rev-domain-name>\0
+		 * where XXX is the last octet of the IP */
+                buffer_allocate (&ddns_rev_name.buffer,
+                                 d1.len + 5, MDL);
+                if (ddns_rev_name.buffer) {
+                        ddns_rev_name.data = ddns_rev_name.buffer -> data;
+#ifndef NO_SNPRINTF
+                        snprintf ((char *)ddns_rev_name.buffer -> data, 17,
+	                          "%d.", lease -> ip_addr . iabuf[3]);
+#else
+	                sprintf ((char *)ddns_rev_name.buffer -> data,
+                                 "%d.", lease -> ip_addr . iabuf[3]);
+#endif
+                        ddns_rev_name.len =
+                                strlen ((const char *)ddns_rev_name.data);
+                        data_string_append (&ddns_rev_name, &d1);
+                        ddns_rev_name.buffer -> data 
[ddns_rev_name.len] ='\0';
+                        ddns_rev_name.terminated = 1;
+                }
+
+                data_string_forget (&d1, MDL);
+	} else if (s1) {
  		/* Buffer length:
  		   XXX.XXX.XXX.XXX.<ddns-rev-domain-name>\0 */
  		buffer_allocate (&ddns_rev_name.buffer,
diff -urN dhcp-3.0.1rc13.orig/server/stables.c 
dhcp-3.0.1rc13/server/stables.c
--- dhcp-3.0.1rc13.orig/server/stables.c	2003-02-10 02:22:54.000000000 +0100
+++ dhcp-3.0.1rc13/server/stables.c	2004-04-18 13:28:26.000000000 +0200
@@ -492,7 +492,7 @@
  	{ "log-facility", "Nsyslog-facilities.",	&server_universe, 44 },
  	{ "do-forward-updates", "f",			&server_universe, 45 },
  	{ "ping-timeout", "T",				&server_universe, 46 },
-	{ "unknown-47", "X",				&server_universe, 47 },
+	{ "ddns-rev-domainname-replace", "f",		&server_universe, 47 },
  	{ "unknown-48", "X",				&server_universe, 48 },
  	{ "unknown-49", "X",				&server_universe, 49 },
  	{ "unknown-50", "X",				&server_universe, 50 },