Enhance --synth-domain to allow names with sequential integers.

CHANGELOG

@@ -50,6 +50,16 @@ version 2.79
 	from files in -dhcp-optsdir directories. Thanks to
 	Lindgren Fredrik for the bug report.
 
+	Add to --synth-domain the ability to create names using
+	sequential numbers, as well as encodings of IP addresses.
+	For instance,
+	--synth-domain=thekelleys.org.uk,192.168.0.50,192.168.0.70,internal-*
+	creates 21 domain names of the form
+	internal-4.thekelleys.org.uk over the address range given, with
+	internal-0.thekelleys.org.uk being 192.168.0.50 and
+	internal-20.thekelleys.org.uk being 192.168.0.70
+	Thanks to Andy Hawkins for the suggestion.
+
 
 version 2.78
         Fix logic of appending ".<layer>" to PXE basename. Thanks to Chris

man/dnsmasq.8

@@ -626,13 +626,16 @@ address by repeating the flag; in that case the first instance is used
 for the reverse address-to-name mapping. Note that a name used in 
 --interface-name may not appear in /etc/hosts.
 .TP
-.B --synth-domain=<domain>,<address range>[,<prefix>]
+.B --synth-domain=<domain>,<address range>[,<prefix>[*]]
 Create artificial A/AAAA and PTR records for an address range. The
-records use the address, with periods (or colons for IPv6) replaced
-with dashes.
+records either seqential numbers or the address, with periods (or colons for IPv6) replaced with dashes.
 
-An example should make this clearer.
-.B --synth-domain=thekelleys.org.uk,192.168.0.0/24,internal-
+An examples should make this clearer. First sequential numbers.
+.B --synth-domain=thekelleys.org.uk,192.168.0.50,192.168.0.70,internal-*
+results in the name internal-0.thekelleys.org.uk. returning 192.168.0.50, internal-1.thekelleys.org.uk returning 192.168.0.51 and so on. (note the *) The same principle applies to IPv6 addresses (where the numbers may be very large). Reverse lookups from address to name behave as expected.
+
+Second, 
+.B --synth-domain=thekelleys.org.uk,192.168.0.0/24,internal- (no *)
 will result in a query for internal-192-168-0-56.thekelleys.org.uk returning
 192.168.0.56 and a reverse query vice versa. The same applies to IPv6,
 but IPv6 addresses may start with '::'
@@ -642,7 +645,7 @@ configured a zero is added in front of the label. ::1 becomes 0--1.
 V4 mapped IPv6 addresses, which have a representation like ::ffff:1.2.3.4 are handled specially, and become like 0--ffff-1-2-3-4
 
 The address range can be of the form
-<ip address>,<ip address> or <ip address>/<netmask>
+<ip address>,<ip address> or <ip address>/<netmask> in both forms of the option.
 .TP
 .B --add-mac[=base64|text]
 Add the MAC address of the requestor to DNS queries which are

src/dnsmasq.h

@@ -839,7 +839,7 @@ struct cond_domain {
 #ifdef HAVE_IPV6
   struct in6_addr start6, end6;
 #endif
-  int is6;
+  int is6, indexed;
   struct cond_domain *next;
 }; 
 

src/domain.c

@@ -56,6 +56,53 @@ int is_name_synthetic(int flags, char *name, struct all_addr *addr)
       if (pref && *pref != 0)
 	continue; /* prefix match fail */
 
+      if (c->indexed)
+	{
+	  for (p = tail; *p; p++)
+	    {
+	      char c = *p;
+	      
+	      if (c < '0' || c > '9')
+		break;
+	    }
+	  
+	  if (*p != '.')
+	    continue;
+	  
+	  *p = 0;
+	  
+	  if (hostname_isequal(c->domain, p+1))
+	    {
+	      if (prot == AF_INET)
+		{
+		  unsigned int index = atoi(tail);
+
+		   if (!c->is6 &&
+		      index <= ntohl(c->end.s_addr) - ntohl(c->start.s_addr))
+		    {
+		      addr->addr.addr4.s_addr = htonl(ntohl(c->start.s_addr) + index);
+		      found = 1;
+		    }
+		}
+#ifdef HAVE_IPV6 
+	      else
+		{
+		  u64 index = atoll(tail);
+		  
+		  if (c->is6 &&
+		      index <= addr6part(&c->end6) - addr6part(&c->start6))
+		    {
+		      u64 start = addr6part(&c->start6);
+		      addr->addr.addr6 = c->start6;
+		      setaddr6part(&addr->addr.addr6, start + index);
+		      found = 1;
+		    }
+		}
+#endif
+	    }
+	}
+      else
+	{
 	  /* NB, must not alter name if we return zero */
 	  for (p = tail; *p; p++)
 	    {
@@ -77,7 +124,7 @@ int is_name_synthetic(int flags, char *name, struct all_addr *addr)
 	  
 	  *p = 0;	
 	  
- #ifdef HAVE_IPV6
+#ifdef HAVE_IPV6
 	  if (prot == AF_INET6 && strstr(tail, "--ffff-") == tail)
 	    {
 	      /* special hack for v4-mapped. */
@@ -125,6 +172,8 @@ int is_name_synthetic(int flags, char *name, struct all_addr *addr)
 #endif
 	    }
 
+	}
+
       /* restore name */
       for (p = tail; *p; p++)
 	if (*p == '.' || *p == ':')
@@ -132,6 +181,7 @@ int is_name_synthetic(int flags, char *name, struct all_addr *addr)
       
       *p = '.';
       
+      
       if (found)
 	return 1;
     }
@@ -149,6 +199,13 @@ int is_rev_synth(int flag, struct all_addr *addr, char *name)
        char *p;
        
        *name = 0;
+       if (c->indexed)
+	 {
+	   unsigned int index = ntohl(addr->addr.addr4.s_addr) - ntohl(c->start.s_addr);
+	   snprintf(name, MAXDNAME, "%s%u", c->prefix ? c->prefix : "", index);
+	 }
+       else
+	 {
 	   if (c->prefix)
 	     strncpy(name, c->prefix, MAXDNAME - ADDRSTRLEN);
        
@@ -156,6 +213,7 @@ int is_rev_synth(int flag, struct all_addr *addr, char *name)
 	   for (p = name; *p; p++)
 	     if (*p == '.')
 	       *p = '-';
+	 }
        
        strncat(name, ".", MAXDNAME);
        strncat(name, c->domain, MAXDNAME);
@@ -169,6 +227,13 @@ int is_rev_synth(int flag, struct all_addr *addr, char *name)
        char *p;
        
        *name = 0;
+       if (c->indexed)
+	 {
+	   u64 index = addr6part(&addr->addr.addr6) - addr6part(&c->start6);
+	   snprintf(name, MAXDNAME, "%s%llu", c->prefix ? c->prefix : "", index);
+	 }
+       else
+	 {
 	   if (c->prefix)
 	     strncpy(name, c->prefix, MAXDNAME - ADDRSTRLEN);
        
@@ -187,6 +252,8 @@ int is_rev_synth(int flag, struct all_addr *addr, char *name)
 	     if (*p == ':' || *p == '.')
 	       *p = '-';
 	   
+	 }
+
        strncat(name, ".", MAXDNAME);
        strncat(name, c->domain, MAXDNAME);
        

src/option.c

@@ -2071,6 +2071,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 		  char *netpart;
 		  
 		  new->prefix = NULL;
+		  new->indexed = 0;
 		  
 		  unhide_metas(comma);
 		  if ((netpart = split_chr(comma, '/')))
@@ -2208,8 +2209,14 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 		    }
 		  else
 		    {
+		      char *star;
 		      new->next = daemon->synth_domains;
 		      daemon->synth_domains = new;
+		      if ((star = strrchr(new->prefix, '*')) && *(star+1) == 0)
+			{
+			  *star = 0;
+			  new->indexed = 1;
+			}
 		    }
 		}
 	      else if (option == 's')