Allow option prefix in --synth-domain.

man/dnsmasq.8

@@ -519,17 +519,18 @@ the name. More than one name may be associated with an interface
 address by repeating the flag; in that case the first instance is used
 for the reverse address-to-name mapping.
 .TP
-.B --synth-domain=<domain>,<address range>
+.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.
 
 An example should make this clearer.
-.B --synth-domain=thekelleys.org.uk,192.168.0.0/24 
-will result in a query for 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 '::'
-but DNS labels may not start with '-' so in this case a zero is added
-in front of the label. ::1 becomes 0--1.
+.B --synth-domain=thekelleys.org.uk,192.168.0.0/24,internal-
+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 '::'
+but DNS labels may not start with '-' so in this case if no prefix is
+configured a zero is added in front of the label. ::1 becomes 0--1.
 
 The address range can be of the form
 <ip address>,<ip address> or <ip address>/<netmask>

src/dnsmasq.h

@@ -673,7 +673,7 @@ struct dhcp_bridge {
 };
 
 struct cond_domain {
-  char *domain;
+  char *domain, *prefix;
   struct in_addr start, end;
 #ifdef HAVE_IPV6
   struct in6_addr start6, end6;

src/domain.c

@@ -34,48 +34,69 @@ int is_name_synthetic(int flags, char *name, struct all_addr *addr)
     prot = AF_INET6;
 #endif
 
-  /* NB, must not alter name if we return zero */
-  for (p = name; *p; p++)
+  for (c = daemon->synth_domains; c; c = c->next)
     {
-      char c = *p;
+      int found = 0;
+      char *tail, *pref;
       
-      if ((c >='0' && c <= '9') || c == '-')
-	continue;
+      for (tail = name, pref = c->prefix; *tail != 0 && pref && *pref != 0; tail++, pref++)
+	{
+	  unsigned int c1 = (unsigned char) *pref;
+	  unsigned int c2 = (unsigned char) *tail;
+	  
+	  if (c1 >= 'A' && c1 <= 'Z')
+	    c1 += 'a' - 'A';
+	  if (c2 >= 'A' && c2 <= 'Z')
+	    c2 += 'a' - 'A';
+	  
+	  if (c1 != c2)
+	    break;
+	}
+      
+      if (pref && *pref != 0)
+	continue; /* prefix match fail */
       
+      /* NB, must not alter name if we return zero */
+      for (p = tail; *p; p++)
+	{
+	  char c = *p;
+	  
+	  if ((c >='0' && c <= '9') || c == '-')
+	    continue;
+	  
 #ifdef HAVE_IPV6
-      if (prot == AF_INET6 && ((c >='A' && c <= 'F') || (c >='a' && c <= 'f'))) 
-	continue;
+	  if (prot == AF_INET6 && ((c >='A' && c <= 'F') || (c >='a' && c <= 'f'))) 
+	    continue;
 #endif
+	  
+	  break;
+	}
       
-      break;
-    }
-  
-  if (*p != '.')
-    return 0;
-  
-  *p = 0;	
-
-  for (p = name; *p; p++)
-    if (*p == '-')
-      {
-	if (prot == AF_INET)
-	  *p = '.';
+      if (*p != '.')
+	continue;
+      
+      *p = 0;	
+      
+      /* swap . or : for - */
+      for (p = tail; *p; p++)
+	if (*p == '-')
+	  {
+	    if (prot == AF_INET)
+	      *p = '.';
 #ifdef HAVE_IPV6
-	else
-	  *p = ':';
+	    else
+	      *p = ':';
 #endif
-      }
- 
-  if (inet_pton(prot, name, addr))
-    for (c = daemon->synth_domains; c; c = c->next)
-      if (hostname_isequal(c->domain, p+1))
+	  }
+      
+      if (hostname_isequal(c->domain, p+1) && inet_pton(prot, tail, addr))
 	{
 	  if (prot == AF_INET)
 	    {
 	      if (!c->is6 &&
 		  ntohl(addr->addr.addr4.s_addr) >= ntohl(c->start.s_addr) &&
 		  ntohl(addr->addr.addr4.s_addr) <= ntohl(c->end.s_addr))
-		break;
+		found = 1;
 	    }
 #ifdef HAVE_IPV6
 	  else
@@ -86,20 +107,23 @@ int is_name_synthetic(int flags, char *name, struct all_addr *addr)
 		  is_same_net6(&addr->addr.addr6, &c->start6, 64) &&
 		  addrpart >= addr6part(&c->start6) &&
 		  addrpart <= addr6part(&c->end6))
-		break;
+		found = 1;
 	    }
 #endif
 	}
+      
+      /* restore name */
+      for (p = tail; *p; p++)
+	if (*p == '.' || *p == ':')
+	  *p = '-';
+      
+      *p = '.';
+
+      if (found)
+	return 1;
+    }
   
-  /* restore name */
-  for (p = name; *p; p++)
-    if (*p == '.' || *p == ':')
-      *p = '-';
-  
-  *p = '.';
-  
-  return (c != NULL);
-  
+  return 0;
 }
 
 
@@ -111,7 +135,11 @@ int is_rev_synth(int flag, struct all_addr *addr, char *name)
      {
        char *p;
        
-       inet_ntop(AF_INET, &addr->addr.addr4, name, ADDRSTRLEN);
+       *name = 0;
+       if (c->prefix)
+	 strncpy(name, c->prefix, MAXDNAME - ADDRSTRLEN);
+       
+       inet_ntop(AF_INET, &addr->addr.addr4, name + strlen(name), ADDRSTRLEN);
        for (p = name; *p; p++)
 	 if (*p == '.')
 	   *p = '-';
@@ -127,11 +155,15 @@ int is_rev_synth(int flag, struct all_addr *addr, char *name)
      {
        char *p;
        
-       inet_ntop(AF_INET6, &addr->addr.addr6, name, ADDRSTRLEN);
+       *name = 0;
+       if (c->prefix)
+	 strncpy(name, c->prefix, MAXDNAME - ADDRSTRLEN);
+       
+       inet_ntop(AF_INET6, &addr->addr.addr6, name + strlen(name), ADDRSTRLEN);
 
        /* IPv6 presentation address can start with ":", but valid domain names
 	  cannot start with "-" so prepend a zero in that case. */
-       if (*name == ':')
+       if (!c->prefix && *name == ':')
 	 {
 	   *name = '0';
 	   inet_ntop(AF_INET6, &addr->addr.addr6, name+1, ADDRSTRLEN);

src/option.c

@@ -408,7 +408,7 @@ static struct {
   { LOPT_AUTHSFS, ARG_DUP, "<NS>[,<NS>...]", gettext_noop("Secondary authoritative nameservers for forward domains"), NULL },
   { LOPT_AUTHPEER, ARG_DUP, "<ipaddr>[,<ipaddr>...]", gettext_noop("Peers which are allowed to do zone transfer"), NULL },
   { LOPT_IPSET, ARG_DUP, "/<domain>/<ipset>[,<ipset>...]", gettext_noop("Specify ipsets to which matching domains should be added"), NULL },
-  { LOPT_SYNTH, ARG_DUP, "<domain>,<range>", gettext_noop("Specify a domain and address range for sythesised names"), NULL },
+  { LOPT_SYNTH, ARG_DUP, "<domain>,<range>,[<prefix>]", gettext_noop("Specify a domain and address range for sythesised names"), NULL },
 #ifdef OPTION6_PREFIX_CLASS 
   { LOPT_PREF_CLSS, ARG_DUP, "set:tag,<class>", gettext_noop("Specify DHCPv6 prefix class"), NULL },
 #endif
@@ -1707,6 +1707,8 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 		  struct cond_domain *new = opt_malloc(sizeof(struct cond_domain));
 		  char *netpart;
 		  
+		  new->prefix = NULL;
+
 		  unhide_metas(comma);
 		  if ((netpart = split_chr(comma, '/')))
 		    {
@@ -1723,26 +1725,26 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 			  new->end.s_addr = new->start.s_addr | htonl(mask);
 			  if (arg)
 			    {
-			      /* generate the equivalent of
-				 local=/<domain>/
-				 local=/xxx.yyy.zzz.in-addr.arpa/ */
-
-			      if (strcmp(arg, "local") != 0 ||
-				  option != 's' ||
-				  (msize != 8 && msize != 16 && msize != 24))
+			      if (option != 's')
+				new->prefix = canonicalise_opt(arg);
+			      else if (strcmp(arg, "local") != 0 ||
+				       (msize != 8 && msize != 16 && msize != 24))
 				ret_err(gen_err);
 			      else
 				{
+				  /* generate the equivalent of
+				     local=/<domain>/
+				     local=/xxx.yyy.zzz.in-addr.arpa/ */
 				  struct server *serv = opt_malloc(sizeof(struct server));
 				  in_addr_t a = ntohl(new->start.s_addr) >> 8;
 				  char *p;
-
+				  
 				  memset(serv, 0, sizeof(struct server));
 				  serv->domain = d;
 				  serv->flags = SERV_HAS_DOMAIN | SERV_NO_ADDR;
 				  serv->next = daemon->servers;
 				  daemon->servers = serv;
-
+				  
 				  serv = opt_malloc(sizeof(struct server));
 				  memset(serv, 0, sizeof(struct server));
 				  p = serv->domain = opt_malloc(25); /* strlen("xxx.yyy.zzz.in-addr.arpa")+1 */
@@ -1754,7 +1756,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 				    p += sprintf(p, "%d.", a & 0xff);
 				  a = a >> 8;
 				  p += sprintf(p, "%d.in-addr.arpa", a & 0xff);
-
+				  
 				  serv->flags = SERV_HAS_DOMAIN | SERV_NO_ADDR;
 				  serv->next = daemon->servers;
 				  daemon->servers = serv;
@@ -1767,11 +1769,11 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 			  u64 mask = (1LLU << (128 - msize)) - 1LLU;
 			  u64 addrpart = addr6part(&new->start6);
 			  new->is6 = 1;
-
+			  
 			  /* prefix==64 overflows the mask calculation above */
 			  if (msize == 64)
 			    mask = (u64)-1LL;
-
+			  
 			  new->end6 = new->start6;
 			  setaddr6part(&new->start6, addrpart & ~mask);
 			  setaddr6part(&new->end6, addrpart | mask);
@@ -1780,16 +1782,15 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 			    ret_err(gen_err);
 			  else if (arg)
 			    {
-			      /* generate the equivalent of
-				 local=/<domain>/
-				 local=/xxx.yyy.zzz.ip6.arpa/ */
-
-			      if (strcmp(arg, "local") != 0 || 
-				  option != 's' ||
-				  ((msize & 4) != 0))
+			      if (option != 's')
+				new->prefix = canonicalise_opt(arg);
+			      else if (strcmp(arg, "local") != 0 || ((msize & 4) != 0))
 				ret_err(gen_err);
 			      else 
 				{
+				  /* generate the equivalent of
+				     local=/<domain>/
+				     local=/xxx.yyy.zzz.ip6.arpa/ */
 				  struct server *serv = opt_malloc(sizeof(struct server));
 				  char *p;