RA configuration tweaks and documentation improvements.

dnsmasq.conf.example

@@ -161,9 +161,13 @@
 # and defaults to 64 if missing/
 #dhcp-range=1234::2, 1234::500, 64, 12h
 
-# Not Router Advertisements, BUT NOT DHCP for this subnet.
+# Do Router Advertisements, BUT NOT DHCP for this subnet.
 #dhcp-range=1234::, ra-only 
 
+# Do Router Advertisements, BUT NOT DHCP for this subnet.
+# Set the lifetime to 46 hours. (Note: minimum lifetime is 2 hours.)
+#dhcp-range=1234::, ra-only, 48h
+
 # Supply parameters for specified hosts using DHCP. There are lots
 # of valid alternatives, so we will give examples of each. Note that
 # IP addresses DO NOT have to be in the range given above, they just
@@ -284,7 +288,11 @@
 #dhcp-option=option:ntp-server,192.168.0.4,10.10.0.5
 
 # Send DHCPv6 option. Note [] around IPv6 addresses.
-dhcp-option=option6:dns-server,[1234::77],[1234::88]
+#dhcp-option=option6:dns-server,[1234::77],[1234::88]
+
+# Send DHCPv6 option for namservers as the machine running 
+# dnsmasq and another.
+#dhcp-option=option6:dns-server,[::],[1234::88]
 
 # Set the NTP time server address to be the same machine as
 # is running dnsmasq

man/dnsmasq.8

@@ -704,7 +704,7 @@ and to set the time-server address to 192.168.0.4, do
 .B --dhcp-option = 42,192.168.0.4 
 or 
 .B --dhcp-option = option:ntp-server, 192.168.0.4
-The special address 0.0.0.0 is taken to mean "the address of the
+The special address 0.0.0.0 (or [::] for DHCPv6) is taken to mean "the address of the
 machine running dnsmasq". Data types allowed are comma separated
 dotted-quad IP addresses, a decimal number, colon-separated hex digits
 and a text string. If the optional tags are given then
@@ -1256,9 +1256,15 @@ existing DHCP configuration to provide most data. When RA is enabled,
 dnsmasq will advertise a prefix for each dhcp-range, with default
 router and recursive DNS server as the relevant link-local address on 
 the machine running dnsmasq. The "managed address" bits are set,
-except for a dhcp-range which is marked as "ra-only". In which case RA
+except for a dhcp-range which is marked as "ra-only", in which case RA
 is provided by no DHCPv6 service and the managed address bits are
-cleared.
+cleared. 
+.B enable-ra
+enables router advertisement for prefixes where dnsmasq is doing
+DHCPv6. It is not needed to "ra-only" prefixes. Creating an "ra-only"
+prefix and not setting 
+.B enable-ra
+sends advertisements only to "ra-only" prefixes. 
 .TP
 .B --enable-tftp[=<interface>]
 Enable the TFTP server function. This is deliberately limited to that

src/radv.c

@@ -275,8 +275,13 @@ static int add_prefixes(struct in6_addr *local,  int prefix,
 		is_same_net6(local, &context->end6, prefix))
 	      {
 		if (!(context->flags & CONTEXT_RA_ONLY))
-		  param->managed = 1;
-	
+		  {
+		    /* don't do RA for non-ra-only unless --enable-ra is set */
+		    if (!option_bool(OPT_RA))
+		      continue;
+		    param->managed = 1;
+		  }
+
 		if (context->flags & CONTEXT_RA_DONE)
 		  continue;