add DNS64 documentation, plus dns64 sample script to the tree

diff --git a/pdns/dns64.lua b/pdns/dns64.lua
new file mode 100644 (file)
index 0000000..62a4864
--- /dev/null
+++ b/pdns/dns64.lua
@@ -0,0 +1,23 @@
+-- this small script implements dns64 without any specials or customization
+-- the pref64 is "fe80::21b::77ff:0:0", and it appears twice, plus once reversed
+
+function nodata ( remoteip, domain, qtype, records )
+       if qtype ~= pdns.AAAA then return -1, {} end  --  only AAAA records
+        setvariable()
+        return "getFakeAAAARecords", domain, "fe80::21b:77ff:0:0"
+end     
+
+function endswith(s, send)
+       return #s >= #send and s:find(send, #s-#send+1, true) and true or false
+end
+
+-- note that the ip6.arpa string ends on a .
+-- it is the reverse of the pref64 address above
+
+function preresolve ( remoteip, domain, qtype )
+       if qtype ==pdns.PTR and endswith(domain, "f.f.7.7.b.1.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.e.f.ip6.arpa.")
+        then
+               return "getFakePTRRecords", domain, "fe80::21b::77ff:0:0"
+       end
+       return -1, {}
+end

diff --git a/pdns/docs/pdns.xml b/pdns/docs/pdns.xml
index ef68518e72c2ef754a1bdf0d3fb2d57d08b9ac5f..592cb6d21a9563a11297291d5a5a45b4e0239fed 100644 (file)
--- a/pdns/docs/pdns.xml
+++ b/pdns/docs/pdns.xml
@@ -9,7 +9,7 @@
       <affiliation>
         <orgname>PowerDNS BV</orgname>
         <address>
-          <email>powerdns.support@netherlabs.nl</email>
+          <email>powerdns.support@powerdns.com</email>
         </address>
       </affiliation>
     </author>
@@ -13934,6 +13934,62 @@ end
        </para>
       </sect2>
     </sect1>
+    <sect1 id="dns64"><title>DNS64 support in the PowerDNS Recursor</title>
+      <para>
+       DNS64 is a technology to allow IPv6-only clients to receive special IPv6 addresses that are proxied to 
+       IPv4 addresses. This proxy service is then called NAT64. 
+      </para>
+      <para>
+       So, as an example, let's say an IPv6 only client would want to connect to www.example.com, it would request the AAAA records
+       for that name. However, if example.com does not actually have an IPv6 address, what we do is 'fake up' an IPv6 address. We do this
+       by retrieving the A records for www.example.com, and translating them to AAAA records.
+      </para>
+      <para>
+       Elsewhere, a NAT64 device listens on these IPv6 addresses, and extracts the IPv4 address from each packet, and proxies it on
+      </para>
+      <para>
+       DNS64 is described in RFC 6147, and is supported by the PowerDNS Recursor since version 3.4.
+      </para>
+      <para>
+       For maximum flexibility, DNS64 support is included in the Lua scripting engine. This allows for example to hand out
+       custom IPv6 gateway ranges depending on the location of the requestor, enabling the use of NAT64 services close to the user.
+      </para>
+      <para>
+       To setup DNS64, create the following Lua script and save it to a file called dns64.lua:
+       <programlisting>
+       function nodata ( remoteip, domain, qtype, records )
+             if qtype ~= pdns.AAAA then return -1, {} end  --  only AAAA records
+             setvariable()
+             return "getFakeAAAARecords", domain, "fe80::21b:77ff:0:0"
+        end     
+       </programlisting>
+       Where fe80::21b::77ff:0:0 is your "Pref64" translation prefix. Next, make sure your script gets loaded
+       by specifying it with "lua-pdns-script=dns64.lua".
+      </para>
+      <para>
+       In addition, since PowerDNS Recursor 3.6, it is also possible to also generate the associated PTR records.
+       This makes sure that reverse lookup if IPv6 addresses generate the right name. The procedure is similar,
+       a request for an IPv6 PTR is converted into one for the corresponding IPv4 address.
+      </para>
+      <para>
+       To hook up the generation of PTR records, include:
+       <programlisting>
+         function endswith(s, send)
+             return #s >= #send and s:find(send, #s-#send+1, true) and true or false
+         end
+
+         function preresolve ( remoteip, domain, qtype )
+            if qtype ==pdns.PTR and endswith(domain, "f.f.7.7.b.1.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.e.f.ip6.arpa.")
+             then
+                print("This is our faked AAAA record in reverse")
+                return "getFakePTRRecords", domain, "fe80::21b::77ff:0:0"
+             end
+            return -1, {}
+         end
+       </programlisting>
+       Where the "ip6.arpa" string is the reversed form of your Pref64 address.
+      </para>
+    </sect1>
     <sect1 id="recursor-design-and-engineering">
       <title>Design and Engineering of the PowerDNS Recursor</title>
       <para>