joyent/node-cueball#139 want method to retrieve bootstrap resolvers by domain name

docs/api.adoc

@@ -562,7 +562,17 @@ var resolver = mod_cueball.resolverForIpOrDomain({
 In these examples, the `input` string is assumed to come from a user
 cueball does the expected thing when given an IP address or DNS name.
 
+### `DNSResolver.getBootstrapResolver([host])`
 
+Returns the `DNSResolver` created for the input host when
+`resolverForIpOrDomain` is used to create a bootstrap resolver, i.e. a
+resolver for the DNS service itself. If no resolver has yet been created,
+returns `undefined`.
+
+Parameters
+
+- `host` -- String, hostname of the host for which the resolver is being
+requested.
 
 ## Connection interface
 

lib/resolver.js

@@ -400,6 +400,11 @@ CueBallDNSResolver.bootstrapResolvers = {};
 
 CueBallDNSResolver.globalNSClients = {};
 
+CueBallDNSResolver.getBootstrapResolver = function (host) {
+	mod_assert.string(host, 'hostname');
+	return (CueBallDNSResolver.bootstrapResolvers[host]);
+};
+
 CueBallDNSResolver.prototype.start = function () {
 	this.emit('startAsserted');
 };