Fix conversion of IPv4/IPv6 bindata to strings

The documentation mentions taking care of bindata (buffers in node), such as IPv4 and IPV6 addresses, and converting them to easy-to-use javascript strings where possible. This was apparently not happening for at least `just_address_answers`, due to a small bug in the `getdns_dict_to_ip_string()` function. The tests were written to match the buffer output, so this documentation mismatch/bug was not detected.

This fixes getdnsapi#16 and should align the documentation and the code.

Author: joelpurra

README.md

@@ -133,7 +133,7 @@ Bindatas are converted to strings when possible:
 - printable bindata
 - wire format dname
 
-All other bindata objects are converted into Node.js buffers (represented below as <node buffer>)
+All other bindata objects are converted into Node.js buffers (represented below as `<node buffer>`)
 
 Also see the output of the examples:
 

src/GNUtil.cpp

@@ -355,7 +355,7 @@ char* getdns_dict_to_ip_string(getdns_dict* dict) {
     if (r != GETDNS_RETURN_GOOD) {
         return NULL;
     }
-    if (data->size == 5 &&
+    if (data->size == 4 &&
         (strcmp("IPv4", (char*) data->data) == 0 ||
          strcmp("IPv6", (char*) data->data) == 0)) {
         r = getdns_dict_get_bindata(dict, "address_data", &data);

test/test.js

@@ -33,6 +33,7 @@ it:false,
 "use strict";
 
 // Requires.
+const net = require("net");
 const expect = require("expect.js");
 const getdns = require("../");
 const async = require("async");
@@ -83,9 +84,9 @@ describe("getdns test", () => {
                 expect(result).to.be.ok();
                 expect(result.just_address_answers).to.be.an(Array);
                 expect(result.just_address_answers).to.not.be.empty();
-                result.just_address_answers.map((r) => {
-                    expect(r.address_type).to.be.an("string");
-                    expect(r.address_data).to.be.an(Buffer);
+                result.just_address_answers.map((address) => {
+                    expect(address).to.be.an("string");
+                    expect(net.isIP(address)).to.be.ok();
                 });
                 finish(ctx, done);
             });