fold sysinfo into network

the backends are network backends

src/network/fixed.js

@@ -0,0 +1,44 @@
+'use strict';
+
+exports = module.exports = {
+    getIPv4,
+    getIPv6,
+    testIPv4Config,
+    testIPv6Config
+};
+
+const assert = require('assert'),
+    BoxError = require('../boxerror.js'),
+    net = require('net');
+
+async function getIPv4(config) {
+    assert.strictEqual(typeof config, 'object');
+
+    return config.ipv4;
+}
+
+async function getIPv6(config) {
+    assert.strictEqual(typeof config, 'object');
+
+    if ('ipv6' in config) return config.ipv6;
+
+    throw new BoxError(BoxError.NETWORK_ERROR, 'No IPv6 configured');
+}
+
+async function testIPv4Config(config) {
+    assert.strictEqual(typeof config, 'object');
+
+    if (typeof config.ipv4 !== 'string') return new BoxError(BoxError.BAD_FIELD, 'ipv4 must be a string');
+    if (!net.isIPv4(config.ipv4)) return new BoxError(BoxError.BAD_FIELD, 'invalid IPv4');
+
+    return null;
+}
+
+async function testIPv6Config(config) {
+    assert.strictEqual(typeof config, 'object');
+
+    if (typeof config.ipv6 !== 'string') return new BoxError(BoxError.BAD_FIELD, 'ipv6 must be a string');
+    if (!net.isIPv6(config.ipv6)) return new BoxError(BoxError.BAD_FIELD, 'invalid IPv6');
+
+    return null;
+}