DNS Library

The DNS builtin library is AdeshLang's production-grade, high-performance, secure DNS resolution and protocol subsystem. Designed cleanly on top of Net, it provides hostname resolution, record querying, service discovery, thread-safe LRU caching, and SSRF security policy sandboxing.

All binary wire encoders and decoders operate under strict safety bounds — enforcing maximum domain label lengths (≤ 63 octets), full domain lengths (≤ 255 octets), and compression pointer loop protection with a maximum recursion depth of 16.

Namespace

Name	What it provides
DNS	The primary DNS namespace: resolve, query, reverseLookup, discover, Resolver, and Policy

Importing the library

import DNS;              // or import "std:DNS" as DNS;

Selective imports work too:

import { resolve, query, reverseLookup, discover } from DNS;

---

High-Level Resolution (DNS.resolve)

Resolves a domain name into an array of IPv4 and IPv6 address strings.

Function	Description	Parameters	Returns
resolve(hostname)	Resolve domain hostname to array of IP address strings	hostname: string	Array<String>

import DNS;

let ips = DNS.resolve("google.com");

for (ip in ips) {
    print("Resolved IP:", ip);
}

---

Record Querying (DNS.query)

Queries specific DNS record types (A, AAAA, MX, TXT, CNAME, NS, PTR, SOA, SRV, CAA).

Function	Description	Parameters	Returns
query(hostname, rtype)	Query specific DNS record type	hostname: string, rtype: string	Array<Object>

Each returned record object contains:

• rec.name: Canonical domain name string.
• rec.type: Record type string (e.g. "A", "MX").
• rec.ttl: Authoritative time-to-live seconds integer.
• rec.data: Strongly typed record data (IP string, target string, or schema object).

Record Schemas (rec.data)

• A / AAAA: IP address string (e.g. "172.217.24.142").
• CNAME / NS / PTR: Canonical hostname string.
• MX: { exchange: String, priority: Number }.
• TXT: Array<String> array of text strings.
• SOA: { primaryNs, respMailbox, serial, refresh, retry, expire, minimumTtl }.
• SRV: { host, port, priority, weight }.
• CAA: { flags, tag, value }.

import DNS;

// Mail Exchange Query
let mxRecords = DNS.query("gmail.com", DNS.Type.MX);
for (rec in mxRecords) {
    print("Exchange:", rec.data.exchange, "| Priority:", rec.data.priority);
}

// Start of Authority Query
let soaRecords = DNS.query("cloudflare.com", DNS.Type.SOA);
for (rec in soaRecords) {
    print("Primary NS:", rec.data.primaryNs, "| Serial:", rec.data.serial);
}

---

Reverse DNS Lookup (DNS.reverseLookup)

Performs reverse DNS lookup over in-addr.arpa or ip6.arpa.

Function	Description	Parameters	Returns
reverseLookup(ipString)	Reverse lookup IP address to host	ipString: string	String

import DNS;

let host = DNS.reverseLookup("8.8.8.8");
print("8.8.8.8 Hostname:", host); // "dns.google"

---

Service Discovery (DNS.discover)

Performs RFC 2782 service discovery over SRV records, returning ordered service endpoints sorted by priority and weight.

Function	Description	Parameters	Returns
discover(serviceName)	Discover service endpoints over SRV	serviceName: string	Array<Object>

import DNS;

let services = DNS.discover("_xmpp-client._tcp.jabber.org");

for (s in services) {
    print("Discovered Endpoint:", s.host, "| Port:", s.port, "| Priority:", s.priority);
}

---

Custom Resolver & Caching (DNS.Resolver())

Construct custom resolvers with upstream server selection and explicit in-memory caching.

import DNS;

let resolver = DNS.Resolver().cache(true);

// 1. First query populates in-memory cache
let r1 = resolver.query("cloudflare.com", DNS.Type.A);
print("Initial Lookup IP:", r1[0].data);

// 2. Second query served directly from cache
let r2 = resolver.query("cloudflare.com", DNS.Type.A);
print("Cached Lookup IP:", r2[0].data);

---

Security Policy Sandboxing (DNS.Policy())

Sandboxes DNS resolution to prevent SSRF (Server-Side Request Forgery) attacks and DNS rebinding to internal subnets.

import DNS;

let policy = DNS.Policy()
    .denyLoopback()
    .denyPrivateNetworks();

print("Configured Security Policy:", policy);