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site: landing page overhaul, blog, benchmarks, numa.rs domain

Browse Source 
Landing page:
- Split features into 3-layer card layout (Block & Protect, Developer Tools, Self-Sovereign DNS)
- Add DoH and conditional forwarding to comparison table
- Fix performance claim (2.3M → 2.0M qps to match benchmarks)
- Add all 3 install methods (brew, cargo, curl)
- Add OG tags + canonical URL for numa.rs
- Fix code block whitespace rendering
- Update roadmap with .onion bridge phase

Blog:
- Add "Building a DNS Resolver from Scratch in Rust" post
- Blog index + template for future posts

Other:
- CNAME for GitHub Pages (numa.rs)
- Benchmark results (bench/results.json)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Razvan Dimescu
2026-03-27 00:30:50 +02:00
parent f8e340ca17
commit 38b5cd2cce
7 changed files with 1977 additions and 110 deletions
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{
"Numa(cold)": {
"avg": 9,
"p50": 9,
"p99": 18,
"min": 8,
"max": 18,
"count": 50
},
"Numa(cached)": {
"avg": 0,
"p50": 0,
"p99": 0,
"min": 0,
"max": 0,
"count": 50
},
"System": {
"avg": 9.1,
"p50": 8,
"p99": 44,
"min": 7,
"max": 44,
"count": 50
},
"Google": {
"avg": 22.4,
"p50": 17,
"p99": 37,
"min": 13,
"max": 37,
"count": 50
},
"Cloudflare": {
"avg": 18.7,
"p50": 14,
"p99": 132,
"min": 12,
"max": 132,
"count": 50
},
"Quad9": {
"avg": 14.5,
"p50": 13,
"p99": 43,
"min": 12,
"max": 43,
"count": 50
}
}

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---
title: I Built a DNS Resolver from Scratch in Rust
description: How DNS actually works at the wire level — label compression, TTL tricks, DoH, and what surprised me building a resolver with zero DNS libraries.
date: March 2026
---
I wanted to understand how DNS actually works. Not the "it translates domain names to IP addresses" explanation — the actual bytes on the wire. What does a DNS packet look like? How does label compression work? Why is everything crammed into 512 bytes?
So I built one from scratch in Rust. No `hickory-dns`, no `trust-dns`, no `simple-dns`. The entire RFC 1035 wire protocol — headers, labels, compression pointers, record types — parsed and serialized by hand. It started as a weekend learning project, became a side project I kept coming back to over 6 years, and eventually turned into [Numa](https://github.com/razvandimescu/numa) — which I now use as my actual system DNS.
A note on terminology before we go further: Numa is currently a *forwarding* resolver — it parses and caches DNS packets, but forwards queries to an upstream (Quad9, Cloudflare, or any DoH provider) rather than walking the delegation chain from root servers itself. Think of it as a smart proxy that does useful things with your DNS traffic locally (caching, ad blocking, overrides, local service domains) before forwarding what it can't answer. Full recursive resolution — where Numa talks directly to root and authoritative nameservers — is on the roadmap, along with DNSSEC validation.
Here's what surprised me along the way.
## What does a DNS packet actually look like?
You can see a real one yourself. Run this:
```bash
dig @127.0.0.1 example.com A +noedns
```
```
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 15242
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;example.com. IN A
;; ANSWER SECTION:
example.com. 53 IN A 104.18.27.120
example.com. 53 IN A 104.18.26.120
```
That's the human-readable version. But what's actually on the wire? A DNS query for `example.com A` is just 29 bytes:
```
ID Flags QCount ACount NSCount ARCount
┌────┐ ┌────┐ ┌────┐ ┌────┐ ┌────┐ ┌────┐
Header: AB CD 01 00 00 01 00 00 00 00 00 00
└────┘ └────┘ └────┘ └────┘ └────┘ └────┘
↑ ↑ ↑
│ │ └─ 1 question, 0 answers, 0 authority, 0 additional
│ └─ Standard query, recursion desired
└─ Random ID (we'll match this in the response)
Question: 07 65 78 61 6D 70 6C 65 03 63 6F 6D 00 00 01 00 01
── ───────────────────── ── ───────── ── ───── ─────
7 e x a m p l e 3 c o m end A IN
↑ ↑ ↑
└─ length prefix └─ length └─ root label (end of name)
```
12 bytes of header + 17 bytes of question = 29 bytes to ask "what's the IP for example.com?" Compare that to an HTTP request for the same information — you'd need hundreds of bytes just for headers.
We can send exactly those bytes and capture what comes back:
```python
python3 -c "
import socket
# Hand-craft a DNS query: header (12 bytes) + question (17 bytes)
q = b'\xab\xcd\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00' # header
q += b'\x07example\x03com\x00\x00\x01\x00\x01' # question
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.sendto(q, ('127.0.0.1', 53))
resp = s.recv(512)
for i in range(0, len(resp), 16):
h = ' '.join(f'{b:02x}' for b in resp[i:i+16])
a = ''.join(chr(b) if 32<=b<127 else '.' for b in resp[i:i+16])
print(f'{i:08x} {h:<48s} {a}')
"
```
```
00000000 ab cd 81 80 00 01 00 02 00 00 00 00 07 65 78 61 .............exa
00000010 6d 70 6c 65 03 63 6f 6d 00 00 01 00 01 07 65 78 mple.com......ex
00000020 61 6d 70 6c 65 03 63 6f 6d 00 00 01 00 01 00 00 ample.com.......
00000030 00 19 00 04 68 12 1b 78 07 65 78 61 6d 70 6c 65 ....h..x.example
00000040 03 63 6f 6d 00 00 01 00 01 00 00 00 19 00 04 68 .com...........h
00000050 12 1a 78 ..x
```
83 bytes back. Let's annotate the response:
```
ID Flags QCount ACount NSCount ARCount
┌────┐ ┌────┐ ┌────┐ ┌────┐ ┌────┐ ┌────┐
Header: AB CD 81 80 00 01 00 02 00 00 00 00
└────┘ └────┘ └────┘ └────┘ └────┘ └────┘
↑ ↑ ↑ ↑
│ │ │ └─ 2 answers
│ │ └─ 1 question (echoed back)
│ └─ Response flag set, recursion available
└─ Same ID as our query
Question: 07 65 78 61 6D 70 6C 65 03 63 6F 6D 00 00 01 00 01
(same as our query — echoed back)
Answer 1: 07 65 78 61 6D 70 6C 65 03 63 6F 6D 00 00 01 00 01
───────────────────────────────────── ── ───── ─────
e x a m p l e . c o m end A IN
00 00 00 19 00 04 68 12 1B 78
─────────── ───── ───────────
TTL: 25s len:4 104.18.27.120
Answer 2: (same domain repeated) 00 01 00 01 00 00 00 19 00 04 68 12 1A 78
───────────
104.18.26.120
```
Notice something wasteful? The domain `example.com` appears *three times* — once in the question, twice in the answers. That's 39 bytes of repeated names in an 83-byte packet. DNS has a solution for this — but first, the overall structure.
The whole thing fits in a single UDP datagram. The structure is:
```
+--+--+--+--+--+--+--+--+
| Header | 12 bytes: ID, flags, counts
+--+--+--+--+--+--+--+--+
| Questions | What you're asking
+--+--+--+--+--+--+--+--+
| Answers | The response records
+--+--+--+--+--+--+--+--+
| Authorities | NS records for the zone
+--+--+--+--+--+--+--+--+
| Additional | Extra helpful records
+--+--+--+--+--+--+--+--+
```
In Rust, parsing the header is just reading 12 bytes and unpacking the flags:
```rust
pub fn read(buffer: &mut BytePacketBuffer) -> Result<DnsHeader> {
let id = buffer.read_u16()?;
let flags = buffer.read_u16()?;
// Flags pack 9 fields into 16 bits
let recursion_desired = (flags & (1 << 8)) > 0;
let truncated_message = (flags & (1 << 9)) > 0;
let authoritative_answer = (flags & (1 << 10)) > 0;
let opcode = (flags >> 11) & 0x0F;
let response = (flags & (1 << 15)) > 0;
// ... and so on
}
```
No padding, no alignment, no JSON overhead. DNS was designed in 1987 when every byte counted, and honestly? The wire format is kind of beautiful in its efficiency.
## Label compression is the clever part
Remember how `example.com` appeared three times in that 83-byte response? Domain names in DNS are stored as a sequence of **labels** — length-prefixed segments:
```
example.com → [7]example[3]com[0]
```
The `[7]` means "the next 7 bytes are a label." The `[0]` is the root label (end of name). That's 13 bytes per occurrence, 39 bytes for three repetitions. In a response with authority and additional records, domain names can account for half the packet.
DNS solves this with **compression pointers** — if the top two bits of a length byte are `11`, the remaining 14 bits are an offset back into the packet where the rest of the name can be found. A well-compressed version of our response would replace the answer names with `C0 0C` — a 2-byte pointer to offset 12 where `example.com` first appears in the question section. That turns 39 bytes of names into 15 (13 + 2 + 2). Our upstream didn't bother compressing, but many do — especially when related domains appear:
```
Offset 0x20: [6]google[3]com[0] ← full name
Offset 0x40: [4]mail[0xC0][0x20] ← "mail" + pointer to offset 0x20
Offset 0x50: [3]www[0xC0][0x20] ← "www" + pointer to offset 0x20
```
Pointers can chain — a pointer can point to another pointer. Parsing this correctly requires tracking your position in the buffer and handling jumps:
```rust
pub fn read_qname(&mut self, outstr: &mut String) -> Result<()> {
let mut pos = self.pos();
let mut jumped = false;
let mut delim = "";
loop {
let len = self.get(pos)?;
// Top two bits set = compression pointer
if (len & 0xC0) == 0xC0 {
if !jumped {
self.seek(pos + 2)?; // advance past the pointer
}
let offset = (((len as u16) ^ 0xC0) << 8) | self.get(pos + 1)? as u16;
pos = offset as usize;
jumped = true;
continue;
}
pos += 1;
if len == 0 { break; } // root label
outstr.push_str(delim);
outstr.push_str(&self.get_range(pos, len as usize)?
.iter().map(|&b| b as char).collect::<String>());
delim = ".";
pos += len as usize;
}
if !jumped {
self.seek(pos)?;
}
Ok(())
}
```
This one bit me: when you follow a pointer, you must *not* advance the buffer's read position past where you jumped from. The pointer is 2 bytes, so you advance by 2, but the actual label data lives elsewhere in the packet. If you follow the pointer and also advance past it, you'll skip over the next record entirely. I spent a fun evening debugging that one.
## TTL adjustment on read, not write
This is my favorite trick in the whole codebase. I initially stored the remaining TTL and decremented it, which meant I needed a background thread to sweep expired entries. It worked, but it felt wrong — too much machinery for something simple.
The cleaner approach: store the original TTL and the timestamp when the record was cached. On read, compute `remaining = original_ttl - elapsed`. If it's zero or negative, the entry is stale — evict it lazily.
```rust
pub fn lookup(&mut self, domain: &str, qtype: QueryType) -> Option<DnsPacket> {
let key = (domain.to_lowercase(), qtype);
let entry = self.entries.get(&key)?;
let elapsed = entry.cached_at.elapsed().as_secs() as u32;
if elapsed >= entry.original_ttl {
self.entries.remove(&key);
return None;
}
// Adjust TTLs in the response to reflect remaining time
let mut packet = entry.packet.clone();
for answer in &mut packet.answers {
answer.set_ttl(entry.original_ttl.saturating_sub(elapsed));
}
Some(packet)
}
```
No background thread. No timer. Entries expire lazily. The cache stays consistent because every consumer sees the adjusted TTL.
## Async per-query with tokio
Each incoming UDP packet spawns a tokio task. The main loop never blocks:
```rust
loop {
let mut buffer = BytePacketBuffer::new();
let (_, src_addr) = socket.recv_from(&mut buffer.buf).await?;
let ctx = Arc::clone(&ctx);
tokio::spawn(async move {
if let Err(e) = handle_query(buffer, src_addr, &ctx).await {
error!("{} | HANDLER ERROR | {}", src_addr, e);
}
});
}
```
Each `handle_query` walks a pipeline. This is the part where "from scratch" pays off — every step is just a function that either returns a response or says "not my problem, pass it on":
```
┌─────────────────────────────────────────────────────┐
│ Numa Resolution Pipeline │
└─────────────────────────────────────────────────────┘
Query ──→ Overrides ──→ .numa TLD ──→ Blocklist ──→ Zones ──→ Cache ──→ DoH
│ │ │ │ │ │ │
│ │ match? │ match? │ blocked? │ match? │ hit? │
│ ↓ ↓ ↓ ↓ ↓ ↓
│ respond respond 0.0.0.0 respond respond forward
│ (auto-reverts (reverse (ad gone) (static (TTL to upstream
│ after N min) proxy+TLS) records) adjusted) (encrypted)
│
└──→ Each step either answers or passes to the next.
Adding a feature = inserting a function into this chain.
```
Want conditional forwarding for Tailscale? Insert a step before the upstream that checks the domain suffix. Want to override `api.example.com` for 5 minutes while debugging? Insert an entry in the overrides step — it auto-expires and the domain goes back to resolving normally. A DNS library would have hidden this pipeline behind an opaque `resolve()` call.
This is one of those cases where Rust + tokio makes things almost embarrassingly simple. In a synchronous resolver, you'd need a thread pool or hand-rolled event loop. Here, each query is a lightweight future. A slow upstream query doesn't block anything — other queries keep flowing.
## DNS-over-HTTPS: the "wait, that's it?" moment
The most recent addition, and honestly the one that surprised me with how little code it needed. DoH (RFC 8484) is conceptually simple: take the exact same DNS wire-format packet you'd send over UDP, POST it to an HTTPS endpoint with `Content-Type: application/dns-message`, and parse the response the same way. Same bytes, different transport.
```rust
async fn forward_doh(
query: &DnsPacket,
url: &str,
client: &reqwest::Client,
timeout_duration: Duration,
) -> Result<DnsPacket> {
let mut send_buffer = BytePacketBuffer::new();
query.write(&mut send_buffer)?;
let resp = timeout(timeout_duration, client
.post(url)
.header("content-type", "application/dns-message")
.header("accept", "application/dns-message")
.body(send_buffer.filled().to_vec())
.send())
.await??.error_for_status()?;
let bytes = resp.bytes().await?;
let mut recv_buffer = BytePacketBuffer::from_bytes(&bytes);
DnsPacket::from_buffer(&mut recv_buffer)
}
```
The one gotcha that cost me an hour: Quad9 and other DoH providers require HTTP/2. My first attempt used HTTP/1.1 and got a cryptic 400 Bad Request. Adding the `http2` feature to reqwest fixed it. The upside of HTTP/2? Connection multiplexing means subsequent queries reuse the TLS session — ~16ms vs ~50ms for the first query. Free performance.
The `Upstream` enum dispatches between UDP and DoH based on the URL scheme:
```rust
pub enum Upstream {
Udp(SocketAddr),
Doh { url: String, client: reqwest::Client },
}
```
If the configured address starts with `https://`, it's DoH. Otherwise, plain UDP. Simple, no toggles.
## "Why not just use dnsmasq + nginx + mkcert?"
Fair question — I got this a lot when I first [posted about Numa](https://www.reddit.com/r/programare/). And the answer is: you absolutely can. Those are mature, battle-tested tools.
The difference is integration. With dnsmasq + nginx + mkcert, you're configuring three tools: DNS resolution, reverse proxy rules, and certificate generation. Each has its own config format, its own lifecycle, its own failure modes. Numa puts the DNS record, the reverse proxy, and the TLS cert behind a single API call:
```bash
curl -X POST localhost:5380/services -d '{"name":"frontend","target_port":5173}'
```
That creates the DNS entry, generates a TLS certificate with the correct SAN, and starts proxying — including WebSocket upgrade for Vite HMR. One command, no config files.
There's also a distinction people miss: **mkcert and certbot solve different problems.** Certbot issues certificates for public domains via Let's Encrypt — it needs DNS validation or an open port 80. Numa generates certificates for `.numa` domains that don't exist publicly. You can't get a Let's Encrypt cert for `frontend.numa`. They're complementary, not alternatives.
Someone on Reddit told me the real value is "TLS termination + reverse proxy, simple to install, for developers — stop there." Honestly, they might be right about focus. But DNS is the foundation the proxy sits on, and having full control over the resolution pipeline is what makes auto-revert overrides and LAN discovery possible. Sometimes the "unnecessary" part is what makes the interesting part work.
## The blocklist memory problem
Numa's ad blocking loads the [Hagezi Pro](https://github.com/hagezi/dns-blocklists) list at startup — ~385,000 domains stored in a `HashSet<String>`. This works, but it consumes ~30MB of memory. For a laptop DNS proxy, that's fine. For embedded devices or a future where you want to run Numa on a router, it's too much.
The obvious optimization is a **Bloom filter** — a probabilistic data structure that can tell you "definitely not in the set" or "probably in the set" using a fraction of the memory. A Bloom filter for 385K domains with a 0.1% false positive rate would use ~700KB instead of 30MB. The false positives (0.1% of queries hitting domains not in the list) would be blocked unnecessarily, which is acceptable for ad blocking.
I haven't implemented this yet — the `HashSet` is simple, correct, and 30MB is nothing on a laptop. But if Numa ever needs to run on a router or a Raspberry Pi, this is the first optimization I'd reach for.
## What I learned
**DNS is a 40-year-old protocol that works remarkably well.** The wire format is tight, the caching model is elegant, and the hierarchical delegation system has scaled to billions of queries per day. The things people complain about (DNSSEC complexity, lack of encryption) are extensions bolted on decades later, not flaws in the original design.
**"From scratch" gives you full control.** When I wanted to add ephemeral overrides that auto-revert, it was trivial — just a new step in the resolution pipeline. Conditional forwarding for Tailscale/VPN? Another step. Every feature is a function that takes a query and returns either a response or "pass to the next stage." A DNS library would have hidden this pipeline.
**The hard parts aren't where you'd expect.** Parsing the wire protocol was straightforward (RFC 1035 is well-written). The hard parts were: browsers rejecting wildcard certs under single-label TLDs (`*.numa` fails — you need per-service SANs), macOS resolver quirks (scutil vs /etc/resolv.conf), and getting multiple processes to bind the same multicast port (`SO_REUSEPORT` on macOS, `SO_REUSEADDR` on Linux).
**Terminology will get you roasted.** I initially called Numa a "DNS resolver" and got corrected on Reddit — it's a forwarding resolver (DNS proxy). It doesn't walk the delegation chain from root servers; it forwards to an upstream. The distinction matters to people who work with DNS for a living, and being sloppy about it cost me credibility in my first community posts. If you're building in a domain with established terminology, learn the vocabulary before you show up.
## What's next
Numa is at v0.5.0 with DNS forwarding, caching, ad blocking, DNS-over-HTTPS, .numa local domains with auto TLS, and LAN service discovery.
On the roadmap:
- **DoT (DNS-over-TLS)** — DoH was first because it passes through captive portals and corporate firewalls (port 443 vs 853). DoT has less framing overhead, so it's faster. Both will be available.
- **Recursive resolution** — walk the delegation chain from root servers instead of forwarding. Combined with DNSSEC validation, this removes the need to trust any upstream resolver.
- **[pkarr](https://github.com/pubky/pkarr) integration** — self-sovereign DNS via the Mainline BitTorrent DHT. Publish DNS records signed with your Ed25519 key, no registrar needed.
But those are rabbit holes for future posts.
[github.com/razvandimescu/numa](https://github.com/razvandimescu/numa)

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numa.rs

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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>$title$ — Numa</title>
<meta name="description" content="$description$">
<link rel="preconnect" href="https://fonts.googleapis.com">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link href="https://fonts.googleapis.com/css2?family=Instrument+Serif:ital@0;1&family=DM+Sans:ital,opsz,wght@0,9..40,400;0,9..40,500;0,9..40,600;1,9..40,400&family=JetBrains+Mono:wght@400;500&display=swap" rel="stylesheet">
<style>
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
:root {
--bg-deep: #f5f0e8;
--bg-surface: #ece5da;
--bg-elevated: #e3dbce;
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--font-display: 'Instrument Serif', Georgia, serif;
--font-body: 'DM Sans', system-ui, sans-serif;
--font-mono: 'JetBrains Mono', monospace;
}
html { scroll-behavior: smooth; }
body {
background: var(--bg-deep);
color: var(--text-primary);
font-family: var(--font-body);
font-weight: 400;
line-height: 1.7;
-webkit-font-smoothing: antialiased;
}
body::before {
content: '';
position: fixed;
inset: 0;
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pointer-events: none;
z-index: 9999;
}
/* --- Blog nav --- */
.blog-nav {
padding: 1.5rem 2rem;
display: flex;
align-items: center;
gap: 1.5rem;
}
.blog-nav a {
font-family: var(--font-mono);
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letter-spacing: 0.08em;
text-transform: uppercase;
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font-size: 0.75rem;
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}
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font-weight: 600;
font-size: 1.8rem;
line-height: 1.2;
margin: 3rem 0 1rem;
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font-weight: 600;
font-size: 1.2rem;
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<h1>I Built a DNS Resolver from Scratch in Rust</h1>
<div class="article-meta">
March 2026 · <a href="https://dimescu.ro">Razvan Dimescu</a>
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</header>
<p>I wanted to understand how DNS actually works. Not the “it translates
domain names to IP addresses” explanation — the actual bytes on the
wire. What does a DNS packet look like? How does label compression work?
Why is everything crammed into 512 bytes?</p>
<p>So I built one from scratch in Rust. No <code>hickory-dns</code>, no
<code>trust-dns</code>, no <code>simple-dns</code>. The entire RFC 1035
wire protocol — headers, labels, compression pointers, record types —
parsed and serialized by hand. It started as a weekend learning project,
became a side project I kept coming back to over 6 years, and eventually
turned into <a href="https://github.com/razvandimescu/numa">Numa</a> —
which I now use as my actual system DNS.</p>
<p>A note on terminology before we go further: Numa is currently a
<em>forwarding</em> resolver — it parses and caches DNS packets, but
forwards queries to an upstream (Quad9, Cloudflare, or any DoH provider)
rather than walking the delegation chain from root servers itself. Think
of it as a smart proxy that does useful things with your DNS traffic
locally (caching, ad blocking, overrides, local service domains) before
forwarding what it can’t answer. Full recursive resolution — where Numa
talks directly to root and authoritative nameservers — is on the
roadmap, along with DNSSEC validation.</p>
<p>Here’s what surprised me along the way.</p>
<h2 id="what-does-a-dns-packet-actually-look-like">What does a DNS
packet actually look like?</h2>
<p>You can see a real one yourself. Run this:</p>
<div class="sourceCode" id="cb1"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="ex">dig</span> @127.0.0.1 example.com A +noedns</span></code></pre></div>
<pre><code>;; -&gt;&gt;HEADER&lt;&lt;- opcode: QUERY, status: NOERROR, id: 15242
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;example.com. IN A
;; ANSWER SECTION:
example.com. 53 IN A 104.18.27.120
example.com. 53 IN A 104.18.26.120</code></pre>
<p>That’s the human-readable version. But what’s actually on the wire? A
DNS query for <code>example.com A</code> is just 29 bytes:</p>
<pre><code> ID Flags QCount ACount NSCount ARCount
┌────┐ ┌────┐ ┌────┐ ┌────┐ ┌────┐ ┌────┐
Header: AB CD 01 00 00 01 00 00 00 00 00 00
└────┘ └────┘ └────┘ └────┘ └────┘ └────┘
↑ ↑ ↑
│ │ └─ 1 question, 0 answers, 0 authority, 0 additional
│ └─ Standard query, recursion desired
└─ Random ID (we&#39;ll match this in the response)
Question: 07 65 78 61 6D 70 6C 65 03 63 6F 6D 00 00 01 00 01
── ───────────────────── ── ───────── ── ───── ─────
7 e x a m p l e 3 c o m end A IN
↑ ↑ ↑
└─ length prefix └─ length └─ root label (end of name)</code></pre>
<p>12 bytes of header + 17 bytes of question = 29 bytes to ask “what’s
the IP for example.com?” Compare that to an HTTP request for the same
information — you’d need hundreds of bytes just for headers.</p>
<p>We can send exactly those bytes and capture what comes back:</p>
<div class="sourceCode" id="cb4"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>python3 <span class="op">-</span>c <span class="st">&quot;</span></span>
<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="er">import socket</span></span>
<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a><span class="co"># Hand-craft a DNS query: header (12 bytes) + question (17 bytes)</span></span>
<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a>q <span class="op">=</span> <span class="st">b&#39;</span><span class="ch">\xab\xcd\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00</span><span class="st">&#39;</span> <span class="co"># header</span></span>
<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a>q <span class="op">+=</span> <span class="st">b&#39;</span><span class="ch">\x07</span><span class="st">example</span><span class="ch">\x03</span><span class="st">com</span><span class="ch">\x00\x00\x01\x00\x01</span><span class="st">&#39;</span> <span class="co"># question</span></span>
<span id="cb4-6"><a href="#cb4-6" aria-hidden="true" tabindex="-1"></a>s <span class="op">=</span> socket.socket(socket.AF_INET, socket.SOCK_DGRAM)</span>
<span id="cb4-7"><a href="#cb4-7" aria-hidden="true" tabindex="-1"></a>s.sendto(q, (<span class="st">&#39;127.0.0.1&#39;</span>, <span class="dv">53</span>))</span>
<span id="cb4-8"><a href="#cb4-8" aria-hidden="true" tabindex="-1"></a>resp <span class="op">=</span> s.recv(<span class="dv">512</span>)</span>
<span id="cb4-9"><a href="#cb4-9" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="bu">len</span>(resp), <span class="dv">16</span>):</span>
<span id="cb4-10"><a href="#cb4-10" aria-hidden="true" tabindex="-1"></a> h <span class="op">=</span> <span class="st">&#39; &#39;</span>.join(<span class="ss">f&#39;</span><span class="sc">{</span>b<span class="sc">:02x}</span><span class="ss">&#39;</span> <span class="cf">for</span> b <span class="kw">in</span> resp[i:i<span class="op">+</span><span class="dv">16</span>])</span>
<span id="cb4-11"><a href="#cb4-11" aria-hidden="true" tabindex="-1"></a> a <span class="op">=</span> <span class="st">&#39;&#39;</span>.join(<span class="bu">chr</span>(b) <span class="cf">if</span> <span class="dv">32</span><span class="op">&lt;=</span>b<span class="op">&lt;</span><span class="dv">127</span> <span class="cf">else</span> <span class="st">&#39;.&#39;</span> <span class="cf">for</span> b <span class="kw">in</span> resp[i:i<span class="op">+</span><span class="dv">16</span>])</span>
<span id="cb4-12"><a href="#cb4-12" aria-hidden="true" tabindex="-1"></a> <span class="bu">print</span>(<span class="ss">f&#39;</span><span class="sc">{</span>i<span class="sc">:08x}</span><span class="ss"> </span><span class="sc">{</span>h<span class="sc">:&lt;48s}</span><span class="ss"> </span><span class="sc">{</span>a<span class="sc">}</span><span class="ss">&#39;</span>)</span>
<span id="cb4-13"><a href="#cb4-13" aria-hidden="true" tabindex="-1"></a><span class="co">&quot;</span></span></code></pre></div>
<pre><code>00000000 ab cd 81 80 00 01 00 02 00 00 00 00 07 65 78 61 .............exa
00000010 6d 70 6c 65 03 63 6f 6d 00 00 01 00 01 07 65 78 mple.com......ex
00000020 61 6d 70 6c 65 03 63 6f 6d 00 00 01 00 01 00 00 ample.com.......
00000030 00 19 00 04 68 12 1b 78 07 65 78 61 6d 70 6c 65 ....h..x.example
00000040 03 63 6f 6d 00 00 01 00 01 00 00 00 19 00 04 68 .com...........h
00000050 12 1a 78 ..x</code></pre>
<p>83 bytes back. Let’s annotate the response:</p>
<pre><code> ID Flags QCount ACount NSCount ARCount
┌────┐ ┌────┐ ┌────┐ ┌────┐ ┌────┐ ┌────┐
Header: AB CD 81 80 00 01 00 02 00 00 00 00
└────┘ └────┘ └────┘ └────┘ └────┘ └────┘
↑ ↑ ↑ ↑
│ │ │ └─ 2 answers
│ │ └─ 1 question (echoed back)
│ └─ Response flag set, recursion available
└─ Same ID as our query
Question: 07 65 78 61 6D 70 6C 65 03 63 6F 6D 00 00 01 00 01
(same as our query — echoed back)
Answer 1: 07 65 78 61 6D 70 6C 65 03 63 6F 6D 00 00 01 00 01
───────────────────────────────────── ── ───── ─────
e x a m p l e . c o m end A IN
00 00 00 19 00 04 68 12 1B 78
─────────── ───── ───────────
TTL: 25s len:4 104.18.27.120
Answer 2: (same domain repeated) 00 01 00 01 00 00 00 19 00 04 68 12 1A 78
───────────
104.18.26.120</code></pre>
<p>Notice something wasteful? The domain <code>example.com</code>
appears <em>three times</em> — once in the question, twice in the
answers. That’s 39 bytes of repeated names in an 83-byte packet. DNS has
a solution for this — but first, the overall structure.</p>
<p>The whole thing fits in a single UDP datagram. The structure is:</p>
<pre><code>+--+--+--+--+--+--+--+--+
| Header | 12 bytes: ID, flags, counts
+--+--+--+--+--+--+--+--+
| Questions | What you&#39;re asking
+--+--+--+--+--+--+--+--+
| Answers | The response records
+--+--+--+--+--+--+--+--+
| Authorities | NS records for the zone
+--+--+--+--+--+--+--+--+
| Additional | Extra helpful records
+--+--+--+--+--+--+--+--+</code></pre>
<p>In Rust, parsing the header is just reading 12 bytes and unpacking
the flags:</p>
<div class="sourceCode" id="cb8"><pre
class="sourceCode rust"><code class="sourceCode rust"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="kw">pub</span> <span class="kw">fn</span> read(buffer<span class="op">:</span> <span class="op">&amp;</span><span class="kw">mut</span> BytePacketBuffer) <span class="op">-&gt;</span> <span class="dt">Result</span><span class="op">&lt;</span>DnsHeader<span class="op">&gt;</span> <span class="op">{</span></span>
<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> id <span class="op">=</span> buffer<span class="op">.</span>read_u16()<span class="op">?;</span></span>
<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> flags <span class="op">=</span> buffer<span class="op">.</span>read_u16()<span class="op">?;</span></span>
<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a> <span class="co">// Flags pack 9 fields into 16 bits</span></span>
<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> recursion_desired <span class="op">=</span> (flags <span class="op">&amp;</span> (<span class="dv">1</span> <span class="op">&lt;&lt;</span> <span class="dv">8</span>)) <span class="op">&gt;</span> <span class="dv">0</span><span class="op">;</span></span>
<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> truncated_message <span class="op">=</span> (flags <span class="op">&amp;</span> (<span class="dv">1</span> <span class="op">&lt;&lt;</span> <span class="dv">9</span>)) <span class="op">&gt;</span> <span class="dv">0</span><span class="op">;</span></span>
<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> authoritative_answer <span class="op">=</span> (flags <span class="op">&amp;</span> (<span class="dv">1</span> <span class="op">&lt;&lt;</span> <span class="dv">10</span>)) <span class="op">&gt;</span> <span class="dv">0</span><span class="op">;</span></span>
<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> opcode <span class="op">=</span> (flags <span class="op">&gt;&gt;</span> <span class="dv">11</span>) <span class="op">&amp;</span> <span class="dv">0x0F</span><span class="op">;</span></span>
<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> response <span class="op">=</span> (flags <span class="op">&amp;</span> (<span class="dv">1</span> <span class="op">&lt;&lt;</span> <span class="dv">15</span>)) <span class="op">&gt;</span> <span class="dv">0</span><span class="op">;</span></span>
<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a> <span class="co">// ... and so on</span></span>
<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<p>No padding, no alignment, no JSON overhead. DNS was designed in 1987
when every byte counted, and honestly? The wire format is kind of
beautiful in its efficiency.</p>
<h2 id="label-compression-is-the-clever-part">Label compression is the
clever part</h2>
<p>Remember how <code>example.com</code> appeared three times in that
83-byte response? Domain names in DNS are stored as a sequence of
<strong>labels</strong> — length-prefixed segments:</p>
<pre><code>example.com → [7]example[3]com[0]</code></pre>
<p>The <code>[7]</code> means “the next 7 bytes are a label.” The
<code>[0]</code> is the root label (end of name). That’s 13 bytes per
occurrence, 39 bytes for three repetitions. In a response with authority
and additional records, domain names can account for half the
packet.</p>
<p>DNS solves this with <strong>compression pointers</strong> — if the
top two bits of a length byte are <code>11</code>, the remaining 14 bits
are an offset back into the packet where the rest of the name can be
found. A well-compressed version of our response would replace the
answer names with <code>C0 0C</code> — a 2-byte pointer to offset 12
where <code>example.com</code> first appears in the question section.
That turns 39 bytes of names into 15 (13 + 2 + 2). Our upstream didn’t
bother compressing, but many do — especially when related domains
appear:</p>
<pre><code>Offset 0x20: [6]google[3]com[0] ← full name
Offset 0x40: [4]mail[0xC0][0x20] ← &quot;mail&quot; + pointer to offset 0x20
Offset 0x50: [3]www[0xC0][0x20] ← &quot;www&quot; + pointer to offset 0x20</code></pre>
<p>Pointers can chain — a pointer can point to another pointer. Parsing
this correctly requires tracking your position in the buffer and
handling jumps:</p>
<div class="sourceCode" id="cb11"><pre
class="sourceCode rust"><code class="sourceCode rust"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="kw">pub</span> <span class="kw">fn</span> read_qname(<span class="op">&amp;</span><span class="kw">mut</span> <span class="kw">self</span><span class="op">,</span> outstr<span class="op">:</span> <span class="op">&amp;</span><span class="kw">mut</span> <span class="dt">String</span>) <span class="op">-&gt;</span> <span class="dt">Result</span><span class="op">&lt;</span>()<span class="op">&gt;</span> <span class="op">{</span></span>
<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> <span class="kw">mut</span> pos <span class="op">=</span> <span class="kw">self</span><span class="op">.</span>pos()<span class="op">;</span></span>
<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> <span class="kw">mut</span> jumped <span class="op">=</span> <span class="cn">false</span><span class="op">;</span></span>
<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> <span class="kw">mut</span> delim <span class="op">=</span> <span class="st">&quot;&quot;</span><span class="op">;</span></span>
<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a> <span class="cf">loop</span> <span class="op">{</span></span>
<span id="cb11-7"><a href="#cb11-7" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> len <span class="op">=</span> <span class="kw">self</span><span class="op">.</span>get(pos)<span class="op">?;</span></span>
<span id="cb11-8"><a href="#cb11-8" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb11-9"><a href="#cb11-9" aria-hidden="true" tabindex="-1"></a> <span class="co">// Top two bits set = compression pointer</span></span>
<span id="cb11-10"><a href="#cb11-10" aria-hidden="true" tabindex="-1"></a> <span class="cf">if</span> (len <span class="op">&amp;</span> <span class="dv">0xC0</span>) <span class="op">==</span> <span class="dv">0xC0</span> <span class="op">{</span></span>
<span id="cb11-11"><a href="#cb11-11" aria-hidden="true" tabindex="-1"></a> <span class="cf">if</span> <span class="op">!</span>jumped <span class="op">{</span></span>
<span id="cb11-12"><a href="#cb11-12" aria-hidden="true" tabindex="-1"></a> <span class="kw">self</span><span class="op">.</span>seek(pos <span class="op">+</span> <span class="dv">2</span>)<span class="op">?;</span> <span class="co">// advance past the pointer</span></span>
<span id="cb11-13"><a href="#cb11-13" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span></span>
<span id="cb11-14"><a href="#cb11-14" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> offset <span class="op">=</span> (((len <span class="kw">as</span> <span class="dt">u16</span>) <span class="op">^</span> <span class="dv">0xC0</span>) <span class="op">&lt;&lt;</span> <span class="dv">8</span>) <span class="op">|</span> <span class="kw">self</span><span class="op">.</span>get(pos <span class="op">+</span> <span class="dv">1</span>)<span class="op">?</span> <span class="kw">as</span> <span class="dt">u16</span><span class="op">;</span></span>
<span id="cb11-15"><a href="#cb11-15" aria-hidden="true" tabindex="-1"></a> pos <span class="op">=</span> offset <span class="kw">as</span> <span class="dt">usize</span><span class="op">;</span></span>
<span id="cb11-16"><a href="#cb11-16" aria-hidden="true" tabindex="-1"></a> jumped <span class="op">=</span> <span class="cn">true</span><span class="op">;</span></span>
<span id="cb11-17"><a href="#cb11-17" aria-hidden="true" tabindex="-1"></a> <span class="cf">continue</span><span class="op">;</span></span>
<span id="cb11-18"><a href="#cb11-18" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span></span>
<span id="cb11-19"><a href="#cb11-19" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb11-20"><a href="#cb11-20" aria-hidden="true" tabindex="-1"></a> pos <span class="op">+=</span> <span class="dv">1</span><span class="op">;</span></span>
<span id="cb11-21"><a href="#cb11-21" aria-hidden="true" tabindex="-1"></a> <span class="cf">if</span> len <span class="op">==</span> <span class="dv">0</span> <span class="op">{</span> <span class="cf">break</span><span class="op">;</span> <span class="op">}</span> <span class="co">// root label</span></span>
<span id="cb11-22"><a href="#cb11-22" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb11-23"><a href="#cb11-23" aria-hidden="true" tabindex="-1"></a> outstr<span class="op">.</span>push_str(delim)<span class="op">;</span></span>
<span id="cb11-24"><a href="#cb11-24" aria-hidden="true" tabindex="-1"></a> outstr<span class="op">.</span>push_str(<span class="op">&amp;</span><span class="kw">self</span><span class="op">.</span>get_range(pos<span class="op">,</span> len <span class="kw">as</span> <span class="dt">usize</span>)<span class="op">?</span></span>
<span id="cb11-25"><a href="#cb11-25" aria-hidden="true" tabindex="-1"></a> <span class="op">.</span>iter()<span class="op">.</span>map(<span class="op">|&amp;</span>b<span class="op">|</span> b <span class="kw">as</span> <span class="dt">char</span>)<span class="op">.</span><span class="pp">collect::</span><span class="op">&lt;</span><span class="dt">String</span><span class="op">&gt;</span>())<span class="op">;</span></span>
<span id="cb11-26"><a href="#cb11-26" aria-hidden="true" tabindex="-1"></a> delim <span class="op">=</span> <span class="st">&quot;.&quot;</span><span class="op">;</span></span>
<span id="cb11-27"><a href="#cb11-27" aria-hidden="true" tabindex="-1"></a> pos <span class="op">+=</span> len <span class="kw">as</span> <span class="dt">usize</span><span class="op">;</span></span>
<span id="cb11-28"><a href="#cb11-28" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span></span>
<span id="cb11-29"><a href="#cb11-29" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb11-30"><a href="#cb11-30" aria-hidden="true" tabindex="-1"></a> <span class="cf">if</span> <span class="op">!</span>jumped <span class="op">{</span></span>
<span id="cb11-31"><a href="#cb11-31" aria-hidden="true" tabindex="-1"></a> <span class="kw">self</span><span class="op">.</span>seek(pos)<span class="op">?;</span></span>
<span id="cb11-32"><a href="#cb11-32" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span></span>
<span id="cb11-33"><a href="#cb11-33" aria-hidden="true" tabindex="-1"></a> <span class="cn">Ok</span>(())</span>
<span id="cb11-34"><a href="#cb11-34" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<p>This one bit me: when you follow a pointer, you must <em>not</em>
advance the buffer’s read position past where you jumped from. The
pointer is 2 bytes, so you advance by 2, but the actual label data lives
elsewhere in the packet. If you follow the pointer and also advance past
it, you’ll skip over the next record entirely. I spent a fun evening
debugging that one.</p>
<h2 id="ttl-adjustment-on-read-not-write">TTL adjustment on read, not
write</h2>
<p>This is my favorite trick in the whole codebase. I initially stored
the remaining TTL and decremented it, which meant I needed a background
thread to sweep expired entries. It worked, but it felt wrong — too much
machinery for something simple.</p>
<p>The cleaner approach: store the original TTL and the timestamp when
the record was cached. On read, compute
<code>remaining = original_ttl - elapsed</code>. If it’s zero or
negative, the entry is stale — evict it lazily.</p>
<div class="sourceCode" id="cb12"><pre
class="sourceCode rust"><code class="sourceCode rust"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="kw">pub</span> <span class="kw">fn</span> lookup(<span class="op">&amp;</span><span class="kw">mut</span> <span class="kw">self</span><span class="op">,</span> domain<span class="op">:</span> <span class="op">&amp;</span><span class="dt">str</span><span class="op">,</span> qtype<span class="op">:</span> QueryType) <span class="op">-&gt;</span> <span class="dt">Option</span><span class="op">&lt;</span>DnsPacket<span class="op">&gt;</span> <span class="op">{</span></span>
<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> key <span class="op">=</span> (domain<span class="op">.</span>to_lowercase()<span class="op">,</span> qtype)<span class="op">;</span></span>
<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> entry <span class="op">=</span> <span class="kw">self</span><span class="op">.</span>entries<span class="op">.</span>get(<span class="op">&amp;</span>key)<span class="op">?;</span></span>
<span id="cb12-4"><a href="#cb12-4" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> elapsed <span class="op">=</span> entry<span class="op">.</span>cached_at<span class="op">.</span>elapsed()<span class="op">.</span>as_secs() <span class="kw">as</span> <span class="dt">u32</span><span class="op">;</span></span>
<span id="cb12-5"><a href="#cb12-5" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb12-6"><a href="#cb12-6" aria-hidden="true" tabindex="-1"></a> <span class="cf">if</span> elapsed <span class="op">&gt;=</span> entry<span class="op">.</span>original_ttl <span class="op">{</span></span>
<span id="cb12-7"><a href="#cb12-7" aria-hidden="true" tabindex="-1"></a> <span class="kw">self</span><span class="op">.</span>entries<span class="op">.</span>remove(<span class="op">&amp;</span>key)<span class="op">;</span></span>
<span id="cb12-8"><a href="#cb12-8" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> <span class="cn">None</span><span class="op">;</span></span>
<span id="cb12-9"><a href="#cb12-9" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span></span>
<span id="cb12-10"><a href="#cb12-10" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb12-11"><a href="#cb12-11" aria-hidden="true" tabindex="-1"></a> <span class="co">// Adjust TTLs in the response to reflect remaining time</span></span>
<span id="cb12-12"><a href="#cb12-12" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> <span class="kw">mut</span> packet <span class="op">=</span> entry<span class="op">.</span>packet<span class="op">.</span>clone()<span class="op">;</span></span>
<span id="cb12-13"><a href="#cb12-13" aria-hidden="true" tabindex="-1"></a> <span class="cf">for</span> answer <span class="kw">in</span> <span class="op">&amp;</span><span class="kw">mut</span> packet<span class="op">.</span>answers <span class="op">{</span></span>
<span id="cb12-14"><a href="#cb12-14" aria-hidden="true" tabindex="-1"></a> answer<span class="op">.</span>set_ttl(entry<span class="op">.</span>original_ttl<span class="op">.</span>saturating_sub(elapsed))<span class="op">;</span></span>
<span id="cb12-15"><a href="#cb12-15" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span></span>
<span id="cb12-16"><a href="#cb12-16" aria-hidden="true" tabindex="-1"></a> <span class="cn">Some</span>(packet)</span>
<span id="cb12-17"><a href="#cb12-17" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<p>No background thread. No timer. Entries expire lazily. The cache
stays consistent because every consumer sees the adjusted TTL.</p>
<h2 id="async-per-query-with-tokio">Async per-query with tokio</h2>
<p>Each incoming UDP packet spawns a tokio task. The main loop never
blocks:</p>
<div class="sourceCode" id="cb13"><pre
class="sourceCode rust"><code class="sourceCode rust"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="cf">loop</span> <span class="op">{</span></span>
<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> <span class="kw">mut</span> buffer <span class="op">=</span> <span class="pp">BytePacketBuffer::</span>new()<span class="op">;</span></span>
<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> (_<span class="op">,</span> src_addr) <span class="op">=</span> socket<span class="op">.</span>recv_from(<span class="op">&amp;</span><span class="kw">mut</span> buffer<span class="op">.</span>buf)<span class="op">.</span><span class="kw">await</span><span class="op">?;</span></span>
<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> ctx <span class="op">=</span> <span class="pp">Arc::</span>clone(<span class="op">&amp;</span>ctx)<span class="op">;</span></span>
<span id="cb13-6"><a href="#cb13-6" aria-hidden="true" tabindex="-1"></a> <span class="pp">tokio::</span>spawn(<span class="kw">async</span> <span class="kw">move</span> <span class="op">{</span></span>
<span id="cb13-7"><a href="#cb13-7" aria-hidden="true" tabindex="-1"></a> <span class="cf">if</span> <span class="kw">let</span> <span class="cn">Err</span>(e) <span class="op">=</span> handle_query(buffer<span class="op">,</span> src_addr<span class="op">,</span> <span class="op">&amp;</span>ctx)<span class="op">.</span><span class="kw">await</span> <span class="op">{</span></span>
<span id="cb13-8"><a href="#cb13-8" aria-hidden="true" tabindex="-1"></a> <span class="pp">error!</span>(<span class="st">&quot;{} | HANDLER ERROR | {}&quot;</span><span class="op">,</span> src_addr<span class="op">,</span> e)<span class="op">;</span></span>
<span id="cb13-9"><a href="#cb13-9" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span></span>
<span id="cb13-10"><a href="#cb13-10" aria-hidden="true" tabindex="-1"></a> <span class="op">}</span>)<span class="op">;</span></span>
<span id="cb13-11"><a href="#cb13-11" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<p>Each <code>handle_query</code> walks a pipeline. This is the part
where “from scratch” pays off — every step is just a function that
either returns a response or says “not my problem, pass it on”:</p>
<pre><code> ┌─────────────────────────────────────────────────────┐
│ Numa Resolution Pipeline │
└─────────────────────────────────────────────────────┘
Query ──→ Overrides ──→ .numa TLD ──→ Blocklist ──→ Zones ──→ Cache ──→ DoH
│ │ │ │ │ │ │
│ │ match? │ match? │ blocked? │ match? │ hit? │
│ ↓ ↓ ↓ ↓ ↓ ↓
│ respond respond 0.0.0.0 respond respond forward
│ (auto-reverts (reverse (ad gone) (static (TTL to upstream
│ after N min) proxy+TLS) records) adjusted) (encrypted)
│
└──→ Each step either answers or passes to the next.
Adding a feature = inserting a function into this chain.</code></pre>
<p>Want conditional forwarding for Tailscale? Insert a step before the
upstream that checks the domain suffix. Want to override
<code>api.example.com</code> for 5 minutes while debugging? Insert an
entry in the overrides step — it auto-expires and the domain goes back
to resolving normally. A DNS library would have hidden this pipeline
behind an opaque <code>resolve()</code> call.</p>
<p>This is one of those cases where Rust + tokio makes things almost
embarrassingly simple. In a synchronous resolver, you’d need a thread
pool or hand-rolled event loop. Here, each query is a lightweight
future. A slow upstream query doesn’t block anything — other queries
keep flowing.</p>
<h2 id="dns-over-https-the-wait-thats-it-moment">DNS-over-HTTPS: the
“wait, that’s it?” moment</h2>
<p>The most recent addition, and honestly the one that surprised me with
how little code it needed. DoH (RFC 8484) is conceptually simple: take
the exact same DNS wire-format packet you’d send over UDP, POST it to an
HTTPS endpoint with <code>Content-Type: application/dns-message</code>,
and parse the response the same way. Same bytes, different
transport.</p>
<div class="sourceCode" id="cb15"><pre
class="sourceCode rust"><code class="sourceCode rust"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="kw">async</span> <span class="kw">fn</span> forward_doh(</span>
<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a> query<span class="op">:</span> <span class="op">&amp;</span>DnsPacket<span class="op">,</span></span>
<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a> url<span class="op">:</span> <span class="op">&amp;</span><span class="dt">str</span><span class="op">,</span></span>
<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a> client<span class="op">:</span> <span class="op">&amp;</span><span class="pp">reqwest::</span>Client<span class="op">,</span></span>
<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a> timeout_duration<span class="op">:</span> Duration<span class="op">,</span></span>
<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a>) <span class="op">-&gt;</span> <span class="dt">Result</span><span class="op">&lt;</span>DnsPacket<span class="op">&gt;</span> <span class="op">{</span></span>
<span id="cb15-7"><a href="#cb15-7" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> <span class="kw">mut</span> send_buffer <span class="op">=</span> <span class="pp">BytePacketBuffer::</span>new()<span class="op">;</span></span>
<span id="cb15-8"><a href="#cb15-8" aria-hidden="true" tabindex="-1"></a> query<span class="op">.</span>write(<span class="op">&amp;</span><span class="kw">mut</span> send_buffer)<span class="op">?;</span></span>
<span id="cb15-9"><a href="#cb15-9" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb15-10"><a href="#cb15-10" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> resp <span class="op">=</span> timeout(timeout_duration<span class="op">,</span> client</span>
<span id="cb15-11"><a href="#cb15-11" aria-hidden="true" tabindex="-1"></a> <span class="op">.</span>post(url)</span>
<span id="cb15-12"><a href="#cb15-12" aria-hidden="true" tabindex="-1"></a> <span class="op">.</span>header(<span class="st">&quot;content-type&quot;</span><span class="op">,</span> <span class="st">&quot;application/dns-message&quot;</span>)</span>
<span id="cb15-13"><a href="#cb15-13" aria-hidden="true" tabindex="-1"></a> <span class="op">.</span>header(<span class="st">&quot;accept&quot;</span><span class="op">,</span> <span class="st">&quot;application/dns-message&quot;</span>)</span>
<span id="cb15-14"><a href="#cb15-14" aria-hidden="true" tabindex="-1"></a> <span class="op">.</span>body(send_buffer<span class="op">.</span>filled()<span class="op">.</span>to_vec())</span>
<span id="cb15-15"><a href="#cb15-15" aria-hidden="true" tabindex="-1"></a> <span class="op">.</span>send())</span>
<span id="cb15-16"><a href="#cb15-16" aria-hidden="true" tabindex="-1"></a> <span class="op">.</span><span class="kw">await</span><span class="op">??.</span>error_for_status()<span class="op">?;</span></span>
<span id="cb15-17"><a href="#cb15-17" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb15-18"><a href="#cb15-18" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> bytes <span class="op">=</span> resp<span class="op">.</span>bytes()<span class="op">.</span><span class="kw">await</span><span class="op">?;</span></span>
<span id="cb15-19"><a href="#cb15-19" aria-hidden="true" tabindex="-1"></a> <span class="kw">let</span> <span class="kw">mut</span> recv_buffer <span class="op">=</span> <span class="pp">BytePacketBuffer::</span>from_bytes(<span class="op">&amp;</span>bytes)<span class="op">;</span></span>
<span id="cb15-20"><a href="#cb15-20" aria-hidden="true" tabindex="-1"></a> <span class="pp">DnsPacket::</span>from_buffer(<span class="op">&amp;</span><span class="kw">mut</span> recv_buffer)</span>
<span id="cb15-21"><a href="#cb15-21" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<p>The one gotcha that cost me an hour: Quad9 and other DoH providers
require HTTP/2. My first attempt used HTTP/1.1 and got a cryptic 400 Bad
Request. Adding the <code>http2</code> feature to reqwest fixed it. The
upside of HTTP/2? Connection multiplexing means subsequent queries reuse
the TLS session — ~16ms vs ~50ms for the first query. Free
performance.</p>
<p>The <code>Upstream</code> enum dispatches between UDP and DoH based
on the URL scheme:</p>
<div class="sourceCode" id="cb16"><pre
class="sourceCode rust"><code class="sourceCode rust"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="kw">pub</span> <span class="kw">enum</span> Upstream <span class="op">{</span></span>
<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a> Udp(SocketAddr)<span class="op">,</span></span>
<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a> Doh <span class="op">{</span> url<span class="op">:</span> <span class="dt">String</span><span class="op">,</span> client<span class="op">:</span> <span class="pp">reqwest::</span>Client <span class="op">},</span></span>
<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<p>If the configured address starts with <code>https://</code>, it’s
DoH. Otherwise, plain UDP. Simple, no toggles.</p>
<h2 id="why-not-just-use-dnsmasq-nginx-mkcert">“Why not just use dnsmasq
+ nginx + mkcert?”</h2>
<p>Fair question — I got this a lot when I first <a
href="https://www.reddit.com/r/programare/">posted about Numa</a>. And
the answer is: you absolutely can. Those are mature, battle-tested
tools.</p>
<p>The difference is integration. With dnsmasq + nginx + mkcert, you’re
configuring three tools: DNS resolution, reverse proxy rules, and
certificate generation. Each has its own config format, its own
lifecycle, its own failure modes. Numa puts the DNS record, the reverse
proxy, and the TLS cert behind a single API call:</p>
<div class="sourceCode" id="cb17"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="ex">curl</span> <span class="at">-X</span> POST localhost:5380/services <span class="at">-d</span> <span class="st">&#39;{&quot;name&quot;:&quot;frontend&quot;,&quot;target_port&quot;:5173}&#39;</span></span></code></pre></div>
<p>That creates the DNS entry, generates a TLS certificate with the
correct SAN, and starts proxying — including WebSocket upgrade for Vite
HMR. One command, no config files.</p>
<p>There’s also a distinction people miss: <strong>mkcert and certbot
solve different problems.</strong> Certbot issues certificates for
public domains via Let’s Encrypt — it needs DNS validation or an open
port 80. Numa generates certificates for <code>.numa</code> domains that
don’t exist publicly. You can’t get a Let’s Encrypt cert for
<code>frontend.numa</code>. They’re complementary, not alternatives.</p>
<p>Someone on Reddit told me the real value is “TLS termination +
reverse proxy, simple to install, for developers — stop there.”
Honestly, they might be right about focus. But DNS is the foundation the
proxy sits on, and having full control over the resolution pipeline is
what makes auto-revert overrides and LAN discovery possible. Sometimes
the “unnecessary” part is what makes the interesting part work.</p>
<h2 id="the-blocklist-memory-problem">The blocklist memory problem</h2>
<p>Numa’s ad blocking loads the <a
href="https://github.com/hagezi/dns-blocklists">Hagezi Pro</a> list at
startup — ~385,000 domains stored in a
<code>HashSet&lt;String&gt;</code>. This works, but it consumes ~30MB of
memory. For a laptop DNS proxy, that’s fine. For embedded devices or a
future where you want to run Numa on a router, it’s too much.</p>
<p>The obvious optimization is a <strong>Bloom filter</strong> — a
probabilistic data structure that can tell you “definitely not in the
set” or “probably in the set” using a fraction of the memory. A Bloom
filter for 385K domains with a 0.1% false positive rate would use ~700KB
instead of 30MB. The false positives (0.1% of queries hitting domains
not in the list) would be blocked unnecessarily, which is acceptable for
ad blocking.</p>
<p>I haven’t implemented this yet — the <code>HashSet</code> is simple,
correct, and 30MB is nothing on a laptop. But if Numa ever needs to run
on a router or a Raspberry Pi, this is the first optimization I’d reach
for.</p>
<h2 id="what-i-learned">What I learned</h2>
<p><strong>DNS is a 40-year-old protocol that works remarkably
well.</strong> The wire format is tight, the caching model is elegant,
and the hierarchical delegation system has scaled to billions of queries
per day. The things people complain about (DNSSEC complexity, lack of
encryption) are extensions bolted on decades later, not flaws in the
original design.</p>
<p><strong>“From scratch” gives you full control.</strong> When I wanted
to add ephemeral overrides that auto-revert, it was trivial — just a new
step in the resolution pipeline. Conditional forwarding for
Tailscale/VPN? Another step. Every feature is a function that takes a
query and returns either a response or “pass to the next stage.” A DNS
library would have hidden this pipeline.</p>
<p><strong>The hard parts aren’t where you’d expect.</strong> Parsing
the wire protocol was straightforward (RFC 1035 is well-written). The
hard parts were: browsers rejecting wildcard certs under single-label
TLDs (<code>*.numa</code> fails — you need per-service SANs), macOS
resolver quirks (scutil vs /etc/resolv.conf), and getting multiple
processes to bind the same multicast port (<code>SO_REUSEPORT</code> on
macOS, <code>SO_REUSEADDR</code> on Linux).</p>
<p><strong>Terminology will get you roasted.</strong> I initially called
Numa a “DNS resolver” and got corrected on Reddit — it’s a forwarding
resolver (DNS proxy). It doesn’t walk the delegation chain from root
servers; it forwards to an upstream. The distinction matters to people
who work with DNS for a living, and being sloppy about it cost me
credibility in my first community posts. If you’re building in a domain
with established terminology, learn the vocabulary before you show
up.</p>
<h2 id="whats-next">What’s next</h2>
<p>Numa is at v0.5.0 with DNS forwarding, caching, ad blocking,
DNS-over-HTTPS, .numa local domains with auto TLS, and LAN service
discovery.</p>
<p>On the roadmap:</p>
<ul>
<li><strong>DoT (DNS-over-TLS)</strong> — DoH was first because it
passes through captive portals and corporate firewalls (port 443 vs
853). DoT has less framing overhead, so it’s faster. Both will be
available.</li>
<li><strong>Recursive resolution</strong> — walk the delegation chain
from root servers instead of forwarding. Combined with DNSSEC
validation, this removes the need to trust any upstream resolver.</li>
<li><strong><a href="https://github.com/pubky/pkarr">pkarr</a>
integration</strong> — self-sovereign DNS via the Mainline BitTorrent
DHT. Publish DNS records signed with your Ed25519 key, no registrar
needed.</li>
</ul>
<p>But those are rabbit holes for future posts.</p>
<p><a
href="https://github.com/razvandimescu/numa">github.com/razvandimescu/numa</a></p>
</article>
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<title>Blog — Numa</title>
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<body>
<nav class="blog-nav">
<a href="/" class="wordmark">Numa</a>
<span class="sep">/</span>
<a href="/blog/">Blog</a>
</nav>
<main class="blog-index">
<h1>Blog</h1>
<ul class="post-list">
<li>
<a href="/blog/dns-from-scratch.html">
<div class="post-title">I Built a DNS Resolver from Scratch in Rust</div>
<div class="post-desc">How DNS actually works at the wire level — label compression, TTL tricks, DoH implementation, and what I learned building a resolver with zero DNS libraries.</div>
<div class="post-date">March 2026</div>
</a>
</li>
</ul>
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<meta charset="UTF-8"> <meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Numa — DNS that governs itself</title> <title>Numa — DNS you own. Everywhere you go.</title>
<meta name="description" content="DNS you own. Block ads, override DNS for development, name your local services with .numa domains, cache for speed. A single portable binary built from scratch in Rust."> <meta name="description" content="DNS you own. Block ads, override DNS for development, name your local services with .numa domains, cache for speed. A single portable binary built from scratch in Rust.">
<link rel="canonical" href="https://numa.rs">
<meta property="og:title" content="Numa — DNS you own. Everywhere you go.">
<meta property="og:description" content="Portable DNS resolver with ad blocking, encrypted upstream, .numa local domains, and developer overrides. Built from scratch in Rust.">
<meta property="og:type" content="website">
<meta property="og:url" content="https://numa.rs">
<link rel="preconnect" href="https://fonts.googleapis.com"> <link rel="preconnect" href="https://fonts.googleapis.com">
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@@ -785,6 +790,169 @@ p.lead {
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} }
/* ===========================
PERFORMANCE
=========================== */
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/* =========================== /* ===========================
TECHNICAL TECHNICAL
=========================== */ =========================== */
@@ -824,6 +992,8 @@ p.lead {
color: var(--text-secondary); color: var(--text-secondary);
overflow-x: auto; overflow-x: auto;
position: relative; position: relative;
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@@ -980,6 +1150,7 @@ footer .closing {
.problem-grid { grid-template-columns: 1fr; gap: 2rem; } .problem-grid { grid-template-columns: 1fr; gap: 2rem; }
.layers-grid { grid-template-columns: 1fr; } .layers-grid { grid-template-columns: 1fr; }
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.hero-line { display: none; } .hero-line { display: none; }
@@ -1036,9 +1207,9 @@ footer .closing {
</div> </div>
<div class="problem-grid"> <div class="problem-grid">
<div class="problem-text reveal reveal-delay-1"> <div class="problem-text reveal reveal-delay-1">
<p>Every time you visit a website, you ask a DNS resolver where to go. That resolver sees every domain you visit, when, and how often.</p> <p>Every time you visit a website, you ask a DNS resolver where to go. That resolver sees every domain you visit, when, and how often. Your ISP logs these queries by default.</p>
<p>Today, a handful of operators control this infrastructure. ICANN governs the root. Registrars can seize domains. Governments compel censorship. Your ISP logs your queries by default.</p> <p>Ad blockers work in one browser. Pi-hole needs a Raspberry Pi. Your local dev services live at <code>localhost:5173</code> and you can never remember which port is which.</p>
<p>The protocol that underpins the entire internet has no built-in privacy, no cryptographic ownership, and no way for users to choose who they trust.</p> <p>DNS is the foundation of everything you do on the internet, but the tools for controlling it locally are either too complex (dnsmasq + nginx + mkcert) or too limited (cloud-only, appliance-only).</p>
</div> </div>
<div class="dns-diagram reveal reveal-delay-2"> <div class="dns-diagram reveal reveal-delay-2">
<div class="dns-node"><span class="node-dot dim"></span>Your browser</div> <div class="dns-node"><span class="node-dot dim"></span>Your browser</div>
@@ -1062,44 +1233,43 @@ footer .closing {
<div class="container"> <div class="container">
<div class="reveal"> <div class="reveal">
<div class="section-label">How It Works</div> <div class="section-label">How It Works</div>
<h2>Three layers, built incrementally</h2> <h2>What it does today</h2>
<p class="lead">Numa starts as a practical developer tool and evolves toward a decentralized network. Each layer stands on its own.</p> <p class="lead">A portable DNS proxy with ad blocking, encrypted upstream, local service domains, and a REST API. Everything runs in a single binary.</p>
</div> </div>
<div class="layers-grid"> <div class="layers-grid">
<div class="layer-card reveal reveal-delay-1"> <div class="layer-card reveal reveal-delay-1">
<div class="layer-badge">Today</div> <div class="layer-badge">Layer 1</div>
<h3>DNS You Control</h3> <h3>Block &amp; Protect</h3>
<ul> <ul>
<li>Ad &amp; tracker blocking &mdash; 385K+ domains, zero config</li> <li>Ad &amp; tracker blocking &mdash; 385K+ domains, zero config</li>
<li>Ephemeral DNS overrides with auto-revert</li> <li>DNS-over-HTTPS &mdash; encrypted upstream (Quad9, Cloudflare, any provider)</li>
<li>Local service proxy &mdash; <code>frontend.numa</code> instead of <code>localhost:5173</code></li>
<li>Live dashboard with real-time stats and controls</li>
<li>REST API &mdash; 22 endpoints for programmatic control</li>
<li>TTL-aware caching (sub-ms lookups)</li> <li>TTL-aware caching (sub-ms lookups)</li>
<li>Single binary, portable &mdash; your ad blocker travels with you</li> <li>Single binary, portable &mdash; your DNS travels with you</li>
<li>macOS, Linux, and Windows</li>
</ul> </ul>
</div> </div>
<div class="layer-card reveal reveal-delay-2"> <div class="layer-card reveal reveal-delay-2">
<div class="layer-badge">Next</div> <div class="layer-badge">Layer 2</div>
<h3>Self-Sovereign DNS</h3> <h3>Developer Tools</h3>
<ul> <ul>
<li>pkarr integration: Ed25519 keys as domains</li> <li>Local service proxy &mdash; <code>frontend.numa</code> instead of <code>localhost:5173</code></li>
<li>Resolve via Mainline BitTorrent DHT (10M+ nodes)</li> <li>Path-based routing &mdash; <code>app.numa/api</code> &rarr; <code>:5001</code></li>
<li>No registrar, no blockchain, no ICANN</li> <li>Ephemeral DNS overrides with auto-revert</li>
<li>Cryptographic verification built-in</li> <li>LAN service discovery via mDNS</li>
<li>Human-readable aliases for pkarr domains</li> <li>Conditional forwarding &mdash; plays nice with Tailscale/VPN split-DNS</li>
<li>REST API &mdash; script everything, automate anything</li>
<li>Live dashboard with real-time stats and controls</li>
</ul> </ul>
</div> </div>
<div class="layer-card reveal reveal-delay-3"> <div class="layer-card reveal reveal-delay-3">
<div class="layer-badge">Vision</div> <div class="layer-badge">Coming Next</div>
<h3>Decentralized Resolver Network</h3> <h3>Self-Sovereign DNS</h3>
<ul> <ul>
<li>Operators run Numa nodes and stake tokens</li> <li>pkarr integration &mdash; DNS via Mainline DHT, no registrar needed</li>
<li>Earn rewards for uptime, correctness, latency</li> <li>Global <code>.numa</code> names &mdash; self-publish, DHT-backed</li>
<li>Independent auditors send challenge queries</li> <li>.onion bridge &mdash; human-readable names for Tor hidden services</li>
<li>Slashing for NXDOMAIN hijacking or poisoned records</li> <li>Ed25519 same-key binding &mdash; zero new trust assumptions</li>
<li>Geographic diversity bonuses</li> <li>No blockchain required for core naming</li>
<li>Privacy-preserving resolution (DoH/DoT)</li>
</ul> </ul>
</div> </div>
</div> </div>
@@ -1131,66 +1301,12 @@ footer .closing {
<span class="pipeline-arrow">&rarr;</span> <span class="pipeline-arrow">&rarr;</span>
<div class="pipeline-node"><div class="pipeline-box">Cache</div></div> <div class="pipeline-node"><div class="pipeline-box">Cache</div></div>
<span class="pipeline-arrow">&rarr;</span> <span class="pipeline-arrow">&rarr;</span>
<div class="pipeline-node"><div class="pipeline-box hl-violet">pkarr / DHT</div></div> <div class="pipeline-node"><div class="pipeline-box hl-violet">DoH Upstream</div></div>
<span class="pipeline-arrow">&rarr;</span>
<div class="pipeline-node"><div class="pipeline-box">Upstream</div></div>
<span class="pipeline-arrow">&rarr;</span> <span class="pipeline-arrow">&rarr;</span>
<div class="pipeline-node"><div class="pipeline-box hl-emerald">Respond</div></div> <div class="pipeline-node"><div class="pipeline-box hl-emerald">Respond</div></div>
</div> </div>
</div> </div>
<div class="arch-subsection reveal">
<h3>Layered resilience</h3>
<div class="layer-stack">
<div class="stack-row">
<div class="stack-label" style="color: var(--violet)">L4 Permanence</div>
<div class="stack-value">Arweave immutable zone snapshots (future)</div>
</div>
<div class="stack-row">
<div class="stack-label" style="color: var(--violet-dim)">L3 Distribution</div>
<div class="stack-value">Mainline DHT via pkarr &mdash; 10M+ nodes</div>
</div>
<div class="stack-row">
<div class="stack-label" style="color: var(--amber)">L2 Serving</div>
<div class="stack-value">Numa instances worldwide</div>
</div>
<div class="stack-row">
<div class="stack-label" style="color: var(--teal)">L1 Compatibility</div>
<div class="stack-value">Standard DNS wire protocol &mdash; RFC 1035</div>
</div>
</div>
</div>
<div class="arch-subsection reveal">
<h3>Network actors</h3>
<div class="network-grid">
<div class="network-actor">
<span class="actor-icon" style="color: var(--teal)" aria-hidden="true">&compfn;</span>
<h4 style="color: var(--teal)">Users</h4>
<p>Choose resolvers from a decentralized marketplace based on latency, privacy, and reputation</p>
</div>
<div class="network-actor">
<span class="actor-icon" style="color: var(--amber)" aria-hidden="true">&diamond;</span>
<h4 style="color: var(--amber)">Operators</h4>
<p>Stake tokens, run Numa nodes, earn rewards proportional to verified service quality</p>
</div>
<div class="network-actor">
<span class="actor-icon" style="color: var(--rose)" aria-hidden="true">&target;</span>
<h4 style="color: var(--rose)">Auditors</h4>
<p>Send challenge queries from diverse locations, verify correctness and latency</p>
</div>
<div class="network-actor">
<span class="actor-icon" style="color: var(--violet)" aria-hidden="true">&equiv;</span>
<h4 style="color: var(--violet)">Chain</h4>
<p>Accounting, reputation scores, reward distribution, slashing proofs</p>
</div>
</div>
<div class="network-connections" aria-hidden="true">
<div class="network-conn-line"></div>
<div class="network-conn-line"></div>
<div class="network-conn-line"></div>
</div>
</div>
</div> </div>
</section> </section>
@@ -1265,6 +1381,22 @@ footer .closing {
<td class="check">Yes</td> <td class="check">Yes</td>
<td class="check">Real-time + controls</td> <td class="check">Real-time + controls</td>
</tr> </tr>
<tr>
<td>DNS-over-HTTPS upstream</td>
<td class="cross">No</td>
<td class="check">Yes</td>
<td class="check">Yes</td>
<td class="cross">No</td>
<td class="check">Built in (HTTP/2 + rustls)</td>
</tr>
<tr>
<td>Conditional forwarding</td>
<td class="cross">No</td>
<td class="cross">No</td>
<td class="cross">No</td>
<td class="muted">Manual</td>
<td class="check">Auto-detects Tailscale/VPN</td>
</tr>
<tr> <tr>
<td>Zero config needed</td> <td>Zero config needed</td>
<td class="cross">Complex setup</td> <td class="cross">Complex setup</td>
@@ -1273,14 +1405,6 @@ footer .closing {
<td class="cross">Docker/setup</td> <td class="cross">Docker/setup</td>
<td class="check">Works out of the box</td> <td class="check">Works out of the box</td>
</tr> </tr>
<tr>
<td>Self-sovereign DNS roadmap</td>
<td class="cross">No</td>
<td class="cross">No</td>
<td class="cross">No</td>
<td class="cross">No</td>
<td class="check">pkarr / DHT</td>
</tr>
</tbody> </tbody>
</table> </table>
</div> </div>
@@ -1289,6 +1413,125 @@ footer .closing {
<div class="section-road" aria-hidden="true"><div class="roman-bricks"></div></div> <div class="section-road" aria-hidden="true"><div class="roman-bricks"></div></div>
<!-- ==================== PERFORMANCE ==================== -->
<section class="perf-section" id="performance">
<div class="container">
<div class="reveal">
<div class="section-label" style="color: var(--emerald)">Performance</div>
<h2>Measured, not claimed</h2>
<p class="lead">Benchmarked with <code style="font-size:0.85em">dig</code> against public resolvers on the same machine. Cached queries resolve in under a microsecond.</p>
</div>
<div class="perf-grid">
<div class="reveal reveal-delay-1">
<div class="perf-table-wrapper">
<table class="perf-table">
<caption class="sr-only">DNS resolver latency comparison</caption>
<thead>
<tr>
<th>Resolver</th>
<th>Avg</th>
<th>P50</th>
<th>P99</th>
</tr>
</thead>
<tbody>
<tr class="perf-highlight">
<td>Numa (cached)</td>
<td>&lt;1ms</td>
<td>&lt;1ms</td>
<td>&lt;1ms</td>
</tr>
<tr>
<td>Numa (cold)</td>
<td>9ms</td>
<td>9ms</td>
<td>18ms</td>
</tr>
<tr>
<td>System resolver</td>
<td>9ms</td>
<td>8ms</td>
<td>44ms</td>
</tr>
<tr>
<td>Quad9</td>
<td>15ms</td>
<td>13ms</td>
<td>43ms</td>
</tr>
<tr>
<td>Cloudflare</td>
<td>19ms</td>
<td>14ms</td>
<td>132ms</td>
</tr>
<tr>
<td>Google</td>
<td>22ms</td>
<td>17ms</td>
<td>37ms</td>
</tr>
</tbody>
</table>
</div>
<div class="perf-bar-group">
<div class="perf-bar-row">
<span class="perf-bar-label">Numa</span>
<div class="perf-bar-track"><div class="perf-bar-fill emerald" style="width: 2%"></div></div>
<span class="perf-bar-ms">&lt;1ms</span>
</div>
<div class="perf-bar-row">
<span class="perf-bar-label">System</span>
<div class="perf-bar-track"><div class="perf-bar-fill dim" style="width: 20%"></div></div>
<span class="perf-bar-ms">9ms</span>
</div>
<div class="perf-bar-row">
<span class="perf-bar-label">Quad9</span>
<div class="perf-bar-track"><div class="perf-bar-fill dim" style="width: 33%"></div></div>
<span class="perf-bar-ms">15ms</span>
</div>
<div class="perf-bar-row">
<span class="perf-bar-label">Cloudflare</span>
<div class="perf-bar-track"><div class="perf-bar-fill dim" style="width: 42%"></div></div>
<span class="perf-bar-ms">19ms</span>
</div>
<div class="perf-bar-row">
<span class="perf-bar-label">Google</span>
<div class="perf-bar-track"><div class="perf-bar-fill dim" style="width: 49%"></div></div>
<span class="perf-bar-ms">22ms</span>
</div>
</div>
</div>
<div class="perf-sidebar reveal reveal-delay-2">
<div class="perf-stat">
<div class="perf-stat-value emerald">689 ns</div>
<div class="perf-stat-label">Cached round-trip &mdash; parse query, cache lookup, serialize response</div>
</div>
<div class="perf-stat">
<div class="perf-stat-value teal">2.0M</div>
<div class="perf-stat-label">Queries per second (single-threaded pipeline throughput, batched)</div>
</div>
<div class="perf-stat">
<div class="perf-stat-value amber">0 allocations</div>
<div class="perf-stat-label">Heap allocations in the I/O path &mdash; 4KB stack buffers, inline serialization</div>
</div>
<p class="perf-note">
Cold queries match system resolver speed &mdash; the bottleneck is upstream RTT, not Numa. We don't claim to be faster when the network is the limit.
<br><br>
Benchmarks are reproducible: <code style="font-size:0.85em">cargo bench</code> for micro-benchmarks, <code style="font-size:0.85em">python3 bench/dns-bench.sh</code> for end-to-end.
<a href="https://github.com/razvandimescu/numa/tree/main/bench">Methodology &rarr;</a>
</p>
</div>
</div>
</div>
</section>
<div class="section-road on-surface" aria-hidden="true"><div class="roman-bricks"></div></div>
<!-- ==================== TECHNICAL ==================== --> <!-- ==================== TECHNICAL ==================== -->
<section id="technical"> <section id="technical">
<div class="container"> <div class="container">
@@ -1305,25 +1548,30 @@ footer .closing {
<dd>Zero &mdash; wire protocol parsed from scratch</dd> <dd>Zero &mdash; wire protocol parsed from scratch</dd>
<dt>Dependencies</dt> <dt>Dependencies</dt>
<dd>8 runtime crates (tokio, axum, hyper, serde, serde_json, toml, log, futures)</dd> <dd>18 runtime crates &mdash; tokio, axum, hyper, reqwest (DoH), rcgen + rustls (TLS), socket2 (multicast), serde, and more</dd>
<dt>Packet Format</dt> <dt>Packet Format</dt>
<dd>RFC 1035 compliant, 4096-byte UDP (EDNS)</dd> <dd>RFC 1035 compliant, 4096-byte UDP (EDNS)</dd>
<dt>Concurrency</dt> <dt>Concurrency</dt>
<dd>Arc&lt;ServerCtx&gt; + std::sync::Mutex (sub-&micro;s holds, never across .await)</dd> <dd>Arc&lt;ServerCtx&gt; + RwLock for reads, Mutex for writes (never across .await)</dd>
<dt>Signatures</dt> <dt>Upstream</dt>
<dd>Ed25519 via pkarr for self-sovereign domains</dd> <dd>DNS-over-HTTPS (DoH) via reqwest + http2 + rustls</dd>
</dl> </dl>
<div class="code-block reveal reveal-delay-2"> <div class="code-block reveal reveal-delay-2">
<span class="comment"># Install (pick one)</span>
<span class="prompt">$</span> <span class="cmd">brew install</span> razvandimescu/tap/numa
<span class="prompt">$</span> <span class="cmd">cargo install</span> numa <span class="prompt">$</span> <span class="cmd">cargo install</span> numa
<span class="prompt">$</span> <span class="cmd">curl</span> <span class="flag">-fsSL</span> https://raw.githubusercontent.com/razvandimescu/numa/main/install.sh <span class="flag">|</span> <span class="cmd">sh</span>
<span class="comment"># Run</span>
<span class="prompt">$</span> <span class="cmd">sudo numa</span> <span class="comment"># bind to :53, :80, :5380</span> <span class="prompt">$</span> <span class="cmd">sudo numa</span> <span class="comment"># bind to :53, :80, :5380</span>
<span class="prompt">$</span> <span class="cmd">dig</span> <span class="flag">@127.0.0.1</span> google.com <span class="comment"># test resolution</span> <span class="prompt">$</span> <span class="cmd">dig</span> <span class="flag">@127.0.0.1</span> google.com <span class="comment"># test resolution</span>
<span class="prompt">$</span> <span class="cmd">open</span> http://numa.numa <span class="comment"># dashboard</span> <span class="prompt">$</span> <span class="cmd">open</span> http://localhost:5380 <span class="comment"># dashboard</span>
<span class="prompt">$</span> <span class="cmd">curl</span> <span class="flag">-X POST</span> localhost:5380/services \ <span class="prompt">$</span> <span class="cmd">curl</span> <span class="flag">-X POST</span> localhost:5380/services \
<span class="flag">-d</span> <span class="str">'{"name":"frontend", <span class="flag">-d</span> <span class="str">'{"name":"frontend",
"target_port":5173}'</span> <span class="comment"># http://frontend.numa</span> "target_port":5173}'</span> <span class="comment"># https://frontend.numa</span>
</div> </div>
</div> </div>
</div> </div>
@@ -1345,7 +1593,7 @@ footer .closing {
</div> </div>
<div class="roadmap-item done"> <div class="roadmap-item done">
<span class="phase">Phase 1</span> <span class="phase">Phase 1</span>
<span class="phase-desc">Override layer + REST API with 18 endpoints</span> <span class="phase-desc">Override layer + REST API for programmatic DNS control</span>
</div> </div>
<div class="roadmap-item done"> <div class="roadmap-item done">
<span class="phase">Phase 2</span> <span class="phase">Phase 2</span>
@@ -1359,25 +1607,21 @@ footer .closing {
<span class="phase">Phase 4</span> <span class="phase">Phase 4</span>
<span class="phase-desc">Local service proxy &mdash; .numa domains, HTTP/HTTPS reverse proxy, auto TLS, WebSocket</span> <span class="phase-desc">Local service proxy &mdash; .numa domains, HTTP/HTTPS reverse proxy, auto TLS, WebSocket</span>
</div> </div>
<div class="roadmap-item phase-teal"> <div class="roadmap-item done">
<span class="phase">Phase 5</span> <span class="phase">Phase 5</span>
<span class="phase-desc">pkarr integration &mdash; resolve Ed25519 keys via Mainline DHT (15M nodes)</span> <span class="phase-desc">DNS-over-HTTPS &mdash; encrypted upstream, HTTP/2 connection pooling</span>
</div> </div>
<div class="roadmap-item phase-teal"> <div class="roadmap-item phase-teal">
<span class="phase">Phase 6</span> <span class="phase">Phase 6</span>
<span class="phase-desc">pkarr integration &mdash; self-sovereign DNS via Mainline DHT, no registrar needed</span>
</div>
<div class="roadmap-item phase-teal">
<span class="phase">Phase 7</span>
<span class="phase-desc">Global .numa names &mdash; self-publish, DHT-backed, first-come-first-served</span> <span class="phase-desc">Global .numa names &mdash; self-publish, DHT-backed, first-come-first-served</span>
</div> </div>
<div class="roadmap-item phase-amber"> <div class="roadmap-item phase-teal">
<span class="phase">Phase 7</span>
<span class="phase-desc">Audit protocol &mdash; challenge-based verification of resolver honesty</span>
</div>
<div class="roadmap-item phase-violet">
<span class="phase">Phase 8</span> <span class="phase">Phase 8</span>
<span class="phase-desc">Numa Network &mdash; proof-of-service consensus, NUMA token, paid .numa domains</span> <span class="phase-desc">.onion bridge &mdash; human-readable Tor naming via Ed25519 same-key binding</span>
</div>
<div class="roadmap-item phase-violet">
<span class="phase">Phase 9</span>
<span class="phase-desc">.onion bridge &mdash; human-readable .numa names for Tor hidden services</span>
</div> </div>
</div> </div>
</div> </div>
@@ -1391,6 +1635,7 @@ footer .closing {
</p> </p>
<div class="footer-links reveal reveal-delay-1"> <div class="footer-links reveal reveal-delay-1">
<a href="https://github.com/razvandimescu/numa" target="_blank" rel="noopener">GitHub</a> <a href="https://github.com/razvandimescu/numa" target="_blank" rel="noopener">GitHub</a>
<a href="/blog/">Blog</a>
<a href="https://github.com/razvandimescu/numa/blob/main/LICENSE" target="_blank" rel="noopener">MIT License</a> <a href="https://github.com/razvandimescu/numa/blob/main/LICENSE" target="_blank" rel="noopener">MIT License</a>
</div> </div>
<p class="closing reveal reveal-delay-2">Built from scratch in Rust. No dependencies on trust.</p> <p class="closing reveal reveal-delay-2">Built from scratch in Rust. No dependencies on trust.</p>