feat: DoH server endpoint + DoT enabled by default (#79)

* chore: document multi-forwarder and cache warming in config and README

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: DNS-over-HTTPS server endpoint (RFC 8484)

Serve DoH at POST /dns-query on the existing HTTPS proxy (port 443).
Automatically enabled when proxy TLS is active — no config needed.
Also fix zone map priority so local zones override RFC 6762 .local
special-use handling.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* style: cargo fmt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: remove GoatCounter analytics from site

GoatCounter domains (goatcounter.com, gc.zgo.at) are blocked by
Hagezi Pro, which is Numa's default blocklist. A DNS privacy tool
should not embed analytics that its own resolver blocks.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: enable DoT listener by default

DoT now starts automatically with `sudo numa`, matching the proxy and
DoH which are already on by default. The self-signed CA infrastructure
is shared with the proxy, so there is no additional setup. This makes
`numa setup-phone` work out of the box.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/doh.rs

@@ -0,0 +1,188 @@
+use std::net::SocketAddr;
+
+use axum::body::Bytes;
+use axum::extract::{Request, State};
+use axum::response::{IntoResponse, Response};
+use hyper::StatusCode;
+use log::warn;
+
+use crate::buffer::BytePacketBuffer;
+use crate::ctx::{resolve_query, ServerCtx};
+use crate::header::ResultCode;
+use crate::packet::DnsPacket;
+
+const MAX_DNS_MSG: usize = 4096;
+const DOH_CONTENT_TYPE: &str = "application/dns-message";
+
+pub async fn doh_post(State(state): State<super::proxy::DohState>, req: Request) -> Response {
+    let host = super::proxy::extract_host(&req);
+    if !is_doh_host(host.as_deref(), &state.ctx.proxy_tld) {
+        return StatusCode::NOT_FOUND.into_response();
+    }
+
+    let content_type = req
+        .headers()
+        .get(hyper::header::CONTENT_TYPE)
+        .and_then(|v| v.to_str().ok())
+        .unwrap_or("");
+    if !content_type.starts_with(DOH_CONTENT_TYPE) {
+        return StatusCode::UNSUPPORTED_MEDIA_TYPE.into_response();
+    }
+
+    let body = match axum::body::to_bytes(req.into_body(), MAX_DNS_MSG).await {
+        Ok(b) => b,
+        Err(_) => {
+            return (StatusCode::PAYLOAD_TOO_LARGE, "body exceeds 4096 bytes").into_response()
+        }
+    };
+
+    if body.is_empty() {
+        return (StatusCode::BAD_REQUEST, "empty body").into_response();
+    }
+
+    let src = state
+        .remote_addr
+        .unwrap_or_else(|| SocketAddr::from(([127, 0, 0, 1], 0)));
+
+    resolve_doh(&body, src, &state.ctx).await
+}
+
+fn is_doh_host(host: Option<&str>, tld: &str) -> bool {
+    match host {
+        Some(h) if h == tld => true,
+        Some(h) => {
+            h.len() == 2 * tld.len() + 1
+                && h.starts_with(tld)
+                && h.as_bytes().get(tld.len()) == Some(&b'.')
+                && h.ends_with(tld)
+        }
+        None => false,
+    }
+}
+
+async fn resolve_doh(dns_bytes: &[u8], src: SocketAddr, ctx: &ServerCtx) -> Response {
+    let mut buffer = BytePacketBuffer::from_bytes(dns_bytes);
+    let query = match DnsPacket::from_buffer(&mut buffer) {
+        Ok(q) => q,
+        Err(e) => {
+            warn!("DoH: parse error from {}: {}", src, e);
+            let query_id = u16::from_be_bytes([
+                dns_bytes.first().copied().unwrap_or(0),
+                dns_bytes.get(1).copied().unwrap_or(0),
+            ]);
+            let mut resp = DnsPacket::new();
+            resp.header.id = query_id;
+            resp.header.response = true;
+            resp.header.rescode = ResultCode::FORMERR;
+            return serialize_response(&resp);
+        }
+    };
+
+    let query_id = query.header.id;
+    let query_rd = query.header.recursion_desired;
+    let questions = query.questions.clone();
+
+    match resolve_query(query, src, ctx).await {
+        Ok(resp_buffer) => {
+            let min_ttl = extract_min_ttl(resp_buffer.filled());
+            dns_response(resp_buffer.filled(), min_ttl)
+        }
+        Err(e) => {
+            warn!("DoH: resolve error for {}: {}", src, e);
+            let mut resp = DnsPacket::new();
+            resp.header.id = query_id;
+            resp.header.response = true;
+            resp.header.recursion_desired = query_rd;
+            resp.header.recursion_available = true;
+            resp.header.rescode = ResultCode::SERVFAIL;
+            resp.questions = questions;
+            serialize_response(&resp)
+        }
+    }
+}
+
+fn extract_min_ttl(wire: &[u8]) -> u32 {
+    let mut buf = BytePacketBuffer::from_bytes(wire);
+    match DnsPacket::from_buffer(&mut buf) {
+        Ok(pkt) => pkt.answers.iter().map(|r| r.ttl()).min().unwrap_or(0),
+        Err(_) => 0,
+    }
+}
+
+fn dns_response(wire: &[u8], min_ttl: u32) -> Response {
+    (
+        StatusCode::OK,
+        [
+            (hyper::header::CONTENT_TYPE, DOH_CONTENT_TYPE),
+            (
+                hyper::header::CACHE_CONTROL,
+                &format!("max-age={}", min_ttl),
+            ),
+        ],
+        Bytes::copy_from_slice(wire),
+    )
+        .into_response()
+}
+
+fn serialize_response(pkt: &DnsPacket) -> Response {
+    let mut buf = BytePacketBuffer::new();
+    match pkt.write(&mut buf) {
+        Ok(_) => dns_response(buf.filled(), 0),
+        Err(_) => StatusCode::INTERNAL_SERVER_ERROR.into_response(),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::buffer::BytePacketBuffer;
+    use crate::header::ResultCode;
+    use crate::packet::DnsPacket;
+    use crate::record::DnsRecord;
+
+    #[test]
+    fn is_doh_host_matches_tld() {
+        assert!(is_doh_host(Some("numa"), "numa"));
+        assert!(is_doh_host(Some("numa.numa"), "numa"));
+        assert!(!is_doh_host(Some("foo.numa"), "numa"));
+        assert!(!is_doh_host(None, "numa"));
+    }
+
+    #[test]
+    fn extract_min_ttl_from_response() {
+        let mut pkt = DnsPacket::new();
+        pkt.header.response = true;
+        pkt.answers.push(DnsRecord::A {
+            domain: "example.com".to_string(),
+            addr: std::net::Ipv4Addr::new(1, 2, 3, 4),
+            ttl: 300,
+        });
+        pkt.answers.push(DnsRecord::A {
+            domain: "example.com".to_string(),
+            addr: std::net::Ipv4Addr::new(5, 6, 7, 8),
+            ttl: 60,
+        });
+        let mut buf = BytePacketBuffer::new();
+        pkt.write(&mut buf).unwrap();
+        assert_eq!(extract_min_ttl(buf.filled()), 60);
+    }
+
+    #[test]
+    fn extract_min_ttl_no_answers() {
+        let mut pkt = DnsPacket::new();
+        pkt.header.response = true;
+        let mut buf = BytePacketBuffer::new();
+        pkt.write(&mut buf).unwrap();
+        assert_eq!(extract_min_ttl(buf.filled()), 0);
+    }
+
+    #[test]
+    fn serialize_formerr_response() {
+        let mut pkt = DnsPacket::new();
+        pkt.header.id = 0xABCD;
+        pkt.header.response = true;
+        pkt.header.rescode = ResultCode::FORMERR;
+        let resp = serialize_response(&pkt);
+        assert_eq!(resp.status(), StatusCode::OK);
+    }
+}