Enum UpstreamTransport 

pub enum UpstreamTransport {
    Do53Udp,
    Do53Tcp,
    Dot,
    Doh,
    Doq,
}

Upstream transport selector. Production callers populate this from DnsAuthority::resolvers[].protocol; operators in dev / CI override via the CELLOS_DNS_UPSTREAM_TRANSPORT env var (see UpstreamTransport::from_env).

Default = Do53Udp so the existing UDP-only behaviour is the no-op upgrade path — adding the transport field to super::DnsProxyConfig does not change behaviour for cells that don’t explicitly opt into a non-default value.

Variants

Do53Udp

Plain UDP/53 (legacy default, byte-identical to pre-A6 forward path).

Do53Tcp

Plain TCP/53 with the conventional 2-byte length prefix.

Dot

DNS-over-TLS (RFC 7858). Length-prefixed framing inside a TLS 1.2/1.3 tunnel.

Doh

DNS-over-HTTPS (RFC 8484). reqwest POST with application/dns-message framing. URL configured via UpstreamExtras::doh_url (default Cloudflare).

Doq

DNS-over-QUIC (RFC 9250). quinn 0.11 bidi stream with the same 2-byte length prefix as DoT. Server + port configured via UpstreamExtras::doq_server / UpstreamExtras::doq_port (default 1.1.1.1:853).

Implementations

impl UpstreamTransport

pub fn parse(s: &str) -> Option<Self>

Parse a textual transport selector. Case-insensitive; accepts the canonical contract names (do53-udp, do53-tcp, dot, doh, doq) AND the common aliases operators reach for (udp, tcp, tls, https, quic).

Returns None for unrecognised input. The caller is expected to fail-closed (refuse to construct the cell) rather than silently fall back to UDP, so we don’t pretend to know what the operator meant.

pub fn from_env() -> Option<Self>

Read the upstream transport selector from the process environment and parse it. Two env var names are accepted (in priority order):

1. CELLOS_DNS_UPSTREAM_PROTOCOL — the contract-aligned name (matches DnsAuthority::resolvers[].protocol). Preferred.
2. CELLOS_DNS_UPSTREAM_TRANSPORT — the original legacy name, preserved so existing operator scripts and integration tests keep working byte-for-byte.

Unset returns Some(Do53Udp) (the default). Set-but-unparseable returns None so the caller can refuse to start.

pub fn label(self) -> &'static str

Stable string label suitable for stamping into events / logs. Used in UpstreamError::TransportNotEnabled’s Display.

Trait Implementations

impl Clone for UpstreamTransport

fn clone(&self) -> UpstreamTransport

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for UpstreamTransport

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for UpstreamTransport

fn default() -> UpstreamTransport

Returns the “default value” for a type.

impl PartialEq for UpstreamTransport

fn eq(&self, other: &UpstreamTransport) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for UpstreamTransport

impl Eq for UpstreamTransport

impl StructuralPartialEq for UpstreamTransport