Struct UpstreamExtras 

pub struct UpstreamExtras {
    pub dot_sni: Option<String>,
    pub dot_server: Option<String>,
    pub dot_port: Option<u16>,
    pub doh_url: Option<String>,
    pub doq_server: Option<String>,
    pub doq_port: Option<u16>,
}

Optional per-transport extras the caller may supply alongside UpstreamTransport. Populated by super::DnsProxyConfig::upstream_extras in production; tests construct via Default::default() and then set only the fields they care about.

All fields are optional so the do53-udp hot path doesn’t require any extras to function — unused fields incur zero cost.

Fields

dot_sni: Option<String>

SNI hostname presented during the DoT TLS handshake. When None, rustls is given the resolver’s IP literal — most public DoT resolvers (1.1.1.1 / 8.8.8.8) ship a cert that covers both the hostname and the IP, but operators with a private resolver will need to set this to the cert’s CN/SAN.

dot_server: Option<String>

Operator-supplied DoT server host. When set (typically populated from the CELLOS_DNS_UPSTREAM_DOT_SERVER env var), the supervisor pre-resolves this to a SocketAddr and substitutes the proxy’s upstream_addr, so the DoT roundtrip targets the operator’s choice rather than the spec’s do53 resolver. None falls back to the spec resolver’s IP.

Plain string here (not pre-resolved) so the config struct stays transport-agnostic and the resolution step lives in the composition root where DNS bootstrap is allowed.

dot_port: Option<u16>

Operator-supplied DoT port (RFC 7858 default = 853). Paired with Self::dot_server; when None the supervisor defaults to 853.

doh_url: Option<String>

DNS-DOH-2 — operator-supplied DoH endpoint URL. When None the DoH forward path defaults to [DEFAULT_DOH_URL]. Sourced from CELLOS_DNS_UPSTREAM_DOH_URL in production. Must be a full https://… URL including the /dns-query path; reqwest validates the scheme on first call and surfaces a typed [UpstreamError::Io(InvalidInput)] if it’s malformed.

doq_server: Option<String>

DNS-DOQ-2 — operator-supplied DoQ server (IP literal or hostname). None → default 1.1.1.1. Sourced from CELLOS_DNS_UPSTREAM_DOQ_SERVER. Hostnames are passed through to tokio::net::lookup_host (which uses the OS resolver, NOT the supervisor’s bootstrap path) — operators should prefer IP literals for the same reason DoT does (see [parse_dot_target]).

doq_port: Option<u16>

DNS-DOQ-2 — operator-supplied DoQ port. None → default 853 (RFC 9250). Sourced from CELLOS_DNS_UPSTREAM_DOQ_PORT.

Implementations

impl UpstreamExtras

pub fn from_env() -> Self

Read the DoT-specific operator overrides from the process environment.

Recognised env vars:

• CELLOS_DNS_UPSTREAM_DOT_SERVER — host (IP literal or hostname) for the DoT upstream. Default unset (caller falls back to the spec resolver’s IP, or to 1.1.1.1 if the caller has no spec to fall back on).
• CELLOS_DNS_UPSTREAM_DOT_PORT — TCP port. Default unset (caller falls back to 853 per RFC 7858).
• CELLOS_DNS_UPSTREAM_DOT_SNI — explicit SNI hostname. Default unset (rustls receives the resolver’s IP literal as ServerName).

Unparseable port values are silently ignored (the field stays None) rather than failing — operators get the default behaviour instead of a refused cell. Strict parsing is the supervisor’s job at the composition site if it wants to gate startup on a typo.

Trait Implementations

impl Clone for UpstreamExtras

fn clone(&self) -> UpstreamExtras

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for UpstreamExtras

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

Formats the value using the given formatter.

impl Default for UpstreamExtras

fn default() -> UpstreamExtras

Returns the “default value” for a type.