Method cacheWorks

proxy/proxy.go:786–815

cacheWorks returns true if the cache works for the given context. If not, it returns false and logs the reason why.

(dctx *DNSContext)

// cacheWorks returns true if the cache works for the given context.  If not, it
// returns false and logs the reason why.
func (p *Proxy) cacheWorks(dctx *DNSContext) (ok bool) {
	var reason string
	switch {
	case dctx.CustomUpstreamConfig != nil && dctx.CustomUpstreamConfig.cache == nil:
		// If custom upstreams are used but the custom upstream cache is
		// disabled, return false to prevent storing results in the global
		// cache.
		//
		// See https://github.com/AdguardTeam/dnsproxy/issues/169.
		reason = "custom upstreams cache is not configured"
	case p.cache == nil &&
		(dctx.CustomUpstreamConfig == nil || dctx.CustomUpstreamConfig.cache == nil):
		reason = "caching disabled: neither global cache nor custom upstreams cache is configured"
	case dctx.RequestedPrivateRDNS != netip.Prefix{}:
		// Don't cache the requests intended for local upstream servers, those
		// should be fast enough as is.
		reason = "requested address is private"
	case dctx.Req.CheckingDisabled:
		// Also don't lookup the cache for responses with DNSSEC checking
		// disabled since only validated responses are cached and those may be
		// not the desired result for user specifying CD flag.
		reason = "dnssec check disabled"
	default:
		return true
	}

	p.logger.Debug("not caching", "reason", reason)

	return false
}

// processECS adds EDNS Client Subnet data into the request from d.
func (dctx *DNSContext) processECS(cliIP net.IP, l *slog.Logger) {