Function newDoHReq

proxy/serverhttps.go:133–186

newDoHReq returns new DNS request parsed from the given HTTP request. In case of invalid request returns nil and the suitable status code for an HTTP error response. l must not be nil.

(
	ctx context.Context,
	r *http.Request,
	l *slog.Logger,
)

// case of invalid request returns nil and the suitable status code for an HTTP
// error response.  l must not be nil.
func newDoHReq(
	ctx context.Context,
	r *http.Request,
	l *slog.Logger,
) (req *dns.Msg, statusCode int) {
	var buf []byte
	var err error

	switch r.Method {
	case http.MethodGet:
		dnsParam := r.URL.Query().Get("dns")
		buf, err = base64.RawURLEncoding.DecodeString(dnsParam)
		if len(buf) == 0 || err != nil {
			l.DebugContext(
				ctx,
				"parsing dns request from http get param",
				"param_name", dnsParam,
				slogutil.KeyError, err,
			)

			return nil, http.StatusBadRequest
		}
	case http.MethodPost:
		contentType := r.Header.Get(httphdr.ContentType)
		if contentType != "application/dns-message" {
			l.DebugContext(ctx, "unsupported media type", "content_type", contentType)

			return nil, http.StatusUnsupportedMediaType
		}

		limitBody := ioutil.LimitReader(r.Body, dns.MaxMsgSize)
		buf, err = io.ReadAll(limitBody)
		if err != nil {
			l.DebugContext(ctx, "reading http request body", slogutil.KeyError, err)

			return nil, http.StatusBadRequest
		}

		defer slogutil.CloseAndLog(ctx, l, r.Body, slog.LevelDebug)
	default:
		l.DebugContext(ctx, "bad http method", "method", r.Method)

		return nil, http.StatusMethodNotAllowed
	}

	req = &dns.Msg{}
	if err = req.Unpack(buf); err != nil {
		l.DebugContext(ctx, "unpacking http msg", slogutil.KeyError, err)

		return nil, http.StatusBadRequest
	}

	return req, http.StatusOK
}

// ServeHTTP is the http.Handler implementation that handles DoH queries.
//