platform: modularize api/gui, add docs-tests-web foundation, and refresh root config

selective-vpn-api/app/dns_settings_handlers_upstreams.go

@@ -0,0 +1,61 @@
+package app
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+)
+
+// ---------------------------------------------------------------------
+// EN: `handleDNSUpstreams` is an HTTP handler for dns upstreams.
+// RU: `handleDNSUpstreams` - HTTP-обработчик для dns upstreams.
+// ---------------------------------------------------------------------
+func handleDNSUpstreams(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodGet:
+		writeJSON(w, http.StatusOK, loadDNSUpstreamsConf())
+	case http.MethodPost:
+		var cfg DNSUpstreams
+		if r.Body != nil {
+			defer r.Body.Close()
+			if err := json.NewDecoder(io.LimitReader(r.Body, 1<<20)).Decode(&cfg); err != nil && err != io.EOF {
+				http.Error(w, "bad json", http.StatusBadRequest)
+				return
+			}
+		}
+		if err := saveDNSUpstreamsConf(cfg); err != nil {
+			http.Error(w, "write error", http.StatusInternalServerError)
+			return
+		}
+		writeJSON(w, http.StatusOK, map[string]any{
+			"ok":  true,
+			"cfg": loadDNSUpstreamsConf(),
+		})
+	default:
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+	}
+}
+
+func handleDNSUpstreamPool(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodGet:
+		items := loadDNSUpstreamPoolState()
+		writeJSON(w, http.StatusOK, DNSUpstreamPoolState{Items: items})
+	case http.MethodPost:
+		var body DNSUpstreamPoolState
+		if r.Body != nil {
+			defer r.Body.Close()
+			if err := json.NewDecoder(io.LimitReader(r.Body, 1<<20)).Decode(&body); err != nil && err != io.EOF {
+				http.Error(w, "bad json", http.StatusBadRequest)
+				return
+			}
+		}
+		if err := saveDNSUpstreamPoolState(body.Items); err != nil {
+			http.Error(w, "write error", http.StatusInternalServerError)
+			return
+		}
+		writeJSON(w, http.StatusOK, DNSUpstreamPoolState{Items: loadDNSUpstreamPoolState()})
+	default:
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+	}
+}