Pull request: websvc-config-manager

Merge in DNS/adguard-home from websvc-config-manager to master

Squashed commit of the following:

commit 2143b47c6528030dfe059172888fddf9061e42da
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Oct 4 14:50:47 2022 +0300

    next: add config manager

internal/next/websvc/dns.go

@@ -0,0 +1,84 @@
+package websvc
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/netip"
+	"time"
+
+	"github.com/AdguardTeam/AdGuardHome/internal/next/dnssvc"
+)
+
+// DNS Settings Handlers
+
+// ReqPatchSettingsDNS describes the request to the PATCH /api/v1/settings/dns
+// HTTP API.
+type ReqPatchSettingsDNS struct {
+	// TODO(a.garipov): Add more as we go.
+
+	Addresses        []netip.AddrPort `json:"addresses"`
+	BootstrapServers []string         `json:"bootstrap_servers"`
+	UpstreamServers  []string         `json:"upstream_servers"`
+	UpstreamTimeout  JSONDuration     `json:"upstream_timeout"`
+}
+
+// HTTPAPIDNSSettings are the DNS settings as used by the HTTP API.  See the
+// DnsSettings object in the OpenAPI specification.
+type HTTPAPIDNSSettings struct {
+	// TODO(a.garipov): Add more as we go.
+
+	Addresses        []netip.AddrPort `json:"addresses"`
+	BootstrapServers []string         `json:"bootstrap_servers"`
+	UpstreamServers  []string         `json:"upstream_servers"`
+	UpstreamTimeout  JSONDuration     `json:"upstream_timeout"`
+}
+
+// handlePatchSettingsDNS is the handler for the PATCH /api/v1/settings/dns HTTP
+// API.
+func (svc *Service) handlePatchSettingsDNS(w http.ResponseWriter, r *http.Request) {
+	req := &ReqPatchSettingsDNS{
+		Addresses:        []netip.AddrPort{},
+		BootstrapServers: []string{},
+		UpstreamServers:  []string{},
+	}
+
+	// TODO(a.garipov): Validate nulls and proper JSON patch.
+
+	err := json.NewDecoder(r.Body).Decode(&req)
+	if err != nil {
+		writeJSONErrorResponse(w, r, fmt.Errorf("decoding: %w", err))
+
+		return
+	}
+
+	newConf := &dnssvc.Config{
+		Addresses:        req.Addresses,
+		BootstrapServers: req.BootstrapServers,
+		UpstreamServers:  req.UpstreamServers,
+		UpstreamTimeout:  time.Duration(req.UpstreamTimeout),
+	}
+
+	ctx := r.Context()
+	err = svc.confMgr.UpdateDNS(ctx, newConf)
+	if err != nil {
+		writeJSONErrorResponse(w, r, fmt.Errorf("updating: %w", err))
+
+		return
+	}
+
+	newSvc := svc.confMgr.DNS()
+	err = newSvc.Start()
+	if err != nil {
+		writeJSONErrorResponse(w, r, fmt.Errorf("starting new service: %w", err))
+
+		return
+	}
+
+	writeJSONOKResponse(w, r, &HTTPAPIDNSSettings{
+		Addresses:        newConf.Addresses,
+		BootstrapServers: newConf.BootstrapServers,
+		UpstreamServers:  newConf.UpstreamServers,
+		UpstreamTimeout:  JSONDuration(newConf.UpstreamTimeout),
+	})
+}