Pull request: * all: move internal Go packages to internal/

Merge in DNS/adguard-home from 2234-move-to-internal to master

Squashed commit of the following:

commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Oct 30 12:44:18 2020 +0300

    * all: move internal Go packages to internal/

    Closes #2234.

internal/home/mobileconfig.go

@@ -0,0 +1,113 @@
+package home
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+
+	uuid "github.com/satori/go.uuid"
+	"howett.net/plist"
+)
+
+type DNSSettings struct {
+	DNSProtocol string
+	ServerURL   string `plist:",omitempty"`
+	ServerName  string `plist:",omitempty"`
+}
+
+type PayloadContent struct {
+	Name               string
+	PayloadDescription string
+	PayloadDisplayName string
+	PayloadIdentifier  string
+	PayloadType        string
+	PayloadUUID        string
+	PayloadVersion     int
+	DNSSettings        DNSSettings
+}
+
+type MobileConfig struct {
+	PayloadContent           []PayloadContent
+	PayloadDescription       string
+	PayloadDisplayName       string
+	PayloadIdentifier        string
+	PayloadRemovalDisallowed bool
+	PayloadType              string
+	PayloadUUID              string
+	PayloadVersion           int
+}
+
+func genUUIDv4() string {
+	return uuid.NewV4().String()
+}
+
+const (
+	dnsProtoHTTPS = "HTTPS"
+	dnsProtoTLS   = "TLS"
+)
+
+func getMobileConfig(d DNSSettings) ([]byte, error) {
+	var name string
+	switch d.DNSProtocol {
+	case dnsProtoHTTPS:
+		name = fmt.Sprintf("%s DoH", d.ServerName)
+	case dnsProtoTLS:
+		name = fmt.Sprintf("%s DoT", d.ServerName)
+	default:
+		return nil, fmt.Errorf("bad dns protocol %q", d.DNSProtocol)
+	}
+
+	data := MobileConfig{
+		PayloadContent: []PayloadContent{{
+			Name:               name,
+			PayloadDescription: "Configures device to use AdGuard Home",
+			PayloadDisplayName: name,
+			PayloadIdentifier:  fmt.Sprintf("com.apple.dnsSettings.managed.%s", genUUIDv4()),
+			PayloadType:        "com.apple.dnsSettings.managed",
+			PayloadUUID:        genUUIDv4(),
+			PayloadVersion:     1,
+			DNSSettings:        d,
+		}},
+		PayloadDescription:       "Adds AdGuard Home to Big Sur and iOS 14 or newer systems",
+		PayloadDisplayName:       name,
+		PayloadIdentifier:        genUUIDv4(),
+		PayloadRemovalDisallowed: false,
+		PayloadType:              "Configuration",
+		PayloadUUID:              genUUIDv4(),
+		PayloadVersion:           1,
+	}
+
+	return plist.MarshalIndent(data, plist.XMLFormat, "\t")
+}
+
+func handleMobileConfig(w http.ResponseWriter, d DNSSettings) {
+	mobileconfig, err := getMobileConfig(d)
+	if err != nil {
+		httpError(w, http.StatusInternalServerError, "plist.MarshalIndent: %s", err)
+	}
+
+	w.Header().Set("Content-Type", "application/xml")
+	_, _ = w.Write(mobileconfig)
+}
+
+func handleMobileConfigDoh(w http.ResponseWriter, r *http.Request) {
+	handleMobileConfig(w, DNSSettings{
+		DNSProtocol: dnsProtoHTTPS,
+		ServerURL:   fmt.Sprintf("https://%s/dns-query", r.Host),
+	})
+}
+
+func handleMobileConfigDot(w http.ResponseWriter, r *http.Request) {
+	var err error
+
+	var host string
+	host, _, err = net.SplitHostPort(r.Host)
+	if err != nil {
+		httpError(w, http.StatusBadRequest, "getting host: %s", err)
+	}
+
+	handleMobileConfig(w, DNSSettings{
+		DNSProtocol: dnsProtoTLS,
+		ServerName:  host,
+	})
+}