Feature/systemd query events (#1728)

* [service] Subscribe to systemd-resolver events

* [service] Add disabled state to the resolver

* [service] Add ETW DNS event listener

* [service] DNS listener refactoring

* [service] Add windows core dll project

* [service] DNSListener refactoring, small bugfixes

* [service] Change dns bypass rule

* [service] Update gitignore

* [service] Remove shim from integration module

* [service] Add DNS packet analyzer

* [service] Add self-check in dns monitor

* [service] Fix go linter errors

* [CI] Add github workflow for the windows core dll

* [service] Minor fixes to the dns monitor

service/firewall/interception/dnsmonitor/module.go

@@ -0,0 +1,138 @@
+package dnsmonitor
+
+import (
+	"errors"
+	"net"
+	"strings"
+
+	"github.com/miekg/dns"
+	"github.com/safing/portmaster/base/database"
+	"github.com/safing/portmaster/base/log"
+	"github.com/safing/portmaster/service/compat"
+	"github.com/safing/portmaster/service/integration"
+	"github.com/safing/portmaster/service/mgr"
+	"github.com/safing/portmaster/service/network/netutils"
+	"github.com/safing/portmaster/service/resolver"
+)
+
+var ResolverInfo = resolver.ResolverInfo{
+	Name: "SystemResolver",
+	Type: resolver.ServerTypeMonitor,
+}
+
+type DNSMonitor struct {
+	instance instance
+	mgr      *mgr.Manager
+
+	listener *Listener
+}
+
+// Manager returns the module manager.
+func (dl *DNSMonitor) Manager() *mgr.Manager {
+	return dl.mgr
+}
+
+// Start starts the module.
+func (dl *DNSMonitor) Start() error {
+	// Initialize dns event listener
+	var err error
+	dl.listener, err = newListener(dl)
+	if err != nil {
+		log.Errorf("dnsmonitor: failed to start dns listener: %s", err)
+	}
+
+	return nil
+}
+
+// Stop stops the module.
+func (dl *DNSMonitor) Stop() error {
+	if dl.listener != nil {
+		err := dl.listener.stop()
+		if err != nil {
+			log.Errorf("dnsmonitor: failed to close listener: %s", err)
+		}
+	}
+	return nil
+}
+
+// Flush flushes the buffer forcing all events to be processed.
+func (dl *DNSMonitor) Flush() error {
+	return dl.listener.flush()
+}
+
+func saveDomain(domain string, ips []net.IP, cnames map[string]string) {
+	fqdn := dns.Fqdn(domain)
+	// Create new record for this IP.
+	record := resolver.ResolvedDomain{
+		Domain:            fqdn,
+		Resolver:          &ResolverInfo,
+		DNSRequestContext: &resolver.DNSRequestContext{},
+		Expires:           0,
+	}
+
+	// Process cnames
+	record.AddCNAMEs(cnames)
+
+	// Add to cache
+	saveIPsInCache(ips, resolver.IPInfoProfileScopeGlobal, record)
+}
+
+func New(instance instance) (*DNSMonitor, error) {
+	// Initialize module
+	m := mgr.New("DNSMonitor")
+	module := &DNSMonitor{
+		mgr:      m,
+		instance: instance,
+	}
+
+	return module, nil
+}
+
+type instance interface {
+	OSIntegration() *integration.OSIntegration
+}
+
+func processIfSelfCheckDomain(fqdn string) bool {
+	// Check for compat check dns request.
+	if strings.HasSuffix(fqdn, compat.DNSCheckInternalDomainScope) {
+		subdomain := strings.TrimSuffix(fqdn, compat.DNSCheckInternalDomainScope)
+		_ = compat.SubmitDNSCheckDomain(subdomain)
+		log.Infof("dnsmonitor: self-check domain received")
+		// No need to parse the answer.
+		return true
+	}
+
+	return false
+}
+
+// saveIPsInCache saves the provided ips in the dns cashe assoseted with the record Domain and CNAMEs.
+func saveIPsInCache(ips []net.IP, profileID string, record resolver.ResolvedDomain) {
+	// Package IPs and CNAMEs into IPInfo structs.
+	for _, ip := range ips {
+		// Never save domain attributions for localhost IPs.
+		if netutils.GetIPScope(ip) == netutils.HostLocal {
+			continue
+		}
+
+		ipString := ip.String()
+		info, err := resolver.GetIPInfo(profileID, ipString)
+		if err != nil {
+			if !errors.Is(err, database.ErrNotFound) {
+				log.Errorf("dnsmonitor: failed to search for IP info record: %s", err)
+			}
+
+			info = &resolver.IPInfo{
+				IP:        ipString,
+				ProfileID: profileID,
+			}
+		}
+
+		// Add the new record to the resolved domains for this IP and scope.
+		info.AddDomain(record)
+
+		// Save if the record is new or has been updated.
+		if err := info.Save(); err != nil {
+			log.Errorf("dnsmonitor: failed to save IP info record: %s", err)
+		}
+	}
+}