safing-portmaster/service/firewall/interception/dnsmonitor/etwlink_windows.go
Vladimir Stoilov 1a1bc14804
Feature/systemd query events ()
* [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
2024-11-27 17:10:47 +02:00

99 lines
2.5 KiB
Go

//go:build windows
// +build windows
package dnsmonitor
import (
"fmt"
"runtime"
"sync"
"sync/atomic"
"github.com/safing/portmaster/service/integration"
"golang.org/x/sys/windows"
)
type ETWSession struct {
i integration.ETWFunctions
shutdownGuard atomic.Bool
shutdownMutex sync.Mutex
state uintptr
}
// NewSession creates new ETW event listener and initilizes it. This is a low level interface, make sure to call DestorySession when you are done using it.
func NewSession(etwInterface integration.ETWFunctions, callback func(domain string, result string)) (*ETWSession, error) {
etwSession := &ETWSession{
i: etwInterface,
}
// Make sure session from previous instances are not running.
_ = etwSession.i.StopOldSession()
// Initialize notification activated callback
win32Callback := windows.NewCallback(func(domain *uint16, result *uint16) uintptr {
callback(windows.UTF16PtrToString(domain), windows.UTF16PtrToString(result))
return 0
})
// The function only allocates memory it will not fail.
etwSession.state = etwSession.i.CreateState(win32Callback)
// Make sure DestroySession is called even if caller forgets to call it.
runtime.SetFinalizer(etwSession, func(s *ETWSession) {
_ = s.i.DestroySession(s.state)
})
// Initialize session.
err := etwSession.i.InitializeSession(etwSession.state)
if err != nil {
return nil, fmt.Errorf("failed to initialzie session: %q", err)
}
return etwSession, nil
}
// StartTrace starts the tracing session of dns events. This is a blocking call. It will not return until the trace is stopped.
func (l *ETWSession) StartTrace() error {
return l.i.StartTrace(l.state)
}
// IsRunning returns true if DestroySession has NOT been called.
func (l *ETWSession) IsRunning() bool {
return !l.shutdownGuard.Load()
}
// FlushTrace flushes the trace buffer.
func (l *ETWSession) FlushTrace() error {
l.shutdownMutex.Lock()
defer l.shutdownMutex.Unlock()
// Make sure session is still running.
if l.shutdownGuard.Load() {
return nil
}
return l.i.FlushTrace(l.state)
}
// StopTrace stopes the trace. This will cause StartTrace to return.
func (l *ETWSession) StopTrace() error {
return l.i.StopTrace(l.state)
}
// DestroySession closes the session and frees the allocated memory. Listener cannot be used after this function is called.
func (l *ETWSession) DestroySession() error {
l.shutdownMutex.Lock()
defer l.shutdownMutex.Unlock()
if l.shutdownGuard.Swap(true) {
return nil
}
err := l.i.DestroySession(l.state)
if err != nil {
return err
}
l.state = 0
return nil
}