wip: migrate to mono-repo. SPN has already been moved to spn/

service/resolver/failing.go

@@ -0,0 +1,125 @@
+package resolver
+
+import (
+	"context"
+	"time"
+
+	"github.com/safing/portbase/log"
+	"github.com/safing/portbase/modules"
+	"github.com/safing/portmaster/service/netenv"
+)
+
+var (
+	// FailThreshold is amount of errors a resolvers must experience in order to be regarded as failed.
+	FailThreshold = 5
+
+	// FailObserveDuration is the duration in which failures are counted in order to mark a resolver as failed.
+	FailObserveDuration = time.Duration(FailThreshold) * 10 * time.Second
+)
+
+// IsFailing returns if this resolver is currently failing.
+func (brc *BasicResolverConn) IsFailing() bool {
+	return brc.failing.IsSet()
+}
+
+// ReportFailure reports that an error occurred with this resolver.
+func (brc *BasicResolverConn) ReportFailure() {
+	// Don't mark resolver as failed if we are offline.
+	if !netenv.Online() {
+		return
+	}
+
+	// Ingore report when we are already failing.
+	if brc.IsFailing() {
+		return
+	}
+
+	brc.failLock.Lock()
+	defer brc.failLock.Unlock()
+
+	// Check if we are within the observation period.
+	if time.Since(brc.failingStarted) > FailObserveDuration {
+		brc.fails = 1
+		brc.failingStarted = time.Now()
+		return
+	}
+
+	// Increase and check if we need to set to failing.
+	brc.fails++
+	if brc.fails > FailThreshold {
+		brc.failing.Set()
+	}
+
+	// Report to netenv that a configured server failed.
+	if brc.resolver.Info.Source == ServerSourceConfigured {
+		netenv.ConnectedToDNS.UnSet()
+	}
+}
+
+// ResetFailure resets the failure status.
+func (brc *BasicResolverConn) ResetFailure() {
+	if brc.failing.SetToIf(true, false) {
+		brc.failLock.Lock()
+		defer brc.failLock.Unlock()
+		brc.fails = 0
+		brc.failingStarted = time.Time{}
+	}
+
+	// Report to netenv that a configured server succeeded.
+	if brc.resolver.Info.Source == ServerSourceConfigured {
+		netenv.ConnectedToDNS.Set()
+	}
+}
+
+func checkFailingResolvers(ctx context.Context, task *modules.Task) error {
+	var resolvers []*Resolver
+
+	// Make a copy of the resolver list.
+	func() {
+		resolversLock.Lock()
+		defer resolversLock.Unlock()
+
+		resolvers = make([]*Resolver, len(globalResolvers))
+		copy(resolvers, globalResolvers)
+	}()
+
+	// Start logging.
+	ctx, tracer := log.AddTracer(ctx)
+	tracer.Debugf("resolver: checking failed resolvers")
+	defer tracer.Submit()
+
+	// Go through all resolvers and check if they are reachable again.
+	for i, resolver := range resolvers {
+		// Skip resolver that are not failing.
+		if !resolver.Conn.IsFailing() {
+			continue
+		}
+
+		tracer.Tracef("resolver: testing failed resolver [%d/%d] %s", i+1, len(resolvers), resolver)
+
+		// Test if we can resolve via this resolver.
+		ips, _, err := testConnectivity(ctx, netenv.DNSTestDomain, resolver)
+		switch {
+		case err != nil:
+			tracer.Debugf("resolver: failed resolver %s is still failing: %s", resolver, err)
+		case len(ips) == 0 || !ips[0].Equal(netenv.DNSTestExpectedIP):
+			tracer.Debugf("resolver: failed resolver %s received unexpected A records: %s", resolver, ips)
+		default:
+			// Resolver test successful.
+			tracer.Infof("resolver: check successful, resolver %s is available again", resolver)
+			resolver.Conn.ResetFailure()
+		}
+
+		// Check if context was canceled.
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+	}
+
+	// Set next execution time.
+	if task != nil {
+		task.Schedule(time.Now().Add(time.Duration(nameserverRetryRate()) * time.Second))
+	}
+
+	return nil
+}