[client] Update local interface addresses when gathering candidates (#3324)

client/internal/stdnet/stdnet.go

@@ -5,11 +5,16 @@ package stdnet
 
 import (
 	"fmt"
+	"slices"
+	"sync"
+	"time"
 
 	"github.com/pion/transport/v3"
 	"github.com/pion/transport/v3/stdnet"
 )
 
+const updateInterval = 30 * time.Second
+
 // Net is an implementation of the net.Net interface
 // based on functions of the standard net package.
 type Net struct {
@@ -18,6 +23,10 @@ type Net struct {
 	iFaceDiscover iFaceDiscover
 	// interfaceFilter should return true if the given interfaceName is allowed
 	interfaceFilter func(interfaceName string) bool
+	lastUpdate      time.Time
+
+	// mu is shared between interfaces and lastUpdate
+	mu sync.Mutex
 }
 
 // NewNetWithDiscover creates a new StdNet instance.
@@ -43,18 +52,40 @@ func NewNet(disallowList []string) (*Net, error) {
 // The interfaces are discovered by an external iFaceDiscover function or by a default discoverer if the external one
 // wasn't specified.
 func (n *Net) UpdateInterfaces() (err error) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	return n.updateInterfaces()
+}
+
+func (n *Net) updateInterfaces() (err error) {
 	allIfaces, err := n.iFaceDiscover.iFaces()
 	if err != nil {
 		return err
 	}
+
 	n.interfaces = n.filterInterfaces(allIfaces)
+
+	n.lastUpdate = time.Now()
+
 	return nil
 }
 
 // Interfaces returns a slice of interfaces which are available on the
 // system
 func (n *Net) Interfaces() ([]*transport.Interface, error) {
-	return n.interfaces, nil
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	if time.Since(n.lastUpdate) < updateInterval {
+		return slices.Clone(n.interfaces), nil
+	}
+
+	if err := n.updateInterfaces(); err != nil {
+		return nil, fmt.Errorf("update interfaces: %w", err)
+	}
+
+	return slices.Clone(n.interfaces), nil
 }
 
 // InterfaceByIndex returns the interface specified by index.
@@ -63,6 +94,8 @@ func (n *Net) Interfaces() ([]*transport.Interface, error) {
 // sharing the logical data link; for more precision use
 // InterfaceByName.
 func (n *Net) InterfaceByIndex(index int) (*transport.Interface, error) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
 	for _, ifc := range n.interfaces {
 		if ifc.Index == index {
 			return ifc, nil
@@ -74,6 +107,8 @@ func (n *Net) InterfaceByIndex(index int) (*transport.Interface, error) {
 
 // InterfaceByName returns the interface specified by name.
 func (n *Net) InterfaceByName(name string) (*transport.Interface, error) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
 	for _, ifc := range n.interfaces {
 		if ifc.Name == name {
 			return ifc, nil
@@ -87,7 +122,7 @@ func (n *Net) filterInterfaces(interfaces []*transport.Interface) []*transport.I
 	if n.interfaceFilter == nil {
 		return interfaces
 	}
-	result := []*transport.Interface{}
+	var result []*transport.Interface
 	for _, iface := range interfaces {
 		if n.interfaceFilter(iface.Name) {
 			result = append(result, iface)