[client] Use stdnet with a context to avoid DNS deadlocks (#4781)

client/internal/stdnet/stdnet.go

@@ -4,17 +4,28 @@
 package stdnet
 
 import (
+	"context"
+	"errors"
 	"fmt"
+	"net"
+	"net/netip"
 	"slices"
+	"strconv"
 	"sync"
 	"time"
 
-	"github.com/netbirdio/netbird/client/iface/netstack"
 	"github.com/pion/transport/v3"
 	"github.com/pion/transport/v3/stdnet"
+
+	"github.com/netbirdio/netbird/client/iface/netstack"
 )
 
-const updateInterval = 30 * time.Second
+const (
+	updateInterval    = 30 * time.Second
+	dnsResolveTimeout = 30 * time.Second
+)
+
+var errNoSuitableAddress = errors.New("no suitable address found")
 
 // Net is an implementation of the net.Net interface
 // based on functions of the standard net package.
@@ -28,12 +39,19 @@ type Net struct {
 
 	// mu is shared between interfaces and lastUpdate
 	mu sync.Mutex
+
+	// ctx is the context for network operations that supports cancellation
+	ctx context.Context
 }
 
 // NewNetWithDiscover creates a new StdNet instance.
-func NewNetWithDiscover(iFaceDiscover ExternalIFaceDiscover, disallowList []string) (*Net, error) {
+func NewNetWithDiscover(ctx context.Context, iFaceDiscover ExternalIFaceDiscover, disallowList []string) (*Net, error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
 	n := &Net{
 		interfaceFilter: InterfaceFilter(disallowList),
+		ctx:             ctx,
 	}
 	// current ExternalIFaceDiscover implement in android-client https://github.dev/netbirdio/android-client
 	// so in android cli use pionDiscover
@@ -46,14 +64,64 @@ func NewNetWithDiscover(iFaceDiscover ExternalIFaceDiscover, disallowList []stri
 }
 
 // NewNet creates a new StdNet instance.
-func NewNet(disallowList []string) (*Net, error) {
+func NewNet(ctx context.Context, disallowList []string) (*Net, error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
 	n := &Net{
 		iFaceDiscover:   pionDiscover{},
 		interfaceFilter: InterfaceFilter(disallowList),
+		ctx:             ctx,
 	}
 	return n, n.UpdateInterfaces()
 }
 
+// resolveAddr performs DNS resolution with context support and timeout.
+func (n *Net) resolveAddr(network, address string) (netip.AddrPort, error) {
+	host, portStr, err := net.SplitHostPort(address)
+	if err != nil {
+		return netip.AddrPort{}, err
+	}
+
+	port, err := strconv.Atoi(portStr)
+	if err != nil {
+		return netip.AddrPort{}, fmt.Errorf("invalid port: %w", err)
+	}
+	if port < 0 || port > 65535 {
+		return netip.AddrPort{}, fmt.Errorf("invalid port: %d", port)
+	}
+
+	ipNet := "ip"
+	switch network {
+	case "tcp4", "udp4":
+		ipNet = "ip4"
+	case "tcp6", "udp6":
+		ipNet = "ip6"
+	}
+
+	if host == "" {
+		addr := netip.IPv4Unspecified()
+		if ipNet == "ip6" {
+			addr = netip.IPv6Unspecified()
+		}
+		return netip.AddrPortFrom(addr, uint16(port)), nil
+	}
+
+	ctx, cancel := context.WithTimeout(n.ctx, dnsResolveTimeout)
+	defer cancel()
+
+	addrs, err := net.DefaultResolver.LookupNetIP(ctx, ipNet, host)
+	if err != nil {
+		return netip.AddrPort{}, err
+	}
+
+	if len(addrs) == 0 {
+		return netip.AddrPort{}, errNoSuitableAddress
+	}
+
+	return netip.AddrPortFrom(addrs[0], uint16(port)), nil
+}
+
 // UpdateInterfaces updates the internal list of network interfaces
 // and associated addresses filtering them by name.
 // The interfaces are discovered by an external iFaceDiscover function or by a default discoverer if the external one
@@ -137,3 +205,39 @@ func (n *Net) filterInterfaces(interfaces []*transport.Interface) []*transport.I
 	}
 	return result
 }
+
+// ResolveUDPAddr resolves UDP addresses with context support and timeout.
+func (n *Net) ResolveUDPAddr(network, address string) (*net.UDPAddr, error) {
+	switch network {
+	case "udp", "udp4", "udp6":
+	case "":
+		network = "udp"
+	default:
+		return nil, &net.OpError{Op: "resolve", Net: network, Err: net.UnknownNetworkError(network)}
+	}
+
+	addrPort, err := n.resolveAddr(network, address)
+	if err != nil {
+		return nil, &net.OpError{Op: "resolve", Net: network, Addr: &net.UDPAddr{IP: nil}, Err: err}
+	}
+
+	return net.UDPAddrFromAddrPort(addrPort), nil
+}
+
+// ResolveTCPAddr resolves TCP addresses with context support and timeout.
+func (n *Net) ResolveTCPAddr(network, address string) (*net.TCPAddr, error) {
+	switch network {
+	case "tcp", "tcp4", "tcp6":
+	case "":
+		network = "tcp"
+	default:
+		return nil, &net.OpError{Op: "resolve", Net: network, Err: net.UnknownNetworkError(network)}
+	}
+
+	addrPort, err := n.resolveAddr(network, address)
+	if err != nil {
+		return nil, &net.OpError{Op: "resolve", Net: network, Addr: &net.TCPAddr{IP: nil}, Err: err}
+	}
+
+	return net.TCPAddrFromAddrPort(addrPort), nil
+}