Merge pull request #139 from safing/fix/location-estimation

Fix location estimation on Windows

netenv/location.go

@@ -1,113 +1,162 @@
 package netenv
 
 import (
+	"errors"
 	"fmt"
-	"log"
 	"net"
-	"os"
+	"syscall"
 	"time"
 
-	"github.com/safing/portmaster/network/netutils"
+	"golang.org/x/net/ipv4"
 
 	"golang.org/x/net/icmp"
-	"golang.org/x/net/ipv4"
+
+	"github.com/safing/portbase/log"
+	"github.com/safing/portbase/rng"
+	"github.com/safing/portmaster/network/netutils"
 )
 
-// TODO: Create IPv6 version of GetApproximateInternetLocation
+var (
+	locationTestingIPv4     = "1.1.1.1"
+	locationTestingIPv4Addr *net.IPAddr
+)
 
-// GetApproximateInternetLocation returns the IP-address of the nearest ping-answering internet node
-//nolint:gocognit // TODO
-func GetApproximateInternetLocation() (net.IP, error) {
-	// TODO: first check if we have a public IP
-	// net.InterfaceAddrs()
+func prepLocation() (err error) {
+	locationTestingIPv4Addr, err = net.ResolveIPAddr("ip", locationTestingIPv4)
+	return err
+}
 
-	// Traceroute example
+// GetApproximateInternetLocation returns the nearest detectable IP address. If one or more global IP addresses are configured, one of them is returned. Currently only support IPv4. Else, the IP address of the nearest ping-answering internet node is returned.
+func GetApproximateInternetLocation() (net.IP, error) { //nolint:gocognit
+	// TODO: Create IPv6 version of GetApproximateInternetLocation
 
-	dst := net.IPAddr{
-		IP: net.IPv4(1, 1, 1, 1),
+	// First check if we have an assigned IPv6 address. Return that if available.
+	globalIPv4, _, err := GetAssignedGlobalAddresses()
+	if err != nil {
+		log.Warningf("netenv: location approximation: failed to get assigned global addresses: %s", err)
+	} else if len(globalIPv4) > 0 {
+		return globalIPv4[0], nil
 	}
 
-	c, err := net.ListenPacket("ip4:icmp", "0.0.0.0") // ICMP for IPv4
+	// Create OS specific ICMP Listener.
+	conn, err := newICMPListener(locationTestingIPv4)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to listen: %s", err)
 	}
-	defer c.Close()
+	defer conn.Close()
+	v4Conn := ipv4.NewPacketConn(conn)
 
-	p := ipv4.NewPacketConn(c)
-	err = p.SetControlMessage(ipv4.FlagTTL|ipv4.FlagSrc|ipv4.FlagDst|ipv4.FlagInterface, true)
+	// Generate a random ID for the ICMP packets.
+	msgID, err := rng.Number(0xFFFF) // uint16
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to generate ID: %s", err)
 	}
 
-	wm := icmp.Message{
-		Type: ipv4.ICMPTypeEcho, Code: 0,
+	// Create ICMP message body
+	pingMessage := icmp.Message{
+		Type: ipv4.ICMPTypeEcho,
+		Code: 0,
 		Body: &icmp.Echo{
-			ID:   os.Getpid() & 0xffff,
-			Data: []byte{0},
+			ID:   int(msgID),
+			Seq:  0, // increased before marshal
+			Data: []byte{},
 		},
 	}
-	rb := make([]byte, 1500)
+	recvBuffer := make([]byte, 1500)
+	maxHops := 4 // add one for every reply that is not global
 
 next:
-	for i := 1; i <= 64; i++ { // up to 64 hops
+	for i := 1; i <= maxHops; i++ {
 	repeat:
-		for j := 1; j <= 5; j++ {
-			wm.Body.(*icmp.Echo).Seq = i
+		for j := 1; j <= 2; j++ { // Try every hop twice.
+			// Increase sequence number.
+			pingMessage.Body.(*icmp.Echo).Seq++
 
-			wb, err := wm.Marshal(nil)
+			// Make packet data.
+			pingPacket, err := pingMessage.Marshal(nil)
 			if err != nil {
 				return nil, err
 			}
 
-			err = p.SetTTL(i)
+			// Set TTL on IP packet.
+			err = v4Conn.SetTTL(i)
 			if err != nil {
 				return nil, err
 			}
 
-			_, err = p.WriteTo(wb, nil, &dst)
-			if err != nil {
-				return nil, err
-			}
-
-			err = p.SetReadDeadline(time.Now().Add(10 * time.Millisecond))
-			if err != nil {
+			// Send ICMP packet.
+			if _, err := conn.WriteTo(pingPacket, locationTestingIPv4Addr); err != nil {
+				if neterr, ok := err.(*net.OpError); ok {
+					if neterr.Err == syscall.ENOBUFS {
+						continue
+					}
+				}
 				return nil, err
 			}
 
-			// n, cm, peer, err := p.ReadFrom(rb)
-			// readping:
+			// Listen for replies to the ICMP packet.
+		listen:
 			for {
+				// Set read timeout.
+				err = conn.SetReadDeadline(
+					time.Now().Add(
+						time.Duration(i*2+30) * time.Millisecond,
+					),
+				)
+				if err != nil {
+					return nil, err
+				}
 
-				n, _, peer, err := p.ReadFrom(rb)
+				// Read next packet.
+				n, src, err := conn.ReadFrom(recvBuffer)
 				if err != nil {
 					if err, ok := err.(net.Error); ok && err.Timeout() {
+						// Continue with next packet if we timeout
 						continue repeat
 					}
 					return nil, err
 				}
 
-				rm, err := icmp.ParseMessage(1, rb[:n])
+				// Parse remote IP address.
+				addr, ok := src.(*net.IPAddr)
+				if !ok {
+					return nil, fmt.Errorf("failed to parse IP: %s", src.String())
+				}
+
+				// Continue if we receive a packet from ourself. This is specific to Windows.
+				if me, err := IsMyIP(addr.IP); err == nil && me {
+					log.Tracef("netenv: location approximation: ignoring own message from %s", src)
+					continue listen
+				}
+
+				// If we received something from a global IP address, we have succeeded and can return immediately.
+				if netutils.IPIsGlobal(addr.IP) {
+					return addr.IP, nil
+				}
+
+				// For everey non-global reply received, increase the maximum hops to try.
+				maxHops++
+
+				// Parse the ICMP message.
+				icmpReply, err := icmp.ParseMessage(1, recvBuffer[:n])
 				if err != nil {
-					log.Fatal(err)
+					log.Warningf("netenv: location approximation: failed to parse ICMP message: %s", err)
+					continue listen
 				}
 
-				switch rm.Type {
-				case ipv4.ICMPTypeTimeExceeded:
-					ip := net.ParseIP(peer.String())
-					if ip == nil {
-						return nil, fmt.Errorf("failed to parse IP: %s", peer.String())
-					}
-					if !netutils.IPIsLAN(ip) {
-						return ip, nil
-					}
-					continue next
-				case ipv4.ICMPTypeEchoReply:
+				// React based on message type.
+				switch icmpReply.Type {
+				case ipv4.ICMPTypeTimeExceeded, ipv4.ICMPTypeEchoReply:
+					log.Tracef("netenv: location approximation: receveived %q from %s", icmpReply.Type, addr.IP)
 					continue next
+				case ipv4.ICMPTypeDestinationUnreachable:
+					return nil, fmt.Errorf("destination unreachable")
 				default:
-					// log.Tracef("unknown ICMP message: %+v\n", rm)
+					log.Tracef("netenv: location approximation: unexpected ICMP reply: received %q from %s", icmpReply.Type, addr.IP)
 				}
 			}
 		}
 	}
-	return nil, nil
+
+	return nil, errors.New("no usable response to any icmp message")
 }

netenv/location_default.go

@@ -0,0 +1,9 @@
+//+build !windows
+
+package netenv
+
+import "net"
+
+func newICMPListener(_ string) (net.PacketConn, error) {
+	return net.ListenPacket("ip4:icmp", "0.0.0.0")
+}

netenv/location_test.go

@@ -1,13 +1,29 @@
-// +build root
-
 package netenv
 
-import "testing"
+import (
+	"flag"
+	"testing"
+)
+
+var (
+	privileged bool
+)
+
+func init() {
+	flag.BoolVar(&privileged, "privileged", false, "run tests that require root/admin privileges")
+}
 
 func TestGetApproximateInternetLocation(t *testing.T) {
+	if testing.Short() {
+		t.Skip()
+	}
+	if !privileged {
+		t.Skip("skipping privileged test, active with -privileged argument")
+	}
+
 	ip, err := GetApproximateInternetLocation()
 	if err != nil {
-		t.Errorf("GetApproximateInternetLocation failed: %s", err)
+		t.Fatalf("GetApproximateInternetLocation failed: %s", err)
 	}
 	t.Logf("GetApproximateInternetLocation: %s", ip.String())
 }

netenv/location_windows.go

@@ -0,0 +1,61 @@
+package netenv
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+const (
+	SIO_RCVALL = syscall.IOC_IN | syscall.IOC_VENDOR | 1
+
+	RCVALL_OFF             = 0
+	RCVALL_ON              = 1
+	RCVALL_SOCKETLEVELONLY = 2
+	RCVALL_IPLEVEL         = 3
+)
+
+func newICMPListener(address string) (net.PacketConn, error) {
+	// This is an attempt to work around the problem described here:
+	// https://github.com/golang/go/issues/38427
+
+	// First, get the correct local interface address, as SIO_RCVALL can't be set on a 0.0.0.0 listeners.
+	dialedConn, err := net.Dial("ip4:icmp", address)
+	if err != nil {
+		return nil, fmt.Errorf("failed to dial: %s", err)
+	}
+	localAddr := dialedConn.LocalAddr()
+	dialedConn.Close()
+
+	// Configure the setup routine in order to extract the socket handle.
+	var socketHandle syscall.Handle
+	cfg := net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			return c.Control(func(s uintptr) {
+				socketHandle = syscall.Handle(s)
+			})
+		},
+	}
+
+	// Bind to interface.
+	conn, err := cfg.ListenPacket(context.Background(), "ip4:icmp", localAddr.String())
+	if err != nil {
+		return nil, err
+	}
+
+	// Set socket option to receive all packets, such as ICMP error messages.
+	// This is somewhat dirty, as there is guarantee that socketHandle is still valid.
+	// WARNING: The Windows Firewall might just drop the incoming packets you might want to receive.
+	unused := uint32(0) // Documentation states that this is unused, but WSAIoctl fails without it.
+	flag := uint32(RCVALL_IPLEVEL)
+	size := uint32(unsafe.Sizeof(flag))
+	err = syscall.WSAIoctl(socketHandle, SIO_RCVALL, (*byte)(unsafe.Pointer(&flag)), size, nil, 0, &unused, nil, 0)
+	if err != nil {
+		return nil, fmt.Errorf("failed to set socket to listen to all packests: %s", os.NewSyscallError("WSAIoctl", err))
+	}
+
+	return conn, nil
+}

netenv/main.go

@@ -21,7 +21,11 @@ func init() {
 }
 
 func prep() error {
-	return prepOnlineStatus()
+	if err := prepOnlineStatus(); err != nil {
+		return err
+	}
+
+	return prepLocation()
 }
 
 func start() error {

netenv/online-status.go

@@ -35,7 +35,7 @@ const (
 
 // Online Status and Resolver
 var (
-	PortalTestIP  = net.IPv4(255, 255, 255, 254)
+	PortalTestIP  = net.IPv4(192, 0, 2, 1)
 	PortalTestURL = fmt.Sprintf("http://%s/", PortalTestIP)
 
 	DNSTestDomain     = "one.one.one.one."

network/clean.go

@@ -75,7 +75,10 @@ func cleanConnections() (activePIDs map[int]struct{}) {
 				if !exists {
 					// Step 2: mark end
 					conn.Ended = nowUnix
-					conn.Save()
+					if conn.KeyIsSet() {
+						// Be absolutely sure that we have a key set here, else conn.Save() will deadlock.
+						conn.Save()
+					}
 				}
 			case conn.Ended < deleteOlderThan:
 				// Step 3: delete