Implement review suggestions

nameserver/nameserver.go

@@ -169,7 +169,7 @@ func handleRequest(ctx context.Context, w dns.ResponseWriter, query *dns.Msg) er
 	}
 
 	// start tracer
-	ctx, tracer := log.AddTracer(context.Background())
+	ctx, tracer := log.AddTracer(ctx)
 	defer tracer.Submit()
 	tracer.Tracef("nameserver: handling new request for %s%s from %s:%d, getting connection", q.FQDN, q.QType, remoteAddr.IP, remoteAddr.Port)
 

network/connection.go

@@ -37,7 +37,7 @@ type Connection struct { //nolint:maligned // TODO: fix alignment
 	process    *process.Process
 
 	// remote endpoint
-	Entity *intel.Entity // needs locking, instance is never shared
+	Entity *intel.Entity
 
 	Verdict       Verdict
 	Reason        string

network/iphelper/get.go

@@ -8,13 +8,12 @@ import (
 	"github.com/safing/portmaster/network/socket"
 )
 
-const (
-	unidentifiedProcessID = -1
-)
-
 var (
 	ipHelper *IPHelper
-	lock     sync.RWMutex
+
+	// lock locks access to the whole DLL.
+	// TODO: It's unproven if we can access the iphlpapi.dll concurrently, especially as we might be encountering various versions of the DLL. In the future, we could possibly investigate and improve performance here.
+	lock sync.RWMutex
 )
 
 // GetTCP4Table returns the system table for IPv4 TCP activity.

network/iphelper/tables.go

@@ -214,7 +214,7 @@ func (ipHelper *IPHelper) getTable(ipVersion, protocol uint8) (connections []*so
 				binds = append(binds, &socket.BindInfo{
 					Local: socket.Address{
 						IP:   convertIPv4(row.localAddr),
-						Port: uint16(row.localPort>>8 | row.localPort<<8),
+						Port: convertPort(row.localPort),
 					},
 					PID: int(row.owningPid),
 				})
@@ -222,11 +222,11 @@ func (ipHelper *IPHelper) getTable(ipVersion, protocol uint8) (connections []*so
 				connections = append(connections, &socket.ConnectionInfo{
 					Local: socket.Address{
 						IP:   convertIPv4(row.localAddr),
-						Port: uint16(row.localPort>>8 | row.localPort<<8),
+						Port: convertPort(row.localPort),
 					},
 					Remote: socket.Address{
 						IP:   convertIPv4(row.remoteAddr),
-						Port: uint16(row.remotePort>>8 | row.remotePort<<8),
+						Port: convertPort(row.remotePort),
 					},
 					PID: int(row.owningPid),
 				})
@@ -243,7 +243,7 @@ func (ipHelper *IPHelper) getTable(ipVersion, protocol uint8) (connections []*so
 				binds = append(binds, &socket.BindInfo{
 					Local: socket.Address{
 						IP:   net.IP(row.localAddr[:]),
-						Port: uint16(row.localPort>>8 | row.localPort<<8),
+						Port: convertPort(row.localPort),
 					},
 					PID: int(row.owningPid),
 				})
@@ -251,11 +251,11 @@ func (ipHelper *IPHelper) getTable(ipVersion, protocol uint8) (connections []*so
 				connections = append(connections, &socket.ConnectionInfo{
 					Local: socket.Address{
 						IP:   net.IP(row.localAddr[:]),
-						Port: uint16(row.localPort>>8 | row.localPort<<8),
+						Port: convertPort(row.localPort),
 					},
 					Remote: socket.Address{
 						IP:   net.IP(row.remoteAddr[:]),
-						Port: uint16(row.remotePort>>8 | row.remotePort<<8),
+						Port: convertPort(row.remotePort),
 					},
 					PID: int(row.owningPid),
 				})
@@ -271,7 +271,7 @@ func (ipHelper *IPHelper) getTable(ipVersion, protocol uint8) (connections []*so
 			binds = append(binds, &socket.BindInfo{
 				Local: socket.Address{
 					IP:   convertIPv4(row.localAddr),
-					Port: uint16(row.localPort>>8 | row.localPort<<8),
+					Port: convertPort(row.localPort),
 				},
 				PID: int(row.owningPid),
 			})
@@ -286,7 +286,7 @@ func (ipHelper *IPHelper) getTable(ipVersion, protocol uint8) (connections []*so
 			binds = append(binds, &socket.BindInfo{
 				Local: socket.Address{
 					IP:   net.IP(row.localAddr[:]),
-					Port: uint16(row.localPort>>8 | row.localPort<<8),
+					Port: convertPort(row.localPort),
 				},
 				PID: int(row.owningPid),
 			})
@@ -303,3 +303,8 @@ func convertIPv4(input uint32) net.IP {
 	binary.LittleEndian.PutUint32(addressBuf, input)
 	return net.IP(addressBuf)
 }
+
+// convertPort converts ports received from iphlpapi.dll
+func convertPort(input uint32) uint16 {
+	return uint16(input>>8 | input<<8)
+}

network/proc/findpid.go

@@ -10,11 +10,9 @@ import (
 	"sync"
 	"syscall"
 
-	"github.com/safing/portbase/log"
+	"github.com/safing/portmaster/network/socket"
-)
 
-const (
+	"github.com/safing/portbase/log"
-	unidentifiedProcessID = -1
 )
 
 var (
@@ -23,7 +21,7 @@ var (
 )
 
 // FindPID returns the pid of the given uid and socket inode.
-func FindPID(uid, inode int) (pid int, ok bool) { //nolint:gocognit // TODO
+func FindPID(uid, inode int) (pid int) { //nolint:gocognit // TODO
 	pidsByUserLock.Lock()
 	defer pidsByUserLock.Unlock()
 
@@ -42,7 +40,7 @@ func FindPID(uid, inode int) (pid int, ok bool) { //nolint:gocognit // TODO
 		var checkedUserPids []int
 		for _, possiblePID := range pids {
 			if findSocketFromPid(possiblePID, inode) {
-				return possiblePID, true
+				return possiblePID
 			}
 			checkedUserPids = append(checkedUserPids, possiblePID)
 		}
@@ -61,7 +59,7 @@ func FindPID(uid, inode int) (pid int, ok bool) { //nolint:gocognit // TODO
 				// only check if not already checked
 				if sort.SearchInts(checkedUserPids, possiblePID) == len {
 					if findSocketFromPid(possiblePID, inode) {
-						return possiblePID, true
+						return possiblePID
 					}
 				}
 			}
@@ -75,13 +73,13 @@ func FindPID(uid, inode int) (pid int, ok bool) { //nolint:gocognit // TODO
 		if possibleUID != uid {
 			for _, possiblePID := range pids {
 				if findSocketFromPid(possiblePID, inode) {
-					return possiblePID, true
+					return possiblePID
 				}
 			}
 		}
 	}
 
-	return unidentifiedProcessID, false
+	return socket.UnidentifiedProcessID
 }
 
 func findSocketFromPid(pid, inode int) bool {

network/proc/tables.go

@@ -5,6 +5,7 @@ package proc
 import (
 	"bufio"
 	"encoding/hex"
+	"fmt"
 	"net"
 	"os"
 	"strconv"
@@ -43,12 +44,10 @@ const (
 	ICMP4
 	ICMP6
 
-	TCP4Data  = "/proc/net/tcp"
+	tcp4ProcFile = "/proc/net/tcp"
-	UDP4Data  = "/proc/net/udp"
+	tcp6ProcFile = "/proc/net/tcp6"
-	TCP6Data  = "/proc/net/tcp6"
+	udp4ProcFile = "/proc/net/udp"
-	UDP6Data  = "/proc/net/udp6"
+	udp6ProcFile = "/proc/net/udp6"
-	ICMP4Data = "/proc/net/icmp"
-	ICMP6Data = "/proc/net/icmp6"
 
 	UnfetchedProcessID = -2
 
@@ -57,27 +56,47 @@ const (
 
 // GetTCP4Table returns the system table for IPv4 TCP activity.
 func GetTCP4Table() (connections []*socket.ConnectionInfo, listeners []*socket.BindInfo, err error) {
-	return getTableFromSource(TCP4, TCP4Data, convertIPv4)
+	return getTableFromSource(TCP4, tcp4ProcFile)
 }
 
 // GetTCP6Table returns the system table for IPv6 TCP activity.
 func GetTCP6Table() (connections []*socket.ConnectionInfo, listeners []*socket.BindInfo, err error) {
-	return getTableFromSource(TCP6, TCP6Data, convertIPv6)
+	return getTableFromSource(TCP6, tcp6ProcFile)
 }
 
 // GetUDP4Table returns the system table for IPv4 UDP activity.
 func GetUDP4Table() (binds []*socket.BindInfo, err error) {
-	_, binds, err = getTableFromSource(UDP4, UDP4Data, convertIPv4)
+	_, binds, err = getTableFromSource(UDP4, udp4ProcFile)
 	return
 }
 
 // GetUDP6Table returns the system table for IPv6 UDP activity.
 func GetUDP6Table() (binds []*socket.BindInfo, err error) {
-	_, binds, err = getTableFromSource(UDP6, UDP6Data, convertIPv6)
+	_, binds, err = getTableFromSource(UDP6, udp6ProcFile)
 	return
 }
 
-func getTableFromSource(stack uint8, procFile string, ipConverter func(string) net.IP) (connections []*socket.ConnectionInfo, binds []*socket.BindInfo, err error) {
+const (
+	// hint: we split fields by multiple delimiters, see procDelimiter
+	fieldIndexLocalIP    = 1
+	fieldIndexLocalPort  = 2
+	fieldIndexRemoteIP   = 3
+	fieldIndexRemotePort = 4
+	fieldIndexUID        = 11
+	fieldIndexInode      = 13
+)
+
+func getTableFromSource(stack uint8, procFile string) (connections []*socket.ConnectionInfo, binds []*socket.BindInfo, err error) {
+
+	var ipConverter func(string) net.IP
+	switch stack {
+	case TCP4, UDP4:
+		ipConverter = convertIPv4
+	case TCP6, UDP6:
+		ipConverter = convertIPv6
+	default:
+		return nil, nil, fmt.Errorf("unsupported table stack: %d", stack)
+	}
 
 	// open file
 	socketData, err := os.Open(procFile)
@@ -91,36 +110,36 @@ func getTableFromSource(stack uint8, procFile string, ipConverter func(string) n
 	scanner.Split(bufio.ScanLines)
 
 	// parse
-	scanner.Scan() // skip first line
+	scanner.Scan() // skip first row
 	for scanner.Scan() {
-		line := strings.FieldsFunc(scanner.Text(), procDelimiter)
+		fields := strings.FieldsFunc(scanner.Text(), procDelimiter)
-		if len(line) < 14 {
+		if len(fields) < 14 {
-			// log.Tracef("process: too short: %s", line)
+			// log.Tracef("process: too short: %s", fields)
 			continue
 		}
 
-		localIP := ipConverter(line[1])
+		localIP := ipConverter(fields[fieldIndexLocalIP])
 		if localIP == nil {
 			continue
 		}
 
-		localPort, err := strconv.ParseUint(line[2], 16, 16)
+		localPort, err := strconv.ParseUint(fields[fieldIndexLocalPort], 16, 16)
 		if err != nil {
 			log.Warningf("process: could not parse port: %s", err)
 			continue
 		}
 
-		uid, err := strconv.ParseInt(line[11], 10, 32)
+		uid, err := strconv.ParseInt(fields[fieldIndexUID], 10, 32)
-		// log.Tracef("uid: %s", line[11])
+		// log.Tracef("uid: %s", fields[fieldIndexUID])
 		if err != nil {
-			log.Warningf("process: could not parse uid %s: %s", line[11], err)
+			log.Warningf("process: could not parse uid %s: %s", fields[11], err)
 			continue
 		}
 
-		inode, err := strconv.ParseInt(line[13], 10, 32)
+		inode, err := strconv.ParseInt(fields[fieldIndexInode], 10, 32)
-		// log.Tracef("inode: %s", line[13])
+		// log.Tracef("inode: %s", fields[fieldIndexInode])
 		if err != nil {
-			log.Warningf("process: could not parse inode %s: %s", line[13], err)
+			log.Warningf("process: could not parse inode %s: %s", fields[13], err)
 			continue
 		}
 
@@ -139,7 +158,7 @@ func getTableFromSource(stack uint8, procFile string, ipConverter func(string) n
 
 		case TCP4, TCP6:
 
-			if line[5] == tcpListenStateHex {
+			if fields[5] == tcpListenStateHex {
 				// listener
 
 				binds = append(binds, &socket.BindInfo{
@@ -154,12 +173,12 @@ func getTableFromSource(stack uint8, procFile string, ipConverter func(string) n
 			} else {
 				// connection
 
-				remoteIP := ipConverter(line[3])
+				remoteIP := ipConverter(fields[fieldIndexRemoteIP])
 				if remoteIP == nil {
 					continue
 				}
 
-				remotePort, err := strconv.ParseUint(line[4], 16, 16)
+				remotePort, err := strconv.ParseUint(fields[fieldIndexRemotePort], 16, 16)
 				if err != nil {
 					log.Warningf("process: could not parse port: %s", err)
 					continue

network/proc/tables_test.go

@@ -14,12 +14,12 @@ func TestSockets(t *testing.T) {
 	}
 	fmt.Println("\nTCP 4 connections:")
 	for _, connection := range connections {
-		pid, _ := FindPID(connection.UID, connection.Inode)
+		pid := FindPID(connection.UID, connection.Inode)
 		fmt.Printf("%d: %+v\n", pid, connection)
 	}
 	fmt.Println("\nTCP 4 listeners:")
 	for _, listener := range listeners {
-		pid, _ := FindPID(listener.UID, listener.Inode)
+		pid := FindPID(listener.UID, listener.Inode)
 		fmt.Printf("%d: %+v\n", pid, listener)
 	}
 
@@ -29,12 +29,12 @@ func TestSockets(t *testing.T) {
 	}
 	fmt.Println("\nTCP 6 connections:")
 	for _, connection := range connections {
-		pid, _ := FindPID(connection.UID, connection.Inode)
+		pid := FindPID(connection.UID, connection.Inode)
 		fmt.Printf("%d: %+v\n", pid, connection)
 	}
 	fmt.Println("\nTCP 6 listeners:")
 	for _, listener := range listeners {
-		pid, _ := FindPID(listener.UID, listener.Inode)
+		pid := FindPID(listener.UID, listener.Inode)
 		fmt.Printf("%d: %+v\n", pid, listener)
 	}
 
@@ -44,7 +44,7 @@ func TestSockets(t *testing.T) {
 	}
 	fmt.Println("\nUDP 4 binds:")
 	for _, bind := range binds {
-		pid, _ := FindPID(bind.UID, bind.Inode)
+		pid := FindPID(bind.UID, bind.Inode)
 		fmt.Printf("%d: %+v\n", pid, bind)
 	}
 
@@ -54,7 +54,7 @@ func TestSockets(t *testing.T) {
 	}
 	fmt.Println("\nUDP 6 binds:")
 	for _, bind := range binds {
-		pid, _ := FindPID(bind.UID, bind.Inode)
+		pid := FindPID(bind.UID, bind.Inode)
 		fmt.Printf("%d: %+v\n", pid, bind)
 	}
 }

network/socket/socket.go

@@ -2,6 +2,11 @@ package socket
 
 import "net"
 
+const (
+	// UnidentifiedProcessID is originally defined in the process pkg, but duplicated here because of import loops.
+	UnidentifiedProcessID = -1
+)
+
 // ConnectionInfo holds socket information returned by the system.
 type ConnectionInfo struct {
 	Local  Address

network/state/exists.go

@@ -11,7 +11,11 @@ const (
 	UDPConnectionTTL = 10 * time.Minute
 )
 
+// Exists checks if the given connection is present in the system state tables.
 func Exists(pktInfo *packet.Info, now time.Time) (exists bool) {
+
+	// TODO: create lookup maps before running a flurry of Exists() checks.
+
 	switch {
 	case pktInfo.Version == packet.IPv4 && pktInfo.Protocol == packet.TCP:
 		tcp4Lock.Lock()
@@ -76,7 +80,10 @@ func existsUDP(
 		if localPort == socketInfo.Local.Port &&
 			(socketInfo.Local.IP[0] == 0 || localIP.Equal(socketInfo.Local.IP)) {
 
-			udpConnState, ok := getUDPConnState(socketInfo, udpStates, remoteIP, remotePort)
+			udpConnState, ok := getUDPConnState(socketInfo, udpStates, socket.Address{
+				IP:   remoteIP,
+				Port: remotePort,
+			})
 			switch {
 			case !ok:
 				return false

network/state/lookup.go

@@ -24,10 +24,6 @@ import (
 //       - switch direction to outbound if outbound packet is seen?
 // - IP: Unidentified Process
 
-const (
-	UnidentifiedProcessID = -1
-)
-
 // Errors
 var (
 	ErrConnectionNotFound = errors.New("could not find connection in system state tables")
@@ -75,7 +71,7 @@ func Lookup(pktInfo *packet.Info) (pid int, inbound bool, err error) {
 		return searchUDP(udp6Binds, udp6States, updateUDP6Table, pktInfo)
 
 	default:
-		return UnidentifiedProcessID, false, errors.New("unsupported protocol for finding process")
+		return socket.UnidentifiedProcessID, false, errors.New("unsupported protocol for finding process")
 	}
 }
 
@@ -119,7 +115,7 @@ func searchTCP(
 		connections, listeners = updateTables()
 	}
 
-	return UnidentifiedProcessID, false, ErrConnectionNotFound
+	return socket.UnidentifiedProcessID, false, ErrConnectionNotFound
 }
 
 func searchUDP(
@@ -170,5 +166,5 @@ func searchUDP(
 		binds = updateTable()
 	}
 
-	return UnidentifiedProcessID, pktInfo.Inbound, ErrConnectionNotFound
+	return socket.UnidentifiedProcessID, pktInfo.Inbound, ErrConnectionNotFound
 }

network/state/system_linux.go

@@ -14,24 +14,14 @@ var (
 
 func checkConnectionPID(socketInfo *socket.ConnectionInfo, connInbound bool) (pid int, inbound bool, err error) {
 	if socketInfo.PID == proc.UnfetchedProcessID {
-		pid, ok := proc.FindPID(socketInfo.UID, socketInfo.Inode)
+		socketInfo.PID = proc.FindPID(socketInfo.UID, socketInfo.Inode)
-		if ok {
-			socketInfo.PID = pid
-		} else {
-			socketInfo.PID = UnidentifiedProcessID
-		}
 	}
 	return socketInfo.PID, connInbound, nil
 }
 
 func checkBindPID(socketInfo *socket.BindInfo, connInbound bool) (pid int, inbound bool, err error) {
 	if socketInfo.PID == proc.UnfetchedProcessID {
-		pid, ok := proc.FindPID(socketInfo.UID, socketInfo.Inode)
+		socketInfo.PID = proc.FindPID(socketInfo.UID, socketInfo.Inode)
-		if ok {
-			socketInfo.PID = pid
-		} else {
-			socketInfo.PID = UnidentifiedProcessID
-		}
 	}
 	return socketInfo.PID, connInbound, nil
 }

network/state/tables.go

@@ -18,9 +18,8 @@ var (
 )
 
 func updateTCP4Tables() (connections []*socket.ConnectionInfo, listeners []*socket.BindInfo) {
-	// FIXME: repeatable once
+	var err error
-
+	connections, listeners, err = getTCP4Table()
-	connections, listeners, err := getTCP4Table()
 	if err != nil {
 		log.Warningf("state: failed to get TCP4 socket table: %s", err)
 		return
@@ -28,11 +27,12 @@ func updateTCP4Tables() (connections []*socket.ConnectionInfo, listeners []*sock
 
 	tcp4Connections = connections
 	tcp4Listeners = listeners
-	return tcp4Connections, tcp4Listeners
+	return
 }
 
 func updateTCP6Tables() (connections []*socket.ConnectionInfo, listeners []*socket.BindInfo) {
-	connections, listeners, err := getTCP6Table()
+	var err error
+	connections, listeners, err = getTCP6Table()
 	if err != nil {
 		log.Warningf("state: failed to get TCP6 socket table: %s", err)
 		return
@@ -40,27 +40,29 @@ func updateTCP6Tables() (connections []*socket.ConnectionInfo, listeners []*sock
 
 	tcp6Connections = connections
 	tcp6Listeners = listeners
-	return tcp6Connections, tcp6Listeners
+	return
 }
 
 func updateUDP4Table() (binds []*socket.BindInfo) {
-	binds, err := getUDP4Table()
+	var err error
+	binds, err = getUDP4Table()
 	if err != nil {
 		log.Warningf("state: failed to get UDP4 socket table: %s", err)
 		return
 	}
 
 	udp4Binds = binds
-	return udp4Binds
+	return
 }
 
 func updateUDP6Table() (binds []*socket.BindInfo) {
-	binds, err := getUDP6Table()
+	var err error
+	binds, err = getUDP6Table()
 	if err != nil {
 		log.Warningf("state: failed to get UDP6 socket table: %s", err)
 		return
 	}
 
 	udp6Binds = binds
-	return udp6Binds
+	return
 }

network/state/udp.go

@@ -2,7 +2,6 @@ package state
 
 import (
 	"context"
-	"net"
 	"time"
 
 	"github.com/safing/portmaster/network/packet"
@@ -15,7 +14,7 @@ type udpState struct {
 }
 
 const (
-	UpdConnStateTTL             = 72 * time.Hour
+	UdpConnStateTTL             = 72 * time.Hour
 	UdpConnStateShortenedTTL    = 3 * time.Hour
 	AggressiveCleaningThreshold = 256
 )
@@ -25,10 +24,10 @@ var (
 	udp6States = make(map[string]map[string]*udpState) // locked with udp6Lock
 )
 
-func getUDPConnState(socketInfo *socket.BindInfo, udpStates map[string]map[string]*udpState, remoteIP net.IP, remotePort uint16) (udpConnState *udpState, ok bool) {
+func getUDPConnState(socketInfo *socket.BindInfo, udpStates map[string]map[string]*udpState, remoteAddress socket.Address) (udpConnState *udpState, ok bool) {
-	bindMap, ok := udpStates[makeUDPStateKey(socketInfo.Local.IP, socketInfo.Local.Port)]
+	bindMap, ok := udpStates[makeUDPStateKey(socketInfo.Local)]
 	if ok {
-		udpConnState, ok = bindMap[makeUDPStateKey(remoteIP, remotePort)]
+		udpConnState, ok = bindMap[makeUDPStateKey(remoteAddress)]
 		return
 	}
 
@@ -36,7 +35,7 @@ func getUDPConnState(socketInfo *socket.BindInfo, udpStates map[string]map[strin
 }
 
 func getUDPDirection(socketInfo *socket.BindInfo, udpStates map[string]map[string]*udpState, pktInfo *packet.Info) (connDirection bool) {
-	localKey := makeUDPStateKey(socketInfo.Local.IP, socketInfo.Local.Port)
+	localKey := makeUDPStateKey(socketInfo.Local)
 
 	bindMap, ok := udpStates[localKey]
 	if !ok {
@@ -44,7 +43,10 @@ func getUDPDirection(socketInfo *socket.BindInfo, udpStates map[string]map[strin
 		udpStates[localKey] = bindMap
 	}
 
-	remoteKey := makeUDPStateKey(pktInfo.RemoteIP(), pktInfo.RemotePort())
+	remoteKey := makeUDPStateKey(socket.Address{
+		IP:   pktInfo.RemoteIP(),
+		Port: pktInfo.RemotePort(),
+	})
 	udpConnState, ok := bindMap[remoteKey]
 	if !ok {
 		bindMap[remoteKey] = &udpState{
@@ -79,19 +81,18 @@ func cleanStates(
 	now time.Time,
 ) {
 	// compute thresholds
-	threshold := now.Add(-UpdConnStateTTL)
+	threshold := now.Add(-UdpConnStateTTL)
 	shortThreshhold := now.Add(-UdpConnStateShortenedTTL)
 
-	// make list of all active keys
+	// make lookup map of all active keys
 	bindKeys := make(map[string]struct{})
 	for _, socketInfo := range binds {
-		bindKeys[makeUDPStateKey(socketInfo.Local.IP, socketInfo.Local.Port)] = struct{}{}
+		bindKeys[makeUDPStateKey(socketInfo.Local)] = struct{}{}
 	}
 
 	// clean the udp state storage
 	for localKey, bindMap := range udpStates {
-		_, active := bindKeys[localKey]
+		if _, active := bindKeys[localKey]; active {
-		if active {
 			// clean old entries
 			for remoteKey, udpConnState := range bindMap {
 				if udpConnState.lastSeen.Before(threshold) {
@@ -113,7 +114,7 @@ func cleanStates(
 	}
 }
 
-func makeUDPStateKey(ip net.IP, port uint16) string {
+func makeUDPStateKey(address socket.Address) string {
 	// This could potentially go wrong, but as all IPs are created by the same source, everything should be fine.
-	return string(ip) + string(port)
+	return string(address.IP) + string(address.Port)
 }

ui/module.go

@@ -29,6 +29,14 @@ func prep() error {
 }
 
 func start() error {
+	// Create a dummy directory to which processes change their working directory
+	// to. Currently this includes the App and the Notifier. The aim is protect
+	// all other directories and increase compatibility should any process want
+	// to read or write something to the current working directory. This can also
+	// be useful in the future to dump data to for debugging. The permission used
+	// may seem dangerous, but proper permission on the parent directory provide
+	// (some) protection.
+	// Processes must _never_ read from this directory.
 	err := dataroot.Root().ChildDir("exec", 0777).Ensure()
 	if err != nil {
 		log.Warningf("ui: failed to create safe exec dir: %s", err)