Create interface for socket info structs, fix caching bug

From PR Review https://github.com/safing/portmaster/pull/72

network/proc/findpid.go

@@ -21,31 +21,18 @@ var (
 	pidsByUser     = make(map[int][]int)
 )
 
-// FindConnectionPID returns the pid of the given socket info.
-func FindConnectionPID(socketInfo *socket.ConnectionInfo) (pid int) {
+// GetPID returns the already existing pid of the given socket info or searches for it.
+// This also acts as a getter for socket.*Info.PID, as locking for that occurs here.
+func GetPID(socketInfo socket.Info) (pid int) {
 	pidsByUserLock.Lock()
 	defer pidsByUserLock.Unlock()
 
-	if socketInfo.PID != socket.UnidentifiedProcessID {
-		return socket.UnidentifiedProcessID
+	if socketInfo.GetPID() != socket.UnidentifiedProcessID {
+		return socketInfo.GetPID()
 	}
 
-	pid = findPID(socketInfo.UID, socketInfo.Inode)
-	socketInfo.PID = pid
-	return pid
-}
-
-// FindBindPID returns the pid of the given socket info.
-func FindBindPID(socketInfo *socket.BindInfo) (pid int) {
-	pidsByUserLock.Lock()
-	defer pidsByUserLock.Unlock()
-
-	if socketInfo.PID != socket.UnidentifiedProcessID {
-		return socket.UnidentifiedProcessID
-	}
-
-	pid = findPID(socketInfo.UID, socketInfo.Inode)
-	socketInfo.PID = pid
+	pid = findPID(socketInfo.GetUID(), socketInfo.GetInode())
+	socketInfo.SetPID(pid)
 	return pid
 }
 
@@ -175,6 +162,9 @@ entryLoop:
 
 }
 
+// readDirNames only reads the directory names. Using ioutil.ReadDir() would call `lstat` on every
+// resulting directory name, which we don't need. This function will be called a lot, so we should
+// refrain from unnecessary work.
 func readDirNames(dir string) (names []string) {
 	file, err := os.Open(dir)
 	if err != nil {

network/proc/tables_test.go

@@ -14,12 +14,12 @@ func TestSockets(t *testing.T) {
 	}
 	fmt.Println("\nTCP 4 connections:")
 	for _, connection := range connections {
-		pid := FindConnectionPID(connection)
+		pid := GetPID(connection)
 		fmt.Printf("%d: %+v\n", pid, connection)
 	}
 	fmt.Println("\nTCP 4 listeners:")
 	for _, listener := range listeners {
-		pid := FindBindPID(listener)
+		pid := GetPID(listener)
 		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 := FindConnectionPID(connection)
+		pid := GetPID(connection)
 		fmt.Printf("%d: %+v\n", pid, connection)
 	}
 	fmt.Println("\nTCP 6 listeners:")
 	for _, listener := range listeners {
-		pid := FindBindPID(listener)
+		pid := GetPID(listener)
 		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 := FindBindPID(bind)
+		pid := GetPID(bind)
 		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 := FindBindPID(bind)
+		pid := GetPID(bind)
 		fmt.Printf("%d: %+v\n", pid, bind)
 	}
 }

network/socket/socket.go

@@ -29,3 +29,35 @@ type Address struct {
 	IP   net.IP
 	Port uint16
 }
+
+// Info is a generic interface to both ConnectionInfo and BindInfo.
+type Info interface {
+	GetPID() int
+	SetPID(int)
+	GetUID() int
+	GetInode() int
+}
+
+// GetPID returns the PID.
+func (i *ConnectionInfo) GetPID() int { return i.PID }
+
+// SetPID sets the PID to the given value.
+func (i *ConnectionInfo) SetPID(pid int) { i.PID = pid }
+
+// GetUID returns the UID.
+func (i *ConnectionInfo) GetUID() int { return i.UID }
+
+// GetInode returns the Inode.
+func (i *ConnectionInfo) GetInode() int { return i.Inode }
+
+// GetPID returns the PID.
+func (i *BindInfo) GetPID() int { return i.PID }
+
+// SetPID sets the PID to the given value.
+func (i *BindInfo) SetPID(pid int) { i.PID = pid }
+
+// GetUID returns the UID.
+func (i *BindInfo) GetUID() int { return i.UID }
+
+// GetInode returns the Inode.
+func (i *BindInfo) GetInode() int { return i.Inode }

network/state/lookup.go

@@ -81,7 +81,7 @@ func (table *tcpTable) lookup(pktInfo *packet.Info) (
 			if localPort == socketInfo.Local.Port &&
 				(socketInfo.Local.IP[0] == 0 || localIP.Equal(socketInfo.Local.IP)) {
 				table.lock.RUnlock()
-				return checkBindPID(socketInfo, true)
+				return checkPID(socketInfo, true)
 			}
 		}
 
@@ -90,7 +90,7 @@ func (table *tcpTable) lookup(pktInfo *packet.Info) (
 			if localPort == socketInfo.Local.Port &&
 				localIP.Equal(socketInfo.Local.IP) {
 				table.lock.RUnlock()
-				return checkConnectionPID(socketInfo, false)
+				return checkPID(socketInfo, false)
 			}
 		}
 
@@ -138,12 +138,12 @@ func (table *udpTable) lookup(pktInfo *packet.Info) (
 
 				// do not check direction if remoteIP/Port is not given
 				if pktInfo.RemotePort() == 0 {
-					return checkBindPID(socketInfo, pktInfo.Inbound)
+					return checkPID(socketInfo, pktInfo.Inbound)
 				}
 
 				// get direction and return
 				connInbound := table.getDirection(socketInfo, pktInfo)
-				return checkBindPID(socketInfo, connInbound)
+				return checkPID(socketInfo, connInbound)
 			}
 		}
 

network/state/system_linux.go

@@ -14,30 +14,10 @@ var (
 	getUDP6Table = proc.GetUDP6Table
 )
 
-func checkConnectionPID(socketInfo *socket.ConnectionInfo, connInbound bool) (pid int, inbound bool, err error) {
+func checkPID(socketInfo socket.Info, connInbound bool) (pid int, inbound bool, err error) {
 	for i := 0; i <= lookupRetries; i++ {
 		// look for PID
-		pid = proc.FindConnectionPID(socketInfo)
-		if pid != socket.UnidentifiedProcessID {
-			// if we found a PID, return
-			break
-		}
-
-		// every time, except for the last iteration
-		if i < lookupRetries {
-			// we found no PID, we could have been too fast, give the kernel some time to think
-			// back off timer: with 3ms baseWaitTime: 3, 6, 9, 12, 15, 18, 21ms - 84ms in total
-			time.Sleep(time.Duration(i+1) * baseWaitTime)
-		}
-	}
-
-	return pid, connInbound, nil
-}
-
-func checkBindPID(socketInfo *socket.BindInfo, connInbound bool) (pid int, inbound bool, err error) {
-	for i := 0; i <= lookupRetries; i++ {
-		// look for PID
-		pid = proc.FindBindPID(socketInfo)
+		pid = proc.GetPID(socketInfo)
 		if pid != socket.UnidentifiedProcessID {
 			// if we found a PID, return
 			break