Add lock timeout for remote action (fixes #466) (#468)

When the remove window size is expanded, a condition is waited on until
the remote server acknowledges and completes the action. If the server
does not respond, e.g. due to a connectivity issue, then this blocks the
client indefinitely. Instead the client waits up to the connection's
timeout (500 min default) and fails. This allows users to set a reasonable
timeout, fail their operations, and retry accordingly.

src/main/java/net/schmizz/sshj/connection/channel/AbstractChannel.java

@@ -102,7 +102,8 @@ protected AbstractChannel(Connection conn, String type, Charset remoteCharset) {
 
     protected void init(int recipient, long remoteWinSize, long remoteMaxPacketSize) {
         this.recipient = recipient;
-        rwin = new Window.Remote(remoteWinSize, (int) Math.min(remoteMaxPacketSize, REMOTE_MAX_PACKET_SIZE_CEILING), loggerFactory);
+        rwin = new Window.Remote(remoteWinSize, (int) Math.min(remoteMaxPacketSize, REMOTE_MAX_PACKET_SIZE_CEILING),
+            conn.getTimeoutMs(), loggerFactory);
         out = new ChannelOutputStream(this, trans, rwin);
         log.debug("Initialized - {}", this);
     }

src/main/java/net/schmizz/sshj/connection/channel/Window.java

@@ -20,6 +20,8 @@
 import net.schmizz.sshj.connection.ConnectionException;
 import org.slf4j.Logger;
 
+import java.util.concurrent.TimeUnit;
+
 public abstract class Window {
 
     protected final Logger log;
@@ -73,17 +75,23 @@ public String toString() {
     /** Controls how much data we can send before an adjustment notification from remote end is required. */
     public static final class Remote
             extends Window {
+        private final long timeoutMs;
 
-        public Remote(long initialWinSize, int maxPacketSize, LoggerFactory loggerFactory) {
+        public Remote(long initialWinSize, int maxPacketSize, long timeoutMs, LoggerFactory loggerFactory) {
             super(initialWinSize, maxPacketSize, loggerFactory);
+            this.timeoutMs = timeoutMs;
         }
 
         public long awaitExpansion(long was) throws ConnectionException {
             synchronized (lock) {
+                long end = System.nanoTime() + TimeUnit.MILLISECONDS.toNanos(timeoutMs);
                 while (size <= was) {
                     log.debug("Waiting, need size to grow from {} bytes", was);
                     try {
-                        lock.wait();
+                        lock.wait(timeoutMs);
+                        if ((size <= was) && ((System.nanoTime() - end) > 0)) {
+                            throw new ConnectionException("Timeout when trying to expand the window size");
+                        }
                     } catch (InterruptedException ie) {
                         throw new ConnectionException(ie);
                     }