Support writing unsigned integers to buffer

src/main/java/net/schmizz/sshj/common/Buffer.java

@@ -306,6 +306,23 @@ public long readUInt32()
                 data[rpos++] & 0x000000ffL;
     }
 
+    /**
+     * Writes a uint32 integer
+     *
+     * @param uint32
+     *
+     * @return this
+     */
+    @SuppressWarnings("unchecked")
+    public T putUInt32FromInt(int uint32) {
+        ensureCapacity(4);
+        data[wpos++] = (byte) (uint32 >> 24);
+        data[wpos++] = (byte) (uint32 >> 16);
+        data[wpos++] = (byte) (uint32 >> 8);
+        data[wpos++] = (byte) uint32;
+        return (T) this;
+    }
+
     /**
      * Writes a uint32 integer
      *

src/main/java/net/schmizz/sshj/connection/ConnectionImpl.java

@@ -245,7 +245,7 @@ private void gotChannelOpen(SSHPacket buf)
     public void sendOpenFailure(int recipient, Reason reason, String message)
             throws TransportException {
         trans.write(new SSHPacket(Message.CHANNEL_OPEN_FAILURE)
-                            .putUInt32(recipient)
+                            .putUInt32FromInt(recipient)
                             .putUInt32(reason.getCode())
                             .putString(message));
     }

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

@@ -352,7 +352,7 @@ protected void handleRequest(String reqType, SSHPacket buf)
     }
 
     protected SSHPacket newBuffer(Message cmd) {
-        return new SSHPacket(cmd).putUInt32(recipient);
+        return new SSHPacket(cmd).putUInt32FromInt(recipient);
     }
 
     protected void receiveInto(ChannelInputStream stream, SSHPacket buf)

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

@@ -151,7 +151,7 @@ private void checkWindow()
             if (adjustment > 0) {
                 log.debug("Sending SSH_MSG_CHANNEL_WINDOW_ADJUST to #{} for {} bytes", chan.getRecipient(), adjustment);
                 trans.write(new SSHPacket(Message.CHANNEL_WINDOW_ADJUST)
-                        .putUInt32(chan.getRecipient()).putUInt32(adjustment));
+                        .putUInt32FromInt(chan.getRecipient()).putUInt32(adjustment));
                 win.expand(adjustment);
             }
         }

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

@@ -90,7 +90,7 @@ boolean flush(int bufferSize, boolean canAwaitExpansion) throws TransportExcepti
 
                 packet.wpos(headerOffset);
                 packet.putMessageID(Message.CHANNEL_DATA);
-                packet.putUInt32(chan.getRecipient());
+                packet.putUInt32FromInt(chan.getRecipient());
                 packet.putUInt32(writeNow);
                 packet.wpos(dataOffset + writeNow);
 

src/test/java/net/schmizz/sshj/common/BufferTest.java

@@ -25,6 +25,26 @@
 
 public class BufferTest {
 
+    @Test
+    public void testNegativeInteger() throws BufferException {
+        byte[] negativeInt = new byte[] { (byte) 0xB8,
+                (byte) 0x4B,
+                (byte) 0xF4,
+                (byte) 0x38,
+            };
+        PlainBuffer buffer = new PlainBuffer(negativeInt);
+        assertEquals(buffer.readUInt32AsInt(),-1202981832);
+
+        PlainBuffer buff = new PlainBuffer();
+        buff.ensureCapacity(4);
+        buff.putUInt32FromInt(-1202981832);
+        byte[] data = buff.getCompactData();
+        assertEquals(data[0], (byte) 0xB8);
+        assertEquals(data[1], (byte) 0x4B);
+        assertEquals(data[2], (byte) 0xF4);
+        assertEquals(data[3], (byte) 0x38);
+    }
+
     // Issue 72: previously, it entered an infinite loop trying to establish the buffer size
     @Test
     public void shouldThrowOnTooLargeCapacity() {