chore: follow up for review comments

Author: kruton

sshlib/src/main/kotlin/org/connectbot/sshlib/client/AgentChannel.kt

@@ -91,11 +91,7 @@ internal class AgentChannel(
             while (window.remoteRemaining <= 0) {
                 windowAvailable.receive()
             }
-            val chunkSize = minOf(
-                data.size - offset,
-                window.remoteRemaining.toInt(),
-                maxPacketSize,
-            )
+            val chunkSize = window.sendChunkSize(data.size - offset, maxPacketSize)
             val chunk = data.copyOfRange(offset, offset + chunkSize)
             connection.sendChannelData(remoteChannelNumber, chunk)
             window.consumeRemote(chunkSize)

sshlib/src/main/kotlin/org/connectbot/sshlib/client/ForwardingChannel.kt

@@ -31,11 +31,16 @@ internal class ForwardingChannel(
 ) {
     companion object {
         private val logger = LoggerFactory.getLogger(ForwardingChannel::class.java)
+        private const val WINDOW_ADJUST_THRESHOLD = 64 * 1024
     }
 
     private var _isOpen = true
     private var closeSent = false
-    private val window = LocalChannelWindow(initialWindowSize, remoteInitial = remoteWindowSizeInitial)
+    private val window = LocalChannelWindow(
+        initialWindowSize,
+        adjustThreshold = WINDOW_ADJUST_THRESHOLD,
+        remoteInitial = remoteWindowSizeInitial,
+    )
     private val windowAvailable = Channel<Unit>(Channel.CONFLATED)
 
     private val _incomingData = Channel<ByteArray>(Channel.UNLIMITED)
@@ -85,11 +90,7 @@ internal class ForwardingChannel(
             while (window.remoteRemaining <= 0) {
                 windowAvailable.receive()
             }
-            val chunkSize = minOf(
-                data.size - offset,
-                window.remoteRemaining.toInt(),
-                maxPacketSize,
-            )
+            val chunkSize = window.sendChunkSize(data.size - offset, maxPacketSize)
             val chunk = data.copyOfRange(offset, offset + chunkSize)
             connection.sendChannelData(remoteChannelNumber, chunk)
             window.consumeRemote(chunkSize)

sshlib/src/main/kotlin/org/connectbot/sshlib/client/LocalChannelWindow.kt

@@ -81,4 +81,14 @@ internal class LocalChannelWindow(
     fun consumeRemote(size: Int) {
         remoteRemaining -= size
     }
+
+    /**
+     * Return the next send chunk size without narrowing the uint32 remote
+     * window until it is bounded by Int-sized data and packet limits.
+     */
+    fun sendChunkSize(remainingData: Int, maxPacketSize: Int): Int = minOf(
+        remainingData.toLong(),
+        remoteRemaining,
+        maxPacketSize.toLong(),
+    ).toInt()
 }

sshlib/src/main/kotlin/org/connectbot/sshlib/client/SessionChannel.kt

@@ -151,11 +151,7 @@ class SessionChannel internal constructor(
             while (window.remoteRemaining <= 0) {
                 windowAvailable.receive()
             }
-            val chunkSize = minOf(
-                data.size - offset,
-                window.remoteRemaining.toInt(),
-                maxPacketSize,
-            )
+            val chunkSize = window.sendChunkSize(data.size - offset, maxPacketSize)
             val chunk = data.copyOfRange(offset, offset + chunkSize)
             connection.sendChannelData(_remoteChannelNumber, chunk)
             window.consumeRemote(chunkSize)

sshlib/src/test/kotlin/org/connectbot/sshlib/client/LocalChannelWindowTest.kt

@@ -84,4 +84,11 @@ class LocalChannelWindowTest {
         w.consumeRemote(300)
         assertEquals(700L, w.remoteRemaining)
     }
+
+    @Test
+    fun `sendChunkSize handles uint32 remote window without overflow`() {
+        val w = LocalChannelWindow(initialSize = 1024, remoteInitial = LocalChannelWindow.MAX_WINDOW_SIZE)
+
+        assertEquals(32768, w.sendChunkSize(64 * 1024, 32768))
+    }
 }

sshlib/src/test/kotlin/org/connectbot/sshlib/crypto/DiffieHellmanGroupExchangeTest.kt

@@ -37,9 +37,6 @@ class DiffieHellmanGroupExchangeTest {
     // A tiny 16-bit prime — far below the min=2048 requested by the client
     private val tinyPrime = BigInteger("65537")
 
-    // A 2048-bit composite (GROUP14_P with the last bit flipped) — not a safe prime
-    private val compositeLikePrime = DhGroups.GROUP14_P.subtract(BigInteger.ONE)
-
     @Test
     fun `setGroup rejects p smaller than min bits`() {
         val gex = DiffieHellmanGroupExchange("SHA-256")