enforce msize observance

2 files changed, 15 insertions, 6 deletions

diff --git a/src/main/kotlin/NinePConnection.kt b/src/main/kotlin/NinePConnection.kt
index 6f678a0..5adb35b 100644
--- a/src/main/kotlin/NinePConnection.kt
+++ b/src/main/kotlin/NinePConnection.kt
@@ -127,10 +127,14 @@ class NinePConnection(netPackTrans: NetworkPacketTransporter) : NinePTranslator
     }
 
     /**
-     * Send 9P request and check for Rerror response.
+     * Send 9P request and check for exceptions or a Rerror response.
      */
     private fun responseError(msg: NinePMessage): String? {
-        msg.write(this.npt)
+        try {
+            msg.write(this.npt)
+        } catch (ex: Exception) {
+            return "Exception thrown while sending message: (" + ex.javaClass.toString() + ") " + ex.message
+        }
         val se = waitForTag(msg.tag)
         if (se.second == NinePMessageType.RERROR) {
             val error = readError()
@@ -146,7 +150,8 @@ class NinePConnection(netPackTrans: NetworkPacketTransporter) : NinePTranslator
             ),
             mapOf(
                 "version" to version
-            )
+            ),
+            this.maxSize
         )
         val error = responseError(msg)
         if (error != null) {
@@ -157,7 +162,7 @@ class NinePConnection(netPackTrans: NetworkPacketTransporter) : NinePTranslator
         // this check should not be necessary, but you never know
         this.maxSize = ( if (rmsize < msize.value) msize.value else rmsize ).toInt().toUInt()
         if (rversion == "unknown") {
-            return "Unknown version"
+            return "Unknown version."
         }
         return null
     }
diff --git a/src/main/kotlin/NinePMessage.kt b/src/main/kotlin/NinePMessage.kt
index 1d0530a..87d59a5 100644
--- a/src/main/kotlin/NinePMessage.kt
+++ b/src/main/kotlin/NinePMessage.kt
@@ -13,7 +13,7 @@ import kotlin.math.pow
  * @param fieldValuesInt A map of each field name into its value. This map only stores integer values.
  * @param fieldValuesStr A map of each field name into its value. This map only stores string values.
  */
-class NinePMessage(val type: NinePMessageType, val tag: UShort, val fieldNames: List<String>, val fieldValuesInt: Map<String, SizedMessageField>, val fieldValuesStr: Map<String, String>) {
+class NinePMessage(val type: NinePMessageType, val tag: UShort, val fieldNames: List<String>, val fieldValuesInt: Map<String, SizedMessageField>, val fieldValuesStr: Map<String, String>, val maxSize: UInt) {
     /**
      * Intersection between [fieldNames] and [fieldValuesInt]. In other words: the amount of integer fields that are
      * going to be used when writing the message.
@@ -29,13 +29,17 @@ class NinePMessage(val type: NinePMessageType, val tag: UShort, val fieldNames:
      * Send the message using the given networking API.
      *
      * @param npt The networking API.
-     * @throws IllegalArgumentException if [fieldNames], [fieldValuesInt], and [fieldValuesStr] are incoherent.
+     * @throws IllegalArgumentException if [fieldNames], [fieldValuesInt], and [fieldValuesStr] are incoherent or the
+     *         final size of the message exceeds the negotiated value.
      */
     fun write(npt: NetworkPacketTransporter) {
         // check that names in fieldNames exist as keys in either fieldValuesInt or fieldValuesStr but not both
         require(insecInts.size == fieldNames.size - insecStrs.size)
 
         val totalSize = size()
+        if (totalSize > this.maxSize.toLong()) {
+            throw IllegalArgumentException("Message size exceeded.")
+        }
         writeMessageSizeType(npt, totalSize, type)
         writeInteger(npt, SizedMessageField(2, tag.toInt().toBigInteger()))
         for (field in fieldNames) {