2 files changed, 14 insertions, 11 deletions

diff --git a/src/main/kotlin/NinePConnection.kt b/src/main/kotlin/NinePConnection.kt
index 535f20e..5a09e8b 100644
--- a/src/main/kotlin/NinePConnection.kt
+++ b/src/main/kotlin/NinePConnection.kt
@@ -21,6 +21,9 @@ class NinePConnection(netPackTrans: NetworkPacketTransporter) : NinePTranslator
      */
     val npt: NetworkPacketTransporter = netPackTrans
 
+    val NOTAG = 0.inv().toUShort()
+
+
     /**
      * Disconnect from the remote host,
      *
@@ -153,26 +156,27 @@ class NinePConnection(netPackTrans: NetworkPacketTransporter) : NinePTranslator
     }
 
     /**
-     * Write a message of the given fields.
+     * Write a message with the given type, tag, and fields. The message size is calculated automatically.
      *
-     * Important note: the field names in [fieldValuesInt] and [fieldValuesStr] (i.e. the keys of their maps) are
-     * mutually exclusive and the union of these two sets must result exactly in the set of field names listed in
+     * Important note: the field names in [fieldValuesInt] and [fieldValuesStr] (i.e. the keys of their maps) must be
+     * mutually exclusive and the union of these two maps' keys must result in a subset of (or a set equal to)
      * [fieldNames].
      *
      * @param type The 9P message type.
+     * @param tag The tag given to the message.
      * @param fieldNames The names of the message fields, in the same order they are expected to be sent.
      * @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.
      * @throws IllegalArgumentException if [fieldNames], [fieldValuesInt], and [fieldValuesStr] are incoherent.
      */
-    private fun writeMessage(type: NinePMessageType, fieldNames: List<String>, fieldValuesInt: Map<String, SizedMessageField>, fieldValuesStr: Map<String, String>) {
+    private fun writeMessage(type: NinePMessageType, tag: UShort, fieldNames: List<String>, fieldValuesInt: Map<String, SizedMessageField>, fieldValuesStr: Map<String, String>) {
         // shorthands
         val insecInts = fieldNames.intersect(fieldValuesInt.keys)
         val insecStrs = fieldNames.intersect(fieldValuesStr.keys)
         // 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 = 4 + 1 + insecInts.sumOf { fieldValuesInt[it]!!.size } + insecStrs.sumOf { 2 + fieldValuesStr[it]!!.length }
+        val totalSize = 4 + 1 + 2 + insecInts.sumOf { fieldValuesInt[it]!!.size } + insecStrs.sumOf { 2 + fieldValuesStr[it]!!.length }
 
         writeMessageSizeType(totalSize, type)
         for (field in fieldNames) {
@@ -184,10 +188,9 @@ class NinePConnection(netPackTrans: NetworkPacketTransporter) : NinePTranslator
         }
     }
 
-    override fun version(tag: SizedMessageField, msize: SizedMessageField, version: String): String? {
-        writeMessage(NinePMessageType.TVERSION, listOf("tag", "msize", "version"),
+    override fun version(msize: SizedMessageField, version: String): String? {
+        writeMessage(NinePMessageType.TVERSION, this.NOTAG, listOf("msize", "version"),
             mapOf(
-                "tag" to tag,
                 "msize" to msize
             ),
             mapOf(
diff --git a/src/main/kotlin/NinePTranslator.kt b/src/main/kotlin/NinePTranslator.kt
index 0bbcb9d..ebb04c5 100644
--- a/src/main/kotlin/NinePTranslator.kt
+++ b/src/main/kotlin/NinePTranslator.kt
@@ -7,6 +7,8 @@ TODO:
  * The [NinePTranslator] interface provides methods that coincide 1:1 with each request and response type in the 9P
  * protocol, except for `Rerror` which is handled at occurrence.
  *
+ * Tags are supposed to be managed internally by the class that provides the implementation.
+ *
  * Trivia: comments for each method are taken from each message type's manual page in section 5.
  */
 interface NinePTranslator {
@@ -15,15 +17,13 @@ interface NinePTranslator {
      *
      * This must be the first message sent on the 9P connection and no other requests can be issued until a response has
      * been received.
-     * Tag should be NOTAG ((ushort)~0).
      *
-     * @param tag Should be NOTAG ((ushort)~0).
      * @param msize The maximum length, in bytes, that the client will ever generate or expect to receive in a single
      *              9P message.
      * @param version Should be "9P2000", which is the only defined value.
      * @return a possible error.
      */
-    fun version(tag: SizedMessageField, msize: SizedMessageField, version: String): String?
+    fun version(msize: SizedMessageField, version: String): String?
 
     /**
      * Perform authentication.