change version to use exceptions instead of error strings

2 files changed, 10 insertions, 13 deletions

diff --git a/src/main/kotlin/Connection.kt b/src/main/kotlin/Connection.kt
index 48394e0..a0923e8 100644
--- a/src/main/kotlin/Connection.kt
+++ b/src/main/kotlin/Connection.kt
@@ -72,7 +72,7 @@ class Connection(transLay: TransportLayer) : ProtocolTranslator {
         return imsg
     }
 
-    override fun version(msize: UInt, version: String): String? {
+    override fun version(msize: UInt, version: String) {
         val omsg = OutMessage(NinePMessageType.TVERSION, this.NOTAG, listOf("msize", "version"),
             mapOf(
                 "msize" to BigInteger(msize.toString())
@@ -84,25 +84,19 @@ class Connection(transLay: TransportLayer) : ProtocolTranslator {
             this.maxSize
         )
         omsg.write(this.tl)
-        val imsg: InMessage
-        try {
-            imsg = InMessage(this.tl, msize, omsg.tag)
-        } catch (ime: InvalidMessageException) {
-            return ime.message
-        }
+        val imsg = checkedInMessage(omsg.tag)
         imsg.applySchema(listOf(
             InMessage.Field("msize", InMessage.Field.Type.INTEGER, 4u),
             InMessage.Field("version", InMessage.Field.Type.STRING, 0u)
         ))
         val remoteMaxSize = imsg.fieldsInt["msize"]!!.toInt().toUInt()
         if (remoteMaxSize > this.maxSize) {
-            return "Invalid remote msize value (too big)."
+            throw MsizeValueTooBigException(msize, remoteMaxSize)
         }
         this.maxSize = remoteMaxSize
-        if (imsg.fieldsStr["version"] == "unknown") {
-            return "Unknown version."
+        if (!imsg.fieldsStr["version"]!!.startsWith("9P2000")) {
+            throw UnknownVersionException(imsg.fieldsStr["version"]!!)
         }
-        return null
     }
 
     override fun auth(afid: UInt, uname: String, aname: String) {
diff --git a/src/main/kotlin/ProtocolTranslator.kt b/src/main/kotlin/ProtocolTranslator.kt
index eaa415f..f7b114f 100644
--- a/src/main/kotlin/ProtocolTranslator.kt
+++ b/src/main/kotlin/ProtocolTranslator.kt
@@ -27,9 +27,12 @@ interface ProtocolTranslator {
      * @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.
+     * @throws InvalidMessageException if the received message is invalid.
+     * @throws RErrorException if the received message is an R-error message.
+     * @throws MsizeValueTooBigException if the received `msize` value is bigger than what the client requested.
+     * @throws UnknownVersionException if the version negotiation failed.
      */
-    fun version(msize: UInt, version: String): String?
+    fun version(msize: UInt, version: String)
 
     /**
      * Perform authentication.