add readInteger and readString to NinePConnection

1 files changed, 35 insertions, 0 deletions

diff --git a/src/main/kotlin/NinePConnection.kt b/src/main/kotlin/NinePConnection.kt
index 8514ffd..73ab5fa 100644
--- a/src/main/kotlin/NinePConnection.kt
+++ b/src/main/kotlin/NinePConnection.kt
@@ -1,4 +1,5 @@
 import java.io.IOException
+import java.math.BigInteger
 
 /**
  * This class represents a 9P connection. It provides a practical implementation with networking to the 9P methods
@@ -28,5 +29,39 @@ class NinePConnection(netPackTrans: NetworkPacketTransporter) : NinePTranslator
         this.npt.close()
     }
 
+    /**
+     * Read an [nBytes]-long unsigned integer number from the connection.
+     *
+     * In 9P, binary numbers (non-textual) are specified in little-endian order (least significant byte first).
+     *
+     * @param nBytes The length of the integer number in bytes. It only works with unsigned numbers strictly greater
+     *               than zero (zero is excluded).
+     * @return The number's value.
+     * @throws IllegalArgumentException if [nBytes] is zero or negative.
+     */
+    private fun readInteger(nBytes: Int): BigInteger {
+        require(nBytes > 0)
+        val bytes = this.npt.receiveFixed(nBytes.toULong())
+        var number: BigInteger = BigInteger.valueOf(0)
+        for (i in 0..<bytes.size) {
+            number += bytes[i].toInt().toBigInteger().shl(i)
+        }
+
+        return number
+    }
+
+    /**
+     * Read a string from the connection.
+     *
+     * In 9P, strings are represented as a 2-byte integer (the string's size) followed by the actual UTF-8 string. The
+     * null terminator is forbidden in 9P messages.
+     *
+     * @return The string.
+     */
+    private fun readString(): String {
+        val length = readInteger(2).toInt()
+        return String(this.npt.receiveFixed(length.toULong()).toByteArray())
+    }
+
     // TODO: implement methods from NinePTranslator
 }
\ No newline at end of file