diff --git a/t/test.py b/t/test.py
index 1052db1..d044ac8 100644
--- a/t/test.py
+++ b/t/test.py
@@ -4,6 +4,7 @@ import unittest
 import logging
 import tftpy
 import os
+import time
 
 log = tftpy.log
 
@@ -140,6 +141,72 @@ class TestTftpyState(unittest.TestCase):
     def setUp(self):
         tftpy.setLogLevel(logging.DEBUG)
 
+    def clientServerUploadOptions(self, options):
+        """Fire up a client and a server and do an upload."""
+        root = '/tmp'
+        home = os.path.dirname(os.path.abspath(__file__))
+        filename = '100KBFILE'
+        input_path = os.path.join(home, filename)
+        server = tftpy.TftpServer(root)
+        client = tftpy.TftpClient('localhost',
+                                  20001,
+                                  options)
+        # Fork a server and run the client in this process.
+        child_pid = os.fork()
+        if child_pid:
+            # parent - let the server start
+            try:
+                time.sleep(1)
+                client.upload(filename,
+                              input_path)
+            finally:
+                os.kill(child_pid, 15)
+                os.waitpid(child_pid, 0)
+
+        else:
+            server.listen('localhost', 20001)
+
+    def clientServerDownloadOptions(self, options):
+        """Fire up a client and a server and do a download."""
+        root = os.path.dirname(os.path.abspath(__file__))
+        server = tftpy.TftpServer(root)
+        client = tftpy.TftpClient('localhost',
+                                  20001,
+                                  options)
+        # Fork a server and run the client in this process.
+        child_pid = os.fork()
+        if child_pid:
+            # parent - let the server start
+            try:
+                time.sleep(1)
+                client.download('100KBFILE',
+                                '/tmp/out')
+            finally:
+                os.kill(child_pid, 15)
+                os.waitpid(child_pid, 0)
+
+        else:
+            server.listen('localhost', 20001)
+
+    def testClientServerNoOptions(self):
+        self.clientServerDownloadOptions({})
+
+    def testClientServerBlksize(self):
+        for blksize in [512, 1024, 2048, 4096]:
+            self.clientServerDownloadOptions({'blksize': blksize})
+
+    def testClientServerUploadNoOptions(self):
+        self.clientServerUploadOptions({})
+
+    def testClientServerUploadOptions(self):
+        for blksize in [512, 1024, 2048, 4096]:
+            self.clientServerUploadOptions({'blksize': blksize})
+
+    def testClientServerNoOptionsDelay(self):
+        tftpy.TftpStates.DELAY_BLOCK = 10
+        self.clientServerDownloadOptions({})
+        tftpy.TftpStates.DELAY_BLOCK = 0
+
     def testServerNoOptions(self):
         """Test the server states."""
         raddress = '127.0.0.2'
diff --git a/tftpy/TftpClient.py b/tftpy/TftpClient.py
index 16753f1..e9e46e7 100644
--- a/tftpy/TftpClient.py
+++ b/tftpy/TftpClient.py
@@ -74,10 +74,10 @@ class TftpClient(TftpSession):
         setting, which is the amount of time that the client will wait for a
         DAT packet to be ACKd by the server.
 
+        The input option is the full path to the file to upload, which can
+        optionally be '-' to read from stdin.
+
         Note: If output is a hyphen then stdout is used."""
-        # Open the input file.
-        # FIXME: As of the state machine, this is now broken. Need to
-        # implement with new state machine.
         self.context = TftpContextClientUpload(self.host,
                                                  self.iport,
                                                  filename,
diff --git a/tftpy/TftpContexts.py b/tftpy/TftpContexts.py
index a76b686..c3a1bd4 100644
--- a/tftpy/TftpContexts.py
+++ b/tftpy/TftpContexts.py
@@ -50,15 +50,15 @@ class TftpMetrics(object):
         for key in self.dups:
             self.dupcount += self.dups[key]
 
-    def add_dup(self, blocknumber):
-        """This method adds a dup for a block number to the metrics."""
-        log.debug("Recording a dup for block %d" % blocknumber)
-        if self.dups.has_key(blocknumber):
-            self.dups[blocknumber] += 1
+    def add_dup(self, pkt):
+        """This method adds a dup for a packet to the metrics."""
+        log.debug("Recording a dup of %s" % pkt)
+        s = str(pkt)
+        if self.dups.has_key(s):
+            self.dups[s] += 1
         else:
-            self.dups[blocknumber] = 1
-        tftpassert(self.dups[blocknumber] < MAX_DUPS,
-            "Max duplicates for block %d reached" % blocknumber)
+            self.dups[s] = 1
+        tftpassert(self.dups[s] < MAX_DUPS, "Max duplicates reached")
 
 ###############################################################################
 # Context classes
diff --git a/tftpy/TftpShared.py b/tftpy/TftpShared.py
index 1039ed2..d09d8bd 100644
--- a/tftpy/TftpShared.py
+++ b/tftpy/TftpShared.py
@@ -11,6 +11,9 @@ MAX_DUPS = 20
 TIMEOUT_RETRIES = 5
 DEF_TFTP_PORT = 69
 
+# A hook for deliberately introducing delay in testing.
+DELAY_BLOCK = 0
+
 # Initialize the logger.
 logging.basicConfig()
 # The logger used by this library. Feel free to clobber it with your own, if you like, as
diff --git a/tftpy/TftpStates.py b/tftpy/TftpStates.py
index 716220a..c106220 100644
--- a/tftpy/TftpStates.py
+++ b/tftpy/TftpStates.py
@@ -124,30 +124,29 @@ class TftpState(object):
 
         return sendoack
 
-    def sendDAT(self, resend=False):
+    def sendDAT(self):
         """This method sends the next DAT packet based on the data in the
         context. It returns a boolean indicating whether the transfer is
         finished."""
         finished = False
         blocknumber = self.context.next_block
+        # Test hook
+        if DELAY_BLOCK and DELAY_BLOCK == blocknumber:
+            import time
+            log.debug("Deliberately delaying 10 seconds...")
+            time.sleep(10)
         tftpassert( blocknumber > 0, "There is no block zero!" )
         dat = None
-        if resend:
-            log.warn("Resending block number %d" % blocknumber)
-            dat = self.context.last_pkt
-            self.context.metrics.resent_bytes += len(dat.data)
-            self.context.metrics.add_dup(dat)
-        else:
-            blksize = self.context.getBlocksize()
-            buffer = self.context.fileobj.read(blksize)
-            log.debug("Read %d bytes into buffer" % len(buffer))
-            if len(buffer) < blksize:
-                log.info("Reached EOF on file %s"
-                    % self.context.file_to_transfer)
-                finished = True
-            dat = TftpPacketDAT()
-            dat.data = buffer
-            dat.blocknumber = blocknumber
+        blksize = self.context.getBlocksize()
+        buffer = self.context.fileobj.read(blksize)
+        log.debug("Read %d bytes into buffer" % len(buffer))
+        if len(buffer) < blksize:
+            log.info("Reached EOF on file %s"
+                % self.context.file_to_transfer)
+            finished = True
+        dat = TftpPacketDAT()
+        dat.data = buffer
+        dat.blocknumber = blocknumber
         self.context.metrics.bytes += len(dat.data)
         log.debug("Sending DAT packet %d" % dat.blocknumber)
         self.context.sock.sendto(dat.encode().buffer,
@@ -170,7 +169,7 @@ class TftpState(object):
         self.context.sock.sendto(ackpkt.encode().buffer,
                                  (self.context.host,
                                   self.context.tidport))
-        self.last_pkt = ackpkt
+        self.context.last_pkt = ackpkt
 
     def sendError(self, errorcode):
         """This method uses the socket passed, and uses the errorcode to
@@ -181,7 +180,7 @@ class TftpState(object):
         self.context.sock.sendto(errpkt.encode().buffer,
                                  (self.context.host,
                                   self.context.tidport))
-        self.last_pkt = errpkt
+        self.context.last_pkt = errpkt
 
     def sendOACK(self):
         """This method sends an OACK packet with the options from the current
@@ -192,18 +191,18 @@ class TftpState(object):
         self.context.sock.sendto(pkt.encode().buffer,
                                  (self.context.host,
                                   self.context.tidport))
-        self.last_pkt = pkt
+        self.context.last_pkt = pkt
 
     def resendLast(self):
         "Resend the last sent packet due to a timeout."
         log.warn("Resending packet %s on sessions %s"
-            % (self.last_pkt, self))
-        self.context.metrics.resent_bytes += len(self.last_pkt.data)
-        self.context.metrics.add_dup(self.last_pkt)
-        self.context.sock.sendto(self.last_pkt.encode().buffer,
+            % (self.context.last_pkt, self))
+        self.context.metrics.resent_bytes += len(self.context.last_pkt.buffer)
+        self.context.metrics.add_dup(self.context.last_pkt)
+        self.context.sock.sendto(self.context.last_pkt.encode().buffer,
                                  (self.context.host, self.context.tidport))
         if self.context.packethook:
-            self.context.packethook(self.last_pkt)
+            self.context.packethook(self.context.last_pkt)
 
     def handleDat(self, pkt):
         """This method handles a DAT packet during a client download, or a
@@ -232,7 +231,7 @@ class TftpState(object):
                 self.sendError(TftpErrors.IllegalTftpOp)
                 raise TftpException, "There is no block zero!"
             log.warn("Dropping duplicate block %d" % pkt.blocknumber)
-            self.context.metrics.add_dup(pkt.blocknumber)
+            self.context.metrics.add_dup(pkt)
             log.debug("ACKing block %d again, just in case" % pkt.blocknumber)
             self.sendACK(pkt.blocknumber)
 
@@ -369,7 +368,9 @@ class TftpStateExpectACK(TftpState):
                     self.context.pending_complete = self.sendDAT()
 
             elif pkt.blocknumber < self.context.next_block:
-                self.context.metrics.add_dup(pkt.blocknumber)
+                log.debug("Received duplicate ACK for block %d"
+                    % pkt.blocknumber)
+                self.context.metrics.add_dup(pkt)
 
             else:
                 log.warn("Oooh, time warp. Received ACK to packet we "