// Tries to grab a file and download it to our local machine
public void GetFile(string filename)
{
// Init the get file state
Console.WriteLine("Requesting file: {0}", filename);
ReceiverState state = ReceiverState.RequestingFile;
byte[] checksum = null;
UInt32 fileSize = 0;
UInt32 numBlocks = 0;
UInt32 totalRequestedBlocks = 0;
Stopwatch transferTimer = new Stopwatch();
// Small function to reset the transfer state
Action ResetTransferState = new Action(() =>
{
state = ReceiverState.RequestingFile;
checksum = null;
fileSize = 0;
numBlocks = 0;
totalRequestedBlocks = 0;
_blockRequestQueue.Clear();
_blocksReceived.Clear();
transferTimer.Reset();
});
// Main loop
_running = true;
bool senderQuit = false;
bool wasRunning = _running;
while (_running)
{
// Check for some new packets (if there are some)
_checkForNetworkMessages();
NetworkMessage nm = (_packetQueue.Count > 0) ? _packetQueue.Dequeue() : null;
// In case the sender is shutdown, quit
bool isBye = (nm == null) ? false : nm.Packet.IsBye;
if (isBye)
{
senderQuit = true;
}
// The state
switch (state)
{
case ReceiverState.RequestingFile:
// Create the REQF
RequestFilePacket REQF = new RequestFilePacket();
REQF.Filename = filename;
// Send it
byte[] buffer = REQF.GetBytes();
_client.Send(buffer, buffer.Length);
// Move the state to waiting for ACK
state = ReceiverState.WaitingForRequestFileACK;
break;
case ReceiverState.WaitingForRequestFileACK:
// If it is an ACK and the payload is the filename, we're good
bool isAck = (nm == null) ? false : (nm.Packet.IsAck);
if (isAck)
{
AckPacket ACK = new AckPacket(nm.Packet);
// Make sure they respond with the filename
if (ACK.Message == filename)
{
// They got it, shift the state
state = ReceiverState.WaitingForInfo;
Console.WriteLine("They have the file, waiting for INFO...");
}
else
{
ResetTransferState(); // Not what we wanted, reset
}
}
break;
case ReceiverState.WaitingForInfo:
// Verify it's file info
bool isInfo = (nm == null) ? false : (nm.Packet.IsInfo);
if (isInfo)
{
// Pull data
InfoPacket INFO = new InfoPacket(nm.Packet);
fileSize = INFO.FileSize;
checksum = INFO.Checksum;
numBlocks = INFO.BlockCount;
// Allocate some client side resources
Console.WriteLine("Received an INFO packet:");
Console.WriteLine(" Max block size: {0}", INFO.MaxBlockSize);
Console.WriteLine(" Num blocks: {0}", INFO.BlockCount);
// Send an ACK for the INFO
AckPacket ACK = new AckPacket();
ACK.Message = "INFO";
buffer = ACK.GetBytes();
_client.Send(buffer, buffer.Length);
// Shift the state to ready
state = ReceiverState.PreparingForTransfer;
}
break;
case ReceiverState.PreparingForTransfer:
// Prepare the request queue
for (UInt32 id = 1; id <= numBlocks; id++)
{
_blockRequestQueue.Enqueue(id);
}
totalRequestedBlocks += numBlocks;
// Shift the state
Console.WriteLine("Starting Transfer...");
transferTimer.Start();
state = ReceiverState.Transfering;
break;
case ReceiverState.Transfering:
// Send a block request
if (_blockRequestQueue.Count > 0)
{
// Setup a request for a Block
UInt32 id = _blockRequestQueue.Dequeue();
RequestBlockPacket REQB = new RequestBlockPacket();
REQB.Number = id;
// Send the Packet
buffer = REQB.GetBytes();
_client.Send(buffer, buffer.Length);
// Some handy info
Console.WriteLine("Sent request for Block #{0}", id);
}
// Check if we have any blocks ourselves in the queue
bool isSend = (nm == null) ? false : (nm.Packet.IsSend);
if (isSend)
{
// Get the data (and save it
SendPacket SEND = new SendPacket(nm.Packet);
Block block = SEND.Block;
_blocksReceived.Add(block.Number, block);
// Print some info
Console.WriteLine("Received Block #{0} [{1} bytes]", block.Number, block.Data.Length);
}
// Requeue any requests that we haven't received
if ((_blockRequestQueue.Count == 0) && (_blocksReceived.Count != numBlocks))
{
for (UInt32 id = 1; id <= numBlocks; id++)
{
if (!_blocksReceived.ContainsKey(id) && !_blockRequestQueue.Contains(id))
{
_blockRequestQueue.Enqueue(id);
totalRequestedBlocks++;
}
}
}
// Did we get all the block we need? Move to the "transfer successful state."
if (_blocksReceived.Count == numBlocks)
{
state = ReceiverState.TransferSuccessful;
}
break;
case ReceiverState.TransferSuccessful:
transferTimer.Stop();
// Things were good, send a BYE message
Packet BYE = new Packet(Packet.Bye);
buffer = BYE.GetBytes();
_client.Send(buffer, buffer.Length);
Console.WriteLine("Transfer successful; it took {0:0.000}s with a success ratio of {1:0.000}.",
transferTimer.Elapsed.TotalSeconds, (double)numBlocks / (double)totalRequestedBlocks);
Console.WriteLine("Decompressing the Blocks...");
// Reconstruct the data
if (_saveBlocksToFile(filename, checksum, fileSize))
{
Console.WriteLine("Saved file as {0}.", filename);
}
else
{
Console.WriteLine("There was some trouble in saving the Blocks to {0}.", filename);
}
// And we're done here
_running = false;
break;
}
// Sleep
Thread.Sleep(1);
// Check for shutdown
_running &= !_shutdownRequested;
_running &= !senderQuit;
}
// Send a BYE message if the user wanted to cancel
if (_shutdownRequested && wasRunning)
{
Console.WriteLine("User canceled transfer.");
Packet BYE = new Packet(Packet.Bye);
byte[] buffer = BYE.GetBytes();
_client.Send(buffer, buffer.Length);
}
// If the server told us to shutdown
if (senderQuit && wasRunning)
{
Console.WriteLine("The sender quit on us, canceling the transfer.");
}
ResetTransferState(); // This also cleans up collections
_shutdownRequested = false; // In case we shut down one download, but want to start a new one
}
// Main loop of the sender
public void Run()
{
// Transfer state
SenderState state = SenderState.WaitingForFileRequest;
string requestedFile = "";
IPEndPoint receiver = null;
// This is a handly little function to reset the transfer state
Action ResetTransferState = new Action(() =>
{
state = SenderState.WaitingForFileRequest;
requestedFile = "";
receiver = null;
_blocks.Clear();
});
while (Running)
{
// Check for some new messages
_checkForNetworkMessages();
NetworkMessage nm = (_packetQueue.Count > 0) ? _packetQueue.Dequeue() : null;
// Check to see if we have a BYE
bool isBye = (nm == null) ? false : nm.Packet.IsBye;
if (isBye)
{
// Set back to the original state
ResetTransferState();
Console.WriteLine("Received a BYE message, waiting for next client.");
}
// Do an action depending on the current state
switch (state)
{
case SenderState.WaitingForFileRequest:
// Check to see that we got a file request
// If there was a packet, and it's a request file, send and ACK and switch the state
bool isRequestFile = (nm == null) ? false : nm.Packet.IsRequestFile;
if (isRequestFile)
{
// Prepare the ACK
RequestFilePacket REQF = new RequestFilePacket(nm.Packet);
AckPacket ACK = new AckPacket();
requestedFile = REQF.Filename;
// Print info
Console.WriteLine("{0} has requested file file \"{1}\".", nm.Sender, requestedFile);
// Check that we have the file
if (_transferableFiles.Contains(requestedFile))
{
// Mark that we have the file, save the sender as our current receiver
receiver = nm.Sender;
ACK.Message = requestedFile;
state = SenderState.PreparingFileForTransfer;
Console.WriteLine(" We have it.");
}
else
{
ResetTransferState();
}
// Send the message
byte[] buffer = ACK.GetBytes();
_client.Send(buffer, buffer.Length, nm.Sender);
}
break;
case SenderState.PreparingFileForTransfer:
// Using the requested file, prepare it in memory
byte[] checksum;
UInt32 fileSize;
if (_prepareFile(requestedFile, out checksum, out fileSize))
{
// It's good, send an info Packet
InfoPacket INFO = new InfoPacket();
INFO.Checksum = checksum;
INFO.FileSize = fileSize;
INFO.MaxBlockSize = MaxBlockSize;
INFO.BlockCount = Convert.ToUInt32(_blocks.Count);
// Send it
byte[] buffer = INFO.GetBytes();
_client.Send(buffer, buffer.Length, receiver);
// Move the state
Console.WriteLine("Sending INFO, waiting for ACK...");
state = SenderState.WaitingForInfoACK;
}
else
{
ResetTransferState(); // File not good, reset the state
}
break;
case SenderState.WaitingForInfoACK:
// If it is an ACK and the payload is the filename, we're good
bool isAck = (nm == null) ? false : (nm.Packet.IsAck);
if (isAck)
{
AckPacket ACK = new AckPacket(nm.Packet);
if (ACK.Message == "INFO")
{
Console.WriteLine("Starting Transfer...");
state = SenderState.Transfering;
}
}
break;
case SenderState.Transfering:
// If there is a block request, send it
bool isRequestBlock = (nm == null) ? false : nm.Packet.IsRequestBlock;
if (isRequestBlock)
{
// Pull out data
RequestBlockPacket REQB = new RequestBlockPacket(nm.Packet);
Console.WriteLine("Got request for Block #{0}", REQB.Number);
// Create the response packet
Block block = _blocks[REQB.Number];
SendPacket SEND = new SendPacket();
SEND.Block = block;
// Send it
byte[] buffer = SEND.GetBytes();
_client.Send(buffer, buffer.Length, nm.Sender);
Console.WriteLine("Sent Block #{0} [{1} bytes]", block.Number, block.Data.Length);
}
break;
}
Thread.Sleep(1);
}
// If there was a receiver set, that means we need to notify it to shutdown
if (receiver != null)
{
Packet BYE = new Packet(Packet.Bye);
byte[] buffer = BYE.GetBytes();
_client.Send(buffer, buffer.Length, receiver);
}
state = SenderState.NotRunning;
}
