A simple TFTP client using C++

Introduction

TFTP stands for Trivial File Transfer Protocol. It is still used today for transferring new firmware to routers and other embedded devices, and also for booting network terminals. For a detailed description, see RFC 1350.

Looking for a simple C++ implementation of this protocol, I couldn't find one. So, I had to write it. Hope this code will save some time for someone.

Using the Code

Initialization
The client uses the Winsock library, so you have to initialize it manually before using the code, or use the static function CTFTPClient::Startup.
```
CTFTPClient::Startup();
```
or
```
WSADATA w;
WSAStartup(0x0101, &w);
```
Creation
Create the TFTP client object.
```
CTFTPClient* c = new CTFTPClient();
```
Transfer
Use the Get and Put functions to start the file transfer. When successful, it returns the TFTP_RESULT_CONTINUE value. Then, you have to call the Continue function to transfer another packet, till it returns TFTP_RESULT_DONE. Transferring the process can be controlled by reading the number of bytes and packets using the functions PacketsCount and BytesCount.
```
// Sending file
int rc = c->Put("c:\\123.txt","123.txt","127.0.0.1");
while (rc==TFTP_RESULT_CONTINUE) rc = c->Continue();
```
```
// Receiving file
rc = c->Get("c:\\321.txt","123.txt","127.0.0.1");
while (rc==TFTP_RESULT_CONTINUE) rc = c->Continue();
```
If TFTP_RESULT_ERROR was returned by Get, Put, or Continue, use LastError to see what happens. See the demo project main function for a more detailed example.
Cleanup
Delete the TFTP client object and free the Winsock library.
```
delete c;
CTFTPClient::Cleanup();
```
or
```
delete c;
WSACleanup();
```