Unbewohnte
3 years ago
10 changed files with 409 additions and 270 deletions
@ -0,0 +1,80 @@
|
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package checksum |
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import ( |
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"crypto/sha256" |
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"fmt" |
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"io" |
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"os" |
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) |
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type CheckSum [32]byte |
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// returns a checksum of given file. NOTE, that it creates checksum
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// not of a full file (from all file bytes), but from separate byte blocks.
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// This is done as an optimisation because the file can be very large in size.
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// The general idea:
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// BOF... CHUNK -> STEP -> CHUNK... EOF
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// checksum := sha256.Sum256(ALLCHUNKS)
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// GetPartialCheckSum is default method used to get a file checksum by sender and receiver
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func GetPartialCheckSum(file *os.File) (CheckSum, error) { |
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// "capturing" CHUNKSIZE bytes and then skipping STEP bytes before the next chunk until the last one
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const CHUNKS uint = 100 |
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const CHUNKSIZE uint = 100 |
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const STEP uint = 250 |
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fileStats, err := file.Stat() |
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if err != nil { |
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return [32]byte{}, fmt.Errorf("could not get the stats: %s", err) |
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} |
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fileSize := fileStats.Size() |
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if fileSize < int64(CHUNKS*CHUNKSIZE+STEP*(CHUNKS-1)) { |
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// file is too small, doing full checksum
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checksum, err := getFullCheckSum(file) |
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if err != nil { |
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return [32]byte{}, err |
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} |
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return checksum, nil |
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} |
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var capturedChunks string |
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var read uint64 = 0 |
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for i := 0; uint(i) < CHUNKS; i++ { |
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buffer := make([]byte, CHUNKSIZE) |
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r, _ := file.ReadAt(buffer, int64(read)) |
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capturedChunks += string(buffer) |
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read += uint64(r) |
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read += uint64(STEP) |
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} |
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checksum := sha256.Sum256([]byte(capturedChunks)) |
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return checksum, nil |
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} |
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// returns a sha256 checksum of given file
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func getFullCheckSum(file *os.File) (CheckSum, error) { |
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filebytes, err := io.ReadAll(file) |
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if err != nil { |
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return [32]byte{}, fmt.Errorf("could not read the file: %s", err) |
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} |
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checksum := sha256.Sum256(filebytes) |
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return checksum, nil |
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} |
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// simply compares 2 given checksums. If they are equal - returns true
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func AreEqual(checksum1, checksum2 CheckSum) bool { |
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var i int = 0 |
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for _, checksum1Byte := range checksum1 { |
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checksum2Byte := checksum2[i] |
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if checksum1Byte != checksum2Byte { |
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return false |
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} |
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i++ |
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} |
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return true |
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} |
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@ -1,198 +0,0 @@
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package client |
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import ( |
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"fmt" |
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"net" |
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"os" |
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"path/filepath" |
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"strings" |
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"github.com/Unbewohnte/FTU/protocol" |
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) |
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// Representation of a tcp client
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type Client struct { |
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DownloadsFolder string |
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Connection net.Conn |
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IncomingPackets chan protocol.Packet |
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Stopped bool |
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ReadyToReceive bool |
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PacketCounter uint64 |
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} |
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// Creates a new client with default fields
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func NewClient(downloadsFolder string) *Client { |
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os.MkdirAll(downloadsFolder, os.ModePerm) |
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info, err := os.Stat(downloadsFolder) |
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if err != nil { |
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panic(err) |
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} |
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if !info.IsDir() { |
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panic("Downloads folder is not a directory") |
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} |
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incomingPacketsChan := make(chan protocol.Packet, 5) |
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var PacketCounter uint64 = 0 |
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fmt.Println("Created a new client") |
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return &Client{ |
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DownloadsFolder: downloadsFolder, |
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Connection: nil, |
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IncomingPackets: incomingPacketsChan, |
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Stopped: false, |
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ReadyToReceive: false, |
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PacketCounter: PacketCounter, |
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} |
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} |
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// Closes the connection
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func (c *Client) Disconnect() { |
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c.Connection.Close() |
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} |
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// Closes the connection, warns the server and exits the mainloop
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func (c *Client) Stop() { |
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disconnectionPacket := protocol.Packet{ |
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Header: protocol.HeaderDisconnecting, |
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} |
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protocol.SendPacket(c.Connection, disconnectionPacket) |
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c.Stopped = true |
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c.Disconnect() |
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} |
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// Connects to a given address over tcp. Sets a connection to a client
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func (c *Client) Connect(addr string) error { |
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fmt.Printf("Trying to connect to %s...\n", addr) |
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connection, err := net.Dial("tcp", addr) |
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if err != nil { |
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return fmt.Errorf("could not connect to %s: %s", addr, err) |
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} |
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c.Connection = connection |
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fmt.Println("Connected to ", c.Connection.RemoteAddr()) |
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return nil |
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} |
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// Handles the fileinfo packet. The choice of acceptance is given to the user
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func (c *Client) HandleFileOffer(fileinfoPacket protocol.Packet) error { |
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// inform the user about the file
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fmt.Printf("Incoming fileinfo packet:\nFilename: %s\nFilesize: %.3fMB\nAccept ? [Y/N]: ", |
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fileinfoPacket.Filename, float32(fileinfoPacket.Filesize)/1024/1024) |
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// get and process the input
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var input string |
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fmt.Scanln(&input) |
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input = strings.TrimSpace(input) |
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input = strings.ToLower(input) |
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// reject the file
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if input != "y" { |
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rejectionPacket := protocol.Packet{ |
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Header: protocol.HeaderReject, |
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} |
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err := protocol.SendPacket(c.Connection, rejectionPacket) |
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if err != nil { |
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return fmt.Errorf("could not send a rejection packet: %s", err) |
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} |
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c.ReadyToReceive = false |
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return nil |
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} |
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// accept the file
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acceptancePacket := protocol.Packet{ |
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Header: protocol.HeaderAccept, |
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} |
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err := protocol.SendPacket(c.Connection, acceptancePacket) |
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if err != nil { |
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return fmt.Errorf("could not send an acceptance packet: %s", err) |
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} |
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// can and ready to receive file packets
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c.ReadyToReceive = true |
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return nil |
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} |
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// Handles the download by writing incoming bytes into the file
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func (c *Client) WritePieceOfFile(filePacket protocol.Packet) error { |
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c.ReadyToReceive = false |
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// open|create a file with the same name as the filepacket`s file name
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file, err := os.OpenFile(filepath.Join(c.DownloadsFolder, filePacket.Filename), os.O_CREATE|os.O_APPEND|os.O_WRONLY, os.ModePerm) |
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if err != nil { |
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return err |
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} |
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// just write the filedata
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file.Write(filePacket.FileData) |
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file.Close() |
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c.PacketCounter++ |
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c.ReadyToReceive = true |
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return nil |
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} |
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// Listens in an endless loop; reads incoming packages and puts them into channel
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func (c *Client) ReceivePackets() { |
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for { |
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incomingPacket, err := protocol.ReadFromConn(c.Connection) |
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if err != nil { |
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// in current implementation there is no way to receive a working file even if only one packet is missing
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fmt.Printf("Error reading a packet: %s\nExiting...", err) |
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os.Exit(-1) |
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} |
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c.IncomingPackets <- incomingPacket |
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} |
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} |
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// The "head" of the client. Similarly as in server`s logic "glues" everything together.
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// Current structure allows the client to receive any type of packet
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// in any order and react correspondingly
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func (c *Client) MainLoop() { |
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go c.ReceivePackets() |
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for { |
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if c.Stopped { |
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// exit the mainloop
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break |
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} |
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// 1) send -> 2) handle received if necessary
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// send a packet telling server to send another piece of file
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if c.ReadyToReceive { |
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readyPacket := protocol.Packet{ |
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Header: protocol.HeaderReady, |
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} |
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protocol.SendPacket(c.Connection, readyPacket) |
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c.ReadyToReceive = false |
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} |
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// no incoming packets ? Skipping the packet handling part
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if len(c.IncomingPackets) == 0 { |
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continue |
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} |
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// take the packet and handle depending on the header
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incomingPacket := <-c.IncomingPackets |
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// handling each packet header differently
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switch incomingPacket.Header { |
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case protocol.HeaderFileInfo: |
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go c.HandleFileOffer(incomingPacket) |
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case protocol.HeaderFileData: |
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go c.WritePieceOfFile(incomingPacket) |
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case protocol.HeaderDisconnecting: |
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// the server is ded, no need to stay alive as well
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fmt.Println("Done. Got ", c.PacketCounter, " packets in total") |
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c.Stopped = true |
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c.Stop() |
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} |
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} |
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} |
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@ -0,0 +1,10 @@
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package receiver |
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import "github.com/Unbewohnte/FTU/checksum" |
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// Receiver`s file struct. Used internally by receiver
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type File struct { |
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Filename string |
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Filesize uint64 |
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CheckSum checksum.CheckSum |
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} |
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@ -0,0 +1,233 @@
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package receiver |
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import ( |
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"fmt" |
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"net" |
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"os" |
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"path/filepath" |
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"strings" |
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|
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"github.com/Unbewohnte/FTU/checksum" |
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"github.com/Unbewohnte/FTU/protocol" |
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) |
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// Representation of a receiver
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type Receiver struct { |
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DownloadsFolder string |
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Connection net.Conn |
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IncomingPackets chan protocol.Packet |
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FileToDownload *File |
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Stopped bool |
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ReadyToReceive bool |
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PacketCounter uint64 |
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} |
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// Creates a new client with default fields
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func NewReceiver(downloadsFolder string) *Receiver { |
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os.MkdirAll(downloadsFolder, os.ModePerm) |
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downloadsFolderInfo, err := os.Stat(downloadsFolder) |
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if err != nil { |
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panic(err) |
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} |
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if !downloadsFolderInfo.IsDir() { |
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panic("Downloads folder is not a directory") |
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} |
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incomingPacketsChan := make(chan protocol.Packet, 5) |
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var PacketCounter uint64 = 0 |
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fmt.Println("Created a new client") |
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return &Receiver{ |
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DownloadsFolder: downloadsFolder, |
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Connection: nil, |
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IncomingPackets: incomingPacketsChan, |
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Stopped: false, |
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ReadyToReceive: false, |
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PacketCounter: PacketCounter, |
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} |
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} |
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// Closes the connection
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func (r *Receiver) Disconnect() { |
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r.Connection.Close() |
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} |
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// Closes the connection, warns the sender and exits the mainloop
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func (r *Receiver) Stop() { |
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disconnectionPacket := protocol.Packet{ |
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Header: protocol.HeaderDisconnecting, |
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} |
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protocol.SendPacket(r.Connection, disconnectionPacket) |
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r.Stopped = true |
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r.Disconnect() |
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} |
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|
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// Connects to a given address over tcp. Sets a connection to a corresponding field in receiver
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func (r *Receiver) Connect(addr string) error { |
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fmt.Printf("Trying to connect to %s...\n", addr) |
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connection, err := net.Dial("tcp", addr) |
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if err != nil { |
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return fmt.Errorf("could not connect to %s: %s", addr, err) |
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} |
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r.Connection = connection |
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fmt.Println("Connected to ", r.Connection.RemoteAddr()) |
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return nil |
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} |
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// Handles the fileinfo packet. The choice of acceptance is given to the user
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func (r *Receiver) HandleFileOffer(fileinfoPacket protocol.Packet) error { |
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// inform the user about the file
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// fmt.Printf("Incoming fileinfo packet:\nFilename: %s\nFilesize: %.3fMB\nCheckSum: %s\nAccept ? [Y/N]: ",
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// fileinfoPacket.Filename, float32(fileinfoPacket.Filesize)/1024/1024, fileinfoPacket.FileCheckSum)
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fmt.Printf(` |
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Incoming fileinfo packet: |
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| Filename: %s |
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| Filesize: %.3fMB |
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| Checksum: %x |
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|
|
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| Download ? [Y/N]: `, |
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fileinfoPacket.Filename, float32(fileinfoPacket.Filesize)/1024/1024, fileinfoPacket.FileCheckSum, |
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) |
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// get and process the input
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var input string |
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fmt.Scanln(&input) |
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input = strings.TrimSpace(input) |
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input = strings.ToLower(input) |
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// reject the file
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if input != "y" { |
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rejectionPacket := protocol.Packet{ |
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Header: protocol.HeaderReject, |
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} |
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err := protocol.SendPacket(r.Connection, rejectionPacket) |
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if err != nil { |
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return fmt.Errorf("could not send a rejection packet: %s", err) |
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} |
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r.ReadyToReceive = false |
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return nil |
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} |
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// accept the file
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r.FileToDownload = &File{ |
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Filename: fileinfoPacket.Filename, |
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Filesize: fileinfoPacket.Filesize, |
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CheckSum: fileinfoPacket.FileCheckSum, |
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} |
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acceptancePacket := protocol.Packet{ |
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Header: protocol.HeaderAccept, |
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} |
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err := protocol.SendPacket(r.Connection, acceptancePacket) |
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if err != nil { |
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return fmt.Errorf("could not send an acceptance packet: %s", err) |
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} |
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// can and ready to receive file packets
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r.ReadyToReceive = true |
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return nil |
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} |
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|
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// Handles the download by writing incoming bytes into the file
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func (r *Receiver) WritePieceOfFile(filePacket protocol.Packet) error { |
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r.ReadyToReceive = false |
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|
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// open|create a file with the same name as the filepacket`s file name
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file, err := os.OpenFile(filepath.Join(r.DownloadsFolder, filePacket.Filename), os.O_CREATE|os.O_APPEND|os.O_WRONLY, os.ModePerm) |
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if err != nil { |
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return err |
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} |
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// just write the filedata
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file.Write(filePacket.FileData) |
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file.Close() |
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r.PacketCounter++ |
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r.ReadyToReceive = true |
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return nil |
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} |
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|
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// Listens in an endless loop; reads incoming packages and puts them into channel
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func (r *Receiver) ReceivePackets() { |
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for { |
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incomingPacket, err := protocol.ReadFromConn(r.Connection) |
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if err != nil { |
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// in current implementation there is no way to receive a working file even if only one packet is missing
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fmt.Printf("Error reading a packet: %s\nExiting...", err) |
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os.Exit(-1) |
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} |
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r.IncomingPackets <- incomingPacket |
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} |
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} |
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|
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// The "head" of the receiver. Similarly as in server`s logic "glues" everything together.
|
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// Current structure allows the receiver to receive any type of packet
|
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// in any order and react correspondingly
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func (r *Receiver) MainLoop() { |
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go r.ReceivePackets() |
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for { |
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if r.Stopped { |
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// exit the mainloop
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break |
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} |
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|
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// send a packet telling sender to send another piece of file
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if r.ReadyToReceive { |
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readyPacket := protocol.Packet{ |
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Header: protocol.HeaderReady, |
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} |
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protocol.SendPacket(r.Connection, readyPacket) |
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r.ReadyToReceive = false |
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} |
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|
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// no incoming packets ? Skipping the packet handling part
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if len(r.IncomingPackets) == 0 { |
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continue |
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} |
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|
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// take the packet and handle depending on the header
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incomingPacket := <-r.IncomingPackets |
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|
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// handling each packet header differently
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switch incomingPacket.Header { |
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|
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case protocol.HeaderFileInfo: |
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go r.HandleFileOffer(incomingPacket) |
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|
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case protocol.HeaderFileData: |
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go r.WritePieceOfFile(incomingPacket) |
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|
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case protocol.HeaderDisconnecting: |
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// the sender has completed its mission,
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// checking hashes and exiting
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|
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fmt.Println("Got ", r.PacketCounter, " packets in total") |
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fmt.Println("Checking checksums...") |
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|
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file, err := os.Open(filepath.Join(r.DownloadsFolder, r.FileToDownload.Filename)) |
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if err != nil { |
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fmt.Printf("error while opening downloaded file for checking: %s\n", err) |
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os.Exit(-1) |
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} |
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realCheckSum, err := checksum.GetPartialCheckSum(file) |
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if err != nil { |
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fmt.Printf("error perfoming partial checksum: %s\n", err) |
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os.Exit(-1) |
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} |
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|
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fmt.Printf("\n%x ----- %x\n", r.FileToDownload.CheckSum, realCheckSum) |
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if !checksum.AreEqual(realCheckSum, r.FileToDownload.CheckSum) { |
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fmt.Println("Downloaded file is corrupted !") |
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} |
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r.Stop() |
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} |
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} |
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} |
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