custom ftp server

[stone trellis]

So, i am creating a FTP server, that works with a SERVER.java and Client.java..
When a client connects to the server, the server first reads a one-line command from the client.
The command can be:
• The string "LIST". In this case, the server responds by sending a list of names of all the
files that are available on the server.
• Or the command can be of the form "GET <filename>", where <filename> is a file name.
o The server checks whether the requested file exists.
o If so, it sends "OK" as a message to the client. Then it sends the contents of the
file and closes the connection.
o Otherwise, it sends a line beginning with the word "ERROR" to the client.
• The server can also respond with the message "unknown command" if the command it
reads is not one of the two possible legal commands,
For all the three cases, the server must return a thread ID (worker ID) to the client.
Your program should use a thread class to handle each request that the server receives. It should
not stop after handling one request; it should remain open and continue to accept new requests.

I am done with all this cases, but when I am typing GET Command in terminal my terminal get stucks...

This is the SERVER.java output

PS D:\Assignmensts\assignment 2> java -jar Server.jar
Server is listening on port 7210
Received command: LIST
Sent LIST response
Received command: LIST
Sent LIST response
Received command: GET test.txt
Sent OK response for file: test.txt

and This is the output of client.java

PS D:\Assignmensts\assignment 2> java Client 127.0.0.1 7210
Connecting to server 127.0.0.1:7210
---Connection Successful---
Received Worker ID: 21
Enter command (type 'exit' to close connection): LIST
Sending "LIST" to server
Server response:
test.txt
Enter command (type 'exit' to close connection): LIST
Sending "LIST" to server
Server response:
test.txt
Enter command (type 'exit' to close connection): GET test.txt 
Sending "GET test.txt" to server
File "test.txt" already exists. Do you want to overwrite it? (yes/no): yes

Here, after the File "test.txt" already exists. Do you want to overwrite it? (yes/no): yes line my terminal get stucks but the expected output is Download Successful...

i dont know, what part of my code is giving the issue, kindly help me please i request i am trying to fix from 4-5 hours... waiting for the response.

[grave reef]

<@&987246883653156906> please have a look, thanks.

[stone trellis]

should i upload full code??

[grave reef]

custom ftp server

Changed the title to custom ftp server.

[frozen shuttle]

would be helpful. otherwise i dont see how anyone could really help

[stone trellis]

okay wait i will paste the code

This are the codes

[grave reef]

I uploaded your attachments as Gist.

[stone trellis]

I hope you got the files

to run the files
you need to create the JAR file

javac Client.java
jar cfe Client.jar Client Client.class

javac Server.java
jar cfe Server.jar Server Server.class ClientThread.class

this are the commands

urgent help needed

Here it stucks

The Server responds but the client get stucked

[boreal trout]

it wouldn't work since there are hardcoded paths
You should use relative paths and resource, and use an ide and build tool

[stone trellis]

oh yeah i forgot to tell you this

before compiling

you should change the path in the server.java

[boreal trout]

...or you could make so we wouldn't need to do this

[stone trellis]

sorry didnt understand this

private String directoryName = "C:\Users\Shind\OneDrive\Desktop\FTP";
instead of this drop your path

[stone trellis]

can you repeat i didnt understand this

[boreal trout]

.

[stone trellis]

please can you try changing the path once

[boreal trout]

I won't run it anyway

There are several things that are bug at best

no idea if it is what is causing your problems

but here they are

also do you get any error ?

for example

you are creating a scanner on System.in twice

and then you are closing it

it cannot worklike this

you must only create one scanner

and don't close it

[stone trellis]

there was a code provided to me
in that there was a comment
// Give the name of directory of the files at the server

[stone trellis]

where ?

[boreal trout]

ctrl+f System.in

[stone trellis]

yeah i got thayt

i tried every possible thing from my side still it shows the same

[boreal trout]

wdym

[stone trellis]

i am trying to fix this

[boreal trout]

@stone trellis data = in.read() is your code stuck here in the client ?

[stone trellis]

let me check

[stone trellis]

yes i guess

[boreal trout]

you guess ?

[stone trellis]

if i know this why i would be here ???

[boreal trout]

debug it please

put a breakpoint and see

or at least use prints

[stone trellis]

wait

try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
                int data;
                while ((data = in.read()) != -1) {
                    writer.write(data);
                }
                System.out.println("File \"" + fileName + "\" downloaded successfully.");
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("Error writing to file: " + e.getMessage());
            }
        } else {
            System.out.println("Server response:\n" + response);
        }
    }

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

this is the code

i used int but the file has words

so is this the error

see this

@boreal trout

[boreal trout]

can you show what's inside the file please ?

[stone trellis]

HELLO WORLD

is it printing in bytes or bits?

private static void sendFile(String fileName, File directory, PrintWriter outgoing, BufferedReader incoming,
            Socket connection) {
        File file = new File(directory, fileName);

        if (file.exists() && file.isFile()) {
            try (BufferedInputStream fileInputStream = new BufferedInputStream(new FileInputStream(file))) {
                byte[] buffer = new byte[1024];
                int bytesRead;

                outgoing.println("OK");
                outgoing.flush();

                OutputStream outputStream = connection.getOutputStream();

                while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                    outputStream.write(buffer, 0, bytesRead);
                }

                outputStream.flush();
                System.out.println("Sent OK response for file: " + fileName);
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            outgoing.println("ERROR file not found");
            outgoing.flush();
            System.out.println("Sent ERROR file not found response for file: " + fileName);
        }
    }

This is a part of SERVER.JAVA

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

here i done Byte

[boreal trout]

ah I see

[stone trellis]

yep

[boreal trout]

this is indeed "HELLO WORLD\r\n"

but

you are testing against -1 to end the loop

but in the server

you never send -1 dont you ?

[stone trellis]

while ((bytesRead = fileInputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}

[boreal trout]

yes you never send -1

[stone trellis]

yep

now?

[boreal trout]

now you need to fix it

[stone trellis]

how

[boreal trout]

how do you think ?

the client is waiting for -1

the server never send it

what's the problem ?

and how to fix it ?

[stone trellis]

mmm

idk

[boreal trout]

think a bit

[stone trellis]

while ((bytesRead = fileInputStream.read(buffer)) != -1) {
    outputStream.write(buffer, 0, bytesRead);
}

// Signal the end of the file transfer
outputStream.write(-1);
outputStream.flush();```

???

[boreal trout]

yes

[stone trellis]

does it fixed now?

should i try?

[boreal trout]

yes

[stone trellis]

should i also do the same in client?

int bytesRead;
while ((bytesRead = in.read()) != -1) {
    // Check for the end of the file signal
    if (bytesRead == -1) {
        break;
    }
    // Process the received data
    // ...
}

[grave reef]

Detected code, here are some useful tools:

[hoary kite]

If you use java 9, there is also this method InputStream#transferTo(OutputStream out)

[boreal trout]

you are alreday doing it, why do you want to do it twice ?

[boreal trout]

the problem is that there is no way to tell it when to stop

[stone trellis]

try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
                int bytesRead;
                while ((bytesRead = in.read()) != -1) {
                    writer.write(bytesRead);
                    System.out.println(bytesRead);
                    if (bytesRead == -1) {
                        break;
                    }
                }
                System.out.println("File \"" + fileName + "\" downloaded successfully.");
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("Error writing to file: " + e.getMessage());
            }
        } else {
            System.out.println("Server response:\n" + response);
        }
    }

i mean for this

[boreal trout]

yes ?

[stone trellis]

this is of client side

[boreal trout]

as I said

it doesn't makde any sense

why would you check the condition twice ?

[hoary kite]

it fully consumes the input stream, so im not sure what you mean

[boreal trout]

yes that's the problem

[stone trellis]

lol yes sorrry sorry

[hoary kite]

alathreon is right, you are already checking if the input reads -1, no need to check again and then break the loop

[boreal trout]

@stone trellis you are basially doing

if(foo == -1) break;
if(foo == -1) break;

why do it twice ?

[stone trellis]

yes i got it

let me check now

it still stucks

[boreal trout]

show the code

[stone trellis]

try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
                int data;
                while ((data = in.read()) != -1) {
                    writer.write(data);
                    // System.out.println(data);
                }
                System.out.println("File \"" + fileName + "\" downloaded successfully.");
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("Error writing to file: " + e.getMessage());
            }
        } else {
            System.out.println("Server response:\n" + response);
        }
    }

Client.java

[grave reef]

Detected code, here are some useful tools:

Formatted code

try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
  int data;
  while ((data = in.read()) !=  - 1) {
    writer.write(data);
    // System.out.println(data);
  }
  System.out.println("File \"" + fileName + "\" downloaded successfully.");
} catch (IOException e) {
  e.printStackTrace();
  System.out.println("Error writing to file: " + e.getMessage());
}
}
else {
System.out.println("Server response:\n" + response);
}
}

[stone trellis]

private static void sendFile(String fileName, File directory, PrintWriter outgoing, BufferedReader incoming,
            Socket connection) {
        File file = new File(directory, fileName);

        if (file.exists() && file.isFile()) {
            try (BufferedInputStream fileInputStream = new BufferedInputStream(new FileInputStream(file))) {
                byte[] buffer = new byte[1024];
                int bytesRead;

                outgoing.println("OK");
                outgoing.flush();

                OutputStream outputStream = connection.getOutputStream();

                while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                    outputStream.write(buffer, 0, bytesRead);
                }

                // Signal the end of the file transfer
                outputStream.write(-1);
                outputStream.flush();
                System.out.println("Sent OK response for file: " + fileName);
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            outgoing.println("ERROR file not found");
            outgoing.flush();
            System.out.println("Sent ERROR file not found response for file: " + fileName);
        }
    }

Server.java

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

still it stucks after yes or no

but it only stucks for GET Command
LIST command is working fine

[boreal trout]

add back the print

[stone trellis]

it shows the same this

[boreal trout]

and see whats happening

[stone trellis]

thing

i did it

[boreal trout]

please show a screenshot

[stone trellis]

it prints the same thing

wait

see

@boreal trout

[boreal trout]

and if you add back the prints ?

[stone trellis]

sorry

@boreal trout

can we join VC?

[boreal trout]

65533 🤔

no

[hoary kite]

yeah that confused me too

[stone trellis]

i guess its of -1

[boreal trout]

why

[stone trellis]

i guessed

[boreal trout]

I mean yea

but why

[stone trellis]

// Process the received data
    System.out.print((char) bytesRead); // assuming it's text data
}

i may try this

 try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
                int data;
                while ((data = in.read()) != -1) {
                    writer.write(data);
                    System.out.println(data);
                    // Check for the end of the file signal
                    if (data == -1) {
                        break;
                    }
                    // Process the received data
                    System.out.print((char) data); // assuming it's text data

                }
                System.out.println("File \"" + fileName + "\" downloaded successfully.");
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("Error writing to file: " + e.getMessage());
            }
        } else {
            System.out.println("Server response:\n" + response);
        }
    }

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

i done this

this is the output

this are the assci numbers

ascii

i dont know why there is 65533
?

is it

the special character (65533) in the client. This character often represents the replacement character (�) and may indicate a problem with encoding or reading the file.

i just stack overflow

they say This character often represents the replacement character (�) and may indicate a problem with encoding or reading the file.

[boreal trout]

I already told you to delete this if

[stone trellis]

okay wait

[boreal trout]

is this the server ?

[stone trellis]

yes

[stone trellis]

should i do this ?

[boreal trout]

?

[stone trellis]

no sorry its of client

[boreal trout]

client ?

[stone trellis]

yes

[boreal trout]

ah

[stone trellis]

i done this in the client

[boreal trout]

in the server

instead of sending -1

try to send 0

and see what the client get

just to test

[stone trellis]

try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
                int data;
                while ((data = in.read()) != -1) {
                    writer.write(data);
                    System.out.println(data);
                    // Process the received data
                    System.out.print((char) data); // assuming it's text data

                }
                System.out.println("File \"" + fileName + "\" downloaded successfully.");
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("Error writing to file: " + e.getMessage());
            }
        } else {
            System.out.println("Server response:\n" + response);
        }
    }

the latest client.java

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

okay wait

and i also need to that inn client

isntit?

[boreal trout]

no

don't touch the client

[stone trellis]

oh wait

i done 0 in server as well as client

and this is the output

it worked and the file has been saved with text hello world
but there is another error now

[boreal trout]

no

please do what I say

[stone trellis]

okay wait

check

server side i changed

and client side i didnt

and it worked

but the same error of scnanner class

[boreal trout]

wait

it works now ?

what did you change ?

ah

no

[stone trellis]

what ??

i did it right

[boreal trout]

no

it's -1

not 0

[stone trellis]

PS D:\Assignmensts\assignment 2> java Client 127.0.0.1 7210
>>
Connecting to server 127.0.0.1:7210
---Connection Successful---
Received Worker ID: 25
Enter command (type 'exit' to close connection): GET test.txt
Sending "GET test.txt" to server
File "test.txt" already exists. Do you want to overwrite it? (yes/no): yes
File "test.txt" downloaded successfully.
Enter command (type 'exit' to close connection): Exception in thread "main" java.util.NoSuchElementException: No line found
        at java.base/java.util.Scanner.nextLine(Scanner.java:1660)
        at Client.main(Client.java:30)
PS D:\Assignmensts\assignment 2> 

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

yes in client its -1 and in server its 0

[boreal trout]

yes that's the problem I told you earlier, only create one reader/scanner on System.in and never close it

[boreal trout]

no

it's -1 in both

[stone trellis]

check it

[stone trellis]

...

also check the file names in the tab

okay??

only after this changes

[stone trellis]

this is the output

[boreal trout]

I told you severeal times

[boreal trout]

.

[stone trellis]

wait

check this

[grave reef]

I uploaded your attachments as Gist.

[stone trellis]

never closed any scanner

still the same error

[boreal trout]

you are
try (Scanner userInput = new Scanner(System.in)) {
String overwriteChoice = userInput.nextLine().toLowerCase();

                if (!overwriteChoice.equals("yes")) {
                    System.out.println("Download canceled.");
                    return;
                }
            }

[stone trellis]

so what i should do

[boreal trout]

create only one scanner

and don't close it

like I said several times

[stone trellis]

yep so i need to remove the try catch>

?

[boreal trout]

yes and only create one scanner

[stone trellis]

private static void handleGetResponse(String command, String response, BufferedReader in, Scanner scanner) throws IOException {
        if (response.equals("OK")) {
            String fileName = command.substring(4).trim();
            File file = new File(fileName);

            if (file.exists()) {
                System.out.print("File \"" + fileName + "\" already exists. Do you want to overwrite it? (yes/no): ");
                String overwriteChoice = scanner.nextLine().toLowerCase();

                if (!overwriteChoice.equals("yes")) {
                    System.out.println("Download canceled.");
                    return;
                }
            }

            try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {
                int data;
                while ((data = in.read()) != -1) {
                    writer.write(data);
                }
                System.out.println("File \"" + fileName + "\" downloaded successfully.");
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("Error writing to file: " + e.getMessage());
            }
        } else {
            System.out.println("Server response:\n" + response);
        }
    }

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

seee

like this/

?

[boreal trout]

yes

[stone trellis]

okay

wait let me chekc the output

done

done

yeahhhh

thanks a lot man

now see thisss

Connecting to server 127.0.0.1:7210
---Connection Successful---
Received Worker ID: 33
Enter command (type 'exit' to close connection): GET test.txt
Sending "GET test.txt" to server
File "test.txt" already exists. Do you want to overwrite it? (yes/no): yes    
File "test.txt" downloaded successfully.
Enter command (type 'exit' to close connection): GET text.txt
Sending "GET text.txt" to server
java.net.SocketException: An established connection was aborted by the software in your host machine
        at java.base/sun.nio.ch.SocketDispatcher.write0(Native Method)        
        at java.base/sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:54)
        at java.base/sun.nio.ch.NioSocketImpl.tryWrite(NioSocketImpl.java:394)
        at java.base/sun.nio.ch.NioSocketImpl.implWrite(NioSocketImpl.java:410)
        at java.base/sun.nio.ch.NioSocketImpl.write(NioSocketImpl.java:440)   
        at java.base/sun.nio.ch.NioSocketImpl$2.write(NioSocketImpl.java:819) 
        at java.base/java.net.Socket$SocketOutputStream.write(Socket.java:1195)
        at java.base/java.net.Socket$SocketOutputStream.write(Socket.java:1190)
        at java.base/java.io.DataOutputStream.writeBytes(DataOutputStream.java:277)
        at Client.main(Client.java:42)
PS D:\Assignmensts\assignment 2>

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

this output is of client

[boreal trout]

did you close the server ?

[stone trellis]

never

[stone trellis]

this is of server output

are you there?

@boreal trout

[boreal trout]

at ClientHandler.sendFile(Server.java:107)

[stone trellis]

what?

[boreal trout]

that's impossible

please show this line

[stone trellis]

outputStream.write(buffer, 0, bytesRead);

private static void sendFile(String fileName, File directory, PrintWriter outgoing, BufferedReader incoming, Socket connection) {
    File file = new File(directory, fileName);

    if (file.exists() && file.isFile()) {
        try (BufferedInputStream fileInputStream = new BufferedInputStream(new FileInputStream(file))) {
            byte[] buffer = new byte[1024];
            int bytesRead;

            outgoing.println("OK");
            outgoing.flush();

            OutputStream outputStream = connection.getOutputStream();

            while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }

            // Signal the end of the file transfer
            outputStream.write(-1);
            outputStream.flush();
            System.out.println("Sent OK response for file: " + fileName);
        } catch (IOException e) {
            e.printStackTrace();
        }
    } else {
        outgoing.println("ERROR file not found");
        outgoing.flush();
        System.out.println("Sent ERROR file not found response for file: " + fileName);
    }
}

ChatGPT suggested me this code

for the error

SHould i try this??

@boreal trout

hello

@boreal trout

[stone trellis]

no this wont works and the terminal again get stucks

[boreal trout]

sorry, ill go to sleep

but you have a weird out of bounds of index -1

[stone trellis]

hmmm

bro its 5am in india

and i am still working

from 3pm now its 5am

It seems like there's an issue in the sendFile method of your ClientHandler class, specifically in this part:

while ((bytesRead = fileInputStream.read(buffer)) != 0) {
    outputStream.write(buffer, 0, bytesRead);
}

The condition (bytesRead = fileInputStream.read(buffer)) != 0 means that the loop will continue as long as bytesRead is not equal to 0. However, it should be checking for -1 instead of 0 to indicate the end of the file.

You can fix it by changing the condition to:

while ((bytesRead = fileInputStream.read(buffer)) != -1) {
    outputStream.write(buffer, 0, bytesRead);
}

This change ensures that the loop continues until the end of the file is reached, as read returns -1 when there is no more data to read. Update your sendFile method with this modification and see if it resolves the issue.

[grave reef]

Detected code, here are some useful tools:

[stone trellis]

this is given by chatgpt

but with this the terminal get stucked

@boreal trout Thanks a lot that you helped me till now, thanks a lot man

now i also sleep a little then tomorrow i will try this again

good night

[stone trellis]

@boreal trout hey you there?

Anyone here?

[stone trellis]

any helper here ??

@cyan coral

please help mee

in this

i need your help

@stuck pagoda

@shrewd merlin

[grave reef]

Of course! I'm here to help. What do you need assistance with?

[stone trellis]

?chat

[grave reef]

Looks like you attempted to use a command? Please note that we only use slash-commands on this server 🙂

Try starting your message with a forward-slash / and Discord should open a popup showing you all available commands.
A command might then look like /foo 👍

This exception is thrown when you try to access an element in an array or collection using an index that is outside the valid range of indices for that array or collection.

In this specific case, the exception message indicates that the range [0, 0 + -1) is out of bounds for an array with a length of 1024. This means that you are trying to access elements from index 0 to index -1, which is not a valid range.

To fix this issue, you need to make sure that the indices you use to access elements are within the valid range of indices for the array or collection. Double-check your code and ensure that you are using correct indices when accessing elements.

[cyan coral]

no need to ping random helper not related to your question -> #rules
that is just annoying and doesnt really create interest in helping you

[stone trellis]

you are a java helper

[cyan coral]

yeah and?

we all do this voluntarily, I am not forced to help you at all

instead you should try to get more interest into your question by improving it with more information, ...

[stone trellis]

@boreal trout HELLO BRO THANKS for helping me for everything

the code is runing well now

but there is a new issue regarding the Server Socket after completing one request of GET command
the server is automatically closed but the client side is still open
and when i put next command it thorws the error that the connection is aborted

@boreal troutSorry for distrubing you, but i felt you are a good person and wont be pissed of my questions

can you help me?

[boreal trout]

@stone trellis can you stop mentionning people please ?

[stone trellis]

yes

really sorry

can you help me?

[boreal trout]

Later

[stone trellis]

ohh okay