FTP is a client-server oriented protocol for uploading, downloading, and managing files. The FTP server's job is to listen for incoming connections from clients and then respond to their requests. These requests include all common file and directory operations, such as listing the files in a directory, making and deleting directories, uploading files from the client machine to the server, and downloading files from the server to the client machines. FTP clients connect to FTP servers and issue commands to tell the server what to do.
- I started by writing the main method for the program. (Obviously)
- I wanted to ensure that the program would only the command and one or two parameters.
- From there, I made sure I was able to properly parse out all of the individual parts or the provided ftp server urls.
- After separating all of these out and making sure they were correct with print sttements for various values, I started in on the login() method.
- I figured that for every operation, they would need to login and quit, so I created these two methods and tested out bogus random commands.
- Using print statemments for the responses from the ftp server, I was able to see what was supposed to come next.
- From here, I implemented the different ftp commands that didn't require much back and forth communication.
- Next, I implemented the mkdir and rmdir methods with ease.
- In order to get any more functionality I had to implement PASV and figure out how to convert the pasv response into a host ip and port number.
- I then went about implementing the ls functionality, as I needed it to sort of test our the rest of the methods.
- I set up the data channel and tested what the different responses would be from this server.
- After I got ls to work I went onto the cp method.
- The cp required multiple inputs parsed for their values so I had to add specification to the inputs parsing of whether it was handling an ftp address or a local path.
- After I got this portion working, I had to figure out how to use the data channel to send and recieve files.
- After I got cp working, I just added a bool field into the cp() function in my code of whether to remove from source and sent the mv request the same route mostly.
- From here, I started testing all various inputs and adding error handling wihtin the code!
- Lastly, added some helpful documentation to the code.
- First major challenge was in the login() method where there was supposed to be mulitple consecutive sends to the server with the right info.
- In the ls implementation, I was stuck for a while trying to figure out how to set up a data channel. - With this, I had to read a lot of the provided documentation. - Print statements of the responses, and a lot of guessing helped me overcome this obstacle. - Maybe I missed the part of class where we talked about (top << 8bits) + bottom, but this was also something that notation took a while to figure out.
- Sending and receiving files over the data channel was definitely a tough part that required a lot of googling to figure out how file writing worked again. (Rusty) - With this, I was struggling for a while to figure out where to place the file and how to specify this, but turns out that the STOR and RETR methods handle this.
- The requirements of this project were pretty vague for this assignment in certain areas. I had to wait on Piazza a few days for responses to my questions in order to implement some of the final functionality. This was also a challenge in my eyes.
- I tested each individual portion very thouroughly before moving on, and also tested for a few hours at the end.
- Testing started with print statements literally everywhere. I was able to test if I was parsing the command line inputs this way as well as if the server was accepting my send()s the right way.
- I tried to add exception catching as I went but this was not enough in the end.
- Finally when I completed the code I went through and used the ls command to test most of the input functionality.
- Here are some examples of how I altered the inputs with ls to test what errors were being thrown and what was just breaking everything: - Correct implementation. - Not an ftp address. - Wrong username. - No username. - Wrong password. - No password. - No @ symbol. - Invalid hostname. - No hostname. - Invalid ports. - No port. - Invalid paths. - No paths.
- Then I switched to mv and tested with 2 params. - All tests listed for ls tested again for both. - One of the two has to be local and one has to be ftp url. - Files from and to sub-directories. - Renaming files. - To paths that do not exist. - etc.
- From here I tested all of the different commands and filled files with specific data to make sur ethey were sending over the proper info, not just garbage.
- As I did all of these tests, I went through the code I wrote and added try/catches for various invalid logins.
- I also implemented a method that would check responses for any 4XX, 5XX, or 6XX responses and error out gracefully instead of breaking when it tried to push through.