sockets - Python 3 ftplib error "Name or service not known"

Question

I am trying to download a file from FTP server using ftplib library of Python 3.

Here is the relevant code-

ftp = ftplib.FTP("ftp://library.daisy.org:21/User_****/Wise & Otherwise-22.zip") 
ftp.login("xxxxx", "xxxxxxx") 
ftp.cwd(path)
ftp.retrbinary("RETR " + filename, open(filename, 'wb').write)
ftp.quit()

When I try to run the script the following error shows up-

Traceback (most recent call last):
  File "reader.py", line 604, in <module>
    sp.process_user_choice()
  File "reader.py", line 72, in process_user_choice
    self.download_books()   File "reader.py", line 324, in download_books
    ftp = ftplib.FTP(all_urls[response]) 
  File "/usr/lib/python3.5/ftplib.py", line 118, in __init__
    self.connect(host)
  File "/usr/lib/python3.5/ftplib.py", line 153, in connect
    source_address=self.source_address)
  File "/usr/lib/python3.5/socket.py", line 694, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
  File "/usr/lib/python3.5/socket.py", line 733, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -2] Name or service not known

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Some notes-

1. I have the correct URL and credentials
2. I am behind a proxy server

Answer 1

The host argument of FTP constructor takes, as the name suggests, a hostname only, like library.daisy.org. You are passing in a whole URL.

This is correct:

ftp = ftplib.FTP("library.daisy.org")

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The full path goes to an argument of the RETR command:

ftp.retrbinary("RETR User_****/Wise & Otherwise-22.zip", open(filename, 'wb').write)

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As you are connecting via proxy, you have to cater for that too.

There are lot of questions here covering that part. But you didn't tell us what kind of proxy you are using, so I cannot be more specific.