Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hello
I'm writing a small Perl script (http client) that only uploads files to a webserver. I do not want to use FTP. I want to use HTTP and a multipart POST.

I think I can accomplish this by using IO::Socket, creating a multipart MIME format, and stepping through the lines in the file one by one (writing to the socket). However, I do not know the protocol rules for doing this. I can send regular POSTs, but when i send the multipart POST and try to read the server response it just hangs (waiting for response). When I look at the server side nothing is uploaded. Am i missing something? 

# Read file: open(FILE, $file);
# Convert to multipart MIME & save in temp file
# Make socket connection: $socket = IO::Socket....
# Generate HTTP POST HEADER: print $socket "POST /cgi-bin/upload.pl HT
+TP/1.0\n" etc. 
# Read multipart temp file line by line and write to socket: while(<TE
+MP>){ print $socket }
# When finished (EOF): print "\n\r\n\r";
# Read server response: while(<$socket>){ print }

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Replies are listed 'Best First'.
Re: uploading a file through HTTP using multipart
by chromatic (Archbishop) on Nov 22, 2000 at 00:27 UTC
    If you are determined to do this on your own, eventually you will need to look at the HTTP standard as defined in the relevant RFCs: RFC1945 and RFC2616.

    From the information you have given, I would suggest you add an extra newline to the POST header. Also, you will need to send a 'Content-type: multipart/form-data' header and probably need to add some really ugly boundary strings. Yuck.

    If I were to do this, I would rush to the LWP-Bundle module, as it handles all of this for you already. See perldoc lwpcook and search for POST.

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Re: uploading a file through HTTP using multipart
by merlyn (Sage) on Nov 22, 2000 at 00:36 UTC
    As chromatic said, the simplest way to do this is with LWP. You want HTTP::Request::Common, from which the doc reads: 
           POST $url, [$form_ref], [Header => Value,...]
           This works mostly like GET() with POST as the method,
           but this function also takes a second optional array
           or hash reference parameter ($form_ref).  This argu-
           ment can be used to pass key/value pairs for the form
           content.  By default we will initialize a request
           using the `application/x-www-form-urlencoded' content
           type.  This means that you can emulate a HTML <form>
           POSTing like this:

             POST 'http://www.perl.org/survey.cgi',
                  [ name   => 'Gisle Aas',
                    email  => 'gisle@aas.no',
                    gender => 'M',
                    born   => '1964',
                    perc   => '3%',
                  ];

           This will create a HTTP::Request object that looks
           like this:

             POST http://www.perl.org/survey.cgi
             Content-Length: 66
             Content-Type: application/x-www-form-urlencoded

             name=Gisle%20Aas&email=gisle%40aas.no&gender=M&born=1964&
+perc=3%25

           The POST method also supports the `multi-
           part/form-data' content used for Form-based File
           Upload as specified in RFC 1867.  You trigger this
           content format by specifying a content type of
           `'form-data'' as one of the request headers.  If one
           of the values in the $form_ref is an array reference,
           then it is treated as a file part specification with
           the following interpretation:

             [ $file, $filename, Header => Value... ]

           The first value in the array ($file) is the name of a
           file to open.  This file will be read and its content
           placed in the request.  The routine will croak if the
           file can't be opened.  Use an `undef' as $file value
           if you want to specify the content directly.  The
           $filename is the filename to report in the request.
           If this value is undefined, then the basename of the
           $file will be used.  You can specify an empty string
           as $filename if you don't want any filename in the
           request.

           Sending my ~/.profile to the survey used as example
           above can be achieved by this:

             POST 'http://www.perl.org/survey.cgi',
                  Content_Type => 'form-data',
                  Content      => [ name  => 'Gisle Aas',
                                    email => 'gisle@aas.no',
                                    gender => 'M',
                                    born   => '1964',
                                    init   => ["$ENV{HOME}/.profile"],
                                  ]

           This will create a HTTP::Request object that almost
           looks this (the boundary and the content of your
           ~/.profile is likely to be different):

             POST http://www.perl.org/survey.cgi
             Content-Length: 388
             Content-Type: multipart/form-data; boundary="6G+f"

             --6G+f
             Content-Disposition: form-data; name="name"

             Gisle Aas
             --6G+f
             Content-Disposition: form-data; name="email"

             gisle@aas.no
             --6G+f
             Content-Disposition: form-data; name="gender"

             M
             --6G+f
             Content-Disposition: form-data; name="born"

             1964
             --6G+f
             Content-Disposition: form-data; name="init"; filename=".p
+rofile"
             Content-Type: text/plain

             PATH=/local/perl/bin:$PATH
             export PATH

             --6G+f--

    [download]
    No point in reinventing the wheel, when it's all nicely there for the taking.

    -- Randal L. Schwartz, Perl hacker

[reply]
[d/l]
      Thanks,

      However, I am having a similar problem to the one described in node 32916. I have the Multipart MIME constructed, but I cannot POST it correctly. When I do a post and then wait for the server response it hangs indefinitely. What is wrong? I think I am very close to getting it to work, I just need to terminate the multipart or something...

      I do not want to rewrite the thing just so I can use some module.

      Thank You.

[reply]
Re: uploading a file through HTTP using multipart
by amelinda (Friar) on Nov 23, 2000 at 05:45 UTC
    If I could give you only one piece of advice, it would be this: Use LWP

    Of course, if you don't want to do that (or can't for some convoluted reason), you might want to take a look at the insanity I once had to deal with. Be warned, the RFC's for MIME are awful and difficult to read.

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Re: uploading a file through HTTP using multipart
by strredwolf (Chaplain) on Nov 22, 2000 at 07:51 UTC
[reply]
Re: uploading a file through HTTP using multipart
by tune (Curate) on Nov 22, 2000 at 12:52 UTC
    The CGI module is also capable to handle your problem. It was very useful for me, however I did not want to trick with it. Just upload the file and save to a temporary place, and deny if it was too big. Search the string 'upload' in the manual of CGI.pm! :-)

    -- tune

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