File Input Validation

[darkmast2]

I was wondering if anyone can help me with a little problem i've been having.

I have a perl script which I use to take in a users input from a text box on an html page and then print it into a text file.

I would like to know how to check the users input before sending the data to the text file. I ask this because when they type something in it gets sent to the file okay, but if they don't type something in a blank line gets send to the file. I thought about using an if statement but not sure on how to do it.


Here is my program:

#!/usr/local/bin/perl.exe

#print"HTTP/1.0 200 OK\n";
#print"Content-type: text/html\n\n";

require ("c:/perl/lib/shellwords.pl"

$ASCII_ten = pack("c", 10);
$ASCII_thirteen = pack("c", 13);
$response_page = "

http://pc4180/message.htm\n\n";

sub Web_Direct {
#Ouput success message.
#
print "Location: $response_page";
}

sub User_Data {
local (%user_data, $user_string, $name_value_pair,
@name_value_pairs, $name, $value);

# If the data was sent via POST, then it is available
# from standard input. Otherwise, the data is in the
# QUERY_STRING environment variable.
#
if ($ENV{'REQUEST_METHOD'} eq "POST&quot {
read (STDIN, $user_string, $ENV{'CONTENT_LENGTH'});
} else {
$user_string = $ENV{'QUERY_STRING'};
}

# This line changes the + signs to spaces.
#
$user_String =~ s/\+/ /g;

# This line places each name/value pair as a separate
# element in the name_value_pairs array.
#
@name_value_pairs = split(/&/, $user_string);

# This code loops over each element in the name_value_pairs
# array, splits it on the = sign, and places the value
# into the user_data associative array with the name as the
# key.
#
foreach $name_value_pair (@name_value_pairs) {
($name, $value) = split (/=/, $name_value_pair);

# These two lines decode the values from any URL hexadecimal
# encoding. The first section searches for a hexadecimal
# number and the second part converts the hex number to
# decimal and returns the character equivalent.
#
$name =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/ge;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C&quot,hex($1)/ge;

# If the name/value pair has already been given a value,
# as in the case of multiple items being selected, then
# separate the items with a ":".
#
if (defined($user_data{$name})) {
$user_data{$name} .= ":" . $value;
} else {
$user_data{$name} = $value;
}
}
return %user_data;
};


%data_received = &User_Data;

# Remove any carriage returns or newline characters that
# the user may have entered.
#
foreach $key (keys(%data_received)) {
$data_received{$key} =~s/$ASCII_ten//ge;
$data_received{$key} =~s/$ASCII_thirteen/$space/ge;
}

# Open the text file for appending the information to
# or display error message if unableto open file.
#
open(TEXT, '>>text_file.txt') || die "couldn't open file: $!";

@data_received = %data_received;
foreach $data_received (@data_received)
{
($first, $last) = split('\+', $data_received);
$data_received =~ s/\+/ /gi;
}

# extract the name from the array and print it to the
# text file.
#
print TEXT @data_received[1];


# Print a newline character to the end of the name.
#
print TEXT "\n";

# Close the text file or display an error message
# if the file cannot be closed.
#
close(TEXT) || die "can't close file: $!";

&Web_Direct;

 

[tsdragon]

You can use a regular expression to check for all whitespace:

if ( $data_received =~ /^\s*$/ ) {
   # line is all whitespace
}

Tracy Dryden
tracy@bydisn.com

http://www.bydisn.com

Meddle not in the affairs of dragons,
For you are crunchy, and good with mustard.