You probably forgot to use "binmode" built-in function, which makes sence for text-mode or binary-mode.

Otherwise, if you're inside perl script, then perl makes UNIX-like line endings, for example in HERE-IN strings and inside any strings:

$a=<<"EOS";
abcd
efgh
EOS
[download]

and

$a="abcd
efgh
";
[download]

and

$a="abcd\nefgh\n";
[download]

are the same.