HTTP client hangs if zero-length file sent

[mk90]

HTTP-Daemon/lib/HTTP/Daemon.pm

Line 546 in b902312

print $self "Content-Length: $size$CRLF" if $size;

Using send_file_response with empty file suppress "Content-Length" header line, because "if $size" contstruction treated as false.

Then library succsessfully complete operation with RC_OK code, but HTTP client waits data from server, and timeout occured as a result.

Removing "if $size" resolve this problem.

[oalders]

That's not great! @vanHoesel, do you know what the correct behaviour here is? Just send a Content-Length of 0? It's not clear to me what the use case is for sending an empty file.

[ppisar]

It depends on HTTP version and transfer encoding. But in general if the size is known to be 0, it should be indicated with "0". See https://www.ietf.org/rfc/rfc7230.html#section-3.3.2 for HTTP/1.1 and https://www.ietf.org/rfc/rfc1945.html#section-10.4 for HTTP/1.0.