Hacker News Reader

Comment by d33 | Hacker News Reader

That looks way oversimplified. I once wrote a minimal HTTP server in Lua for Nmap project and part of the problem was UTF8 security. Consider get_next_char_len function here to see some of the edge cases:

https://github.com/nmap/nmap/blob/b7a5a6/ncat/scripts/httpd....

View on HN

Mimimal but useful. I just tried this httpd.lua script with djb's tcpserver and was pleasantly surprised. It is quick and handles large PDFs well enough. I like that there are no third party libraries. If directory listing and output for video could be added I might try using something like this on a local LAN as a replacement for the httpd binary I am using.

Glad to hear you like it! What do you mean by output for video? As for video listing, Lua doesn't provide a cross-platform way to do this, but I might have hacks for Unix/Windows that parse the output of dir/ls commands. Interested? Can't promise I find it though.

Briefly tested with a few filetypes and a couple of browsers, including Safari. Problem loading video/mp4, i.e., problem with "HTTP streaming". Maybe need to handle Range: header?

Of course, any examples in Lua of different approaches to UNIX directory listing via HTTP are appreciated. Still a Lua noob.

The Lua code is just excessively verbose.

What do you mean? How else would you implement a check for whether the prefix length is valid?

Here's the code to do it: https://github.com/skeeto/branchless-utf8/blob/master/utf8.h

It's pretty straightforward. He uses a lookup table for the first byte ("lengths") and then later checks that subsequent bytes have the correct continuation prefix (0xc0 mask / 0x2a value).

I think it checks all of the same conditions as your Lua code.

Reply on news.ycombinator.com