ACCF_HTTP(9)

💖 ACCF_HTTP(9) 💖

okay so bestie, this is the accf_http page from the Kernel Developer's Manual, and it's literally about giving your HTTP server a tiny bit of breathing room before it has to deal with a connection. slay. ✨

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🌸 NAME 🌸

accf_http — buffer incoming connections until a certain complete HTTP request arrives

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🎀 SYNOPSIS 🎀

options INET
options ACCEPT_FILTER_HTTP

In rc.conf(5):

kld_list="accf_http"

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🦋 DESCRIPTION 🦋

This is a filter to be placed on a socket that will be using accept() to receive incoming HTTP connections. It's giving "velvet rope for your socket," no cap. 💅

It prevents the application from receiving the connected descriptor via accept() until either a full HTTP/1.0 or HTTP/1.1 HEAD or GET request has been buffered by the kernel. iconic behavior, honestly. 🫶

If something other than a HTTP/1.0 or HTTP/1.1 HEAD or GET request is received, the kernel will allow the application to receive the connection descriptor via accept(). so it's not gonna hold your connection hostage forever, bestie. 😌

The utility of accf_http is such that a server will not have to context switch several times before performing the initial parsing of the request. This effectively reduces the amount of required CPU utilization to handle incoming requests by keeping active processes in preforking servers such as Apache low and reducing the size of the file descriptor set that needs to be managed by interfaces such as select(), poll() or kevent() based servers. highkey a whole glow-up for your server's first hello. 🔥

The accf_http kernel option is also a module that can be enabled at runtime via kldload(8) if the INET option has been compiled into the kernel. module moment fr fr. 💜

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⭐ EXAMPLES ⭐

Assuming ACCEPT_FILTER_HTTP has been included in the kernel config file or the accf_http module has been loaded, this will enable the http accept filter on the socket sok. 🐚

struct accept_filter_arg afa;

bzero(&afa, sizeof(afa));
strcpy(afa.af_name, "httpready");
setsockopt(sok, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa));

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🌈 SEE ALSO 🌈

• setsockopt(2)
• accept_filter(9)

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🧚 HISTORY 🧚

The accept filter mechanism and the accf_http filter were introduced in FreeBSD 4.0. vintage but still cute. 🎀

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👑 AUTHORS 👑

This manual page and the filter were written by Alfred Perlstein. thank you for your service, icon. 🫡

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mwah 💋 this little page says it came from Debian, dated November 15, 2000, and its manual-page name is ACCF_HTTP(9) — periodt. 💖