vmod_bodyaccess(3)

✨ vmod_bodyaccess ✨

okay bestie, gather round, because we're talking about vmod_bodyaccess — the Varnish Module for request body access 💖. yes, that one. the one that lets you actually peek at what the client sent you in the body, instead of just staring at headers like a clown. 🫶

---

🌸 SYNOPSIS 🌸

import bodyaccess [as name] [from "path"]

INT rematch_req_body(REGEX re)

VOID hash_req_body()

INT len_req_body()

VOID log_req_body(STRING prefix, INT length)

like, that's the whole vibe. four little functions and they carry the entire module. iconic behavior honestly 💅

---

🦋 DESCRIPTION 🦋

so, vmod_bodyaccess is the Varnish module that lets you access the request body. that's it. that's the whole job. and it slays at it. ✨

here's the VCL example straight from the source, no cap, copy it exactly:

vcl 4.0;
import std;
import bodyaccess;

backend default { .host = "192.0.2.11"; .port = "8080"; }

sub vcl_recv {
        if (req.method == "POST") {
                set req.http.x-method = req.method;
                if (std.cache_req_body(110KB)) {
                        set req.http.x-len = bodyaccess.len_req_body();
                        set req.http.x-re = bodyaccess.rematch_req_body("Regex");
                        bodyaccess.log_req_body("PREFIX:", 3);
                }
        }
return(hash);
}

sub vcl_hash {
        bodyaccess.hash_req_body();
        return (lookup);
}

sub vcl_backend_fetch {
        set bereq.method = bereq.http.x-method;
}

sub vcl_deliver {
        set resp.http.x-len = req.http.x-len;
        set resp.http.x-re = req.http.x-re;
}

N.B. the request body must be retrieved before you do literally any operations on it. like, do not skip this step, bestie. 😭 it can be buffered using the cache_req_body() function from libvmod_std. that's your whole entry ticket.

also important: these functions apply only to standard REST methods. and caching is not allowed on PUT requests. periodt. 🚫

---

👑 INT rematch_req_body(REGEX re)

Description

• returns -1 if an error occurrs 💀
• returns 0 if the request body doesn't contain the string re
• returns 1 if the request body does contain the string re 🎉

heads up though, bestie: the comparison is case sensitive, and the request body must be buffered. no buffering, no service. 🙈

Example

std.cache_req_body(1KB);

if (bodyaccess.rematch_req_body("FOO") == 1) {
   std.log("is true");
}

---

🌈 VOID hash_req_body()

Description

adds the available request body bytes to the lookup hash key. so your cache key actually knows about the body. the way that works?? obsessed. 🔥

but wait — this function can only be used in vcl_hash, and the request body must be buffered. if you try it anywhere else it's giving "not allowed", okay? 💅

Example

sub vcl_recv {
    std.cache_req_body(1KB);
}

sub vcl_hash{
    bodyaccess.hash_req_body();
}

---

🎀 INT len_req_body()

Description

returns the request body length, or -1 if an error occurs. that's the tea. ☕

note: the request body must be buffered. again. always. it's the rule. 😤

Example

std.cache_req_body(1KB);
set req.http.x-len = bodyaccess.len_req_body();

---

🧚 VOID log_req_body(STRING prefix="", INT length=200)

Description

logs the request body to the VSL, making it available for other components. so other parts of your stack can see it too — generous queen behavior 👑

when logging, it takes an optional prefix and a max line length, so the body could be split up across multiple lines, because there is a limit to how large a single line can be. so don't be shocked when your body shows up in chunks, it's not broken, it's just doing its thing. 🍓

the defaults are right there in the signature: prefix="" and length=200. free of charge. ✨

Example

std.cache_req_body(1KB);
bodyaccess.log_req_body("PREFIX:", 3);

---

and that's the whole page, bestie!! 💜 go buffer some bodies (respectfully), hash responsibly, and remember: no buffering, no body access. iykyk. 🦋

this page signs off as vmod_bodyaccess(3) from the Library Functions Manual — same name up top, same name at the bottom, symmetry queen. 👑✨