csrf.c File Reference

Stateless CSRF protection middleware implementation. More...

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "csilk/core/internal.h"
#include "csilk/csilk.h"

Include dependency graph for csrf.c:

Functions
void	csilk_csrf_middleware (csilk_ctx_t *c)
	Stateless CSRF protection middleware (cookie + header token comparison).
int	csilk_csrf_generate_token (char *buf, size_t buf_size)
	Generate a cryptographically random CSRF token.

Detailed Description

Stateless CSRF protection middleware implementation.

Copyright

MIT License

Function Documentation

csilk_csrf_generate_token()

int csilk_csrf_generate_token	(	char *	buf,
		size_t	buf_size
	)

Generate a cryptographically random CSRF token.

Reads 16 bytes from /dev/urandom and formats them as a 32-character hex string (plus null terminator). If /dev/urandom cannot be opened, falls back to a weak PRNG seeded with time XOR pid.

Parameters

buf	Output buffer to receive the null-terminated hex token.
buf_size	Size of the output buffer. Must be at least 33 bytes.

Returns

0 on success, -1 if buf is NULL, buf_size < 33, or fread fails.

Warning

The fallback path uses rand_r() which is NOT cryptographically secure. Production deployments should always ensure /dev/urandom is available.

csilk_csrf_middleware()

void csilk_csrf_middleware

(

csilk_ctx_t *

c

)

Stateless CSRF protection middleware (cookie + header token comparison).

Stateless CSRF protection middleware.

On safe HTTP methods (GET, HEAD, OPTIONS), the middleware ensures a CSRF cookie called "csrf_token" is present (generating one if missing) and proceeds to the next handler.

On state-changing methods (POST, PUT, DELETE, etc.), it validates the X-CSRF-Token request header against the csrf_token cookie. If the tokens do not match or the header is absent, a 403 Forbidden response is returned and the pipeline is aborted.

Parameters

c	The request context.

Note

Must be registered before any handler that mutates server state.

Warning

The token is generated from /dev/urandom when available, with a weak fallback (time + pid). In high-security deployments, ensure /dev/urandom is accessible.