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#include "httpd.h"
#include "http_core.h"
#include "http_config.h"
#include "http_log.h"
#include "http_protocol.h"
#include "ap_config.h"
#include "apr_optional.h"
/* Must be declared if modsecurity.h is not included */
APR_DECLARE_OPTIONAL_FN(void, modsec_register_tfn, (const char *name, void *fn));
/**
* This function will be invoked by
* ModSecurity to transform input.
*/
static int reverse(apr_pool_t *mptmp, unsigned char *input,
long int input_len, char **rval, long int *rval_len)
{
/* Transformation functions can choose to do their
* thing in-place, overwriting the existing content. This
* is normally possible only if the transformed content
* is of equal length or shorter.
*
* If you need to expand the content use the temporary
* memory pool mptmp to allocate the space.
*/
/* Reverse the string in place, but only if it's long enough. */
if (input_len > 1) {
long int i = 0;
long int j = input_len - 1;
while(i < j) {
char c = input[i];
input[i] = input[j];
input[j] = c;
i++;
j--;
}
}
/* Tell ModSecurity about the content
* we have generated. In this case we
* merely point back to the input buffer.
*/
*rval = (char *)input;
*rval_len = input_len;
/* Must return 1 if the content was
* changed, or 0 otherwise.
*/
return 1;
}
static int hook_pre_config(apr_pool_t *mp, apr_pool_t *mp_log, apr_pool_t *mp_temp) {
void (*fn)(const char *name, void *fn);
/* Look for the registration function
* exported by ModSecurity.
*/
fn = APR_RETRIEVE_OPTIONAL_FN(modsec_register_tfn);
if (fn) {
/* Use it to register our new
* transformation function under the
* name "reverse".
*/
fn("reverse", (void *)reverse);
}
return OK;
}
static void register_hooks(apr_pool_t *p) {
ap_hook_pre_config(hook_pre_config, NULL, NULL, APR_HOOK_LAST);
}
/* Dispatch list for API hooks */
module AP_MODULE_DECLARE_DATA tfn_reverse_module = {
STANDARD20_MODULE_STUFF,
NULL, /* create per-dir config structures */
NULL, /* merge per-dir config structures */
NULL, /* create per-server config structures */
NULL, /* merge per-server config structures */
NULL, /* table of config file commands */
register_hooks /* register hooks */
};
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