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#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include "base.h"
#include "log.h"
#include "buffer.h"
#include "plugin.h"
#include "inet_ntop_cache.h"
/**
* mod_evasive
*
* we indent to implement all features the mod_evasive from apache has
*
* - limit of connections per IP
* - provide a list of block-listed ip/networks (no access)
* - provide a white-list of ips/network which is not affected by the limit
* (hmm, conditionals might be enough)
* - provide a bandwidth limiter per IP
*
* started by:
* - w1zzard@techpowerup.com
*/
typedef struct {
unsigned short max_conns;
} plugin_config;
typedef struct {
PLUGIN_DATA;
plugin_config **config_storage;
plugin_config conf;
} plugin_data;
INIT_FUNC(mod_evasive_init) {
plugin_data *p;
p = calloc(1, sizeof(*p));
return p;
}
FREE_FUNC(mod_evasive_free) {
plugin_data *p = p_d;
UNUSED(srv);
if (!p) return HANDLER_GO_ON;
if (p->config_storage) {
size_t i;
for (i = 0; i < srv->config_context->used; i++) {
plugin_config *s = p->config_storage[i];
free(s);
}
free(p->config_storage);
}
free(p);
return HANDLER_GO_ON;
}
SETDEFAULTS_FUNC(mod_evasive_set_defaults) {
plugin_data *p = p_d;
size_t i = 0;
config_values_t cv[] = {
{ "evasive.max-conns-per-ip", NULL, T_CONFIG_SHORT, T_CONFIG_SCOPE_CONNECTION },
{ NULL, NULL, T_CONFIG_UNSET, T_CONFIG_SCOPE_UNSET }
};
p->config_storage = calloc(1, srv->config_context->used * sizeof(specific_config *));
for (i = 0; i < srv->config_context->used; i++) {
plugin_config *s;
s = calloc(1, sizeof(plugin_config));
s->max_conns = 0;
cv[0].destination = &(s->max_conns);
p->config_storage[i] = s;
if (0 != config_insert_values_global(srv, ((data_config *)srv->config_context->data[i])->value, cv)) {
return HANDLER_ERROR;
}
}
return HANDLER_GO_ON;
}
#define PATCH(x) \
p->conf.x = s->x;
static int mod_evasive_patch_connection(server *srv, connection *con, plugin_data *p) {
size_t i, j;
plugin_config *s = p->config_storage[0];
PATCH(max_conns);
/* skip the first, the global context */
for (i = 1; i < srv->config_context->used; i++) {
data_config *dc = (data_config *)srv->config_context->data[i];
s = p->config_storage[i];
/* condition didn't match */
if (!config_check_cond(srv, con, dc)) continue;
/* merge config */
for (j = 0; j < dc->value->used; j++) {
data_unset *du = dc->value->data[j];
if (buffer_is_equal_string(du->key, CONST_STR_LEN("evasive.max-conns-per-ip"))) {
PATCH(max_conns);
}
}
}
return 0;
}
#undef PATCH
URIHANDLER_FUNC(mod_evasive_uri_handler) {
plugin_data *p = p_d;
size_t conns_by_ip = 0;
size_t j;
if (con->uri.path->used == 0) return HANDLER_GO_ON;
mod_evasive_patch_connection(srv, con, p);
/* no limit set, nothing to block */
if (p->conf.max_conns == 0) return HANDLER_GO_ON;
for (j = 0; j < srv->conns->used; j++) {
connection *c = srv->conns->ptr[j];
/* check if other connections are already actively serving data for the same IP
* we can only ban connections which are already behind the 'read request' state
* */
if (c->dst_addr.ipv4.sin_addr.s_addr == con->dst_addr.ipv4.sin_addr.s_addr &&
c->state > CON_STATE_REQUEST_END) {
conns_by_ip++;
if (conns_by_ip > p->conf.max_conns) {
log_error_write(srv, __FILE__, __LINE__, "ss",
inet_ntop_cache_get_ip(srv, &(con->dst_addr)),
"turned away. Too many connections.");
con->http_status = 403;
return HANDLER_FINISHED;
}
}
}
return HANDLER_GO_ON;
}
int mod_evasive_plugin_init(plugin *p) {
p->version = LIGHTTPD_VERSION_ID;
p->name = buffer_init_string("evasive");
p->init = mod_evasive_init;
p->set_defaults = mod_evasive_set_defaults;
p->handle_uri_clean = mod_evasive_uri_handler;
p->cleanup = mod_evasive_free;
p->data = NULL;
return 0;
}
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