added mod_evasive to limit the number of connections by IP (<w1zzard@techpowerup.com>)

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-merge-1.4.x@896 152afb58-edef-0310-8abb-c4023f1b3aa9

src/mod_evasive.c

@@ -0,0 +1,174 @@
+#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 {
+	int 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];
+
+		if (c->dst_addr.ipv4.sin_addr.s_addr == con->dst_addr.ipv4.sin_addr.s_addr) {
+			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;
+}