1: #include "first.h"
2:
3: #include "base.h"
4: #include "log.h"
5: #include "buffer.h"
6: #include "response.h"
7:
8: #include "plugin.h"
9:
10: #include "inet_ntop_cache.h"
11:
12: #include <ctype.h>
13: #include <stdlib.h>
14: #include <string.h>
15:
16: /**
17: * mod_evasive
18: *
19: * we indent to implement all features the mod_evasive from apache has
20: *
21: * - limit of connections per IP
22: * - provide a list of block-listed ip/networks (no access)
23: * - provide a white-list of ips/network which is not affected by the limit
24: * (hmm, conditionals might be enough)
25: * - provide a bandwidth limiter per IP
26: *
27: * started by:
28: * - w1zzard@techpowerup.com
29: */
30:
31: typedef struct {
32: unsigned short max_conns;
33: unsigned short silent;
34: buffer *location;
35: } plugin_config;
36:
37: typedef struct {
38: PLUGIN_DATA;
39:
40: plugin_config **config_storage;
41:
42: plugin_config conf;
43: } plugin_data;
44:
45: INIT_FUNC(mod_evasive_init) {
46: plugin_data *p;
47:
48: p = calloc(1, sizeof(*p));
49:
50: return p;
51: }
52:
53: FREE_FUNC(mod_evasive_free) {
54: plugin_data *p = p_d;
55:
56: UNUSED(srv);
57:
58: if (!p) return HANDLER_GO_ON;
59:
60: if (p->config_storage) {
61: size_t i;
62: for (i = 0; i < srv->config_context->used; i++) {
63: plugin_config *s = p->config_storage[i];
64:
65: if (NULL == s) continue;
66:
67: buffer_free(s->location);
68:
69: free(s);
70: }
71: free(p->config_storage);
72: }
73:
74: free(p);
75:
76: return HANDLER_GO_ON;
77: }
78:
79: SETDEFAULTS_FUNC(mod_evasive_set_defaults) {
80: plugin_data *p = p_d;
81: size_t i = 0;
82:
83: config_values_t cv[] = {
84: { "evasive.max-conns-per-ip", NULL, T_CONFIG_SHORT, T_CONFIG_SCOPE_CONNECTION }, /* 0 */
85: { "evasive.silent", NULL, T_CONFIG_BOOLEAN, T_CONFIG_SCOPE_CONNECTION }, /* 1 */
86: { "evasive.location", NULL, T_CONFIG_STRING, T_CONFIG_SCOPE_CONNECTION }, /* 2 */
87: { NULL, NULL, T_CONFIG_UNSET, T_CONFIG_SCOPE_UNSET }
88: };
89:
90: p->config_storage = calloc(1, srv->config_context->used * sizeof(plugin_config *));
91:
92: for (i = 0; i < srv->config_context->used; i++) {
93: data_config const* config = (data_config const*)srv->config_context->data[i];
94: plugin_config *s;
95:
96: s = calloc(1, sizeof(plugin_config));
97: s->max_conns = 0;
98: s->silent = 0;
99: s->location = buffer_init();
100:
101: cv[0].destination = &(s->max_conns);
102: cv[1].destination = &(s->silent);
103: cv[2].destination = s->location;
104:
105: p->config_storage[i] = s;
106:
107: if (0 != config_insert_values_global(srv, config->value, cv, i == 0 ? T_CONFIG_SCOPE_SERVER : T_CONFIG_SCOPE_CONNECTION)) {
108: return HANDLER_ERROR;
109: }
110: }
111:
112: return HANDLER_GO_ON;
113: }
114:
115: #define PATCH(x) \
116: p->conf.x = s->x;
117: static int mod_evasive_patch_connection(server *srv, connection *con, plugin_data *p) {
118: size_t i, j;
119: plugin_config *s = p->config_storage[0];
120:
121: PATCH(max_conns);
122: PATCH(silent);
123: PATCH(location);
124:
125: /* skip the first, the global context */
126: for (i = 1; i < srv->config_context->used; i++) {
127: data_config *dc = (data_config *)srv->config_context->data[i];
128: s = p->config_storage[i];
129:
130: /* condition didn't match */
131: if (!config_check_cond(srv, con, dc)) continue;
132:
133: /* merge config */
134: for (j = 0; j < dc->value->used; j++) {
135: data_unset *du = dc->value->data[j];
136:
137: if (buffer_is_equal_string(du->key, CONST_STR_LEN("evasive.max-conns-per-ip"))) {
138: PATCH(max_conns);
139: } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("evasive.silent"))) {
140: PATCH(silent);
141: } else if (buffer_is_equal_string(du->key, CONST_STR_LEN("evasive.location"))) {
142: PATCH(location);
143: }
144: }
145: }
146:
147: return 0;
148: }
149: #undef PATCH
150:
151: URIHANDLER_FUNC(mod_evasive_uri_handler) {
152: plugin_data *p = p_d;
153: size_t conns_by_ip = 0;
154: size_t j;
155:
156: if (buffer_is_empty(con->uri.path)) return HANDLER_GO_ON;
157:
158: mod_evasive_patch_connection(srv, con, p);
159:
160: /* no limit set, nothing to block */
161: if (p->conf.max_conns == 0) return HANDLER_GO_ON;
162:
163: switch (con->dst_addr.plain.sa_family) {
164: case AF_INET:
165: #ifdef HAVE_IPV6
166: case AF_INET6:
167: #endif
168: break;
169: default: /* Address family not supported */
170: return HANDLER_GO_ON;
171: };
172:
173: for (j = 0; j < srv->conns->used; j++) {
174: connection *c = srv->conns->ptr[j];
175:
176: /* check if other connections are already actively serving data for the same IP
177: * we can only ban connections which are already behind the 'read request' state
178: * */
179: if (c->dst_addr.plain.sa_family != con->dst_addr.plain.sa_family) continue;
180: if (c->state <= CON_STATE_REQUEST_END) continue;
181:
182: switch (con->dst_addr.plain.sa_family) {
183: case AF_INET:
184: if (c->dst_addr.ipv4.sin_addr.s_addr != con->dst_addr.ipv4.sin_addr.s_addr) continue;
185: break;
186: #ifdef HAVE_IPV6
187: case AF_INET6:
188: if (0 != memcmp(c->dst_addr.ipv6.sin6_addr.s6_addr, con->dst_addr.ipv6.sin6_addr.s6_addr, 16)) continue;
189: break;
190: #endif
191: default: /* Address family not supported, should never be reached */
192: continue;
193: };
194: conns_by_ip++;
195:
196: if (conns_by_ip > p->conf.max_conns) {
197: if (!p->conf.silent) {
198: log_error_write(srv, __FILE__, __LINE__, "ss",
199: inet_ntop_cache_get_ip(srv, &(con->dst_addr)),
200: "turned away. Too many connections.");
201: }
202:
203: if (!buffer_is_empty(p->conf.location)) {
204: response_header_overwrite(srv, con, CONST_STR_LEN("Location"), CONST_BUF_LEN(p->conf.location));
205: con->http_status = 302;
206: con->file_finished = 1;
207: } else {
208: con->http_status = 403;
209: }
210: con->mode = DIRECT;
211: return HANDLER_FINISHED;
212: }
213: }
214:
215: return HANDLER_GO_ON;
216: }
217:
218:
219: int mod_evasive_plugin_init(plugin *p);
220: int mod_evasive_plugin_init(plugin *p) {
221: p->version = LIGHTTPD_VERSION_ID;
222: p->name = buffer_init_string("evasive");
223:
224: p->init = mod_evasive_init;
225: p->set_defaults = mod_evasive_set_defaults;
226: p->handle_uri_clean = mod_evasive_uri_handler;
227: p->cleanup = mod_evasive_free;
228:
229: p->data = NULL;
230:
231: return 0;
232: }
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