1 /*
2 protocol.c -- handle the meta-protocol, basic functions
3 Copyright (C) 1999-2005 Ivo Timmermans,
4 2000-2016 Guus Sliepen <guus@tinc-vpn.org>
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License along
17 with this program; if not, write to the Free Software Foundation, Inc.,
18 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
19 */
20
21 #include "system.h"
22
23 #include "conf.h"
24 #include "connection.h"
25 #include "logger.h"
26 #include "meta.h"
27 #include "protocol.h"
28 #include "utils.h"
29 #include "xalloc.h"
30
31 bool tunnelserver = false;
32 bool strictsubnets = false;
33
34 /* Jumptable for the request handlers */
35
36 static bool (*request_handlers[])(connection_t *) = {
37 id_h, metakey_h, challenge_h, chal_reply_h, ack_h,
38 NULL, NULL, NULL,
39 ping_h, pong_h,
40 add_subnet_h, del_subnet_h,
41 add_edge_h, del_edge_h,
42 key_changed_h, req_key_h, ans_key_h, tcppacket_h,
43 };
44
45 /* Request names */
46
47 static char (*request_name[]) = {
48 "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
49 "STATUS", "ERROR", "TERMREQ",
50 "PING", "PONG",
51 "ADD_SUBNET", "DEL_SUBNET",
52 "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET",
53 };
54
55 static avl_tree_t *past_request_tree;
56
check_id(const char * id)57 bool check_id(const char *id) {
58 for(; *id; id++)
59 if(!isalnum(*id) && *id != '_') {
60 return false;
61 }
62
63 return true;
64 }
65
66 /* Generic request routines - takes care of logging and error
67 detection as well */
68
send_request(connection_t * c,const char * format,...)69 bool send_request(connection_t *c, const char *format, ...) {
70 va_list args;
71 char buffer[MAXBUFSIZE];
72 int len, request = 0;
73
74 /* Use vsnprintf instead of vxasprintf: faster, no memory
75 fragmentation, cleanup is automatic, and there is a limit on the
76 input buffer anyway */
77
78 va_start(args, format);
79 len = vsnprintf(buffer, sizeof(buffer), format, args);
80 buffer[sizeof(buffer) - 1] = 0;
81 va_end(args);
82
83 if(len < 0 || (size_t)len > sizeof(buffer) - 1) {
84 logger(LOG_ERR, "Output buffer overflow while sending request to %s (%s)",
85 c->name, c->hostname);
86 return false;
87 }
88
89 ifdebug(PROTOCOL) {
90 sscanf(buffer, "%d", &request);
91 ifdebug(META)
92 logger(LOG_DEBUG, "Sending %s to %s (%s): %s",
93 request_name[request], c->name, c->hostname, buffer);
94 else
95 logger(LOG_DEBUG, "Sending %s to %s (%s)", request_name[request],
96 c->name, c->hostname);
97 }
98
99 buffer[len++] = '\n';
100
101 if(c == everyone) {
102 broadcast_meta(NULL, buffer, len);
103 return true;
104 } else {
105 return send_meta(c, buffer, len);
106 }
107 }
108
forward_request(connection_t * from)109 void forward_request(connection_t *from) {
110 int request;
111
112 ifdebug(PROTOCOL) {
113 sscanf(from->buffer, "%d", &request);
114 ifdebug(META)
115 logger(LOG_DEBUG, "Forwarding %s from %s (%s): %s",
116 request_name[request], from->name, from->hostname,
117 from->buffer);
118 else
119 logger(LOG_DEBUG, "Forwarding %s from %s (%s)",
120 request_name[request], from->name, from->hostname);
121 }
122
123 from->buffer[from->reqlen - 1] = '\n';
124
125 broadcast_meta(from, from->buffer, from->reqlen);
126 }
127
receive_request(connection_t * c)128 bool receive_request(connection_t *c) {
129 int request;
130
131 if(sscanf(c->buffer, "%d", &request) == 1) {
132 if((request < 0) || (request >= LAST) || !request_handlers[request]) {
133 ifdebug(META)
134 logger(LOG_DEBUG, "Unknown request from %s (%s): %s",
135 c->name, c->hostname, c->buffer);
136 else
137 logger(LOG_ERR, "Unknown request from %s (%s)",
138 c->name, c->hostname);
139
140 return false;
141 } else {
142 ifdebug(PROTOCOL) {
143 ifdebug(META)
144 logger(LOG_DEBUG, "Got %s from %s (%s): %s",
145 request_name[request], c->name, c->hostname,
146 c->buffer);
147 else
148 logger(LOG_DEBUG, "Got %s from %s (%s)",
149 request_name[request], c->name, c->hostname);
150 }
151 }
152
153 if((c->allow_request != ALL) && (c->allow_request != request)) {
154 logger(LOG_ERR, "Unauthorized request from %s (%s)", c->name,
155 c->hostname);
156 return false;
157 }
158
159 if(!request_handlers[request](c)) {
160 /* Something went wrong. Probably scriptkiddies. Terminate. */
161
162 logger(LOG_ERR, "Error while processing %s from %s (%s)",
163 request_name[request], c->name, c->hostname);
164 return false;
165 }
166 } else {
167 logger(LOG_ERR, "Bogus data received from %s (%s)",
168 c->name, c->hostname);
169 return false;
170 }
171
172 return true;
173 }
174
past_request_compare(const past_request_t * a,const past_request_t * b)175 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
176 return strcmp(a->request, b->request);
177 }
178
free_past_request(past_request_t * r)179 static void free_past_request(past_request_t *r) {
180 if(r->request) {
181 free(r->request);
182 }
183
184 free(r);
185 }
186
init_requests(void)187 void init_requests(void) {
188 past_request_tree = avl_alloc_tree((avl_compare_t) past_request_compare, (avl_action_t) free_past_request);
189 }
190
exit_requests(void)191 void exit_requests(void) {
192 avl_delete_tree(past_request_tree);
193 }
194
seen_request(char * request)195 bool seen_request(char *request) {
196 past_request_t *new, p = {0};
197
198 p.request = request;
199
200 if(avl_search(past_request_tree, &p)) {
201 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Already seen request");
202 return true;
203 } else {
204 new = xmalloc(sizeof(*new));
205 new->request = xstrdup(request);
206 new->firstseen = now;
207 avl_insert(past_request_tree, new);
208 return false;
209 }
210 }
211
age_past_requests(void)212 void age_past_requests(void) {
213 avl_node_t *node, *next;
214 past_request_t *p;
215 int left = 0, deleted = 0;
216
217 for(node = past_request_tree->head; node; node = next) {
218 next = node->next;
219 p = node->data;
220
221 if(p->firstseen + pinginterval <= now) {
222 avl_delete_node(past_request_tree, node), deleted++;
223 } else {
224 left++;
225 }
226 }
227
228 if(left || deleted)
229 ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Aging past requests: deleted %d, left %d",
230 deleted, left);
231 }
232