Move repeating MIN/MAX macros into dropin.h.
[tinc] / src / protocol.c
1 /*
2     protocol.c -- handle the meta-protocol, basic functions
3     Copyright (C) 1999-2005 Ivo Timmermans,
4                   2000-2013 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 "xalloc.h"
29
30 bool tunnelserver = false;
31 bool strictsubnets = false;
32 bool experimental = true;
33
34 /* Jumptable for the request handlers */
35
36 static bool (*request_handlers[])(connection_t *, const char *) = {
37         id_h, metakey_h, challenge_h, chal_reply_h, ack_h,
38         NULL, NULL, termreq_h,
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, control_h,
43         NULL, NULL, /* Not "real" requests (yet) */
44         sptps_tcppacket_h,
45         udp_info_h, mtu_info_h,
46 };
47
48 /* Request names */
49
50 static char (*request_name[]) = {
51         "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "ACK",
52         "STATUS", "ERROR", "TERMREQ",
53         "PING", "PONG",
54         "ADD_SUBNET", "DEL_SUBNET",
55         "ADD_EDGE", "DEL_EDGE", "KEY_CHANGED", "REQ_KEY", "ANS_KEY", "PACKET", "CONTROL",
56         "REQ_PUBKEY", "ANS_PUBKEY", "SPTPS_PACKET", "UDP_INFO", "MTU_INFO",
57 };
58
59 static int past_request_compare(const past_request_t *a, const past_request_t *b) {
60         return strcmp(a->request, b->request);
61 }
62
63 static void free_past_request(past_request_t *r) {
64         free((char *)r->request);
65         free(r);
66 }
67
68 static splay_tree_t past_request_tree = {
69         .compare = (splay_compare_t) past_request_compare,
70         .delete = (splay_action_t) free_past_request,
71 };
72
73 /* Generic request routines - takes care of logging and error
74    detection as well */
75
76 bool send_request(connection_t *c, const char *format, ...) {
77         va_list args;
78         char request[MAXBUFSIZE];
79         int len;
80
81         /* Use vsnprintf instead of vxasprintf: faster, no memory
82            fragmentation, cleanup is automatic, and there is a limit on the
83            input buffer anyway */
84
85         va_start(args, format);
86         len = vsnprintf(request, sizeof(request), format, args);
87         request[sizeof(request) - 1] = 0;
88         va_end(args);
89
90         if(len < 0 || (size_t)len > sizeof(request) - 1) {
91                 logger(DEBUG_ALWAYS, LOG_ERR, "Output buffer overflow while sending request to %s (%s)",
92                        c->name, c->hostname);
93                 return false;
94         }
95
96         int id = atoi(request);
97         logger(DEBUG_META, LOG_DEBUG, "Sending %s to %s (%s): %s", request_name[id], c->name, c->hostname, request);
98
99         request[len++] = '\n';
100
101         if(c == everyone) {
102                 broadcast_meta(NULL, request, len);
103                 return true;
104         } else {
105                 if(id) {
106                         return send_meta(c, request, len);
107                 } else {
108                         send_meta_raw(c, request, len);
109                         return true;
110                 }
111         }
112 }
113
114 void forward_request(connection_t *from, const char *request) {
115         logger(DEBUG_META, LOG_DEBUG, "Forwarding %s from %s (%s): %s", request_name[atoi(request)], from->name, from->hostname, request);
116
117         // Create a temporary newline-terminated copy of the request
118         size_t len = strlen(request);
119         char tmp[len + 1];
120         memcpy(tmp, request, len);
121         tmp[len] = '\n';
122         broadcast_meta(from, tmp, sizeof(tmp));
123 }
124
125 bool receive_request(connection_t *c, const char *request) {
126         if(c->outgoing && proxytype == PROXY_HTTP && c->allow_request == ID) {
127                 if(!request[0] || request[0] == '\r') {
128                         return true;
129                 }
130
131                 if(!strncasecmp(request, "HTTP/1.1 ", 9)) {
132                         if(!strncmp(request + 9, "200", 3)) {
133                                 logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Proxy request granted");
134                                 return true;
135                         } else {
136                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "Proxy request rejected: %s", request + 9);
137                                 return false;
138                         }
139                 }
140         }
141
142         int reqno = atoi(request);
143
144         if(reqno || *request == '0') {
145                 if((reqno < 0) || (reqno >= LAST) || !request_handlers[reqno]) {
146                         logger(DEBUG_META, LOG_DEBUG, "Unknown request from %s (%s): %s", c->name, c->hostname, request);
147                         return false;
148                 } else {
149                         logger(DEBUG_META, LOG_DEBUG, "Got %s from %s (%s): %s", request_name[reqno], c->name, c->hostname, request);
150                 }
151
152                 if((c->allow_request != ALL) && (c->allow_request != reqno)) {
153                         logger(DEBUG_ALWAYS, LOG_ERR, "Unauthorized request from %s (%s)", c->name, c->hostname);
154                         return false;
155                 }
156
157                 if(!request_handlers[reqno](c, request)) {
158                         /* Something went wrong. Probably scriptkiddies. Terminate. */
159
160                         if(reqno != TERMREQ) {
161                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while processing %s from %s (%s)", request_name[reqno], c->name, c->hostname);
162                         }
163
164                         return false;
165                 }
166         } else {
167                 logger(DEBUG_ALWAYS, LOG_ERR, "Bogus data received from %s (%s)", c->name, c->hostname);
168                 return false;
169         }
170
171         return true;
172 }
173
174 static timeout_t past_request_timeout;
175
176 static void age_past_requests(void *data) {
177         (void)data;
178         int left = 0, deleted = 0;
179
180         for splay_each(past_request_t, p, &past_request_tree) {
181                 if(p->firstseen + pinginterval <= now.tv_sec) {
182                         splay_delete_node(&past_request_tree, node), deleted++;
183                 } else {
184                         left++;
185                 }
186         }
187
188         if(left || deleted) {
189                 logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Aging past requests: deleted %d, left %d", deleted, left);
190         }
191
192         if(left)
193                 timeout_set(&past_request_timeout, &(struct timeval) {
194                 10, rand() % 100000
195         });
196 }
197
198 bool seen_request(const char *request) {
199         past_request_t *new, p = {0};
200
201         p.request = request;
202
203         if(splay_search(&past_request_tree, &p)) {
204                 logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Already seen request");
205                 return true;
206         } else {
207                 new = xmalloc(sizeof(*new));
208                 new->request = xstrdup(request);
209                 new->firstseen = now.tv_sec;
210                 splay_insert(&past_request_tree, new);
211                 timeout_add(&past_request_timeout, age_past_requests, NULL, &(struct timeval) {
212                         10, rand() % 100000
213                 });
214                 return false;
215         }
216 }
217
218 void exit_requests(void) {
219         splay_empty_tree(&past_request_tree);
220
221         timeout_del(&past_request_timeout);
222 }