1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
|
/*
This file is part of GNUnet.
(C) 2009 Christian Grothoff (and other contributing authors)
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3, or (at your
option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file vpn/gnunet-service-dns.c
* @author Philipp Tölke
*/
#include "platform.h"
#include "gnunet_getopt_lib.h"
#include "gnunet_service_lib.h"
#include "gnunet_network_lib.h"
#include "gnunet_os_lib.h"
#include "gnunet-service-dns-p.h"
#include "gnunet_protocols.h"
#include "gnunet-vpn-packet.h"
#include "gnunet-vpn-pretty-print.h"
#include "gnunet_container_lib.h"
#include "gnunet-dns-parser.h"
struct dns_cls {
struct GNUNET_SCHEDULER_Handle *sched;
struct GNUNET_NETWORK_Handle *dnsout;
unsigned short dnsoutport;
struct answer_packet_list *head;
struct answer_packet_list *tail;
};
static struct dns_cls mycls;
struct dns_query_id_state {
unsigned valid:1;
struct GNUNET_SERVER_Client* client;
unsigned local_ip:32;
unsigned local_port:16;
};
static struct dns_query_id_state query_states[65536]; /* This is < 1MiB */
void hijack(unsigned short port) {
char port_s[6];
GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Hijacking, port is %d\n", port);
snprintf(port_s, 6, "%d", port);
GNUNET_OS_start_process(NULL, NULL, "gnunet-helper-hijack-dns", "gnunet-hijack-dns", port_s, NULL);
}
void unhijack(unsigned short port) {
char port_s[6];
GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "unHijacking, port is %d\n", port);
snprintf(port_s, 6, "%d", port);
GNUNET_OS_start_process(NULL, NULL, "gnunet-helper-hijack-dns", "gnunet-hijack-dns", "-d", port_s, NULL);
}
/**
* This receives the dns-payload from the daemon-vpn and sends it on over the udp-socket
*/
void receive_query(void *cls, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message)
{
struct query_packet* pkt = (struct query_packet*)message;
struct dns_pkt* dns = (struct dns_pkt*)pkt->data;
struct dns_pkt_parsed* pdns = parse_dns_packet(dns);
if (pdns->queries[0]->namelen > 9 &&
0 == strncmp(pdns->queries[0]->name+(pdns->queries[0]->namelen - 9), ".gnunet.", 9)) {
GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Query for .gnunet!\n");
}
GNUNET_free(pdns);
struct sockaddr_in dest;
memset(&dest, 0, sizeof dest);
dest.sin_port = htons(53);
dest.sin_addr.s_addr = pkt->orig_to;
query_states[dns->s.id].valid = 1;
query_states[dns->s.id].client = client;
query_states[dns->s.id].local_ip = pkt->orig_from;
query_states[dns->s.id].local_port = pkt->src_port;
/* int r = */ GNUNET_NETWORK_socket_sendto(mycls.dnsout, dns, ntohs(pkt->hdr.size) - sizeof(struct query_packet) + 1, (struct sockaddr*) &dest, sizeof dest);
GNUNET_SERVER_receive_done(client, GNUNET_OK);
}
size_t send_answer(void* cls, size_t size, void* buf) {
struct answer_packet_list* query = mycls.head;
size_t len = ntohs(query->pkt.hdr.size);
GNUNET_assert(len <= size);
memcpy(buf, &query->pkt.hdr, len);
GNUNET_CONTAINER_DLL_remove (mycls.head, mycls.tail, query);
GNUNET_free(query);
if (mycls.head != NULL) {
GNUNET_SERVER_notify_transmit_ready(cls, ntohs(mycls.head->pkt.hdr.size), GNUNET_TIME_UNIT_FOREVER_REL, &send_answer, cls);
}
return len;
}
static void read_response (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc) {
unsigned char buf[65536];
struct dns_pkt* dns = (struct dns_pkt*)buf;
if (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)
return;
struct sockaddr_in addr;
memset(&addr, 0, sizeof addr);
unsigned int addrlen = sizeof addr;
int r;
r = GNUNET_NETWORK_socket_recvfrom(mycls.dnsout, buf, 65536, (struct sockaddr*)&addr, &addrlen);
/* if (r < 0) TODO */
if (query_states[dns->s.id].valid == 1) {
query_states[dns->s.id].valid = 0;
size_t len = sizeof(struct answer_packet) + r - 1; /* 1 for the unsigned char data[1]; */
struct answer_packet_list* answer = GNUNET_malloc(len + 2*sizeof(struct answer_packet_list*));
answer->pkt.hdr.type = htons(GNUNET_MESSAGE_TYPE_LOCAL_RESPONSE_DNS);
answer->pkt.hdr.size = htons(len);
answer->pkt.from = addr.sin_addr.s_addr;
answer->pkt.to = query_states[dns->s.id].local_ip;
answer->pkt.dst_port = query_states[dns->s.id].local_port;
memcpy(answer->pkt.data, buf, r);
GNUNET_CONTAINER_DLL_insert_after(mycls.head, mycls.tail, mycls.tail, answer);
/* struct GNUNET_CONNECTION_TransmitHandle* th = */ GNUNET_SERVER_notify_transmit_ready(query_states[dns->s.id].client, len, GNUNET_TIME_UNIT_FOREVER_REL, &send_answer, query_states[dns->s.id].client);
}
GNUNET_SCHEDULER_add_read_net(mycls.sched, GNUNET_TIME_UNIT_FOREVER_REL, mycls.dnsout, &read_response, NULL);
}
/**
* Task run during shutdown.
*
* @param cls unused
* @param tc unused
*/
static void
cleanup_task (void *cls,
const struct GNUNET_SCHEDULER_TaskContext *tc)
{
unhijack(mycls.dnsoutport);
}
/**
* @param cls closure
* @param sched scheduler to use
* @param server the initialized server
* @param cfg configuration to use
*/
static void
run (void *cls,
struct GNUNET_SCHEDULER_Handle *sched,
struct GNUNET_SERVER_Handle *server,
const struct GNUNET_CONFIGURATION_Handle *cfg)
{
static const struct GNUNET_SERVER_MessageHandler handlers[] = {
/* callback, cls, type, size */
{&receive_query, NULL, GNUNET_MESSAGE_TYPE_LOCAL_QUERY_DNS, 0},
{NULL, NULL, 0, 0}
};
{
int i;
for (i = 0; i < 65536; i++) {
query_states[i].valid = 0;
}
}
struct sockaddr_in addr;
mycls.sched = sched;
mycls.dnsout = GNUNET_NETWORK_socket_create (AF_INET, SOCK_DGRAM, 0);
if (mycls.dnsout == NULL)
return;
memset(&addr, 0, sizeof(struct sockaddr_in));
int err = GNUNET_NETWORK_socket_bind (mycls.dnsout,
(struct sockaddr*)&addr,
sizeof(struct sockaddr_in));
if (err != GNUNET_YES) {
GNUNET_log(GNUNET_ERROR_TYPE_ERROR, "Could not bind a port, exiting\n");
return;
}
socklen_t addrlen = sizeof(struct sockaddr_in);
err = getsockname(GNUNET_NETWORK_get_fd(mycls.dnsout),
(struct sockaddr*) &addr,
&addrlen);
mycls.dnsoutport = htons(addr.sin_port);
hijack(htons(addr.sin_port));
GNUNET_SCHEDULER_add_read_net(sched, GNUNET_TIME_UNIT_FOREVER_REL, mycls.dnsout, &read_response, NULL);
GNUNET_SERVER_add_handlers (server, handlers);
GNUNET_SCHEDULER_add_delayed (sched,
GNUNET_TIME_UNIT_FOREVER_REL,
&cleanup_task,
cls);
}
/**
* The main function for the dns service.
*
* @param argc number of arguments from the command line
* @param argv command line arguments
* @return 0 ok, 1 on error
*/
int
main (int argc, char *const *argv)
{
return (GNUNET_OK ==
GNUNET_SERVICE_run (argc,
argv,
"dns",
GNUNET_SERVICE_OPTION_NONE,
&run, NULL)) ? 0 : 1;
}
|
