GNUnet 0.21.2
gnunet-dns-redirector.c
Go to the documentation of this file.
1/*
2 This file is part of GNUnet.
3 Copyright (C) 2011 GNUnet e.V.
4
5 GNUnet is free software: you can redistribute it and/or modify it
6 under the terms of the GNU Affero General Public License as published
7 by the Free Software Foundation, either version 3 of the License,
8 or (at your option) any later version.
9
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Affero General Public License for more details.
14
15 You should have received a copy of the GNU Affero General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
17
18 SPDX-License-Identifier: AGPL3.0-or-later
19 */
20
27#include "platform.h"
28#include "gnunet_util_lib.h"
29#include "gnunet_dns_service.h"
30
35
39static char *n4;
40
44static char *n6;
45
49static int ret;
50
54static unsigned int verbosity;
55
56
62static void
64{
65 char buf[INET6_ADDRSTRLEN];
66
67 switch (record->type)
68 {
70 if (record->data.raw.data_len != sizeof(struct in_addr))
71 return;
72 if (NULL != n4)
73 {
74 if (verbosity > 1)
75 fprintf (stderr,
76 "Changing A record from `%s' to `%s'\n",
77 inet_ntop (AF_INET, record->data.raw.data, buf, sizeof(buf)),
78 n4);
79 GNUNET_assert (1 == inet_pton (AF_INET, n4, record->data.raw.data));
80 }
81 break;
82
84 if (record->data.raw.data_len != sizeof(struct in6_addr))
85 return;
86 if (NULL != n6)
87 {
88 if (verbosity > 1)
89 fprintf (stderr,
90 "Changing AAAA record from `%s' to `%s'\n",
91 inet_ntop (AF_INET6, record->data.raw.data, buf, sizeof(buf)),
92 n6);
93 GNUNET_assert (1 == inet_pton (AF_INET6, n6, record->data.raw.data));
94 }
95 break;
96
103 break;
104
105 default:
106 break;
107 }
108}
109
110
134static void
135modify_request (void *cls,
137 size_t request_length,
138 const char *request)
139{
141 unsigned int i;
142 char *buf;
143 size_t len;
144 int ret;
145
146 p = GNUNET_DNSPARSER_parse (request, request_length);
147 if (NULL == p)
148 {
149 fprintf (stderr, "Received malformed DNS packet, leaving it untouched\n");
151 return;
152 }
153 for (i = 0; i < p->num_answers; i++)
154 modify_record (&p->answers[i]);
155 buf = NULL;
156 ret = GNUNET_DNSPARSER_pack (p, 1024, &buf, &len);
158 if (GNUNET_OK != ret)
159 {
160 if (GNUNET_NO == ret)
161 fprintf (stderr,
162 "Modified DNS response did not fit, keeping old response\n");
163 else
164 GNUNET_break (0); /* our modifications should have been sane! */
166 }
167 else
168 {
169 if (verbosity > 0)
170 fprintf (stdout,
171 "Injecting modified DNS response\n");
172 GNUNET_DNS_request_answer (rh, len, buf);
173 }
174 GNUNET_free (buf);
175}
176
177
181static void
182do_disconnect (void *cls)
183{
184 if (NULL != handle)
185 {
187 handle = NULL;
188 }
189}
190
191
200static void
201run (void *cls, char *const *args, const char *cfgfile,
202 const struct GNUNET_CONFIGURATION_Handle *cfg)
203{
204 struct in_addr i4;
205 struct in6_addr i6;
206
207 if ((n4 != NULL) &&
208 (1 != inet_pton (AF_INET, n4, &i4)))
209 {
210 fprintf (stderr,
211 "`%s' is nto a valid IPv4 address!\n",
212 n4);
213 return;
214 }
215 if ((n6 != NULL) &&
216 (1 != inet_pton (AF_INET6, n6, &i6)))
217 {
218 fprintf (stderr,
219 "`%s' is nto a valid IPv6 address!\n",
220 n6);
221 return;
222 }
223
224 handle =
228 NULL);
230}
231
232
233int
234main (int argc, char *const *argv)
235{
238 "ipv4",
239 "IPV4",
240 gettext_noop ("set A records"),
241 &n4),
242
244 "ipv4",
245 "IPV6",
246 gettext_noop ("set AAAA records"),
247 &n6),
248
251 };
252
253 if (GNUNET_OK != GNUNET_STRINGS_get_utf8_args (argc, argv, &argc, &argv))
254 return 2;
255
256 ret = (GNUNET_OK ==
257 GNUNET_PROGRAM_run (argc, argv, "gnunet-dns-redirector",
259 ("Change DNS replies to point elsewhere."),
260 options,
261 &run, NULL)) ? ret : 1;
262 GNUNET_free_nz ((void *) argv);
263 return ret;
264}
265
266
267/* end of gnunet-dns-redirector.c */
struct GNUNET_GETOPT_CommandLineOption GNUNET_GETOPT_OPTION_END
Definition: 002.c:13
struct GNUNET_GETOPT_CommandLineOption options[]
Definition: 002.c:5
#define gettext_noop(String)
Definition: gettext.h:74
static struct GNUNET_CONFIGURATION_Handle * cfg
Our configuration.
Definition: gnunet-arm.c:109
static void record(void *cls, size_t data_size, const void *data)
Process recorded audio data.
static void do_disconnect(void *cls)
Shutdown.
static unsigned int verbosity
Selected level of verbosity.
static char * n4
New target for A records.
static char * n6
New target for AAAA records.
static void modify_request(void *cls, struct GNUNET_DNS_RequestHandle *rh, size_t request_length, const char *request)
Signature of a function that is called whenever the DNS service encounters a DNS request and needs to...
static void modify_record(const struct GNUNET_DNSPARSER_Record *record)
Modify the given DNS record.
static int ret
Global return value (0 success).
static void run(void *cls, char *const *args, const char *cfgfile, const struct GNUNET_CONFIGURATION_Handle *cfg)
Main function that will be run by the scheduler.
int main(int argc, char *const *argv)
static struct GNUNET_DNS_Handle * handle
Handle to DNS service.
static struct GNUNET_OS_Process * p
Helper process we started.
Definition: gnunet-uri.c:38
static struct GNUNET_VPN_RedirectionRequest * request
Opaque redirection request handle.
Definition: gnunet-vpn.c:40
API to access the DNS service.
void GNUNET_DNSPARSER_free_packet(struct GNUNET_DNSPARSER_Packet *p)
Free memory taken by a packet.
Definition: dnsparser.c:947
#define GNUNET_DNSPARSER_TYPE_SOA
#define GNUNET_DNSPARSER_TYPE_A
#define GNUNET_DNSPARSER_TYPE_PTR
#define GNUNET_DNSPARSER_TYPE_NS
#define GNUNET_DNSPARSER_TYPE_CNAME
#define GNUNET_DNSPARSER_TYPE_AAAA
int GNUNET_DNSPARSER_pack(const struct GNUNET_DNSPARSER_Packet *p, uint16_t max, char **buf, size_t *buf_length)
Given a DNS packet p, generate the corresponding UDP payload.
Definition: dnsparser.c:1392
#define GNUNET_DNSPARSER_TYPE_MX
#define GNUNET_DNSPARSER_TYPE_TXT
struct GNUNET_DNSPARSER_Packet * GNUNET_DNSPARSER_parse(const char *udp_payload, size_t udp_payload_length)
Parse a UDP payload of a DNS packet in to a nice struct for further processing and manipulation.
Definition: dnsparser.c:727
void GNUNET_DNS_disconnect(struct GNUNET_DNS_Handle *dh)
Disconnect from the DNS service.
Definition: dns_api.c:363
void GNUNET_DNS_request_forward(struct GNUNET_DNS_RequestHandle *rh)
If a GNUNET_DNS_RequestHandler calls this function, the client has no desire to interfer with the req...
Definition: dns_api.c:237
void GNUNET_DNS_request_answer(struct GNUNET_DNS_RequestHandle *rh, uint16_t reply_length, const char *reply)
If a GNUNET_DNS_RequestHandler calls this function, the request is supposed to be answered with the d...
Definition: dns_api.c:296
struct GNUNET_DNS_Handle * GNUNET_DNS_connect(const struct GNUNET_CONFIGURATION_Handle *cfg, enum GNUNET_DNS_Flags flags, GNUNET_DNS_RequestHandler rh, void *rh_cls)
Connect to the service-dns.
Definition: dns_api.c:340
@ GNUNET_DNS_FLAG_POST_RESOLUTION
This client wants to be called on the results of a DNS resolution (either resolved by PRE-RESOLUTION ...
struct GNUNET_GETOPT_CommandLineOption GNUNET_GETOPT_option_verbose(unsigned int *level)
Define the '-V' verbosity option.
struct GNUNET_GETOPT_CommandLineOption GNUNET_GETOPT_option_string(char shortName, const char *name, const char *argumentHelp, const char *description, char **str)
Allow user to specify a string.
@ GNUNET_OK
@ GNUNET_NO
#define GNUNET_assert(cond)
Use this for fatal errors that cannot be handled.
#define GNUNET_break(cond)
Use this for internal assertion violations that are not fatal (can be handled) but should not occur.
#define GNUNET_free(ptr)
Wrapper around free.
#define GNUNET_free_nz(ptr)
Wrapper around free.
enum GNUNET_GenericReturnValue GNUNET_PROGRAM_run(int argc, char *const *argv, const char *binaryName, const char *binaryHelp, const struct GNUNET_GETOPT_CommandLineOption *options, GNUNET_PROGRAM_Main task, void *task_cls)
Run a standard GNUnet command startup sequence (initialize loggers and configuration,...
Definition: program.c:400
struct GNUNET_SCHEDULER_Task * GNUNET_SCHEDULER_add_shutdown(GNUNET_SCHEDULER_TaskCallback task, void *task_cls)
Schedule a new task to be run on shutdown, that is when a CTRL-C signal is received,...
Definition: scheduler.c:1340
enum GNUNET_GenericReturnValue GNUNET_STRINGS_get_utf8_args(int argc, char *const *argv, int *u8argc, char *const **u8argv)
Returns utf-8 encoded arguments.
Definition: strings.c:1230
Easy-to-process, parsed version of a DNS packet.
A DNS response record.
DNS handle.
Definition: dns_api.c:57
GNUNET_DNS_RequestHandler rh
Function to call to get replies.
Definition: dns_api.c:71
Handle to identify an individual DNS request.
Definition: dns_api.c:35
Definition of a command line option.