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gnunet-service-gns_interceptor.c File Reference

GNUnet GNS interceptor logic. More...

Include dependency graph for gnunet-service-gns_interceptor.c:

Go to the source code of this file.

Data Structures

struct  InterceptLookupHandle
 Handle to a DNS intercepted reslution request. More...
 

Macros

#define MAX_RECURSION   256
 How deep do we allow recursions to go before we abort? More...
 

Functions

static void reply_to_dns (void *cls, uint32_t rd_count, const struct GNUNET_GNSRECORD_Data *rd)
 Reply to dns request with the result from our lookup. More...
 
static void handle_dns_request (void *cls, struct GNUNET_DNS_RequestHandle *rh, size_t request_length, const char *request)
 The DNS request handler. More...
 
int GNS_interceptor_init (const struct GNUNET_CONFIGURATION_Handle *c)
 Initialize DNS interceptor. More...
 
void GNS_interceptor_done ()
 Disconnect from interceptor. More...
 

Variables

static struct GNUNET_DNS_Handledns_handle
 Our handle to the DNS handler library. More...
 
static struct InterceptLookupHandleilh_head
 Head of the DLL. More...
 
static struct InterceptLookupHandleilh_tail
 Tail of the DLL. More...
 

Detailed Description

GNUnet GNS interceptor logic.

Author
Martin Schanzenbach
Christian Grothoff

Definition in file gnunet-service-gns_interceptor.c.

Macro Definition Documentation

◆ MAX_RECURSION

#define MAX_RECURSION   256

How deep do we allow recursions to go before we abort?

Definition at line 38 of file gnunet-service-gns_interceptor.c.

Function Documentation

◆ reply_to_dns()

static void reply_to_dns ( void *  cls,
uint32_t  rd_count,
const struct GNUNET_GNSRECORD_Data rd 
)
static

Reply to dns request with the result from our lookup.

Parameters
clsthe closure to the request (an InterceptLookupHandle)
rd_countthe number of records to return
rdthe record data

Definition at line 98 of file gnunet-service-gns_interceptor.c.

100 {
101  struct InterceptLookupHandle *ilh = cls;
102  struct GNUNET_DNSPARSER_Packet *packet = ilh->packet;
103  struct GNUNET_DNSPARSER_Query *query = &packet->queries[0];
104  uint32_t i;
105  size_t len;
106  int ret;
107  char *buf;
108  unsigned int num_answers;
109  unsigned int skip_answers;
110  unsigned int skip_additional;
111  size_t off = 0;
112 
113  /* Put records in the DNS packet */
114  num_answers = 0;
115  for (i = 0; i < rd_count; i++)
116  if (rd[i].record_type == query->type)
117  num_answers++;
118  skip_answers = 0;
119  skip_additional = 0;
120 
121  {
122  struct GNUNET_DNSPARSER_Record answer_records[num_answers];
123  struct GNUNET_DNSPARSER_Record additional_records[rd_count - num_answers];
124 
125  packet->answers = answer_records;
126  packet->additional_records = additional_records;
127  /* FIXME: need to handle #GNUNET_GNSRECORD_RF_SHADOW_RECORD option
128  (by ignoring records where this flag is set if there is any
129  other record of that type in the result set) */
130  for (i = 0; i < rd_count; i++)
131  {
132  if (rd[i].record_type == query->type)
133  {
134  answer_records[i - skip_answers].name = query->name;
135  answer_records[i - skip_answers].type = rd[i].record_type;
136  switch (rd[i].record_type)
137  {
141  answer_records[i - skip_answers].data.hostname
143  rd[i].data_size,
144  &off);
145  if ((off != rd[i].data_size) ||
146  (NULL == answer_records[i].data.hostname))
147  {
148  GNUNET_break_op (0);
149  skip_answers++;
150  }
151  break;
152 
154  answer_records[i - skip_answers].data.soa
156  rd[i].data_size,
157  &off);
158  if ((off != rd[i].data_size) ||
159  (NULL == answer_records[i].data.soa))
160  {
161  GNUNET_break_op (0);
162  skip_answers++;
163  }
164  break;
165 
167  /* FIXME: SRV is not yet supported */
168  skip_answers++;
169  break;
170 
172  /* FIXME: URI is not yet supported */
173  skip_answers++;
174  break;
175 
177  answer_records[i - skip_answers].data.mx
179  rd[i].data_size,
180  &off);
181  if ((off != rd[i].data_size) ||
182  (NULL == answer_records[i].data.hostname))
183  {
184  GNUNET_break_op (0);
185  skip_answers++;
186  }
187  break;
188 
189  default:
190  answer_records[i - skip_answers].data.raw.data_len = rd[i].data_size;
191  answer_records[i - skip_answers].data.raw.data = (char *) rd[i].data;
192  break;
193  }
194  GNUNET_break (0 == (rd[i - skip_answers].flags
196  answer_records[i - skip_answers].expiration_time.abs_value_us =
197  rd[i].expiration_time;
198  answer_records[i - skip_answers].dns_traffic_class =
200  }
201  else
202  {
203  additional_records[i - skip_additional].name = query->name;
204  additional_records[i - skip_additional].type = rd[i].record_type;
205  switch (rd[i].record_type)
206  {
210  additional_records[i - skip_additional].data.hostname
212  rd[i].data_size,
213  &off);
214  if ((off != rd[i].data_size) ||
215  (NULL == additional_records[i].data.hostname))
216  {
217  GNUNET_break_op (0);
218  skip_additional++;
219  }
220  break;
221 
223  additional_records[i - skip_additional].data.soa
225  rd[i].data_size,
226  &off);
227  if ((off != rd[i].data_size) ||
228  (NULL == additional_records[i].data.hostname))
229  {
230  GNUNET_break_op (0);
231  skip_additional++;
232  }
233  break;
234 
236  additional_records[i - skip_additional].data.mx
238  rd[i].data_size,
239  &off);
240  if ((off != rd[i].data_size) ||
241  (NULL == additional_records[i].data.hostname))
242  {
243  GNUNET_break_op (0);
244  skip_additional++;
245  }
246  break;
247 
249  /* FIXME: SRV is not yet supported */
250  skip_answers++;
251  break;
252 
254  additional_records[i - skip_additional].data.uri
256  rd[i].data_size,
257  &off);
258  if ((off != rd[i].data_size) ||
259  (NULL == additional_records[i].data.uri))
260  {
261  GNUNET_break_op (0);
262  skip_additional++;
263  }
264  break;
265 
266  default:
267  additional_records[i - skip_additional].data.raw.data_len =
268  rd[i].data_size;
269  additional_records[i - skip_additional].data.raw.data =
270  (char *) rd[i].data;
271  break;
272  }
273  GNUNET_break (0 == (rd[i - skip_additional].flags
275  additional_records[i - skip_additional].expiration_time.abs_value_us =
276  rd[i].expiration_time;
277  additional_records[i - skip_additional].dns_traffic_class =
279  }
280  }
281  packet->num_answers = num_answers - skip_answers;
282  packet->num_additional_records = rd_count - num_answers - skip_additional;
283  packet->flags.authoritative_answer = 1;
284  if (NULL == rd)
286  else
288  packet->flags.query_or_response = 1;
289  ret = GNUNET_DNSPARSER_pack (packet,
290  1024, /* maximum allowed size for DNS reply */
291  &buf,
292  &len);
293  if (GNUNET_OK != ret)
294  {
296  _ ("Error converting GNS response to DNS response!\n"));
297  if (GNUNET_NO == ret)
298  GNUNET_free (buf);
299  }
300  else
301  {
303  len,
304  buf);
305  GNUNET_free (buf);
306  }
307  packet->num_answers = 0;
308  packet->answers = NULL;
309  packet->num_additional_records = 0;
310  packet->additional_records = NULL;
312  }
314  GNUNET_free (ilh);
315 }
static int ret
Final status code.
Definition: gnunet-arm.c:94
static char * data
The data to insert into the dht.
static unsigned int rd_count
Number of records for currently parsed set.
static struct GNUNET_GNSRECORD_Data rd[50]
The record data under a single label.
static size_t data_size
Number of bytes in data.
static struct InterceptLookupHandle * ilh_head
Head of the DLL.
static struct InterceptLookupHandle * ilh_tail
Tail of the DLL.
#define GNUNET_CONTAINER_DLL_remove(head, tail, element)
Remove an element from a DLL.
#define GNUNET_DNSPARSER_TYPE_URI
struct GNUNET_DNSPARSER_SoaRecord * GNUNET_DNSPARSER_parse_soa(const char *udp_payload, size_t udp_payload_length, size_t *off)
Parse a DNS SOA record.
Definition: dnsparser.c:410
void GNUNET_DNSPARSER_free_packet(struct GNUNET_DNSPARSER_Packet *p)
Free memory taken by a packet.
Definition: dnsparser.c:945
struct GNUNET_DNSPARSER_UriRecord * GNUNET_DNSPARSER_parse_uri(const char *udp_payload, size_t udp_payload_length, size_t *off)
Parse a DNS URI record.
Definition: dnsparser.c:537
#define GNUNET_DNSPARSER_TYPE_SRV
#define GNUNET_DNSPARSER_TYPE_SOA
#define GNUNET_DNSPARSER_TYPE_PTR
struct GNUNET_DNSPARSER_MxRecord * GNUNET_DNSPARSER_parse_mx(const char *udp_payload, size_t udp_payload_length, size_t *off)
Parse a DNS MX record.
Definition: dnsparser.c:455
#define GNUNET_DNSPARSER_TYPE_NS
#define GNUNET_DNSPARSER_TYPE_CNAME
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:1389
#define GNUNET_DNSPARSER_TYPE_MX
char * GNUNET_DNSPARSER_parse_name(const char *udp_payload, size_t udp_payload_length, size_t *off)
Parse name inside of a DNS query or record.
Definition: dnsparser.c:353
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
@ GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION
This expiration time of the record is a relative time (not an absolute time).
#define GNUNET_log(kind,...)
@ GNUNET_OK
@ GNUNET_NO
#define GNUNET_break_op(cond)
Use this for assertion violations caused by other peers (i.e.
#define GNUNET_break(cond)
Use this for internal assertion violations that are not fatal (can be handled) but should not occur.
@ GNUNET_ERROR_TYPE_WARNING
#define GNUNET_free(ptr)
Wrapper around free.
#define GNUNET_TUN_DNS_RETURN_CODE_NAME_ERROR
#define GNUNET_TUN_DNS_CLASS_INTERNET
A few common DNS classes (ok, only one is common, but I list a couple more to make it clear what we'r...
#define GNUNET_TUN_DNS_RETURN_CODE_NO_ERROR
RFC 1035 codes.
#define _(String)
GNU gettext support macro.
Definition: platform.h:178
Easy-to-process, parsed version of a DNS packet.
struct GNUNET_DNSPARSER_Query * queries
Array of all queries in the packet, must contain "num_queries" entries.
unsigned int num_answers
Number of answers in the packet, should be 0 for queries.
struct GNUNET_TUN_DnsFlags flags
Bitfield of DNS flags.
struct GNUNET_DNSPARSER_Record * answers
Array of all answers in the packet, must contain "num_answers" entries.
unsigned int num_additional_records
Number of additional records in the packet, should be 0 for queries.
struct GNUNET_DNSPARSER_Record * additional_records
Array of all additional answers in the packet, must contain "num_additional_records" entries.
uint16_t type
See GNUNET_DNSPARSER_TYPE_*.
char * name
Name of the record that the query is for (0-terminated).
A DNS response record.
char * name
Name of the record that the query is for (0-terminated).
uint32_t record_type
Type of the GNS/DNS record.
size_t data_size
Number of bytes in data.
uint64_t expiration_time
Expiration time for the DNS record.
unsigned int query_or_response
query:0, response:1
unsigned int return_code
See GNUNET_TUN_DNS_RETURN_CODE_ defines.
unsigned int authoritative_answer
Set to 1 if this is an authoritative answer.
Handle to a DNS intercepted reslution request.
struct GNUNET_DNSPARSER_Packet * packet
the dns parser packet received
struct GNUNET_DNS_RequestHandle * request_handle
the request handle to reply to

References _, GNUNET_TIME_Absolute::abs_value_us, GNUNET_DNSPARSER_Packet::additional_records, GNUNET_DNSPARSER_Packet::answers, GNUNET_TUN_DnsFlags::authoritative_answer, data, GNUNET_DNSPARSER_RawRecord::data, GNUNET_DNSPARSER_Record::data, GNUNET_DNSPARSER_RawRecord::data_len, data_size, GNUNET_GNSRECORD_Data::data_size, GNUNET_DNSPARSER_Record::dns_traffic_class, GNUNET_DNSPARSER_Record::expiration_time, GNUNET_GNSRECORD_Data::expiration_time, GNUNET_DNSPARSER_Packet::flags, GNUNET_break, GNUNET_break_op, GNUNET_CONTAINER_DLL_remove, GNUNET_DNS_request_answer(), GNUNET_DNSPARSER_free_packet(), GNUNET_DNSPARSER_pack(), GNUNET_DNSPARSER_parse_mx(), GNUNET_DNSPARSER_parse_name(), GNUNET_DNSPARSER_parse_soa(), GNUNET_DNSPARSER_parse_uri(), GNUNET_DNSPARSER_TYPE_CNAME, GNUNET_DNSPARSER_TYPE_MX, GNUNET_DNSPARSER_TYPE_NS, GNUNET_DNSPARSER_TYPE_PTR, GNUNET_DNSPARSER_TYPE_SOA, GNUNET_DNSPARSER_TYPE_SRV, GNUNET_DNSPARSER_TYPE_URI, GNUNET_ERROR_TYPE_WARNING, GNUNET_free, GNUNET_GNSRECORD_RF_RELATIVE_EXPIRATION, GNUNET_log, GNUNET_NO, GNUNET_OK, GNUNET_TUN_DNS_CLASS_INTERNET, GNUNET_TUN_DNS_RETURN_CODE_NAME_ERROR, GNUNET_TUN_DNS_RETURN_CODE_NO_ERROR, GNUNET_DNSPARSER_Record::hostname, ilh_head, ilh_tail, GNUNET_DNSPARSER_Record::mx, GNUNET_DNSPARSER_Query::name, GNUNET_DNSPARSER_Record::name, GNUNET_DNSPARSER_Packet::num_additional_records, GNUNET_DNSPARSER_Packet::num_answers, InterceptLookupHandle::packet, GNUNET_DNSPARSER_Packet::queries, GNUNET_TUN_DnsFlags::query_or_response, GNUNET_DNSPARSER_Record::raw, rd, rd_count, GNUNET_GNSRECORD_Data::record_type, InterceptLookupHandle::request_handle, ret, GNUNET_TUN_DnsFlags::return_code, GNUNET_DNSPARSER_Record::soa, GNUNET_DNSPARSER_Query::type, GNUNET_DNSPARSER_Record::type, and GNUNET_DNSPARSER_Record::uri.

Referenced by handle_dns_request().

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◆ handle_dns_request()

static void handle_dns_request ( void *  cls,
struct GNUNET_DNS_RequestHandle rh,
size_t  request_length,
const char *  request 
)
static

The DNS request handler.

Called for every incoming DNS request.

Parameters
clsclosure, unused
rhrequest handle to user for reply
request_lengthnumber of bytes in request
requestUDP payload of the DNS request

Definition at line 327 of file gnunet-service-gns_interceptor.c.

331 {
332  struct GNUNET_DNSPARSER_Packet *p;
333  struct InterceptLookupHandle *ilh;
335 
337  "Hijacked a DNS request. Processing.\n");
338  if (NULL == (p = GNUNET_DNSPARSER_parse (request, request_length)))
339  {
341  "Received malformed DNS packet, leaving it untouched.\n");
343  return;
344  }
345 
346  /* Check TLD and decide if we or legacy dns is responsible */
347  if (1 != p->num_queries)
348  {
350  "Not exactly one query in DNS packet. Forwarding untouched.\n");
353  return;
354  }
355 
356  /* Check for GNS TLDs. */
357  if (GNUNET_YES ==
358  GNS_find_tld (GNS_get_tld (p->queries[0].name),
359  &zone))
360  {
361  /* Start resolution in GNS */
362  ilh = GNUNET_new (struct InterceptLookupHandle);
364  ilh_tail,
365  ilh);
366  ilh->packet = p;
367  ilh->request_handle = rh;
369  p->queries[0].type,
370  p->queries[0].name,
373  &reply_to_dns, ilh);
374  return;
375  }
376  /* This request does not concern us. Forward to real DNS. */
378  "Request for `%s' is forwarded to DNS untouched.\n",
379  p->queries[0].name);
382 }
static char * zone
Name of the zone being managed.
int GNS_find_tld(const char *tld_str, struct GNUNET_CRYPTO_PublicKey *pkey)
Find GNS zone belonging to TLD tld.
const char * GNS_get_tld(const char *name)
Obtain the TLD of the given name.
static void reply_to_dns(void *cls, uint32_t rd_count, const struct GNUNET_GNSRECORD_Data *rd)
Reply to dns request with the result from our lookup.
#define MAX_RECURSION
How deep do we allow recursions to go before we abort?
struct GNS_ResolverHandle * GNS_resolver_lookup(const struct GNUNET_CRYPTO_PublicKey *zone, uint32_t record_type, const char *name, enum GNUNET_GNS_LocalOptions options, uint16_t recursion_depth_limit, GNS_ResultProcessor proc, void *proc_cls)
Lookup of a record in a specific zone calls lookup result processor on result.
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
#define GNUNET_CONTAINER_DLL_insert(head, tail, element)
Insert an element at the head of a DLL.
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:725
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
@ GNUNET_GNS_LO_DEFAULT
Defaults, look in cache, then in DHT.
@ GNUNET_YES
@ GNUNET_ERROR_TYPE_DEBUG
#define GNUNET_new(type)
Allocate a struct or union of the given type.
An identity key as per LSD0001.
struct GNS_ResolverHandle * lookup
Handle for the lookup operation.

References GNS_find_tld(), GNS_get_tld(), GNS_resolver_lookup(), GNUNET_CONTAINER_DLL_insert, GNUNET_DNS_request_forward(), GNUNET_DNSPARSER_free_packet(), GNUNET_DNSPARSER_parse(), GNUNET_ERROR_TYPE_DEBUG, GNUNET_ERROR_TYPE_WARNING, GNUNET_GNS_LO_DEFAULT, GNUNET_log, GNUNET_new, GNUNET_YES, ilh_head, ilh_tail, InterceptLookupHandle::lookup, MAX_RECURSION, p, InterceptLookupHandle::packet, reply_to_dns(), request, InterceptLookupHandle::request_handle, and zone.

Referenced by GNS_interceptor_init().

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◆ GNS_interceptor_init()

int GNS_interceptor_init ( const struct GNUNET_CONFIGURATION_Handle c)

Initialize DNS interceptor.

Parameters
cthe configuration
Returns
GNUNET_YES on success GNUNET_SYSERR on error

Definition at line 386 of file gnunet-service-gns_interceptor.c.

387 {
389  "DNS hijacking enabled. Connecting to DNS service.\n");
393  NULL);
394  if (NULL == dns_handle)
395  {
397  _ ("Failed to connect to the DNS service!\n"));
398  return GNUNET_SYSERR;
399  }
400  return GNUNET_YES;
401 }
static void handle_dns_request(void *cls, struct GNUNET_DNS_RequestHandle *rh, size_t request_length, const char *request)
The DNS request handler.
static struct GNUNET_DNS_Handle * dns_handle
Our handle to the DNS handler library.
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_PRE_RESOLUTION
This client should be called on requests that have not yet been resolved as this client provides a re...
@ GNUNET_SYSERR
@ GNUNET_ERROR_TYPE_ERROR
@ GNUNET_ERROR_TYPE_INFO

References _, dns_handle, GNUNET_DNS_connect(), GNUNET_DNS_FLAG_PRE_RESOLUTION, GNUNET_ERROR_TYPE_ERROR, GNUNET_ERROR_TYPE_INFO, GNUNET_log, GNUNET_SYSERR, GNUNET_YES, and handle_dns_request().

Referenced by run().

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◆ GNS_interceptor_done()

void GNS_interceptor_done ( void  )

Disconnect from interceptor.

Stops the interceptor.

Definition at line 408 of file gnunet-service-gns_interceptor.c.

409 {
410  struct InterceptLookupHandle *ilh;
411 
412  while (NULL != (ilh = ilh_head))
413  {
415  ilh_tail,
416  ilh);
420  GNUNET_free (ilh);
421  }
422  if (NULL != dns_handle)
423  {
425  dns_handle = NULL;
426  }
427 }
void GNS_resolver_lookup_cancel(struct GNS_ResolverHandle *rh)
Cancel active resolution (i.e.
void GNUNET_DNS_disconnect(struct GNUNET_DNS_Handle *dh)
Disconnect from the DNS service.
Definition: dns_api.c:363
void GNUNET_DNS_request_drop(struct GNUNET_DNS_RequestHandle *rh)
If a GNUNET_DNS_RequestHandler calls this function, the request is to be dropped and no response shou...
Definition: dns_api.c:265

References dns_handle, GNS_resolver_lookup_cancel(), GNUNET_CONTAINER_DLL_remove, GNUNET_DNS_disconnect(), GNUNET_DNS_request_drop(), GNUNET_DNSPARSER_free_packet(), GNUNET_free, ilh_head, ilh_tail, InterceptLookupHandle::lookup, InterceptLookupHandle::packet, and InterceptLookupHandle::request_handle.

Referenced by shutdown_task().

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Variable Documentation

◆ dns_handle

struct GNUNET_DNS_Handle* dns_handle
static

Our handle to the DNS handler library.

Definition at line 77 of file gnunet-service-gns_interceptor.c.

Referenced by GNS_interceptor_done(), and GNS_interceptor_init().

◆ ilh_head

struct InterceptLookupHandle* ilh_head
static

Head of the DLL.

Definition at line 82 of file gnunet-service-gns_interceptor.c.

Referenced by GNS_interceptor_done(), handle_dns_request(), and reply_to_dns().

◆ ilh_tail

struct InterceptLookupHandle* ilh_tail
static

Tail of the DLL.

Definition at line 87 of file gnunet-service-gns_interceptor.c.

Referenced by GNS_interceptor_done(), handle_dns_request(), and reply_to_dns().