GNUnet  0.11.x
Data Structures | Macros | Functions | Variables
gnunet-service-gns_interceptor.c File Reference

GNUnet GNS interceptor logic. More...

#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_dns_service.h"
#include "gnunet_dnsparser_lib.h"
#include "gnunet-service-gns.h"
#include "gnunet-service-gns_resolver.h"
#include "gnunet-service-gns_interceptor.h"
#include "gns.h"
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)
 Initialized the 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 39 of file gnunet-service-gns_interceptor.c.

Referenced by handle_dns_request().

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 99 of file gnunet-service-gns_interceptor.c.

References _, GNUNET_TIME_Absolute::abs_value_us, GNUNET_DNSPARSER_Packet::additional_records, GNUNET_DNSPARSER_Packet::answers, GNUNET_TUN_DnsFlags::authoritative_answer, buf, 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_GNSRECORD_Data::expiration_time, GNUNET_DNSPARSER_Record::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_TYPE_CNAME, GNUNET_DNSPARSER_TYPE_MX, GNUNET_DNSPARSER_TYPE_NS, GNUNET_DNSPARSER_TYPE_PTR, GNUNET_DNSPARSER_TYPE_SOA, GNUNET_DNSPARSER_TYPE_SRV, 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, len, 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, GNUNET_GNSRECORD_Data::record_type, InterceptLookupHandle::request_handle, ret, GNUNET_TUN_DnsFlags::return_code, GNUNET_DNSPARSER_Record::soa, GNUNET_DNSPARSER_Query::type, and GNUNET_DNSPARSER_Record::type.

Referenced by handle_dns_request().

101 {
102  struct InterceptLookupHandle *ilh = cls;
103  struct GNUNET_DNSPARSER_Packet *packet = ilh->packet;
104  struct GNUNET_DNSPARSER_Query *query = &packet->queries[0];
105  uint32_t i;
106  size_t len;
107  int ret;
108  char *buf;
109  unsigned int num_answers;
110  unsigned int skip_answers;
111  unsigned int skip_additional;
112  size_t off = 0;
113 
114  /* Put records in the DNS packet */
115  num_answers = 0;
116  for (i = 0; i < rd_count; i++)
117  if (rd[i].record_type == query->type)
118  num_answers++;
119  skip_answers = 0;
120  skip_additional = 0;
121 
122  {
123  struct GNUNET_DNSPARSER_Record answer_records[num_answers];
124  struct GNUNET_DNSPARSER_Record additional_records[rd_count - num_answers];
125 
126  packet->answers = answer_records;
127  packet->additional_records = additional_records;
128  /* FIXME: need to handle #GNUNET_GNSRECORD_RF_SHADOW_RECORD option
129  (by ignoring records where this flag is set if there is any
130  other record of that type in the result set) */
131  for (i = 0; i < rd_count; i++)
132  {
133  if (rd[i].record_type == query->type)
134  {
135  answer_records[i - skip_answers].name = query->name;
136  answer_records[i - skip_answers].type = rd[i].record_type;
137  switch (rd[i].record_type)
138  {
142  answer_records[i - skip_answers].data.hostname
144  rd[i].data_size,
145  &off);
146  if ((off != rd[i].data_size) ||
147  (NULL == answer_records[i].data.hostname))
148  {
149  GNUNET_break_op (0);
150  skip_answers++;
151  }
152  break;
153 
155  answer_records[i - skip_answers].data.soa
157  rd[i].data_size,
158  &off);
159  if ((off != rd[i].data_size) ||
160  (NULL == answer_records[i].data.soa))
161  {
162  GNUNET_break_op (0);
163  skip_answers++;
164  }
165  break;
166 
168  /* FIXME: SRV is not yet supported */
169  skip_answers++;
170  break;
171 
173  answer_records[i - skip_answers].data.mx
175  rd[i].data_size,
176  &off);
177  if ((off != rd[i].data_size) ||
178  (NULL == answer_records[i].data.hostname))
179  {
180  GNUNET_break_op (0);
181  skip_answers++;
182  }
183  break;
184 
185  default:
186  answer_records[i - skip_answers].data.raw.data_len = rd[i].data_size;
187  answer_records[i - skip_answers].data.raw.data = (char *) rd[i].data;
188  break;
189  }
190  GNUNET_break (0 == (rd[i - skip_answers].flags
192  answer_records[i - skip_answers].expiration_time.abs_value_us =
193  rd[i].expiration_time;
194  answer_records[i - skip_answers].dns_traffic_class =
196  }
197  else
198  {
199  additional_records[i - skip_additional].name = query->name;
200  additional_records[i - skip_additional].type = rd[i].record_type;
201  switch (rd[i].record_type)
202  {
206  additional_records[i - skip_additional].data.hostname
208  rd[i].data_size,
209  &off);
210  if ((off != rd[i].data_size) ||
211  (NULL == additional_records[i].data.hostname))
212  {
213  GNUNET_break_op (0);
214  skip_additional++;
215  }
216  break;
217 
219  additional_records[i - skip_additional].data.soa
221  rd[i].data_size,
222  &off);
223  if ((off != rd[i].data_size) ||
224  (NULL == additional_records[i].data.hostname))
225  {
226  GNUNET_break_op (0);
227  skip_additional++;
228  }
229  break;
230 
232  additional_records[i - skip_additional].data.mx
234  rd[i].data_size,
235  &off);
236  if ((off != rd[i].data_size) ||
237  (NULL == additional_records[i].data.hostname))
238  {
239  GNUNET_break_op (0);
240  skip_additional++;
241  }
242  break;
243 
245  /* FIXME: SRV is not yet supported */
246  skip_answers++;
247  break;
248 
249  default:
250  additional_records[i - skip_additional].data.raw.data_len =
251  rd[i].data_size;
252  additional_records[i - skip_additional].data.raw.data =
253  (char *) rd[i].data;
254  break;
255  }
256  GNUNET_break (0 == (rd[i - skip_additional].flags
258  additional_records[i - skip_additional].expiration_time.abs_value_us =
259  rd[i].expiration_time;
260  additional_records[i - skip_additional].dns_traffic_class =
262  }
263  }
264  packet->num_answers = num_answers - skip_answers;
265  packet->num_additional_records = rd_count - num_answers - skip_additional;
266  packet->flags.authoritative_answer = 1;
267  if (NULL == rd)
269  else
271  packet->flags.query_or_response = 1;
272  ret = GNUNET_DNSPARSER_pack (packet,
273  1024, /* maximum allowed size for DNS reply */
274  &buf,
275  &len);
276  if (GNUNET_OK != ret)
277  {
279  _ ("Error converting GNS response to DNS response!\n"));
280  if (GNUNET_NO == ret)
281  GNUNET_free (buf);
282  }
283  else
284  {
286  len,
287  buf);
288  GNUNET_free (buf);
289  }
290  packet->num_answers = 0;
291  packet->answers = NULL;
292  packet->num_additional_records = 0;
293  packet->additional_records = NULL;
295  }
297  GNUNET_free (ilh);
298 }
#define GNUNET_CONTAINER_DLL_remove(head, tail, element)
Remove an element from a DLL.
struct GNUNET_DNSPARSER_Record * answers
Array of all answers in the packet, must contain "num_answers" entries.
uint16_t type
See GNUNET_DNSPARSER_TYPE_*.
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:334
struct GNUNET_DNSPARSER_Packet * packet
the dns parser packet received
#define GNUNET_DNSPARSER_TYPE_CNAME
static struct InterceptLookupHandle * ilh_tail
Tail of the DLL.
unsigned int return_code
See GNUNET_TUN_DNS_RETURN_CODE_ defines.
static size_t data_size
Number of bytes in data.
Definition: gnunet-abd.c:187
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:1257
Handle to a DNS intercepted reslution request.
static int ret
Return value of the commandline.
Definition: gnunet-abd.c:81
void GNUNET_DNSPARSER_free_packet(struct GNUNET_DNSPARSER_Packet *p)
Free memory taken by a packet.
Definition: dnsparser.c:854
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:391
size_t data_size
Number of bytes in data.
struct GNUNET_DNSPARSER_Record * additional_records
Array of all additional answers in the packet, must contain "num_additional_records" entries...
#define GNUNET_DNSPARSER_TYPE_MX
unsigned int num_answers
Number of answers in the packet, should be 0 for queries.
#define GNUNET_break(cond)
Use this for internal assertion violations that are not fatal (can be handled) but should not occur...
unsigned int authoritative_answer
Set to 1 if this is an authoritative answer.
#define _(String)
GNU gettext support macro.
Definition: platform.h:184
#define GNUNET_DNSPARSER_TYPE_PTR
unsigned int query_or_response
query:0, response:1
#define GNUNET_DNSPARSER_TYPE_SOA
char * name
Name of the record that the query is for (0-terminated).
unsigned int num_additional_records
Number of additional records in the packet, should be 0 for queries.
#define GNUNET_break_op(cond)
Use this for assertion violations caused by other peers (i.e.
uint64_t expiration_time
Expiration time for the DNS record.
static struct InterceptLookupHandle * ilh_head
Head of the DLL.
#define GNUNET_TUN_DNS_RETURN_CODE_NO_ERROR
RFC 1035 codes.
static char buf[2048]
A DNS response record.
struct GNUNET_DNSPARSER_Query * queries
Array of all queries in the packet, must contain "num_queries" entries.
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:436
struct GNUNET_DNS_RequestHandle * request_handle
the request handle to reply to
#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&#39;r...
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:302
#define GNUNET_TUN_DNS_RETURN_CODE_NAME_ERROR
uint32_t record_type
Type of the GNS/DNS record.
#define GNUNET_DNSPARSER_TYPE_NS
Easy-to-process, parsed version of a DNS packet.
#define GNUNET_log(kind,...)
char * name
Name of the record that the query is for (0-terminated).
This expiration time of the record is a relative time (not an absolute time).
struct GNUNET_TUN_DnsFlags flags
Bitfield of DNS flags.
#define GNUNET_DNSPARSER_TYPE_SRV
uint32_t data
The data value.
#define GNUNET_free(ptr)
Wrapper around free.
uint16_t len
length of data (which is always a uint32_t, but presumably this can be used to specify that fewer byt...
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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 310 of file gnunet-service-gns_interceptor.c.

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, InterceptLookupHandle::lookup, MAX_RECURSION, GNUNET_DNSPARSER_Query::name, GNUNET_DNSPARSER_Packet::num_queries, p, InterceptLookupHandle::packet, GNUNET_DNSPARSER_Packet::queries, reply_to_dns(), InterceptLookupHandle::request_handle, and GNUNET_DNSPARSER_Query::type.

Referenced by GNS_interceptor_init().

314 {
315  struct GNUNET_DNSPARSER_Packet *p;
316  struct InterceptLookupHandle *ilh;
318 
320  "Hijacked a DNS request. Processing.\n");
321  if (NULL == (p = GNUNET_DNSPARSER_parse (request, request_length)))
322  {
324  "Received malformed DNS packet, leaving it untouched.\n");
327  return;
328  }
329 
330  /* Check TLD and decide if we or legacy dns is responsible */
331  if (1 != p->num_queries)
332  {
334  "Not exactly one query in DNS packet. Forwarding untouched.\n");
337  return;
338  }
339 
340  /* Check for GNS TLDs. */
341  if (GNUNET_YES ==
343  &zone))
344  {
345  /* Start resolution in GNS */
346  ilh = GNUNET_new (struct InterceptLookupHandle);
348  ilh_tail,
349  ilh);
350  ilh->packet = p;
351  ilh->request_handle = rh;
353  p->queries[0].type,
354  p->queries[0].name,
357  &reply_to_dns, ilh);
358  return;
359  }
360  /* This request does not concern us. Forward to real DNS. */
362  "Request for `%s' is forwarded to DNS untouched.\n",
363  p->queries[0].name);
366 }
uint16_t type
See GNUNET_DNSPARSER_TYPE_*.
static struct GNUNET_VPN_RedirectionRequest * request
Opaque redirection request handle.
Definition: gnunet-vpn.c:41
#define GNUNET_CONTAINER_DLL_insert(head, tail, element)
Insert an element at the head of a DLL.
struct GNUNET_DNSPARSER_Packet * packet
the dns parser packet received
static struct InterceptLookupHandle * ilh_tail
Tail of the DLL.
const char * GNS_get_tld(const char *name)
Obtain the TLD of the given name.
Handle to a DNS intercepted reslution request.
void GNUNET_DNSPARSER_free_packet(struct GNUNET_DNSPARSER_Packet *p)
Free memory taken by a packet.
Definition: dnsparser.c:854
#define GNUNET_new(type)
Allocate a struct or union of the given type.
static char * zone
Name of the zone we manage.
struct GNS_ResolverHandle * lookup
Handle for the lookup operation.
static struct GNUNET_OS_Process * p
Helper process we started.
Definition: gnunet-qr.c:59
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:656
static struct InterceptLookupHandle * ilh_head
Head of the DLL.
struct GNUNET_DNSPARSER_Query * queries
Array of all queries in the packet, must contain "num_queries" entries.
struct GNUNET_DNS_RequestHandle * request_handle
the request handle to reply to
An identity key as per LSD0001.
int GNS_find_tld(const char *tld_str, struct GNUNET_IDENTITY_PublicKey *pkey)
Find GNS zone belonging to TLD tld.
void GNUNET_DNS_request_forward(struct GNUNET_DNS_RequestHandle *rh)
If a GNUNET_DNS_RequestHandler calls this function, the request is given to other clients or the glob...
Definition: dns_api.c:243
Easy-to-process, parsed version of a DNS packet.
#define GNUNET_log(kind,...)
char * name
Name of the record that the query is for (0-terminated).
unsigned int num_queries
Number of queries in the packet.
Defaults, look in cache, then in DHT.
struct GNS_ResolverHandle * GNS_resolver_lookup(const struct GNUNET_IDENTITY_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.
#define MAX_RECURSION
How deep do we allow recursions to go before we abort?
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.
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◆ GNS_interceptor_init()

int GNS_interceptor_init ( const struct GNUNET_CONFIGURATION_Handle c)

Initialized the interceptor.

Initialize DNS interceptor.

Parameters
cthe configuration
Returns
GNUNET_OK on success

Definition at line 376 of file gnunet-service-gns_interceptor.c.

References _, 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().

377 {
379  "DNS hijacking enabled. Connecting to DNS service.\n");
383  NULL);
384  if (NULL == dns_handle)
385  {
387  _ ("Failed to connect to the DNS service!\n"));
388  return GNUNET_SYSERR;
389  }
390  return GNUNET_YES;
391 }
#define _(String)
GNU gettext support macro.
Definition: platform.h:184
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:346
#define GNUNET_log(kind,...)
This client should be called on requests that have not yet been resolved as this client provides a re...
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◆ GNS_interceptor_done()

void GNS_interceptor_done ( void  )

Disconnect from interceptor.

Stops the interceptor.

Definition at line 398 of file gnunet-service-gns_interceptor.c.

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

Referenced by shutdown_task().

399 {
400  struct InterceptLookupHandle *ilh;
401 
402  while (NULL != (ilh = ilh_head))
403  {
405  ilh_tail,
406  ilh);
410  GNUNET_free (ilh);
411  }
412  if (NULL != dns_handle)
413  {
415  dns_handle = NULL;
416  }
417 }
#define GNUNET_CONTAINER_DLL_remove(head, tail, element)
Remove an element from a DLL.
void GNS_resolver_lookup_cancel(struct GNS_ResolverHandle *rh)
Cancel active resolution (i.e.
struct GNUNET_DNSPARSER_Packet * packet
the dns parser packet received
static struct InterceptLookupHandle * ilh_tail
Tail of the DLL.
Handle to a DNS intercepted reslution request.
void GNUNET_DNSPARSER_free_packet(struct GNUNET_DNSPARSER_Packet *p)
Free memory taken by a packet.
Definition: dnsparser.c:854
void GNUNET_DNS_disconnect(struct GNUNET_DNS_Handle *dh)
Disconnect from the DNS service.
Definition: dns_api.c:369
struct GNS_ResolverHandle * lookup
Handle for the lookup operation.
static struct InterceptLookupHandle * ilh_head
Head of the DLL.
static struct GNUNET_DNS_Handle * dns_handle
Our handle to the DNS handler library.
struct GNUNET_DNS_RequestHandle * request_handle
the request handle to reply to
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:271
#define GNUNET_free(ptr)
Wrapper around free.
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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 78 of file gnunet-service-gns_interceptor.c.

◆ ilh_head

struct InterceptLookupHandle* ilh_head
static

Head of the DLL.

Definition at line 83 of file gnunet-service-gns_interceptor.c.

◆ ilh_tail

struct InterceptLookupHandle* ilh_tail
static

Tail of the DLL.

Definition at line 88 of file gnunet-service-gns_interceptor.c.