DNS service

Collaboration diagram for DNS service:

Typedefs
typedef void(*	GNUNET_DNS_RequestHandler) (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 do something with it. More...

Enumerations
enum	GNUNET_DNS_Flags {   GNUNET_DNS_FLAG_NEVER = 0 , GNUNET_DNS_FLAG_REQUEST_MONITOR = 1 , GNUNET_DNS_FLAG_PRE_RESOLUTION = 2 , GNUNET_DNS_FLAG_POST_RESOLUTION = 4 ,   GNUNET_DNS_FLAG_RESPONSE_MONITOR = 8 }
	Flags that specify when to call the client's handler. More...

Functions
void	GNUNET_DNS_request_forward (struct GNUNET_DNS_RequestHandle *rh)
	If a GNUNET_DNS_RequestHandler calls this function, the client has no desire to interfere with the request and it should continue to be processed normally. More...
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 should be generated. More...
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 data provided to this call (with the modifications the function might have made). More...
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. More...
void	GNUNET_DNS_disconnect (struct GNUNET_DNS_Handle *dh)
	Disconnect from the DNS service. More...

Detailed Description

See also

Documentation

Typedef Documentation

GNUNET_DNS_RequestHandler

typedef void(* GNUNET_DNS_RequestHandler) (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 do something with it.

The function has then the chance to generate or modify the response by calling one of the three "GNUNET_DNS_request_*" continuations.

When a request is intercepted, this function is called first to give the client a chance to do the complete address resolution; "rdata" will be NULL for this first call for a DNS request, unless some other client has already filled in a response.

If multiple clients exist, all of them are called before the global DNS. The global DNS is only called if all of the clients' functions call GNUNET_DNS_request_forward. Functions that call GNUNET_DNS_request_forward will be called again before a final response is returned to the application. If any of the clients' functions call GNUNET_DNS_request_drop, the response is dropped.

Parameters

cls	closure
rh	request handle to user for reply
request_length	number of bytes in request
request	udp payload of the DNS request

Definition at line 126 of file gnunet_dns_service.h.

Enumeration Type Documentation

GNUNET_DNS_Flags

enum GNUNET_DNS_Flags

Flags that specify when to call the client's handler.

Enumerator
GNUNET_DNS_FLAG_NEVER	Useless option: never call the client.
GNUNET_DNS_FLAG_REQUEST_MONITOR	Set this flag to see all requests first prior to resolution (for monitoring). Clients that set this flag must then call "GNUNET_DNS_request_forward" when they process a request for the first time. Calling "GNUNET_DNS_request_answer" is not allowed for MONITOR peers.
GNUNET_DNS_FLAG_PRE_RESOLUTION	This client should be called on requests that have not yet been resolved as this client provides a resolution service. Note that this does not guarantee that the client will see all requests as another client might be called first and that client might have already done the resolution, in which case other pre-resolution clients won't see the request anymore.
GNUNET_DNS_FLAG_POST_RESOLUTION	This client wants to be called on the results of a DNS resolution (either resolved by PRE-RESOLUTION clients or the global DNS). The client then has a chance to modify the answer (or cause it to be dropped). There is no guarantee that other POST-RESOLUTION client's won't modify (or drop) the answer afterwards.
GNUNET_DNS_FLAG_RESPONSE_MONITOR	Set this flag to see all requests just before they are returned to the network. Clients that set this flag must then call "GNUNET_DNS_request_forward" when they process a request for the last time. Calling "GNUNET_DNS_request_answer" is not allowed for MONITOR peers.

Definition at line 56 of file gnunet_dns_service.h.

{
  GNUNET_DNS_FLAG_NEVER = 0,
 
  GNUNET_DNS_FLAG_REQUEST_MONITOR = 1,
 
  GNUNET_DNS_FLAG_PRE_RESOLUTION = 2,
 
  GNUNET_DNS_FLAG_POST_RESOLUTION = 4,
 
  GNUNET_DNS_FLAG_RESPONSE_MONITOR = 8
};

Function Documentation

GNUNET_DNS_request_forward()

void GNUNET_DNS_request_forward

(

struct GNUNET_DNS_RequestHandle *

rh

)

If a GNUNET_DNS_RequestHandler calls this function, the client has no desire to interfere with the request and it should continue to be processed normally.

Parameters

rh	request that should now be forwarded

If a GNUNET_DNS_RequestHandler calls this function, the client has no desire to interfere with the request and it should continue to be processed normally.

Once a global response has been obtained, the request handler is AGAIN called to give it a chance to observe and modify the response after the "normal" resolution. It is not legal for the request handler to call this function if a response is already present.

Parameters

rh	request that should now be forwarded

Definition at line 237 of file dns_api.c.

{
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_DNS_Response *resp;
 
  GNUNET_assert (0 < rh->dh->pending_requests--);
  if (rh->generation != rh->dh->generation)
  {
    GNUNET_free (rh);
    return;
  }
  env = GNUNET_MQ_msg (resp,
                       GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE);
  resp->drop_flag = htonl (1);
  resp->request_id = rh->request_id;
  GNUNET_MQ_send (rh->dh->mq,
                  env);
  GNUNET_free (rh);
}

References GNUNET_DNS_RequestHandle::dh, GNUNET_DNS_Response::drop_flag, env, GNUNET_DNS_RequestHandle::generation, GNUNET_DNS_Handle::generation, GNUNET_assert, GNUNET_free, GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE, GNUNET_MQ_msg, GNUNET_MQ_send(), GNUNET_DNS_Handle::mq, GNUNET_DNS_Handle::pending_requests, GNUNET_DNS_Response::request_id, and GNUNET_DNS_RequestHandle::request_id.

Referenced by display_request(), dns_post_request_handler(), handle_dns_request(), and modify_request().

Here is the call graph for this function:

Here is the caller graph for this function:

GNUNET_DNS_request_drop()

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 should be generated.

Parameters

rh	request that should now be dropped

Definition at line 265 of file dns_api.c.

{
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_DNS_Response *resp;
 
  GNUNET_assert (0 < rh->dh->pending_requests--);
  if (rh->generation != rh->dh->generation)
  {
    GNUNET_free (rh);
    return;
  }
  env = GNUNET_MQ_msg (resp,
                       GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE);
  resp->request_id = rh->request_id;
  resp->drop_flag = htonl (0);
  GNUNET_MQ_send (rh->dh->mq,
                  env);
  GNUNET_free (rh);
}

References GNUNET_DNS_RequestHandle::dh, GNUNET_DNS_Response::drop_flag, env, GNUNET_DNS_RequestHandle::generation, GNUNET_DNS_Handle::generation, GNUNET_assert, GNUNET_free, GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE, GNUNET_MQ_msg, GNUNET_MQ_send(), GNUNET_DNS_Handle::mq, GNUNET_DNS_Handle::pending_requests, GNUNET_DNS_Response::request_id, and GNUNET_DNS_RequestHandle::request_id.

Referenced by abort_all_requests(), dns_post_request_handler(), dns_pre_request_handler(), finish_request(), GNS_interceptor_done(), timeout_request(), and vpn_allocation_callback().

Here is the call graph for this function:

Here is the caller graph for this function:

GNUNET_DNS_request_answer()

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 data provided to this call (with the modifications the function might have made).

The reply given must always be a valid DNS reply and not a mutated DNS request.

Parameters

rh	request that should now be answered
reply_length	size of reply (uint16_t to force sane size)
reply	reply data
rh	request that should now be answered
reply_length	size of reply (uint16_t to force sane size)
reply	reply data

Definition at line 296 of file dns_api.c.

{
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_DNS_Response *resp;
 
  GNUNET_assert (0 < rh->dh->pending_requests--);
  if (rh->generation != rh->dh->generation)
  {
    GNUNET_free (rh);
    return;
  }
  if (reply_length + sizeof(struct GNUNET_DNS_Response)
      >= GNUNET_MAX_MESSAGE_SIZE)
  {
    GNUNET_break (0);
    GNUNET_free (rh);
    return;
  }
  env = GNUNET_MQ_msg_extra (resp,
                             reply_length,
                             GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE);
  resp->drop_flag = htonl (2);
  resp->request_id = rh->request_id;
  GNUNET_memcpy (&resp[1],
                 reply,
                 reply_length);
  GNUNET_MQ_send (rh->dh->mq,
                  env);
  GNUNET_free (rh);
}

References GNUNET_DNS_RequestHandle::dh, GNUNET_DNS_Response::drop_flag, env, GNUNET_DNS_RequestHandle::generation, GNUNET_DNS_Handle::generation, GNUNET_assert, GNUNET_break, GNUNET_free, GNUNET_MAX_MESSAGE_SIZE, GNUNET_memcpy, GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE, GNUNET_MQ_msg_extra, GNUNET_MQ_send(), GNUNET_DNS_Handle::mq, GNUNET_DNS_Handle::pending_requests, GNUNET_DNS_Response::request_id, and GNUNET_DNS_RequestHandle::request_id.

Referenced by finish_request(), handle_dns_response(), modify_request(), and reply_to_dns().

Here is the call graph for this function:

Here is the caller graph for this function:

GNUNET_DNS_connect()

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.

Parameters

cfg	configuration to use
flags	when to call rh
rh	function to call with DNS requests
rh_cls	closure to pass to rh

Returns

DNS handle

Definition at line 340 of file dns_api.c.

{
  struct GNUNET_DNS_Handle *dh;
 
  dh = GNUNET_new (struct GNUNET_DNS_Handle);
  dh->cfg = cfg;
  dh->flags = flags;
  dh->rh = rh;
  dh->rh_cls = rh_cls;
  dh->reconnect_task = GNUNET_SCHEDULER_add_now (&reconnect, dh);
  return dh;
}

References cfg, GNUNET_DNS_Handle::cfg, GNUNET_DNS_Handle::flags, GNUNET_new, GNUNET_SCHEDULER_add_now(), reconnect(), GNUNET_DNS_Handle::reconnect_task, GNUNET_DNS_Handle::rh, and GNUNET_DNS_Handle::rh_cls.

Referenced by GNS_interceptor_init(), and run().

Here is the call graph for this function:

Here is the caller graph for this function:

GNUNET_DNS_disconnect()

void GNUNET_DNS_disconnect

(

struct GNUNET_DNS_Handle *

dh

)

Disconnect from the DNS service.

Parameters

dh	DNS handle

Definition at line 363 of file dns_api.c.

{
  if (NULL != dh->mq)
  {
    GNUNET_MQ_destroy (dh->mq);
    dh->mq = NULL;
  }
  if (NULL != dh->reconnect_task)
  {
    GNUNET_SCHEDULER_cancel (dh->reconnect_task);
    dh->reconnect_task = NULL;
  }
  /* make sure client has no pending requests left over! */
  GNUNET_break (0 == dh->pending_requests);
  GNUNET_free (dh);
}

References GNUNET_break, GNUNET_free, GNUNET_MQ_destroy(), GNUNET_SCHEDULER_cancel(), GNUNET_DNS_Handle::mq, GNUNET_DNS_Handle::pending_requests, and GNUNET_DNS_Handle::reconnect_task.

Referenced by cleanup(), do_disconnect(), and GNS_interceptor_done().

Here is the call graph for this function:

Here is the caller graph for this function: