dns_api.c File Reference

API to access the DNS service. More...

#include "platform.h"
#include "gnunet_dns_service.h"
#include "dns.h"

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Data Structures
struct	GNUNET_DNS_RequestHandle
	Handle to identify an individual DNS request. More...
struct	GNUNET_DNS_Handle
	DNS handle. More...

Functions
static void	reconnect (void *cls)
	Reconnect to the DNS service.
static void	force_reconnect (struct GNUNET_DNS_Handle *dh)
	Drop the existing connection and reconnect to the DNS service.
static void	mq_error_handler (void *cls, enum GNUNET_MQ_Error error)
	Generic error handler, called with the appropriate error code and the same closure specified at the creation of the message queue.
static int	check_request (void *cls, const struct GNUNET_DNS_Request *req)
	This receives packets from the DNS service and calls the application to check that the request is well-formed.
static void	handle_request (void *cls, const struct GNUNET_DNS_Request *req)
	This receives packets from the DNS service and calls the application to handle it.
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 global DNS for resolution.
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.
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).
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.
void	GNUNET_DNS_disconnect (struct GNUNET_DNS_Handle *dh)
	Disconnect from the DNS service.

Detailed Description

API to access the DNS service.

Author

Christian Grothoff

Definition in file dns_api.c.

Function Documentation

reconnect()

static void reconnect ( void *  cls )

static

Reconnect to the DNS service.

Parameters

cls	handle with the connection to connect

Definition at line 196 of file dns_api.c.

{
  struct GNUNET_DNS_Handle *dh = cls;
  struct GNUNET_MQ_MessageHandler handlers[] = {
    GNUNET_MQ_hd_var_size (request,
                           GNUNET_MESSAGE_TYPE_DNS_CLIENT_REQUEST,
                           struct GNUNET_DNS_Request,
                           dh),
    GNUNET_MQ_handler_end ()
  };
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_DNS_Register *msg;
 
  dh->reconnect_task = NULL;
  dh->mq = GNUNET_CLIENT_connect (dh->cfg,
                                  "dns",
                                  handlers,
                                  &mq_error_handler,
                                  dh);
  if (NULL == dh->mq)
    return;
  dh->generation++;
  env = GNUNET_MQ_msg (msg,
                       GNUNET_MESSAGE_TYPE_DNS_CLIENT_INIT);
  msg->flags = htonl (dh->flags);
  GNUNET_MQ_send (dh->mq,
                  env);
}

References GNUNET_DNS_Handle::cfg, env, GNUNET_DNS_Handle::flags, GNUNET_DNS_Handle::generation, GNUNET_CLIENT_connect(), GNUNET_MESSAGE_TYPE_DNS_CLIENT_INIT, GNUNET_MESSAGE_TYPE_DNS_CLIENT_REQUEST, GNUNET_MQ_handler_end, GNUNET_MQ_hd_var_size, GNUNET_MQ_msg, GNUNET_MQ_send(), handlers, GNUNET_DNS_Handle::mq, mq_error_handler(), msg, GNUNET_DNS_Handle::reconnect_task, and request.

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force_reconnect()

static void force_reconnect ( struct GNUNET_DNS_Handle *  dh )

static

Drop the existing connection and reconnect to the DNS service.

Parameters

dh	handle with the connection

Definition at line 116 of file dns_api.c.

{
  if (NULL != dh->mq)
  {
    GNUNET_MQ_destroy (dh->mq);
    dh->mq = NULL;
  }
  dh->reconnect_task =
    GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
                                  &reconnect,
                                  dh);
}

References GNUNET_MQ_destroy(), GNUNET_SCHEDULER_add_delayed(), GNUNET_TIME_UNIT_SECONDS, GNUNET_DNS_Handle::mq, reconnect(), and GNUNET_DNS_Handle::reconnect_task.

Referenced by mq_error_handler().

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mq_error_handler()

static void mq_error_handler ( void *  cls, enum GNUNET_MQ_Error  error  )

static

Generic error handler, called with the appropriate error code and the same closure specified at the creation of the message queue.

Not every message queue implementation supports an error handler.

Parameters

cls	closure with the struct GNUNET_DNS_Handle *
error	error code

Definition at line 139 of file dns_api.c.

{
  struct GNUNET_DNS_Handle *dh = cls;
 
  force_reconnect (dh);
}

References force_reconnect().

Referenced by reconnect().

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check_request()

static int check_request ( void *  cls, const struct GNUNET_DNS_Request *  req  )

static

This receives packets from the DNS service and calls the application to check that the request is well-formed.

Parameters

cls	the struct GNUNET_DNS_Handle
req	message from the service (request)

Definition at line 156 of file dns_api.c.

{
  if (0 != ntohl (req->reserved))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}

References GNUNET_break, GNUNET_OK, GNUNET_SYSERR, and GNUNET_DNS_Request::reserved.

handle_request()

static void handle_request ( void *  cls, const struct GNUNET_DNS_Request *  req  )

static

This receives packets from the DNS service and calls the application to handle it.

Parameters

cls	the struct GNUNET_DNS_Handle *
req	message from the service (request)

Definition at line 176 of file dns_api.c.

{
  struct GNUNET_DNS_Handle *dh = cls;
  size_t payload_length = ntohs (req->header.size) - sizeof(*req);
  struct GNUNET_DNS_RequestHandle *rh;
 
  rh = GNUNET_new (struct GNUNET_DNS_RequestHandle);
  rh->dh = dh;
  rh->request_id = req->request_id;
  rh->generation = dh->generation;
  dh->pending_requests++;
  dh->rh (dh->rh_cls,
          rh,
          payload_length,
          (const char *) &req[1]);
}

References GNUNET_DNS_RequestHandle::dh, GNUNET_DNS_RequestHandle::generation, GNUNET_DNS_Handle::generation, GNUNET_new, GNUNET_DNS_Request::header, GNUNET_DNS_Handle::pending_requests, GNUNET_DNS_Request::request_id, GNUNET_DNS_RequestHandle::request_id, GNUNET_DNS_Handle::rh, GNUNET_DNS_Handle::rh_cls, and GNUNET_MessageHeader::size.