DNS Stub library

Helper library to send DNS requests to DNS resolver. More...

Collaboration diagram for DNS Stub library:

Typedefs
typedef void(*	GNUNET_DNSSTUB_ResultCallback) (void *cls, const struct GNUNET_TUN_DnsHeader *dns, size_t dns_len)
	Function called with the result of a DNS resolution. More...

Functions
struct GNUNET_DNSSTUB_Context *	GNUNET_DNSSTUB_start (unsigned int num_sockets)
	Start a DNS stub resolver. More...
int	GNUNET_DNSSTUB_add_dns_ip (struct GNUNET_DNSSTUB_Context *ctx, const char *dns_ip)
	Add nameserver for use by the DNSSTUB. More...
int	GNUNET_DNSSTUB_add_dns_sa (struct GNUNET_DNSSTUB_Context *ctx, const struct sockaddr *sa)
	Add nameserver for use by the DNSSTUB. More...
void	GNUNET_DNSSTUB_set_retry (struct GNUNET_DNSSTUB_Context *ctx, struct GNUNET_TIME_Relative retry_freq)
	How long should we try requests before timing out? Only effective for requests issued after this call. More...
void	GNUNET_DNSSTUB_stop (struct GNUNET_DNSSTUB_Context *ctx)
	Cleanup DNSSTUB resolver. More...
struct GNUNET_DNSSTUB_RequestSocket *	GNUNET_DNSSTUB_resolve (struct GNUNET_DNSSTUB_Context *ctx, const void *request, size_t request_len, GNUNET_DNSSTUB_ResultCallback rc, void *rc_cls)
	Perform DNS resolution using our default IP from init. More...
void	GNUNET_DNSSTUB_resolve_cancel (struct GNUNET_DNSSTUB_RequestSocket *rs)
	Cancel DNS resolution. More...

Detailed Description

Helper library to send DNS requests to DNS resolver.

Typedef Documentation

GNUNET_DNSSTUB_ResultCallback

typedef void(* GNUNET_DNSSTUB_ResultCallback) (void *cls, const struct GNUNET_TUN_DnsHeader *dns, size_t dns_len)

Function called with the result of a DNS resolution.

Once this function is called, the resolution request is automatically cancelled / cleaned up. In particular, the function will only be called once.

Parameters

cls	closure
dns	dns response, NULL on hard error (i.e. timeout)
dns_len	number of bytes in dns

Definition at line 122 of file gnunet_dnsstub_lib.h.

Function Documentation

GNUNET_DNSSTUB_start()

struct GNUNET_DNSSTUB_Context* GNUNET_DNSSTUB_start

(

unsigned int

num_sockets

)

Start a DNS stub resolver.

Parameters

num_sockets

how many sockets should we open in parallel for DNS queries for this stub?

Returns

NULL on error

Definition at line 586 of file dnsstub.c.

{
  struct GNUNET_DNSSTUB_Context *ctx;
 
  if (0 == num_sockets)
  {
    GNUNET_break (0);
    return NULL;
  }
  ctx = GNUNET_new (struct GNUNET_DNSSTUB_Context);
  ctx->num_sockets = num_sockets;
  ctx->sockets =
    GNUNET_new_array (num_sockets, struct GNUNET_DNSSTUB_RequestSocket);
  ctx->retry_freq = DNS_RETRANSMIT_DELAY;
  return ctx;
}

References ctx, DNS_RETRANSMIT_DELAY, GNUNET_break, GNUNET_new, GNUNET_new_array, GNUNET_DNSSTUB_Context::num_sockets, GNUNET_DNSSTUB_Context::retry_freq, and GNUNET_DNSSTUB_Context::sockets.

Referenced by advertise_dns_exit(), init_cb(), main(), recursive_gns2dns_resolution(), and run().

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GNUNET_DNSSTUB_add_dns_ip()

int GNUNET_DNSSTUB_add_dns_ip	(	struct GNUNET_DNSSTUB_Context *	ctx,
		const char *	dns_ip
	)

Add nameserver for use by the DNSSTUB.

We will use all provided nameservers for resolution (round-robin).

Parameters

ctx	resolver context to modify
dns_ip	target IP address to use (as string)

Returns

GNUNET_OK on success

Definition at line 613 of file dnsstub.c.

{
  struct DnsServer *ds;
  struct in_addr i4;
  struct in6_addr i6;
 
  ds = GNUNET_new (struct DnsServer);
  if (1 == inet_pton (AF_INET, dns_ip, &i4))
  {
    struct sockaddr_in *s4 = (struct sockaddr_in *) &ds->ss;
 
    s4->sin_family = AF_INET;
    s4->sin_port = htons (53);
    s4->sin_addr = i4;
#if HAVE_SOCKADDR_IN_SIN_LEN
    s4->sin_len = (u_char) sizeof(struct sockaddr_in);
#endif
  }
  else if (1 == inet_pton (AF_INET6, dns_ip, &i6))
  {
    struct sockaddr_in6 *s6 = (struct sockaddr_in6 *) &ds->ss;
 
    s6->sin6_family = AF_INET6;
    s6->sin6_port = htons (53);
    s6->sin6_addr = i6;
#if HAVE_SOCKADDR_IN_SIN_LEN
    s6->sin6_len = (u_char) sizeof(struct sockaddr_in6);
#endif
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Malformed IP address `%s' for DNS server\n",
                dns_ip);
    GNUNET_free (ds);
    return GNUNET_SYSERR;
  }
  GNUNET_CONTAINER_DLL_insert (ctx->dns_head, ctx->dns_tail, ds);
  return GNUNET_OK;
}

References ctx, GNUNET_DNSSTUB_Context::dns_head, dns_ip, GNUNET_DNSSTUB_Context::dns_tail, ds, GNUNET_CONTAINER_DLL_insert, GNUNET_ERROR_TYPE_DEBUG, GNUNET_free, GNUNET_log, GNUNET_new, GNUNET_OK, and GNUNET_SYSERR.

Referenced by advertise_dns_exit(), init_cb(), main(), recursive_gns2dns_resolution(), and run().

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GNUNET_DNSSTUB_add_dns_sa()

int GNUNET_DNSSTUB_add_dns_sa	(	struct GNUNET_DNSSTUB_Context *	ctx,
		const struct sockaddr *	sa
	)

Add nameserver for use by the DNSSTUB.

We will use all provided nameservers for resolution (round-robin).

Parameters

ctx	resolver context to modify
sa	socket address of DNS resolver to use

Returns

GNUNET_OK on success

Definition at line 665 of file dnsstub.c.

{
  struct DnsServer *ds;
 
  ds = GNUNET_new (struct DnsServer);
  switch (sa->sa_family)
  {
  case AF_INET :
    GNUNET_memcpy (&ds->ss, sa, sizeof(struct sockaddr_in));
    break;
 
  case AF_INET6:
    GNUNET_memcpy (&ds->ss, sa, sizeof(struct sockaddr_in6));
    break;
 
  default:
    GNUNET_break (0);
    GNUNET_free (ds);
    return GNUNET_SYSERR;
  }
  GNUNET_CONTAINER_DLL_insert (ctx->dns_head, ctx->dns_tail, ds);
  return GNUNET_OK;
}

References ctx, GNUNET_DNSSTUB_Context::dns_head, GNUNET_DNSSTUB_Context::dns_tail, ds, GNUNET_break, GNUNET_CONTAINER_DLL_insert, GNUNET_free, GNUNET_memcpy, GNUNET_new, GNUNET_OK, and GNUNET_SYSERR.

Referenced by handle_gns2dns_ip(), and handle_gns2dns_result().

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GNUNET_DNSSTUB_set_retry()

void GNUNET_DNSSTUB_set_retry	(	struct GNUNET_DNSSTUB_Context *	ctx,
		struct GNUNET_TIME_Relative	retry_freq
	)

How long should we try requests before timing out? Only effective for requests issued after this call.

Parameters

ctx	resolver context to modify
retry_freq	how long to wait between retries

Definition at line 692 of file dnsstub.c.

{
  ctx->retry_freq = retry_freq;
}

References ctx, and GNUNET_DNSSTUB_Context::retry_freq.

GNUNET_DNSSTUB_stop()

void GNUNET_DNSSTUB_stop

(

struct GNUNET_DNSSTUB_Context *

ctx

)

Cleanup DNSSTUB resolver.

Parameters

ctx	stub resolver to clean up

Definition at line 705 of file dnsstub.c.

{
  struct DnsServer *ds;
 
  while (NULL != (ds = ctx->dns_head))
  {
    GNUNET_CONTAINER_DLL_remove (ctx->dns_head, ctx->dns_tail, ds);
    GNUNET_free (ds);
  }
  for (unsigned int i = 0; i < ctx->num_sockets; i++)
    cleanup_rs (&ctx->sockets[i]);
  GNUNET_free (ctx->sockets);
  GNUNET_free (ctx);
}

References cleanup_rs(), ctx, GNUNET_DNSSTUB_Context::dns_head, GNUNET_DNSSTUB_Context::dns_tail, ds, GNUNET_CONTAINER_DLL_remove, GNUNET_free, GNUNET_DNSSTUB_Context::num_sockets, and GNUNET_DNSSTUB_Context::sockets.

Referenced by cleanup(), cleanup_task(), do_shutdown(), GNS_resolver_lookup_cancel(), run(), and shutdown_task().

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GNUNET_DNSSTUB_resolve()

struct GNUNET_DNSSTUB_RequestSocket* GNUNET_DNSSTUB_resolve	(	struct GNUNET_DNSSTUB_Context *	ctx,
		const void *	request,
		size_t	request_len,
		GNUNET_DNSSTUB_ResultCallback	rc,
		void *	rc_cls
	)

Perform DNS resolution using our default IP from init.

Parameters

ctx	stub resolver to use
request	DNS request to transmit
request_len	number of bytes in msg
rc	function to call with result (once)
rc_cls	closure for rc

Returns

socket used for the request, NULL on error

Parameters

ctx	stub resolver to use
request	DNS request to transmit
request_len	number of bytes in msg
rc	function to call with result
rc_cls	closure for 'rc'

Returns

socket used for the request, NULL on error

Definition at line 526 of file dnsstub.c.

{
  struct GNUNET_DNSSTUB_RequestSocket *rs;
 
  if (NULL == ctx->dns_head)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "No DNS server configured for resolution\n");
    return NULL;
  }
  if (NULL == (rs = get_request_socket (ctx)))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "No request socket available for DNS resolution\n");
    return NULL;
  }
  rs->ds_pos = ctx->dns_head;
  rs->rc = rc;
  rs->rc_cls = rc_cls;
  rs->request = GNUNET_memdup (request, request_len);
  rs->request_len = request_len;
  rs->retry_task = GNUNET_SCHEDULER_add_now (&transmit_query, rs);
  return rs;
}

References ctx, GNUNET_DNSSTUB_Context::dns_head, GNUNET_DNSSTUB_RequestSocket::ds_pos, get_request_socket(), GNUNET_ERROR_TYPE_ERROR, GNUNET_log, GNUNET_memdup, GNUNET_SCHEDULER_add_now(), GNUNET_DNSSTUB_RequestSocket::rc, GNUNET_DNSSTUB_RequestSocket::rc_cls, GNUNET_DNSSTUB_RequestSocket::request, request, GNUNET_DNSSTUB_RequestSocket::request_len, GNUNET_DNSSTUB_RequestSocket::retry_task, and transmit_query().

Referenced by handle_dns_request(), handle_resolve_result(), next_phase(), process_queue(), recursive_dns_resolution(), resolve_and_cache(), result_processor(), and submit_req().

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GNUNET_DNSSTUB_resolve_cancel()

void GNUNET_DNSSTUB_resolve_cancel

(

struct GNUNET_DNSSTUB_RequestSocket *

rs

)

Cancel DNS resolution.

Parameters

rs	resolution to cancel

Definition at line 562 of file dnsstub.c.

{
  rs->rc = NULL;
  if (NULL != rs->retry_task)
  {
    GNUNET_SCHEDULER_cancel (rs->retry_task);
    rs->retry_task = NULL;
  }
  if (NULL != rs->read_task)
  {
    GNUNET_SCHEDULER_cancel (rs->read_task);
    rs->read_task = NULL;
  }
}

References GNUNET_SCHEDULER_cancel(), GNUNET_DNSSTUB_RequestSocket::rc, GNUNET_DNSSTUB_RequestSocket::read_task, and GNUNET_DNSSTUB_RequestSocket::retry_task.

Referenced by dns_result_parser(), dns_result_processor(), do_timeout(), free_active_lookup(), GNS_resolver_lookup_cancel(), handle_resolve_result(), and process_result().

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