/*
- This file is part of GNUnet.
- (C) 2010 Christian Grothoff
+ This file is part of GNUnet
+ (C) 2012 Christian Grothoff (and other contributing authors)
+
+ GNUnet is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published
+ by the Free Software Foundation; either version 2, or (at your
+ option) any later version.
+
+ GNUnet is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with GNUnet; see the file COPYING. If not, write to the
+ Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA.
+ */
- GNUnet is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published
- by the Free Software Foundation; either version 3, or (at your
- option) any later version.
+/**
+ * @file dns/dns_api.c
+ * @brief API to access the DNS service.
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "gnunet_dns_service.h"
+#include "dns.h"
- GNUnet is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with GNUnet; see the file COPYING. If not, write to the
- Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA.
-*/
+/**
+ * Reply to send to service.
+ */
+struct ReplyQueueEntry
+{
+ /**
+ * Kept in DLL.
+ */
+ struct ReplyQueueEntry *next;
+
+ /**
+ * Kept in DLL.
+ */
+ struct ReplyQueueEntry *prev;
+
+ /**
+ * Message to transmit, allocated at the end of this struct.
+ */
+ const struct GNUNET_MessageHeader *msg;
+
+};
+
/**
- * @file vpn/gnunet-daemon-vpn-dns.c
- * @brief
- * @author Philipp Toelke
+ * Handle to identify an individual DNS request.
*/
-#include <platform.h>
-#include <gnunet_common.h>
-#include <gnunet_client_lib.h>
-#include <gnunet_os_lib.h>
-#include <gnunet_mesh_service.h>
-#include <gnunet_protocols.h>
-#include <gnunet_server_lib.h>
-#include <gnunet_container_lib.h>
-#include <block_dns.h>
+struct GNUNET_DNS_RequestHandle
+{
-#include "gnunet_dns_service.h"
+ /**
+ * Handle to DNS API.
+ */
+ struct GNUNET_DNS_Handle *dh;
+ /**
+ * Stored in network byte order (as for us, it is just a random number).
+ */
+ uint64_t request_id;
+ /**
+ * Re-connect counter, to make sure we did not reconnect in the meantime.
+ */
+ uint32_t generation;
+
+};
+
+
+/**
+ * DNS handle
+ */
struct GNUNET_DNS_Handle
{
- struct query_packet_list *head;
- struct query_packet_list *tail;
+
+ /**
+ * Connection to DNS service, or NULL.
+ */
struct GNUNET_CLIENT_Connection *dns_connection;
- unsigned char restart_hijack;
+ /**
+ * Handle to active transmission request, or NULL.
+ */
struct GNUNET_CLIENT_TransmitHandle *dns_transmit_handle;
+ /**
+ * Configuration to use.
+ */
const struct GNUNET_CONFIGURATION_Handle *cfg;
- GNUNET_SCHEDULER_Task process_answer_cb;
+ /**
+ * Function to call to get replies.
+ */
+ GNUNET_DNS_RequestHandler rh;
- void *process_answer_cb_cls;
-};
+ /**
+ * Closure for 'rh'.
+ */
+ void *rh_cls;
+
+ /**
+ * Head of replies to transmit.
+ */
+ struct ReplyQueueEntry *rq_head;
+ /**
+ * Tail of replies to transmit.
+ */
+ struct ReplyQueueEntry *rq_tail;
-/**
- * Callback called by notify_transmit_ready; sends dns-queries or rehijack-messages
- * to the service-dns
- * {{{
- */
-size_t
-send_query (void *cls GNUNET_UNUSED, size_t size, void *buf)
-{
- struct GNUNET_DNS_Handle *h = cls;
+ /**
+ * Task to reconnect to the service.
+ */
+ GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
- size_t len;
+ /**
+ * Re-connect counter, to make sure we did not reconnect in the meantime.
+ */
+ uint32_t generation;
+
+ /**
+ * Flags for events we care about.
+ */
+ enum GNUNET_DNS_Flags flags;
- h->dns_transmit_handle = NULL;
+ /**
+ * Did we start the receive loop yet?
+ */
+ int in_receive;
- /*
- * Send the rehijack-message
+ /**
+ * Number of GNUNET_DNS_RequestHandles we have outstanding. Must be 0 before
+ * we can be disconnected.
*/
- if (h->restart_hijack == 1)
- {
- h->restart_hijack = 0;
- /*
- * The message is just a header
- */
- GNUNET_assert (sizeof (struct GNUNET_MessageHeader) <= size);
- struct GNUNET_MessageHeader *hdr = buf;
-
- len = sizeof (struct GNUNET_MessageHeader);
- hdr->size = htons (len);
- hdr->type = htons (GNUNET_MESSAGE_TYPE_REHIJACK);
- }
- else if (h->head != NULL)
- {
- struct query_packet_list *query = h->head;
+ unsigned int pending_requests;
+};
+
+
+/**
+ * Add the given reply to our transmission queue and trigger sending if needed.
+ *
+ * @param dh handle with the connection
+ * @param qe reply to queue
+ */
+static void
+queue_reply (struct GNUNET_DNS_Handle *dh,
+ struct ReplyQueueEntry *qe);
- len = ntohs (query->pkt.hdr.size);
- GNUNET_assert (len <= size);
+/**
+ * Reconnect to the DNS service.
+ *
+ * @param cls handle with the connection to connect
+ * @param tc scheduler context (unused)
+ */
+static void
+reconnect (void *cls,
+ const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+ struct GNUNET_DNS_Handle *dh = cls;
+ struct ReplyQueueEntry *qe;
+ struct GNUNET_DNS_Register *msg;
- memcpy (buf, &query->pkt.hdr, len);
+ dh->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
+ dh->dns_connection = GNUNET_CLIENT_connect ("dns", dh->cfg);
+ if (NULL == dh->dns_connection)
+ return;
+ dh->generation++;
+ qe = GNUNET_malloc (sizeof (struct ReplyQueueEntry) +
+ sizeof (struct GNUNET_DNS_Register));
+ msg = (struct GNUNET_DNS_Register*) &qe[1];
+ qe->msg = &msg->header;
+ msg->header.size = htons (sizeof (struct GNUNET_DNS_Register));
+ msg->header.type = htons (GNUNET_MESSAGE_TYPE_DNS_CLIENT_INIT);
+ msg->flags = htonl (dh->flags);
+ queue_reply (dh, qe);
+}
- GNUNET_CONTAINER_DLL_remove (h->head, h->tail, query);
- GNUNET_free (query);
- }
- else
+/**
+ * Disconnect from the DNS service.
+ *
+ * @param dh handle with the connection to disconnect
+ */
+static void
+disconnect (struct GNUNET_DNS_Handle *dh)
+{
+ struct ReplyQueueEntry *qe;
+
+ if (NULL != dh->dns_transmit_handle)
{
- GNUNET_break (0);
- len = 0;
+ GNUNET_CLIENT_notify_transmit_ready_cancel (dh->dns_transmit_handle);
+ dh->dns_transmit_handle = NULL;
}
-
- /*
- * Check whether more data is to be sent
- */
- if (h->head != NULL)
+ if (NULL != dh->dns_connection)
{
- h->dns_transmit_handle =
- GNUNET_CLIENT_notify_transmit_ready (h->dns_connection,
- ntohs (h->head->pkt.hdr.size),
- GNUNET_TIME_UNIT_FOREVER_REL,
- GNUNET_YES, &send_query, h);
+ GNUNET_CLIENT_disconnect (dh->dns_connection);
+ dh->dns_connection = NULL;
}
- else if (h->restart_hijack == 1)
+ while (NULL != (qe = dh->rq_head))
{
- h->dns_transmit_handle =
- GNUNET_CLIENT_notify_transmit_ready (h->dns_connection,
- sizeof (struct
- GNUNET_MessageHeader),
- GNUNET_TIME_UNIT_FOREVER_REL,
- GNUNET_YES, &send_query, h);
+ GNUNET_CONTAINER_DLL_remove (dh->rq_head,
+ dh->rq_tail,
+ qe);
+ GNUNET_free (qe);
}
-
- return len;
+ dh->in_receive = GNUNET_NO;
}
-/* }}} */
-
-
/**
- * This receives packets from the service-dns and schedules process_answer to
- * handle it
+ * This receives packets from the DNS service and calls the application to
+ * handle it.
+ *
+ * @param cls the struct GNUNET_DNS_Handle
+ * @param msg message from the service (request)
*/
static void
-dns_answer_handler (void *cls,
- const struct GNUNET_MessageHeader *msg)
+request_handler (void *cls,
+ const struct GNUNET_MessageHeader *msg)
{
- struct GNUNET_DNS_Handle *h = cls;
+ struct GNUNET_DNS_Handle *dh = cls;
+ const struct GNUNET_DNS_Request *req;
+ struct GNUNET_DNS_RequestHandle *rh;
+ size_t payload_length;
/* the service disconnected, reconnect after short wait */
if (msg == NULL)
{
- if (h->dns_transmit_handle != NULL)
- GNUNET_CLIENT_notify_transmit_ready_cancel (h->dns_transmit_handle);
- h->dns_transmit_handle = NULL;
- GNUNET_CLIENT_disconnect (h->dns_connection, GNUNET_NO);
- h->dns_connection = NULL;
-#if 0
- h->conn_task =
+ disconnect (dh);
+ dh->reconnect_task =
GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
- &connect_to_service_dns, h);
-#endif
+ &reconnect, dh);
return;
}
-
- /* the service did something strange, reconnect immediately */
- if (msg->type != htons (GNUNET_MESSAGE_TYPE_VPN_DNS_LOCAL_RESPONSE_DNS))
+ if ( (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_DNS_CLIENT_REQUEST) ||
+ (ntohs (msg->size) < sizeof (struct GNUNET_DNS_Request)) )
{
+ /* the service did something strange, reconnect immediately */
GNUNET_break (0);
- GNUNET_CLIENT_disconnect (h->dns_connection, GNUNET_NO);
- h->dns_connection = NULL;
-#if 0
- conn_task = GNUNET_SCHEDULER_add_now (&connect_to_service_dns, NULL);
-#endif
+ disconnect (dh);
+ dh->reconnect_task = GNUNET_SCHEDULER_add_now (&reconnect, dh);
return;
}
- void *pkt = GNUNET_malloc (ntohs (msg->size));
+ req = (const struct GNUNET_DNS_Request *) msg;
+ GNUNET_break (ntohl (req->reserved) == 0);
+ payload_length = ntohs (req->header.size) - sizeof (struct GNUNET_DNS_Request);
+ GNUNET_CLIENT_receive (dh->dns_connection,
+ &request_handler, dh,
+ GNUNET_TIME_UNIT_FOREVER_REL);
- memcpy (pkt, msg, ntohs (msg->size));
+ /* finally, pass request to callback for answers */
+ rh = GNUNET_malloc (sizeof (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]);
+}
- GNUNET_SCHEDULER_add_now (h->process_answer_cb, pkt);
- GNUNET_CLIENT_receive (h->dns_connection, &dns_answer_handler, h,
- GNUNET_TIME_UNIT_FOREVER_REL);
+
+/**
+ * Callback called by notify_transmit_ready; sends DNS replies
+ * to the DNS service.
+ *
+ * @param cls the struct GNUNET_DNS_Handle
+ * @param size number of bytes available in buf
+ * @param buf where to copy the message for transmission
+ * @return number of bytes copied to buf
+ */
+static size_t
+send_response (void *cls, size_t size, void *buf)
+{
+ struct GNUNET_DNS_Handle *dh = cls;
+ struct ReplyQueueEntry *qe;
+ size_t len;
+
+ dh->dns_transmit_handle = NULL;
+ if (NULL == buf)
+ {
+ disconnect (dh);
+ dh->reconnect_task =
+ GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
+ &reconnect, dh);
+ return 0;
+ }
+ qe = dh->rq_head;
+ if (NULL == qe)
+ return 0;
+ len = ntohs (qe->msg->size);
+ if (len > size)
+ {
+ dh->dns_transmit_handle =
+ GNUNET_CLIENT_notify_transmit_ready (dh->dns_connection,
+ len,
+ GNUNET_TIME_UNIT_FOREVER_REL,
+ GNUNET_NO,
+ &send_response, dh);
+ return 0;
+ }
+ memcpy (buf, qe->msg, len);
+ GNUNET_CONTAINER_DLL_remove (dh->rq_head,
+ dh->rq_tail,
+ qe);
+ GNUNET_free (qe);
+ if (GNUNET_NO == dh->in_receive)
+ {
+ dh->in_receive = GNUNET_YES;
+ GNUNET_CLIENT_receive (dh->dns_connection,
+ &request_handler, dh,
+ GNUNET_TIME_UNIT_FOREVER_REL);
+ }
+ if (NULL != (qe = dh->rq_head))
+ {
+ dh->dns_transmit_handle =
+ GNUNET_CLIENT_notify_transmit_ready (dh->dns_connection,
+ ntohs (qe->msg->size),
+ GNUNET_TIME_UNIT_FOREVER_REL,
+ GNUNET_NO,
+ &send_response, dh);
+ }
+ return len;
+}
+
+
+/**
+ * Add the given reply to our transmission queue and trigger sending if needed.
+ *
+ * @param dh handle with the connection
+ * @param qe reply to queue
+ */
+static void
+queue_reply (struct GNUNET_DNS_Handle *dh,
+ struct ReplyQueueEntry *qe)
+{
+ if (NULL == dh->dns_connection)
+ {
+ GNUNET_free (qe);
+ return;
+ }
+ GNUNET_CONTAINER_DLL_insert_tail (dh->rq_head,
+ dh->rq_tail,
+ qe);
+ if (NULL != dh->dns_transmit_handle)
+ return;
+ /* trigger sending */
+ dh->dns_transmit_handle =
+ GNUNET_CLIENT_notify_transmit_ready (dh->dns_connection,
+ ntohs (dh->rq_head->msg->size),
+ GNUNET_TIME_UNIT_FOREVER_REL,
+ GNUNET_NO,
+ &send_response, dh);
}
/**
- * Connect to the service-dns
+ * If a GNUNET_DNS_RequestHandler calls this function, the request is
+ * given to other clients or the global DNS for resolution. 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.
+ *
+ * @param rh request that should now be forwarded
*/
-struct GNUNET_DNS_Handle *
-GNUNET_DNS_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
- GNUNET_SCHEDULER_Task cb,
- void *cb_cls)
+void
+GNUNET_DNS_request_forward (struct GNUNET_DNS_RequestHandle *rh)
{
- struct GNUNET_DNS_Handle *h;
-
- h = GNUNET_malloc (sizeof (struct GNUNET_DNS_Handle));
- h->cfg = cfg;
- h->process_answer_cb = cb;
- h->process_answer_cb_cls = cb_cls;
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Connecting to service-dns\n");
- h->dns_connection = GNUNET_CLIENT_connect ("dns", h->cfg);
- /* This would most likely be a misconfiguration */
- GNUNET_assert (NULL != h->dns_connection);
- GNUNET_CLIENT_receive (h->dns_connection,
- &dns_answer_handler, NULL,
- GNUNET_TIME_UNIT_FOREVER_REL);
- /* If a packet is already in the list, schedule to send it */
- if (h->dns_transmit_handle == NULL && h->head != NULL)
- h->dns_transmit_handle =
- GNUNET_CLIENT_notify_transmit_ready (h->dns_connection,
- ntohs (h->head->pkt.hdr.size),
- GNUNET_TIME_UNIT_FOREVER_REL,
- GNUNET_YES, &send_query, h);
- else if (h->dns_transmit_handle == NULL && h->restart_hijack == 1)
+ struct ReplyQueueEntry *qe;
+ struct GNUNET_DNS_Response *resp;
+
+ GNUNET_assert (0 < rh->dh->pending_requests--);
+ if (rh->generation != rh->dh->generation)
{
- h->dns_transmit_handle =
- GNUNET_CLIENT_notify_transmit_ready (h->dns_connection,
- sizeof (struct
- GNUNET_MessageHeader),
- GNUNET_TIME_UNIT_FOREVER_REL,
- GNUNET_YES, &send_query, NULL);
+ GNUNET_free (rh);
+ return;
}
- return h;
+ qe = GNUNET_malloc (sizeof (struct ReplyQueueEntry) +
+ sizeof (struct GNUNET_DNS_Response));
+ resp = (struct GNUNET_DNS_Response*) &qe[1];
+ qe->msg = &resp->header;
+ resp->header.size = htons (sizeof (struct GNUNET_DNS_Response));
+ resp->header.type = htons (GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE);
+ resp->drop_flag = htonl (1);
+ resp->request_id = rh->request_id;
+ queue_reply (rh->dh, qe);
+ GNUNET_free (rh);
}
+/**
+ * If a GNUNET_DNS_RequestHandler calls this function, the request is
+ * to be dropped and no response should be generated.
+ *
+ * @param rh request that should now be dropped
+ */
void
-GNUNET_DNS_restart_hijack (struct GNUNET_DNS_Handle *h)
+GNUNET_DNS_request_drop (struct GNUNET_DNS_RequestHandle *rh)
{
- h->restart_hijack = 1;
- if (NULL != h->dns_connection && h->dns_transmit_handle == NULL)
- h->dns_transmit_handle =
- GNUNET_CLIENT_notify_transmit_ready (h->dns_connection,
- sizeof (struct
- GNUNET_MessageHeader),
- GNUNET_TIME_UNIT_FOREVER_REL,
- GNUNET_YES, &send_query, h);
+ struct ReplyQueueEntry *qe;
+ struct GNUNET_DNS_Response *resp;
+
+ GNUNET_assert (0 < rh->dh->pending_requests--);
+ if (rh->generation != rh->dh->generation)
+ {
+ GNUNET_free (rh);
+ return;
+ }
+ qe = GNUNET_malloc (sizeof (struct ReplyQueueEntry) +
+ sizeof (struct GNUNET_DNS_Response));
+ resp = (struct GNUNET_DNS_Response*) &qe[1];
+ qe->msg = &resp->header;
+ resp->header.size = htons (sizeof (struct GNUNET_DNS_Response));
+ resp->header.type = htons (GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE);
+ resp->request_id = rh->request_id;
+ resp->drop_flag = htonl (0);
+ queue_reply (rh->dh, qe);
+ GNUNET_free (rh);
}
/**
- * FIXME: we should not expost our internal structures like this.
- * Just a quick initial hack.
+ * 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).
+ *
+ * @param rh request that should now be answered
+ * @param reply_length size of reply (uint16_t to force sane size)
+ * @param reply reply data
*/
void
-GNUNET_DNS_queue_request (struct GNUNET_DNS_Handle *h,
- struct query_packet_list *q)
+GNUNET_DNS_request_answer (struct GNUNET_DNS_RequestHandle *rh,
+ uint16_t reply_length,
+ const char *reply)
{
- GNUNET_CONTAINER_DLL_insert_tail (h->head, h->tail, q);
- if (h->dns_connection != NULL && h->dns_transmit_handle == NULL)
- h->dns_transmit_handle =
- GNUNET_CLIENT_notify_transmit_ready (h->dns_connection, ntohs(q->pkt.hdr.size),
- GNUNET_TIME_UNIT_FOREVER_REL,
- GNUNET_YES, &send_query,
- h);
+ struct ReplyQueueEntry *qe;
+ 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_SERVER_MAX_MESSAGE_SIZE)
+ {
+ GNUNET_break (0);
+ GNUNET_free (rh);
+ return;
+ }
+ qe = GNUNET_malloc (sizeof (struct ReplyQueueEntry) +
+ sizeof (struct GNUNET_DNS_Response) + reply_length);
+ resp = (struct GNUNET_DNS_Response*) &qe[1];
+ qe->msg = &resp->header;
+ resp->header.size = htons (sizeof (struct GNUNET_DNS_Response) + reply_length);
+ resp->header.type = htons (GNUNET_MESSAGE_TYPE_DNS_CLIENT_RESPONSE);
+ resp->drop_flag = htonl (2);
+ resp->request_id = rh->request_id;
+ memcpy (&resp[1], reply, reply_length);
+ queue_reply (rh->dh, qe);
+ GNUNET_free (rh);
+}
+
+
+/**
+ * Connect to the service-dns
+ *
+ * @param cfg configuration to use
+ * @param flags when to call rh
+ * @param rh function to call with DNS requests
+ * @param rh_cls closure to pass to rh
+ * @return DNS handle
+ */
+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)
+{
+ struct GNUNET_DNS_Handle *dh;
+
+ dh = GNUNET_malloc (sizeof (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;
}
+/**
+ * Disconnect from the DNS service.
+ *
+ * @param dh DNS handle
+ */
void
-GNUNET_DNS_disconnect (struct GNUNET_DNS_Handle *h)
+GNUNET_DNS_disconnect (struct GNUNET_DNS_Handle *dh)
{
- if (h->dns_connection != NULL)
+ if (GNUNET_SCHEDULER_NO_TASK != dh->reconnect_task)
{
- GNUNET_CLIENT_disconnect (h->dns_connection, GNUNET_NO);
- h->dns_connection = NULL;
+ GNUNET_SCHEDULER_cancel (dh->reconnect_task);
+ dh->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
}
- GNUNET_free (h);
+ disconnect (dh);
+ /* make sure client has no pending requests left over! */
+ GNUNET_assert (0 == dh->pending_requests);
+ GNUNET_free (dh);
}
+
+/* end of dns_api_new.c */