source: mainline/uspace/srv/net/dnsrsrv/transport.c@ f93ba6d5

/*
 * Copyright (c) 2013 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup dnsres
 * @{
 */
/**
 * @file
 */

#include <adt/list.h>
#include <errno.h>
#include <fibril_synch.h>
#include <io/log.h>
#include <net/in.h>
#include <net/inet.h>
#include <net/socket.h>
#include <stdbool.h>
#include <stdlib.h>

#include "dns_msg.h"
#include "dns_type.h"
#include "transport.h"

#define RECV_BUF_SIZE 4096
#define DNS_SERVER_PORT 53

/** Request timeout (microseconds) */
#define REQ_TIMEOUT (5 * 1000 * 1000)

/** Maximum number of retries */
#define REQ_RETRY_MAX 3

inet_addr_t dns_server_addr;

typedef struct {
        link_t lreq;
        dns_message_t *req;
        dns_message_t *resp;

        bool done;
        fibril_condvar_t done_cv;
        fibril_mutex_t done_lock;

        int status;
} trans_req_t;

static uint8_t recv_buf[RECV_BUF_SIZE];
static fid_t recv_fid;
static int transport_fd = -1;

/** Outstanding requests */
static LIST_INITIALIZE(treq_list);
static FIBRIL_MUTEX_INITIALIZE(treq_lock);

static int transport_recv_fibril(void *arg);

int transport_init(void)
{
        struct sockaddr_in laddr;
        int fd;
        fid_t fid;
        int rc;

        laddr.sin_family = AF_INET;
        laddr.sin_port = htons(12345);
        laddr.sin_addr.s_addr = INADDR_ANY;

        fd = -1;

        fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
        if (fd < 0) {
                rc = EIO;
                goto error;
        }

        rc = bind(fd, (struct sockaddr *)&laddr, sizeof(laddr));
        if (rc != EOK)
                goto error;

        transport_fd = fd;

        fid = fibril_create(transport_recv_fibril, NULL);
        if (fid == 0)
                goto error;

        fibril_add_ready(fid);
        recv_fid = fid;
        return EOK;
error:
        log_msg(LOG_DEFAULT, LVL_ERROR, "Failed initializing network socket.");
        if (fd >= 0)
                closesocket(fd);
        return rc;
}

void transport_fini(void)
{
        if (transport_fd >= 0)
                closesocket(transport_fd);
}

static trans_req_t *treq_create(dns_message_t *req)
{
        trans_req_t *treq;

        treq = calloc(1, sizeof(trans_req_t));
        if (treq == NULL)
                return NULL;

        treq->req = req;
        treq->resp = NULL;
        treq->done = false;
        fibril_condvar_initialize(&treq->done_cv);
        fibril_mutex_initialize(&treq->done_lock);

        fibril_mutex_lock(&treq_lock);
        list_append(&treq->lreq, &treq_list);
        fibril_mutex_unlock(&treq_lock);

        return treq;
}

static void treq_destroy(trans_req_t *treq)
{
        if (link_in_use(&treq->lreq))
                list_remove(&treq->lreq);
        free(treq);
}

static trans_req_t *treq_match_resp(dns_message_t *resp)
{
        assert(fibril_mutex_is_locked(&treq_lock));

        list_foreach(treq_list, lreq, trans_req_t, treq) {
                if (treq->req->id == resp->id) {
                        /* Match */
                        return treq;
                }
        }

        return NULL;
}

static void treq_complete(trans_req_t *treq, dns_message_t *resp)
{
        fibril_mutex_lock(&treq->done_lock);
        treq->done = true;
        treq->status = EOK;
        treq->resp = resp;
        fibril_mutex_unlock(&treq->done_lock);

        fibril_condvar_broadcast(&treq->done_cv);
}

int dns_request(dns_message_t *req, dns_message_t **rresp)
{
        trans_req_t *treq = NULL;
        struct sockaddr *saddr = NULL;
        socklen_t saddrlen;
        
        void *req_data;
        size_t req_size;
        int rc = dns_message_encode(req, &req_data, &req_size);
        if (rc != EOK)
                goto error;
        
        rc = inet_addr_sockaddr(&dns_server_addr, DNS_SERVER_PORT,
            &saddr, &saddrlen);
        if (rc != EOK) {
                assert(rc == ENOMEM);
                goto error;
        }
        
        size_t ntry = 0;
        
        while (ntry < REQ_RETRY_MAX) {
                rc = sendto(transport_fd, req_data, req_size, 0,
                    saddr, saddrlen);
                if (rc != EOK)
                        goto error;
                
                treq = treq_create(req);
                if (treq == NULL) {
                        rc = ENOMEM;
                        goto error;
                }
                
                fibril_mutex_lock(&treq->done_lock);
                while (treq->done != true) {
                        rc = fibril_condvar_wait_timeout(&treq->done_cv, &treq->done_lock,
                            REQ_TIMEOUT);
                        if (rc == ETIMEOUT) {
                                ++ntry;
                                break;
                        }
                }
                
                fibril_mutex_unlock(&treq->done_lock);
                
                if (rc != ETIMEOUT)
                        break;
        }
        
        if (ntry >= REQ_RETRY_MAX) {
                rc = EIO;
                goto error;
        }
        
        if (treq->status != EOK) {
                rc = treq->status;
                goto error;
        }
        
        *rresp = treq->resp;
        treq_destroy(treq);
        free(req_data);
        free(saddr);
        return EOK;
        
error:
        if (treq != NULL)
                treq_destroy(treq);
        
        free(req_data);
        free(saddr);
        return rc;
}

static int transport_recv_msg(dns_message_t **rresp)
{
        struct sockaddr_in src_addr;
        socklen_t src_addr_size;
        size_t recv_size;
        dns_message_t *resp;
        int rc;

        src_addr_size = sizeof(src_addr);
        rc = recvfrom(transport_fd, recv_buf, RECV_BUF_SIZE, 0,
            (struct sockaddr *)&src_addr, &src_addr_size);
        if (rc < 0) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "recvfrom returns error - %d", rc);
                goto error;
        }

        recv_size = (size_t)rc;

        rc = dns_message_decode(recv_buf, recv_size, &resp);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        *rresp = resp;
        return EOK;

error:
        return rc;
}

static int transport_recv_fibril(void *arg)
{
        dns_message_t *resp = NULL;
        trans_req_t *treq;
        int rc;

        while (true) {
                rc = transport_recv_msg(&resp);
                if (rc != EOK)
                        continue;

                assert(resp != NULL);

                fibril_mutex_lock(&treq_lock);
                treq = treq_match_resp(resp);
                if (treq == NULL) {
                        fibril_mutex_unlock(&treq_lock);
                        continue;
                }

                list_remove(&treq->lreq);
                fibril_mutex_unlock(&treq_lock);

                treq_complete(treq, resp);
        }

        return 0;
}

/** @}
 */