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//=============================================================================

//

//      dns.c

//

//      DNS client code

//

//=============================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos 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.

//

// eCos 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 eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

// in accordance with section (3) of the GNU General Public License.

//

// This exception does not invalidate any other reasons why a work based on

// this file might be covered by the GNU General Public License.

//

// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

// -------------------------------------------

//####ECOSGPLCOPYRIGHTEND####

//=============================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):   andrew.lunn

// Contributors:andrew.lunn, jskov

// Date:        2001-09-18

// Description: Provides DNS lookup as per RFC 1034/1035.

// 

// Note:        Does only support A and PTR lookups. Maybe add for other

//              types as well?

//

//              parse_answer() only returns the first found record.

//

//              Add tracing and assertions.

//

//####DESCRIPTIONEND####

//

//=============================================================================

#include <pkgconf/system.h>

#ifdef CYGPKG_KERNEL

# include <pkgconf/kernel.h>

# include <cyg/kernel/kapi.h>

#endif

#include <cyg/hal/drv_api.h>

#include <cyg/infra/cyg_type.h>

#include <cyg/infra/cyg_trac.h>         /* Tracing support */

#include <netdb.h>

#include <sys/time.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <arpa/inet.h>

#include <ctype.h>

#include <unistd.h>

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <cyg/ns/dns/dns_priv.h>

static short id = 0;              /* ID of the last query */

static int s = -1;                /* Socket to the DNS server */

static cyg_drv_mutex_t dns_mutex; /* Mutex to stop multiple queries as once */

static cyg_ucount32 ptdindex;     /* Index for the per thread data */

static char * domainname=NULL;    /* Domain name used for queries */

/* Allocate space for string of length len. Return NULL on failure. */

static inline char*

alloc_string(int len)

{

    return malloc(len);

}

static inline void

free_string(char* s)

{

    free(s);

}

/* Deallocate the memory taken to hold a hent structure */

static void

free_hent(struct hostent * hent)

{

    if (hent->h_name) {

        free_string(hent->h_name);

    }

    if (hent->h_addr_list) {

        int i = 0;

        while (hent->h_addr_list[i]) {

            free(hent->h_addr_list[i]);

            i++;

        }

        free(hent->h_addr_list);

    }

    free(hent);

}

/* Allocate hent structure with room for one in_addr. Returns NULL on

   failure. */

static struct hostent*

alloc_hent(void)

{

    struct hostent *hent;

    hent = malloc(sizeof(struct hostent));

    if (hent) {

        memset(hent, 0, sizeof(struct hostent));

        hent->h_addr_list = malloc(sizeof(char *)*2);

        if (!hent->h_addr_list) {

            free_hent(hent);

            return NULL;

        }

        hent->h_addr_list[0] = malloc(sizeof(struct in_addr));

        if (!hent->h_addr_list[0]) {

            free_hent(hent);

            return NULL;

        }

        hent->h_addr_list[1] = NULL;

    }

    return hent;

}

/* Thread destructor used to free stuff stored in per-thread data slot. */

static void

thread_destructor(CYG_ADDRWORD data)

{

    struct hostent *hent;

    hent = (struct hostent *)cyg_thread_get_data(ptdindex);

    if (hent)

        free_hent(hent);

    return;

    data=data;

}

/* Store the hent away in the per-thread data. */

static void

store_hent(struct hostent *hent)

{

    // Prevent memory leaks by setting a destructor to be

    // called on thread exit to free per-thread data.

    cyg_thread_add_destructor( &thread_destructor, 0 );

    cyg_thread_set_data(ptdindex, (CYG_ADDRWORD)hent);

}

/* If there is an answer to an old query, free the memory it uses. */

static void

free_stored_hent(void)

{

    struct hostent *hent;

    hent = (struct hostent *)cyg_thread_get_data(ptdindex);

    if (hent) {

        free_hent(hent);

        cyg_thread_set_data(ptdindex, (CYG_ADDRWORD)NULL);

        cyg_thread_rem_destructor( &thread_destructor, 0 );

    }

}

/* Send the query to the server and read the response back. Return -1

   if it fails, otherwise put the response back in msg and return the

   length of the response. */

static int

send_recv(char * msg, int len, int msglen)

{

    struct dns_header *dns_hdr;

    struct timeval timeout;

    int finished = false;

    int backoff = 1;

    fd_set readfds;

    int written;

    int ret;

    CYG_REPORT_FUNCNAMETYPE( "send_recv", "returning %d" );

    CYG_REPORT_FUNCARG3( "msg=%08x, len=%d, msglen", msg, len, msglen );

    CYG_CHECK_DATA_PTR( msg, "msg is not a valid pointer!" );

    dns_hdr = (struct dns_header *) msg;

    do {

        written = write(s, msg, len);

        if (written < 0) {

            ret = -1;

            break;

        }

        FD_ZERO(&readfds);

        FD_SET(s, &readfds);

        timeout.tv_sec = backoff;

        timeout.tv_usec = 0;

        backoff = backoff << 1;

        ret = select(s+1, &readfds, NULL, NULL, &timeout);

        if (ret < 0) {

            ret = -1;

            break;

        }

        /* Timeout */

        if (ret == 0) {

            if (backoff > 16) {

                h_errno = TRY_AGAIN;

                ret = -1;

                break;

            }

        }

        if (ret == 1) {

            ret = read(s, msg, msglen);

            if (ret < 0) {

                ret = -1;

                break;

            }

            /* Reply to an old query. Ignore it */

            if (ntohs(dns_hdr->id) != (id-1)) {

                continue;

            }

            finished = true;

        }

    } while (!finished);

    CYG_REPORT_RETVAL( ret );

    return ret;

}

/* Include the DNS client implementation code */

#include <cyg/ns/dns/dns_impl.inl>

/* Initialise the resolver. Open a socket and bind it to the address

   of the server.  return -1 if something goes wrong, otherwise 0. If

   we are being called a second time we have to be careful to allow

   any ongoing lookups to finish before we close the socket and

   connect to a different DNS server. The danger here is that we may

   have to wait for upto 32 seconds if the DNS server is down.

 */

int

cyg_dns_res_init(struct in_addr *dns_server)

{

    struct sockaddr_in server;

    struct servent *sent;

    static int init =0;

    CYG_REPORT_FUNCNAMETYPE( "cyg_dns_res_init", "returning %d" );

    CYG_REPORT_FUNCARG1( "dns_server=%08x", dns_server );

    CYG_CHECK_DATA_PTR( dns_server, "dns_server is not a valid pointer!" );

    if (init) {

      cyg_drv_mutex_lock(&dns_mutex);

      cyg_thread_free_data_index(ptdindex);

      if (s >= 0) {

        close(s);

      }

    } else {

      init = 1;

      cyg_drv_mutex_init(&dns_mutex);

      cyg_drv_mutex_lock(&dns_mutex);

    }

    s = socket(PF_INET, SOCK_DGRAM, 0);

    if (s < 0) {

        cyg_drv_mutex_unlock(&dns_mutex);

        CYG_REPORT_RETVAL( -1 );

        return -1;

    }

    sent = getservbyname("domain", "udp");

    if (sent == (struct servent *)0) {

        s = -1;

        cyg_drv_mutex_unlock(&dns_mutex);

        CYG_REPORT_RETVAL( -1 );

        return -1;

    }

    memcpy((char *)&server.sin_addr, dns_server, sizeof(server.sin_addr));

    server.sin_port = sent->s_port;

    server.sin_family = AF_INET;

    server.sin_len = sizeof(server);

    if (connect(s, (struct sockaddr *)&server, sizeof(server)) < 0) {

        s = -1;

        cyg_drv_mutex_unlock(&dns_mutex);

        CYG_REPORT_RETVAL( -1 );

        return -1;

    }

    ptdindex = cyg_thread_new_data_index();

    cyg_drv_mutex_unlock(&dns_mutex);

    CYG_REPORT_RETVAL( 0 );

    return 0;

}