/*

  Linux DNS client library implementation

  Copyright (C) 2006 Krishna Ganugapati <krishnag@centeris.com>

  Copyright (C) 2006 Gerald Carter <jerry@samba.org>

     ** NOTE! The following LGPL license applies to the libaddns

     ** library. This does NOT imply that all of Samba is released

     ** under the LGPL

  This library is free software; you can redistribute it and/or

  modify it under the terms of the GNU Lesser General Public

  License as published by the Free Software Foundation; either

  version 2.1 of the License, or (at your option) any later version.

  This library 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

  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public

  License along with this library; if not, see <http://www.gnu.org/licenses/>.

*/

#include "replace.h"

#include "dns.h"

#include <sys/time.h>

#include <unistd.h>

#include "system/select.h"

#include "../lib/util/debug.h"

static int destroy_dns_connection(struct dns_connection *conn)

{

  return close(conn->s);

}

/********************************************************************

********************************************************************/

static DNS_ERROR dns_open_helper(const char *nameserver,

         const char *service,

         struct addrinfo *hints,

         TALLOC_CTX *mem_ctx,

         struct dns_connection **ret_conn)

{

  int ret;

  struct addrinfo *rp;

  struct addrinfo *ai_result = NULL;

  struct dns_connection *conn = NULL;

  if (!(conn = talloc(mem_ctx, struct dns_connection))) {

    return ERROR_DNS_NO_MEMORY;

  }

  ret = getaddrinfo(nameserver, service, hints, &ai_result);

  if (ret != 0) {

    DEBUG(1,("dns_tcp_open: getaddrinfo: %s\n", gai_strerror(ret)));

    TALLOC_FREE(conn);

    return ERROR_DNS_INVALID_NAME_SERVER;

  }

  for (rp = ai_result; rp != NULL; rp = rp->ai_next) {

    conn->s = socket(rp->ai_family,

        rp->ai_socktype,

        rp->ai_protocol);

    if (conn->s == -1) {

      continue;

    }

    do {

      ret = connect(conn->s, rp->ai_addr, rp->ai_addrlen);

    } while ((ret == -1) && (errno == EINTR));

    if (ret != -1) {

      /* Successful connect */

      break;

    }

    close(conn->s);

  }

  freeaddrinfo(ai_result);

  if (rp == NULL) {

    TALLOC_FREE(conn);

    return ERROR_DNS_CONNECTION_FAILED;

  }

  talloc_set_destructor(conn, destroy_dns_connection);

  *ret_conn = conn;

  return ERROR_DNS_SUCCESS;

}

static DNS_ERROR dns_tcp_open( const char *nameserver,

             TALLOC_CTX *mem_ctx,

             struct dns_connection **result )

{

  struct addrinfo hints;

  struct dns_connection *conn;

  DNS_ERROR dns_ret;

  char service[16];

  snprintf(service, sizeof(service), "%d", DNS_TCP_PORT);

  memset(&hints, 0, sizeof(struct addrinfo));

  hints.ai_family = AF_UNSPEC;

  hints.ai_socktype = SOCK_STREAM;

  hints.ai_flags = 0;

  hints.ai_protocol = IPPROTO_TCP;

  dns_ret = dns_open_helper(nameserver, service, &hints, mem_ctx, &conn);

  if (!ERR_DNS_IS_OK(dns_ret)) {

    return dns_ret;

  }

  conn->hType = DNS_TCP;

  *result = conn;

  return ERROR_DNS_SUCCESS;

}

/********************************************************************

 * ********************************************************************/

static DNS_ERROR dns_udp_open( const char *nameserver,

             TALLOC_CTX *mem_ctx,

             struct dns_connection **result )

{

  struct addrinfo hints;

  struct sockaddr_storage RecvAddr;

  struct dns_connection *conn = NULL;

  DNS_ERROR dns_ret;

  socklen_t RecvAddrLen;

  char service[16];

  snprintf(service, sizeof(service), "%d", DNS_UDP_PORT);

  memset(&hints, 0, sizeof(struct addrinfo));

  hints.ai_family = AF_UNSPEC;

  hints.ai_socktype = SOCK_DGRAM;

  hints.ai_flags = 0;

  hints.ai_protocol = IPPROTO_UDP;

  dns_ret = dns_open_helper(nameserver, service, &hints, mem_ctx, &conn);

  if (!ERR_DNS_IS_OK(dns_ret)) {

    TALLOC_FREE(conn);

    return dns_ret;

  }

  /* Set up the RecvAddr structure with the IP address of

     the receiver and the specified port number. */

  RecvAddrLen = sizeof(RecvAddr);

  if (getpeername(conn->s,

      (struct sockaddr *)&RecvAddr,

      &RecvAddrLen) == -1) {

    return ERROR_DNS_CONNECTION_FAILED;

  }

  conn->hType = DNS_UDP;

  memcpy(&conn->RecvAddr, &RecvAddr, sizeof(struct sockaddr_storage));

  *result = conn;

  return ERROR_DNS_SUCCESS;

}

/********************************************************************

********************************************************************/

DNS_ERROR dns_open_connection( const char *nameserver, int32_t dwType,

        TALLOC_CTX *mem_ctx,

        struct dns_connection **conn )

{

  switch ( dwType ) {

  case DNS_TCP:

    return dns_tcp_open( nameserver, mem_ctx, conn );

  case DNS_UDP:

    return dns_udp_open( nameserver, mem_ctx, conn );

  }

  return ERROR_DNS_INVALID_PARAMETER;

}

static DNS_ERROR write_all(int fd, uint8_t *data, size_t len)

{

  size_t total = 0;

  while (total < len) {

    ssize_t ret;

    do {

      ret = write(fd, data + total, len - total);

    } while ((ret == -1) && (errno == EINTR));

    if (ret <= 0) {

      /*

       * EOF or error

       */

      return ERROR_DNS_SOCKET_ERROR;

    }

    total += ret;

  }

  return ERROR_DNS_SUCCESS;

}

static DNS_ERROR dns_send_tcp(struct dns_connection *conn,

            const struct dns_buffer *buf)

{

  uint16_t len = htons(buf->offset);

  DNS_ERROR err;

  err = write_all(conn->s, (uint8_t *)&len, sizeof(len));

  if (!ERR_DNS_IS_OK(err)) return err;

  return write_all(conn->s, buf->data, buf->offset);

}

static DNS_ERROR dns_send_udp(struct dns_connection *conn,

            const struct dns_buffer *buf)

{

  ssize_t ret;

  do {

    ret = send(conn->s, buf->data, buf->offset, 0);

  } while ((ret == -1) && (errno == EINTR));

  if (ret != buf->offset) {

    return ERROR_DNS_SOCKET_ERROR;

  }

  return ERROR_DNS_SUCCESS;

}

DNS_ERROR dns_send(struct dns_connection *conn, const struct dns_buffer *buf)

{

  if (conn->hType == DNS_TCP) {

    return dns_send_tcp(conn, buf);

  }

  if (conn->hType == DNS_UDP) {

    return dns_send_udp(conn, buf);

  }

  return ERROR_DNS_INVALID_PARAMETER;

}

static DNS_ERROR read_all(int fd, uint8_t *data, size_t len)

{

  size_t total = 0;

  while (total < len) {

    struct pollfd pfd;

    ssize_t ret;

    int fd_ready;

    ZERO_STRUCT(pfd);

    pfd.fd = fd;

    pfd.events = POLLIN|POLLHUP;

    fd_ready = poll(&pfd, 1, 10000);

    if (fd_ready == -1) {

      if (errno == EINTR) {

        continue;

      }

      return ERROR_DNS_SOCKET_ERROR;

    }

    if ( fd_ready == 0 ) {

      /* read timeout */

      return ERROR_DNS_SOCKET_ERROR;

    }

    do {

      ret = read(fd, data + total, len - total);

    } while ((ret == -1) && (errno == EINTR));

    if (ret <= 0) {

      /* EOF or error */

      return ERROR_DNS_SOCKET_ERROR;

    }

    total += ret;

  }

  return ERROR_DNS_SUCCESS;

}

static DNS_ERROR dns_receive_tcp(TALLOC_CTX *mem_ctx,

         struct dns_connection *conn,

         struct dns_buffer **presult)

{

  struct dns_buffer *buf;

  DNS_ERROR err;

  uint16_t len;

  if (!(buf = talloc_zero(mem_ctx, struct dns_buffer))) {

    return ERROR_DNS_NO_MEMORY;

  }

  err = read_all(conn->s, (uint8_t *)&len, sizeof(len));

  if (!ERR_DNS_IS_OK(err)) {

    return err;

  }

  buf->size = ntohs(len);

  if (buf->size == 0) {

    *presult = buf;

    return ERROR_DNS_SUCCESS;

  }

  if (!(buf->data = talloc_array(buf, uint8_t, buf->size))) {

    TALLOC_FREE(buf);

    return ERROR_DNS_NO_MEMORY;

  }

  err = read_all(conn->s, buf->data, talloc_get_size(buf->data));

  if (!ERR_DNS_IS_OK(err)) {

    TALLOC_FREE(buf);

    return err;

  }

  *presult = buf;

  return ERROR_DNS_SUCCESS;

}

static DNS_ERROR dns_receive_udp(TALLOC_CTX *mem_ctx,

         struct dns_connection *conn,

         struct dns_buffer **presult)

{

  struct dns_buffer *buf;

  ssize_t received;

  if (!(buf = talloc_zero(mem_ctx, struct dns_buffer))) {

    return ERROR_DNS_NO_MEMORY;

  }

  /*

   * UDP based DNS can only be 512 bytes

   */

  if (!(buf->data = talloc_array(buf, uint8_t, 512))) {

    TALLOC_FREE(buf);

    return ERROR_DNS_NO_MEMORY;

  }

  do {

    received = recv(conn->s, (void *)buf->data, 512, 0);

  } while ((received == -1) && (errno == EINTR));

  if (received == -1) {

    TALLOC_FREE(buf);

    return ERROR_DNS_SOCKET_ERROR;

  }

  if (received > 512) {

    TALLOC_FREE(buf);

    return ERROR_DNS_BAD_RESPONSE;

  }

  buf->size = received;

  buf->offset = 0;

  *presult = buf;

  return ERROR_DNS_SUCCESS;

}

DNS_ERROR dns_receive(TALLOC_CTX *mem_ctx, struct dns_connection *conn,

          struct dns_buffer **presult)

{

  if (conn->hType == DNS_TCP) {

    return dns_receive_tcp(mem_ctx, conn, presult);

  }

  if (conn->hType == DNS_UDP) {

    return dns_receive_udp(mem_ctx, conn, presult);

  }

  return ERROR_DNS_INVALID_PARAMETER;

}

DNS_ERROR dns_transaction(TALLOC_CTX *mem_ctx, struct dns_connection *conn,

        const struct dns_request *req,

        struct dns_request **resp)

{

  struct dns_buffer *buf = NULL;

  DNS_ERROR err;

  err = dns_marshall_request(mem_ctx, req, &buf);

  if (!ERR_DNS_IS_OK(err)) goto error;

  err = dns_send(conn, buf);

  if (!ERR_DNS_IS_OK(err)) goto error;

  TALLOC_FREE(buf);

  err = dns_receive(mem_ctx, conn, &buf);

  if (!ERR_DNS_IS_OK(err)) goto error;

  err = dns_unmarshall_request(mem_ctx, buf, resp);

 error:

  TALLOC_FREE(buf);

  return err;

}

DNS_ERROR dns_update_transaction(TALLOC_CTX *mem_ctx,

         struct dns_connection *conn,

         struct dns_update_request *up_req,

         struct dns_update_request **up_resp)

{

  struct dns_request *resp;

  DNS_ERROR err;

  err = dns_transaction(mem_ctx, conn, dns_update2request(up_req),

            &resp);

  if (!ERR_DNS_IS_OK(err)) return err;

  *up_resp = dns_request2update(resp);

  return ERROR_DNS_SUCCESS;

}