libaddns/dnssock.c

説明を見る。

/*
  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, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  
  02110-1301  USA
*/

#include "dns.h"
#include <sys/time.h>
#include <unistd.h>

static int destroy_dns_connection(struct dns_connection *conn)
{
        return close(conn->s);
}

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

static DNS_ERROR dns_tcp_open( const char *nameserver,
                               TALLOC_CTX *mem_ctx,
                               struct dns_connection **result )
{
        uint32_t ulAddress;
        struct hostent *pHost;
        struct sockaddr_in s_in;
        struct dns_connection *conn;
        int res;

        if (!(conn = talloc(mem_ctx, struct dns_connection))) {
                return ERROR_DNS_NO_MEMORY;
        }

        if ( (ulAddress = inet_addr( nameserver )) == INADDR_NONE ) {
                if ( (pHost = gethostbyname( nameserver )) == NULL ) {
                        TALLOC_FREE(conn);
                        return ERROR_DNS_INVALID_NAME_SERVER;
                }
                memcpy( &ulAddress, pHost->h_addr, pHost->h_length );
        }

        conn->s = socket( PF_INET, SOCK_STREAM, 0 );
        if (conn->s == -1) {
                TALLOC_FREE(conn);
                return ERROR_DNS_CONNECTION_FAILED;
        }

        talloc_set_destructor(conn, destroy_dns_connection);

        s_in.sin_family = AF_INET;
        s_in.sin_addr.s_addr = ulAddress;
        s_in.sin_port = htons( DNS_TCP_PORT );

        res = connect(conn->s, (struct sockaddr*)&s_in, sizeof( s_in ));
        if (res == -1) {
                TALLOC_FREE(conn);
                return ERROR_DNS_CONNECTION_FAILED;
        }

        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 )
{
        unsigned long ulAddress;
        struct hostent *pHost;
        struct sockaddr_in RecvAddr;
        struct dns_connection *conn;

        if (!(conn = talloc(NULL, struct dns_connection))) {
                return ERROR_DNS_NO_MEMORY;
        }

        if ( (ulAddress = inet_addr( nameserver )) == INADDR_NONE ) {
                if ( (pHost = gethostbyname( nameserver )) == NULL ) {
                        TALLOC_FREE(conn);
                        return ERROR_DNS_INVALID_NAME_SERVER;
                }
                memcpy( &ulAddress, pHost->h_addr, pHost->h_length );
        }
        
        /* Create a socket for sending data */

        conn->s = socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
        if (conn->s == -1) {
                TALLOC_FREE(conn);
                return ERROR_DNS_CONNECTION_FAILED;
        }

        talloc_set_destructor(conn, destroy_dns_connection);

        /* Set up the RecvAddr structure with the IP address of
           the receiver (in this example case "123.456.789.1")
           and the specified port number. */

        RecvAddr.sin_family = AF_INET;
        RecvAddr.sin_port = htons( DNS_UDP_PORT );
        RecvAddr.sin_addr.s_addr = ulAddress;

        conn->hType = DNS_UDP;
        memcpy( &conn->RecvAddr, &RecvAddr, sizeof( struct sockaddr_in ) );

        *result = conn;
        return ERROR_DNS_SUCCESS;
}

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

DNS_ERROR dns_open_connection( const char *nameserver, int32 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 *data, size_t len)
{
        size_t total = 0;

        while (total < len) {

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

                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 len = htons(buf->offset);
        DNS_ERROR err;

        err = write_all(conn->s, (uint8 *)&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;

        ret = sendto(conn->s, buf->data, buf->offset, 0,
                     (struct sockaddr *)&conn->RecvAddr,
                     sizeof(conn->RecvAddr));

        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 *data, size_t len)
{
        size_t total = 0;
        fd_set rfds;
        struct timeval tv;

        while (total < len) {
                ssize_t ret;
                int fd_ready;
                
                FD_ZERO( &rfds );
                FD_SET( fd, &rfds );

                /* 10 second timeout */
                tv.tv_sec = 10;
                tv.tv_usec = 0;
                
                fd_ready = select( fd+1, &rfds, NULL, NULL, &tv );
                if ( fd_ready == 0 ) {
                        /* read timeout */
                        return ERROR_DNS_SOCKET_ERROR;
                }

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

        if (!(buf = TALLOC_ZERO_P(mem_ctx, struct dns_buffer))) {
                return ERROR_DNS_NO_MEMORY;
        }

        err = read_all(conn->s, (uint8 *)&len, sizeof(len));
        if (!ERR_DNS_IS_OK(err)) {
                return err;
        }

        buf->size = ntohs(len);

        if (buf->size) {
                if (!(buf->data = TALLOC_ARRAY(buf, uint8, buf->size))) {
                        TALLOC_FREE(buf);
                        return ERROR_DNS_NO_MEMORY;
                }
        } else {
                buf->data = NULL;
        }

        err = read_all(conn->s, buf->data, buf->size);
        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_P(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, 512))) {
                TALLOC_FREE(buf);
                return ERROR_DNS_NO_MEMORY;
        }

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

        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(conn, 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;
}

---