/*
   Unix SMB/Netbios implementation.
   Version 1.9.
   Samba utility functions

   Copyright (C) Andrew Tridgell 1992-1998

   Copyright (C) 2011-2017
   Free Software Foundation, Inc.

   This file is part of the Midnight Commander.

   The Midnight Commander 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 of the License,
   or (at your option) any later version.

   The Midnight Commander 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "includes.h"

const char *unix_error_string (int error_num);

#ifdef WITH_SSL
#include <ssl.h>
#undef Realloc                  /* SSLeay defines this and samba has a function of this name */
extern SSL *ssl;
extern int sslFd;
#endif /* WITH_SSL */

extern int DEBUGLEVEL;

BOOL passive = False;

/* the client file descriptor */
int Client = -1;

/* the last IP received from */
struct in_addr lastip;

/* the last port received from */
int lastport = 0;


int smb_read_error = 0;


/****************************************************************************
determine if a file descriptor is in fact a socket
****************************************************************************/
BOOL
is_a_socket (int fd)
{
    int v;
    unsigned int l;
    l = sizeof (int);
    return (getsockopt (fd, SOL_SOCKET, SO_TYPE, (char *) &v, &l) == 0);
}


enum SOCK_OPT_TYPES
{ OPT_BOOL, OPT_INT, OPT_ON };

static const struct
{
    const char *name;
    int level;
    int option;
    int value;
    int opttype;
} socket_options[] =
{
    {
    "SO_KEEPALIVE", SOL_SOCKET, SO_KEEPALIVE, 0, OPT_BOOL},
    {
    "SO_REUSEADDR", SOL_SOCKET, SO_REUSEADDR, 0, OPT_BOOL},
    {
    "SO_BROADCAST", SOL_SOCKET, SO_BROADCAST, 0, OPT_BOOL},
#ifdef TCP_NODELAY
    {
    "TCP_NODELAY", IPPROTO_TCP, TCP_NODELAY, 0, OPT_BOOL},
#endif
#ifdef IPTOS_LOWDELAY
    {
    "IPTOS_LOWDELAY", IPPROTO_IP, IP_TOS, IPTOS_LOWDELAY, OPT_ON},
#endif
#ifdef IPTOS_THROUGHPUT
    {
    "IPTOS_THROUGHPUT", IPPROTO_IP, IP_TOS, IPTOS_THROUGHPUT, OPT_ON},
#endif
#ifdef SO_SNDBUF
    {
    "SO_SNDBUF", SOL_SOCKET, SO_SNDBUF, 0, OPT_INT},
#endif
#ifdef SO_RCVBUF
    {
    "SO_RCVBUF", SOL_SOCKET, SO_RCVBUF, 0, OPT_INT},
#endif
#ifdef SO_SNDLOWAT
    {
    "SO_SNDLOWAT", SOL_SOCKET, SO_SNDLOWAT, 0, OPT_INT},
#endif
#ifdef SO_RCVLOWAT
    {
    "SO_RCVLOWAT", SOL_SOCKET, SO_RCVLOWAT, 0, OPT_INT},
#endif
#ifdef SO_SNDTIMEO
    {
    "SO_SNDTIMEO", SOL_SOCKET, SO_SNDTIMEO, 0, OPT_INT},
#endif
#ifdef SO_RCVTIMEO
    {
    "SO_RCVTIMEO", SOL_SOCKET, SO_RCVTIMEO, 0, OPT_INT},
#endif
    {
NULL, 0, 0, 0, 0}};



/****************************************************************************
set user socket options
****************************************************************************/
void
set_socket_options (int fd, char *options)
{
    fstring tok;

    while (next_token (&options, tok, " \t,", sizeof (tok)))
    {
        int ret = 0, i;
        int value = 1;
        char *p;
        BOOL got_value = False;

        if ((p = strchr (tok, '=')))
        {
            *p = 0;
            value = atoi (p + 1);
            got_value = True;
        }

        for (i = 0; socket_options[i].name; i++)
            if (strequal (socket_options[i].name, tok))
                break;

        if (!socket_options[i].name)
        {
            DEBUG (0, ("Unknown socket option %s\n", tok));
            continue;
        }

        switch (socket_options[i].opttype)
        {
        case OPT_BOOL:
        case OPT_INT:
            ret = setsockopt (fd, socket_options[i].level,
                              socket_options[i].option, (char *) &value, sizeof (int));
            break;

        case OPT_ON:
            if (got_value)
                DEBUG (0, ("syntax error - %s does not take a value\n", tok));

            {
                int on = socket_options[i].value;
                ret = setsockopt (fd, socket_options[i].level,
                                  socket_options[i].option, (char *) &on, sizeof (int));
            }
            break;
        }

        if (ret != 0)
            DEBUG (0, ("Failed to set socket option %s\n", tok));
    }
}



/****************************************************************************
  close the socket communication
****************************************************************************/
void
close_sockets (void)
{
#ifdef WITH_SSL
    sslutil_disconnect (Client);
#endif /* WITH_SSL */

    close (Client);
    Client = -1;
}



/****************************************************************************
write to a socket
****************************************************************************/
ssize_t
write_socket (int fd, char *buf, size_t len)
{
    ssize_t ret = 0;

    if (passive)
        return (len);
    DEBUG (6, ("write_socket(%d,%d)\n", fd, (int) len));
    ret = write_data (fd, buf, len);

    DEBUG (6, ("write_socket(%d,%d) wrote %d\n", fd, (int) len, (int) ret));
    if (ret <= 0)
        DEBUG (1, ("write_socket: Error writing %d bytes to socket %d: ERRNO = %s\n",
                   (int) len, fd, unix_error_string (errno)));

    return (ret);
}

/****************************************************************************
read from a socket
****************************************************************************/
ssize_t
read_udp_socket (int fd, char *buf, size_t len)
{
    ssize_t ret;
    struct sockaddr_in sock;
    unsigned int socklen;

    socklen = sizeof (sock);
    memset ((char *) &sock, '\0', socklen);
    memset ((char *) &lastip, '\0', sizeof (lastip));
    ret = (ssize_t) recvfrom (fd, buf, len, 0, (struct sockaddr *) &sock, &socklen);
    if (ret <= 0)
    {
        DEBUG (2, ("read socket failed. ERRNO=%s\n", unix_error_string (errno)));
        return (0);
    }

    lastip = sock.sin_addr;
    lastport = ntohs (sock.sin_port);

    DEBUG (10, ("read_udp_socket: lastip %s lastport %d read: %d\n",
                inet_ntoa (lastip), lastport, (int) ret));

    return (ret);
}


/****************************************************************************
read data from a device with a timout in msec.
mincount = if timeout, minimum to read before returning
maxcount = number to be read.
time_out = timeout in milliseconds
****************************************************************************/

ssize_t
read_with_timeout (int fd, char *buf, size_t mincnt, size_t maxcnt, unsigned int time_out)
{
    fd_set fds;
    int selrtn;
    ssize_t readret;
    size_t nread = 0;
    struct timeval timeout;

    /* just checking .... */
    if (maxcnt <= 0)
        return (0);

    smb_read_error = 0;

    /* Blocking read */
    if (time_out <= 0)
    {
        if (mincnt == 0)
            mincnt = maxcnt;

        while (nread < mincnt)
        {
#ifdef WITH_SSL
            if (fd == sslFd)
            {
                readret = SSL_read (ssl, buf + nread, maxcnt - nread);
            }
            else
            {
                readret = read (fd, buf + nread, maxcnt - nread);
            }
#else /* WITH_SSL */
            readret = read (fd, buf + nread, maxcnt - nread);
#endif /* WITH_SSL */

            if (readret == 0)
            {
                DEBUG (5, ("read_with_timeout: blocking read. EOF from client.\n"));
                smb_read_error = READ_EOF;
                return -1;
            }

            if (readret == -1)
            {
                DEBUG (0, ("read_with_timeout: read error = %s.\n", unix_error_string (errno)));
                smb_read_error = READ_ERROR;
                return -1;
            }
            nread += readret;
        }
        return ((ssize_t) nread);
    }

    /* Most difficult - timeout read */
    /* If this is ever called on a disk file and 
       mincnt is greater than the filesize then
       system performance will suffer severely as 
       select always returns true on disk files */

    /* Set initial timeout */
    timeout.tv_sec = (time_t) (time_out / 1000);
    timeout.tv_usec = (long) (1000 * (time_out % 1000));

    for (nread = 0; nread < mincnt;)
    {
        FD_ZERO (&fds);
        FD_SET (fd, &fds);

        selrtn = sys_select (fd + 1, &fds, &timeout);

        /* Check if error */
        if (selrtn == -1)
        {
            /* something is wrong. Maybe the socket is dead? */
            DEBUG (0,
                   ("read_with_timeout: timeout read. select error = %s.\n",
                    unix_error_string (errno)));
            smb_read_error = READ_ERROR;
            return -1;
        }

        /* Did we timeout ? */
        if (selrtn == 0)
        {
            DEBUG (10, ("read_with_timeout: timeout read. select timed out.\n"));
            smb_read_error = READ_TIMEOUT;
            return -1;
        }

#ifdef WITH_SSL
        if (fd == sslFd)
        {
            readret = SSL_read (ssl, buf + nread, maxcnt - nread);
        }
        else
        {
            readret = read (fd, buf + nread, maxcnt - nread);
        }
#else /* WITH_SSL */
        readret = read (fd, buf + nread, maxcnt - nread);
#endif /* WITH_SSL */

        if (readret == 0)
        {
            /* we got EOF on the file descriptor */
            DEBUG (5, ("read_with_timeout: timeout read. EOF from client.\n"));
            smb_read_error = READ_EOF;
            return -1;
        }

        if (readret == -1)
        {
            /* the descriptor is probably dead */
            DEBUG (0,
                   ("read_with_timeout: timeout read. read error = %s.\n",
                    unix_error_string (errno)));
            smb_read_error = READ_ERROR;
            return -1;
        }

        nread += readret;
    }

    /* Return the number we got */
    return ((ssize_t) nread);
}


/****************************************************************************
send a keepalive packet (rfc1002)
****************************************************************************/
BOOL
send_keepalive (int client)
{
    unsigned char buf[4];

    buf[0] = 0x85;
    buf[1] = buf[2] = buf[3] = 0;

    return (write_data (client, (char *) buf, 4) == 4);
}



/****************************************************************************
  read data from the client, reading exactly N bytes. 
****************************************************************************/
ssize_t
read_data (int fd, char *buffer, size_t N)
{
    ssize_t ret;
    size_t total = 0;

    smb_read_error = 0;

    while (total < N)
    {
#ifdef WITH_SSL
        if (fd == sslFd)
        {
            ret = SSL_read (ssl, buffer + total, N - total);
        }
        else
        {
            ret = read (fd, buffer + total, N - total);
        }
#else /* WITH_SSL */
        ret = read (fd, buffer + total, N - total);
#endif /* WITH_SSL */

        if (ret == 0)
        {
            DEBUG (10,
                   ("read_data: read of %d returned 0. Error = %s\n", (int) (N - total),
                    unix_error_string (errno)));
            smb_read_error = READ_EOF;
            return 0;
        }
        if (ret == -1)
        {
            DEBUG (0,
                   ("read_data: read failure for %d. Error = %s\n", (int) (N - total),
                    unix_error_string (errno)));
            smb_read_error = READ_ERROR;
            return -1;
        }
        total += ret;
    }
    return (ssize_t) total;
}


/****************************************************************************
  write data to a fd 
****************************************************************************/
ssize_t
write_data (int fd, char *buffer, size_t N)
{
    size_t total = 0;
    ssize_t ret;

    while (total < N)
    {
#ifdef WITH_SSL
        if (fd == sslFd)
        {
            ret = SSL_write (ssl, buffer + total, N - total);
        }
        else
        {
            ret = write (fd, buffer + total, N - total);
        }
#else /* WITH_SSL */
        ret = write (fd, buffer + total, N - total);
#endif /* WITH_SSL */

        if (ret == -1)
        {
            DEBUG (1, ("write_data: write failure. Error = %s\n", unix_error_string (errno)));
            return -1;
        }
        if (ret == 0)
            return total;

        total += ret;
    }
    return (ssize_t) total;
}



/****************************************************************************
read 4 bytes of a smb packet and return the smb length of the packet
store the result in the buffer
This version of the function will return a length of zero on receiving
a keepalive packet.
timeout is in milliseconds.
****************************************************************************/
static ssize_t
read_smb_length_return_keepalive (int fd, char *inbuf, unsigned int timeout)
{
    ssize_t len = 0;
    int msg_type;
    BOOL ok = False;

    while (!ok)
    {
        if (timeout > 0)
            ok = (read_with_timeout (fd, inbuf, 4, 4, timeout) == 4);
        else
            ok = (read_data (fd, inbuf, 4) == 4);

        if (!ok)
            return (-1);

        len = smb_len (inbuf);
        msg_type = CVAL (inbuf, 0);

        if (msg_type == 0x85)
            DEBUG (5, ("Got keepalive packet\n"));
    }

    DEBUG (10, ("got smb length of %d\n", (int) len));

    return (len);
}

#if 0
/****************************************************************************
read 4 bytes of a smb packet and return the smb length of the packet
store the result in the buffer. This version of the function will
never return a session keepalive (length of zero).
timeout is in milliseconds.
****************************************************************************/
ssize_t
read_smb_length (int fd, char *inbuf, unsigned int timeout)
{
    ssize_t len;

    for (;;)
    {
        len = read_smb_length_return_keepalive (fd, inbuf, timeout);

        if (len < 0)
            return len;

        /* Ignore session keepalives. */
        if (CVAL (inbuf, 0) != 0x85)
            break;
    }

    DEBUG (10, ("read_smb_length: got smb length of %d\n", len));

    return len;
}
#endif /* 0 */
/****************************************************************************
  read an smb from a fd. Note that the buffer *MUST* be of size
  BUFFER_SIZE+SAFETY_MARGIN.
  The timeout is in milliseconds. 
  This function will return on a
  receipt of a session keepalive packet.
****************************************************************************/
BOOL
receive_smb (int fd, char *buffer, unsigned int timeout)
{
    ssize_t len, ret;

    smb_read_error = 0;

    memset (buffer, '\0', smb_size + 100);

    len = read_smb_length_return_keepalive (fd, buffer, timeout);
    if (len < 0)
    {
        DEBUG (10, ("receive_smb: length < 0!\n"));
        return (False);
    }

    if (len > BUFFER_SIZE)
    {
        DEBUG (0, ("Invalid packet length! (%d bytes).\n", (int) len));
        if (len > BUFFER_SIZE + (SAFETY_MARGIN / 2))
        {
            exit (1);
        }
    }

    if (len > 0)
    {
        ret = read_data (fd, buffer + 4, len);
        if (ret != len)
        {
            smb_read_error = READ_ERROR;
            return False;
        }
    }
    return (True);
}

/****************************************************************************
  read an smb from a fd ignoring all keepalive packets. Note that the buffer 
  *MUST* be of size BUFFER_SIZE+SAFETY_MARGIN.
  The timeout is in milliseconds

  This is exactly the same as receive_smb except that it never returns
  a session keepalive packet (just as receive_smb used to do).
  receive_smb was changed to return keepalives as the oplock processing means this call
  should never go into a blocking read.
****************************************************************************/

BOOL
client_receive_smb (int fd, char *buffer, unsigned int timeout)
{
    BOOL ret;

    for (;;)
    {
        ret = receive_smb (fd, buffer, timeout);

        if (!ret)
        {
            DEBUG (10, ("client_receive_smb failed\n"));
            show_msg (buffer);
            return ret;
        }

        /* Ignore session keepalive packets. */
        if (CVAL (buffer, 0) != 0x85)
            break;
    }
    show_msg (buffer);
    return ret;
}

/****************************************************************************
  send an null session message to a fd
****************************************************************************/
#if 0
BOOL
send_null_session_msg (int fd)
{
    ssize_t ret;
    uint32 blank = 0;
    size_t len = 4;
    size_t nwritten = 0;
    char *buffer = (char *) &blank;

    while (nwritten < len)
    {
        ret = write_socket (fd, buffer + nwritten, len - nwritten);
        if (ret <= 0)
        {
            DEBUG (0,
                   ("send_null_session_msg: Error writing %d bytes to client. %d. Exiting\n",
                    (int) len, (int) ret));
            close_sockets ();
            exit (1);
        }
        nwritten += ret;
    }

    DEBUG (10, ("send_null_session_msg: sent 4 null bytes to client.\n"));
    return True;
}

/****************************************************************************
  send an smb to a fd 
****************************************************************************/
BOOL
send_smb (int fd, char *buffer)
{
    size_t len;
    size_t nwritten = 0;
    ssize_t ret;
    len = smb_len (buffer) + 4;

    while (nwritten < len)
    {
        ret = write_socket (fd, buffer + nwritten, len - nwritten);
        if (ret <= 0)
        {
            DEBUG (0, ("Error writing %d bytes to client. %d. Exiting\n", (int) len, (int) ret));
            close_sockets ();
            exit (1);
        }
        nwritten += ret;
    }

    return True;
}



/****************************************************************************
send a single packet to a port on another machine
****************************************************************************/
BOOL
send_one_packet (char *buf, int len, struct in_addr ip, int port, int type)
{
    BOOL ret;
    int out_fd;
    struct sockaddr_in sock_out;

    if (passive)
        return (True);

    /* create a socket to write to */
    out_fd = socket (AF_INET, type, 0);
    if (out_fd == -1)
    {
        DEBUG (0, ("socket failed"));
        return False;
    }

    /* set the address and port */
    memset ((char *) &sock_out, '\0', sizeof (sock_out));
    putip ((char *) &sock_out.sin_addr, (char *) &ip);
    sock_out.sin_port = htons (port);
    sock_out.sin_family = AF_INET;

    if (DEBUGLEVEL > 0)
        DEBUG (3, ("sending a packet of len %d to (%s) on port %d of type %s\n",
                   len, inet_ntoa (ip), port, type == SOCK_DGRAM ? "DGRAM" : "STREAM"));

    /* send it */
    ret = (sendto (out_fd, buf, len, 0, (struct sockaddr *) &sock_out, sizeof (sock_out)) >= 0);

    if (!ret)
        DEBUG (0, ("Packet send to %s(%d) failed ERRNO=%s\n",
                   inet_ntoa (ip), port, unix_error_string (errno)));

    close (out_fd);
    return (ret);
}
#endif /* 0 */

/****************************************************************************
open a socket of the specified type, port and address for incoming data
****************************************************************************/
int
open_socket_in (int type, int port, int dlevel, uint32 socket_addr, BOOL rebind)
{
    struct hostent *hp;
    struct sockaddr_in sock;
    pstring host_name;
    int res;

    /* get my host name */
    if (gethostname (host_name, MAXHOSTNAMELEN) == -1)
    {
        DEBUG (0, ("gethostname failed\n"));
        return -1;
    }

    /* get host info */
    if ((hp = Get_Hostbyname (host_name)) == 0)
    {
        DEBUG (0, ("Get_Hostbyname: Unknown host %s\n", host_name));
        return -1;
    }

    memset ((char *) &sock, '\0', sizeof (sock));
    memcpy ((char *) &sock.sin_addr, (char *) hp->h_addr, hp->h_length);

#ifdef HAVE_SOCK_SIN_LEN
    sock.sin_len = sizeof (sock);
#endif
    sock.sin_port = htons (port);
    sock.sin_family = hp->h_addrtype;
    sock.sin_addr.s_addr = socket_addr;
    res = socket (hp->h_addrtype, type, 0);
    if (res == -1)
    {
        DEBUG (0, ("socket failed\n"));
        return -1;
    }

    {
        int val = 1;
        if (rebind)
            val = 1;
        else
            val = 0;
        setsockopt (res, SOL_SOCKET, SO_REUSEADDR, (char *) &val, sizeof (val));
    }

    /* now we've got a socket - we need to bind it */
    if (bind (res, (struct sockaddr *) &sock, sizeof (sock)) < 0)
    {
        if (port)
        {
            if (port == SMB_PORT || port == NMB_PORT)
                DEBUG (dlevel, ("bind failed on port %d socket_addr=%s (%s)\n",
                                port, inet_ntoa (sock.sin_addr), unix_error_string (errno)));
            close (res);

            if (dlevel > 0 && port < 1000)
                port = 7999;

            if (port >= 1000 && port < 9000)
                return (open_socket_in (type, port + 1, dlevel, socket_addr, rebind));
        }

        return (-1);
    }
    DEBUG (3, ("bind succeeded on port %d\n", port));

    return res;
}


/****************************************************************************
  create an outgoing socket. timeout is in milliseconds.
  **************************************************************************/
int
open_socket_out (int type, struct in_addr *addr, int port, int timeout)
{
    struct sockaddr_in sock_out;
    int res, ret;
    int connect_loop = 250;     /* 250 milliseconds */
    int loops = (timeout) / connect_loop;

    /* create a socket to write to */
    res = socket (PF_INET, type, 0);
    if (res == -1)
    {
        DEBUG (0, ("socket error\n"));
        return -1;
    }

    if (type != SOCK_STREAM)
        return (res);

    memset ((char *) &sock_out, '\0', sizeof (sock_out));
    putip ((char *) &sock_out.sin_addr, (char *) addr);

    sock_out.sin_port = htons (port);
    sock_out.sin_family = PF_INET;

    /* set it non-blocking */
    set_blocking (res, False);

    DEBUG (3, ("Connecting to %s at port %d\n", inet_ntoa (*addr), port));

    /* and connect it to the destination */
  connect_again:
    ret = connect (res, (struct sockaddr *) &sock_out, sizeof (sock_out));

    /* Some systems return EAGAIN when they mean EINPROGRESS */
    if (ret < 0 && (errno == EINPROGRESS || errno == EALREADY || errno == EAGAIN) && loops--)
    {
        msleep (connect_loop);
        goto connect_again;
    }

    if (ret < 0 && (errno == EINPROGRESS || errno == EALREADY || errno == EAGAIN))
    {
        DEBUG (1, ("timeout connecting to %s:%d\n", inet_ntoa (*addr), port));
        close (res);
        return -1;
    }

#ifdef EISCONN
    if (ret < 0 && errno == EISCONN)
    {
        errno = 0;
        ret = 0;
    }
#endif

    if (ret < 0)
    {
        DEBUG (1, ("error connecting to %s:%d (%s)\n",
                   inet_ntoa (*addr), port, unix_error_string (errno)));
        close (res);
        return -1;
    }

    /* set it blocking again */
    set_blocking (res, True);

    return res;
}


/*******************************************************************
 Reset the 'done' variables so after a client process is created
 from a fork call these calls will be re-done. This should be
 expanded if more variables need reseting.
 ******************************************************************/

static BOOL global_client_name_done = False;
static BOOL global_client_addr_done = False;

/*******************************************************************
 return the DNS name of the client 
 ******************************************************************/
char *
client_name (int fd)
{
    struct sockaddr sa;
    struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
    unsigned int length = sizeof (sa);
    static pstring name_buf;
    struct hostent *hp;
    static int last_fd = -1;

    if (global_client_name_done && last_fd == fd)
        return name_buf;

    last_fd = fd;
    global_client_name_done = False;

    pstrcpy (name_buf, "UNKNOWN");

    if (fd == -1)
    {
        return name_buf;
    }

    if (getpeername (fd, &sa, &length) < 0)
    {
        DEBUG (0, ("getpeername failed. Error was %s\n", unix_error_string (errno)));
        return name_buf;
    }

    /* Look up the remote host name. */
    if ((hp = gethostbyaddr ((char *) &sockin->sin_addr, sizeof (sockin->sin_addr), AF_INET)) == 0)
    {
        DEBUG (1, ("Gethostbyaddr failed for %s\n", client_addr (fd)));
        StrnCpy (name_buf, client_addr (fd), sizeof (name_buf) - 1);
    }
    else
    {
        StrnCpy (name_buf, (char *) hp->h_name, sizeof (name_buf) - 1);
        if (!matchname (name_buf, sockin->sin_addr))
        {
            DEBUG (0, ("Matchname failed on %s %s\n", name_buf, client_addr (fd)));
            pstrcpy (name_buf, "UNKNOWN");
        }
    }
    global_client_name_done = True;
    return name_buf;
}

/*******************************************************************
 return the IP addr of the client as a string 
 ******************************************************************/
char *
client_addr (int fd)
{
    struct sockaddr sa;
    struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
    unsigned int length = sizeof (sa);
    static fstring addr_buf;
    static int last_fd = -1;

    if (global_client_addr_done && fd == last_fd)
        return addr_buf;

    last_fd = fd;
    global_client_addr_done = False;

    fstrcpy (addr_buf, "0.0.0.0");

    if (fd == -1)
    {
        return addr_buf;
    }

    if (getpeername (fd, &sa, &length) < 0)
    {
        DEBUG (0, ("getpeername failed. Error was %s\n", unix_error_string (errno)));
        return addr_buf;
    }

    fstrcpy (addr_buf, (char *) inet_ntoa (sockin->sin_addr));

    global_client_addr_done = True;
    return addr_buf;
}
