path: root/source3/lib/util_sock.c

/* 
   Unix SMB/CIFS implementation.
   Samba utility functions
   Copyright (C) Andrew Tridgell 1992-1998
   Copyright (C) Tim Potter      2000-2001
   
   This program 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 of the License, or
   (at your option) any later version.
   
   This program 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

/* 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,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};

typedef struct smb_socket_option {
	const char *name;
	int level;
	int option;
	int value;
	int opttype;
} smb_socket_option;

static const smb_socket_option 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_REUSEPORT
  {"SO_REUSEPORT",      SOL_SOCKET,    SO_REUSEPORT,    0,                 OPT_BOOL},
#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}};

/****************************************************************************
 Print socket options.
****************************************************************************/

static void print_socket_options(int s)
{
	int value, vlen = 4;
	const smb_socket_option *p = &socket_options[0];

	/* wrapped in if statement to prevent streams leak in SCO Openserver 5.0 */
	/* reported on samba-technical  --jerry */
	if ( DEBUGLEVEL >= 5 ) {
	for (; p->name != NULL; p++) {
		if (getsockopt(s, p->level, p->option, (void *)&value, &vlen) == -1) {
			DEBUG(5,("Could not test socket option %s.\n", p->name));
		} else {
			DEBUG(5,("socket option %s = %d\n",p->name,value));
			}
		}
	}
 }

/****************************************************************************
 Set user socket options.
****************************************************************************/

void set_socket_options(int fd, const 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_m(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 (Error %s)\n",tok, strerror(errno) ));
	}

	print_socket_options(fd);
}

/****************************************************************************
 Read from a socket.
****************************************************************************/

ssize_t read_udp_socket(int fd,char *buf,size_t len)
{
	ssize_t ret;
	struct sockaddr_in sock;
	socklen_t socklen = sizeof(sock);

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

	return(ret);
}

/****************************************************************************
 Read data from a socket 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_socket_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) {
			readret = sys_read(fd, buf + nread, maxcnt - nread);
			
			if (readret == 0) {
				DEBUG(5,("read_socket_with_timeout: blocking read. EOF from client.\n"));
				smb_read_error = READ_EOF;
				return -1;
			}
			
			if (readret == -1) {
				DEBUG(0,("read_socket_with_timeout: read error = %s.\n", strerror(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 then 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_intr(fd+1,&fds,NULL,NULL,&timeout);
		
		/* Check if error */
		if (selrtn == -1) {
			/* something is wrong. Maybe the socket is dead? */
			DEBUG(0,("read_socket_with_timeout: timeout read. select error = %s.\n", strerror(errno) ));
			smb_read_error = READ_ERROR;
			return -1;
		}
		
		/* Did we timeout ? */
		if (selrtn == 0) {
			DEBUG(10,("read_socket_with_timeout: timeout read. select timed out.\n"));
			smb_read_error = READ_TIMEOUT;
			return -1;
		}
		
		readret = sys_read(fd, buf+nread, maxcnt-nread);
		
		if (readret == 0) {
			/* we got EOF on the file descriptor */
			DEBUG(5,("read_socket_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_socket_with_timeout: timeout read. read error = %s.\n", strerror(errno) ));
			smb_read_error = READ_ERROR;
			return -1;
		}
		
		nread += readret;
	}
	
	/* Return the number we got */
	return (ssize_t)nread;
}

/****************************************************************************
  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) {
		ret = sys_read(fd,buffer + total,N - total);

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

/****************************************************************************
 Read data from a socket, reading exactly N bytes. 
****************************************************************************/

static ssize_t read_socket_data(int fd,char *buffer,size_t N)
{
	ssize_t ret;
	size_t total=0;  
 
	smb_read_error = 0;

	while (total < N) {
		ret = sys_read(fd,buffer + total,N - total);

		if (ret == 0) {
			DEBUG(10,("read_socket_data: recv of %d returned 0. Error = %s\n", (int)(N - total), strerror(errno) ));
			smb_read_error = READ_EOF;
			return 0;
		}

		if (ret == -1) {
			DEBUG(0,("read_socket_data: recv failure for %d. Error = %s\n", (int)(N - total), strerror(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) {
		ret = sys_write(fd,buffer + total,N - total);

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

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

/****************************************************************************
 Write data to a socket - use send rather than write.
****************************************************************************/

static ssize_t write_socket_data(int fd,char *buffer,size_t N)
{
	size_t total=0;
	ssize_t ret;

	while (total < N) {
		ret = sys_send(fd,buffer + total,N - total,0);

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

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

/****************************************************************************
write to a socket
****************************************************************************/

ssize_t write_socket(int fd,char *buf,size_t len)
{
	ssize_t ret=0;

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

	return(ret);
}

/****************************************************************************
send a keepalive packet (rfc1002)
****************************************************************************/

BOOL send_keepalive(int client)
{
	unsigned char buf[4];

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

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


/****************************************************************************
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_socket_with_timeout(fd,inbuf,4,4,timeout) == 4);
		else 
			ok = (read_socket_data(fd,inbuf,4) == 4);

		if (!ok)
			return(-1);

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

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

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

	return(len);
}

/****************************************************************************
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) != SMBkeepalive)
			break;
	}

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

	return len;
}

/****************************************************************************
  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"));

		/*
		 * Correct fix. smb_read_error may have already been
		 * set. Only set it here if not already set. Global
		 * variables still suck :-). JRA.
		 */

		if (smb_read_error == 0)
			smb_read_error = READ_ERROR;
		return False;
	}

	/*
	 * A WRITEX with CAP_LARGE_WRITEX can be 64k worth of data plus 65 bytes
	 * of header. Don't print the error if this fits.... JRA.
	 */

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

			/*
			 * Correct fix. smb_read_error may have already been
			 * set. Only set it here if not already set. Global
			 * variables still suck :-). JRA.
			 */

			if (smb_read_error == 0)
				smb_read_error = READ_ERROR;
			return False;
		}
	}

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

	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. (%s)\n",
				(int)len,(int)ret, strerror(errno) ));
			return False;
		}
		nwritten += ret;
	}

	return True;
}

/****************************************************************************
 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 sockaddr_in sock;
	int res;

	memset( (char *)&sock, '\0', sizeof(sock) );

#ifdef HAVE_SOCK_SIN_LEN
	sock.sin_len         = sizeof(sock);
#endif
	sock.sin_port        = htons( port );
	sock.sin_family      = AF_INET;
	sock.sin_addr.s_addr = socket_addr;

	res = socket( AF_INET, type, 0 );
	if( res == -1 ) {
		if( DEBUGLVL(0) ) {
			dbgtext( "open_socket_in(): socket() call failed: " );
			dbgtext( "%s\n", strerror( errno ) );
		}
		return -1;
	}

	/* This block sets/clears the SO_REUSEADDR and possibly SO_REUSEPORT. */
	{
		int val = rebind ? 1 : 0;
		if( setsockopt(res,SOL_SOCKET,SO_REUSEADDR,(char *)&val,sizeof(val)) == -1 ) {
			if( DEBUGLVL( dlevel ) ) {
				dbgtext( "open_socket_in(): setsockopt: " );
				dbgtext( "SO_REUSEADDR = %s ", val?"True":"False" );
				dbgtext( "on port %d failed ", port );
				dbgtext( "with error = %s\n", strerror(errno) );
			}
		}
#ifdef SO_REUSEPORT
		if( setsockopt(res,SOL_SOCKET,SO_REUSEPORT,(char *)&val,sizeof(val)) == -1 ) {
			if( DEBUGLVL( dlevel ) ) {
				dbgtext( "open_socket_in(): setsockopt: ");
				dbgtext( "SO_REUSEPORT = %s ", val?"True":"False" );
				dbgtext( "on port %d failed ", port );
				dbgtext( "with error = %s\n", strerror(errno) );
			}
		}
#endif /* SO_REUSEPORT */
	}

	/* now we've got a socket - we need to bind it */
	if( bind( res, (struct sockaddr *)&sock, sizeof(sock) ) == -1 ) {
		if( DEBUGLVL(dlevel) && (port == SMB_PORT1 || port == SMB_PORT2 || port == NMB_PORT) ) {
			dbgtext( "bind failed on port %d ", port );
			dbgtext( "socket_addr = %s.\n", inet_ntoa( sock.sin_addr ) );
			dbgtext( "Error = %s\n", strerror(errno) );
		}
		close( res ); 
		return( -1 ); 
	}

	DEBUG( 10, ( "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 = 10;
  int increment = 10;

  /* 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) && (connect_loop < timeout) ) {
    msleep(connect_loop);
    connect_loop += increment;
    if (increment < 250) {
	    /* After 8 rounds we end up at a max of 255 msec */
	    increment *= 1.5;
    }
    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(2,("error connecting to %s:%d (%s)\n",
	     inet_ntoa(*addr),port,strerror(errno)));
    close(res);
    return -1;
  }

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

  return res;
}

/*
  open a connected UDP socket to host on port
*/
int open_udp_socket(const char *host, int port)
{
	int type = SOCK_DGRAM;
	struct sockaddr_in sock_out;
	int res;
	struct in_addr *addr;

	addr = interpret_addr2(host);

	res = socket(PF_INET, type, 0);
	if (res == -1) {
		return -1;
	}

	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;

	if (connect(res,(struct sockaddr *)&sock_out,sizeof(sock_out))) {
		close(res);
		return -1;
	}

	return res;
}


/* the following 3 client_*() functions are nasty ways of allowing
   some generic functions to get info that really should be hidden in
   particular modules */
static int client_fd = -1;

void client_setfd(int fd)
{
	client_fd = fd;
}

char *client_name(void)
{
	return get_socket_name(client_fd,False);
}

char *client_addr(void)
{
	return get_socket_addr(client_fd);
}

struct in_addr *client_inaddr(struct sockaddr *sa)
{
	struct sockaddr_in *sockin = (struct sockaddr_in *) (sa);
	int     length = sizeof(*sa);
	
	if (getpeername(client_fd, sa, &length) < 0) {
		DEBUG(0,("getpeername failed. Error was %s\n", strerror(errno) ));
		return NULL;
	}
	
	return &sockin->sin_addr;
}

/*******************************************************************
 matchname - determine if host name matches IP address. Used to
 confirm a hostname lookup to prevent spoof attacks
 ******************************************************************/
static BOOL matchname(char *remotehost,struct in_addr  addr)
{
	struct hostent *hp;
	int     i;
	
	if ((hp = sys_gethostbyname(remotehost)) == 0) {
		DEBUG(0,("sys_gethostbyname(%s): lookup failure.\n", remotehost));
		return False;
	} 

	/*
	 * Make sure that gethostbyname() returns the "correct" host name.
	 * Unfortunately, gethostbyname("localhost") sometimes yields
	 * "localhost.domain". Since the latter host name comes from the
	 * local DNS, we just have to trust it (all bets are off if the local
	 * DNS is perverted). We always check the address list, though.
	 */
	
	if (strcasecmp(remotehost, hp->h_name)
	    && strcasecmp(remotehost, "localhost")) {
		DEBUG(0,("host name/name mismatch: %s != %s\n",
			 remotehost, hp->h_name));
		return False;
	}
	
	/* Look up the host address in the address list we just got. */
	for (i = 0; hp->h_addr_list[i]; i++) {
		if (memcmp(hp->h_addr_list[i], (char *) & addr, sizeof(addr)) == 0)
			return True;
	}
	
	/*
	 * The host name does not map to the original host address. Perhaps
	 * someone has compromised a name server. More likely someone botched
	 * it, but that could be dangerous, too.
	 */
	
	DEBUG(0,("host name/address mismatch: %s != %s\n",
		 inet_ntoa(addr), hp->h_name));
	return False;
}

 
/*******************************************************************
 return the DNS name of the remote end of a socket
 ******************************************************************/
char *get_socket_name(int fd, BOOL force_lookup)
{
	static pstring name_buf;
	static fstring addr_buf;
	struct hostent *hp;
	struct in_addr addr;
	char *p;

	/* reverse lookups can be *very* expensive, and in many
	   situations won't work because many networks don't link dhcp
	   with dns. To avoid the delay we avoid the lookup if
	   possible */
	if (!lp_hostname_lookups() && (force_lookup == False)) {
		return get_socket_addr(fd);
	}
	
	p = get_socket_addr(fd);

	/* it might be the same as the last one - save some DNS work */
	if (strcmp(p, addr_buf) == 0) return name_buf;

	pstrcpy(name_buf,"UNKNOWN");
	if (fd == -1) return name_buf;

	fstrcpy(addr_buf, p);

	addr = *interpret_addr2(p);
	
	/* Look up the remote host name. */
	if ((hp = gethostbyaddr((char *)&addr.s_addr, sizeof(addr.s_addr), AF_INET)) == 0) {
		DEBUG(1,("Gethostbyaddr failed for %s\n",p));
		pstrcpy(name_buf, p);
	} else {
		pstrcpy(name_buf,(char *)hp->h_name);
		if (!matchname(name_buf, addr)) {
			DEBUG(0,("Matchname failed on %s %s\n",name_buf,p));
			pstrcpy(name_buf,"UNKNOWN");
		}
	}

	alpha_strcpy(name_buf, name_buf, "_-.", sizeof(name_buf));
	if (strstr(name_buf,"..")) {
		pstrcpy(name_buf, "UNKNOWN");
	}

	return name_buf;
}

/*******************************************************************
 return the IP addr of the remote end of a socket as a string 
 ******************************************************************/
char *get_socket_addr(int fd)
{
	struct sockaddr sa;
	struct sockaddr_in *sockin = (struct sockaddr_in *) (&sa);
	int     length = sizeof(sa);
	static fstring addr_buf;

	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", strerror(errno) ));
		return addr_buf;
	}
	
	fstrcpy(addr_buf,(char *)inet_ntoa(sockin->sin_addr));
	
	return addr_buf;
}


/*******************************************************************
 Create protected unix domain socket.

 Some unixes cannot set permissions on a ux-dom-sock, so we
 have to make sure that the directory contains the protection
 permissions instead.
 ******************************************************************/

int create_pipe_sock(const char *socket_dir,
		     const char *socket_name,
		     mode_t dir_perms)
{
#ifdef HAVE_UNIXSOCKET
	struct sockaddr_un sunaddr;
	struct stat st;
	int sock;
	mode_t old_umask;
	pstring path;
        
	old_umask = umask(0);
        
	/* Create the socket directory or reuse the existing one */
        
	if (lstat(socket_dir, &st) == -1) {
		if (errno == ENOENT) {
			/* Create directory */
			if (mkdir(socket_dir, dir_perms) == -1) {
				DEBUG(0, ("error creating socket directory "
					"%s: %s\n", socket_dir, 
					strerror(errno)));
				goto out_umask;
			}
		} else {
			DEBUG(0, ("lstat failed on socket directory %s: %s\n",
				socket_dir, strerror(errno)));
			goto out_umask;
		}
	} else {
		/* Check ownership and permission on existing directory */
		if (!S_ISDIR(st.st_mode)) {
			DEBUG(0, ("socket directory %s isn't a directory\n",
				socket_dir));
			goto out_umask;
		}
		if ((st.st_uid != sec_initial_uid()) || 
				((st.st_mode & 0777) != dir_perms)) {
			DEBUG(0, ("invalid permissions on socket directory "
				"%s\n", socket_dir));
			goto out_umask;
		}
	}
        
	/* Create the socket file */
        
	sock = socket(AF_UNIX, SOCK_STREAM, 0);
        
	if (sock == -1) {
		perror("socket");
                goto out_umask;
	}
        
	snprintf(path, sizeof(path), "%s/%s", socket_dir, socket_name);
        
	unlink(path);
	memset(&sunaddr, 0, sizeof(sunaddr));
	sunaddr.sun_family = AF_UNIX;
	safe_strcpy(sunaddr.sun_path, path, sizeof(sunaddr.sun_path)-1);
        
	if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1) {
		DEBUG(0, ("bind failed on pipe socket %s: %s\n", path,
			strerror(errno)));
		goto out_close;
	}
        
	if (listen(sock, 5) == -1) {
		DEBUG(0, ("listen failed on pipe socket %s: %s\n", path,
			strerror(errno)));
		goto out_close;
	}
        
	umask(old_umask);
	return sock;

out_close:
	close(sock);

out_umask:
	umask(old_umask);
	return -1;

#else
        DEBUG(0, ("create_pipe_sock: No Unix sockets on this system\n"));
        return -1;
#endif /* HAVE_UNIXSOCKET */
}