NAME

       endservent,  getservbyname,  getservbyport,  getservent,  setservent  -  network  services
       database functions

SYNOPSIS

       #include <netdb.h>

       void endservent(void);
       struct servent *getservbyname(const char *name, const char *proto);
       struct servent *getservbyport(int port, const char *proto);
       struct servent *getservent(void);
       void setservent(int stayopen);

DESCRIPTION

       These functions shall retrieve information about network services.   This  information  is
       considered  to  be stored in a database that can be accessed sequentially or randomly. The
       implementation of this database is unspecified.

       The setservent() function shall open a connection to the database, and set the next  entry
       to  the  first  entry. If the stayopen argument is non-zero, the net database shall not be
       closed after each call to  the  getservent()  function  (either  directly,  or  indirectly
       through  one  of  the  other getserv*() functions), and the implementation may maintain an
       open file descriptor for the database.

       The getservent() function shall read the next entry of the database, opening and closing a
       connection to the database as necessary.

       The  getservbyname()  function  shall  search the database from the beginning and find the
       first entry for which the service name specified by name matches the s_name member and the
       protocol  name  specified  by  proto  matches  the  s_proto  member, opening and closing a
       connection to the database as necessary. If proto is a null  pointer,  any  value  of  the
       s_proto member shall be matched.

       The  getservbyport()  function  shall  search the database from the beginning and find the
       first entry for which the port specified  by  port  matches  the  s_port  member  and  the
       protocol  name  specified  by  proto  matches  the  s_proto  member, opening and closing a
       connection to the database as necessary. If proto is a null  pointer,  any  value  of  the
       s_proto member shall be matched. The port argument shall be in network byte order.

       The  getservbyname(),  getservbyport(),  and  getservent()  functions  shall each return a
       pointer to a servent structure, the members of which shall contain the fields of an  entry
       in the network services database.

       The endservent() function shall close the database, releasing any open file descriptor.

       These  functions need not be reentrant. A function that is not required to be reentrant is
       not required to be thread-safe.

RETURN VALUE

       Upon successful completion, getservbyname(), getservbyport(), and  getservent()  return  a
       pointer to a servent structure if the requested entry was found, and a null pointer if the
       end of the database was reached or the requested entry was not found.  Otherwise,  a  null
       pointer is returned.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The  port  argument  of getservbyport() need not be compatible with the port values of all
       address families.

       The getservbyname(), getservbyport(), and getservent() functions may  return  pointers  to
       static data, which may be overwritten by subsequent calls to any of these functions.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       endhostent()  ,  endprotoent()  ,  htonl()  , inet_addr() , the Base Definitions volume of
       IEEE Std 1003.1-2001, <netdb.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .