bionic (3) endservent.3posix.gz

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PROLOG
       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.


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 a value
       obtained by converting a uint16_t in network byte order to int.

       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 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.

       The  application  shall  not modify the structure to which the return value points, nor any storage areas
       pointed to by pointers within the structure. The returned pointer, and  pointers  within  the  structure,
       might  be  invalidated or the structure or the storage areas might be overwritten by a subsequent call to
       getservbyname(), getservbyport(), or getservent().


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.


RATIONALE
       None.


FUTURE DIRECTIONS
       None.


SEE ALSO
       endhostent(), endprotoent(), htonl(), inet_addr()

       The Base Definitions volume of POSIX.1‐2008, <netdb.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers,  Inc
       and  The  Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .