DragonFly On-Line Manual Pages

GETSERVENT(3)         DragonFly Library Functions Manual         GETSERVENT(3)

NAME
     getservent, getservent_r, getservbyport, getservbyport_r, getservbyname,
     getservbyname_r, setservent, endservent - get service entry

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <netdb.h>

     struct servent *
     getservent(void);

     int
     getservent_r(struct servent *, char *, size_t, struct servent **);

     struct servent *
     getservbyname(const char *name, const char *proto);

     int
     getservbyname_r(const char *, const char *, struct servent *, char *,
         size_t, struct servent **);

     struct servent *
     getservbyport(int port, const char *proto);

     int
     getservbyport_r(int, const char *, struct servent *, char *, size_t,
         struct servent **);

     void
     setservent(int stayopen);

     void
     endservent(void);

DESCRIPTION
     The getservent(), getservbyname(), and getservbyport() functions each
     return a pointer to an object with the following structure containing the
     broken-out fields of a line in the network services data base,
     /etc/services.

           struct  servent {
                   char    *s_name;        /* official name of service */
                   char    **s_aliases;    /* alias list */
                   int     s_port;         /* port service resides at */
                   char    *s_proto;       /* protocol to use */
           };

     The members of this structure are:

     s_name     The official name of the service.

     s_aliases  A zero terminated list of alternate names for the service.

     s_port     The port number at which the service resides.  Port numbers
                are returned in network byte order.

     s_proto    The name of the protocol to use when contacting the service.

     The getservent() function reads the next line of the file, opening the
     file if necessary.

     The setservent() function opens and rewinds the file.  If the stayopen
     flag is non-zero, the net data base will not be closed after each call to
     getservbyname() or getservbyport().

     The endservent() function closes the file.

     The getservbyname() and getservbyport() functions sequentially search
     from the beginning of the file until a matching protocol name or port
     number (which must be specified in network byte order) is found, or until
     EOF is encountered.  If a protocol name is also supplied (non- NULL),
     searches must also match the protocol.

     The getservent_r(), getservbyport_r(), and getservbyname_r() functions
     are reentrant versions of the above functions that take a pointer to a
     servent structure which is used to store state information.  The
     structure must be zero-filled before it is used and should be considered
     opaque for the sake of portability.  These functions also take a pointer
     to another servent structure which is used to store the results of the
     database lookup.

RETURN VALUES
     The getservent(), getservbyport(), and getservbyname() functions return a
     pointer to a servent structure on success or a null pointer if end-of-
     file is reached or an error occurs.

     The getservent_r(), getservbyport_r(), and getservbyname_r() functions
     return 0 on success or -1 if end-of-file is reached or an error occurs.

FILES
     /etc/services

SEE ALSO
     getprotoent(3), services(5)

STANDARDS
     The getservent(), getservbyport(), getservbyname(), setservent(), and
     endservent() functions conform to IEEE Std 1003.1-2004 ("POSIX.1").

     The getservent_r(), getservbyport_r(), and getservbyname_r() functions
     are not currently standardized.

HISTORY
     The getservent(), getservbyport(), getservbyname(), setservent(), and
     endservent() functions appeared in 4.2BSD.

     The getservent_r(), getservbyport_r(), and getservbyname_r() functions
     appeared in DragonFly 2.1.

BUGS
     These functions use a thread-specific data storage; if the data is needed
     for future use, it should be copied before any subsequent calls overwrite
     it.  Expecting port numbers to fit in a 32 bit quantity is probably
     naive.

DragonFly 5.5-DEVELOPMENT         May 4, 2019        DragonFly 5.5-DEVELOPMENT