getservent(3) - NetBSD Manual Pages

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GETSERVENT(3)           NetBSD Library Functions Manual          GETSERVENT(3)


NAME

     getservent, getservbyport, getservbyname, setservent, endservent -- get
     service entry


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <netdb.h>

     struct servent *
     getservent();

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

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

     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 NULL terminated list of alternative names for the service.

     s_port     The port number at which the service resides.  Port numbers
                must be given and 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 is found, or until EOF is encountered.  If a protocol name is also
     supplied (non-NULL), searches must also match the protocol.


FILES

     /etc/services
     /var/db/services.cdb


RETURN VALUES

     Null pointer is returned on EOF or error.


SEE ALSO

     getprotoent(3), services(5), services_mkdb(8)


HISTORY

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


BUGS

     These functions use static 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.

NetBSD 10.1                    December 03, 2022                   NetBSD 10.1