ether_aton(3) - NetBSD Manual Pages

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ETHERS(3)                 NetBSD Programmer's Manual                 ETHERS(3)


NAME

     ether_ntoa, ether_aton, ether_ntohost, ether_hostton, ether_line, - get
     ethers entry


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <net/if_ether.h>

     char *
     ether_ntoa(struct ether_addr *e);

     struct ether_addr *
     ether_aton(const char *s);

     int
     ether_ntohost(char *hostname, struct ether_addr *e);

     int
     ether_hostton(const char *hostname, struct ether_addr *e);

     int
     ether_line(const char *line, struct ether_addr *e, char *hostname);


DESCRIPTION

     Ethernet addresses are represented by the following structure:

           struct ether_addr {
                   u_char  ether_addr_octet[6];
           };

     The ether_ntoa() function converts this structure into an ASCII string of
     the form ``xx:xx:xx:xx:xx:xx'', consisting of 6 hexadecimal numbers sepa-
     rated by colons.  It returns a pointer to a static buffer that is reused
     for each call.  The ether_aton() converts an ASCII string of the same
     form and to a structure containing the 6 octets of the address.  It re-
     turns a pointer to a static structure that is reused for each call.

     The ether_ntohost() and ether_hostton() functions interrogate the data
     base mapping host names to Ethernet addresses, /etc/ethers.  The
     ether_ntohost() function looks up the given Ethernet address and writes
     the associated host name into the character buffer passed.  The
     ether_hostton() function looks up the given host name and writes the as-
     sociated Ethernet address into the structure passed.  Both functions re-
     turn zero if they find the requested host name or address, and -1 if not.
     Each call reads /etc/ethers from the beginning; if a + appears alone on a
     line in the file, then ether_hostton() will consult the ethers.byname YP
     map, and ether_ntohost() will consult the ethers.byaddr YP map.

     The ether_line() function parses a line from the /etc/ethers file and
     fills in the passed ``struct ether_addr'' and character buffer with the
     Ethernet address and host name on the line.  It returns zero if the line
     was successfully parsed and -1 if not.

     The hostname buffer for ether_line() and ether_ntohost() should be at
     least MAXHOSTNAMELEN + 1 characters long, to prevent a buffer overflow
     during parsing.


FILES

     /etc/ethers


SEE ALSO

     ethers(5)


HISTORY

     The ether_ntoa(), ether_aton(), ether_ntohost(), ether_hostton(), and
     ether_line() functions were adopted from SunOS and appeared in
     NetBSD 1.0.


BUGS

     The data space used by these functions is static; if future use requires
     the data, it should be copied before any subsequent calls to these func-
     tions overwrite it.

NetBSD 1.4                     November 2, 1997                              2