ETHERS(3) BSD Library Functions Manual ETHERS(3)

NAME
     eetthheerrss, eetthheerrlliinnee, eetthheerraattoonn, eetthheerrnnttooaa, eetthheerrnnttoohhoosstt, eetthheerrhhoossttttoonn
     - Ethernet address conversion and lookup routines

LLIIBBRRAARRYY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##iinncclluuddee <>
     ##iinncclluuddee <>
     ##iinncclluuddee <>

     int
     eetthheerrlliinnee(const char *l, struct etheraddr *e, char *hostname);

     struct etheraddr *
     eetthheerraattoonn(const char *a);

     char *
     eetthheerrnnttooaa(const struct etheraddr *n);

     int
     eetthheerrnnttoohhoosstt(char *hostname, const struct etheraddr *e);

     int
     eetthheerrhhoossttttoonn(const char *hostname, struct etheraddr *e);

DESCRIPTION
     These functions operate on ethernet addresses using an etheraddr struc-
     ture, which is defined in the header file :

           /*
            * The number of bytes in an ethernet (MAC) address.
            */
           #define ETHERADDRLEN          6

           /*
            * Structure of a 48-bit Ethernet address.
            */
           struct  etheraddr {
                   uchar octet[ETHERADDRLEN];
           };

     The function eetthheerrlliinnee() scans l, an ASCII string in ethers(5) format
     and sets e to the ethernet address specified in the string and h to the
     hostname.  This function is used to parse lines from /etc/ethers into
     their component parts.

     The eetthheerraattoonn() function converts an ASCII representation of an ethernet
     address into an etheraddr structure.  Likewise, eetthheerrnnttooaa() converts an
     ethernet address specified as an etheraddr structure into an ASCII
     string.

     The eetthheerrnnttoohhoosstt() and eetthheerrhhoossttttoonn() functions map ethernet addresses
     to their corresponding hostnames as specified in the /etc/ethers data-
     base.  eetthheerrnnttoohhoosstt() converts from ethernet address to hostname, and
     eetthheerrhhoossttttoonn() converts from hostname to ethernet address.

RETURN VALUES
     eetthheerrlliinnee() returns zero on success and non-zero if it was unable to
     parse any part of the supplied line l.  It returns the extracted ethernet
     address in the supplied etheraddr structure e and the hostname in the
     supplied string h.

     On success, eetthheerrnnttooaa() returns a pointer to a string containing an
     ASCII representation of an ethernet address.  If it is unable to convert
     the supplied etheraddr structure, it returns a NULL pointer.  Likewise,
     eetthheerraattoonn() returns a pointer to an etheraddr structure on success and
     a NULL pointer on failure.

     The eetthheerrnnttoohhoosstt() and eetthheerrhhoossttttoonn() functions both return zero on
     success or non-zero if they were unable to find a match in the
     /etc/ethers database.

NNOOTTEESS
     The user must insure that the hostname strings passed to the
     eetthheerrlliinnee(), eetthheerrnnttoohhoosstt() and eetthheerrhhoossttttoonn() functions are large
     enough to contain the returned hostnames.

NNIISS IINNTTEERRAACCTTIIOONN
     If the /etc/ethers contains a line with a single + in it, the
     eetthheerrnnttoohhoosstt() and eetthheerrhhoossttttoonn() functions will attempt to consult the
     NIS ethers.byname and ethers.byaddr maps in addition to the data in the
     /etc/ethers file.

SEE ALSO
     yp(4), ethers(5)

BUGS
     The eetthheerraattoonn() and eetthheerrnnttooaa() functions returns values that are
     stored in static memory areas which may be overwritten the next time they
     are called.

HISTORY
     This particular implementation of the eetthheerrss library functions were writ-
     ten for and first appeared in FreeBSD 2.1.

BSD                             April 12, 1995                             BSD