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ether_line (3)

>> ether_line (3) ( FreeBSD man: Библиотечные вызовы )

ether_line (3) ( Русские man: Библиотечные вызовы )

ether_line (3) ( Linux man: Библиотечные вызовы )

BSD mandoc

NAME



ethers

 
ether_line

 
ether_aton

 
ether_aton_r

 
ether_ntoa

 
ether_ntoa_r

 
ether_ntohost

 
ether_hostton

 - Ethernet address conversion and lookup routines

LIBRARY

Lb libc

SYNOPSIS

   #include <sys/types.h>
   #include <sys/socket.h>
   #include <net/ethernet.h>
int ether_line (const char *l struct ether_addr *e char *hostname);
struct ether_addr * ether_aton (const char *a);
struct ether_addr * ether_aton_r (const char *a struct ether_addr *e);
char * ether_ntoa (const struct ether_addr *n);
char * ether_ntoa_r (const struct ether_addr *n char *buf);
int ether_ntohost (char *hostname const struct ether_addr *e);
int ether_hostton (const char *hostname struct ether_addr *e);

DESCRIPTION

These functions operate on ethernet addresses using an Vt ether_addr structure, which is defined in the header file In netinet/if_ether.h :

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

/*
 * Structure of a 48-bit Ethernet address.
 */
struct  ether_addr {
        u_char octet[ETHER_ADDR_LEN];
};

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

The ether_aton ();
and ether_aton_r ();
functions convert ASCII representation of ethernet addresses into Vt ether_addr structures. Likewise, the ether_ntoa ();
and ether_ntoa_r ();
functions convert ethernet addresses specified as Vt ether_addr structures into ASCII strings.

The ether_ntohost ();
and ether_hostton ();
functions map ethernet addresses to their corresponding hostnames as specified in the /etc/ethers database. The ether_ntohost ();
function converts from ethernet address to hostname, and ether_hostton ();
converts from hostname to ethernet address.

RETURN VALUES

The ether_line ();
function returns zero on success and non-zero if it was unable to parse any part of the supplied line Fa l . It returns the extracted ethernet address in the supplied Vt ether_addr structure Fa e and the hostname in the supplied string Fa h .

On success, ether_ntoa ();
and ether_ntoa_r ();
functions return a pointer to a string containing an ASCII representation of an ethernet address. If it is unable to convert the supplied Vt ether_addr structure, it returns a NULL pointer. ether_ntoa ();
stores the result in a static buffer; ether_ntoa_r ();
stores the result in a user-passed buffer.

Likewise, ether_aton ();
and ether_aton_r ();
return a pointer to an Vt ether_addr structure on success and a NULL pointer on failure. ether_aton ();
stores the result in a static buffer; ether_aton_r ();
stores the result in a user-passed buffer.

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

NOTES

The user must insure that the hostname strings passed to the ether_line (,);
ether_ntohost ();
and ether_hostton ();
functions are large enough to contain the returned hostnames.

NIS INTERACTION

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

HISTORY

This particular implementation of the library functions were written for and first appeared in Fx 2.1 . Thread-safe function variants first appeared in Fx 7.0 .

BUGS

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

ether_ntoa_r ();
accepts a character buffer pointer, but not a buffer length. The caller must ensure adequate space is available in the buffer in order to avoid a buffer overflow.