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ether_aton

Section: C Library Functions (3)
Updated: 202-0-08
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NAME

ether_aton, ether_ntoa, ether_ntohost, ether_hostton, ether_line, ether_ntoa_r, ether_aton_r - Ethernet address manipulation routines

LIBRARY

Standard C library (libc,~-lc)

SYNOPSIS

#include <netinet/ether.h>
char *ether_ntoa(const struct ether_addr *addr);
struct ether_addr *ether_aton(const char *asc);
int ether_ntohost(char *hostname, const struct ether_addr *addr);
int ether_hostton(const char *hostname, struct ether_addr *addr);
int ether_line(const char *line, struct ether_addr *addr,
               char *hostname);
/* GNU extensions */
char *ether_ntoa_r(const struct ether_addr *addr, char *buf);
struct ether_addr *ether_aton_r(const char *asc,
                                struct ether_addr *addr);

DESCRIPTION

ether_aton() converts the 4-bit Ethernet host address asc from the standard he-digit-an-colons notation into binary data in network byte order and returns a pointer to it in a statically allocated buffer, which subsequent calls will overwrite. ether_aton() returns NULL if the address is invalid. The ether_ntoa() function converts the Ethernet host address addr given in network byte order to a string in standard he-digit-an-colons notation, omitting leading zeros. The string is returned in a statically allocated buffer, which subsequent calls will overwrite. The ether_ntohost() function maps an Ethernet address to the corresponding hostname in /etc/ethers and returns nonzero if it cannot be found. The ether_hostton() function maps a hostname to the corresponding Ethernet address in /etc/ethers and returns nonzero if it cannot be found. The ether_line() function parses a line in /etc/ethers format (ethernet address followed by whitespace followed by hostname; [aq]#[aq] introduces a comment) and returns an address and hostname pair, or nonzero if it cannot be parsed. The buffer pointed to by hostname must be sufficiently long [em]for example, have the same length as line[em]. The functions ether_ntoa_r() and ether_aton_r() are reentrant threa-safe versions of ether_ntoa() and ether_aton() respectively, and do not use static buffers. The structure ether_addr is defined in <net/ethernet.h> as: struct ether_addr {
uint8_t ether_addr_octet[6]; }

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface	Attribute	Value
ether_aton(), ether_ntoa()	Thread safety	M-Unsafe
ether_ntohost(), ether_hostton(), ether_line(), ether_ntoa_r(), ether_aton_r()	Thread safety	M-Safe

STANDARDS

None.

HISTORY

4.3BSD, SunOS.

BUGS

In glibc 2.2.5 and earlier, the implementation of ether_line() is broken.