【Linux】【网络】struct ether_addr和字符串格式转换

数据结构struct ether_addr定义在uClib库中头文件ethernet.h中，用来描述MAC地址的6字节以太网地址，定义如下：

/* This is a name for the 48 bit ethernet address available on many
systems. */
struct ether_addr
{
u_int8_t ether_addr_octet[ETH_ALEN];
} __attribute__ ((__packed__));

在实际的使用中，很多时候需要将该地址转换成字符串格式（XX:XX:XX:XX:XX:XX或XX-XX-XX-XX-XX-XX格）的MAC地址，接口函数如下：
/*将格式为struct ehter_addr格式的地址staAddr转换成冒号分隔格式的MAC地址，并返回转换后MAC地址的内存地址*/
static const char *mac2str(const struct ether_addr staAddr)
{
static char a[18];
int i;
i = snprintf(a, sizeof(a), "%02x:%02x:%02x:%02x:%02x:%02x",
staAddr.ether_addr_octet[0], staAddr.ether_addr_octet[1],
staAddr.ether_addr_octet[2], staAddr.ether_addr_octet[3],
staAddr.ether_addr_octet[4], staAddr.ether_addr_octet[5]);
return (i < 17 ? NULL : a);
}


/*将冒号XX:XX:XX:XX:XX:XX或者XX-XX-XX-XX-XX-XX格式的MAC地址转换成struct ether_addr格式 */
static int str2mac(const char *buffer, struct ether_addr *etheraddr)
{
int i, c;
if (NULL == buffer || NULL == etheraddr || strlen(buffer) != 17)
{
return ERROR;
}
for (i = 0; i < 6; i++)
{
if (*buffer == '-' || *buffer == ':')
{
buffer++;
}
if (*buffer >= '0' && *buffer <= '9')
{
c = (unsigned char) (*buffer++ - '0');
}
else if (*buffer >= 'a' && *buffer <= 'f')
{
c = (unsigned char) (*buffer++ - 'a') + 10;
}
else if (*buffer >= 'A' && *buffer <= 'F')
{
c = (unsigned char) (*buffer++ - 'A') + 10;
}
else
{
return ERROR;
}
c <<= 4;
if (*buffer >= '0' && *buffer <= '9')
{
c |= (unsigned char) (*buffer++ - '0');
}
else if (*buffer >= 'a' && *buffer <= 'f')
{
c |= (unsigned char) (*buffer++ - 'a') + 10;
}
else
{
c |= (unsigned char) (*buffer++ - 'A') + 10;
}
etheraddr->ether_addr_octet[i] = (unsigned char) c;
}
return OK;
}