struct net_device之MAC

1.net_class_attrs(net-sysfs.c)static struct attribute *net_class_attrs[] = { &dev_attr_netdev_group.attr, &dev_attr_type.attr, &dev_attr_dev_id.attr, &dev_attr_iflink.attr, &dev_attr_ifindex.attr, &dev_attr_addr_assign_type.attr, &dev_attr_addr_len.attr, &dev_attr_link_mode.attr, &dev_attr_address.attr, &dev_attr_broadcast.attr, ...... NULL,};ATTRIBUTE_GROUPS(net_class);2.address attribute(net-sysfs.c)/* use same locking rules as GIFHWADDR ioctl's */static ssize_t address_show(struct device *dev, struct device_attribute *attr,char *buf){ struct net_device *net = to_net_dev(dev); ssize_t ret = -EINVAL; read_lock(&dev_base_lock); if (dev_isalive(net)) ret = sysfs_format_mac(buf, net->dev_addr, net->addr_len); read_unlock(&dev_base_lock); return ret;}static DEVICE_ATTR_RO(address);3.ARP MAC地址的获取来源static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb){....../*首先，每台主机都会在自己的ARP缓冲区中建立一个 ARP列表，以表示I P地址和MAC地址的对应关系。当源主机需要将一个数据包要发送到目的主机时，会首先检查自己 ARP列表中是否存在该 I P地址对应的MAC地址，如果有，就直接将数据包发送到这个MAC地址；如果没有，就向本地网段发起一个ARP请求的广播包，查询此目的主机对应的MAC地址。此ARP请求数据包里包括源主机的IP地址、硬件地址、以及目的主机的I P地址*/ arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, dst_hw, dev->dev_addr, NULL);//saddr:IP 地址 dev->dev_addr:MAC地址}struct arphdr { __be16 ar_hrd; /* format of hardware address */ __be16 ar_pro; /* format of protocol address */ unsigned char ar_hln; /* length of hardware address */ unsigned char ar_pln; /* length of protocol address */ __be16 ar_op; /* ARP opcode (command) */};static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,   unsigned short type,   const void *daddr, const void *saddr,   unsigned int len){ if (!dev->header_ops || !dev->header_ops->create) return 0; return dev->header_ops->create(skb, dev, type, daddr, saddr, len);}/* Interface to link layer: send routine and receive handler.*/ /* Create an arp packet. If (dest_hw == NULL), we create a broadcast message. */struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,    struct net_device *dev, __be32 src_ip,    const unsigned char *dest_hw,    const unsigned char *src_hw,    const unsigned char *target_hw){ struct sk_buff *skb; struct arphdr *arp; unsigned char *arp_ptr; ...... if (src_hw == NULL) src_hw = dev->dev_addr; /* Fill the device header for the ARP frame */ if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) goto out;...... arp_ptr = (unsigned char *)(arp + 1); memcpy(arp_ptr, src_hw, dev->addr_len); arp_ptr += dev->addr_len; memcpy(arp_ptr, &src_ip, 4); arp_ptr += 4;......}4.struct neighbour struct neighbour { unsigned char ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))];//MAC地址 ..... u8 primary_key[0];//IP地址};