|
 面已经分析 ， 接口添进网桥时， 户空间调ioctl(br_socket_fd, SIOCBRADDIF, &ifr)注意  void br_dev_setup(struct net_device *dev) 已经 dev->do_ioctl进行赋值，即：dev->do_ioctl = br_dev_ioctl进行ioctl进行访问 时候，进入br_dev_ioctl: (net/brige/br_ioctl.c)int br_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
{
struct net_bridge *br = netdev_priv(dev);
switch(cmd) {
case SIOCDEVPRIVATE:
return old_dev_ioctl(dev, rq, cmd);
//添加 个接口
case SIOCBRADDIF:
// 除个接口
case SIOCBRDELIF:
return add_del_if(br, rq->ifr_ifindex, cmd == SIOCBRADDIF);
}
pr_debug("Bridge does not support ioctl 0x%xn", cmd);
return -EOPNOTSUPP;
}
 们户空间使标志 SIOCBRADDIF。所以流程进入add_del_if()static int add_del_if(struct net_bridge *br, int ifindex, int isadd)
{
struct net_device *dev;
int ret;
if (!capable(CAP_NET_ADMIN))
return -EPERM;
dev = dev_get_by_index(ifindex);
if (dev == NULL)
return -EINVAL;
if (isadd)
ret = br_add_if(br, dev);
else
ret = br_del_if(br, dev);
dev_put(dev);
return ret;
}
 cmd == SIOCBRADDIF真，所以调br_add_if():int br_add_if(struct net_bridge *br, struct net_device *dev) (net/brige/br_if.c))
{
struct net_bridge_port *p;
int err = 0;
//回环。或 非以及网接口
if (dev->flags & IFF_LOOPBACK || dev->type != ARPHRD_ETHER)
return -EINVAL;
//构造数据包函数网桥类型
if (dev->hard_start_xmit == br_dev_xmit)
return -ELOOP;
//此接口已经存于网桥
if (dev->br_port != NULL)
return -EBUSY;
//dev 创建网桥接口.dev->br_port。指向所属网桥端口
//dev->br_port->br：指向 所属网桥
//该接口创建net_bridge_port
if (IS_ERR(p = new_nbp(br, dev, br_initial_port_cost(dev))))
return PTR_ERR(p);
//更新port->MAC应表
if ((err = br_fdb_insert(br, p, dev->dev_addr, 1)))
destroy_nbp(p);
else if ((err = br_sysfs_addif(p)))
del_nbp(p);
else {
//设置接口混杂模式
dev_set_promiscuity(dev, 1);
//p->list更新至br->port_list
list_add_rcu(&p->list, &br->port_list);
spin_lock_bh(&br->lock);
br_stp_recalculate_bridge_id(br);
if ((br->dev->flags & IFF_UP)
&& (dev->flags & IFF_UP) && netif_carrier_ok(dev))
br_stp_enable_port(p);
spin_unlock_bh(&br->lock);
dev_set_mtu(br->dev, br_min_mtu(br));
}
return err;
}
接口创建net_bridge_port函数new_nbp。这个函数比较简单：static struct net_bridge_port *new_nbp(struct net_bridge *br,
struct net_device *dev,
unsigned long cost)
{
int index;
struct net_bridge_port *p;
index = find_portno(br);
if (index < 0)
return ERR_PTR(index);
p = kmalloc(sizeof(*p), GFP_KERNEL);
if (p == NULL)
return ERR_PTR(-ENOMEM);
memset(p, 0, sizeof(*p));
p->br = br;
dev_hold(dev);
p->dev = dev;
p->path_cost = cost;
p->priority = 0x8000 >> BR_PORT_BITS;
dev->br_port = p;
p->port_no = index;
br_init_port(p);
p->state = BR_STATE_DISABLED;
kobject_init(&p->kobj);
return p;
}   ，  加入接口应mac 接口作本机静态项加入prot—mac应表。这br_fdb_insert()实现int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
const unsigned char *addr, int is_local)
{
int ret;
spin_lock_bh(&br->hash_lock);
ret = fdb_insert(br, source, addr, is_local);
spin_unlock_bh(&br->hash_lock);
return ret;
}
static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
const unsigned char *addr, int is_local)
{
struct hlist_node *h;
struct net_bridge_fdb_entry *fdb;
int hash = br_mac_hash(addr);
//判断否有效mac 地址
if (!is_valid_ether_addr(addr))
return -EADDRNOTAVAIL;
hlist_for_each_entry(fdb, h, &br->hash[hash], hlist) {
//如果表已经包含此项
if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
//如果本机MAC
/* attempt to update an entry for a local interface */
if (fdb->is_local) {
/* it is okay to have multiple ports with same
* address, just don't allow to be spoofed.
*/
if (is_local)
return 0;
if (net_ratelimit())
printk(KERN_WARNING "%s: received packet with "
" own address as source addressn",
source->dev->name);
return -EEXIST;
}
//如果添加本机IP
if (is_local) {
printk(KERN_WARNING "%s adding interface with same address "
"as a received packetn",
source->dev->name);
goto update;
}
//如果添加静态MAC
//则不更新相关信息
if (fdb->is_static)
return 0;
/* move to end of age list */
list_del(&fdb->u.age_list);
goto update;
}
}
fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
if (!fdb)
return ENOMEM;
memcpy(fdb->addr.addr, addr, ETH_ALEN);
atomic_set(&fdb->use_count, 1);
hlist_add_head_rcu(&fdb->hlist, &br->hash[hash]);
if (!timer_pending(&br->gc_timer)) {
br->gc_timer.expires = jiffies + hold_time(br);
add_timer(&br->gc_timer);
}
update:
fdb->dst = source;
fdb->is_local = is_local;
fdb->is_static = is_local;
fdb->ageing_timer = jiffies;
if (!is_local)
list_add_tail(&fdb->u.age_list, &br->age_list);
return 0;
}
 分析 net_bridge_port结构：struct net_bridge_port
{
//当端口所briage
struct net_bridge *br;
//此端口应物理端口
struct net_device *dev;
//同桥 端口链表？
struct list_head list;
/* STP */
u8 priority;
u8 state;
u16 port_no;
unsigned char topology_change_ack;
unsigned char config_pending;
port_id port_id;
port_id designated_port;
bridge_id designated_root;
bridge_id designated_bridge;
u32 path_cost;
u32 designated_cost;
struct timer_list forward_delay_timer;
struct timer_list hold_timer;
struct timer_list message_age_timer;
struct kobject kobj;
struct rcu_head rcu;
};
//CAM表应数据结构
struct net_bridge_fdb_entry
{
//于CAM表连接链表指针
struct hlist_node hlist;
//此项应物理出口
struct net_bridge_port *dst;
union {
struct list_head age_list;
struct rcu_head rcu;
} u;
//此项当引计数
atomic_t use_count;
//超时时间
unsigned long ageing_timer;
//MAC地址
mac_addr addr;
//否主机地址
unsigned char is_local;
//否静态地址
unsigned char is_static;
};
struct net_bridge_port
{
//当端口所briage
struct net_bridge *br;
//此端口应物理端口
struct net_device *dev;
//同桥端口链表？
struct list_head list;
/* STP */
u8 priority;
u8 state;
u16 port_no;
unsigned char topology_change_ack;
unsigned char config_pending;
port_id port_id;
port_id designated_port;
bridge_id designated_root;
bridge_id designated_bridge;
u32 path_cost;
u32 designated_cost;
struct timer_list forward_delay_timer;
struct timer_list hold_timer;
struct timer_list message_age_timer;
struct kobject kobj;
struct rcu_head rcu;};
这样，就往桥添加个接口，从 图 以反应出接口桥间关系。们以brctl show指令看当所有桥，以及桥里相应接口。ifconfig br0以看当桥状态，如果细心点以看，bro已经有应MAC。这怎么呢？桥MAC地址更新：注意br_add_if调函数br_stp_recalculate_bridge_id()面代码分析，简化分析，stp相关流程忽略掉，现们看这个函数做些什么/* called under bridge lock */
void br_stp_recalculate_bridge_id(struct net_bridge *br)
{
const unsigned char *addr = br_mac_zero;
struct net_bridge_port *p;
//遍历桥所有端口
list_for_each_entry(p, &br->port_list, list) {
// 所有接口MAC最少值
if (addr == br_mac_zero ||
memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
addr = p->dev->dev_addr;
}
//如果不现桥MAC相同
if (memcmp(br->bridge_id.addr, addr, ETH_ALEN))
br_stp_change_bridge_id(br, addr);
}
 MAC。然判断最MAC跟现MAC否相同继续跟踪br_stp_change_bridge_idstatic void br_stp_change_bridge_id(struct net_bridge *br,
const unsigned char *addr)
{
unsigned char oldaddr[6];
struct net_bridge_port *p;
int wasroot;
wasroot = br_is_root_bridge(br);
memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
memcpy(br->bridge_id.addr, addr, ETH_ALEN);
//注意这里，呵呵，桥MAC更新
memcpy(br->dev->dev_addr, addr, ETH_ALEN);
list_for_each_entry(p, &br->port_list, list) {
if (!memcmp(p->designated_bridge.addr, oldaddr, ETH_ALEN))
memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
if (!memcmp(p->designated_root.addr, oldaddr, ETH_ALEN))
memcpy(p->designated_root.addr, addr, ETH_ALEN);
}
br_configuration_update(br);
br_port_state_selection(br);
if (br_is_root_bridge(br) && !wasroot)
br_become_root_bridge(br);
}
看 面 注释 吧，桥 MAC就 这里得 更新 ，所以，桥 MAC地址 得 所有接口 最 值 网桥 接收数据 处理： 回本章开始handle_bridge函数， 调br_handle_frame_hook进行接收数据处理网桥 始化代码，br_handle_frame_hook赋值br_handle_frame没 ，这就网桥处理函数。跟进个函数nt br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb)
{
struct sk_buff *skb = *pskb;
//目mac地址
const unsigned char *dest = eth_hdr(skb)->h_dest;
//端口禁
if (p->state == BR_STATE_DISABLED)
goto err;
//源mac  播或广播，丢弃
//FF.XX.XX.XX.XX.XX形式
if (eth_hdr(skb)->h_source[0] & 1)
goto err;
//如果状态学习或转发，则学习源mac 更新CAM 表
if (p->state == BR_STATE_LEARNING ||
p->state == BR_STATE_FORWARDING)
// br_fdb_insert函数们面已经分析过
br_fdb_insert(p->br, p, eth_hdr(skb)->h_source, 0);
//stp 处理,stp-enabled 否启stp 协议
//bridge_ula stp使播mac地址
if (p->br->stp_enabled &&
!memcmp(dest, bridge_ula, 5) &&
!(dest[5] & 0xF0)) {
if (!dest[5]) {
NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
NULL, br_stp_handle_bpdu);
return 1;
}
}
else if (p->state == BR_STATE_FORWARDING) {
//始化，并末br_should_route_hook进行赋值
//所以br_should_route_hook假
if (br_should_route_hook) {
if (br_should_route_hook(pskb))
return 0;
skb = *pskb;
dest = eth_hdr(skb)->h_dest;
}
//目地址桥地址相同。则传层处理
//置skb->pkt_type = PACKET_HOST
if (!memcmp(p->br->dev->dev_addr, dest, ETH_ALEN))
skb->pkt_type = PACKET_HOST;
//网桥NF_BR_PRE_ROUTING点netfiter处理
NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
br_handle_frame_finish);
return 1;
}
err:
kfree_skb(skb);
return 1;
} 这个函数里，进行相关入口判断，当数据包源MAC接口应更新CAM表，更新函数br_fdb_insert()面已经分析过，不太明白以倒过去看，不过注意，这不做静态项插入。接着判断包不传给本机，如果，则置包pkt_typePACKET_HOST关于NF_HOOK()宏，们以netfiter有专题分析。这们只知道， 常数据包流进br_handle_frame_finish()进行处理/* note: already called with rcu_read_lock (preempt_disabled) */
int br_handle_frame_finish(struct sk_buff *skb)
{
//得目MAC地址
const unsigned char *dest = eth_hdr(skb)->h_dest;
struct net_bridge_port *p = skb->dev->br_port;
struct net_bridge *br = p->br;
struct net_bridge_fdb_entry *dst;
int passedup = 0;
//混杂模式
/*如果网桥虚拟网卡处于混杂模式，那么每个接收数据包都需克隆份
送AF_PACKET协议处理体(网络软断函数net_rx_actionptype_all链处理)。*/
if (br->dev->flags & IFF_PROMISC) {
struct sk_buff *skb2;
skb2 = skb_clone(skb, GFP_ATOMIC);
if (skb2 != NULL) {
passedup = 1;
br_pass_frame_up(br, skb2);
}
}
//目mac 播或广播,则需传至层进行处理
//passedup传送标志，1 时表示已经传过
if (dest[0] & 1) {
br_flood_forward(br, skb, !passedup);
if (!passedup)
br_pass_frame_up(br, skb);
goto out;
}
//查询CAM 表
dst = __br_fdb_get(br, dest);
//本机？ 传至层协议处理
if (dst != NULL && dst->is_local) {
if (!passedup)
br_pass_frame_up(br, skb);
else
kfree_skb(skb);
goto out;
}
//不本机数据，则转发
if (dst != NULL) {
br_forward(dst->dst, skb);
goto out;
}
//如果查询不，其端口都发送此包
br_flood_forward(br, skb, 0);
out:
return 0;
}
struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
const unsigned char *addr)
{
struct hlist_node *h;
struct net_bridge_fdb_entry *fdb;
//遍历应MAC哈希项fdb
hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
if (unlikely(has_expired(br, fdb)))
break;
return fdb;
}
}
return NULL;
}
这个函数非常容易，首先 得目 MAC 应 哈希项。然 再遍历里面 数据，查看 否含有目 地址 项。如果 送给本机 数据包，则传至 层协议，如不 ，则需 转发。 |
