inet_confirm_addr && confirm_addr_indev

 1 /* 2 ?* Confirm that local IP address exists using wildcards: 3 ?* - net: netns to check, cannot be NULL 4 ?* - in_dev: only on this interface, NULL=any interface 5 ?* - dst: only in the same subnet as dst, 0=any dst 6 ?* - local: address, 0=autoselect the local address 7 ?* - scope: maximum allowed scope value for the local address 8 ?*/ 9 10 /* 11 ????确认参数中给定的本地地址是否存在 12 ????net: net命名空间，不能为空13 ????in_dev: 在此ip控制块上，空表示任何设备上的控制块14 ????dst: 与dst在同一子网，0表示不限制15 ????local: 本地地址，0表示自动选择本地地址16 ????scope: 本地地址最大允许的地址范围17 */18 19 __be32 inet_confirm_addr(struct net *net, struct in_device *in_dev,20 ?????????????__be32 dst, __be32 local, int scope)21 {22 ????__be32 addr = 0;23 ????struct net_device *dev;24 25 ????/* ip控制块存在，则从该控制块中选择地址 */26 ????if (in_dev)27 ????????return confirm_addr_indev(in_dev, dst, local, scope);28 29 ????rcu_read_lock();30 ????/* ip控制块不存在，则遍历所有设备 */31 ????for_each_netdev_rcu(net, dev) {32 ????????/* 找到设备中的ip控制块 */33 ????????in_dev = __in_dev_get_rcu(dev);34 35 ????????/* 如果ip控制块存在 */36 ????????if (in_dev) {37 ????????????/* 从该控制块选择地址 */38 ????????????addr = confirm_addr_indev(in_dev, dst, local, scope);39 ????????????/* 找到则结束 */40 ????????????if (addr)41 ????????????????break;42 ????????}43 ????}44 ????rcu_read_unlock();45 46 ????return addr;47 }

 1 /* 2 ????从指定ip控制块中获取参数允许范围内的地址 3 ????1. local dst都不在，找一个满足范围的ip 4 ????2. local存在，dst不存在，找与local相等的满足范围的ip 5 ????3. local不存在，dst存在，找满足范围的与dst在同一子网的ip 6 ????4. local dst都存在，找与local相等，并且与dst在同一子网的ip 7 */ 8 static __be32 confirm_addr_indev(struct in_device *in_dev, __be32 dst, 9 ??????????????????__be32 local, int scope)10 {11 ????int same = 0;12 ????__be32 addr = 0;13 14 ????/* 遍历地址列表 */15 ????for_ifa(in_dev) {16 17 ????????if (!addr && /* 目标地址为空 */18 ????????????(local == ifa->ifa_local || !local) && /* 本地地址相等或者参数地址为空 */19 ????????????ifa->ifa_scope <= scope) { /* 当前地址满足<= 参数地址范围 */20 ????????????/* 找到目标地址 */21 ????????????addr = ifa->ifa_local;22 23 ????????????/* 满足子网要求 */24 ????????????if (same)25 ????????????????break;26 ????????}27 28 ????????/* 未判断子网是否相同 */29 ????????if (!same) {30 ????????????/* local dst不要求，或者在同一子网 */31 ????????????same = (!local || inet_ifa_match(local, ifa)) &&32 ????????????????(!dst || inet_ifa_match(dst, ifa));33 34 ????????????/* 满足子网要求且地址存在，则具体判断是哪种情况 */35 ????????????if (same && addr) {36 37 ????????????????/* local存在或者local和dst都不存在 */38 ????????????????if (local || !dst)39 ????????????????????break;40 41 ????????????????/* local不存在，dst存在 */42 ????????????????43 ????????????????/* Is the selected addr into dst subnet? */44 ????????????????/* 目标地址与dst在同一子网 */45 ????????????????if (inet_ifa_match(addr, ifa))46 ????????????????????break;47 48 ????????????????/* 目标地址与dst不在同一子网 */49 ????????????????50 ????????????????/* No, then can we use new local src? */51 ????????????????/* 如果ifa满足范围，则使用这个ifa的地址 */52 ????????????????if (ifa->ifa_scope <= scope) {53 ????????????????????addr = ifa->ifa_local;54 ????????????????????break;55 ????????????????}56 57 ????????????????/* 查找失败，继续查找 */58 ????????????????59 ????????????????/* search for large dst subnet for addr */60 ????????????????same = 0;61 ????????????}62 ????????}63 ????} endfor_ifa(in_dev);64 65 ????return same ? addr : 0;66 }