我对IPv6协议知之甚少,很抱歉,这个问题听起来很愚蠢.

当我检索网络中所有IPv6地址的列表时,我得到一个名为scope的字段,如下所示：

inet6 addr: 2001:470:1:82::11/64 Scope:Global

inet6 addr: 2001:470:1:82::10/64 Scope:Global

inet6 addr: 2001:470:1:82::13/64 Scope:Global

inet6 addr: fe80::21d:9ff:fe69:2c50/64 Scope:Link

inet6 addr: 2001:470:1:82::12/64 Scope:Global

inet6 addr: 2001:470:1:82::15/64 Scope:Global

inet6 addr: 2001:470:1:82::14/64 Scope:Global

inet6 addr: 2001:470:1:82::5/64 Scope:Global

inet6 addr: 2001:470:1:82::17/64 Scope:Global

inet6 addr: 2001:470:1:82::6/64 Scope:Global

inet6 addr: 2001:470:1:82::16/64 Scope:Global

inet6 addr: 2001:470:1:82::7/64 Scope:Global

inet6 addr: 2001:470:1:82::19/64 Scope:Global

inet6 addr: 2001:470:1:82::8/64 Scope:Global

inet6 addr: 2001:470:1:82::18/64 Scope:Global

inet6 addr: 2001:470:1:82::9/64 Scope:Global

inet6 addr: 2001:470:1:82::1b/64 Scope:Global

inet6 addr: 2001:470:1:82::a/64 Scope:Global

inet6 addr: 2001:470:1:82::1a/64 Scope:Global

inet6 addr: 2001:470:1:82::b/64 Scope:Global

inet6 addr: 2001:470:1:82::1d/64 Scope:Global

inet6 addr: 2001:470:1:82::c/64 Scope:Global

inet6 addr: 2001:470:1:82::1c/64 Scope:Global

inet6 addr: 2001:470:1:82::d/64 Scope:Global

inet6 addr: 2001:470:1:82::1f/64 Scope:Global

inet6 addr: 2001:470:1:82::e/64 Scope:Global

inet6 addr: 2001:470:1:82::1e/64 Scope:Global

inet6 addr: 2001:470:1:82::f/64 Scope:Global

inet6 addr: ::1/128 Scope:Host

在我的应用程序中,我需要获取范围为“链接”的那些地址.我可以使用系统调用ifconfig然后解析输出以提取相应的地址.但问题是,我正在使用getifaddrs()调用,它返回结构ifaddr的链表,给出如下：

struct ifaddrs {

struct ifaddrs *ifa_next; /* Next item in list */

char *ifa_name; /* Name of interface */

unsigned int ifa_flags; /* Flags from SIOCGIFFLAGS */

struct sockaddr *ifa_addr; /* Address of interface */

struct sockaddr *ifa_netmask; /* Netmask of interface */

union {

struct sockaddr *ifu_broadaddr;

/* Broadcast address of interface */

struct sockaddr *ifu_dstaddr;

/* Point-to-point destination address */

} ifa_ifu;

#define ifa_broadaddr ifa_ifu.ifu_broadaddr

#define ifa_dstaddr ifa_ifu.ifu_dstaddr

void *ifa_data; /* Address-specific data */

};

问题是：如何从此列表中获取具有“链接”范围的地址？

解决方法:

一种方法是检查地址是否在fe80 :: / 10范围内. IPv6 address space可从IANA获取,详细说明了可用的范围.

我将源代码下载到net-tools(ifconfig的源包),它们看起来像是解析/ proc / net / if_inet6. (注释是我自己在以下代码中添加的内容 – 以下内容也非常简略,并且肯定不会编译.)

/* some defines collected around the place: */

#define _PATH_PROCNET_IFINET6 "/proc/net/if_inet6"

#define IPV6_ADDR_LOOPBACK 0x0010U

#define IPV6_ADDR_LINKLOCAL 0x0020U

#define IPV6_ADDR_SITELOCAL 0x0040U

#define IPV6_ADDR_COMPATv4 0x0080U

int scope; /* among other stuff */

/* looks like here we parse the contents of /proc/net/if_inet6: */

if ((f = fopen(_PATH_PROCNET_IFINET6, "r")) != NULL) {

while (fscanf(f, "%4s%4s%4s%4s%4s%4s%4s%4s %02x %02x %02x %02x %20s\n",

addr6p[0], addr6p[1], addr6p[2], addr6p[3],

addr6p[4], addr6p[5], addr6p[6], addr6p[7],

&if_idx, &plen, &scope, &dad_status, devname) != EOF) {

/* slightly later: */

printf(_(" Scope:"));

switch (scope) {

case 0:

printf(_("Global"));

break;

case IPV6_ADDR_LINKLOCAL:

printf(_("Link"));

break;

case IPV6_ADDR_SITELOCAL:

printf(_("Site"));

break;

case IPV6_ADDR_COMPATv4:

printf(_("Compat"));

break;

case IPV6_ADDR_LOOPBACK:

printf(_("Host"));

break;

default:

printf(_("Unknown"));

}

那么让我们来看看上面解析的内容：

$cat /proc/net/if_inet6

20010db8000008000000000000000001 03 40 00 00 eth0

fe800000000000000000000000004321 03 40 20 80 eth0

00000000000000000000000000000001 01 80 10 80 lo

因此,您可以看到左侧的第三列(0x00 Global,0x20 Link-Local和0x10 Loopback)是范围.使用网络工具代码中的上述常量,您可以找出它们的含义.需要进一步调查以确定这些常量的更权威的来源,以及解析/ proc / net / if_inet6是否是您的最佳选择.

标签：bash,linux,ip-address,ipv6

来源： https://codeday.me/bug/20190714/1461406.html