Question

我尝试通过SIOCADDRT和ioctl()设置我的计算机的默认网关。我在网上找到了以下代码片段：＃/ p>

int fd = socket( PF_INET, SOCK_DGRAM, IPPROTO_IP );

struct rtentry route;
memset( &route, 0, sizeof( route ) );

struct sockaddr_in *addr = (struct sockaddr_in *)&route.rt_gateway;
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = inet_addr( "10.0.2.2" );

addr = (struct sockaddr_in*) &route.rt_dst;
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = INADDR_ANY;

addr = (struct sockaddr_in*) &route.rt_genmask;
addr->sin_family = AF_INET;
addr->sin_addr.s_addr = INADDR_ANY;

// TODO Add the interface name to the request
route.rt_flags = RTF_UP | RTF_GATEWAY;
route.rt_metric = 0;

int rc = ioctl( fd, SIOCADDRT, &route );
// [...]

现在对于此代码段中的TODO ...您如何实际指定要使用的接口？当我执行此代码时，它似乎默认为我的机器上的eth0（这是我唯一的界面）。 rt_entry标题中route.h结构的定义如下（也可用here）：

   /* This structure gets passed by the SIOCADDRT and SIOCDELRT calls. */
   struct rtentry {
    unsigned long   rt_pad1;
    struct sockaddr rt_dst;     /* target address       */
    struct sockaddr rt_gateway; /* gateway addr (RTF_GATEWAY)   */
    struct sockaddr rt_genmask; /* target network mask (IP) */
    unsigned short  rt_flags;
    short       rt_pad2;
    unsigned long   rt_pad3;
    void        *rt_pad4;
    short       rt_metric;  /* +1 for binary compatibility! */
    char *rt_dev;   /* forcing the device at add    */
    unsigned long   rt_mtu;     /* per route MTU/Window     */
    #define rt_mss  rt_mtu          /* Compatibility :-(            */
    unsigned long   rt_window;  /* Window clamping      */
    unsigned short  rt_irtt;    /* Initial RTT          */
};

这是任何帮助。

Answer 1

显然，您可以使用两个字段来指定界面：

struct ifnet * rt_ifp;

struct ifaddr * rt_ifa;

这两个字段代表路线提出的问题的“答案”   抬头;也就是说，它们将接口和接口地址命名为   用于将数据包发送到目的地或目的地集   这条路线代表的是什么。

更新：在sturct中有一个rt_dev字段，我想你可以将它设置为接口名称：

char ifname[] = "eth1";
rtentry.rt_dev = ifname;

通过SIOCADDRT添加默认网关时指定接口

1 个答案: