为什么我不能将ipv6套接字绑定到linklocal地址

Question

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>

void error(char *msg)
{
  perror(msg);
  exit(0);
}
int main(int argc, char *argv[])
{
   int sock, length, fromlen, n;
   struct sockaddr_in6 server;
   struct sockaddr_in6  from;

   int portNr = 5555;
   char buf[1024];

   length = sizeof (struct sockaddr_in6);

   sock=socket(AF_INET6, SOCK_DGRAM, 0);
   if (sock < 0) error("Opening socket");

   bzero((char *)&server, length);
   server.sin6_family=AF_INET6;
   server.sin6_addr=in6addr_any;
   server.sin6_port=htons(portNr);

   inet_pton( AF_INET6, "fe80::21f:29ff:feed:2f7e", (void *)&server.sin6_addr.s6_addr);
   //inet_pton( AF_INET6, "::1", (void *)&server.sin6_addr.s6_addr);

   if (bind(sock,(struct sockaddr *)&server,length)<0)
       error("binding");
   fromlen = sizeof(struct sockaddr_in6);
   while (1) {
       n = recvfrom(sock,buf,1024,0,(struct sockaddr *)&from,&fromlen);
       if (n < 0) error("recvfrom");
       write(1,"Received a datagram: ",21);
       write(1,buf,n);
       n = sendto(sock,"Got your message\n",17,
                  0,(struct sockaddr *)&from,fromlen);
       if (n  < 0) error("sendto");
   }
}

当我编译并运行上面的代码时,我得到了:

binding: Invalid argument

如果更改为绑定::1并在源代码中保持其他内容不变,则代码可以正常工作!所以你能告诉我我的代码有什么问题吗？提前致谢.

Answer 1

对于链接本地地址,还需要指定与地址关联的网络接口的范围ID ...如下所示:

server.sin6_scope_id = 5;   /* or whatever the scope ID is for the network interface you want to communicate over */

您可以使用getifaddrs()查找系统上可用的各种范围ID,以及它们对应的网络接口.

(是的,这很痛苦......或者你也可以在你传递给inet_pton()的字符串的末尾添加类似"%en0"的内容,而inet_pton()可能会为你工作......我我不确定inet_pton()是否处理​​该语法)