IPV6 Socket 编程

原文：http://blog.csdn.net/caspiansea/article/details/29779655

写了一个 IPv6的服务端和客户端的程序，功能就是服务端重复一下客户端的输入（根据 UNP代码改的）。

代码如下：

server6.c:

 #include
 #include
 #include
 #include
 #include
 #include

 #define SERV_PORT        9877
 #define LISTENQ         1024
 extern int echo(int sockfd);
 int main(int argc, char ** argv)
 {
     int listenfd, connfd;
     struct sockaddr_in6 servaddr, cliaddr;

     listenfd = socket(AF_INET6, SOCK_STREAM, 0);

     if(listenfd == 0)
     {
         perror("socket create error");
         exit(1);
     }

     bzero(&servaddr, sizeof(servaddr));
     servaddr.sin6_family = AF_INET6;
     servaddr.sin6_addr = in6addr_any;
     servaddr.sin6_port = htons(SERV_PORT);

     if(bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1)
     {
         perror("bind error");
         exit(2);
     }

     if(listen(listenfd, LISTENQ) == -1)
     {
         perror("listen error");
         exit(3);
     }


     for(; ;)
     {
         socklen_t clien = sizeof(struct sockaddr);
         connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &clien);
         if(connfd == -1)
         {
             perror("accept error");
             exit(4);
         }

         pid_t childpid = fork();
         if(childpid == -1)
         {
             perror("fork error");
             exit(5);
         }
         else if(childpid == 0)
         {
             close(listenfd);
             echo(connfd);
             exit(0);
         }
         close(connfd);
     }
 }

client6.c:

 #include
 #include
 #include
 #include
 #include
 #include

 #define SERV_PORT  9877

 int main(int argc, char **argv)
 {
     int sockfd;
     struct sockaddr_in6 servaddr;

     if(argc != 2)
     {
         printf("usage: %s server address\n", argv[0]);
         exit(0);
     }


     sockfd = socket(AF_INET6, SOCK_STREAM, 0);

     if(sockfd == -1)
     {
         perror("socket error");
         exit(1);
     }

     bzero(&servaddr, sizeof(servaddr));
     servaddr.sin6_family = AF_INET6;
     servaddr.sin6_port = htons(SERV_PORT);

     int n = inet_pton(AF_INET6, argv[1], &servaddr.sin6_addr);
     if(n == 0)
     {
         fprintf(stderr, "not in presentation format\n");
         exit(2);
     }
     else if(n == -1)
     {
         perror("inet_pton error");
         exit(3);
     }

     printf("sizeof(servaddr) = %d\n", sizeof(servaddr));
     if(connect(sockfd, (struct sockaddr *)&servaddr, sizeof(struct sockaddr_in6)) == -1)
     {
         perror("connect error:");
         exit(4);
     }

     str_cli(stdin, sockfd);
     return 0;
 }

但是客户端在使用 IPv6地址连接服务器程序的时候，出现错误：

 t#./client6 fe80::5054:ff:fe12:3456
 connect error:: Invalid argument

fe80::5054:ff:fe12:3456 为 IPv6地址 (link-local).

但是加上一个其它类型的地址 (如global 的），然后，  client就能连上了。

 sudo ip addr add 2001:470:1f01:f52b::2/64 dev wlan0
 or
 sudo ifconfig wlan0 inet6 add 2001:470:1f01:f52b::2/64

 wlan0     Link encap:Ethernet  HWaddr ec:55:f9:bf:7c:16
           inet addr:192.168.1.102  Bcast:192.168.1.255  Mask:255.255.255.0
           inet6 addr: fe80::ee55:f9ff:febf:7c16/64 Scope:Link
           inet6 addr: 2001:470:1f01:f52b::2/64 Scope:Global
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:2445788 errors:0 dropped:0 overruns:0 frame:0
           TX packets:1667005 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:2493540196 (2.4 GB)  TX bytes:284771192 (284.7 MB)

 ./client6 2001:470:1f01:f52b::2
 sizeof(servaddr) = 28
 1
 1

网上有资料说

  You got a bit more to cover to get up and flying with IPv6. Like you
 should NOT be using Link Local addresses for anything in user space (they're
 primarily used in the kernel and lower level protocol stuff for things like
 neighbor discovery and router solicitation. You can use them with certain
 apps, like ping6, IF you know what you are doing. But not with apps which
 don't understand what you are doing.

References:

http://www.derkeiler.com/Mailing-Lists/securityfocus/Secure_Shell/2004-01/0013.html
http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/index.html
http://www.bieringer.de/linux/IPv6/IPv6-HOWTO/IPv6-HOWTO-6.html

https://wiki.ubuntu.com/IPv6