C/C++应用系统升级支持IPv4/IPv6-金色坐标

C/C++应用系统升级支持IPv4/IPv6

1，作为Server端

类似于c#，IPv4/IPv6双协议栈环境中, 使用下面代码绑定到所有IP地址：

int ServSock, csock;
struct sockaddr addr, from;
...
ServSock = socket(AF_INET6, SOCK_STREAM, PF_INET6);
bind(ServSock, &addr, sizeof(addr));
do {
csock = accept(ServSocket, &from, sizeof(from));
doClientStuff(csock);
} while (!finished);

2，作为client端

类似c#，要想连接到IPv6服务器上，需指定ai_flags为 AI_ALL|AI_ADDRCONFIG。比如：

struct addrinfo *res, *aip;
struct addrinfo hints;
int sock = -1;
int error;

/* 获得服务器地址信息. */
bzero(&hints, sizeof(hints));
hints.ai_flags = AI_ALL|AI_ADDRCONFIG;
hints.ai_socktype = SOCK_STREAM;

error = getaddrinfo(hostname, servicename, &hints, &res);
if (error != 0) {
   (void) fprintf(stderr,
      "getaddrinfo: %s for host %s service %s\n",
      gai_strerror(error), hostname, servicename);
   return (-1);
}

/*尝试所有的地址，直到有一个成功 */
for (aip = res; aip != NULL; aip = aip->ai_next) {
   /*
   * 打开socket.地址的类型依赖于
   * getaddrinfo()的返回
   */
   sock = socket(aip->ai_family, aip->ai_socktype, aip->ai_protocol);
   if (sock == -1) {
      perror("socket");
      freeaddrinfo(res);
      return (-1);
   }

/*连接到服务器. */
if (connect(sock, aip->ai_addr, aip->ai_addrlen) == -1) {
   perror("connect");
   (void) close(sock);
   sock = -1;
   continue;
}
break;
}
   freeaddrinfo(res);