socket支持ipv6

转自：https://www.jianshu.com/p/9926b99a7fef

以前cocos2d-x的项目里都使用的是libwebsocket，如果想支持ipv6，只需要升级相应的库即可，现在有个项目里使用的是原生socket，如果要支持ipv6可能需要进行一些代码的改造，具体可参考如下代码：

struct addrinfo *result;
struct addrinfo *res;

struct addrinfo addrCriteria;
memset(&addrCriteria,0,sizeof(addrCriteria));
addrCriteria.ai_family=AF_UNSPEC;
addrCriteria.ai_socktype=SOCK_STREAM;
addrCriteria.ai_protocol=IPPROTO_TCP;

//判定网络类型    指定特定接口信息  
int error = getaddrinfo("www.baidu.com", "1100", &addrCriteria, &result);
if (error == 0)
{
    struct sockaddr_in *sa;
    for (res = result; res != NULL; res = res->ai_next)
    {
        if (AF_INET6 == res->ai_addr->sa_family)
        {
            char buf[128] = {};
            sa = (struct sockaddr_in*)res->ai_addr;
            inet_ntop(AF_INET6, &((reinterpret_cast<struct sockaddr_in6*>(sa))->sin6_addr), buf, 128);

            m_sock = socket(res->ai_family, res->ai_socktype, 0);
            if (m_sock == -1) {
                log("error socket create");
                return;
            }

            struct sockaddr_in6 svraddr;
            memset(&svraddr, 0, sizeof(svraddr)); //注意初始化  
            svraddr.sin6_family = AF_INET6;
            svraddr.sin6_port = htons(port);
            if (inet_pton(AF_INET6,buf,&svraddr.sin6_addr) < 0)
            {
                log("error addr");
            }
            int ret = connect(m_sock, (struct sockaddr*) &svraddr, sizeof(svraddr));
            //TODO....遇到IPv6就退出  
            break;
        }
        else if (AF_INET == res->ai_addr->sa_family)
        {
            char buf[32] = {};
            sa = (struct sockaddr_in*)res->ai_addr;
            inet_ntop(AF_INET, &sa->sin_addr), buf, 32);

            m_sock = socket(res->ai_family, res->ai_socktype, 0);
            if (m_sock == -1) {
                log("error socket create");
                return;
            }

            struct sockaddr_in svraddr;
            svraddr.sin_family = AF_INET;
            svraddr.sin_addr.s_addr = inet_addr(buf);
            svraddr.sin_port = htons(port);
            int ret = connect(m_sock, (struct sockaddr*) &svraddr, sizeof(svraddr));
            //TODO.... break除掉
            //break;  
        }
    }
}