코드 3-4 SocketAddressFactory를 써서 네임 리졸루션하기

class SocketAddressFactory
{
public:
    static SocketAddressPtr CreateIPv4FromString(const string& inString)
    {
        auto pos = inString.find_last_of(‘:’);
        string host, service;
        if (pos != string::npos)
        {
            host = inString.substr(0, pos);
            service = inString.substr(pos + 1);
        }
        else
        {
            // 포트가 지정되지 않았으므로 디폴트를 사용함
            host = inString;
            service = “0”;
        }
        addrinfo hint;
        memset(&hint, 0, sizeof(hint));
        hint.ai_family = AF_INET;
 
        addrinfo* result = nullptr;
        int error = getaddrinfo(host.c_str(), service.c_str(),
            &hint, &result);
        addrinfo* initResult = result;
 
        if (error != 0 && result != nullptr)
        {
            freeaddrinfo(initResult);
            return nullptr;
        }
 
        while (!result->ai_addr && result->ai_next)
        {
            result = result->ai_next;
        }
 
        if (!result->ai_addr)
        {
            freeaddrinfo(initResult);
            return nullptr;
        }
 
        auto toRet = std::make_shared<SocketAddress>(*result->ai_addr);
 
        freeaddrinfo(initResult);
        return toRet;
    }
};