iocp openssl peer server 与 ConnectEx 连接后关闭连接

Question

I have problems making openssl working with iocp on windows , currently trying client mode only

I could make async write and read using the memory bios but but I'm struggling to get the async connect and handshake work

if I connect using SSL_connect then do the handshake using SSL_do_handshake then replace the bios with memory bios I can read and write async well

in async connect I do the following :

• issue a connection with ConnectEx
• handle the result with iocp
• call SSL_do_handshake and retrieve the result
• check if there is error if SSL_WANT_READ or SSL_WANT_WRITE and I always get the former
• I then try to receive some data into the in bio (tried async and sync) but here the failure . I tried using recv and complete the handshake sync but recv returned 0 . also tried WSARecv but in the completion notification I get 0 bytes transferred so I end the connection

this is some related code I'm using :

class AsyncSSLSocket;
using SSLOnConnect = std::function<void(AsyncSSLSocket&, std::error_code, SockAddr&)>;

struct SSLConnectCtx : public io::BaseIoCtx
{
    AsyncSSLSocket *sslsock;
    std::variant<IpV4Addr, IpV6Addr> addr;
    SSLOnConnect OnConnect;

    virtual void HandleIocpPacket(io::iocp::CompletionResult& IocpPacket) override;

    void CompleteHandShake();

};

inline void SSLConnectCtx::HandleIocpPacket(io::iocp::CompletionResult& IocpPacket)
{

    DWORD Transferred, RecvFlags;
    WSAGetOverlappedResult(sock->GetHandle().get(), reinterpret_cast<LPWSAOVERLAPPED>(IocpPacket.Ctx), &Transferred, 0, &RecvFlags);
    auto error = sock->LastError(); // WSAGetLastError()

    if (!error)
    {
        IocpPacket.Ctx = nullptr;
        sslsock->sslhandle.SetClientMode(); // SSL_set_connect_state
        CompleteHandShake();
        return;
    }

    auto& peer_addr = ExtractAddr(addr);
    OnConnect(*sslsock, error, peer_addr);
}

inline void SSLConnectCtx::CompleteHandShake()
{
    auto& sslhandle = sslsock->sslhandle;
    int ret = sslhandle.DoHandShake(); // SSL_do_handshake
    std::error_code error;

    if (ret < 0)
    {
        error = sslhandle.LastError(ret);

        if (sslhandle.WantRead(error.value())) // always get here
        {
            error = sslsock->FillInBIO([this](auto&, auto error, uint32_t trans)
            {
                MakeErrorIfZeroIsRecved(trans, error); // set error to std::errc::connection_abort (106) if WSARecv received 0 bytes
                if (!error)
                {
                    CompleteHandShake();
                    return;
                }
                // always get here 
                // prints : [!] failed to get data for the handshake !, error : generic:106 ==> connection aborted
                std::cout << "[!] failed to get data for the handshake !, error : " << error << " ==> " << error.message() << std::endl;
                OnConnect(*sslsock, error, ExtractAddr(addr));
                delete this;
            });
            if (!error)
                return;
        }

        else if (sslhandle.WantWrite(error.value()))
        {
            error = sslsock->FlushOutBIO([this](auto&, auto error, uint32_t) 
            {
                if (!error)
                {
                    CompleteHandShake();
                    return;
                }
                OnConnect(*sslsock, error, ExtractAddr(addr));
                delete this;
            });
            if (!error)
                return;
        }
    }

    OnConnect(*sslsock, error, ExtractAddr(addr));
    delete this;
}

void AsyncSSLSocket::AsyncConnect(SockAddr& addr, const SSLOnConnect& OnConnect)
    {
        SSLConnectCtx * ctx{ new SSLConnectCtx{} };
        ctx->sslsock = this;
        ctx->sock = &sock;
        SetAddrs(ctx->addr, addr);
        ctx->OnConnect = OnConnect;

        auto result = sock.AsyncConnect(addr, *ctx);
        if (result)
            return;
        delete ctx;
        OnConnect(*this, sock.LastError(), addr);
    }

    std::error_code AsyncSSLSocket::FillInBIO(SSLOnRead&& OnRead)
    {
        char *buff = new char[1024];
        CachedReadBuff = io::IoBuffer(buff, 1024);
        CachedOnRead = std::move(OnRead);

        SockRecvCtx * ctx{ new SockRecvCtx{} };
        ctx->sock = &sock;
        ctx->OnRecv = [this](Socket&, std::error_code error, uint32_t transferred)
        {
            MakeErrorIfZeroIsRecved(transferred, error);
            if (!error)
                inBIO.Write(CachedReadBuff.data(), static_cast<int>(transferred));              
            delete CachedReadBuff.data();
            CachedOnRead(*this, error, transferred);
        };

        auto result = sock.AsyncRecv(CachedReadBuff, *ctx);
        if (result)
            return std::error_code{};
        delete ctx;
        return result.error;
    }

Answer 1

it seems that SSL_do_handshake put some data in the out bio and returned SSL_get_error returned SSL_ERROR_WANT_READ so I went to read more data from the server while the server was waiting to receive some data from the client , so WSARecv or recv waits for some seconds ( maybe the server has timeout ?) until the server closes the connection and I get 0 bytes received .

so I used this code :

inline void SSLConnectCtx::CompleteHandShake()
{
    auto& sslhandle = sslsock->sslhandle;
    int ret = sslhandle.DoHandShake(); // SSL_do_handshake
    std::error_code error;

    if (ret < 0)
    {

        int pending = sslsock->outBIO.Pending();
        if (pending > 0)
        {
            std::cout << "[!!!] there is some data to send !" << std::endl;
            error = sslsock->FlushOutBIO([this](auto&, auto error, uint32_t)
            {
                if (!error)
                {
                    CompleteHandShake();
                    return;
                }
                OnConnect(*sslsock, error, ExtractAddr(addr));
                delete this;
            });
            if (!error)
                return;
            std::cout << "[!] failed to flush ! , error " << error << " ==> " << error.message() << std::endl;
        }

        error = sslhandle.LastError(ret);

        if (sslhandle.WantRead(error.value())) // always get here
        {
            std::cout << "[!!!] needs to read in the bio" << std::endl;
            error = sslsock->FillInBIO([this](auto&, auto error, uint32_t trans)
            {
                MakeErrorIfZeroIsRecved(trans, error); // set error to std::errc::connection_abort (106) if WSARecv received 0 bytes
                if (!error)
                {
                    CompleteHandShake();
                    return;
                }
                // always get here 
                // prints : [!] failed to get data for the handshake !, error : generic:106 ==> connection aborted
                std::cout << "[!] failed to get data for the handshake !, error : " << error << " ==> " << error.message() << std::endl;
                OnConnect(*sslsock, error, ExtractAddr(addr));
                delete this;
            });
            if (!error)
                return;
        }

        else if (sslhandle.WantWrite(error.value()))
        {
            error = sslsock->FlushOutBIO([this](auto&, auto error, uint32_t) 
            {
                if (!error)
                {
                    CompleteHandShake();
                    return;
                }
                OnConnect(*sslsock, error, ExtractAddr(addr));
                delete this;
            });
            if (!error)
                return;
        }
    }

    OnConnect(*sslsock, error, ExtractAddr(addr));
    delete this;
}

but now how the error was SSL_ERROR_WANT_READ while there is a need to write before read !

I read that there may be a re-negotiation at any point during the communication so if SSL_write returned SSL_ERROR_WANT_READ should I begin to read or send pending data ? also if SSL_read returned SSL_ERROR_WANT_WRITE should I begin to send data or receive data ?