/// <summary>
/// Receive the message from the socket pooling service.
/// </summary>
/// <param name="socket">Socket.</param>
/// <param name="size">Size of the message.</param>
/// <returns>Message received.</returns>
internal static unsafe SockPoolMessage ReceiveMessage(
Socket socket,
int size)
{
var buffer = new byte[size];
fixed(byte *bufferPtr = &buffer[0])
{
var data = new[]
{
new Iovec
{
iov_base = (IntPtr)bufferPtr,
iov_len = (ulong)buffer.Length
}
};
var controlBuffer = new byte[Syscall.CMSG_SPACE(sizeof(int))];
var message = new Msghdr
{
msg_iov = data,
msg_iovlen = data.Length,
msg_control = controlBuffer,
msg_controllen = controlBuffer.Length
};
Syscall.recvmsg(socket.Handle.ToInt32(), message, 0);
var result = new SockPoolMessage
{
Buffer = buffer
};
// Parse the control part of the message if exists. This may
// contain a socket handle
if (message.msg_controllen > 0)
{
var control = Cmsghdr.ReadFromBuffer(message, 0);
var offset = (int)Syscall.CMSG_DATA(message, 0);
result.Handle =
new IntPtr(BitConverter.ToInt32(controlBuffer, offset)
);
}
return(result);
}
}
/// <summary>
/// Send the message to the socket pooling service.
/// </summary>
/// <param name="socket">Socket.</param>
/// <param name="message">Message.</param>
internal static unsafe void SendMessage(
Socket socket,
SockPoolMessage message)
{
fixed(byte *bufferPtr = &message.Buffer[0])
{
var data = new[]
{
new Iovec
{
iov_base = (IntPtr)bufferPtr,
iov_len = (ulong)message.Buffer.Length
}
};
var msghdr = new Msghdr
{
msg_iovlen = data.Length,
msg_iov = data
};
if (message.Handle != IntPtr.Zero)
{
msghdr.msg_control = new byte[Syscall.CMSG_SPACE(sizeof(int))];
var control = new Cmsghdr();
control.cmsg_len = msghdr.msg_controllen
= msghdr.msg_control.Length;
control.cmsg_level = UnixSocketProtocol.SOL_SOCKET;
control.cmsg_type = UnixSocketControlMessage.SCM_RIGHTS;
control.WriteToBuffer(msghdr, 0);
var handleBuffer
= BitConverter.GetBytes(message.Handle.ToInt32());
Buffer.BlockCopy(
handleBuffer,
0,
msghdr.msg_control,
(int)Syscall.CMSG_SPACE(0),
sizeof(int)
);
}
var rc = -1L;
do
{
rc = Syscall.sendmsg(socket.Handle.ToInt32(), msghdr, 0);
if (rc == -1)
{
throw new Exception(
"Failed to send a message to the sockpool socket" +
$", rc={Syscall.GetLastError()}"
);
}
else if (rc > 0)
{
data[0].iov_base += (int)rc;
data[0].iov_len -= (ulong)rc;
// Reach the end of the buffer
if (data[0].iov_len == 0)
{
break;
}
}
}while(rc != 0);
}
}
