[Vm-dev] is it possible access OS socket handler from Socket instance

[Denis Kudriashov]

Thank's Eliot for such detailed response.

First case should be really fun. I like hacking :). Then I will look at
primitive.

Best regards,
Denis

2017-08-08 20:34 GMT+02:00 Eliot Miranda <eliot.miranda at gmail.com>:

>
> Hi Denis,
>
> On Tue, Aug 8, 2017 at 2:11 AM, Denis Kudriashov <dionisiydk at gmail.com>
> wrote:
>
>>
>> Hi.
>>
>> I play a bit of idea to make binding to libssh2 library.
>>
>> And the main problem is function
>>
>> int libssh2_session_handshake(LIBSSH2_SESSION *session, libssh2_socket_t
>> socket)
>>
>> where socket parameter is raw OS socket handle as I understand.
>>
>> So question: is it possible to access this handle from image side from
>> Socket instance?
>>
>
> Yes, but non-trivially.
>
>
>> There is socketHandle instance variable which is bytearray. What is it?
>>
>
> It is an instance of this struct:
>
> typedef struct
> {
>   int   sessionID;
>   int   socketType;  /* 0 = TCP, 1 = UDP */
>   void  *privateSocketPtr;
> }  SQSocket, *SocketPtr;
>
> The two most common definitions are:
> linux/mac
> typedef struct privateSocketStruct
> {
>   int s;            /* Unix socket */
>   int connSema;         /* connection io notification semaphore */
>   int readSema;         /* read io notification semaphore */
>   int writeSema;        /* write io notification semaphore */
>   int sockState;        /* connection + data state */
>   int sockError;        /* errno after socket error */
>   union sockaddr_any peer;  /* default send/recv address for UDP */
>   socklen_t peerSize;       /* dynamic sizeof(peer) */
>   union sockaddr_any sender;    /* sender address for last UDP receive */
>   socklen_t senderSize;     /* dynamic sizeof(sender) */
>   int multiListen;      /* whether to listen for multiple connections */
>   int acceptedSock;     /* a connection that has been accepted */
> } privateSocketStruct;
>
> win32:
> typedef struct privateSocketStruct {
>   struct privateSocketStruct *next;
>   SOCKET s;
>
>   int sockType;
>   int sockState;
>   int sockError;
>
>   int readSema;
>   int writeSema;
>   int connSema;
>
>   union sockaddr_any peer;  /* socket address in connect() or send/rcv
> address for UDP */
>   socklen_t peerSize;       /* dynamic sizeof(peer) */
>
>   HANDLE mutex;             /* The mutex used for synchronized access to
> this socket */
>   acceptedSocketStruct *accepted; /* Accepted connections on a socket */
>
>
>   DWORD  readWatcherOp;      /* read operation to watch */
>   HANDLE hReadWatcherEvent;  /* event for waking up read watcher */
>   HANDLE hReadThread;
>
>   DWORD  writeWatcherOp;     /* write operation to watch */
>   HANDLE hWriteWatcherEvent; /* event for waking up write watcher */
>   HANDLE hWriteThread;
>
>   volatile DWORD closePending; /* Cleanup counter */
>
>   int readSelect;
>   int writeSelect;
> } privateSocketStruct;
>
> So you *could* create an Alien on the 4 bytes at 9 in the handle on
> 32-bits, or the 8 bytes at 9 on 64-bits, and then decode the resulting
> pointer to a privateSocketStruct.  On linux & mac os it is the 4 bytes at
> 1.  On Win32 it's the 4 bytes at 5, and on Win64 it's the 4 bytes at 9.
>
> But I would instead add a new primitive to the socket plugin, something
> like primitiveSocketGetNativeHandle, and use that :-)
>
> To do this:
> a) modify VMMaker.oscog's SocketPlugin to add the primitive
> b) in platforms/Cross/plugins/SocketPlugin./SocketPlugin.h add something
> like
>     sqInt sqSocketNativeHandle(SocketPtr s, int type);
> where type is, say, 0 for the normal file descriptor and other values for
> future use (one platform has both data and control sockets in its
> privateSocketStruct
> c) implement sqSocketNativeHandle appropriately in platforms/unix/plugins/SocketPlugin/sqUnixSocket.c,
> platforms/win32/plugins/SocketPlugin/sqWin32NewNet.c et al. There are 5
> in all; Mac OS Carbon, RiscOS & Plan9 are the other three.)
>
> Best regards,
>> Denis
>>
>
> _,,,^..^,,,_
> best, Eliot
>
>
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