Chapter 4. Internal Data Structures

Table of Contents

Xtransport

XtransConnInfo

There are two major data structures associated with the transport independent portion of this interface. Additional data structures may be used internally by each transport.

Xtransport

Each transport supported has an entry in the transport table. The transport table is an array of Xtransport records. Each record contains all the entry points for a single transport. This record is defined as:

typedef struct _Xtransport {

    char *TransName;
    int  flags;

    XtransConnInfo (*OpenCOTSClient)(
    struct _Xtransport *,     /* transport */
    char     *,     /* protocol */
    char     *,     /* host */
    char     *      /* port */
    );

    XtransConnInfo (*OpenCOTSServer)(
    struct _Xtransport *,     /* transport */
    char *,     /* protocol */
    char *,     /* host */
    char *      /* port */
    );

    XtransConnInfo (*OpenCLTSClient)(
    struct _Xtransport *,     /* transport */
    char *,               /* protocol */
    char *,               /* host */
    char *               /* port */
    );

    XtransConnInfo (*OpenCLTSServer)(
     struct _Xtransport *,   /* transport */
     char *,     /* protocol */
     char *,     /* host */
     char *     /* port */
    );

    int     (*SetOption)(
     XtransConnInfo,          /* connection */
     int,               /* option */
     int               /* arg */
    );

    int     (*CreateListener)(
     XtransConnInfo,          /* connection */
     char *,               /* port */
     int               /* flags */
    );

    int     (*ResetListener)(
     XtransConnInfo          /* connection */
    );

    XtransConnInfo (*Accept)(
     XtransConnInfo          /* connection */
    );

    int     (*Connect)(
     XtransConnInfo,          /* connection */
     char *,               /* host */
     char *               /* port */
    );

    int     (*BytesReadable)(
     XtransConnInfo,          /* connection */
     BytesReadable_t *     /* pend */
    );

    int     (*Read)(
     XtransConnInfo,          /* connection */
     char *,               /* buf */
     int               /* size */
    );

    int     (*Write)(
     XtransConnInfo,          /* connection */
     char *,               /* buf */
     int               /* size */
    );

    int     (*Readv)(
     XtransConnInfo,          /* connection */
     struct iovec *,          /* buf */
     int               /* size */
    );

    int     (*Writev)(
     XtransConnInfo,          /* connection */
     struct iovec *,          /* buf */
     int               /* size */
    );

    int     (*Disconnect)(
     XtransConnInfo          /* connection */
    );

    int     (*Close)(
     XtransConnInfo          /* connection */
    );

} Xtransport;

typedef struct _Xtransport {

    char *TransName;
    int  flags;

    XtransConnInfo (*OpenCOTSClient)(
    struct _Xtransport *,     /* transport */
    char     *,     /* protocol */
    char     *,     /* host */
    char     *      /* port */
    );

    XtransConnInfo (*OpenCOTSServer)(
    struct _Xtransport *,     /* transport */
    char *,     /* protocol */
    char *,     /* host */
    char *      /* port */
    );

    XtransConnInfo (*OpenCLTSClient)(
    struct _Xtransport *,     /* transport */
    char *,               /* protocol */
    char *,               /* host */
    char *               /* port */
    );

    XtransConnInfo (*OpenCLTSServer)(
     struct _Xtransport *,   /* transport */
     char *,     /* protocol */
     char *,     /* host */
     char *     /* port */
    );

    int     (*SetOption)(
     XtransConnInfo,          /* connection */
     int,               /* option */
     int               /* arg */
    );

    int     (*CreateListener)(
     XtransConnInfo,          /* connection */
     char *,               /* port */
     int               /* flags */
    );

    int     (*ResetListener)(
     XtransConnInfo          /* connection */
    );

    XtransConnInfo (*Accept)(
     XtransConnInfo          /* connection */
    );

    int     (*Connect)(
     XtransConnInfo,          /* connection */
     char *,               /* host */
     char *               /* port */
    );

    int     (*BytesReadable)(
     XtransConnInfo,          /* connection */
     BytesReadable_t *     /* pend */
    );

    int     (*Read)(
     XtransConnInfo,          /* connection */
     char *,               /* buf */
     int               /* size */
    );

    int     (*Write)(
     XtransConnInfo,          /* connection */
     char *,               /* buf */
     int               /* size */
    );

    int     (*Readv)(
     XtransConnInfo,          /* connection */
     struct iovec *,          /* buf */
     int               /* size */
    );

    int     (*Writev)(
     XtransConnInfo,          /* connection */
     struct iovec *,          /* buf */
     int               /* size */
    );

    int     (*Disconnect)(
     XtransConnInfo          /* connection */
    );

    int     (*Close)(
     XtransConnInfo          /* connection */
    );

} Xtransport;

The flags field can contain an OR of the following masks:

TRANS_ALIAS	indicates that this record is providing an alias, and should not be used to create a listener.
TRANS_LOCAL	indicates that this is a LOCALCONN transport.
TRANS_ABSTRACT	indicates that a local connection transport uses the abstract socket namespace.

Some additional flags may be set in the flags field by the library while it is running:

TRANS_DISABLED	indicates that this transport has been disabled.
TRANS_NOLISTEN	indicates that servers should not open new listeners using this transport.
TRANS_NOUNLINK	set by a transport backend to indicate that the endpoints for its connection should not be unlinked.

XtransConnInfo

Each connection will have an opaque XtransConnInfo transport connection object allocated for it. This record contains information specific to the connection. The record is defined as:

typedef struct _XtransConnInfo *XtransConnInfo;

struct _XtransConnInfo {
    struct _Xtransport     *transptr;
    char     *priv;
    int          flags;
    int          fd;
    int          family;
    char     *addr;
    int          addrlen;
    char     *peeraddr;
    int          peeraddrlen;
};

typedef struct _XtransConnInfo *XtransConnInfo;

struct _XtransConnInfo {
    struct _Xtransport     *transptr;
    char     *priv;
    int          flags;
    int          fd;
    int          family;
    char     *addr;
    int          addrlen;
    char     *peeraddr;
    int          peeraddrlen;
};