#ifndef CONNECT___NCBI_SOCKET__H
#define CONNECT___NCBI_SOCKET__H

/*  $Id: ncbi_socket.h,v 6.50 2004/07/23 19:04:38 lavr Exp $
 * ===========================================================================
 *
 *                            PUBLIC DOMAIN NOTICE
 *               National Center for Biotechnology Information
 *
 *  This software/database is a "United States Government Work" under the
 *  terms of the United States Copyright Act.  It was written as part of
 *  the author's official duties as a United States Government employee and
 *  thus cannot be copyrighted.  This software/database is freely available
 *  to the public for use. The National Library of Medicine and the U.S.
 *  Government have not placed any restriction on its use or reproduction.
 *
 *  Although all reasonable efforts have been taken to ensure the accuracy
 *  and reliability of the software and data, the NLM and the U.S.
 *  Government do not and cannot warrant the performance or results that
 *  may be obtained by using this software or data. The NLM and the U.S.
 *  Government disclaim all warranties, express or implied, including
 *  warranties of performance, merchantability or fitness for any particular
 *  purpose.
 *
 *  Please cite the author in any work or product based on this material.
 *
 * ===========================================================================
 *
 * Author:  Denis Vakatov
 *
 * File Description:
 *   Plain portable TCP/IP socket API for:  UNIX, MS-Win, MacOS
 *   Platform-specific library requirements:
 *     [UNIX ]   -DNCBI_OS_UNIX     -lresolv -lsocket -lnsl
 *     [MSWIN]   -DNCBI_OS_MSWIN    wsock32.lib
 *     [MacOS]   -DNCBI_OS_MAC      NCSASOCK -- BSD-style socket emulation lib
 *
 *********************************
 * Generic:
 *
 *  SOCK, LSOCK
 *
 *  SOCK_AllowSigPipeAPI
 *
 *  SOCK_InitializeAPI
 *  SOCK_ShutdownAPI
 *
 * Listening socket (handle LSOCK):
 *
 *  LSOCK_Create
 *  LSOCK_Accept
 *  LSOCK_Close
 *  
 * I/O Socket (handle SOCK):
 *
 *  SOCK_Create[Ex]      (see also LSOCK_Accept)
 *  SOCK_CreateOnTop[Ex]
 *  SOCK_Reconnect
 *  SOCK_Shutdown
 *  SOCK_Close
 *  SOCK_Wait
 *  SOCK_Poll
 *  SOCK_SetTimeout
 *  SOCK_GetReadTimeout
 *  SOCK_GetWriteTimeout
 *  SOCK_Read (including "peek" and "persistent read")
 *  SOCK_PushBack
 *  SOCK_Status
 *  SOCK_Write
 *  SOCK_Abort
 *  SOCK_GetPeerAddress
 *  SOCK_GetPeerAddressString
 *
 *  SOCK_SetReadOnWriteAPI
 *  SOCK_SetReadOnWrite
 *  SOCK_SetInterruptOnSignalAPI
 *  SOCK_SetInterruptOnSignal
 *  SOCK_SetReuseAddressAPI
 *  SOCK_SetReuseAddress
 *
 * Datagram Socket:
 *
 *  DSOCK_Create[Ex]
 *  DSOCK_Bind
 *  DSOCK_Connect
 *  DSOCK_WaitMsg
 *  DSOCK_SendMsg
 *  DSOCK_RecvMsg
 *  DSOCK_WipeMsg
 *  DSOCK_SetBroadcast
 *
 * Socket classification:
 *
 *  SOCK_IsDatagram
 *  SOCK_IsClientSide
 *  SOCK_IsServerSide
 *
 * Data logging:
 *
 *  SOCK_SetDataLoggingAPI
 *  SOCK_SetDataLogging
 *
 * Auxiliary:
 *
 *  SOCK_gethostname
 *  SOCK_ntoa
 *  SOCK_HostToNetShort
 *  SOCK_HostToNetLong
 *  SOCK_NetToHostShort
 *  SOCK_NetToHostLong
 *  SOCK_gethostbyname
 *  SOCK_gethostbyaddr
 *
 */

#if defined(NCBISOCK__H)
#  error "<ncbisock.h> and <ncbi_socket.h> must never be #include'd together"
#endif

#include <connect/ncbi_core.h>


/** @addtogroup Sockets
 *
 * @{
 */


#ifdef __cplusplus
extern "C" {
#endif


/******************************************************************************
 *  TYPEDEFS & MACROS
 */


/* Network and host byte order enumeration type
 */
typedef enum {
    eNH_HostByteOrder,
    eNH_NetworkByteOrder
} ENH_ByteOrder;


/* Forward declarations of the hidden socket internal structure, and
 * their upper-level handles to use by the LSOCK_*() and SOCK_*() API
 */
struct LSOCK_tag;                /* listening socket:  internal storage */
typedef struct LSOCK_tag* LSOCK; /* listening socket:  handle           */

struct SOCK_tag;                 /* socket:  internal storage           */
typedef struct SOCK_tag*  SOCK;  /* socket:  handle                     */



/******************************************************************************
 *  Multi-Thread safety
 *
 * If you are using this API in a multi-thread application, and there is
 * more than one thread using this API, it is safe to call SOCK_InitializeAPI()
 * explicitly in the beginning of your main thread, before you run any other
 * threads, and to call SOCK_ShutdownAPI() after all threads are exited.
 *
 * As soon as the API is initialized it becomes relatively MT-safe, however
 * you still must not operate with the same LSOCK or SOCK objects from
 * different threads simultaneously.
 *
 * A MUCH BETTER WAY of dealing with this issue is to provide your own MT
 * locking callback (see CORE_SetLOCK in "ncbi_core.h"). This will also
 * guarantee the proper MT protection should some other SOCK functions
 * start to access any static data in the future.
 */



/******************************************************************************
 *   Error & Data Logging
 *
 * NOTE:  Use CORE_SetLOG() from "ncbi_core.h" to setup the log handler.
 */


/* By default ("log" == eDefault, which is eOff), the data is not logged.
 * To start logging the data, call this func with "log" == eOn.
 * To stop  logging the data, call this func with "log" == eOff.
 * Return prior setting.
 */
extern NCBI_XCONNECT_EXPORT ESwitch SOCK_SetDataLoggingAPI
(ESwitch log
 );


/* Control the data logging for socket "sock" individually.
 * To reset to the global default behavior (as set by SOCK_SetDataLoggingAPI),
 * call this function with "log" == eDefault.
 * Return prior setting.
 */
extern NCBI_XCONNECT_EXPORT ESwitch SOCK_SetDataLogging
(SOCK    sock,
 ESwitch log
 );



/******************************************************************************
 *   I/O restart on signals
 */


/* By default ("on_off" == eDefault,eOff), I/O is restartable if interrupted.
 * Return prior setting.
 */
extern NCBI_XCONNECT_EXPORT ESwitch SOCK_SetInterruptOnSignalAPI
(ESwitch on_off
 );


/* Control sockets individually. eDefault causes the use of global API flag.
 * Return prior setting.
 */
extern NCBI_XCONNECT_EXPORT ESwitch SOCK_SetInterruptOnSignal
(SOCK    sock,
 ESwitch on_off
 );



/******************************************************************************
 *   Address reuse: EXPERIMENTAL and may be removed in the upcoming releases!
 */


/* By default ("on_off" == eDefault,eOff), address is not marked for reuse
 * in SOCK, but is always reused for LSOCK.
 * Return prior setting.
 */
extern NCBI_XCONNECT_EXPORT ESwitch SOCK_SetReuseAddressAPI
(ESwitch on_off
 );


/* Control sockets individually (Note: only boolean value is available here.)
 * No return value is available.
 */
extern NCBI_XCONNECT_EXPORT void SOCK_SetReuseAddress
(SOCK        sock,
 int/*bool*/ on_off);



/******************************************************************************
 *  API Initialization and Shutdown/Cleanup
 */


/*
 */
extern NCBI_XCONNECT_EXPORT const STimeout*SOCK_SetSelectInternalRestartTimeout
(const STimeout* timeout);


/* By default (on UNIX platforms) the SOCK API functions automagically call
 * "signal(SIGPIPE, SIG_IGN)" on initialization.  To prohibit this feature,
 * you must call SOCK_AllowSigPipeAPI() before you call any other
 * function from the SOCK API.
 */
extern NCBI_XCONNECT_EXPORT void SOCK_AllowSigPipeAPI(void);


/* Initialize all internal/system data & resources to be used by the SOCK API.
 * NOTE:
 *  You can safely call it more than once; just, all calls after the first
 *  one will have no result. 
 * NOTE:
 *  Usually, SOCK API does not require an explicit initialization -- as it is
 *  guaranteed to initialize itself automagically, in one of API functions,
 *  when necessary. Yet, see the "Multi Thread safety" remark above.
 * NOTE:
 *  This call, when used for the very first time in the application, enqueues
 *  SOCK_ShutdownAPI() to be called upon application exit on plaftorms that
 *  provide this functionality. In any case, the application can opt for
 *  explicit SOCK_ShutdownAPI() call when it is done with all sockets.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_InitializeAPI(void);


/* Cleanup; destroy all internal/system data & resources used by the SOCK API.
 * ATTENTION:  no function from the SOCK API should be called after this call!
 * NOTE: you can safely call it more than once; just, all calls after the first
 *       one will have no result. 
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_ShutdownAPI(void);



/******************************************************************************
 *  LISTENING SOCKET
 */

typedef enum {
    fLSCE_LogOff     = eOff,      /* logging is inherited in Accept()ed SOCKs*/
    fLSCE_LogOn      = eOn,       /*                    -"-                  */
    fLSCE_LogDefault = eDefault,  /*                    -"-                  */
    fLSCE_BindAny    = 0,         /* bind to 0.0.0.0, default                */
    fLSCE_BindLocal  = 0x10       /* bind to 127.0.0.1 only                  */
} FLSCE_Flags;
typedef unsigned int TLSCE_Flags;

/* [SERVER-side]  Create and initialize the server-side(listening) socket
 * (socket() + bind() + listen())
 * NOTE: on some systems, "backlog" can be silently limited down to 128 (or 5).
 */
extern NCBI_XCONNECT_EXPORT EIO_Status LSOCK_CreateEx
(unsigned short port,    /* [in]  the port to listen at                  */
 unsigned short backlog, /* [in]  maximal # of pending connections       */
 LSOCK*         lsock,   /* [out] handle of the created listening socket */
 TLSCE_Flags    flags    /* [in]  special modifiers                      */
 );

extern NCBI_XCONNECT_EXPORT EIO_Status LSOCK_Create
(unsigned short port,    /* [in]  the port to listen at                  */
 unsigned short backlog, /* [in]  maximal # of pending connections       */
 LSOCK*         lsock    /* [out] handle of the created listening socket */
 );


/* [SERVER-side]  Accept connection from a client.
 * NOTE: the "*timeout" is for this accept() only.  To set I/O timeout,
 *       use SOCK_SetTimeout();  all I/O timeouts are infinite by default.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status LSOCK_Accept
(LSOCK           lsock,    /* [in]  handle of a listening socket */
 const STimeout* timeout,  /* [in]  timeout (infinite if NULL)   */
 SOCK*           sock      /* [out] handle of the created socket */
 );


/* [SERVER-side]  Close the listening socket, destroy relevant internal data.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status LSOCK_Close(LSOCK lsock);


/* Get an OS-dependent native socket handle to use by platform-specific API.
 * FYI:  on MS-Windows it will be "SOCKET", on other platforms -- "int".
 */
extern NCBI_XCONNECT_EXPORT EIO_Status LSOCK_GetOSHandle
(LSOCK  lsock,
 void*  handle_buf,  /* pointer to a memory area to put the OS handle at */
 size_t handle_size  /* the exact(!) size of the expected OS handle */
 );



/******************************************************************************
 *  SOCKET
 */


/* [CLIENT-side]  Connect client to another(server-side, listening) socket
 * (socket() + connect() [+ select()])
 */
/* SOCK_CreateEx(host, port, timeout, sock, 0, 0, eDefault) */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Create
(const char*     host,    /* [in]  host to connect to                        */
 unsigned short  port,    /* [in]  port to connect to                        */
 const STimeout* timeout, /* [in]  the connect timeout (infinite if NULL)    */
 SOCK*           sock     /* [out] handle of the created socket              */
 );

extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_CreateEx
(const char*     host,     /* [in]  host to connect to                       */
 unsigned short  port,     /* [in]  port to connect to                       */
 const STimeout* timeout,  /* [in]  the connect timeout (infinite if NULL)   */
 SOCK*           sock,     /* [out] handle of the created socket             */
 const void*     init_data,/* [in]  initial output data segment (may be NULL)*/
 size_t          init_size,/* [in]  size of initial data segment (may be 0)  */
 ESwitch         log       /* [in]  whether to do logging on this socket     */
 );


/* [SERVER-side]  Create a socket on top of OS-dependent "handle"
 * (file descriptor on Unix). Returned socket is not reopenable to its
 * default peer (SOCK_Reconnect may not specify zeros for the connection
 * point).  All timeouts are set to its default [infinite] values.
 * SOCK_Close() will close the "handle" only if the "close_on_close"
 * parameter is passed non-zero (eSCOT_CloseOnClose).
 * Return eIO_Success on success; otherwise: eIO_Closed if the "handle" does
 * not refer to an open socket [but e.g. to a normal file or a pipe];
 * other error codes in case of other errors.
 */
typedef enum {
    eSCOT_KeepOnClose,    /* Do not close "handle" on SOCK_Close() */
    eSCOT_CloseOnClose    /* Do close "handle" on SOCK_Close() */
} ESCOT_OnClose;

/* SOCK_CreateOnTopEx(handle, handle_size, sock,
                      0, 0, eDefault, eSCOT_CloseOnClose) */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_CreateOnTop
(const void*   handle,      /* [in]  OS-dependent "handle" to be converted */
 size_t        handle_size, /* [in]  "handle" size                         */
 SOCK*         sock         /* [out] SOCK built on top of OS "handle"      */
 );

extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_CreateOnTopEx
(const void*   handle,      /* [in]  OS-dependent "handle" to be converted */
 size_t        handle_size, /* [in]  "handle" size                         */
 SOCK*         sock,        /* [out] SOCK built on top of OS "handle"      */
 const void*   init_data,   /* [in]  initial output data segment (ok NULL) */
 size_t        init_size,   /* [in]  size of initial data segment (ok 0)   */
 ESwitch       log,         /* [in]  data logging for the resulting SOCK   */
 ESCOT_OnClose on_close     /* [in]  if to keep "handle" in SOCK_Close()   */
 );


/* [CLIENT-side]  Close the socket referred to by "sock" and then connect
 * it to another "host:port";  fail if it takes more than "timeout"
 * (close() + connect() [+ select()])
 *
 * HINT:  if "host" is NULL then connect to the same host address as before;
 *        if "port" is zero then connect to the same port # as before.
 *
 * NOTE1: "new" socket inherits the old I/O timeouts.
 * NOTE2: the call is applicable to stream [not datagram] sockets only.
 * NOTE3: "timeout"==NULL is infinite; "timeout"=={0,0} causes no wait for
 *        connection to be established and to return immediately.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Reconnect
(SOCK            sock,    /* [in] handle of the socket to reconnect      */
 const char*     host,    /* [in] host to connect to  (can be NULL)      */
 unsigned short  port,    /* [in] port to connect to  (can be 0)         */
 const STimeout* timeout  /* [in] the connect timeout (infinite if NULL) */
 );


/* Shutdown the connection in only one direction (specified by "direction").
 * Later attempts to I/O (or to wait) in the shutdown direction will
 * do nothing, and immediately return with "eIO_Closed" status.
 * Pending data output can cause data transfer to the remote end (subject
 * for eIO_Close timeout as previously set by SOCK_SetTimeout()).
 * Cannot be applied to datagram sockets (eIO_InvalidArg results).
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Shutdown
(SOCK      sock, /* [in] handle of the socket to shutdown            */
 EIO_Event how   /* [in] one of:  eIO_Read, eIO_Write, eIO_ReadWrite */
 );


/* Close the connection, destroy relevant internal data.
 * The "sock" handle goes invalid after this function call, regardless
 * of whether the call was successful or not.
 * NOTE1:  if eIO_Close timeout was specified (or NULL) then it blocks until
 *         either all unsent data are sent, error flagged, or the timeout
 *         expires.
 * NOTE2:  if there is output pending, that output will be flushed.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Close(SOCK sock);


/* Close the connection, and conditionally destroy relevant internal data.
 * NOTE1:  if eIO_Close timeout was specified (or NULL) then it blocks until
 *         either all unsent data are sent, error flagged, or the timeout
 *         expires.
 * NOTE2:  if there is output pending, that output will be flushed.
 * NOTE3:  SOCK_CloseEx(sock, 1) is equivalent to SOCK_Close(sock);
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_CloseEx
(SOCK        sock,    /* [in] handle of the socket to close           */
 int/*bool*/ destroy  /* [in] =1 to destroy handle; =0 to keep handle */
 );


/* Block on the socket until either read/write (dep. on the "event" arg) is
 * available or timeout expires (if "timeout" is NULL then assume it infinite).
 * For a datagram socket, eIO_Closed is returned if the internally latched
 * message was entirely read out, and eIO_Read was requested as the "event".
 * Both eIO_Write and eIO_ReadWrite events always immediately succeed for
 * the datagram socket.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Wait
(SOCK            sock,
 EIO_Event       event,  /* [in] one of:  eIO_Read, eIO_Write, eIO_ReadWrite */
 const STimeout* timeout
 );


/* Block until at least one of the sockets enlisted in "polls" array
 * (of size "n") becomes available for requested operation (event),
 * or until timeout expires (wait indefinitely if timeout is passed NULL).
 * Return eIO_Success if at least one socket was found ready; eIO_Timeout
 * if timeout expired; eIO_Unknown if underlying system call(s) failed.
 * NOTE1: For a socket found not ready for an operation, eIO_Open is returned
 *        in its "revent"; for a failing socket, eIO_Close is returned;
 * NOTE2: This call may return eIO_InvalidArg if
 *        - parameters to the call are inconsistent;
 *        - a non-NULL socket polled with a bad "event" (eIO_Open, eIO_Close).
 *        With this return code, the calling program cannot rely on "revent"
 *        fields the "polls" array as they might not be properly updated.
 * NOTE3: If either both "n" and "polls" are NULL, or all sockets in "polls"
 *        are NULL, then the returned result is either
 *        eIO_Timeout (after the specified amount of time was spent idle), or
 *        eIO_Interrupted (if signal came while the waiting was in progress).
 * NOTE4: For datagram sockets, the readiness for reading is determined by
 *        message data latched since last message receive call (DSOCK_RecvMsg).
 * NOTE5: This call allows intermixture of stream and datagram sockets.
 * NOTE6: This call can cause some socket I/O in those sockets marked for
 *        read-on-write and those with pending connection or output data.
 */

typedef struct {
    SOCK      sock;   /* [in]           SOCK to poll (NULL if not to poll)   */
    EIO_Event event;  /* [in]  one of:  eIO_Read, eIO_Write, eIO_ReadWrite   */
    EIO_Event revent; /* [out] one of:  eIO_Open/Read/Write/ReadWrite/Close  */
} SSOCK_Poll;

extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Poll
(size_t          n,         /* [in]      # of SSOCK_Poll elems in "polls"    */
 SSOCK_Poll      polls[],   /* [in|out]  array of query/result structures    */
 const STimeout* timeout,   /* [in]      max time to wait (infinite if NULL) */
 size_t*         n_ready    /* [out]     # of ready sockets  (may be NULL)   */
 );



/* GENERIC POLLABLE INTERFACE, please see above for explanations
 */
struct SPOLLABLE_tag;
typedef struct SPOLLABLE_tag* POLLABLE;

typedef struct {
    POLLABLE  poll;
    EIO_Event event;
    EIO_Event revent;
} SPOLLABLE_Poll;

extern NCBI_XCONNECT_EXPORT EIO_Status POLLABLE_Poll
(size_t          n,
 SPOLLABLE_Poll  polls[],
 const STimeout* timeout,
 size_t*         n_ready
 );


/* Return 0 if conversion cannot be made; otherwise converted handle */
extern NCBI_XCONNECT_EXPORT POLLABLE POLLABLE_FromSOCK (SOCK);
extern NCBI_XCONNECT_EXPORT POLLABLE POLLABLE_FromLSOCK(LSOCK);
extern NCBI_XCONNECT_EXPORT SOCK     POLLABLE_ToSOCK   (POLLABLE);
extern NCBI_XCONNECT_EXPORT LSOCK    POLLABLE_ToLSOCK  (POLLABLE);


/* Specify timeout for the connection i/o (see SOCK_[Read|Write|Close] funcs).
 * If "timeout" is NULL then set the timeout to be infinite;
 * NOTE: the default timeout is infinite (wait "ad infinitum" on I/O).
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_SetTimeout
(SOCK            sock,
 EIO_Event       event,   /* [in]  one of:  eIO_[Read/Write/ReadWrite/Close] */
 const STimeout* timeout  /* [in]  new timeout value to set                  */
 );


/* Get the connection's i/o timeout (or NULL, if the timeout is infinite).
 * NOTE1:  the returned timeout is guaranteed to be pointing to a valid
 *         (and correct) structure in memory at least until the SOCK is closed
 *         or SOCK_SetTimeout is called for this "sock".
 * NOTE2:  eIO_ReadWrite timeout is the least of eIO_Read and eIO_Write ones.
 */
extern NCBI_XCONNECT_EXPORT const STimeout* SOCK_GetTimeout
(SOCK      sock,
 EIO_Event event  /* [in]  one of:  eIO_[Read/Write/Close] */
 );


/* Read/peek up to "size" bytes from "sock" to the mem.buffer pointed by "buf".
 * In "*n_read", return the number of successfully read bytes.
 * Read method "how" can be either of the following:
 * eIO_ReadPlain   -- read as many as "size" bytes and return (eIO_Success);
 *                    if no data are readily available then wait at most
 *                    read timeout and return (eIO_Timeout) if no data still
 *                    could be got; eIO_Success if some data were obtained.
 * eIO_ReadPeek    -- same as "eIO_ReadPlain" but do not extract the data from
 *                    the socket (so that the next read operation will see the
 *                    data again), with one important exception noted below.
 * eIO_ReadPersist -- read exactly "size" bytes and return eIO_Success; if less
 *                    data received then return an error condition (including
 *                    eIO_Timeout).
 *
 * If there is no data available to read (also, if eIO_ReadPersist and cannot
 * read exactly "size" bytes) and the timeout(see SOCK_SetTimeout) is expired
 * then return eIO_Timeout.
 *
 * Both eIO_ReadPlain and eIO_ReadPeek return eIO_Success iff some data have
 * been read (perhaps within the time allowance specified by eIO_Read timeout).
 * Both mothods return any other code when no data at all were available.
 * eIO_ReadPersist differs from the other two methods as it can return an
 * error condition even if some data were actually obtained from the socket.
 * Hence, as a rule of thumb, an application should always check the number
 * of read bytes BEFORE checking the return status, which merely advises
 * whether it is okay to read again.
 *
 * As a special case, "buf" may passed as NULL:
 *   eIO_ReadPeek      -- read up to "size" bytes and store them
 *                        in internal buffer;
 *   eIO_Read[Persist] -- discard up to "size" bytes from internal buffer
 *                        and socket (check "*n_read" to know how many).
 *
 * NOTE1: "Read" and "peek" methods differ:  if "read" is performed and not
 *        enough but some data available immediately from the internal buffer,
 *        then the call completes with eIO_Success status.  For "peek", if
 *        not all requested data were available, the real I/O occurs to pick up
 *        additional data (if any) from the system. Keep this difference in
 *        mind when programming loops that heavily use "peek"s without "read"s.
 * NOTE2: If on input "size" == 0, then "*n_read" is set to 0, and the
 *        return value can be either of eIO_Success, eIO_Closed or
 *        eIO_Unknown depending on connection status of the socket.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Read
(SOCK           sock,
 void*          buf,    /* [out] data buffer to read to          */
 size_t         size,   /* [in]  max # of bytes to read to "buf" */
 size_t*        n_read, /* [out] # of bytes read  (can be NULL)  */
 EIO_ReadMethod how     /* [in]  how to read the data            */
 );


/* Push the specified data back to the socket input queue (in the socket's
 * internal read buffer). These can be any data, not necessarily the data
 * previously read from the socket.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_PushBack
(SOCK        sock,
 const void* buf,  /* [in] data to push back to the socket's local buffer */
 size_t      size  /* [in] # of bytes (starting at "buf") to push back    */
 );


/* Return (for the specified "direction" [eIO_Open to check for closed sock]):
 *   eIO_Closed     -- if the connection was shutdown by SOCK_Shutdown(), or
 *                     (for "eIO_Read" only) if EOF was detected
 *                     if "direction"==eIO_Open, this code means socket closed
 *   eIO_Unknown    -- if an error was detected during the last I/O
 *   eIO_InvalidArg -- if "direction" is not one of:  Open, Read, Write
 *   eIO_Timeout    -- if the socket is not yet actually connected
 *   eIO_Success    -- otherwise (incl. eIO_Timeout on last I/O)
 *
 * NOTE:  The SOCK_Read() and SOCK_Wait(eIO_Read) will not return any error
 *        as long as there is any unread (buffered) data left.
 *        Thus, when you are "peeking" data instead of actually reading it,
 *        then this is the only "non-destructive" way to check whether EOF
 *        or an error has actually occurred on read.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Status
(SOCK      sock,
 EIO_Event direction  /* [in] one of:  eIO_Open, eIO_Read, eIO_Write */
 );


/* Write "size" bytes from buffer "buf" to "sock".
 * In "*n_written", return the number of bytes actually written.
 * eIO_WritePlain   --  write as many bytes as possible at once and return
 *                      immediately; if no bytes can be written then wait
 *                      at most WRITE timeout, try again and return.
 * eIO_WritePersist --  write all data (doing an internal retry loop
 *                      if necessary); if any single write attempt times out
 *                      or fails then stop writing and return (error code).
 * Return status: eIO_Success -- some bytes were written successfully  [Plain]
 *                            -- all bytes were written successfully [Persist]
 *                other code denotes an error, but some bytes might have
 *                been sent nevertheless (always check *n_written to know).
 *
 * NOTE1: With eIO_WritePlain the call returns eIO_Success iff some data
 *        were actually written to the socket. If no data could be written
 *        (and perhaps timeout expired) this call always returns an error.
 * NOTE2: eIO_WritePlain and eIO_WritePersist differs that the latter can
 *        flag an error condition even if some data were actually written
 *        (see "the rule of thumb" in the comments for SOCK_Read() above).
 * NOTE3: if "size"==0, return value can be eIO_Success if no pending data
 *        left in the socket, or eIO_Timeout if there are still data pending.
 *        In either case, "*n_written" is set to 0 on return.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Write
(SOCK            sock,
 const void*     buf,       /* [in]  data to write to the socket             */
 size_t          size,      /* [in]  # of bytes (starting at "buf") to write */
 size_t*         n_written, /* [out] # of written bytes (can be NULL)        */
 EIO_WriteMethod how        /* [in]  eIO_WritePlain | eIO_WritePersist       */
 );


/* If there is outstanding connection or output data pending, cancel it.
 * Mark the socket as if it has been shut down for both reading and writing.
 * Break actual connection if any was established.
 * Do not attempt to send anything upon SOCK_Close().
 * This call is available for stream sockets only.
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_Abort
(SOCK sock
 );


/* Get host and port of the socket's peer.
 * If "network_byte_order" is true(non-zero) then return the host/port in the
 * network byte order; otherwise return them in the local host byte order.
 */
extern NCBI_XCONNECT_EXPORT void SOCK_GetPeerAddress
(SOCK            sock,
 unsigned int*   host,                /* [out] the peer's host (can be NULL) */
 unsigned short* port,                /* [out] the peer's port (can be NULL) */
 ENH_ByteOrder   byte_order           /* [in]  host/port byte order          */
 );


/* Get textual representation of the socket's peer.
 * For INET domain sockets, the result is of the form "aaa.bbb.ccc.ddd:ppppp";
 * for UNIX domain socket, the result is the name of the socket's file.
 * On success, return its "buf" argument; return 0 on error.
 */
extern NCBI_XCONNECT_EXPORT char* SOCK_GetPeerAddressString
(SOCK   sock,
 char*  buf,        /* [out] pointer to provided buffer to store the text to */
 size_t buflen      /* [in]  usable size of the buffer above                 */
 );


/* Get an OS-dependent native socket handle to use by platform-specific API.
 * FYI:  on MS-Windows it will be "SOCKET", on other platforms -- "int".
 */
extern NCBI_XCONNECT_EXPORT EIO_Status SOCK_GetOSHandle
(SOCK   sock,
 void*  handle_buf,  /* pointer to a memory area to put the OS handle at */
 size_t handle_size  /* the exact(!) size of the expected OS handle      */
 );


/* By default ("on_off" == eDefault,eOff), sockets will not try to read data
 * from inside SOCK_Write(). If you want to automagically upread the data
 * (and cache it in the internal socket buffer) when the write operation
 * is not immediately available, call this func with "on_off" == eOn.
 * Return prior setting.
 */
extern NCBI_XCONNECT_EXPORT ESwitch SOCK_SetReadOnWriteAPI
(ESwitch on_off
 );


/* Control the reading-while-writing feature for socket "sock" individually.
 * To reset to the global default behavior (as set by
 * SOCK_SetReadOnWriteAPI), call this function with "on_off" == eDefault.
 * Return prior setting.
 */
extern NCBI_XCONNECT_EXPORT ESwitch SOCK_SetReadOnWrite
(SOCK    sock,
 ESwitch on_off
 );



/******************************************************************************
 *  Connectionless (datagram) sockets
 *
 *  How the datagram exchange API works:
 *
 *  Datagram socket is created with special DSOCK_Create[Ex] calls but the
 *  resulting object is a SOCK handle. That is, almost all SOCK routines
 *  may be applied to the handle. There are few exceptions, though.
 *  In datagram sockets I/O differs from how it is done in stream sockets:
 *
 *  SOCK_Write() writes data into an internal message buffer, appending new
 *  data as they come with each SOCK_Write(). When the message is complete,
 *  SOCK_SendMsg() should be called (optionally with additional last,
 *  or the only [if no SOCK_Write() preceded the call] message fragment)
 *  to actually send the message down the wire. If successful, SOCK_SendMsg()
 *  cleans the internal buffer, and the process may repeat. If unsuccessful,
 *  SOCK_SendMsg() can be repeated with restiction that no additional data are
 *  provided in the call. This way, the entire message will be attempted to
 *  be sent again. On the other hand, if after any SOCK_SendMsg() new data
 *  are added [regardless of whether previous data were successfully sent
 *  or not], all previously written [and kept in the internal send buffer]
 *  data get dropped and replaced with the new data.
 *
 *  DSOCK_WaitMsg() can be used to learn whether there is a new message
 *  available for read by DSOCK_RecvMsg() immediately.
 *
 *  SOCK_RecvMsg() receives the message into an internal receive buffer,
 *  and optionally can return the initial datagram fragment via provided
 *  buffer [this initial fragment is then stripped from what remains unread
 *  in the internal buffer]. Optimized version can supply a maximal message
 *  size (if known in advance), or 0 to get a message of any allowed size.
 *  The actual size of the received message can be obtained via a
 *  pointer-type argument 'msgsize'. The message kept in the internal buffer
 *  can be read out in several SOCK_Read() calls, last returning eIO_Closed,
 *  when all data have been taken out. SOCK_Wait() returns eIO_Success while
 *  there are data in the internal message buffer that SOCK_Read() can read.
 *
 *  SOCK_WipeMsg() can be used to clear the internal message buffers in
 *  either eIO_Read or eIO_Write directions, meaning receive and send
 *  buffers correspondingly.
 */


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_Create
(SOCK*           sock                   /* [out] socket created              */
 );


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_CreateEx
(SOCK*           sock,                  /* [out] socket created              */
 ESwitch         log                    /* [in]  whether to log data activity*/
 );


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_Bind
(SOCK            sock,                  /* [in]  SOCK from DSOCK_Create[Ex]()*/
 unsigned short  port                   /* [in]  port to bind to (!=0)       */
 );


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_Connect
(SOCK            sock,                  /* [in]  SOCK from DSOCK_Create[Ex]()*/
 const char*     host,                  /* [in]  peer host                   */
 unsigned short  port                   /* [in]  peer port                   */
 );


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_WaitMsg
(SOCK            sock,                  /* [in]  SOCK from DSOCK_Create[Ex]()*/
 const STimeout* timeout                /* [in]  time to wait for message    */
 );


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_SendMsg
(SOCK            sock,                  /* [in]  SOCK from DSOCK_Create[Ex]()*/
 const char*     host,                  /* [in]  hostname or dotted IP       */
 unsigned short  port,                  /* [in]  port number, host byte order*/
 const void*     data,                  /* [in]  additional data to send     */
 size_t          datalen                /* [in]  size of addtl data (bytes)  */
 );


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_RecvMsg
(SOCK            sock,                  /* [in]  SOCK from DSOCK_Create[Ex]()*/
 void*           buf,                   /* [in]  buf to store msg at,m.b.NULL*/
 size_t          buflen,                /* [in]  buf length provided         */
 size_t          maxmsglen,             /* [in]  maximal expected message len*/
 size_t*         msglen,                /* [out] actual msg size, may be NULL*/
 unsigned int*   sender_addr,           /* [out] net byte order, may be NULL */
 unsigned short* sender_port            /* [out] host byte order, may be NULL*/
);


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_WipeMsg
(SOCK            sock,                  /* [in]  SOCK from DSOCK_Create[Ex]()*/
 EIO_Event       direction              /* [in]  either of eIO_Read|eIO_Write*/
 );


extern NCBI_XCONNECT_EXPORT EIO_Status DSOCK_SetBroadcast
(SOCK            sock,                  /* [in]  SOCK from DSOCK_Create[Ex]()*/
 int/*bool*/     broadcast              /* [in]  set(1)/unset(0) bcast capab.*/
 );



/******************************************************************************
 *  Type information for SOCK sockets
 */


/* Return non-zero value if socket "sock" was created by DSOCK_Create[Ex]().
 * Return zero otherwise.
 */
extern NCBI_XCONNECT_EXPORT int/*bool*/ SOCK_IsDatagram(SOCK sock);


/* Return non-zero value if socket "sock" was created by SOCK_Create[Ex]().
 * Return zero otherwise.
 */
extern NCBI_XCONNECT_EXPORT int/*bool*/ SOCK_IsClientSide(SOCK sock);


/* Return non-zero value if socket "sock" was created by LSOCK_Accept().
 * Return zero otherwise.
 */
extern NCBI_XCONNECT_EXPORT int/*bool*/ SOCK_IsServerSide(SOCK sock);



/******************************************************************************
 *  AUXILIARY network-specific functions (added for the portability reasons)
 */


/* Return zero on success, non-zero on error.  See BSD gethostname().
 * On error "name" returned emptied (name[0] == '\0').
 */
extern NCBI_XCONNECT_EXPORT int SOCK_gethostname
(char*  name,          /* [out] (guaranteed to be '\0'-terminated)           */
 size_t namelen        /* [in]  max # of bytes allowed to put to "name"      */
 );


/* Return zero on success, non-zero on error.  Vaguely related to BSD's
 * inet_ntoa(). On error "buf" returned emptied (buf[0] == '\0').
 */
extern NCBI_XCONNECT_EXPORT int SOCK_ntoa
(unsigned int addr,      /* [in]  must be in the network byte-order          */
 char*        buf,       /* [out] to be filled by smth. like "123.45.67.89\0"*/
 size_t       buflen     /* [in]  max # of bytes to put to "buf"             */
 );


/* See man for the BSDisms, htonl() and htons().
 */
extern NCBI_XCONNECT_EXPORT unsigned int SOCK_HostToNetLong
(unsigned int value
 );

#define SOCK_NetToHostLong SOCK_HostToNetLong

extern NCBI_XCONNECT_EXPORT unsigned short SOCK_HostToNetShort
(unsigned short value
 );

#define SOCK_NetToHostShort SOCK_HostToNetShort

/* Deprecated */
#define SOCK_htonl SOCK_HostToNetLong
#define SOCK_ntohl SOCK_NetToHostLong
#define SOCK_htons SOCK_HostToNetShort
#define SOCK_ntohs SOCK_NetToHostShort


/* Return INET host address (in network byte order) of the
 * specified host (or local host, if hostname is passed as NULL),
 * which can be either domain name or an IP address in
 * dotted notation (e.g. "123.45.67.89\0"). Return 0 on error.
 * NOTE: "0.0.0.0" and "255.255.255.255" are considered invalid.
 */
extern NCBI_XCONNECT_EXPORT unsigned int SOCK_gethostbyname
(const char* hostname  /* [in]  return current host address if hostname is 0 */
 );


/* Take INET host address (in network byte order) and fill out the
 * the provided buffer with the name, which the address corresponds to
 * (in case of multiple names the primary name is used). Return value 0
 * means error, while success is denoted by the 'name' argument returned.
 * Note that on error the name returned emptied (name[0] == '\0').
 */
extern NCBI_XCONNECT_EXPORT char* SOCK_gethostbyaddr
(unsigned int addr,    /* [in]  host address in network byte order           */
 char*        name,    /* [out] buffer to put the name to                    */
 size_t       namelen  /* [in]  size (bytes) of the buffer above             */
 );


#ifdef __cplusplus
} /* extern "C" */
#endif


/* @} */


/*
 * ---------------------------------------------------------------------------
 * $Log: ncbi_socket.h,v $
 * Revision 6.50  2004/07/23 19:04:38  lavr
 * LSOCK_CreateEx(): last parameter to become flags (bitmask)
 *
 * Revision 6.49  2004/03/23 02:26:55  lavr
 * Typo fix
 *
 * Revision 6.48  2003/11/25 15:07:12  lavr
 * SOCK_Status() to accept eIO_Open
 *
 * Revision 6.47  2003/11/24 19:22:24  lavr
 * SetSelectInternalRestartTimeout() to accept ptr to STimeout
 *
 * Revision 6.46  2003/11/18 20:18:49  lavr
 * +SetSelectInternalRestartTimeout()
 *
 * Revision 6.45  2003/11/12 17:43:08  lavr
 * +SOCK_CloseEx()
 *
 * Revision 6.44  2003/10/24 16:51:11  lavr
 * GetTimeout(eIO_ReadWrite): return the lesser of eIO_Read and eIO_Write
 *
 * Revision 6.43  2003/10/23 12:14:33  lavr
 * Socket feature setters made returning old feature values
 *
 * Revision 6.42  2003/09/23 21:04:43  lavr
 * SOCK_Abort():  argument comment removed as irrelevant (cut&paste mishap)
 *
 * Revision 6.41  2003/08/25 14:38:00  lavr
 * Introduce POLLABLE_Poll() and [L]SOCK<->POLLABLE conversion routines
 *
 * Revision 6.40  2003/07/15 16:42:09  lavr
 * +SOCK_GetPeerAddressString()
 *
 * Revision 6.39  2003/06/12 13:21:21  lavr
 * Added eIO_Timeout as a return code for SOCK_Status()
 *
 * Revision 6.38  2003/05/20 21:24:32  lavr
 * SOCK_Write(): note added on writing 0 bytes to a socket
 *
 * Revision 6.37  2003/05/19 16:42:07  lavr
 * +SOCK_SetReuseAddress[API]() - both EXPERIMENTAL!
 *
 * Revision 6.36  2003/05/14 03:46:15  lavr
 * Revised API to include {0,0} connect timeouts, initial data block
 * Revised datagram socket API
 *
 * Revision 6.35  2003/04/30 16:59:05  lavr
 * Added notice about how datagram API is supposed to work
 *
 * Revision 6.34  2003/04/11 20:57:43  lavr
 * DSOCK_Connect() documented
 *
 * Revision 6.33  2003/04/09 19:05:54  siyan
 * Added doxygen support
 *
 * Revision 6.32  2003/04/04 21:00:09  lavr
 * +SOCK_CreateOnTop()
 *
 * Revision 6.31  2003/01/17 01:32:30  lavr
 * +LSOCK_CreateEx()
 *
 * Revision 6.30  2003/01/16 16:30:57  lavr
 * Add prototype for DSOCK_WipeMsg()
 *
 * Revision 6.29  2003/01/15 19:50:45  lavr
 * Datagram socket interface revised
 *
 * Revision 6.28  2003/01/08 01:59:33  lavr
 * DLL-ize CONNECT library for MSVC (add NCBI_XCONNECT_EXPORT)
 *
 * Revision 6.27  2003/01/07 22:01:43  lavr
 * ChangeLog message corrected
 *
 * Revision 6.26  2003/01/07 21:58:24  lavr
 * Draft DSOCK interface added
 *
 * Revision 6.25  2002/12/05 21:44:50  lavr
 * Retire SOCK_Create() as a macro; reinstate as a regular call
 *
 * Revision 6.24  2002/12/04 16:53:12  lavr
 * Introduce SOCK_CreateEx()
 *
 * Revision 6.23  2002/11/01 20:12:06  lavr
 * Specifically state which IP/name manip. routines do emtpy output buffer
 *
 * Revision 6.22  2002/09/19 18:07:06  lavr
 * Consistency check moved up to be the first thing
 *
 * Revision 6.21  2002/08/27 03:15:01  lavr
 * Deprecate SOCK_{nh}to{hn}{ls}, define more elaborate call names
 * SOCK_{Net|Host}To{Host|Net}{Long|Short} instead
 *
 * Revision 6.20  2002/08/15 18:44:18  lavr
 * SOCK_Poll() documented in more details
 *
 * Revision 6.19  2002/08/12 14:59:12  lavr
 * Additional (last) argument for SOCK_Write: write_mode
 *
 * Revision 6.18  2002/08/07 16:31:00  lavr
 * Added enum ENH_ByteOrder; renamed SOCK_GetAddress() ->
 * SOCK_GetPeerAddress() and now accepts ENH_ByteOrder as last arg;
 * added SOCK_SetInterruptOnSignal[API]; write-status (w_status) made current;
 * log moved to end
 *
 * Revision 6.17  2002/04/26 16:40:43  lavr
 * New method: SOCK_Poll()
 *
 * Revision 6.16  2002/04/22 20:52:34  lavr
 * +SOCK_htons(), macros SOCK_ntohl() and SOCK_ntohs()
 *
 * Revision 6.15  2001/12/03 21:33:48  vakatov
 * + SOCK_IsServerSide()
 *
 * Revision 6.14  2001/09/10 16:10:41  vakatov
 * SOCK_gethostbyname() -- special cases "0.0.0.0" and "255.255.255.255"
 *
 * Revision 6.13  2001/05/21 15:11:46  ivanov
 * Added (with Denis Vakatov) automatic read on write data from the socket
 * (stall protection).
 * Added functions SOCK_SetReadOnWriteAPI(), SOCK_SetReadOnWrite()
 * and internal function s_SelectStallsafe().
 *
 * Revision 6.12  2001/04/23 22:22:06  vakatov
 * SOCK_Read() -- special treatment for "buf" == NULL
 *
 * Revision 6.11  2001/03/22 17:44:14  vakatov
 * + SOCK_AllowSigPipeAPI()
 *
 * Revision 6.10  2001/03/06 23:54:10  lavr
 * Renamed: SOCK_gethostaddr -> SOCK_gethostbyname
 * Added:   SOCK_gethostbyaddr
 *
 * Revision 6.9  2001/03/02 20:05:15  lavr
 * Typos fixed
 *
 * Revision 6.8  2000/12/26 21:40:01  lavr
 * SOCK_Read modified to handle properly the case of 0 byte reading
 *
 * Revision 6.7  2000/12/05 23:27:44  lavr
 * Added SOCK_gethostaddr
 *
 * Revision 6.6  2000/11/15 18:51:05  vakatov
 * Add SOCK_Shutdown() and SOCK_Status().  Remove SOCK_Eof().
 *
 * Revision 6.5  2000/06/23 19:34:41  vakatov
 * Added means to log binary data
 *
 * Revision 6.4  2000/05/30 23:31:37  vakatov
 * SOCK_host2inaddr() renamed to SOCK_ntoa(), the home-made out-of-scratch
 * implementation to work properly with GCC on IRIX64 platforms
 *
 * Revision 6.3  2000/03/24 23:12:04  vakatov
 * Starting the development quasi-branch to implement CONN API.
 * All development is performed in the NCBI C++ tree only, while
 * the NCBI C tree still contains "frozen" (see the last revision) code.
 *
 * Revision 6.2  2000/02/23 22:33:38  vakatov
 * Can work both "standalone" and as a part of NCBI C++ or C toolkits
 *
 * Revision 6.1  1999/10/18 15:36:39  vakatov
 * Initial revision (derived from the former "ncbisock.[ch]")
 *
 * ===========================================================================
 */

#endif /* CONNECT___NCBI_SOCKET__H */
