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NgRecvAsciiMsg ()
  • >> NgRecvAsciiMsg (3) ( FreeBSD man: Библиотечные вызовы )

  • BSD mandoc
     

    NAME

    
    
    NgMkSockNode
    
     
    NgNameNode
    
     
    NgSendMsg
    
     
    NgSendAsciiMsg
    
     
    NgSendMsgReply
    
     
    NgRecvMsg
    
     
    NgAllocRecvMsg
    
     
    NgRecvAsciiMsg
    
     
    NgAllocRecvAsciiMsg
    
     
    NgSendData
    
     
    NgRecvData
    
     
    NgAllocRecvData
    
     
    NgSetDebug
    
     
    NgSetErrLog
    
     - netgraph user library
    
     
    

    LIBRARY

    Lb libnetgraph
    
     
    

    SYNOPSIS

       #include <netgraph.h>
    int NgMkSockNode (const char *name int *csp int *dsp);
    int NgNameNode (int cs const char *path const char *fmt ...);
    int Fo NgSendMsg Fa int cs const char *path int cookie int cmd const void *arg Fa size_t arglen Fc Ft int NgSendAsciiMsg (int cs const char *path const char *fmt ...);
    int Fo NgSendMsgReply Fa int cs const char *path struct ng_mesg *msg const void *arg Fa size_t arglen Fc Ft int NgRecvMsg (int cs struct ng_mesg *rep size_t replen char *path);
    int NgAllocRecvMsg (int cs struct ng_mesg **rep char *path);
    int NgRecvAsciiMsg (int cs struct ng_mesg *rep size_t replen char *path);
    int NgAllocRecvAsciiMsg (int cs struct ng_mesg **rep char *path);
    int NgSendData (int ds const char *hook const u_char *buf size_t len);
    int NgRecvData (int ds u_char *buf size_t len char *hook);
    int NgAllocRecvData (int ds u_char **buf char *hook);
    int NgSetDebug (int level);
    void Fo NgSetErrLog Fa void lp]*logrp]lp]const char *fmt, ...rp] Fa void lp]*logxrp]lp]const char *fmt, ...rp] Fc  

    DESCRIPTION

    These functions facilitate user-mode program participation in the kernel netgraph(4) graph-based networking system, by utilizing the netgraph Vt socket node type (see ng_socket4).

    The NgMkSockNode ();
    function should be called first, to create a new Vt socket type netgraph node with associated control and data sockets. If Fa name is non- NULL the node will have that global name assigned to it. The Fa csp and Fa dsp arguments will be set to the newly opened control and data sockets associated with the node; either Fa csp or Fa dsp may be NULL if only one socket is desired. The NgMkSockNode ();
    function loads the Vt socket node type KLD if it is not already loaded.

    The NgNameNode ();
    function assigns a global name to the node addressed by Fa path .

    The NgSendMsg ();
    function sends a binary control message from the Vt socket node associated with control socket Fa cs to the node addressed by Fa path . The Fa cookie indicates how to interpret Fa cmd , which indicates a specific command. Extra argument data (if any) is specified by Fa arg and Fa arglen . The Fa cookie , cmd , and argument data are defined by the header file corresponding to the type of the node being addressed. The unique, non-negative token value chosen for use in the message header is returned. This value is typically used to associate replies.

    Use NgSendMsgReply ();
    to send reply to a previously received control message. The original message header should be pointed to by Fa msg .

    The NgSendAsciiMsg ();
    function performs the same function as NgSendMsg (,);
    but adds support for ASCII encoding of control messages. The NgSendAsciiMsg ();
    function formats its input a la printf(3) and then sends the resulting ASCII string to the node in a NGM_ASCII2BINARY control message. The node returns a binary version of the message, which is then sent back to the node just as with NgSendMsg (.);
    As with NgSendMsg (,);
    the message token value is returned. Note that ASCII conversion may not be supported by all node types.

    The NgRecvMsg ();
    function reads the next control message received by the node associated with control socket Fa cs . The message and any extra argument data must fit in Fa replen bytes. If Fa path is non- NULL it must point to a buffer of at least NG_PATHSIZ bytes, which will be filled in (and NUL terminated) with the path to the node from which the message was received.

    The length of the control message is returned. A return value of zero indicates that the socket was closed.

    The NgAllocRecvMsg ();
    function works exactly like NgRecvMsg (,);
    except that the buffer for a message is dynamically allocated to guarantee that a message is not truncated. The size of the buffer is equal to the socket's receive buffer size. The caller is responsible for freeing the buffer when it is no longer required.

    The NgRecvAsciiMsg ();
    function works exactly like NgRecvMsg (,);
    except that after the message is received, any binary arguments are converted to ASCII by sending a NGM_BINARY2ASCII request back to the originating node. The result is the same as NgRecvMsg (,);
    with the exception that the reply arguments field will contain a NUL -terminated ASCII version of the arguments (and the reply header argument length field will be adjusted).

    The NgAllocRecvAsciiMsg ();
    function works exactly like NgRecvAsciiMsg (,);
    except that the buffer for a message is dynamically allocated to guarantee that a message is not truncated. The size of the buffer is equal to the socket's receive buffer size. The caller is responsible for freeing the buffer when it is no longer required.

    The NgSendData ();
    function writes a data packet out on the specified hook of the node corresponding to data socket Fa ds . The node must already be connected to some other node via that hook.

    The NgRecvData ();
    function reads the next data packet (of up to Fa len bytes) received by the node corresponding to data socket Fa ds and stores it in Fa buf , which must be large enough to hold the entire packet. If Fa hook is non- NULL it must point to a buffer of at least NG_HOOKSIZ bytes, which will be filled in (and NUL terminated) with the name of the hook on which the data was received.

    The length of the packet is returned. A return value of zero indicates that the socket was closed.

    The NgAllocRecvData ();
    function works exactly like NgRecvData (,);
    except that the buffer for a data packet is dynamically allocated to guarantee that a data packet is not truncated. The size of the buffer is equal to the socket's receive buffer size. The caller is responsible for freeing the buffer when it is no longer required.

    The NgSetDebug ();
    and NgSetErrLog ();
    functions are used for debugging. The NgSetDebug ();
    function sets the debug level (if non-negative), and returns the old setting. Higher debug levels result in more verbosity. The default is zero. All debug and error messages are logged via the functions specified in the most recent call to NgSetErrLog (.);
    The default logging functions are vwarn(3) and vwarnx(3).

    At debug level 3, the library attempts to display control message arguments in ASCII format; however, this results in additional messages being sent which may interfere with debugging. At even higher levels, even these additional messages will be displayed, etc.

    Note that select(2) can be used on the data and the control sockets to detect the presence of incoming data and control messages, respectively. Data and control packets are always written and read atomically, i.e., in one whole piece.

    User mode programs must be linked with the -l netgraph flag to link in this library.  

    INITIALIZATION

    To enable netgraph in your kernel, either your kernel must be compiled with options NETGRAPH in the kernel configuration file, or else the netgraph(4) and ng_socket4 KLD modules must have been loaded via kldload(8).  

    RETURN VALUES

    The NgSetDebug ();
    function returns the previous debug setting.

    The NgSetErrLog ();
    function has no return value.

    All other functions return -1 if there was an error and set errno accordingly.

    A return value of zero from NgRecvMsg ();
    or NgRecvData ();
    indicates that the netgraph socket has been closed.

    For NgSendAsciiMsg ();
    and NgRecvAsciiMsg (,);
    the following additional errors are possible:

    Bq Er ENOSYS
    The node type does not know how to encode or decode the control message.
    Bq Er ERANGE
    The encoded or decoded arguments were too long for the supplied buffer.
    Bq Er ENOENT
    An unknown structure field was seen in an ASCII control message.
    Bq Er EALREADY
    The same structure field was specified twice in an ASCII control message.
    Bq Er EINVAL
    ASCII control message parse error or illegal value.
    Bq Er E2BIG
    ASCII control message array or fixed width string buffer overflow.

     

    SEE ALSO

    select(2), socket(2), warnx(3), kld(4), netgraph(4), ng_socket4  

    HISTORY

    The netgraph system was designed and first implemented at Whistle Communications, Inc. in a version of Fx 2.2 customized for the Whistle InterJet.  

    AUTHORS

    An Archie Cobbs Aq archie@FreeBSD.org


     

    Index

    NAME
    LIBRARY
    SYNOPSIS
    DESCRIPTION
    INITIALIZATION
    RETURN VALUES
    SEE ALSO
    HISTORY
    AUTHORS


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