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soclose (9)
  • >> soclose (9) ( FreeBSD man: Ядро )

  • BSD mandoc
     

    NAME

    
    
    socket
    
     - kernel socket interface
    
     
    

    SYNOPSIS

       #include <sys/socket.h>
       #include <sys/socketvar.h>
    int sobind (struct socket *so struct sockaddr *nam struct thread *td);
    void soclose (struct socket *so);
    int soconnect (struct socket *so struct sockaddr *nam struct thread *td);
    int Fo socreate Fa int dom struct socket **aso int type int proto Fa struct ucred *cred struct thread *td Fc Ft int sogetopt (struct socket *so struct sockopt *sopt);
    int Fo soreceive Fa struct socket *so struct sockaddr **psa struct uio *uio Fa struct mbuf **mp0 struct mbuf **controlp int *flagsp Fc Ft int sosetopt (struct socket *so struct sockopt *sopt);
    int Fo sosend Fa struct socket *so struct sockaddr *addr struct uio *uio Fa struct mbuf *top struct mbuf *control int flags struct thread *td Fc Ft int soshutdown (struct socket *so int how);
     

    DESCRIPTION

    The kernel programming interface permits in-kernel consumers to interact with local and network socket objects in a manner similar to that permitted using the socket(2) user API. These interfaces are appropriate for use by distributed file systems and other network-aware kernel services. While the user API operates on file descriptors, the kernel interfaces operate directly on Vt struct socket pointers.

    Except where otherwise indicated, functions may sleep, and are not appropriate for use in an ithread(9) context or while holding non-sleepable kernel locks.  

    Creating and Destroying Sockets

    A new socket may be created using socreate (.);
    As with socket(2), arguments specify the requested domain, type, and protocol via Fa dom , type , and Fa proto . The socket is returned via Fa aso on success. In addition, the credential used to authorize operations associated with the socket will be passed via Fa cred (and will be cached for the lifetime of the socket), and the thread performing the operation via Fa td . Warning authorization of the socket creation operation will be performed using the thread credential for some protocols (such as raw sockets).

    Sockets may be closed and freed using soclose (,);
    which has similar semantics to close(2).  

    Connections and Addresses

    The sobind ();
    function is equivalent to the bind(2) system call, and binds the socket Fa so to the address Fa nam . The operation would be authorized using the credential on thread Fa td .

    The soconnect ();
    function is equivalent to the connect(2) system call, and initiates a connection on the socket Fa so to the address Fa nam . The operation will be authorized using the credential on thread Fa td . Unlike the user system call, soconnect ();
    returns immediately; the caller may msleep(9) on Fa so->so_timeo while holding the socket mutex and waiting for the SS_ISCONNECTING flag to clear or Fa so->so_error to become non-zero. If soconnect ();
    fails, the caller must manually clear the SS_ISCONNECTING flag.

    The soshutdown ();
    function is equivalent to the shutdown(2) system call, and causes part or all of a connection on a socket to be closed down.  

    Socket Options

    The sogetopt ();
    function is equivalent to the getsockopt(2) system call, and retrieves a socket option on socket Fa so . The sosetopt ();
    function is equivalent to the setsockopt(2) system call, and sets a socket option on socket Fa so .

    The second argument in both sogetopt ();
    and sosetopt ();
    is the Fa sopt pointer to a Vt struct sopt describing the socket option operation. The caller-allocated structure must be zeroed, and then have its fields initialized to specify socket option operation arguments:

    sopt_dir
    Set to SOPT_SET or SOPT_GET depending on whether this is a get or set operation.
    sopt_level
    Specify the level in the network stack the operation is targeted at; for example, SOL_SOCKET
    sopt_name
    Specify the name of the socket option to set.
    sopt_val
    Kernel space pointer to the argument value for the socket option.
    sopt_valsize
    Size of the argument value in bytes.

     

    Socket I/O

    The soreceive ();
    function is equivalent to the recvmsg(2) system call, and attempts to receive bytes of data from the socket Fa so , optionally blocking awaiting for data if none is ready to read. Data may be retrieved directly to kernel or user memory via the Fa uio argument, or as an mbuf chain returned to the caller via Fa mp0 , avoiding a data copy. Only one of the Fa uio or Fa mp0 pointers may be non- NULL The caller may optionally retrieve a socket address on a protocol with the PR_ADDR capability by providing storage via non- NULL Fa psa argument. The caller may optionally retrieve control data mbufs via a non- NULL Fa controlp argument. Optional flags may be passed to soreceive ();
    via a non- NULL Fa flagsp argument, and use the same flag name space as the recvmsg(2) system call.

    The sosend ();
    function is equivalent to the sendmsg(2) system call, and attempts to send bytes of data via the socket Fa so , optionally blocking if data cannot be immediately sent. Data may be sent directly from kernel or user memory via the Fa uio argument, or as an mbuf chain via Fa top , avoiding a data copy. Only one of the Fa uio or Fa top pointers may be non- NULL An optional destination address may be specified via a non- NULL Fa addr argument, which may result in an implicit connect if supported by the protocol. The caller may optionally send control data mbufs via a non- NULL Fa control argument. Flags may be passed to sosend ();
    using the Fa flags argument, and use the same flag name space as the sendmsg(2) system call.

    Kernel callers running in ithread(9) context, or with a mutex held, will wish to use non-blocking sockets and pass the MSG_DONTWAIT flag in order to prevent these functions from sleeping.  

    SEE ALSO

    bind(2), close(2), connect(2), getsockopt(2), recv(2), send(2), setsockopt(2), shutdown(2), socket(2), ng_ksocket4, ithread(9), msleep(9), ucred(9)  

    HISTORY

    The socket(2) system call appeared in BSD 4.2 This manual page was introduced in Fx 7.0 .  

    AUTHORS

    This manual page was written by An Robert Watson .  

    BUGS

    The use of explicitly passed credentials, credentials hung from explicitly passed threads, the credential on curthread and the cached credential from socket creation time is inconsistent, and may lead to unexpected behaviour. It is possible that several of the Fa td arguments should be Fa cred arguments, or simply not be present at all.

    The caller may need to manually clear SS_ISCONNECTING if soconnect ();
    returns an error.

    The MSG_DONTWAIT flag is not implemented for sosend (,);
    and may not always work with soreceive ();
    when zero copy sockets are enabled.

    This manual page does not describe how to register socket upcalls or monitor a socket for readability/writability without using blocking I/O.

    The soref ();
    and sorele ();
    functions are not described, and in most cases should not be used, due to confusing and potentially incorrect interactions when sorele ();
    is last called after soclose (.);


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    Creating and Destroying Sockets
    Connections and Addresses
    Socket Options
    Socket I/O
    SEE ALSO
    HISTORY
    AUTHORS
    BUGS


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