forked from openkylin/libssh2
77 lines
3.1 KiB
Groff
77 lines
3.1 KiB
Groff
.TH libssh2_session_callback_set 3 "1 Jun 2007" "libssh2 0.15" "libssh2 manual"
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.SH NAME
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libssh2_session_callback_set - set a callback function
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.SH SYNOPSIS
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.nf
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#include <libssh2.h>
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void *libssh2_session_callback_set(LIBSSH2_SESSION *session,
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int cbtype, void *callback);
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.SH DESCRIPTION
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Sets a custom callback handler for a previously initialized session
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object. Callbacks are triggered by the receipt of special packets at the
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Transport layer. To disable a callback, set it to NULL.
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\fIsession\fP - Session instance as returned by
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.BR libssh2_session_init_ex(3)
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\fIcbtype\fP - Callback type. One of the types listed in Callback Types.
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\fIcallback\fP - Pointer to custom callback function. The prototype for
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this function must match the associated callback declaration macro.
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.SH CALLBACK TYPES
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.IP LIBSSH2_CALLBACK_IGNORE
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Called when a SSH_MSG_IGNORE message is received
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.IP LIBSSH2_CALLBACK_DEBUG
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Called when a SSH_MSG_DEBUG message is received
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.IP LIBSSH2_CALLBACK_DISCONNECT
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Called when a SSH_MSG_DISCONNECT message is received
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.IP LIBSSH2_CALLBACK_MACERROR
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Called when a mismatched MAC has been detected in the transport layer. If the
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function returns 0, the packet will be accepted nonetheless.
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.IP LIBSSH2_CALLBACK_X11
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Called when an X11 connection has been accepted
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.IP LIBSSH2_CALLBACK_SEND
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Called when libssh2 wants to send data on the connection. Can be set to a
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custom function to handle I/O your own way.
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The prototype of the callback:
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.nf
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ssize_t sendcb(libssh2_socket_t sockfd, const void *buffer,
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size_t length, int flags, void **abstract);
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.fi
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\fBsockfd\fP is the socket to write to, \fBbuffer\fP points to the data to
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send, \fBlength\fP is the size of the data, \fBflags\fP is the flags that
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would've been used to a \fIsend()\fP call and \fBabstract\fP is a pointer to
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the abstract pointer set in the \fIlibssh2_session_init_ex(3)\fP call.
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The callback returns the number of bytes sent, or -1 for error. The special
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return code \fB-EAGAIN\fP can be returned to signal that the send was aborted
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to prevent getting blocked and it needs to be called again.
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.IP LIBSSH2_CALLBACK_RECV
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Called when libssh2 wants to read data from the connection. Can be set to a
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custom function to handle I/O your own way.
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The prototype of the callback:
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.nf
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ssize_t recvcb(libssh2_socket_t sockfd, void *buffer,
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size_t length, int flags, void **abstract);
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.fi
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\fBsockfd\fP is the socket to read from, \fBbuffer\fP where to store received
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data into, \fBlength\fP is the size of the buffer, \fBflags\fP is the flags
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that would've been used to a \fIrecv()\fP call and \fBabstract\fP is a pointer
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to the abstract pointer set in the \fIlibssh2_session_init_ex(3)\fP call.
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The callback returns the number of bytes read, or -1 for error. The special
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return code \fB-EAGAIN\fP can be returned to signal that the read was aborted
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to prevent getting blocked and it needs to be called again.
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.SH RETURN VALUE
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Pointer to previous callback handler. Returns NULL if no prior callback
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handler was set or the callback type was unknown.
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.SH SEE ALSO
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.BR libssh2_session_init_ex(3)
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