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/*
* Copyright (c) 2017 by Farsight Security, Inc.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
package nmsg
/*
#cgo pkg-config: libnmsg
#cgo LDFLAGS: -lnmsg
#include <stdlib.h>
#include <nmsg.h>
extern nmsg_res inputCallback(nmsg_message_t *msg, void *user);
nmsg_res input_callback(nmsg_message_t *msg, void *user) {
return inputCallback(msg, user);
}
*/
import "C"
import (
"io"
"net"
"os"
"unsafe"
)
// An Input is a source of NMSG payloads (Messages).
type Input interface {
// Read returns a Message or nil, and an error if any.
Read() (*Message, error)
// SetFilterMsgtype instructs the input to discard all Messages
// not of the given vendor id and msgtype, specified by number.
SetFilterMsgtype(vendor, msgtype uint32)
// SetFilterMsgtypeByname instructs the input to discard all Messages
// not of the given vendor id and msgtype, specified by name.
SetFilterMsgtypeByname(vendor, msgtype string)
// SetFilterSource instructs the input to discard all Messages not
// from the supplied source.
SetFilterSource(source uint32)
// SetFilterOperator instructs the input to discard all Messages not
// from the supplied operator.
SetFilterOperator(operator uint32)
// SetFilterGroup instructs the input to discard all Messages not
// in the supplied group.
SetFilterGroup(group uint32)
}
// NmsgInput is an Input managed by libnmsg. It satisfies
// the Input interface, and has
type nmsgInput struct {
file *os.File
input C.nmsg_input_t
}
func (i *nmsgInput) Read() (*Message, error) {
var msg C.nmsg_message_t
res := C.nmsg_input_read(i.input, &msg)
if res == C.nmsg_res_success {
return messageFromC(msg), nil
}
return nil, nmsgError(res)
}
func (i *nmsgInput) SetFilterMsgtype(vid, msgtype uint32) {
C.nmsg_input_set_filter_msgtype(i.input, C.uint(vid), C.uint(msgtype))
}
func (i *nmsgInput) SetFilterMsgtypeByname(vendor, msgtype string) {
cname := C.CString(vendor)
ctype := C.CString(msgtype)
C.nmsg_input_set_filter_msgtype_byname(i.input, cname, ctype)
C.free(unsafe.Pointer(cname))
C.free(unsafe.Pointer(ctype))
}
func (i *nmsgInput) SetFilterSource(source uint32) {
C.nmsg_input_set_filter_source(i.input, C.uint(source))
}
func (i *nmsgInput) SetFilterOperator(operator uint32) {
C.nmsg_input_set_filter_operator(i.input, C.uint(operator))
}
func (i *nmsgInput) SetFilterGroup(group uint32) {
C.nmsg_input_set_filter_group(i.input, C.uint(group))
}
// NewInput creates a new Input from an io.Reader.
// Currently, the reader must be a *net.UDPConn or a *os.File
func NewInput(r io.Reader) Input {
switch r := r.(type) {
case *net.UDPConn:
f, err := r.File()
if err != nil {
return nil
}
return &nmsgInput{f, C.nmsg_input_open_sock(C.int(f.Fd()))}
case *os.File:
return &nmsgInput{r, C.nmsg_input_open_file(C.int(r.Fd()))}
default:
return nil
// return &containerReader{Reader: r}
}
}
// NewCallbackInput creates an NmsgInput which calls the supplied InputFunc.
func NewCallbackInput(i InputFunc) Input {
return &nmsgInput{
file: nil,
input: C.nmsg_input_open_callback(C.nmsg_cb_message_read(C.input_callback), registerInput(i)),
}
}
// An InputFunc is a function with the same signature as Input.Read(), usable
// directly as an Input.
//
// When used directly as an Input, only the Read() method is implemented. All
// others are no-ops. If the functionality of the other methods is desired,
// the InputFunc can be passed to NewCallbackInput.
type InputFunc func() (*Message, error)
// Read calls the underlying function to return the next message.
func (i InputFunc) Read() (*Message, error) { return i() }
// SetFilterMsgtype satisfies the Input interface with a no-op
func (i InputFunc) SetFilterMsgtype(vendor, msgtype uint32) {}
// SetFilterMsgtypeByname satisfies the Input interface with a no-op
func (i InputFunc) SetFilterMsgtypeByname(vendor, msgtype string) {}
// SetFilterSource satisfies the Input interface with a no-op
func (i InputFunc) SetFilterSource(source uint32) {}
// SetFilterOperator satisfies the Input interface with a no-op
func (i InputFunc) SetFilterOperator(operator uint32) {}
// SetFilterGroup satisfies the Input interface with a no-op
func (i InputFunc) SetFilterGroup(group uint32) {}
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