forked from johnjohnsp1/capsule8
/
chargen.go
99 lines (85 loc) · 2.31 KB
/
chargen.go
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// Copyright 2017 Capsule8, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package sensor
import (
api "github.com/capsule8/capsule8/api/v0"
"github.com/capsule8/capsule8/pkg/stream"
)
type chargen struct {
ctrl chan interface{}
data chan interface{}
sensor *Sensor
filter *api.ChargenEventFilter
chargen *stream.Stream
index uint64
length uint64
payload []byte
}
func (c *chargen) newChargenEvent(index uint64, characters string) *api.Event {
e := c.sensor.NewEvent()
e.Event = &api.Event_Chargen{
Chargen: &api.ChargenEvent{
Index: index,
Characters: characters,
},
}
return e
}
func (c *chargen) emitNextEvent(e interface{}) {
i := c.index % uint64(c.length)
str := e.(string)
c.payload[i] = str[0]
c.index++
if (c.index % uint64(c.length)) == 0 {
c.data <- c.newChargenEvent(c.index, string(c.payload))
}
}
func newChargenSource(sensor *Sensor, filter *api.ChargenEventFilter) (*stream.Stream, error) {
// Each call to New creates a new session with the Sensor. It is the
// Sensor's responsibility to handle all of its sessions in the most
// high-performance way possible. For example, a Sensor may install
// kernel probes for the union of all sessions, but then demux the
// results through individual goroutines forwarding events over
// their own channels.
c := &chargen{
ctrl: make(chan interface{}),
data: make(chan interface{}),
sensor: sensor,
filter: filter,
chargen: stream.Chargen(),
index: 0,
length: filter.Length,
payload: make([]byte, filter.Length),
}
go func() {
for {
select {
case _, ok := <-c.ctrl:
if !ok {
close(c.data)
return
}
case e, ok := <-c.chargen.Data:
if !ok {
return
}
c.emitNextEvent(e)
}
}
}()
return &stream.Stream{
Ctrl: c.ctrl,
Data: c.data,
}, nil
}