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/*
* Copyright (c) 2019 by Farsight Security, 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 dnstap
import (
framestream "github.com/farsightsec/golang-framestream"
"google.golang.org/protobuf/proto"
)
// A Decoder reads and parses Dnstap messages from an io.Reader
type Decoder struct {
buf []byte
r Reader
}
// NewDecoder creates a Decoder using the given dnstap Reader, accepting
// dnstap data frames up to maxSize in size.
func NewDecoder(r Reader, maxSize int) *Decoder {
return &Decoder{
buf: make([]byte, maxSize),
r: r,
}
}
// Decode reads and parses a Dnstap message from the Decoder's Reader.
// Decode silently discards data frames larger than the Decoder's configured
// maxSize.
func (d *Decoder) Decode(m *Dnstap) error {
for {
n, err := d.r.ReadFrame(d.buf)
switch err {
case framestream.ErrDataFrameTooLarge:
continue
case nil:
break
default:
return err
}
return proto.Unmarshal(d.buf[:n], m)
}
}
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