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base64decode.go
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base64decode.go
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// Copyright 2015 trivago GmbH
//
// 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 format
import (
"encoding/base64"
"fmt"
"github.com/trivago/gollum/core"
"github.com/trivago/gollum/core/log"
"github.com/trivago/gollum/shared"
)
// Base64Decode is a formatter that decodes a base64 message.
// If a message is not or only partly base64 encoded an error will be logged
// and the decoded part is returned. RFC 4648 is expected.
// Configuration example
//
// - "<producer|stream>":
// Formatter: "format.Base64Decode"
// Dictionary: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01234567890+/"
//
// Dictionary defines the 64-character base64 lookup dictionary to use. When
// left empty a dictionary as defined by RFC4648 is used. This is the default.
type Base64Decode struct {
dictionary *base64.Encoding
}
func init() {
shared.RuntimeType.Register(Base64Decode{})
}
// Configure initializes this formatter with values from a plugin config.
func (format *Base64Decode) Configure(conf core.PluginConfig) error {
dict := conf.GetString("Dictionary", "")
if dict == "" {
format.dictionary = base64.StdEncoding
} else {
if len(dict) != 64 {
return fmt.Errorf("Base64 dictionary must contain 64 characters.")
}
format.dictionary = base64.NewEncoding(dict)
}
return nil
}
// Format returns the original message payload
func (format *Base64Decode) Format(msg core.Message) ([]byte, core.MessageStreamID) {
decoded := make([]byte, format.dictionary.DecodedLen(len(msg.Data)))
size, err := format.dictionary.Decode(decoded, msg.Data)
if err != nil {
Log.Error.Print("Base64Decode: ", err)
}
return decoded[:size], msg.StreamID
}