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base64decode.go
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base64decode.go
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// Copyright 2015-2017 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"
"github.com/trivago/gollum/core"
)
// Base64Decode formatter plugin
//
// Base64Decode is a formatter that decodes base64 encoded messages.
// 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.
//
// Parameters
//
// - Base64Dictionary: This value defines the 64-character base64 lookup
// dictionary to use. When left empty, a dictionary as defined by RFC4648 is used.
// By default this parameter is set to "".
//
// Examples
//
// This example expects base64 strings from the console and decodes them before
// transmitting the message payload.
//
// exampleConsumer:
// Type: consumer.Console
// Streams: "*"
// Modulators:
// - format.Base64Decode
//
//
type Base64Decode struct {
core.SimpleFormatter `gollumdoc:"embed_type"`
dictionary *base64.Encoding
}
func init() {
core.TypeRegistry.Register(Base64Decode{})
}
// Configure initializes this formatter with values from a plugin config.
func (format *Base64Decode) Configure(conf core.PluginConfigReader) {
dict := conf.GetString("Dictionary", "")
if dict == "" {
format.dictionary = base64.StdEncoding
} else {
if len(dict) != 64 {
conf.Errors.Pushf("Base64 dictionary must contain 64 characters.")
}
format.dictionary = base64.NewEncoding(dict)
}
}
// ApplyFormatter execute the formatter
func (format *Base64Decode) ApplyFormatter(msg *core.Message) error {
decoded, err := format.getDecodedContent(format.GetAppliedContent(msg))
if err != nil {
return err
}
format.SetAppliedContent(msg, decoded)
return nil
}
func (format *Base64Decode) getDecodedContent(content []byte) ([]byte, error) {
decodedLen := format.dictionary.DecodedLen(len(content))
decoded := core.MessageDataPool.Get(decodedLen)
size, err := format.dictionary.Decode(decoded, content)
if err != nil {
format.Logger.Error(err)
return nil, err
}
return decoded[:size], nil
}