105 lines
2.7 KiB
Go
105 lines
2.7 KiB
Go
// Copyright 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ext
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import (
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"encoding/base64"
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"github.com/google/cel-go/cel"
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"github.com/google/cel-go/checker/decls"
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"github.com/google/cel-go/interpreter/functions"
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exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
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)
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// Encoders returns a cel.EnvOption to configure extended functions for string, byte, and object
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// encodings.
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//
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// Base64.Decode
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//
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// Decodes base64-encoded string to bytes.
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//
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// This function will return an error if the string input is not base64-encoded.
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//
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// base64.decode(<string>) -> <bytes>
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//
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// Examples:
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//
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// base64.decode('aGVsbG8=') // return b'hello'
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// base64.decode('aGVsbG8') // error
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//
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// Base64.Encode
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//
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// Encodes bytes to a base64-encoded string.
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//
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// base64.encode(<bytes>) -> <string>
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//
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// Examples:
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//
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// base64.encode(b'hello') // return b'aGVsbG8='
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func Encoders() cel.EnvOption {
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return cel.Lib(encoderLib{})
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}
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type encoderLib struct{}
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func (encoderLib) CompileOptions() []cel.EnvOption {
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return []cel.EnvOption{
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cel.Declarations(
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decls.NewFunction("base64.decode",
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decls.NewOverload("base64_decode_string",
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[]*exprpb.Type{decls.String},
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decls.Bytes)),
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decls.NewFunction("base64.encode",
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decls.NewOverload("base64_encode_bytes",
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[]*exprpb.Type{decls.Bytes},
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decls.String)),
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),
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}
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}
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func (encoderLib) ProgramOptions() []cel.ProgramOption {
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wrappedBase64EncodeBytes := callInBytesOutString(base64EncodeBytes)
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wrappedBase64DecodeString := callInStrOutBytes(base64DecodeString)
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return []cel.ProgramOption{
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cel.Functions(
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&functions.Overload{
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Operator: "base64.decode",
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Unary: wrappedBase64DecodeString,
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},
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&functions.Overload{
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Operator: "base64_decode_string",
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Unary: wrappedBase64DecodeString,
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},
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&functions.Overload{
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Operator: "base64.encode",
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Unary: wrappedBase64EncodeBytes,
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},
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&functions.Overload{
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Operator: "base64_encode_bytes",
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Unary: wrappedBase64EncodeBytes,
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},
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),
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}
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}
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func base64DecodeString(str string) ([]byte, error) {
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return base64.StdEncoding.DecodeString(str)
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}
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func base64EncodeBytes(bytes []byte) (string, error) {
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return base64.StdEncoding.EncodeToString(bytes), nil
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}
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