go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/tokenserver/appengine/impl/utils/pem.go (about)

     1  // Copyright 2016 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package utils
    16  
    17  import (
    18  	"encoding/pem"
    19  	"fmt"
    20  )
    21  
    22  // ParsePEM takes pem-encoded block and decodes it, checking the header.
    23  func ParsePEM(data, header string) ([]byte, error) {
    24  	block, rest := pem.Decode([]byte(data))
    25  	if len(rest) != 0 || block == nil {
    26  		return nil, fmt.Errorf("not a valid %q PEM", header)
    27  	}
    28  	if block.Type != header {
    29  		return nil, fmt.Errorf("expecting %q, got %q", header, block.Type)
    30  	}
    31  	return block.Bytes, nil
    32  }
    33  
    34  // DumpPEM transforms block to pem-encoding.
    35  //
    36  // Reverse of ParsePEM.
    37  func DumpPEM(data []byte, header string) string {
    38  	return string(pem.EncodeToMemory(&pem.Block{
    39  		Type:  header,
    40  		Bytes: data,
    41  	}))
    42  }