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validator.go
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/
validator.go
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/*
* Copyright (c) 2022 eBay 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.
*
This package contains required helper functions
*/
package helper
import (
"crypto/ecdsa"
"crypto/sha1"
"crypto/sha256"
"crypto/x509"
"encoding/base64"
"encoding/hex"
"encoding/json"
"encoding/pem"
"fmt"
"strings"
constants "github.com/ebay/event-notification-golang-sdk.git/lib/constants"
pojo "github.com/ebay/event-notification-golang-sdk.git/lib/pojo"
service "github.com/ebay/event-notification-golang-sdk.git/lib/service"
)
//Get XeBay Signature header takes in signature decode using base64 and returns it
//Returns base64 decoded signature
//Input
// signatureHeader - base64 encoded signature
//Returns
// base64 decoded signature
func getXeBaySignatureHeader(signatureHeader string) *pojo.XeBaySignatureHeader {
rawDecodedText, err := base64.StdEncoding.DecodeString(signatureHeader)
if err != nil {
panic(err)
}
var signature pojo.XeBaySignatureHeader
json.Unmarshal([]byte(rawDecodedText), &signature)
return &signature
}
//The format key function convert key by adding newline before/after comments
//Input
// key - unformatted key
//Returns
// key - formatted key
func formatKey(key string) string {
key = strings.Replace(key, constants.KeyStart, fmt.Sprintf("%s\n", constants.KeyStart), 1)
key = strings.Replace(key, constants.KeyEnd, fmt.Sprintf("\n%s", constants.KeyEnd), 1)
return key
}
//ValidateSignature is to validate signature used in request
//Returns string Success/Error
//Input
// message - message details
// signatureHeader - base64 encoded signature
// config - specific custom environment
//Returns
// string Success/Error
func ValidateSignature(message *pojo.Message, signatureHeader string, config *pojo.CustomEnvironment) string {
// Base64 decode the signatureHeader and convert to JSON
xeBaySignature := getXeBaySignatureHeader(signatureHeader)
// // Get the public key
publicKey := service.GetPublicKey(xeBaySignature.Kid, config)
var pubPEMData = []byte(formatKey(publicKey.Key))
block, _ := pem.Decode(pubPEMData)
if block == nil {
fmt.Println("Invalid PEM Block")
return constants.Error
}
key, err := x509.ParsePKIXPublicKey(block.Bytes)
if err != nil {
fmt.Println(err)
return constants.Error
}
pubKey := key.(*ecdsa.PublicKey)
signature, err := base64.StdEncoding.DecodeString(xeBaySignature.Signature)
if err != nil {
fmt.Println(err)
return constants.Error
}
byteArr, err := json.Marshal(message)
if err != nil {
fmt.Println(err)
return constants.Error
}
hash := sha1.Sum(byteArr)
success := ecdsa.VerifyASN1(pubKey, hash[:], signature)
if success != true {
fmt.Println(err)
return constants.Error
}
return constants.Success
}
//GenerateChallengeResponse is used to generate challenge response for given challenge code
//Input
// challengeCode - challengeCode to be processed
// config - config details for processing
//Returns
// challenge response
func GenerateChallengeResponse(challengeCode string, config *pojo.Config) string {
hasher := sha256.New()
hasher.Write([]byte(challengeCode))
hasher.Write([]byte(config.VerificationToken))
hasher.Write([]byte(config.Endpoint))
digest := hasher.Sum(nil)
digestStr := hex.EncodeToString(digest)
return digestStr
}