break
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构建并部署到测试环境（无 SSH） / build-and-deploy (push) Successful in 8m26s
86 lines
3.3 KiB
Go
86 lines
3.3 KiB
Go
package wecom
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/sha1"
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"crypto/subtle"
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"encoding/base64"
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"encoding/binary"
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"encoding/hex"
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"sort"
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"strings"
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"github.com/break/junhong_cmp_fiber/pkg/errors"
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)
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// CallbackCrypto 实现企微回调要求的 SHA-1 签名校验和 AES-256-CBC 解密。
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type CallbackCrypto struct {
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token string
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aesKey []byte
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receiveID string
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}
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// NewCallbackCrypto 创建企业微信回调加密器。
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func NewCallbackCrypto(token, encodingAESKey, receiveID string) (*CallbackCrypto, error) {
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key, err := base64.StdEncoding.DecodeString(strings.TrimSpace(encodingAESKey) + "=")
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if err != nil || len(key) != 32 || strings.TrimSpace(token) == "" || strings.TrimSpace(receiveID) == "" {
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return nil, errors.New(errors.CodeWeComCredentialInvalid, "企业微信回调 Token、EncodingAESKey 或 receiveid 无效")
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}
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return &CallbackCrypto{token: token, aesKey: key, receiveID: receiveID}, nil
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}
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// VerifyAndDecrypt 校验签名并解密企业微信回调密文。
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func (c *CallbackCrypto) VerifyAndDecrypt(signature, timestamp, nonce, encrypted string) ([]byte, error) {
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if c == nil || !c.validSignature(signature, timestamp, nonce, encrypted) {
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return nil, errors.New(errors.CodeUnauthorized, "企业微信回调签名无效")
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}
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ciphertext, err := base64.StdEncoding.DecodeString(encrypted)
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if err != nil || len(ciphertext) == 0 || len(ciphertext)%aes.BlockSize != 0 {
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return nil, errors.New(errors.CodeInvalidParam, "企业微信回调密文无效")
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}
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block, err := aes.NewCipher(c.aesKey)
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if err != nil {
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return nil, errors.Wrap(errors.CodeInternalError, err, "初始化企业微信回调解密器失败")
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}
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plaintext := make([]byte, len(ciphertext))
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cipher.NewCBCDecrypter(block, c.aesKey[:aes.BlockSize]).CryptBlocks(plaintext, ciphertext)
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plaintext, err = removePKCS7Padding(plaintext)
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if err != nil || len(plaintext) < 20 {
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return nil, errors.New(errors.CodeInvalidParam, "企业微信回调填充无效")
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}
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messageLength := int(binary.BigEndian.Uint32(plaintext[16:20]))
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if messageLength < 0 || 20+messageLength > len(plaintext) {
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return nil, errors.New(errors.CodeInvalidParam, "企业微信回调消息长度无效")
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}
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message := plaintext[20 : 20+messageLength]
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receiveID := plaintext[20+messageLength:]
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if subtle.ConstantTimeCompare(receiveID, []byte(c.receiveID)) != 1 {
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return nil, errors.New(errors.CodeUnauthorized, "企业微信回调 receiveid 不匹配")
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}
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return append([]byte(nil), message...), nil
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}
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func (c *CallbackCrypto) validSignature(signature, timestamp, nonce, encrypted string) bool {
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parts := []string{c.token, timestamp, nonce, encrypted}
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sort.Strings(parts)
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hash := sha1.Sum([]byte(strings.Join(parts, "")))
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expected := hex.EncodeToString(hash[:])
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return subtle.ConstantTimeCompare([]byte(strings.ToLower(signature)), []byte(expected)) == 1
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}
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func removePKCS7Padding(value []byte) ([]byte, error) {
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if len(value) == 0 {
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return nil, errors.New(errors.CodeInvalidParam)
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}
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padding := int(value[len(value)-1])
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if padding <= 0 || padding > 32 || padding > len(value) {
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return nil, errors.New(errors.CodeInvalidParam)
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}
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if !bytes.Equal(value[len(value)-padding:], bytes.Repeat([]byte{byte(padding)}, padding)) {
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return nil, errors.New(errors.CodeInvalidParam)
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}
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return value[:len(value)-padding], nil
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}
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