Initial commit

iap_notify_v2.go

@@ -0,0 +1,182 @@
+package main
+
+/*
+ * 来源于： https://github.com/izniburak/appstore-notifications-go
+ * 源码中 parseJwtSignedPayload 对出错直接用了 panic，不能直接引用
+ * 修改代码以更健壮。
+ *
+ *
+ */
+
+import (
+	"crypto/ecdsa"
+	"crypto/x509"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/golang-jwt/jwt"
+)
+
+func IAP_Notify_New(payload string, appleRootCert string) (*AppStoreServerNotification, error) {
+	asn := &AppStoreServerNotification{}
+	asn.IsValid = false
+	asn.IsTest = false
+	asn.appleRootCert = appleRootCert
+
+	if err := asn.parseJwtSignedPayload(payload); err != nil {
+
+		return nil, err
+	}
+
+	return asn, nil
+}
+
+func (asn *AppStoreServerNotification) extractHeaderByIndex(payload string, index int) ([]byte, error) {
+	// get header from token
+	payloadArr := strings.Split(payload, ".")
+
+	// convert header to byte
+	headerByte, err := base64.RawStdEncoding.DecodeString(payloadArr[0])
+	if err != nil {
+		return nil, err
+	}
+
+	// bind byte to header structure
+	var header NotificationHeader
+	err = json.Unmarshal(headerByte, &header)
+	if err != nil {
+		return nil, err
+	}
+
+	// decode x.509 certificate headers to byte
+	certByte, err := base64.StdEncoding.DecodeString(header.X5c[index])
+	if err != nil {
+		return nil, err
+	}
+
+	return certByte, nil
+}
+
+func (asn *AppStoreServerNotification) verifyCertificate(certByte []byte, intermediateCert []byte) error {
+	// create certificate pool
+	roots := x509.NewCertPool()
+
+	// parse and append apple root certificate to the pool
+	ok := roots.AppendCertsFromPEM([]byte(asn.appleRootCert))
+	if !ok {
+		return errors.New("root certificate couldn't be parsed")
+	}
+
+	// parse and append intermediate x5c certificate
+	interCert, err := x509.ParseCertificate(intermediateCert)
+	if err != nil {
+		return errors.New("intermediate certificate couldn't be parsed")
+	}
+	intermediate := x509.NewCertPool()
+	intermediate.AddCert(interCert)
+
+	// parse x5c certificate
+	cert, err := x509.ParseCertificate(certByte)
+	if err != nil {
+		return err
+	}
+
+	// verify X5c certificate using app store certificate resides in opts
+	opts := x509.VerifyOptions{
+		Roots:         roots,
+		Intermediates: intermediate,
+	}
+	if _, err := cert.Verify(opts); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (asn *AppStoreServerNotification) extractPublicKeyFromPayload(payload string) (*ecdsa.PublicKey, error) {
+	// get certificate from X5c[0] header
+	certStr, err := asn.extractHeaderByIndex(payload, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	// parse certificate
+	cert, err := x509.ParseCertificate(certStr)
+	if err != nil {
+		return nil, err
+	}
+
+	// get public key
+	switch pk := cert.PublicKey.(type) {
+	case *ecdsa.PublicKey:
+		return pk, nil
+	default:
+		return nil, errors.New("appstore public key must be of type ecdsa.PublicKey")
+	}
+}
+
+func (asn *AppStoreServerNotification) parseJwtSignedPayload(payload string) error {
+	// get root certificate from x5c header
+	rootCertStr, err := asn.extractHeaderByIndex(payload, 2)
+	if err != nil {
+		return errors.New("extractHeaderByIndex error, in rootCertStr")
+	}
+
+	// get intermediate certificate from x5c header
+	intermediateCertStr, err := asn.extractHeaderByIndex(payload, 1)
+	if err != nil {
+		return errors.New("extractHeaderByIndex error, in intermediateCertStr")
+	}
+
+	// verify certificates
+	if err = asn.verifyCertificate(rootCertStr, intermediateCertStr); err != nil {
+		fmt.Printf("verifyCertificate eror: %v\n", err)
+		return errors.New("verifyCertificate eror")
+	}
+
+	// payload data
+	notificationPayload := &NotificationPayload{}
+	_, err = jwt.ParseWithClaims(payload, notificationPayload, func(token *jwt.Token) (interface{}, error) {
+		return asn.extractPublicKeyFromPayload(payload)
+	})
+	if err != nil {
+		return errors.New("ParseWithClaims NotificationPayload error")
+	}
+	asn.Payload = notificationPayload
+	asn.IsTest = asn.Payload.NotificationType == "TEST"
+
+	if asn.IsTest {
+		asn.IsValid = true
+		return nil
+	}
+
+	// transaction info
+	transactionInfo := &TransactionInfo{}
+	payload = asn.Payload.Data.SignedTransactionInfo
+	_, err = jwt.ParseWithClaims(payload, transactionInfo, func(token *jwt.Token) (interface{}, error) {
+		return asn.extractPublicKeyFromPayload(payload)
+	})
+	if err != nil {
+		return errors.New("ParseWithClaims SignedTransactionInfo error")
+	}
+	asn.TransactionInfo = transactionInfo
+
+	// renewal info
+	renewalInfo := &RenewalInfo{}
+	payload = asn.Payload.Data.SignedRenewalInfo
+	_, err = jwt.ParseWithClaims(payload, renewalInfo, func(token *jwt.Token) (interface{}, error) {
+		return asn.extractPublicKeyFromPayload(payload)
+	})
+	if err != nil {
+		return errors.New("ParseWithClaims SignedRenewalInfo error")
+	}
+	asn.RenewalInfo = renewalInfo
+
+	// valid request
+	asn.IsValid = true
+
+	return nil
+}