如果您的回调服务器被人恶意攻击了,例如恶意回调您的应用服务器,导致应用服务器收到一些非法的请求,影响正常逻辑,此时您就需要判断回调请求是否来自OSS。
在OSS回调通知及视频回调中,通知消息通过NS服务发到您的回调服务器。NS支持签名认证,具体方法如下:
用户可以通过推送请求Header中的 x-jdcloud-signing-cert-url 获取签名证书,并根据相应的方法来验证该请求是否由NS系统发出,防止恶意请求对用户造成负面影响。
在 NS 推送请求的 Header 中,Authorization 字段的值是MNS根据待签名字符串,用 SHA1-RSA 签名算法生成签名。Endpoint 可以使用公钥对签名进行验证,具体的验证方法如下:
在 NS 发送给 Endpoint 的 http 请求 Header 中,x-jdcloud-signing-cert-url 指定了签名证书的地址( Base64 编码),用户需要通过 Base64 解码,获取该签名文件 URL 地址,再从中提取出签名的公钥。
VERB + "\n" + CONTENT-MD5 + "\n" + CONTENT-TYPE + "\n" + DATE + "\n" + CanonicalizedNSHeaders + CanonicalizedResource
POST ZDgxNjY5ZjFlMDQ5MGM0YWMwMWE5ODlmZDVlYmQxYjI= text/xml;charset=utf-8 Wed, 25 May 2016 10:46:14 GMT x-jdcloud-request-id:57458276F0E3D56D7C00054B x-jdcloud-signing-cert-url:aHR0cDovL25zdGVzdC5vc3MuY24tbm9ydGgtMS5qY2xvdWRjcy5jb20veDUwOV9wdWJsaWNfY2VydGlmaWNhdGUucGVtCg== x-jdcloud-version:2015-06-06 /notifications
对Authorization 签名字段进行 Base64 Decode 解码后,使用从第一步从证书中提取的公钥对其进行解密;
比较第二步生成的待签名字符串与第三步解密的结果是否一致。如果一致,则表明请求来自NS,访问合法。 注:
1.用来签名的字符串为 UTF-8 格式;
2.签名的方法用 RFC 3447 ( http://tools.ietf.org/html/rfc3447 )中定义的 sha1WithRSAEncryption 方法;
3.Base64 是指使用 base64 算法转码文本
public class SignDemo {
private Boolean authenticate(String method, String uri, Map<String, String> headers) {
try {
//获取证书的URL
if (!headers.containsKey("x-jdcloud-signing-cert-url")) {
System.out.println("x-jdcloud-signing-cert-url Header not found");
return false;
}
String cert = headers.get("x-jdcloud-signing-cert-url");
if (cert.isEmpty()) {
System.out.println("x-jdcloud-signing-cert-url empty");
return false;
}
cert = new String(Base64.decodeBase64(cert));
System.out.println("x-jdcloud-signing-cert-url:\t" + cert);
//根据URL获取证书,并从证书中获取公钥
URL url = new URL(cert);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
DataInputStream in = new DataInputStream(conn.getInputStream());
CertificateFactory cf = CertificateFactory.getInstance("X.509");
Certificate c = cf.generateCertificate(in);
PublicKey pk = c.getPublicKey();
//获取待签名字符串
String str2sign = getSignStr(method, uri, headers);
System.out.println("String2Sign:\t" + str2sign);
//对Authorization字段做Base64解码
String signature = headers.get("Authorization");
byte[ ] decodedSign = Base64.decodeBase64(signature);
//认证
java.security.Signature signetcheck = java.security.Signature.getInstance("SHA1withRSA");
signetcheck.initVerify(pk);
signetcheck.update(str2sign.getBytes());
Boolean res = signetcheck.verify(decodedSign);
return res;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
private String getSignStr(String method, String uri, Map<String, String> headers) {
StringBuilder sb = new StringBuilder();
sb.append(method);
sb.append("\n");
sb.append(safeGetHeader(headers, "Content-md5"));
sb.append("\n");
sb.append(safeGetHeader(headers, "Content-Type"));
sb.append("\n");
sb.append(safeGetHeader(headers, "Date"));
sb.append("\n");
List<String> tmp = new ArrayList<String>();
for (Map.Entry<String, String> entry : headers.entrySet()) {
if (entry.getKey().startsWith("x-jdcloud-")) {
tmp.add(entry.getKey() + ":" + entry.getValue());
}
}
Collections.sort(tmp);
for (String kv : tmp) {
sb.append(kv);
sb.append("\n");
}
sb.append(uri);
return sb.toString();
}
private String safeGetHeader(Map<String, String> headers, String name) {
if (headers.containsKey(name)) {
return headers.get(name);
} else {
return "";
}
}
public static void main(String[ ] args) {
SignDemo sd = new SignDemo();
Map<String, String> headers = new HashMap<String, String>();
headers.put("Authorization", "Mko2Azg9fhCw8qR6G7AeAFMyzjO9qn7LDA5/t9E+6X5XURXTqBUuhpK+K55UNhrnlE2UdDkRrwDxsaDP5ajQdg==");
headers.put("Content-md5", "M2ViOTE2ZDEyOTlkODBjMjVkNzM4YjNhNWI3ZWQ1M2E=");
headers.put("Content-Type", "text/xml;charset=utf-8");
headers.put("Date", "Tue, 23 Feb 2016 09:41:06 GMT");
headers.put("x-jdcloud-request-id", "56CC2932F0E3D5BD530685CB");
headers.put("x-jdcloud-signing-cert-url", "aHR0cDovL25zdGVzdC5vc3MuY24tbm9ydGgtMS5qY2xvdWRjcy5jb20veDUwOV9wdWJsaWNfY2VydGlmaWNhdGUucGVtCg==");
Boolean res = sd.authenticate("POST", "/notifications", headers);
System.out.println("Authenticate result:" + res);
}
}