JSP for Discourse SSO

因为JAVA的Base64实现和Ruby不同，在使用SSO时会有异常，根据meta.discoursecn.org管理员的指点及资料查阅和代码分析，实现如下：

<%@ page contentType="text/html; charset=utf-8" %><%@ page import="org.apache.commons.codec.binary.Base64" %><%@ page import="org.apache.commons.codec.binary.Hex" %><%@ page import="javax.crypto.Mac" %><%@ page import="javax.crypto.spec.SecretKeySpec" %><%@ page import="java.io.UnsupportedEncodingException" %><%@ page import="java.net.URLDecoder" %><%@ page import="java.net.URLEncoder" %><%@ page import="java.security.InvalidKeyException" %><%@ page import="java.security.NoSuchAlgorithmException" %><%    response.setHeader("Pragma", "no-cache");    response.setDateHeader("Expires", -1);    Info info = (Info) session.getAttribute("Info");    if (info == null) {        response.sendRedirect("login.html");        return;    }    String key = "yourssosecret";    String payload = request.getParameter("sso");    String sig = request.getParameter("sig");    if (payload == null || sig == null) {        response.getWriter().println("error parameter");        return;    }    if (!checksum(key, payload).equals(sig)) {        response.getWriter().println("checksum failed");        return;    }    String urlDecode = URLDecoder.decode(payload, "UTF-8");    String nonce = new String(Base64.decodeBase64(urlDecode));    String urlEncode = nonce            + "&name=" + URLEncoder.encode(info.name, "UTF-8")            + "&username=" + URLEncoder.encode(info.nickname, "UTF-8")            + "&email=" + URLEncoder.encode(info.email, "UTF-8")            + "&external_id=" + URLEncoder.encode(info.id + "", "UTF-8");    String urlBase64 = new String(Base64.encodeBase64(urlEncode.getBytes("UTF-8")));    int length = 0;    int maxLength = urlBase64.length();    final int STEP = 60;    String urlBase64Encode = "";    while (length < maxLength) {        urlBase64Encode += urlBase64.substring(length, length + STEP < maxLength ? length + STEP : maxLength) + "\n";        length += STEP;    }    response.sendRedirect("http://yoursite.com/session/sso_login?sso=" + URLEncoder.encode(urlBase64Encode, "UTF-8") + "&sig=" + checksum(key, urlBase64Encode));%><%!    String checksum(String macKey, String macData) throws NoSuchAlgorithmException, UnsupportedEncodingException, InvalidKeyException {        Mac mac = Mac.getInstance("HmacSHA256");        byte[] keyBytes = macKey.getBytes("UTF-8");        byte[] dataBytes = macData.getBytes("UTF-8");        SecretKeySpec secretKey = new SecretKeySpec(keyBytes, "HmacSHA256");        mac.init(secretKey);        byte[] doFinal = mac.doFinal(dataBytes);        byte[] hexBytes = new Hex().encode(doFinal);        return new String(hexBytes);    }%>