src/org/cacert/gigi/output/Form.java

   1 package org.cacert.gigi.output;
   2
   3 import java.io.PrintWriter;
   4 import java.util.Map;
   5
   6 import javax.servlet.ServletRequest;
   7 import javax.servlet.http.HttpServletRequest;
   8 import javax.servlet.http.HttpSession;
   9
  10 import org.cacert.gigi.Language;
  11 import org.cacert.gigi.pages.Page;
  12 import org.cacert.gigi.util.RandomToken;
  13
  14 public abstract class Form implements Outputable {
  15         public static final String CSRF_FIELD = "csrf";
  16         String csrf;
  17
  18         public Form(HttpServletRequest hsr) {
  19                 csrf = RandomToken.generateToken(32);
  20                 HttpSession hs = hsr.getSession();
  21                 hs.setAttribute("form/" + getClass().getName() + "/" + csrf, this);
  22
  23         }
  24
  25         public abstract boolean submit(PrintWriter out, HttpServletRequest req);
  26
  27         @Override
  28         public final void output(PrintWriter out, Language l, Map<String, Object> vars) {
  29                 out.println("<form method='POST' autocomplete='off'>");
  30                 outputContent(out, l, vars);
  31                 out.print("<input type='hidden' name='" + CSRF_FIELD + "' value='");
  32                 out.print(getCSRFToken());
  33                 out.println("'></form>");
  34         }
  35
  36         protected abstract void outputContent(PrintWriter out, Language l, Map<String, Object> vars);
  37
  38         protected void outputError(PrintWriter out, ServletRequest req, String text) {
  39                 out.print("<div>");
  40                 out.print(Page.translate(req, text));
  41                 out.println("</div>");
  42         }
  43
  44         protected String getCSRFToken() {
  45                 return csrf;
  46         }
  47
  48         protected void checkCSRF(HttpServletRequest req) {
  49                 if (!csrf.equals(req.getParameter(CSRF_FIELD))) {
  50                         throw new CSRFError();
  51                 }
  52         }
  53
  54         public static <T extends Form> T getForm(HttpServletRequest req, Class<T> target) {
  55                 String csrf = req.getParameter(CSRF_FIELD);
  56                 if (csrf == null) {
  57                         throw new CSRFError();
  58                 }
  59                 HttpSession hs = req.getSession();
  60                 if (hs == null) {
  61                         throw new CSRFError();
  62                 }
  63                 Form f = (Form) hs.getAttribute("form/" + target.getName() + "/" + csrf);
  64                 if (f == null) {
  65                         throw new CSRFError();
  66                 }
  67                 return (T) f;
  68         }
  69
  70         public static class CSRFError extends Error {
  71
  72         }
  73 }