Program: 82807
Project: 82807
Buggy source:
private Response respond(Map<String,String> headers,IHTTPSession session,String uri){
  uri=uri.trim().replace(File.separatorChar,'/');
  if (uri.indexOf('?') >= 0) {
    uri=uri.substring(0,uri.indexOf('?'));
  }
  if (uri.startsWith("String_Node_Str") || uri.endsWith("String_Node_Str") || uri.contains("String_Node_Str")) {
    return getForbiddenResponse("String_Node_Str");
  }
  boolean canServeUri=false;
  File homeDir=null;
  List<File> roots=getRootDirs();
  for (int i=0; !canServeUri && i < roots.size(); i++) {
    homeDir=roots.get(i);
    canServeUri=canServeUri(uri,homeDir);
  }
  if (!canServeUri) {
    return getNotFoundResponse();
  }
  File f=new File(homeDir,uri);
  if (f.isDirectory() && !uri.endsWith("String_Node_Str")) {
    uri+="String_Node_Str";
    Response res=createResponse(Response.Status.REDIRECT,NanoHTTPD.MIME_HTML,"String_Node_Str" + uri + "String_Node_Str"+ uri+ "String_Node_Str");
    res.addHeader("String_Node_Str",uri);
    return res;
  }
  if (f.isDirectory()) {
    String indexFile=findIndexFileInDirectory(f);
    if (indexFile == null) {
      if (f.canRead()) {
        return createResponse(Response.Status.OK,NanoHTTPD.MIME_HTML,listDirectory(uri,f));
      }
 else {
        return getForbiddenResponse("String_Node_Str");
      }
    }
 else {
      return respond(headers,session,uri + indexFile);
    }
  }
  String mimeTypeForFile=getMimeTypeForFile(uri);
  WebServerPlugin plugin=mimeTypeHandlers.get(mimeTypeForFile);
  Response response=null;
  if (plugin != null) {
    response=plugin.serveFile(uri,headers,session,f,mimeTypeForFile);
    if (response != null && response instanceof InternalRewrite) {
      InternalRewrite rewrite=(InternalRewrite)response;
      return respond(rewrite.getHeaders(),session,rewrite.getUri());
    }
  }
 else {
    response=serveFile(uri,headers,f,mimeTypeForFile);
  }
  return response != null ? response : getNotFoundResponse();
}

Fixed version (ground truth):
private Response respond(Map<String,String> headers,IHTTPSession session,String uri){
  uri=uri.trim().replace(File.separatorChar,'/');
  if (uri.indexOf('?') >= 0) {
    uri=uri.substring(0,uri.indexOf('?'));
  }
  if (uri.startsWith("String_Node_Str") || uri.endsWith("String_Node_Str") || uri.contains("String_Node_Str")) {
    return getForbiddenResponse("String_Node_Str");
  }
  boolean canServeUri=false;
  File homeDir=null;
  List<File> roots=getRootDirs();
  for (int i=0; !canServeUri && i < roots.size(); i++) {
    homeDir=roots.get(i);
    canServeUri=canServeUri(uri,homeDir);
  }
  if (!canServeUri) {
    return getNotFoundResponse();
  }
  File f=new File(homeDir,uri);
  if (f.isDirectory() && !uri.endsWith("String_Node_Str")) {
    uri+="String_Node_Str";
    Response res=createResponse(Response.Status.REDIRECT,NanoHTTPD.MIME_HTML,"String_Node_Str" + uri + "String_Node_Str"+ uri+ "String_Node_Str");
    res.addHeader("String_Node_Str",uri);
    return res;
  }
  if (f.isDirectory()) {
    String indexFile=findIndexFileInDirectory(f);
    if (indexFile == null) {
      if (f.canRead()) {
        return createResponse(Response.Status.OK,NanoHTTPD.MIME_HTML,listDirectory(uri,f));
      }
 else {
        return getForbiddenResponse("String_Node_Str");
      }
    }
 else {
      return respond(headers,session,uri + indexFile);
    }
  }
  String mimeTypeForFile=getMimeTypeForFile(uri);
  WebServerPlugin plugin=mimeTypeHandlers.get(mimeTypeForFile);
  Response response=null;
  if (plugin != null && plugin.canServeUri(uri,f)) {
    response=plugin.serveFile(uri,headers,session,f,mimeTypeForFile);
    if (response != null && response instanceof InternalRewrite) {
      InternalRewrite rewrite=(InternalRewrite)response;
      return respond(rewrite.getHeaders(),session,rewrite.getUri());
    }
  }
 else {
    response=serveFile(uri,headers,f,mimeTypeForFile);
  }
  return response != null ? response : getNotFoundResponse();
}