// CgiServlet - runs CGI programs
//
// Copyright (C)1996,1998 by Jef Poskanzer <jef@acme.com>. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/

package Acme.Serve;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.StringTokenizer;
import java.util.Vector;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/// Runs CGI programs.
// <P>
// Note: although many implementations of CGI set the working directory of
// the subprocess to be the directory containing the executable file, the
// CGI spec actually says nothing about the working directory.  Since
// Java has no method for setting the working directory, this implementation
// does not set it.
// <P>
// <A HREF="/resources/classes/Acme/Serve/CgiServlet.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.Z">Fetch the entire Acme package.</A>
// <P>
// @see Acme.Serve.Serve

public class CgiServlet extends HttpServlet {

	// / Returns a string containing information about the author, version, and
	// copyright of the servlet.
	public String getServletInfo() {
		return "runs CGI programs";
	}

	// / Services a single request from the client.
	// @param req the servlet request
	// @param req the servlet response
	// @exception ServletException when an exception has occurred
	public void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
		if (!(req.getMethod().equalsIgnoreCase("get") || req.getMethod().equalsIgnoreCase("post"))) {
			res.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED);
			return;
		}
		dispatchPathname(req, res, getServletContext().getRealPath(req.getServletPath() + req.getPathInfo()));
	}

	private void dispatchPathname(HttpServletRequest req, HttpServletResponse res, String path) throws IOException {
		if (new File(path).exists())
			serveFile(req, res, path);
		else
			res.sendError(HttpServletResponse.SC_NOT_FOUND);
	}

	private void serveFile(HttpServletRequest req, HttpServletResponse res, String path) throws IOException {
		String queryString = req.getQueryString();
		int contentLength = req.getContentLength();
		int c;

		log("running " + path + "?" + queryString);

		// Make argument list.
		String argList[] = (path + (queryString != null && queryString.indexOf("=") == -1 ? "+" + queryString : ""))
				.split("\\+"); /* 1.4 */

		// Make environment list.
		Vector envVec = new Vector();
		envVec.addElement(makeEnv("PATH", "/usr/local/bin:/usr/ucb:/bin:/usr/bin"));
		envVec.addElement(makeEnv("GATEWAY_INTERFACE", "CGI/1.1"));
		envVec.addElement(makeEnv("SERVER_SOFTWARE", getServletContext().getServerInfo()));
		envVec.addElement(makeEnv("SERVER_NAME", req.getServerName()));
		envVec.addElement(makeEnv("SERVER_PORT", Integer.toString(req.getServerPort())));
		envVec.addElement(makeEnv("REMOTE_ADDR", req.getRemoteAddr()));
		envVec.addElement(makeEnv("REMOTE_HOST", req.getRemoteHost()));
		envVec.addElement(makeEnv("REQUEST_METHOD", req.getMethod()));
		if (contentLength != -1)
			envVec.addElement(makeEnv("CONTENT_LENGTH", Integer.toString(contentLength)));
		if (req.getContentType() != null)
			envVec.addElement(makeEnv("CONTENT_TYPE", req.getContentType()));
		envVec.addElement(makeEnv("SCRIPT_NAME", req.getServletPath()));
		if (req.getPathInfo() != null)
			envVec.addElement(makeEnv("PATH_INFO", req.getPathInfo()));
		if (req.getPathTranslated() != null)
			envVec.addElement(makeEnv("PATH_TRANSLATED", req.getPathTranslated()));
		if (queryString != null)
			envVec.addElement(makeEnv("QUERY_STRING", queryString));
		envVec.addElement(makeEnv("SERVER_PROTOCOL", req.getProtocol()));
		if (req.getRemoteUser() != null)
			envVec.addElement(makeEnv("REMOTE_USER", req.getRemoteUser()));
		if (req.getAuthType() != null)
			envVec.addElement(makeEnv("AUTH_TYPE", req.getAuthType()));
		Enumeration hnEnum = req.getHeaderNames();
		while (hnEnum.hasMoreElements()) {
			String name = (String) hnEnum.nextElement();
			String value = req.getHeader(name);
			if (value == null)
				value = "";
			envVec.addElement(makeEnv("HTTP_" + name.toUpperCase().replace('-', '_'), value));
		}
		String envList[] = makeList(envVec);

		// Start the command.
		Process proc = Runtime.getRuntime().exec(argList, envList);

		try {
			// If it's a POST, copy the request data to the process.
			if (req.getMethod().equalsIgnoreCase("post")) {
				InputStream reqIn = req.getInputStream();
				OutputStream procOut = proc.getOutputStream();
				for (int i = 0; i < contentLength; ++i) {
					c = reqIn.read();
					if (c == -1)
						break;
					procOut.write(c);
				}
				procOut.close();
			}

			// Now read the response from the process.
			BufferedReader procIn = new BufferedReader(new InputStreamReader(proc.getInputStream()));
			OutputStream resOut = res.getOutputStream();
			// Some of the headers have to be intercepted and handled.
			boolean firstLine = true;
			while (true) {
				String line = procIn.readLine();
				if (line == null)
					break;
				line = line.trim();
				if (line.equals(""))
					break;
				int colon = line.indexOf(":");
				if (colon == -1) {
					// No colon. If it's the first line, parse it for status.
					if (firstLine) {
						StringTokenizer tok = new StringTokenizer(line, " ");
						try {
							switch (tok.countTokens()) {
							case 2:
								tok.nextToken();
								res.setStatus(Integer.parseInt(tok.nextToken()));
								break;
							case 3:
								tok.nextToken();
								res.setStatus(Integer.parseInt(tok.nextToken()), tok.nextToken());
								break;
							}
						} catch (NumberFormatException ignore) {
						}
					} else {
						// No colon and it's not the first line? Ignore.
					}
				} else {
					// There's a colon. Check for certain special headers.
					String name = line.substring(0, colon);
					String value = line.substring(colon + 1).trim();
					if (name.equalsIgnoreCase("Status")) {
						StringTokenizer tok = new StringTokenizer(value, " ");
						try {
							switch (tok.countTokens()) {
							case 1:
								res.setStatus(Integer.parseInt(tok.nextToken()));
								break;
							case 2:
								res.setStatus(Integer.parseInt(tok.nextToken()), tok.nextToken());
								break;
							}
						} catch (NumberFormatException ignore) {
						}
					} else if (name.equalsIgnoreCase("Content-type")) {
						res.setContentType(value);
					} else if (name.equalsIgnoreCase("Content-length")) {
						try {
							res.setContentLength(Integer.parseInt(value));
						} catch (NumberFormatException ignore) {
						}
					} else if (name.equalsIgnoreCase("Location")) {
						res.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
						res.setHeader(name, value);
					} else {
						// Not a special header. Just set it.
						res.setHeader(name, value);
					}
				}
			}
			// Copy the rest of the data uninterpreted.
			Acme.Utils.copyStream(procIn, resOut, null);
			procIn.close();
			resOut.close();
		} catch (IOException e) {
			// res.sendError( HttpServletResponse.SC_INTERNAL_SERVER_ERROR );
			// There's some weird bug in Java, when reading from a Process
			// you get a spurious IOException. We have to ignore it.
		}
	}

	private static String makeEnv(String name, String value) {
		return name + "=" + value;
	}

	private static String[] makeList(Vector vec) {
		String list[] = new String[vec.size()];
		for (int i = 0; i < vec.size(); ++i)
			list[i] = (String) vec.elementAt(i);
		return list;
	}

}