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Reusable Java components for www.xqbase.com
package com.xqbase.util.servlet;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.security.GeneralSecurityException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.xqbase.util.Base64;
import com.xqbase.util.Log;
import com.xqbase.util.Numbers;
import com.xqbase.util.SocketPool;
import com.xqbase.util.Streams;
import com.xqbase.util.Strings;
public class ProxyPassServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final int RECV_MAX_CHUNK_SIZE = 4095;
private static final int RESP_MAX_SIZE = 65536;
private static final int REQ_MAX_SIZE = 4096;
private static final String HEX_DIGITS = "0123456789ABCDEF";
private static final String[] SKIP_HEADERS = {
"Access-Control-Request-Headers",
"Access-Control-Request-Method",
"Connection",
"Content-Length",
"Content-Transfer-Encoding",
// "Host",
"Keep-Alive",
// "Origin",
"Trailer",
"Transfer-Encoding",
"Upgrade",
"Via",
"X-Forwarded-For",
"X-Forwarded-Proto",
"X-Forwarded-SSL-Session-ID",
"X-Forwarded-SSL-Cipher",
"X-Forwarded-Certificates",
};
static class ClientException extends Exception {
private static final long serialVersionUID = 1L;
}
private String basePath, redirect;
private SocketPool pool;
private Map headerMap = new LinkedHashMap<>();
private Set skipHeaders = new HashSet<>();
@Override
public void init() throws ServletException {
String proxyPass = getInitParameter("proxyPass");
int timeout = Numbers.parseInt(getInitParameter("timeout"), 60000);
URL url;
try {
url = new URL(proxyPass);
} catch (IOException e) {
throw new ServletException(e);
}
int port = url.getPort();
port = port < 0 ? url.getDefaultPort() : port;
pool = new SocketPool(url.getHost(), port, "https".equals(url.getProtocol()), timeout);
basePath = url.getPath();
redirect = getInitParameter("redirect");
Enumeration en = getInitParameterNames();
while (en.hasMoreElements()) {
String name = (String) en.nextElement();
if (name.startsWith("Header-")) {
headerMap.put(name.substring(7), getInitParameter(name));
}
}
for (String header : SKIP_HEADERS) {
skipHeaders.add(header.toUpperCase());
}
for (String header : headerMap.keySet()) {
skipHeaders.add(header.toUpperCase());
}
}
@Override
public void destroy() {
pool.close();
}
private static void write(OutputStream out, String s) throws IOException {
out.write(s.getBytes(StandardCharsets.ISO_8859_1));
}
private static void writeln(OutputStream out) throws IOException {
out.write('\r');
out.write('\n');
}
private static void writeHeader(OutputStream out, String key,
String value) throws IOException {
write(out, key);
out.write(':');
out.write(' ');
write(out, value);
writeln(out);
}
private static void copyResponse(InputStream inSocket, OutputStream outResp,
byte[] buffer, int length) throws ClientException, IOException {
int bytesToRead = length;
while (bytesToRead > 0) {
int bytesRead = inSocket.read(buffer, 0,
Math.min(RESP_MAX_SIZE, bytesToRead));
if (bytesRead < 0) {
throw new IOException("Connection Lost");
}
if (bytesRead == 0) {
throw new IOException("Zero Bytes Read");
}
bytesToRead -= bytesRead;
try {
outResp.write(buffer, 0, bytesRead);
} catch (IOException e) {
// Close if too much left
if (bytesToRead > RESP_MAX_SIZE) {
throw new ClientException();
}
}
}
}
private static final int METHOD_HEAD = 1;
private static final List METHOD_VALUE = Arrays.asList("GET", "HEAD");
@SuppressWarnings("resource")
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) {
String query = req.getQueryString();
String fullPath = basePath + req.getPathInfo() +
(Strings.isEmpty(query) ? "" : "?" + query);
String method = req.getMethod();
int methodType = METHOD_VALUE.indexOf(method);
try (SocketPool.Entry socketEntry = pool.borrow()) {
// Request Head
Socket socket = socketEntry.getObject();
BufferedOutputStream outSocket = new
BufferedOutputStream(socket.getOutputStream());
write(outSocket, method);
outSocket.write(' ');
write(outSocket, fullPath);
write(outSocket, " HTTP/1.1");
writeln(outSocket);
Enumeration en = req.getHeaderNames();
while (en.hasMoreElements()) {
String key = (String) en.nextElement();
if (skipHeaders.contains(key.toUpperCase())) {
continue;
}
Enumeration en2 = req.getHeaders(key);
while (en2.hasMoreElements()) {
String value = (String) en2.nextElement();
if (key.equalsIgnoreCase("Destination")) {
// See http://httpd.apache.org/docs/current/mod/mod_headers.html, Example 5
if (req.isSecure() && value.startsWith("https:")) {
value = "http:" + value.substring(6);
}
}
writeHeader(outSocket, key, value);
}
}
for (Map.Entry entry : headerMap.entrySet()) {
writeHeader(outSocket, entry.getKey(), entry.getValue());
}
writeHeader(outSocket, "X-Forwarded-For", req.getRemoteAddr());
writeHeader(outSocket, "X-Forwarded-Proto", req.getScheme());
Object sslSessionId = req.getAttribute("javax.servlet.request.ssl_session_id");
if (sslSessionId instanceof String) {
writeHeader(outSocket, "X-Forwarded-SSL-Session-ID", (String) sslSessionId);
}
Object cipherSuite = req.getAttribute("javax.servlet.request.cipher_suite");
if (cipherSuite instanceof String) {
writeHeader(outSocket, "X-Forwarded-SSL-Cipher", (String) cipherSuite);
}
Object certificates = req.getAttribute("javax.servlet.request.X509Certificate");
if (certificates instanceof X509Certificate[]) {
writeHeader(outSocket, "X-Forwarded-Certificates",
Base64.encode(CertificateFactory.
getInstance("X509").generateCertPath(Arrays.
asList((X509Certificate[]) certificates)).getEncoded("PKCS7")));
}
writeHeader(outSocket, "Connection", "Keep-Alive");
// Request Body
int contentLength = req.getContentLength();
if (contentLength > 0) {
writeHeader(outSocket, "Content-Length", "" + contentLength);
writeln(outSocket);
// Streams.copy(req.getInputStream(), outSocket);
// Should throw ClientException when req.getInputStream() broken
InputStream in = req.getInputStream();
byte[] buffer = new byte[REQ_MAX_SIZE];
while (true) {
int bytesRead;
try {
bytesRead = in.read(buffer);
} catch (IOException e) {
throw new ClientException();
}
if (bytesRead <= 0) {
break;
}
outSocket.write(buffer, 0, bytesRead);
}
} else if (methodType >= 0) {
writeln(outSocket);
} else if (contentLength == 0) {
writeHeader(outSocket, "Content-Length", "0");
writeln(outSocket);
} else {
// Request Body (Chunked)
writeHeader(outSocket, "Transfer-Encoding", "chunked");
InputStream inReq = req.getInputStream();
byte[] buffer = new byte[RECV_MAX_CHUNK_SIZE + 7];
buffer[3] = '\r';
buffer[4] = '\n';
int bytesRead;
while ((bytesRead = inReq.read(buffer, 5, RECV_MAX_CHUNK_SIZE)) > 0) {
buffer[0] = (byte) HEX_DIGITS.charAt(bytesRead / 256);
buffer[1] = (byte) HEX_DIGITS.charAt(bytesRead / 16 % 16);
buffer[2] = (byte) HEX_DIGITS.charAt(bytesRead % 16);
buffer[bytesRead + 5] = '\r';
buffer[bytesRead + 6] = '\n';
outSocket.write(buffer, 0, bytesRead + 7);
}
outSocket.write('0');
writeln(outSocket);
writeln(outSocket);
}
outSocket.flush();
// Response Head
BufferedInputStream inSocket = new
BufferedInputStream(socket.getInputStream());
boolean http10 = false, close = false;
int status = 0;
StringBuilder sb = new StringBuilder();
contentLength = Integer.MIN_VALUE;
while (true) {
int b = inSocket.read();
if (b < 0) {
throw new IOException("Connection Lost");
}
if (b == '\r') {
continue;
}
if (b != '\n') {
sb.append((char) b);
continue;
}
if (sb.length() == 0) {
if (status == HttpServletResponse.SC_CONTINUE) {
status = 0;
continue;
}
resp.setStatus(status);
break;
}
if (status == 0) {
String[] ss = sb.toString().split(" ");
if (ss.length < 2) {
throw new IOException("Response Error: [" + sb + "]");
}
status = Numbers.parseInt(ss[1]);
if (ss[0].toUpperCase().equals("HTTP/1.0")) {
http10 = true;
}
} else if (status != HttpServletResponse.SC_CONTINUE) {
int index = sb.indexOf(": ");
if (index >= 0) {
String key = sb.substring(0, index);
String value = sb.substring(index + 2);
if (skipHeaders.contains(key.toUpperCase())) {
if (key.equalsIgnoreCase("Content-Length")) {
contentLength = Numbers.parseInt(value);
} else if (key.equalsIgnoreCase("Transfer-Encoding")) {
if (value.equalsIgnoreCase("chunked")) {
contentLength = -1;
} else {
Log.w("Transfer-Encoding: [" + value + "]");
}
} else if (!close) {
if (key.equalsIgnoreCase("Connection")) {
close = value.equalsIgnoreCase("close");
} else if (key.equalsIgnoreCase("Keep-Alive")) {
close = true;
}
}
} else {
resp.addHeader(key, value);
}
}
}
sb.setLength(0);
}
if (contentLength == Integer.MIN_VALUE) {
if (close && methodType != METHOD_HEAD) {
http10 = true;
} else {
contentLength = 0;
}
}
// Response Body
OutputStream outResp = resp.getOutputStream();
if (http10) {
// For HTTP/1.0 response, read from stream until connection lost
Streams.copy(inSocket, outResp, true);
socketEntry.setValid(false);
return;
}
if (contentLength == 0 || methodType == METHOD_HEAD) {
resp.setContentLength(contentLength);
socketEntry.setValid(!close);
return;
}
byte[] buffer = new byte[RESP_MAX_SIZE];
if (contentLength > 0) {
resp.setContentLength(contentLength);
copyResponse(inSocket, outResp, buffer, contentLength);
socketEntry.setValid(!close);
return;
}
/* Response Body (Chunked)
* >=0: waiting size and CRLF
* -1: waiting next block (CRLF)
* -2: waiting terminator (CRLF)
*/
int chunkSize = 0;
while (true) {
int b = inSocket.read();
if (b < 0) {
throw new IOException("Connection Lost");
}
if (chunkSize < 0) {
if (b == '\n') {
if (chunkSize == -2) {
break;
}
chunkSize = 0;
}
} else if (b == '\n') {
if (chunkSize == 0) {
chunkSize = -2;
} else {
copyResponse(inSocket, outResp, buffer, chunkSize);
chunkSize = -1;
}
} else {
b = HEX_DIGITS.indexOf(Character.toUpperCase(b));
if (b >= 0) {
chunkSize = chunkSize * 16 + b;
}
}
}
socketEntry.setValid(!close);
} catch (ClientException e) {
// Ignored
} catch (IOException | GeneralSecurityException e) {
try {
if (redirect == null) {
resp.sendError(HttpServletResponse.SC_BAD_GATEWAY);
} else {
resp.sendRedirect(redirect);
}
} catch (IOException e_) {/**/}
Log.w(e.getMessage());
}
}
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