121 lines
4.3 KiB
Java
121 lines
4.3 KiB
Java
package org.openautonomousconnection.webserver.utils;
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import org.openautonomousconnection.protocol.packets.v1_0_0.beta.web.WebResponsePacket;
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import org.openautonomousconnection.webserver.api.WebPageContext;
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import javax.net.ssl.HttpsURLConnection;
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import java.io.ByteArrayOutputStream;
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import java.io.InputStream;
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import java.net.URL;
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import java.nio.charset.StandardCharsets;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* Simple HTTPS -> OAC proxy helper.
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*
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* <p>Limitations:
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* <ul>
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* <li>Does not rewrite HTML/CSS URLs. If you need full offline/proxied subresources,
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* implement URL rewriting and route subresource paths through this proxy as well.</li>
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* </ul>
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*/
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public final class HttpsProxy {
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private static final int CONNECT_TIMEOUT_MS = 10_000;
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private static final int READ_TIMEOUT_MS = 25_000;
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private static final int MAX_REDIRECTS = 8;
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private HttpsProxy() {
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}
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/**
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* Fetches an HTTPS URL and returns it as a WebResponsePacket.
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*
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* @param ctx the current web page context (for optional user-agent forwarding)
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* @param url the target HTTPS URL
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* @return proxied response
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*/
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public static WebResponsePacket proxyGet(WebPageContext ctx, String url) {
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try {
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return proxyGetInternal(ctx, url, 0);
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} catch (Exception e) {
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return new WebResponsePacket(
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502,
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"text/plain; charset=utf-8",
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HeaderMaps.mutable(),
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("Bad Gateway: " + e.getClass().getName() + ": " + e.getMessage()).getBytes(StandardCharsets.UTF_8)
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);
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}
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}
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private static WebResponsePacket proxyGetInternal(WebPageContext ctx, String url, int depth) throws Exception {
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if (depth > MAX_REDIRECTS) {
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return new WebResponsePacket(
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508,
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"text/plain; charset=utf-8",
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HeaderMaps.mutable(),
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"Too many redirects".getBytes(StandardCharsets.UTF_8)
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);
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}
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URL target = new URL(url);
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HttpsURLConnection con = (HttpsURLConnection) target.openConnection();
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con.setInstanceFollowRedirects(false);
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con.setRequestMethod("GET");
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con.setConnectTimeout(CONNECT_TIMEOUT_MS);
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con.setReadTimeout(READ_TIMEOUT_MS);
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// Forward a user-agent if you have one (optional).
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String ua = null;
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if (ctx != null && ctx.request != null && ctx.request.getHeaders() != null) {
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ua = ctx.request.getHeaders().get("user-agent");
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}
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con.setRequestProperty("User-Agent", ua != null ? ua : "OAC-HttpsProxy/1.0");
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int code = con.getResponseCode();
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// Handle redirects manually to preserve content and avoid silent issues
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if (code == 301 || code == 302 || code == 303 || code == 307 || code == 308) {
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String location = con.getHeaderField("Location");
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if (location == null || location.isBlank()) {
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return new WebResponsePacket(
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502,
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"text/plain; charset=utf-8",
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HeaderMaps.mutable(),
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("Bad Gateway: redirect without Location (code=" + code + ")").getBytes(StandardCharsets.UTF_8)
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);
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}
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// Resolve relative redirects
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URL resolved = new URL(target, location);
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con.disconnect();
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return proxyGetInternal(ctx, resolved.toString(), depth + 1);
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}
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String contentType = con.getContentType();
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if (contentType == null || contentType.isBlank()) {
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contentType = "application/octet-stream";
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}
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byte[] body;
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try (InputStream in = (code >= 400 ? con.getErrorStream() : con.getInputStream())) {
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body = readAllBytes(in);
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} finally {
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con.disconnect();
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}
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return new WebResponsePacket(code, contentType, HeaderMaps.mutable(), body);
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}
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private static byte[] readAllBytes(InputStream in) throws Exception {
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if (in == null) return new byte[0];
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ByteArrayOutputStream out = new ByteArrayOutputStream(Math.max(1024, in.available()));
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byte[] buf = new byte[32 * 1024];
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int r;
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while ((r = in.read(buf)) != -1) {
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out.write(buf, 0, r);
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}
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return out.toByteArray();
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}
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}
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