commit 54cbf4cccfa1b2982dfcebf88bcdd7676d8819a1
from: Omar Polo <op@omarpolo.com>
date: Tue Oct 12 21:07:06 2021 UTC

add a simple gemini client

commit - b11fcb801f7dbbcd9d175dabdfb37f2152849600
commit + 54cbf4cccfa1b2982dfcebf88bcdd7676d8819a1
blob - /dev/null
blob + 1ecc5d408ab20f8d8457d1ebdc28afe9dd08a032 (mode 644)
--- /dev/null
+++ java/com/omarpolo/gemini/Gemini.java
@@ -0,0 +1,144 @@
+package com.omarpolo.gemini;
+
+import javax.net.ssl.*;
+import java.io.*;
+import java.net.Socket;
+import java.net.URL;
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.security.cert.X509Certificate;
+import java.util.Collections;
+import java.util.NoSuchElementException;
+import java.util.Scanner;
+
+public class Gemini {
+    public static class DummyManager extends X509ExtendedTrustManager {
+
+        @Override
+        public void checkClientTrusted(X509Certificate[] chain, String authType, Socket socket) {
+        }
+
+        @Override
+        public void checkServerTrusted(X509Certificate[] chain, String authType, Socket socket) {
+        }
+
+        @Override
+        public void checkClientTrusted(X509Certificate[] chain, String authType, SSLEngine engine) {
+        }
+
+        @Override
+        public void checkServerTrusted(X509Certificate[] chain, String authType, SSLEngine engine) {
+        }
+
+        @Override
+        public void checkClientTrusted(X509Certificate[] chain, String authType) {
+        }
+
+        @Override
+        public void checkServerTrusted(X509Certificate[] chain, String authType) {
+        }
+
+        @Override
+        public X509Certificate[] getAcceptedIssuers() {
+            return null;
+        }
+    }
+
+    public static class MalformedResponse extends Exception {
+        public MalformedResponse() {}
+        public MalformedResponse(String msg) {
+            super(msg);
+        }
+    }
+
+    public static class Response implements AutoCloseable {
+        private final BufferedReader in;
+        private final PrintWriter out;
+        private final SSLSocket sock;
+
+        private final int code;
+        private final String meta;
+
+        private Response(PrintWriter out, SSLSocket sock) throws IOException, MalformedResponse {
+            var inStream = sock.getInputStream();
+            this.in = new BufferedReader(new InputStreamReader(inStream));
+            this.out = out;
+            this.sock = sock;
+
+            var reply = in.readLine();
+            if (reply.length() > 1027) {
+                throw new MalformedResponse("reply header too long");
+            }
+
+            var s = new Scanner(new StringReader(reply));
+            try {
+                code = s.nextInt();
+                s.skip(" ");
+                meta = s.nextLine();
+            } catch (NoSuchElementException e) {
+                throw new MalformedResponse();
+            }
+        }
+
+        public int getCode() {
+            return code;
+        }
+
+        public String getMeta() {
+            return meta;
+        }
+
+        public BufferedReader body() {
+            return in;
+        }
+
+        public void close() throws IOException {
+            in.close();
+            out.close();
+            sock.close();
+        }
+    }
+
+    public static SSLSocket connect(String host, int port) throws IOException {
+        try {
+            var params = new SSLParameters();
+            params.setServerNames(Collections.singletonList(new SNIHostName(host)));
+
+            var ctx = SSLContext.getInstance("TLS");
+            ctx.init(null, new DummyManager[]{new DummyManager()}, new SecureRandom());
+            var factory = (SSLSocketFactory) ctx.getSocketFactory();
+
+            var socket = (SSLSocket) factory.createSocket(host, port);
+            socket.setSSLParameters(params);
+            socket.startHandshake();
+            return socket;
+        }
+        catch (NoSuchAlgorithmException | KeyManagementException e) {
+            throw new RuntimeException("Unexpected failure", e);
+        }
+    }
+
+    public static Response get(URL url) throws IOException, MalformedResponse {
+        int port = url.getPort();
+        if (port == -1) {
+            port = 1965;
+        }
+
+        String req = url.toString() + "\r\n";
+        return get(url.getHost(), port, req);
+    }
+
+    public static Response get(String host, int port, String req) throws IOException, MalformedResponse {
+        var sock = connect(host, port);
+
+        var outStream = sock.getOutputStream();
+        var out = new PrintWriter(
+                new BufferedWriter(new OutputStreamWriter(outStream)));
+
+        out.print(req);
+        out.flush();
+
+        return new Response(out, sock);
+    }
+}