fix: 排查TCP SERVER 发布RTCM消息的断联问题

sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/rtkcluster/RtkClusterService.java

@@ -256,6 +256,21 @@ public class RtkClusterService implements ApplicationRunner {
                             }
                             // IN should not be the same socket as OUT
                             if (inConn == s) inConn = null;
+                            // Try minimal handshake if this looks like an HTTP/NTRIP GET from RTKLIB,
+                            // to keep the connection open when rtkrcv mistakenly uses ntripcli.
+                            try {
+                                String head = new String(buf, 0, Math.min(read, 256), StandardCharsets.US_ASCII);
+                                if (head.startsWith("GET ") || head.contains("RTKLIB/")) {
+                                    OutputStream os = s.getOutputStream();
+                                    String resp = head.contains("HTTP")
+                                            ? "HTTP/1.1 200 OK\r\nConnection: keep-alive\r\n\r\n"
+                                            : "ICY 200 OK\r\n\r\n";
+                                    os.write(resp.getBytes(StandardCharsets.US_ASCII));
+                                    os.flush();
+                                    LOGGER.info("[OUT:{}] handshake responded: {}", port, resp.trim());
+                                }
+                            } catch (Exception ignore) {}
+                            LOGGER.info("Endpoint {} OUT established", port);
                         }
                         String preview = new String(buf, 0, read, StandardCharsets.US_ASCII).replaceAll("\n", "\\n");
                         LOGGER.info("[OUT:{}] {}", port, preview);
@@ -264,7 +279,10 @@ public class RtkClusterService implements ApplicationRunner {
                     LOGGER.debug("Connection reader closed on {}: {}", port, e.getMessage());
                 } finally {
                     liveConns.remove(s);
-                    if (outConn == s) outConn = null;
+                    if (outConn == s) {
+                        outConn = null;
+                        LOGGER.info("Endpoint {} OUT disconnected", port);
+                    }
                     if (inConn == s) inConn = null;
                     closeQuietly(s);
                     ensureInCandidate();