#3: ClientDetector (#8)

vpn-router-bootstrap/src/main/resources/application.yml

@@ -1,2 +1,4 @@
 storage:
   clients-file-path: ${HOME}/vpn-router/storage/clients.yml
+network:
+  address: 192.168.0.0/24

vpn-router-core/src/main/java/vpnrouter/core/infrastructure/shell/NetworkProperties.java

@@ -0,0 +1,10 @@
+package vpnrouter.core.infrastructure.shell;
+
+import lombok.Data;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+@Data
+@ConfigurationProperties("network")
+public class NetworkProperties {
+    private final String address;
+}

vpn-router-core/src/main/java/vpnrouter/core/infrastructure/shell/RealClientDetector.java

@@ -0,0 +1,26 @@
+package vpnrouter.core.infrastructure.shell;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.context.annotation.Primary;
+import org.springframework.context.annotation.Profile;
+import org.springframework.stereotype.Component;
+import vpnrouter.core.service.client.detection.ClientDetector;
+
+import java.util.List;
+
+@Primary
+@Component
+@Profile("prod")
+@RequiredArgsConstructor
+public class RealClientDetector implements ClientDetector {
+
+    private final NetworkProperties networkProperties;
+    private final ShellExecutor shellExecutor;
+
+    @Override
+    public List<String> detectIpAddresses() {
+        return shellExecutor.execute("nmap -sn -n %s -oG - | awk '/Host/{print $2}'".formatted(
+                networkProperties.getAddress()
+        ));
+    }
+}

vpn-router-core/src/main/java/vpnrouter/core/infrastructure/shell/ShellExecutor.java

@@ -0,0 +1,34 @@
+package vpnrouter.core.infrastructure.shell;
+
+import lombok.SneakyThrows;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+import vpnrouter.core.exception.UserException;
+
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+@Slf4j
+@Component
+public class ShellExecutor {
+
+    @SneakyThrows
+    public List<String> execute(String command) {
+        var process = new ProcessBuilder("sh", "-c", command).start();
+        var completed = process.waitFor(1, TimeUnit.MINUTES);
+        if (!completed) {
+            log.warn("[{}] -> [TIME OUT]", command);
+            throw new UserException("Shell command execution timed out");
+        }
+        var success = process.exitValue() == 0;
+        try (var reader = process.inputReader()) {
+            var output = reader.lines().toList();
+            if (success) {
+                log.info("[{}] -> [SUCCESS]\n{}", command, String.join("\n", output));
+            } else {
+                log.warn("[{}] -> [FAILURE]\n{}", command, String.join("\n", output));
+            }
+            return output;
+        }
+    }
+}