直接从 /dev/log Unix Domain Socket 读取数据

Question

我的项目旨在直接从 Java 中的/dev/log UNIX 域套接字读取日志消息。目前我正在使用junixsocket。下面是从 unix 套接字读取的客户端示例代码。

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

import org.newsclub.net.unix.AFUNIXSocket;
import org.newsclub.net.unix.AFUNIXSocketAddress;
import org.newsclub.net.unix.AFUNIXSocketException;

public class SimpleTestClient {
    public static void main(String[] args) throws IOException {
        final File socketFile = new File("/dev/log");

        AFUNIXSocket sock = AFUNIXSocket.newInstance();
        try {
            sock.connect(new AFUNIXSocketAddress(socketFile));
        } catch (AFUNIXSocketException e) {
            System.out.println("Cannot connect to server. Have you started it?\n");
            System.out.flush();
            throw e;
        }
        System.out.println("Connected");

        InputStream is = sock.getInputStream();

        byte[] buf = new byte[8192];

        int read = is.read(buf);
        System.out.println("Server says: " + new String(buf, 0, read));

        is.close();

        sock.close();

        System.out.println("End of communication.");
    }
}

上述代码无法连接到/dev/log。它抛出一个异常：

Cannot connect to server. Have you started it? Exception in thread "main" org.newsclub.net.unix.AFUNIXSocketException: Protocol wrong type for socket (socket: /dev/log) at org.newsclub.net.unix.NativeUnixSocket.connect(Native Method) at org.newsclub.net.unix.AFUNIXSocketImpl.connect(AFUNIXSocketImpl.java:125) at org.newsclub.net.unix.AFUNIXSocket.connect(AFUNIXSocket.java:97) at org.newsclub.net.unix.AFUNIXSocket.connect(AFUNIXSocket.java:87) at SimpleTestClient.main(SimpleTestClient.java:40)

我无法弄清楚如何解决这个问题。任何帮助都将不胜感激。

Answer 1

由于您无法连接到日志跟踪中提到的现有服务器套接字，那么您还没有绑定一个提到的文件，因此请尝试创建一个 AF_UNIX 服务器套接字然后连接到它。

它可以在一个单独的类中完成：

public class DevLogServer {

  public static void main(String[] args) throws IOException {

    final File socketFile = new File("/dev/log");
    AFUNIXServerSocket server = AFUNIXServerSocket.newInstance();
    try {
      server.bind(new AFUNIXSocketAddress(socketFile));
    } catch (Exception e) {
      throw e;
    }

  }

}

根据@Ankit 评论编辑：

您可能还需要确保 syslod 守护程序已通过在终端窗口中运行以下命令停止：

sudo service syslog stop

您可能还需要对 /dev 目录授予大写权限。