#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>

#define SOCKET_PATH "/tmp/unix_dgram_demo"

int main() {
  int                sock_fd;
  struct sockaddr_un server_addr, client_addr;
  socklen_t          client_len;
  char               buffer[10240];

  // Create socket
  sock_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
  if (sock_fd == -1) {
    perror("socket");
    exit(EXIT_FAILURE);
  }

  // Remove socket file if it already exists
  unlink(SOCKET_PATH);

  // Configure server address
  memset(&server_addr, 0, sizeof(server_addr));
  server_addr.sun_family = AF_UNIX;
  strncpy(server_addr.sun_path, SOCKET_PATH, sizeof(server_addr.sun_path) - 1);

  // Bind socket to address
  if (bind(sock_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
    perror("bind");
    close(sock_fd);
    exit(EXIT_FAILURE);
  }

  // 设置超时时间为5秒
  struct timeval tv;
  tv.tv_sec  = 1;  // 秒
  tv.tv_usec = 0;  // 微秒

  // 设置SO_RCVTIMEO选项
  if (setsockopt(sock_fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
    perror("setsockopt failed");
    return -1;
  }

  printf("Receiver is waiting for messages on %s...\n", SOCKET_PATH);

  while (1) {
    // Receive message
    client_len        = sizeof(client_addr);
    ssize_t num_bytes = recvfrom(sock_fd, buffer, sizeof(buffer) - 1, 0, (struct sockaddr *)&client_addr, &client_len);
    if (num_bytes == -1) {
      if (errno == EAGAIN || errno == EWOULDBLOCK) {  // 超时错误
        printf("No message received within the timeout period.\n");
        continue;
      }

      perror("!!!recvfrom");
      exit(EXIT_FAILURE);
    } else {
      buffer[num_bytes] = '\0';
      printf("Received message: %d\n", num_bytes);
    }
  }

  // Clean up
  close(sock_fd);
  unlink(SOCKET_PATH);

  return 0;
}