Linux 使用sigaction和pthreads进行嗅探

我无法理解一些代码。我不熟悉信号处理pthreads。该代码用于获取ARP缓存等。提供的代码用于打开连接

这是主代码

这是允许连接的代码

这是sigint_handler

问题

我无法具体理解这些台词。action.sa_处理程序如何与sigint_处理程序等同

这两个命令的用途是什么

arp-d%s&&arptables-P输入接受&&arptables--flush&&ip-s邻居刷新所有和回显完成

arptables-P输入接受和&arptables-flush和&ip-s邻居flush all

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阅读相关手册页。读一读这本书。它告诉您，

sa_handler

是一个函数指针。所以给它分配一个函数地址是非常有意义的。对于2，请阅读和手册页。

 pthread_t tid;
  pthread_create(&tid, NULL, &allowAllConnections, NULL);
  struct sigaction action;
    memset(&action, 0, sizeof(action));
    action.sa_handler = &sigint_handler;
    sigaction(SIGINT, &action, &old_action);

void *allowAllConnections(void *arg)
{
  FILE *fp;
  char path[1035];
  int exists = 0;
    while(1)
    {
        sleep(300);
        fp = popen("arptables -P INPUT ACCEPT && arptables --flush && ip -s neighbour flush all", "r");
        if (fp == NULL) {
          printf("Failed to run command\n" );
          exit(1);
        }
        printf("ARP Refresh: Allowing all connections!\n");
    }
    return 0;
}

void sigint_handler(int sig_no){
  FILE *fp;
  char path[1035];
  int exists = 0;
  char j[1024] = "";
  snprintf(j, sizeof(j), "arp -d %s && arptables -P INPUT ACCEPT && arptables --flush && ip -s neighbour flush all && echo done", gateway_ip);

  fp = popen(j, "r");
  if (fp == NULL) {
    printf("Failed to run command\n" );
    exit(1);
  }

  while (fgets(path, sizeof(path)-1, fp) != NULL) {
    printf("%s", path);
  }

  printf("Successfully exited. Flushed ARP table and enabled all ARP connections!\n");
  exit(0);
}

 pthread_create(&tid, NULL, &allowAllConnections, NULL)
memset(&action, 0, sizeof(action));
    action.sa_handler = &sigint_handler;
    sigaction(SIGINT, &action, &old_action);