[linux/unix]getservbyport|getservbyname

#include <stdio.h>
#include <unistd.h>
#include <netdb.h>

int main(int argc,char *argv[])
{
  struct servent serv;
  struct servent *serv_info=&serv;

  serv_info=getservbyport(htons(atoi(argv[1])),NULL);/*第二个参数为协议类型，为NULL时自动匹配所有协议*/
  printf("%s\n%d\n",serv_info->s_name,ntohs(serv_info->s_port));
  serv_info=getservbyport(htons(atoi(argv[1])),"tcp");
                printf("%s\n%d\n",serv_info->s_name,ntohs(serv_info->s_port));
  
  return 0;

}