#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int _valid_ipv4_port(const char *str, int port)
{
  int ret;
  int fd;
  int i;
  volatile int local_errno;
  struct sockaddr_in addr;
  fd = socket(AF_INET,SOCK_STREAM,0); //初始化socket
 
  
  if(fd ==-1) //检查是否正常初始化socket
  {
     return -1;
  }

  errno = 0;
  local_errno = errno;

  ret = inet_pton(AF_INET, str ,&addr.sin_addr);
  printf("the value of ret is:%d\n",ret);
  if(ret > 0)
    {
     fprintf(stderr, "\"%s\" is a vaild IPv4 address\n", str);
     
     addr.sin_family = AF_INET;   //地址结构的协议簇
     addr.sin_port=htons(port);   //地址结构的端口地址，网络字节序
     printf("the value of str:%s\n", str);
     i = (bind(fd, (struct sockaddr*)&addr, sizeof(struct sockaddr)));
     printf("the value of i:%d\n", i);

     if( i < 0)
       {
        printf("port %d has been used. \n", port);
        close(fd);
        return -1;
       }

     printf("port %d is ok. \n", port);
     close(fd);
     return 0;
    }
    
  else if (ret < 0)
    {
     fprintf(stderr, "EAFNOSUPPORT: %s\n", strerror(local_errno));
     return -1;
    }
  else
    {
     fprintf(stderr, "\"%s\" is not a vaild IPv4 address\n", str);
     return -1;
    }
}



int main()
{  
   char a[] ="192.168.209.193";
   char *pIP = a;
   char *pNotIP = "192.168.0.256";
   int port = 56298;  
   int port1 = 3369; 
   _valid_ipv4_port(pIP, port);
   _valid_ipv4_port(pIP, port1);
   _valid_ipv4_port(pNotIP, port1);

   return 0;
}