我是套接字编程的新手,我试图理解htons()
的操作。我已经阅读了互联网上的一些教程,例如this和this。但我无法理解htons()
究竟做了什么。我尝试下面的代码:套接字编程中的htons()函数
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
int main(int argc, char *argv[])
{
int sockfd, newsockfd, portno, clilen;
char buffer[256];
struct sockaddr_in serv_addr, cli_addr;
int n;
/* First call to socket() function */
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
{
perror("ERROR opening socket");
exit(1);
}
/* Initialize socket structure */
bzero((char *) &serv_addr, sizeof(serv_addr));
portno = 5001;
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
/* Now bind the host address using bind() call.*/
if (bind(sockfd, (struct sockaddr *) &serv_addr,
sizeof(serv_addr)) < 0)
{
perror("ERROR on binding");
exit(1);
}
/* Now start listening for the clients, here process will
* go in sleep mode and will wait for the incoming connection
*/
listen(sockfd,5);
clilen = sizeof(cli_addr);
/* Accept actual connection from the client */
newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr,
&clilen);
if (newsockfd < 0)
{
perror("ERROR on accept");
exit(1);
}
/* If connection is established then start communicating */
bzero(buffer,256);
n = read(newsockfd,buffer,255);
if (n < 0)
{
perror("ERROR reading from socket");
exit(1);
}
printf("Here is the message: %s\n",buffer);
/* Write a response to the client */
n = write(newsockfd,"I got your message",18);
if (n < 0)
{
perror("ERROR writing to socket");
exit(1);
}
return 0;
}
的sin_port
的值显示为35091
在调试时,我不知道如何改变portno
从5001
到35091
。有人可以解释价值变化的原因吗?
你对什么是htons()有什么了解?你读过这个:http://en.wikipedia.org/wiki/Endianness。 –
根据Linux手册'htons()'函数将无符号短整数主机从主机字节顺序转换为网络字节顺序。 – Shushant
我知道大Endianne和小Endianne,但我不知道htons()正确的操作! – User123422