如何使用setsockopt(SO_REUSEADDR)? [英] How do I use setsockopt(SO_REUSEADDR)?

问题描述

我在树莓派上运行我自己的 http 服务器.问题是当我停止程序并重新启动它时，端口不再可用.有时我在收到大量请求时会遇到同样的问题.
我想使用 SO_REUSEADDR，这样即使发生错误，我也可以继续使用该端口，但没有成功设置它.下面是我的代码.
我得到的错误是绑定错误:地址已在使用中".

I am running my own http server on a raspberry pi. The problem is when I stop the program and restart it, the port is no longer available. Sometimes I get the same issue when receiving lots of requests.
I want to use SO_REUSEADDR so that I can keep using the port even when the error occurs but have had no luck getting it set up. Below is my code.
The error I get is "ERROR on binding:Address already in use".

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>

void error(const char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
    printf("Starting Listener
");
     int sockfd, newsockfd, portno;
     socklen_t clilen;
     char buffer[256];
     struct sockaddr_in serv_addr, cli_addr;
     int n;
     if (argc < 2) {
         fprintf(stderr,"ERROR, no port provided
");
         exit(1);
     }
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     if (sockfd < 0) 
        error("ERROR opening socket");
     bzero((char *) &serv_addr, sizeof(serv_addr));
     portno = atoi(argv[1]);
     serv_addr.sin_family = AF_INET;
     serv_addr.sin_addr.s_addr = INADDR_ANY;
     serv_addr.sin_port = htons(portno);
     if (bind(sockfd, (struct sockaddr *) &serv_addr,
              sizeof(serv_addr)) < 0) 
              error("ERROR on binding");

     printf("about to listen
");
     listen(sockfd,5);
     printf("finished listening
");
     clilen = sizeof(cli_addr);
     printf("About to accept
");

     int i;
     for(i=0; i<100; i++){
         newsockfd = accept(sockfd, 
                 (struct sockaddr *) &cli_addr, 
                 &clilen);

         if (newsockfd < 0) 
             error("ERROR on accept");
         bzero(buffer,256);
         n = read(newsockfd,buffer,255);
         if (n < 0) error("ERROR reading from socket");
         printf("Here is the message: %s
",buffer);
         n = write(newsockfd,"I got your message",18);
         if (n < 0) error("ERROR writing to socket");
         close(newsockfd);
     }
     close(sockfd);
     return 0; 
}

推荐答案

之后:

sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) 
    error("ERROR opening socket");

您可以添加(使用标准的C99复合文字支持):>

You can add (with standard C99 compound literal support) :

if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &(int){1}, sizeof(int)) < 0)
    error("setsockopt(SO_REUSEADDR) failed");

或者:

int enable = 1;
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)) < 0)
    error("setsockopt(SO_REUSEADDR) failed");

这篇关于如何使用setsockopt(SO_REUSEADDR)?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！