#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <strings.h>
#define MAXSIZE 4096
#define SERV_PORT 8000
int main(void)
{
int listenFd, connectFd;
struct sockaddr_in servaddr, cliaddr;
socklen_t cliaddr_len;
char buf[MAXSIZE];
char str[INET_ADDRSTRLEN];
ssize_t numRead;
int ret;
listenFd = socket(AF_INET, SOCK_STREAM, 0);
if (-1 == listenFd)
{
perror("socket");
exit(EXIT_FAILURE);
}
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);
int opt = 1;
setsockopt(listenFd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
ret = bind(listenFd, (struct sockaddr *)&servaddr, sizeof(servaddr));
if (-1 == ret)
{
perror("bind");
exit(EXIT_FAILURE);
}
ret = listen(listenFd, 5);
if (-1 == ret)
{
perror("listen");
}
cliaddr_len = sizeof(cliaddr);
connectFd = accept(listenFd, (struct sockaddr *) &cliaddr, &cliaddr_len);
if (-1 == connectFd)
{
perror("accept");
exit(EXIT_FAILURE);
}
printf("receive from %s at PROT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str, INET_ADDRSTRLEN),
ntohs(cliaddr.sin_port));
while (1)
{
numRead = recv(connectFd, buf, MAXSIZE, 0);
if (-1 == numRead)
{
perror("recv");
exit(EXIT_FAILURE);
}
printf("receive: %s\n", buf);
memset(buf, 0, MAXSIZE);
}
return 0;
}
最近在学习Linux 网络，很多不理解。以上时我写一个程序，使用命令netstat -apn | grep 8000查看连接状态，想感受什么叫做TCP是面向连接？
有个问题想请教网友，我写的这个程序只能连接一次，为什么开启第二个客户端开始连接的时候，状态栏会显示ESTABLISHED？
开启第一个客户端时，服务器运行到while(1){}语句内的 numRead = recv(connectFd, buf, MAXSIZE, 0);，一直阻塞在这里；当开启第二个客户端时，应该没有连接上呀？
初学者，求各位大牛帮我分析解释下！最好能够将connect(); accept() 和 TCP层 以及SYN, ACK, 结合起来帮我分析下，十分感激
