知識點：UNIX網路程式設計第四章， 第五章，第六章

多程序模型：

 #include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<errno.h>
#include<netinet/in.h>
#define SERV_PORT 3000
#define MAXLINE 1024
void str_echo(int sockfd)
{
	ssize_t n;
	char buf[MAXLINE];
again:
	while( (n= read(sockfd, buf ,MAXLINE)) > 0)
		write(sockfd, buf, n);
	if(n<0 && errno == EINTR)
		goto again;
	else if(n<0)
		printf("stro_echo:read error\n");
}

void main(void)
{
	int lfd, cfd;
	struct sockaddr_in serv_addr, clin_addr;
	socklen_t clin_len;
	char buf[MAXLINE];
	pid_t childpid;
	lfd = socket(AF_INET, SOCK_STREAM, 0);
	serv_addr.sin_family = AF_INET;
	serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	serv_addr.sin_port = htons(SERV_PORT);
	bind(lfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
	listen(lfd, 128);
	for(;;){
	clin_len = sizeof(clin_addr);
	cfd = accept(lfd,(struct sockaddr*) &clin_addr, &clin_len);
	if( (childpid = fork()) == 0){
		close(lfd);
		str_echo(cfd);
		exit(0);
	}
	close(cfd);
	}
}
 

多執行緒模型：編譯時記得加上 -lpthread

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<errno.h>
#include<netinet/in.h>
#include<pthread.h>
#define SERV_PORT 3000
#define MAXLINE 1024
static void *str_echo(void *sockfd)
{
	ssize_t n;
	char buf[MAXLINE];
again:
	while( (n= read((int)(sockfd), buf ,MAXLINE)) > 0)
		write((int)(sockfd), buf, n);
	if(n<0 && errno == EINTR)
		goto again;
	else if(n<0)
		printf("stro_echo:read error\n");
	close((int)sockfd);
}

void main(void)
{
	int lfd, cfd;
	struct sockaddr_in serv_addr, clin_addr;
	socklen_t clin_len;
	char buf[MAXLINE];
	pid_t childpid;
	lfd = socket(AF_INET, SOCK_STREAM, 0);
	serv_addr.sin_family = AF_INET;
	serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	serv_addr.sin_port = htons(SERV_PORT);
	bind(lfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
	listen(lfd, 128);
	for(;;){
	clin_len = sizeof(clin_addr);
	cfd = accept(lfd,(struct sockaddr*) &clin_addr, &clin_len);
	pthread_t tid;
	pthread_create(&tid, NULL, &str_echo,(void *) cfd);
	}
	close(lfd);
}
 

IO複用：

因為select和poll都存在很多缺陷，這裡選用新的epoll函式來實現。

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<sys/epoll.h>
#include<errno.h>
#include<netinet/in.h>
#define SERV_PORT 3000
#define MAXLINE 1024
void str_echo(int sockfd)
{
	ssize_t n;
	char buf[MAXLINE];
again:
	while( (n= read(sockfd, buf ,MAXLINE)) > 0)
		write(sockfd, buf, n);
	if(n<0 && errno == EINTR)
		goto again;
	else if(n<0)
		printf("stro_echo:read error\n");
}
void main(void)
{
	int lfd, cfd, efd;
	struct sockaddr_in serv_addr, clin_addr;
	socklen_t clin_len;
	char buf[MAXLINE];
	int len, n;
	struct epoll_event tep, ep[1024]; 
	lfd = socket(AF_INET, SOCK_STREAM, 0);
	serv_addr.sin_family = AF_INET;
	serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	serv_addr.sin_port = htons(SERV_PORT);
	bind(lfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
	listen(lfd, 128);
	efd = epoll_create(1024);
	tep.events = EPOLLIN;
	tep.data.fd = lfd;
	epoll_ctl(efd, EPOLL_CTL_ADD, lfd, &tep);
	for(;;){
	n = epoll_wait(efd, ep, 1024, -1);
	int  i = 0;
	for( i =0;i<n;i++){
	
	clin_len = sizeof(clin_addr);
	cfd = accept(lfd,(struct sockaddr*) &clin_addr, &clin_len);
	str_echo(cfd);
	close(cfd);
	}
	}
	close(lfd);
}