一、TCP多进程并发

1.地址快速重用

先退出服务端，后退出客户端，则服务端会出现以下错误：

地址仍在使用中

解决方法：

/*地址快速重用*/
    int flag=1,len= sizeof (int);
    if ( setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, len) == -1) {
              perror("setsockopt");
              exit(1);
    }

 2.多进程并发

1）fork函数

#include <stdio.h>
#include <wait.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    pid_t pid = fork();
    if(pid < 0){
        perror("fork");
        exit(0);
    }else if(pid == 0){
        printf("This is child process.\n");
    }else{
        printf("This is father process.\n");
        wait(NULL);
    }
    return 0;
}

2）多个客户端

代码演示

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>

#define BACKLOG 5
void ClinetHandle(int newfd);
int main(int argc, char *argv[])
{
	int fd, newfd;
	struct sockaddr_in addr, clint_addr;
	socklen_t addrlen = sizeof(clint_addr);
	
	pid_t pid;
	
	if(argc < 3){
		fprintf(stderr, "%s<addr><port>\n", argv[0]);
		exit(0);
	}

	/*创建套接字*/
	fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd < 0){
		perror("socket");
		exit(0);
	}
	addr.sin_family = AF_INET;
	addr.sin_port = htons( atoi(argv[2]) );
	if ( inet_aton(argv[1], &addr.sin_addr) == 0) {
		fprintf(stderr, "Invalid address\n");
		exit(EXIT_FAILURE);
	}

	/*地址快速重用*/
	int flag=1,len= sizeof (int); 
	if ( setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, len) == -1) { 
		      perror("setsockopt"); 
			        exit(1); 
	} 
	/*绑定通信结构体*/
	if(bind(fd, (struct sockaddr *)&addr, sizeof(addr) ) == -1){
		perror("bind");
		exit(0);
	}
	/*设置套接字为监听模式*/
	if(listen(fd, BACKLOG) == -1){
		perror("listen");
		exit(0);
	}
	while(1){
		/*接受客户端的连接请求，生成新的用于和客户端通信的套接字*/
		newfd = accept(fd, (struct sockaddr *)&clint_addr, &addrlen);
		if(newfd < 0){
			perror("accept");
			exit(0);
		}
		printf("addr:%s port:%d\n", inet_ntoa(clint_addr.sin_addr), ntohs(clint_addr.sin_port) );
		if( (pid = fork() ) < 0){
			perror("fork");
			exit(0);
		}else if(pid == 0){
			close(fd);
			ClinetHandle(newfd);
			exit(0);
		}
		else
			close(newfd);
	}
	close(fd);
	return 0;
}
void ClinetHandle(int newfd){
	int ret;
	char buf[BUFSIZ] = {};
	while(1){
		//memset(buf, 0, BUFSIZ);
		bzero(buf, BUFSIZ);        //初始化
		ret = read(newfd, buf, BUFSIZ);
		if(ret < 0)
		{
			perror("read");
			exit(0);
		}
		else if(ret == 0)
			break;
		else
			printf("buf = %s\n", buf);
	}
	close(newfd);
}

二、僵尸进程处理

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <signal.h>
#include <sys/wait.h>

#define BACKLOG 5
void SigHandle(int sig){
	if(sig == SIGCHLD){
		printf("client exited\n");
		wait(NULL);
	}
}
void ClinetHandle(int newfd);
int main(int argc, char *argv[])
{
	int fd, newfd;
	struct sockaddr_in addr, clint_addr;
	socklen_t addrlen = sizeof(clint_addr);

#if 0
	struct sigaction act;
	act.sa_handler = SigHandle;
	act.sa_flags = SA_RESTART;
	sigemptyset(&act.sa_mask);
	sigaction(SIGCHLD, &act, NULL);
#else
	signal(SIGCHLD, SigHandle);
#endif

	pid_t pid;
	
	if(argc < 3){
		fprintf(stderr, "%s<addr><port>\n", argv[0]);
		exit(0);
	}

	/*创建套接字*/
	fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd < 0){
		perror("socket");
		exit(0);
	}
	addr.sin_family = AF_INET;
	addr.sin_port = htons( atoi(argv[2]) );
	if ( inet_aton(argv[1], &addr.sin_addr) == 0) {
		fprintf(stderr, "Invalid address\n");
		exit(EXIT_FAILURE);
	}

	/*地址快速重用*/
	int flag=1,len= sizeof (int); 
	if ( setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, len) == -1) { 
		      perror("setsockopt"); 
			        exit(1); 
	} 
	/*绑定通信结构体*/
	if(bind(fd, (struct sockaddr *)&addr, sizeof(addr) ) == -1){
		perror("bind");
		exit(0);
	}
	/*设置套接字为监听模式*/
	if(listen(fd, BACKLOG) == -1){
		perror("listen");
		exit(0);
	}
	while(1){
		/*接受客户端的连接请求，生成新的用于和客户端通信的套接字*/
		newfd = accept(fd, (struct sockaddr *)&clint_addr, &addrlen);
		if(newfd < 0){
			perror("accept");
			exit(0);
		}
		printf("addr:%s port:%d\n", inet_ntoa(clint_addr.sin_addr), ntohs(clint_addr.sin_port) );
		if( (pid = fork() ) < 0){
			perror("fork");
			exit(0);
		}else if(pid == 0){
			close(fd);
			ClinetHandle(newfd);
			exit(0);
		}
		else
			close(newfd);
	}
	close(fd);
	return 0;
}
void ClinetHandle(int newfd){
	int ret;
	char buf[BUFSIZ] = {};
	while(1){
		//memset(buf, 0, BUFSIZ);
		bzero(buf, BUFSIZ);
		ret = read(newfd, buf, BUFSIZ);
		if(ret < 0)
		{
			perror("read");
			exit(0);
		}
		else if(ret == 0)
			break;
		else
			printf("buf = %s\n", buf);
	}
	close(newfd);
}

三、TCP并发多线程

 

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <pthread.h>

#define BACKLOG 5

void *ClinetHandle(void *arg);
int main(int argc, char *argv[])
{
	int fd, newfd;
	struct sockaddr_in addr, clint_addr;
	pthread_t tid;
	socklen_t addrlen = sizeof(clint_addr);
	
	if(argc < 3){
		fprintf(stderr, "%s<addr><port>\n", argv[0]);
		exit(0);
	}

	/*创建套接字*/
	fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd < 0){
		perror("socket");
		exit(0);
	}
	addr.sin_family = AF_INET;
	addr.sin_port = htons( atoi(argv[2]) );
	if ( inet_aton(argv[1], &addr.sin_addr) == 0) {
		fprintf(stderr, "Invalid address\n");
		exit(EXIT_FAILURE);
	}

	/*地址快速重用*/
	int flag=1,len= sizeof (int); 
	if ( setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, len) == -1) { 
		      perror("setsockopt"); 
			        exit(1); 
	} 
	/*绑定通信结构体*/
	if(bind(fd, (struct sockaddr *)&addr, sizeof(addr) ) == -1){
		perror("bind");
		exit(0);
	}
	/*设置套接字为监听模式*/
	if(listen(fd, BACKLOG) == -1){
		perror("listen");
		exit(0);
	}
	while(1){
		/*接受客户端的连接请求，生成新的用于和客户端通信的套接字*/
		newfd = accept(fd, (struct sockaddr *)&clint_addr, &addrlen);
		if(newfd < 0){
			perror("accept");
			exit(0);
		}
		printf("addr:%s port:%d\n", inet_ntoa(clint_addr.sin_addr), ntohs(clint_addr.sin_port) );
		pthread_create(&tid, NULL, ClinetHandle, &newfd);    //创建线程
		pthread_detach(tid);    //设置为分离属性
	}
	close(fd);
	return 0;
}
void *ClinetHandle(void *arg){
	int ret;
	char buf[BUFSIZ] = {};
	int newfd = *(int *)arg;    //传参，强转
	while(1){
		//memset(buf, 0, BUFSIZ);
		bzero(buf, BUFSIZ);
		ret = read(newfd, buf, BUFSIZ);
		if(ret < 0)
		{
			perror("read");
			exit(0);
		}
		else if(ret == 0)
			break;
		else
			printf("buf = %s\n", buf);
	}
	printf("client exited\n");
	close(newfd);
	return NULL;
}

Makefile

CC=gcc
CFLAGS=-Wall
all:client server

server:server.c
    $(CC) $^ -Wall -o $@ -lpthread

clean:
    rm client server