Linux:回射服务器的粘包

/ Linux / 没有评论 / 1712浏览

粘包问题的简单简单解决:定义整个数据包(包头+包体)

粘包问题的产生: 粘包 当然还有别的原因tcp拥塞,等等情况。

解决粘包的代码

客户端:

#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#define ERR_EXIT(m)do{perror(m);exit(EXIT_FAILURE);}while(0)

struct packet
{
	int len;
	char buf[1024];
};

ssize_t readn(int fd, void *buf, size_t count)
{
	size_t nleft = count;//剩余的字节数
	size_t nread;//接收的字节数 
	char * bufp = (char *)buf;
	while(nleft > 0)
	{
		if((nread = read(fd,bufp,nleft)) < 0)
		{
			if(errno == EINTR)//信号中断
				continue;
			return -1;
		}
		else if(nread == 0) //客户端关闭了
		{
			return count - nleft;
		}
		bufp += nread;
		nleft -=nread;
	}
	return count;
}

ssize_t writen(int fd, const void *buf, size_t count)
{
	size_t nleft = count;//剩余的字节数
	size_t nwritten;//接收的字节数 
	char * bufp = (char *)buf;
	while(nleft > 0)
	{
		if((nwritten = write(fd,bufp,nleft)) < 0)
		{
			if(errno == EINTR)//信号中断
				continue;
			return -1;
		}
		else if(nwritten == 0) //客户端关闭了
		{
			continue;
		}
		bufp += nwritten;
		nleft -=nwritten;
	}
	return count;
}

int main(void)
{
	int sock;
	if((sock = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP)) <0)
	{
		ERR_EXIT("socket");
	}
	struct sockaddr_in servaddr;
	memset(&servaddr,0,sizeof(servaddr));
	servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(5188);

    //servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    //inet_aton("127.0.0.1",&servaddr.sin_addr);
	
	if(connect(sock,(struct sockaddr*)&servaddr,sizeof(servaddr)) < 0)
	{
       ERR_EXIT("connect");
	}

	struct packet sendbuf;
	struct packet recvbuf;
	memset(&sendbuf,0,sizeof(sendbuf));
	memset(&recvbuf,0,sizeof(recvbuf));
	int n;
	while(fgets(sendbuf.buf,sizeof(sendbuf.buf),stdin) != NULL)
	{
		n = strlen(sendbuf.buf);
		sendbuf.len = htonl(n);
		
		writen(sock,&sendbuf,4+n);

		//readn(sock,recvbuf,sizeof(recvbuf));
		
		int ret = readn(sock,&recvbuf.len,4);//接收包头
		if(ret == -1)
		{
			ERR_EXIT("read");
		}
		else if(ret < 4)//客户端关闭
		{
			printf("client close\n");
			break;
		}
		n = ntohl(recvbuf.len);
		ret = readn(sock,recvbuf.buf,n) ;//接收包体
		if(ret == -1)
		{
			ERR_EXIT("read");
		}
		else if(ret < n)//客户端关闭
		{
			printf("client close\n");
			break;
		}

		fputs(recvbuf.buf,stdout);
		memset(&sendbuf,0,sizeof(sendbuf));
		memset(&recvbuf,0,sizeof(recvbuf));
		
	}
	close(sock);
    return 0;
}

服务端:

#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#define ERR_EXIT(m)do{perror(m);exit(EXIT_FAILURE);}while(0)

struct packet
{
	int len;
	char buf[1024];
};

ssize_t readn(int fd, void *buf, size_t count)
{
	size_t nleft = count;//剩余的字节数
	size_t nread;//接收的字节数 
	char * bufp = (char *)buf;
	while(nleft > 0)
	{
		if((nread = read(fd,bufp,nleft)) < 0)
		{
			if(errno == EINTR)//信号中断
				continue;
			return -1;
		}
		else if(nread == 0) //客户端关闭了
		{
			return count - nleft;
		}
		bufp += nread;
		nleft -=nread;
	}
	return count;
}

ssize_t writen(int fd, const void *buf, size_t count)
{
	size_t nleft = count;//剩余的字节数
	size_t nwritten;//接收的字节数 
	char * bufp = (char *)buf;
	while(nleft > 0)
	{
		if((nwritten = write(fd,bufp,nleft)) < 0)
		{
			if(errno == EINTR)//信号中断
				continue;
			return -1;
		}
		else if(nwritten == 0) //客户端关闭了
		{
			continue;
		}
		bufp += nwritten;
		nleft -=nwritten;
	}
	return count;
}

//多个客户端可以连接,将accept弄作一个进程,读取发送数据是一个进程
void do_service(int conn)
{
	struct packet recvbuf;
	int n;
	while(1)
	{
        memset(&recvbuf,0,sizeof(recvbuf));
		int ret = readn(conn,&recvbuf.len,4);//接收包头
		if(ret == -1)
		{
			ERR_EXIT("read");
		}
		else if(ret < 4)//客户端关闭
		{
			printf("client close\n");
			break;
		}
		n = ntohl(recvbuf.len);
		ret = readn(conn,recvbuf.buf,n) ;//接收包体
		if(ret == -1)
		{
			ERR_EXIT("read");
		}
		else if(ret < n)//客户端关闭
		{
			printf("client close\n");
			break;
		}
		fputs(recvbuf.buf,stdout);
		writen(conn,&recvbuf,4+n);
	}
}

int main(void)
{
	int listenfd;
	if((listenfd = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP)) <0)
		//listenfd = socket(PF_INET,SOCK_STREAM,0);
	{
		ERR_EXIT("socket");
	}
	struct sockaddr_in servaddr;
	memset(&servaddr,0,sizeof(servaddr));
	servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(5188);
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    //servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    //inet_aton("127.0.0.1",&servaddr.sin_addr);
	
	//开启地址重复利用(在TIME_WAIT未消失的情况下,允许服务器重启)
	int on = 1;
	if(setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on)) < 0)
		ERR_EXIT("setsockopt");

	if(bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr)) < 0)
		ERR_EXIT("bind");
    
    if(listen(listenfd,SOMAXCONN) < 0)
		ERR_EXIT("listen");
	
	struct sockaddr_in peeraddr;
	socklen_t peerlen = sizeof(peeraddr);
	
	int conn;
	pid_t pid;
	while(1)
	{
		if((conn = accept(listenfd,(struct sockaddr*)&peeraddr, &peerlen)) < 0)
			ERR_EXIT("accept");
		printf("ip=%s port=%d\n",inet_ntoa(peeraddr.sin_addr),ntohs(peeraddr.sin_port));
		pid = fork();
		if(pid == -1)
			ERR_EXIT("fork");
		if(pid == 0)
		{
			close(listenfd);
			do_service(conn);
			exit(EXIT_SUCCESS);
		}
		else
		{
			close(conn);
		}
	}

    return 0;
}

这里只是简单demo。