TCP 本地通信 accept返回值为0

[Milk_1997]

client.c
[code=c
]/*
* client.c
* 1.0
* fsy
*
*/


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <arpa/inet.h>



#define port 3333

char ipaddr[15];
int sockfd;
struct sockaddr_in servaddr;




static int links()
{
if ((sockfd=socket(AF_INET,SOCK_STREAM,0))== -1)
{
perror("SOCKET");
exit(0);
}

memset(&servaddr,0,sizeof(servaddr));

servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr(ipaddr);
servaddr.sin_port = htons(port);

if ((connect(sockfd,(struct sockaddr*)(&servaddr),sizeof(servaddr))) == -1)
{
perror("CONNECT");
exit(0);
}

return 1;
}

static void upload_file(char * file_name)
{
int fd;
char cmd = 'U';
int size = strlen(file_name);
char buf[1024];
int count;

struct stat file_stat;


if ((fd = open(file_name,O_RDONLY))==-1)
{
perror("OPEN");
printf("This file not found!\n Please input file name again!\n ");
return ; /* this need debug */
}
printf("%d",fd);
/* this need send upload command */
write(sockfd,&cmd,1);

/* this need send file name */
write(sockfd,(void *)(&size),4);
write(sockfd,(void *)(file_name),size);

/* this is send file size */
if((stat(file_name,&file_stat)) == -1)
{
printf("not");
return ; /* this need debug */
}

write(sockfd,(void *)(file_stat.st_size),4);

/*this need send file comment */
while ((count = read(fd,(void *)(buf),1024))>0)
{ printf("ok!");
write(sockfd,&buf,count);
}

close(fd);

}

static void download_file(char *file_name)
{
int fd;
char cmd = 'D';
int size = strlen(file_name);
char buf[1024];
int file_size=0;
int tmp_size=0;
int count=0;


/* this need send upload command */
write(sockfd,(void *)&cmd,1);

/* this need send file name */
write(sockfd,(void *)(&size),4);
write(sockfd,(void *)(file_name),size);

/* this need creat a file to save the download file */
if ((fd = open(file_name,O_RDONLY|O_CREAT,0777))==-1)
{
perror("OPEN");
printf("This file not found!\n Please input file name again!\n ");
return ; /* this need debug */
}

/* this is resave file size */

read(sockfd,&file_size,4);

/*this need save file comment */
while ((count = read(sockfd,(void *)(buf),1024))>0)
{
write(fd,&buf,count);
tmp_size +=count;
printf("%d",tmp_size);
printf("%d",file_size);
if (tmp_size==file_size)
{
break;
printf("%d",tmp_size);
}
}

close(fd);
}

static void quit()
{
char cmd = 'Q';

write(sockfd,(void *)&cmd,1);

system("clear");

exit(0);
}


static void menu()
{
char command;
int c;
char file_u[30];
char file_d[30];
char tmp;


for(;;)
{
printf("\n----------------------------------1.Upload Files ----------------------------------\n");
printf("\n----------------------------------2.Download File----------------------------------\n");
printf("\n----------------------------------3.Quit systerm ----------------------------------\n");

printf("Please input the Client command:\n");

command = getchar();

switch(command)
{
case '1':
{
printf("Please input the file name of u will upload:\n");

while((c = getchar())!= '\n'&& c != EOF ); /* 没有理解之前以为这里是多与的现在理解了知道这个地方是为了 吸 收输入的command之后输入的换行符的 */

fgets(file_u,30,stdin);
file_u[strlen(file_u)-1] = '\0';

upload_file(file_u);
}
break;

case '2' :
{
printf("Please input the file name of u will download:\n");

while((c = getchar())!= '\n'&& c != EOF ); /* 没有理解之前以为这里是多与的现在理解了知道这个地方是为了 吸收输入的command之后输入的换行符的 */

fgets(file_d,30,stdin); /* if use one name what happen! */
file_u[strlen(file_d)-1] = '\0';

download_file(file_d);

}
break;

case '3' :
quit();
break;

default :
printf("Please input right command!\n");
break;
}

}
}

int main(int argc,char *argv[])
{
if(argc!=2)
{
printf("format error: you must enter ipaddr like this: 192.168.1.101!\n");
exit(0);
}

strcpy(ipaddr,argv[1]);

links();

menu();

close(sockfd);

return 0;
}
[/code]

server.c

/*
 *		server.c
 *		1.0
 *		fsy
 *				
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>



#define port 3333

int sockfd;
int new_sockfd;
int file_name_size;
char file_name[100];
int fd;
int file_size;
int tmp_size;
char buf[1024];
struct stat file_stat;
int count;



struct sockaddr_in servaddr,clieaddr;

socklen_t sin_size;

static void handle(char cmd)
{
	switch (cmd)
	{
	case 'U' :
	{
		read(new_sockfd,&file_name_size,4);
		read(new_sockfd,(void *)&file_name,file_name_size);
			file_name[file_name_size]='\0';
			
		if ((fd  =(open(file_name,O_RDWR|O_CREAT,0777)))==-1)
			perror("open error:\n");
		
		read(new_sockfd,&file_size,4);
		

		/*this need save file comment  */
		while ((count = read(new_sockfd,(void *)(buf),1024))>0)
		{
			write(fd,&buf,count);
			tmp_size +=count;
			if (tmp_size==file_size)
				break;
		}
		
		close(fd);
	}
	break;
	
	case 'D':
	{
		
		read(new_sockfd,&file_name_size,4);
		read(new_sockfd,(void *)&file_name,file_name_size);
			file_name[file_name_size-1]='\0';
			
		if ((fd = open(file_name,O_RDONLY))==-1)
			{
				perror("OPEN");
				printf("This file  not found!\n Please input file name again!\n ");
				return ;  /* this need debug */
			}
			
			/* this is send file size  */
			if((stat(file_name,&file_stat)) == -1)
				return ; /* this need debug */
			
			write(new_sockfd,(void *)(file_stat.st_size),sizeof(file_stat.st_size));

			/*this need send file comment  */
			while ((count = read(fd,(void *)(buf),1024))>0)
			{
				write(new_sockfd,&buf,count);
			}
			
			close(fd);
	}
	break;
	}
}




int main (void)
{

	char cmd;
	char i;
	
	
	if ((sockfd=socket(AF_INET,SOCK_STREAM,0)) == -1)
	{
		perror("socket");
		exit(-1);
	}
	
	bzero(&servaddr,sizeof(servaddr));
	
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(port);
	
	if(bind(sockfd,(struct sockaddr*)(&servaddr),sizeof(servaddr))== -1)
	{
		perror("bind");
		exit(1);
	}
	
	if (i=(listen(sockfd,5))==-1)
	{
		perror("listen");
		exit(1);
		
	}
	else
		printf("listen is %d!\n",i);

	for(;;)
	{
		sin_size=sizeof(struct sockaddr);
		printf("%d\n",sin_size);
		
		if(new_sockfd=(accept(sockfd,(struct sockaddr*)(&clieaddr),&sin_size))== -1)
		{
			perror("accept");
			exit(1);
		}
		else 
			printf("new_sockfd is %d!\n",new_sockfd);
		
		for(;;)
		{
			read(new_sockfd,&cmd,1);
			printf("%d",new_sockfd);
			if(cmd=='Q')
			{
				close(new_sockfd);
				break;
			}
			else
			{
				handle(cmd);
			}
			close(new_sockfd);
		}
	}
	close(sockfd);
	return 0;
}

]

我在一台电脑上面测试的这两个程序。
客户端发送完命令之后，服务器接受不到命令，一直在accept那里，返回的新sockfd是0.
操作环境是红帽7

[Wenxy1]

1. linux的帮助文档man man. 2. 你的程序不健壮，应该是网络程序的新手。 3. man accpet查看编程手册。 4. 学学gdb调试。

[braveyly]

抓包分析，三次握手，四次分手过程

[Milk_1997]

谢谢已经找到问题