CLIEN端发给SERVER端.发送数据包的格式是：

1.文件名的大小

2.文件名

3.文件数据大小

4.文件数据

common.h：公共信息

#ifndef COMMON_H
#define COMMON_H

#define SERVER_IP "192.168.0.88"
#define SERVER_PORT 60021
#define MAX_CONNETCTION 30
#define DEBUG

#endif /*COMMON_H*/

client端

net_send.h:定义了文件传输的相关结构体

#ifndef NET_SEND_H
#define NET_SEND_H

#define MAX_FILE_NAME 255
#define BUF_SIZE 512

#define FD_NOT_SET 0
#define FD_OK 1

#define FAILED -1
#define SUCCESS 0

typedef struct net_file{
int file_name_size;
unsigned long file_data_size;
int fd;
int fd_stat;
char file_to_send[MAX_FILE_NAME];
char buf[BUF_SIZE];
}netfile_t;

int open_net_file(netfile_t *netfile,char *filename);
int send_net_file(netfile_t *netfile,char *server_ip,short server_port);
void close_net_file(netfile_t *netfile);

#endif /*NET_SEND_H*/

net_send.c:实现文件，关键步骤红色标记

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include "common.h"
#include "net_send.h"

static unsigned long get_file_size(char *filename)
{
struct stat f_stat;

if(stat(filename,&f_stat) < 0)
return 0;

return (unsigned long)f_stat.st_size;
}

int open_net_file(netfile_t *netfile,char *filename)
{
if(netfile == NULL || filename == NULL)
return ;

bzero(netfile,sizeof(netfile_t));

memcpy(netfile->file_to_send,basename(filename),strlen(basename(filename)));
#ifdef DEBUG
printf("netfile->file_to_send = \"%s\".\n",netfile->file_to_send);
#endif
netfile->fd = open(filename,O_RDONLY);

if(netfile->fd < 0)
{
netfile->fd_stat = FD_NOT_SET;
return FAILED;
}

netfile->file_name_size = strlen(netfile->file_to_send);
netfile->file_data_size = get_file_size(filename);
#ifdef DEBUG
printf("filesize = %d.\n",netfile->file_data_size);
#endif
if(netfile->file_data_size == 0)
{
close(netfile->fd);
netfile->fd_stat = FD_NOT_SET;
return FAILED;
}

netfile->fd_stat = FD_OK;
return SUCCESS;
}

/*-----sending data-----*/

static int send_block(int sock_fd,const char *buf,int size)
{
if(send(sock_fd,buf,size,0) < 0)
return FAILED;
return SUCCESS;
}

int send_net_file(netfile_t *netfile,char *server_ip,short server_port)
{
int sock_fd;
struct sockaddr_in server_addr;
int bytes_read;

if(netfile == NULL || server_ip == NULL)
return FAILED;

if(netfile->fd_stat == FD_NOT_SET)
return FAILED;

if((sock_fd = socket(AF_INET,SOCK_STREAM,0)) == -1)
return FAILED;

bzero(&server_addr,sizeof(struct sockaddr_in));