myftp_state_machine.c

Linux下的ftp服务器

#include "myftp_state_machine.h"
#include "myftp_cmd_string.h"
#include "public.h"

CMD_HANDLE_STATE cmd_state_list[33]={	
	{"USER", myftp_cmd_handle_user},
	{"PASS", myftp_cmd_handle_pass},
	{"CWD",  myftp_cmd_handle_cwd},
	{"XCWD", myftp_cmd_handle_xcwd},
	{"CDUP", myftp_cmd_handle_cdup},
	{"QUIT", myftp_cmd_handle_quit},
	{"REIN", myftp_cmd_handle_rein},
	{"PORT", myftp_cmd_handle_port},
	{"PASV", myftp_cmd_handle_pasv},
	{"TYPE", myftp_cmd_handle_type},
	{"MODE", myftp_cmd_handle_mode},
	{"RETR", myftp_cmd_handle_retr},
	{"STOR", myftp_cmd_handle_stor},
	{"APPE", myftp_cmd_handle_appe},
	{"REST", myftp_cmd_handle_rest},
	{"RNFR", myftp_cmd_handle_rnfr},
	{"RNTO", myftp_cmd_handle_rnto},
	{"ABOR", myftp_cmd_handle_abor},
	{"DELE", myftp_cmd_handle_dele},
	{"RMD",  myftp_cmd_handle_rmd},
	{"XRMD", myftp_cmd_handle_xrmd},
	{"PWD",  myftp_cmd_handle_pwd},
	{"XPWD", myftp_cmd_handle_xpwd},
	{"MKD",  myftp_cmd_handle_mkd},
	{"XMKD", myftp_cmd_handle_xmkd},
	{"LIST", myftp_cmd_handle_list},
	{"NLST", myftp_cmd_handle_nlst},
	{"SYST", myftp_cmd_handle_syst},
	{"STAT", myftp_cmd_handle_stat},
	{"SIZE", myftp_cmd_handle_size},
	{"HELP", myftp_cmd_handle_help},
	{"NOOP", myftp_cmd_handle_noop},
	{NULL,NULL}
};

/*===============================================================================
function：标记文件类型及权限函数，形如：drwxrwxrwx
===============================================================================*/
void getprio(struct stat *ptr,char *pow)
{
	mode_t modes;
	modes = ptr->st_mode;
	if(S_ISDIR(modes))
		pow[0] = 'd';
	else if(S_ISREG(modes))
		pow[0] = '-';
	else if(S_ISLNK(modes))
		pow[0] = 'l';
	else if(S_ISBLK(modes))
		pow[0] = 'b';
	else if(S_ISCHR(modes))
		pow[0] = 'c';
	else if(S_ISFIFO(modes))
		pow[0] = 'p';
	else if(S_ISSOCK(modes))
		pow[0] = 's';
	else 
		pow[0] = ' ';
	if(modes & S_IRUSR)
		pow[1] = 'r';
	else
		pow[1] = '-';
	if(modes & S_IWUSR)
		pow[2] = 'w';
	else
		pow[2] = '-';
	if(modes & S_IXUSR)
		pow[3] = 'x';
	else
		pow[3] = '-';
	if(modes & S_IRGRP)
		pow[4] = 'r';
	else
		pow[4] = '-';
	if(modes & S_IWGRP)
		pow[5] = 'w';
	else
		pow[5] = '-';
	if(modes & S_IXGRP)
		pow[6] = 'x';
	else
		pow[6] = '-';
	if(modes & S_IROTH)
		pow[7] = 'r';
	else
		pow[7] = '-';
	if(modes & S_IWOTH)
		pow[8] = 'w';
	else
		pow[8] = '-';
	if(modes & S_IXOTH)
		pow[9] = 'x';
	else
		pow[9] = '-';
	pow[10]=0;
}

/*===============================================================================
function：port模式时，将端口字符串转换为数字
注：形如192，168，52，203，14，250将14和250转化为数字并依次存入num数组中
===============================================================================*/
void myftp_str_to_num(int num[], char* p_str)
{
	int len=strlen(p_str);

	int i=1;
	for (;i>=0;i--,len--)
	{
		while(isdigit(*(p_str+len-1)))
		{
			len--;
		}
		num[i]=atoi(p_str+len);
		*(p_str+len-1)='\0';
	}
}

/*===============================================================================
function：将形如192，168，203，203的字符串转换为192.168.203.203类型的字符串
===============================================================================*/
void myftp_ip_to_dot_str(char* p_str)
{
	int i=0;
	while (*(p_str+i))
	{
		if (*(p_str+i) == ',')
		{
			*(p_str+i) = '.';
		}
		i++;
	}
}

/*===============================================================================
function：将主动模式时，得到的客户的形如192，168，203，203，14，156的字符串
		转换为IP地址及端口
注：端口计算公式 14*256+156
===============================================================================*/
void myftp_arg_to_addr(pMYFTP_SESSION p_thesession)
{
	int num[2];

	myftp_str_to_num(num, p_thesession->p_cmd_line->arg);

	int tmp=(num[0]<<=8)+num[1];

	myftp_ip_to_dot_str(p_thesession->p_cmd_line->arg);//inet_addr函数只认识点进十进制的ip字符串。所以这里还得以逗号隔开的ip串转换一下。

	strcpy(p_thesession->remote_data_ip_str, p_thesession->p_cmd_line->arg);

	p_thesession->remote_data_port=tmp;
	
	p_thesession->data_sockaddr.un.u_sockaddr_in.sin_family=AF_INET;

	p_thesession->data_sockaddr.un.u_sockaddr_in.sin_port=htons(tmp);

	p_thesession->data_sockaddr.un.u_sockaddr_in.sin_addr.s_addr=inet_addr(p_thesession->p_cmd_line->arg);

}

/*===============================================================================
function：创建port模式时的数据连接套接字
===============================================================================*/
void myftp_make_port_data_socket(pMYFTP_SESSION p_thesession)
{
	int tmp_data_sock=socket(AF_INET,SOCK_STREAM,0);

	if (-1 == tmp_data_sock)
	{
		die("myftp_make_port_data_socket error.\n");
	}
	p_thesession->port_data_fd=tmp_data_sock;//主动模式数据连接的套节字。
}

/*===============================================================================
function：保存客户密码
===============================================================================*/
void myftp_pwdstr_cpy(pMYFTP_SESSION p_thesession)
{
	strcpy(p_thesession->passwd_str,p_thesession->p_cmd_line->arg);
}

/*===============================================================================
function：用户密码字符串（都为加密后的字符串）验证
===============================================================================*/
int myftp_qualify(char* dst_pwd, char* src_pwd)
{
	return	!strcmp(dst_pwd,src_pwd);
}

/*===============================================================================
function：保存客户名
===============================================================================*/
void myftp_usrstr_cpy(pMYFTP_SESSION p_thesession)
{
	strcpy(p_thesession->user_str,p_thesession->p_cmd_line->arg);
}

/*===============================================================================
function：MD5加密用户密码
===============================================================================*/
char* myftp_mycrypt(const char *passwd,const char *mysalt)
{
	char *spwd=(char*)crypt(passwd,mysalt);//mysalt为密码暗纹的前12位
	return spwd;
}


/*========================================================================
function:FTP 命令分析器函数入口
========================================================================*/
int myftp_state_machine_entry(pMYFTP_SESSION p_thesession)
{	
	int i=0,quit=-1;
	while(cmd_state_list[i].cmd)
	{
		if (strcasecmp(p_thesession->p_cmd_line->cmd,cmd_state_list[i].cmd)==0)
		{
			quit = cmd_state_list[i].cmd_handler(p_thesession);
			break;
		}
		else
			i++;
	}
	if (!cmd_state_list[i].cmd)
	{
		write(p_thesession->cmd_cntl_fd,"500 Unknown command.\r\n",strlen("500 Unknown command.\r\n"));
	}
	return quit;
}

/*===============================================================================
function：USER命令处理函数
===============================================================================*/
int myftp_cmd_handle_user(pMYFTP_SESSION p_thesession)
{
	if(*p_thesession->p_cmd_line->arg=='\n')//user name 不允许为空值
	{
		write(p_thesession->cmd_cntl_fd,"530 Bad command sequence.\r\n",strlen("530 Bad command sequence.\r\n"));
		return -1;
	}
	if(strcmp(p_thesession->p_cmd_line->arg,"anonymous")==0)//如果是匿名用户登录
	{
		if (!myftp_conf.is_allowed_anoymous)//且不允许匿名登录
		{
			write(p_thesession->cmd_cntl_fd, "550 anonymous is not allowed.\r\n", strlen("550 anonymous is not allowed.\r\n"));
			return -1;
		}
	}
	if (strcmp(p_thesession->p_cmd_line->arg,"root")==0)//如果是root用户登录
	{
		if (!myftp_conf.is_allowed_root)//且不允许root登录
		{
			write(p_thesession->cmd_cntl_fd, "550 root is not allowed.\r\n", strlen("550 root is not allowed.\r\n"));
			return -1;
		}
	}
	myftp_usrstr_cpy(p_thesession);//将用户名存放起来
	write(p_thesession->cmd_cntl_fd,"331 Please specify the password.\r\n",strlen("331 Please specify the password.\r\n"));
	return -1;	
}

/*===============================================================================
function：PASS命令处理函数
===============================================================================*/
int myftp_cmd_handle_pass(pMYFTP_SESSION p_thesession)
{
	struct spwd* myspwd=0;
	char mysalt[13]={0};
	char *_spwd=0;
	
	if (seteuid(0) == -1)//如果没有这句，则客户端在手动输入pass命令后，将导致语句：myspwd=getspnam(p_thesession->user_str);\
		不能被执行。因为，此时运行此程序的用户的有效ID在之前已经被切换为非root用户了。
	{
		die("seteuid(0) error\n");
	}
	if (strcmp(p_thesession->user_str,"anonymous")==0)//如果是匿名登录
	{
		strcpy(p_thesession->user_str, "ftp");//用户就为ftp
		p_thesession->is_anonymous=TRUE;
		goto ANONYMOUS;
	}
	if (!(myspwd=getspnam(p_thesession->user_str)))//根据用户名查询,on failure, 0 return.
	{
		goto FAILED_TO_LOGIN;
	}
	
	myspwd=getspnam(p_thesession->user_str);
	strncpy(mysalt,myspwd->sp_pwdp,12);//截取MD5密文的前12位，作为crypt函数的salt参数。
	_spwd=myftp_mycrypt(p_thesession->p_cmd_line->arg,mysalt);//加密用户输入的密码

	if(myftp_qualify(_spwd,myspwd->sp_pwdp))//验证用户密码是否正确
	{
ANONYMOUS:
		myftp_pwdstr_cpy(p_thesession);//将密码存放起
		p_thesession->cur_usr_pwd=getpwnam(p_thesession->user_str);//登录成功后，将当前目录置为家目录,并且改变工作目录为用户家目录。
		setegid(p_thesession->cur_usr_pwd->pw_gid);//设置有效组
		seteuid(p_thesession->cur_usr_pwd->pw_uid);
		chdir(p_thesession->cur_usr_pwd->pw_dir);
		strcpy(p_thesession->cur_dir,p_thesession->cur_usr_pwd->pw_dir);
		write(p_thesession->cmd_cntl_fd,"230 Login successful. Have fun.\r\n",strlen("230 Login successful. Have fun.\r\n"));
	}
	else
	{
FAILED_TO_LOGIN:
		bzero(p_thesession->user_str,USER_LEN);
		write(p_thesession->cmd_cntl_fd,"530 Login incorrect.\r\n",strlen("530 Login incorrect.\r\n"));	
	}
	return -1;
}

/*===============================================================================
function：CWD改变目录命令处理函数
注：如果是匿名登录，只允许其在目录/var/ftp/下操作。只需将所有的包含/var/ftp/字符串的目录
	中的该字符串替换为/，客户端则会自动处理。也就是再不能切换到其它目录下了
===============================================================================*/
int myftp_cmd_handle_cwd(pMYFTP_SESSION p_thesession)
{
	if (*p_thesession->user_str=='\0'||*p_thesession->passwd_str==0)
	{
		write(p_thesession->cmd_cntl_fd,"530 Not logged in.\r\n", strlen("530 Not logged in.\r\n"));
		return -1;
	}
	char tmp_wd[MAX_PATH];
	if (p_thesession->is_anonymous)//如果是匿名登录
	{
		sprintf(tmp_wd,"/var/ftp/%s/",p_thesession->p_cmd_line->arg);
		if (!chdir(tmp_wd))
		{
			strcpy(p_thesession->cur_dir,tmp_wd);
			write(p_thesession->cmd_cntl_fd, "250 Directory successfully changed.\r\n", strlen("250 Directory successfully changed.\r\n"));
		}
		else
			write(p_thesession->cmd_cntl_fd, "550 Failed to change directory.\r\n", strlen("550 Failed to change directory.\r\n"));
		return -1;
				
	}
	if (!chdir(p_thesession->p_cmd_line->arg))
	{
		sprintf(p_thesession->cur_dir,"%s/",getcwd(tmp_wd, MAX_PATH));
		write(p_thesession->cmd_cntl_fd, "250 Directory successfully changed.\r\n", strlen("250 Directory successfully changed.\r\n"));
	}
	else
		write(p_thesession->cmd_cntl_fd, "550 Failed to change directory.\r\n", strlen("550 Failed to change directory.\r\n"));
	return -1;
		
}

/*===============================================================================
function：XCWD命令，与CWD命令处理相同
===============================================================================*/
int myftp_cmd_handle_xcwd(pMYFTP_SESSION p_thesession)