ftp.txt

本程序为在linux下实现FTP传输文件的实现

         APPEND (with create) (APPE)

            This command causes the server-DTP to accept the data
            transferred via the data connection and to store the data in
            a file at the server site.  If the file specified in the
            pathname exists at the server site, then the data shall be
            appended to that file; otherwise the file specified in the
            pathname shall be created at the server site.

         ALLOCATE (ALLO)

            This command may be required by some servers to reserve
            sufficient storage to accommodate the new file to be
            transferred.  The argument shall be a decimal integer
            representing the number of bytes (using the logical byte
            size) of storage to be reserved for the file.  For files
            sent with record or page structure a maximum record or page
            size (in logical bytes) might also be necessary; this is
            indicated by a decimal integer in a second argument field of


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RFC 959                                                     October 1985
File Transfer Protocol


            the command.  This second argument is optional, but when
            present should be separated from the first by the three
            Telnet characters <SP> R <SP>.  This command shall be
            followed by a STORe or APPEnd command.  The ALLO command
            should be treated as a NOOP (no operation) by those servers
            which do not require that the maximum size of the file be
            declared beforehand, and those servers interested in only
            the maximum record or page size should accept a dummy value
            in the first argument and ignore it.

         RESTART (REST)

            The argument field represents the server marker at which
            file transfer is to be restarted.  This command does not
            cause file transfer but skips over the file to the specified
            data checkpoint.  This command shall be immediately followed
            by the appropriate FTP service command which shall cause
            file transfer to resume.

         RENAME FROM (RNFR)

            This command specifies the old pathname of the file which is
            to be renamed.  This command must be immediately followed by
            a "rename to" command specifying the new file pathname.

         RENAME TO (RNTO)

            This command specifies the new pathname of the file
            specified in the immediately preceding "rename from"
            command.  Together the two commands cause a file to be
            renamed.

         ABORT (ABOR)

            This command tells the server to abort the previous FTP
            service command and any associated transfer of data.  The
            abort command may require "special action", as discussed in
            the Section on FTP Commands, to force recognition by the
            server.  No action is to be taken if the previous command
            has been completed (including data transfer).  The control
            connection is not to be closed by the server, but the data
            connection must be closed.

            There are two cases for the server upon receipt of this
            command: (1) the FTP service command was already completed,
            or (2) the FTP service command is still in progress.



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RFC 959                                                     October 1985
File Transfer Protocol


               In the first case, the server closes the data connection
               (if it is open) and responds with a 226 reply, indicating
               that the abort command was successfully processed.

               In the second case, the server aborts the FTP service in
               progress and closes the data connection, returning a 426
               reply to indicate that the service request terminated
               abnormally.  The server then sends a 226 reply,
               indicating that the abort command was successfully
               processed.

         DELETE (DELE)

            This command causes the file specified in the pathname to be
            deleted at the server site.  If an extra level of protection
            is desired (such as the query, "Do you really wish to
            delete?"), it should be provided by the user-FTP process.

         REMOVE DIRECTORY (RMD)

            This command causes the directory specified in the pathname
            to be removed as a directory (if the pathname is absolute)
            or as a subdirectory of the current working directory (if
            the pathname is relative).  See Appendix II.

         MAKE DIRECTORY (MKD)

            This command causes the directory specified in the pathname
            to be created as a directory (if the pathname is absolute)
            or as a subdirectory of the current working directory (if
            the pathname is relative).  See Appendix II.

         PRINT WORKING DIRECTORY (PWD)

            This command causes the name of the current working
            directory to be returned in the reply.  See Appendix II.

         LIST (LIST)

            This command causes a list to be sent from the server to the
            passive DTP.  If the pathname specifies a directory or other
            group of files, the server should transfer a list of files
            in the specified directory.  If the pathname specifies a
            file then the server should send current information on the
            file.  A null argument implies the user's current working or
            default directory.  The data transfer is over the data
            connection in type ASCII or type EBCDIC.  (The user must


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File Transfer Protocol


            ensure that the TYPE is appropriately ASCII or EBCDIC).
            Since the information on a file may vary widely from system
            to system, this information may be hard to use automatically
            in a program, but may be quite useful to a human user.

         NAME LIST (NLST)

            This command causes a directory listing to be sent from
            server to user site.  The pathname should specify a
            directory or other system-specific file group descriptor; a
            null argument implies the current directory.  The server
            will return a stream of names of files and no other
            information.  The data will be transferred in ASCII or
            EBCDIC type over the data connection as valid pathname
            strings separated by <CRLF> or <NL>.  (Again the user must
            ensure that the TYPE is correct.)  This command is intended
            to return information that can be used by a program to
            further process the files automatically.  For example, in
            the implementation of a "multiple get" function.

         SITE PARAMETERS (SITE)

            This command is used by the server to provide services
            specific to his system that are essential to file transfer
            but not sufficiently universal to be included as commands in
            the protocol.  The nature of these services and the
            specification of their syntax can be stated in a reply to
            the HELP SITE command.

         SYSTEM (SYST)

            This command is used to find out the type of operating
            system at the server.  The reply shall have as its first
            word one of the system names listed in the current version
            of the Assigned Numbers document [4].

         STATUS (STAT)

            This command shall cause a status response to be sent over
            the control connection in the form of a reply.  The command
            may be sent during a file transfer (along with the Telnet IP
            and Synch signals--see the Section on FTP Commands) in which
            case the server will respond with the status of the
            operation in progress, or it may be sent between file
            transfers.  In the latter case, the command may have an
            argument field.  If the argument is a pathname, the command
            is analogous to the "list" command except that data shall be


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File Transfer Protocol


            transferred over the control connection.  If a partial
            pathname is given, the server may respond with a list of
            file names or attributes associated with that specification.
            If no argument is given, the server should return general
            status information about the server FTP process.  This
            should include current values of all transfer parameters and
            the status of connections.

         HELP (HELP)

            This command shall cause the server to send helpful
            information regarding its implementation status over the
            control connection to the user.  The command may take an
            argument (e.g., any command name) and return more specific
            information as a response.  The reply is type 211 or 214.
            It is suggested that HELP be allowed before entering a USER
            command. The server may use this reply to specify
            site-dependent parameters, e.g., in response to HELP SITE.

         NOOP (NOOP)

            This command does not affect any parameters or previously
            entered commands. It specifies no action other than that the
            server send an OK reply.


关于FTP的断点续传 
作者: ppnote 发表日期: 2006-10-22 23:38 文章属性: 原创 复制链接  


断点续传的功能实现其实就是把服务器上的文件和本地的文件作一个文件指针的同步，然后通知开始下载或者上传。

FTP的上传和下载是在2个通道分别是命令通道和数据通道中进行。在编程中要注意到这一点。这个当时我就走了弯路，
没注意到，呵呵。

具体的实现是：
1）上传，要用到下面的命令
USER
PASS 
TYPE I
CWD
PASV
SIZE
REST
STOR
首先用SIZE获得服务器上文件的大小，然后发送REST通知服务器定位到某个文件的读写点，在本地的文件也要手动定
位到该文件的读写点，发送STOR开始传送数据。

2）下载，要用到
USER
PASS 
TYPE I
CWD
PASV
SIZE
REST
RETR
首先用api获得本地文件的大小，然后发送REST通知服务器定位到某个文件的读写点，在本地的文件也要手动定位到该
文件的读写点，发送RETR开始接收数据。

具体的命令要查FTP协议：rfc959。
----------------------------------------------------------------------------------------
附录：
命令 描述 

ABOR 中断数据连接程序 
ACCT   account> 系统特权帐号 
ALLO   bytes> 为服务器上的文件存储器分配字节 
APPE   filename> 添加文件到服务器同名文件 
CDUP   dir path> 改变服务器上的父目录 
CWD   dir path> 改变服务器上的工作目录 
DELE   filename> 删除服务器上的指定文件 
HELP   command> 返回指定命令信息 
LIST   name> 如果是文件名列出文件信息，如果是目录则列出文件列表 
MODE   mode> 传输模式（S=流模式，B=块模式，C=压缩模式） 
MKD   directory> 在服务器上建立指定目录 
NLST   directory> 列出指定目录内容 
NOOP 无动作，除了来自服务器上的承认 
PASS   password> 系统登录密码 
PASV   请求服务器等待数据连接 
PORT   address> IP 地址和两字节的端口 ID 
PWD   显示当前工作目录 
QUIT 从 FTP 服务器上退出登录 
REIN 重新初始化登录状态连接 
REST   offset> 由特定偏移量重启文件传递 
RETR   filename> 从服务器上找回（复制）文件 
RMD   directory> 在服务器上删除指定目录 
RNFR   old path> 对旧路径重命名 
RNTO   new path> 对新路径重命名 
SITE   params> 由服务器提供的站点特殊参数 
SMNT   pathname> 挂载指定文件结构 
STAT   directory> 在当前程序或目录上返回信息 
STOR   filename> 储存（复制）文件到服务器上 
STOU   filename> 储存文件到服务器名称上 
STRU   type> 数据结构（F=文件，R=记录，P=页面） 
SYST   返回服务器使用的操作系统 
TYPE   data type> 数据类型（A=ASCII，E=EBCDIC，I=binary） 
USER   username>> 系统登录的用户名 


标准 FTP 信息如下： 

响应代码 解释说明 
110 新文件指示器上的重启标记 
120 服务器准备就绪的时间（分钟数） 
125 打开数据连接，开始传输 
150 打开连接 
200 成功 
202 命令没有执行 
211 系统状态回复 
212 目录状态回复 
213 文件状态回复 
214 帮助信息回复