Python using socket to make an ftp client

费了下午写了这么点东西，也是醉了。

1. 内容主要是请求到ftp服务器，然后下载一个文件。没有实现模块化，只是简单的实现了。（这都哭了）
2. 遇到的问题：对于 ftp需要的两个请求没有清楚和对ftp服务器的机制没有弄清楚
3. 在代码中说明

#download a folder's files 

import socket

class ParseUrl():

    """docstring for ParseUrl"""

    def __init__(self, url):

        self.url = url

        self.method = ""

        self.host = ""

        self.port =""

    def get_method(self):

        method_url = self.url

        self.method = method_url.split(":")[0]

        print "Request Method:",self.method

        return self.method

    def get_host(self):

        temp_pos = self.url.find("://")

        temp_url = self.url[temp_pos+3:]

        

        self.host = temp_url[:temp_url.find(":")]

        print "Request Host:",self.host

        return self.host

    def get_port(self):

        tem_url = self.url.split(":")[2]

      

        if tem_url.find("/"):

            tem_url = tem_url[:tem_url.find("/")]

        print "Request Port:",tem_url  

        self.port = tem_url

        return self.port 

    def parse(self):

        temp_methd = self.get_method()

        temp_host = self.get_host()

        temp_port = self.get_port()

        return temp_methd,temp_host,temp_port

def main():

    #ftp url   这一步是解析一个ftp请求 得到host和port

    request_url = "ftp://localhost:2121/"

    parse_url = ParseUrl(request_url)

    method,host,port = parse_url.parse()

    print "method,host,port",method,host,port

    

#get connection to ftp server

    ftp_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)

    ftp_socket.connect((host,int(port)))

    user = "admin "

    password = "admin "

    print ftp_socket.recv(1024)

    ftp_socket.send("USER "+user)

    print ftp_socket.recv(1024)

    ftp_socket.send("PASS "+password)

    print ftp_socket.recv(1024)

    ftp_socket.send("CWD ")

    print ftp_socket.recv(1024)

    ftp_socket.send("TYPE ASCII ")

    print ftp_socket.recv(1024)

    

   

    ftp_socket.send("SIZE my.txt ")

    temp_size = ftp_socket.recv(1024)

    file_size = int(temp_size.split(" ")[1])

    print file_size

#LIST 

    ftp_socket.send("PASV ")

    new_port = ftp_socket.recv(1024)

    print new_port

    before_port = ""

    temp_port =""

    if new_port.startswith("227"):

        temp_port = new_port.split(",")[5]

        before_port = new_port.split(",")[4]

        temp_port = temp_port.replace(") ","")

    #get the server's new port   

    new_request_port = int(before_port)*256+int(temp_port)

    # connect to the server's new port

    ftp_data_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)

    ftp_data_socket.connect((host,new_request_port))

    ftp_socket.send("LIST ")

    

    print ftp_data_socket.recv(1024).decode("utf-8")

    

    ftp_socket.recv(1024)

#RETR

    ftp_socket.send("PASV ")

    new_port = ftp_socket.recv(1024)

    print new_port

    before_port = ""

    temp_port =""

    if new_port.startswith("227"):

        temp_port = new_port.split(",")[5]

        before_port = new_port.split(",")[4]

        temp_port = temp_port.replace(") ","")

    #get the server's new port   

    new_request_port = int(before_port)*256+int(temp_port)

    # connect to the server's new port

    ftp_data_socket = socket.socket(socket.AF_INET,socket.SOCK_STREAM)

    ftp_data_socket.connect((host,new_request_port))

    ftp_socket.send("RETR my.txt ")

    file_content = ftp_data_socket.recv(file_size)

    

    print file_content

    download_file = open("my.txt","wb")

    download_file.write(file_content)

    download_file.close()

    #print  create_data_connection(ftp_socket,"LIST","",host)

if __name__ == '__main__':

    main()