python - 带套接字的 TCP 客户端/服务器、服务器向客户端发送文件、客户端挂起、Python

Question

我想用 Python 中的套接字编写一个简单的 TCP 服务器。服务器应将图像发送到连接的客户端。客户端应该会收到图像。但是，现在，客户端只收到图像的一部分，我什至无法打开它。

服务器是使用 select 的多客户端，但这不是问题所在。我认为问题在于发送图像。

我希望这里的“协议(protocol)”非常简单。

SERVER                   CLIENT
               GET
       <----------------
              IMAGE
       ----------------->
      END OF COMMUNICATION

所以客户端只能向服务器发送“GET”消息，而服务器在得到“GET”字符串后，应该立即将整个图像发送给客户端。至此，通讯结束。

server.py

#!/usr/bin/env python

import random
import socket, select
from time import gmtime, strftime

image = 'image.png'

HOST = '127.0.0.1'
PORT = 6666

connected_clients_sockets = []

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

server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind((HOST, PORT))
server_socket.listen(10)

connected_clients_sockets.append(server_socket)

while True:

    read_sockets, write_sockets, error_sockets = select.select(connected_clients_sockets, [], [])

    for sock in read_sockets:

        if sock == server_socket:

            sockfd, client_address = server_socket.accept()
            connected_clients_sockets.append(sockfd)

        else:
            try:
                data = sock.recv(4096)
                bytes = open(image).read()

                if data:
                    sock.send(bytes)

            except:
                sock.close()
                connected_clients_sockets.remove(sock)
                continue

server_socket.close()

client.py

#!/usr/bin/env python

import socket
import sys

HOST = '127.0.0.1'
PORT = 6666

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_address = (HOST, PORT)
sock.connect(server_address)

try:

    sock.sendall("GET")

    while True:

        myfile = open('imagefromserv.png', 'w')

        while True:
            data = sock.recv(4096)
            if not data:
                break
            myfile.write(data)
        myfile.close()

finally:
    sock.close()

我在最新的 Ubuntu 上使用 Python 2.7。

------------------------------------------ -------------------------------------------------- --------------------------------------编辑----------------------------------------------- -------------------------------------------------- ----------------------------------

根据其中一位用户在评论中给出的建议，我尝试实现一个简单的协议(protocol):

CLIENT                                      SERVER
                      GET\r\n   
       ----------------------------------->
                      OK\r\n
       <----------------------------------- 
                   GET_SIZE\r\n
       ----------------------------------->
                    SIZE 1024\r\n
       <-----------------------------------
                   GET_IMG\r\n
       ----------------------------------->
                  IMG_DATA\r\r
       <-----------------------------------

一切似乎都正常，但是在图像传输之后，我的 CPU 100% 忙，正如 top 所说。还有....

服务器的输出:

--GET--
--GET_SIZE--
--24518--
--GET_IMG--

客户的输出:

--OK--
--SIZE 24518--
--24518--
4096
8192
12288
16384
20480
24523
Image received successfully

表示客户端成功接收到图片。现在好吗？我的意思是，我从服务器获取了图像，但我不知道我是否正确实现了协议(protocol)。也许这里可以改进一些东西？

client.py:

#!/usr/bin/env python

import socket
import sys

HOST = '127.0.0.1'
PORT = 6666

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_address = (HOST, PORT)
sock.connect(server_address)
fname = 'fromserver.png'

try:

    sock.sendall("GET\r\n")
    data = sock.recv(4096)

    if data:
        txt = data.strip()
        print '--%s--' % txt

        if txt == 'OK':

            sock.sendall("GET_SIZE\r\n")
            data = sock.recv(4096)

            if data:
                txt = data.strip()
                print '--%s--' % txt

                if txt.startswith('SIZE'):

                    tmp = txt.split()
                    size = int(tmp[1])

                    print '--%s--' % size

                    sock.sendall("GET_IMG\r\n")

                    myfile = open(fname, 'wb')

                    amount_received = 0
                    while amount_received < size:
                        data = sock.recv(4096)
                        if not data :
                            break
                        amount_received += len(data)
                        print amount_received

                        txt = data.strip('\r\n')

                        if 'EOF' in str(txt) :
                            print 'Image received successfully'
                            myfile.write(data)
                            myfile.close()
                        else :
                            myfile.write(data)
finally:
    sock.close()

server.py:

    #!/usr/bin/env python

import random
import socket, select
from time import gmtime, strftime

image = 'tux.png'

HOST = '127.0.0.1'
PORT = 6666

connected_clients_sockets = []

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

server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind((HOST, PORT))
server_socket.listen(10)

connected_clients_sockets.append(server_socket)

while True:

    read_sockets, write_sockets, error_sockets = select.select(connected_clients_sockets, [], [])

    for sock in read_sockets:

        if sock == server_socket:

            sockfd, client_address = server_socket.accept()
            connected_clients_sockets.append(sockfd)

        else:
            try:
                data = sock.recv(4096)

                if data :

                    txt = data.strip()
                    print '--%s--'%txt

                    if txt == 'GET' :
                        sock.sendall('OK\r\n')

                    elif txt == 'GET_SIZE' :

                        with open ('tux.png','rb') as f1:
                            file_size = len(f1.read())
                            f1.seek(0)

                        print '--%s--'%file_size

                        file_size = '%s' % file_size
                        sock.sendall('SIZE %s\r\n' % file_size)

                    elif txt == 'GET_IMG' :
                        with open(image, 'rb') as fp:
                            image_data = fp.read()

                        msg = '%sEOF\r\r' % image_data
                        sock.sendall(msg)
                        print msg

            except:
                sock.close()
                connected_clients_sockets.remove(sock)
                continue

server_socket.close()

或者我应该这样做:

sock.sendall(image_data)
sock.sendall('EOF\r\n')

代替:

msg = '%sEOF\r\n' % image_data
sock.sendall(msg)

在客户端？

Answer 1

你不小心忘记了只使用 HTTP 和 Twisted。

服务器:

from twisted.web.static import File
from twisted.web.resource import Resource
def resource():
    resource = Resource()
    resource.putChild(b"", File(u"xkcd/sandwich.png"))
    return resource

客户:

from filepath import FilePath
from twisted.internet.task import react
from treq import get, content

def main(reactor):
    d = get(b"http://localhost:8080/")
    d.addCallback(content)
    d.addCallback(FilePath(u"image.png").setContent)
    return d

react(main, [])

服务器演示:

(everything) exarkun@baryon:/tmp/demo$ twist web --class server.resource
2017-02-23T21:32:14-0500 [-] Site starting on 8080
2017-02-23T21:32:14-0500 [twisted.web.server.Site#info] Starting factory <twisted.web.server.Site instance at 0x7fd1ef81a8c0>
2017-02-23T21:32:14-0500 [twisted.application.runner._runner.Runner#info] Starting reactor...
2017-02-23T21:33:01-0500 [twisted.python.log#info] "127.0.0.1" - - [24/Feb/2017:02:33:01 +0000] "GET / HTTP/1.1" 200 21489 "-" "-"
^C
2017-02-23T21:33:05-0500 [-] Received SIGINT, shutting down.
2017-02-23T21:33:05-0500 [-] (TCP Port 8080 Closed)
2017-02-23T21:33:05-0500 [twisted.web.server.Site#info] Stopping factory <twisted.web.server.Site instance at 0x7fd1ef81a8c0>
2017-02-23T21:33:05-0500 [-] Main loop terminated.
(everything) exarkun@baryon:/tmp/demo$ 

客户端演示:

(everything) exarkun@baryon:/tmp/demo$ ls -l image.png
ls: cannot access 'image.png': No such file or directory
(everything) exarkun@baryon:/tmp/demo$ python client.py 
(everything) exarkun@baryon:/tmp/demo$ ls -l image.png 
-rwxr-xr-x 1 exarkun exarkun 21489 Feb 23 21:33 image.png
(everything) exarkun@baryon:/tmp/demo$

如果你想了解更多关于选择循环驱动网络是如何完成的，你可以阅读 the Twisted implementation .