带有套接字的TCP客户端/服务器,向客户端发送文件的服务器,客户端挂起,Python

Question

我想在Python中使用套接字编写一个简单的TCP服务器.服务器应将映像发送到连接的客户端.客户端应该接收图像.但是,就目前而言,客户端只接收图像的一部分,我甚至无法打开它.

服务器是使用select的多客户端,但这不是问题.我认为问题在于发送图像.

我希望"协议"在这里非常简单.

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

因此客户端只能向服务器发送"GET"消息,服务器在获得"GET"字符串后,应立即将整个映像发送给客户端.就是这样,沟通就结束了.

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 ----------------- -------------------------------------------------- -------------------------------------------------- ---------------

根据评论中的一个用户给出的建议,我试着实现一个简单的协议:

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

一切似乎都有效,但在图像传输后,我的CPU 100%忙碌,top如上所述.并....

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

表示客户端已成功接收图像.现在好吗？我的意思是,我从服务器获得了图像,但我不知道,如果我正确地实现了协议.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()

或许我应该这样做:

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

代替:

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

在客户？

Answer 1

你不小心忘了使用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$

如果您想了解有关如何完成选择循环驱动网络的更多信息,您可以仔细阅读Twisted实现.

Answer 2

您的客户端发送字符串"GET".您只想发送和接收图像数据,"GET"不是图像数据.

您可能有其他错误,如果不了解您的协议,很难说.例如,一方如何知道它获得了所有图像数据？

Answer 3

编辑部分下面的代码对我来说似乎不错。我完全同意@David Schwartz 的观点。如果您想要实现一个协议，您必须考虑有关协议设计的很多事情。前任：

• 如果您发送命令，服务器如何反应
• 允许哪些命令
• 实现服务器响应的错误代码等

为此，您可以阅读《TCP/IP 和 Linux 协议实现》，这是一本关于此类问题的好书。

另一方面，您可以坚持基础知识并继续使用 TCP 套接字，我的拙见是您实现一些机制让客户端知道它是否具有完整的信息，例如：

• 发送数据的哈希值，在客户端检查哈希值
• 将信息切成块并发送块数量，然后在客户端检查收到了多少块，并在失败时重新请求图像
• 或以上全部