Question

我是python套接字编程的新手。我想将5个文件（照片）从mininet中的一台主机传输到另一台主机。这些文件的名称分别编号（我的意思是1.jpg，2.jpg和...）。问题是，当我运行这些代码时，第一张照片已正确传输，但其他照片已损坏。有什么问题：

sender.py

import socket
import sys

buf = 1024

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(('10.0.0.1',12345))

for i in range(1,6):
    with open("%d.jpg" % (i),'rb') as f:
        data = f.read(buf)
        while 1:
            if not data:
                break
            s.sendall(data)
            data = f.read(buf)
s.close()

receiver.py：

import socket
import sys

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(('10.0.0.1', 12345))

buf = 1024

s.listen(1)
conn , addr = s.accept()
for i in range(6,11):
    with open("%d.jpg" % (i),'wb') as f:
        while 1:
            data = conn.recv(buf)
            #print(data[:10])
            #print "PACKAGE RECEIVED..."
            f.write(data)
            if not data: break
#conn.close()
#s.close()

Answer 1

解决您问题的简单方法是为每个文件创建一个新连接。下面的代码可以做到这一点。

发件人

from __future__ import print_function
import socket

HOST = 'localhost'
PORT = 12345
BUFSIZE = 4096

def send_file(fname):
    with open(fname, 'rb') as f:
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        try:
            sock.connect((HOST, PORT))
        except socket.error as err:
            print(err, HOST, PORT)
            sock.close()
            return

        while True:
            data = f.read(BUFSIZE)
            if not data:
                break
            while data:
                sent = sock.send(data)
                data = data[sent:]

    sock.close()

fnames = [
    'test0.jpg',
    'test1.jpg',
    'test2.jpg',
    'test3.jpg',
]

def main():
    for fname in fnames:
        send_file(fname)

if __name__ == '__main__':
    main()

接收器

from __future__ import print_function
import socket

HOST = 'localhost'
PORT = 12345
BUFSIZE = 4096

class Receiver:
    ''' Buffer binary data from socket conn '''
    def __init__(self, conn):
        self.conn = conn
        self.buff = bytearray()

    def get(self, size):
        ''' Get size bytes from the buffer, reading
            from conn when necessary 
        '''
        while len(self.buff) < size:
            data = self.conn.recv(BUFSIZE)
            if not data:
                break
            self.buff.extend(data)
        # Extract the desired bytes
        result = self.buff[:size]
        # and remove them from the buffer
        del self.buff[:size]
        return bytes(result)

    def save(self, fname):
        ''' Save the remaining bytes to file fname '''
        with open(fname, 'wb') as f:
            if self.buff:
                f.write(bytes(self.buff))
            while True:
                data = self.conn.recv(BUFSIZE)
                if not data:
                    break
                f.write(data)

def main():
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    try:
        sock.bind((HOST, PORT))
    except socket.error as err:
        print('Bind failed', err)
        return

    sock.listen(1)
    print('Socket now listening at', HOST, PORT)
    file_number = 0
    try:
        while True:
            conn, addr = sock.accept()
            print('Connected with', *addr)

            fname = 'image%d.jpg' % file_number
            with open(fname, 'wb') as f:
                while True:
                    data = conn.recv(BUFSIZE)
                    if not data:
                        break
                    f.write(data)
            conn.close()
            print(fname, 'saved\n')
            file_number += 1

    # Hit Break / Ctrl-C to exit
    except KeyboardInterrupt:
        print('\nClosing')

    sock.close()

if __name__ == '__main__':
    main()

您需要按 Ctrl C 或 Break （取决于您的操作系统）以退出接收器。

但是在接收器上使用这些数字文件名并不是很令人满意，因此我决定使其更为复杂。 :)在以下版本中，我们在文件数据之前发送文件名。这有点棘手，因为接收方需要将文件名与实际文件数据分开。如果每个socket.recv调用都对应一个socket.send调用，这很容易，但是不能保证会发生：接收到的字节可能与发送字节的方式不同。接收者需要缓冲字节，以便可以正确分解它们。有关详细信息，请参见Socket Programming HOWTO。

为了让接收者知道文件名的结尾，我们首先发送一个字节来编码文件名的长度。字节可以容纳0到255之间的数字，因此此代码不能处理的文件名超过此数目。在长度字节之后，我们发送使用UTF-8编码的文件名本身。然后，我们发送实际的文件内容。

接收器使用名为Receiver的类来处理缓冲。此类具有.get方法，我们可以使用该方法获取指定数量的字节。我们使用该方法来获取文件名的长度和文件名。然后，我们使用Receiver的.save方法将接收到的文件内容保存到新文件中。

这段代码有点混乱，因为它被设计为可以在Python 2和Python 3上以任意组合运行。如果仅适用于Python 3，那会更整洁。我将“ localhost”硬编码为主机名，因为我只有一台计算机，因此无法通过网络对其进行测试，但是我确信它可以在网络上正常工作。

这是发件人：

from __future__ import print_function
import socket
from struct import pack

HOST = 'localhost'
PORT = 12345
BUFSIZE = 4096

def send(sock, data):
    while data:
        sent = sock.send(data)
        data = data[sent:]

def send_file(fname):
    with open(fname, 'rb') as f:
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        try:
            sock.connect((HOST, PORT))
        except socket.error as err:
            print(err, HOST, PORT)
            sock.close()
            return

        # Send the file name length & the filename itself in one packet          
        send(sock, pack('B', len(fname)) + fname.encode())
        while True:
            data = f.read(BUFSIZE)
            if not data:
                break
            send(sock, data)

    sock.close()

fnames = [
    'test1.gif',
    'test2.jpg',
    'test3.png',
    'test4.pdf',
]

def main():
    for fname in fnames:
        send_file(fname)

if __name__ == '__main__':
    main()

这是接收者：

from __future__ import print_function
import socket
from struct import unpack

HOST = 'localhost'
PORT = 12345
BUFSIZE = 4096

class Receiver:
    ''' Buffer binary data from socket conn '''
    def __init__(self, conn):
        self.conn = conn
        self.buff = bytearray()

    def get(self, size):
        ''' Get size bytes from the buffer, reading
            from conn when necessary 
        '''
        while len(self.buff) < size:
            data = self.conn.recv(BUFSIZE)
            if not data:
                break
            self.buff.extend(data)
        # Extract the desired bytes
        result = self.buff[:size]
        # and remove them from the buffer
        del self.buff[:size]
        return bytes(result)

    def save(self, fname):
        ''' Save the remaining bytes to file fname '''
        with open(fname, 'wb') as f:
            if self.buff:
                f.write(bytes(self.buff))
            while True:
                data = self.conn.recv(BUFSIZE)
                if not data:
                    break
                f.write(data)

def main():
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    try:
        sock.bind((HOST, PORT))
    except socket.error as err:
        print('Bind failed', err)
        return

    sock.listen(1)
    print('Socket now listening at', HOST, PORT)
    try:
        while True:
            conn, addr = sock.accept()
            print('Connected with', *addr)
            # Create a buffer for this connection
            receiver = Receiver(conn)
            # Get the length of the file name
            name_size = unpack('B', receiver.get(1))[0] 
            # Get the file name itself
            name = receiver.get(name_size).decode()
            print('name', name)
            # Save the file
            receiver.save(name)
            conn.close()
            print('saved\n')
    # Hit Break / Ctrl-C to exit
    except KeyboardInterrupt:
        print('\nClosing')

    sock.close()

if __name__ == '__main__':
    main()

Answer 2

您应该像这样使用它：

   with open("%d.jpg" % (i),'wb') as f:
        while 1:
            data = conn.recv(buf)
            #print(data[:10])
            #print "PACKAGE RECEIVED..."
            f.write(data)
            if not data: break

这样，当您退出 while 时离开 with 块时，f将自动关闭。

我想您需要扩展协议，以便接收方知道它所得到的，并且可以让它对它采取行动。类似于“传输开始”……发送文件名，发送数据，发送“传输结束”，使接收者关闭文件

将多个文件从一台主机传输到另一台主机

2 个答案:

发件人

接收器