TinyP2P如何运行 How tinyp2p works!

TinyP2P被誉为世界上最小的P2P应用，只用15行Python代码实现。

然而在实际使用过程中，却会遇到一些问题，下面来看看这段神奇的代码。

这是一段在网上十分流行的经过别人注释的代码：

#zz from http://www.exonsoft.com/~kochin/TinyP2P/tinyp2p.html# tinyp2p.py 1.0 (documentation at http://freedom-to-tinker.com/tinyp2p.html)# (C) 2004, E.W. Felten# license: http://creativecommons.org/licenses/by-nc-sa/2.0# Annotated by Kochin Chang, Jan. 2005# Usage:#   Server - python tinyp2p.py password server hostname  portnum [otherurl]#   Client - python tinyp2p.py password client serverurl pattern#                   ar[0]      ar[1]    ar[2]  ar[3]     ar[4]   ar[5]import sys, os, SimpleXMLRPCServer, xmlrpclib, re, hmac# Import libraries used in the program.# sys : system variables and functions.# os : portable OS dependent functionalities.# SimpleXMLRPCServer : basic XML-RPC server framework.# xmlrpclib : XML-RPC client support.# re : regular expression support.# hmac : RFC 2104 Keyed-Hashing Message Authentication.ar,pw,res = (sys.argv,lambda u:hmac.new(sys.argv[1],u).hexdigest(),re.search)# A multiple assignment.# ar <- sys.argv : the argument list.# pw <- lambda u:hmac.new(sys.argv[1],u).hexdigest() :#   a function makes an HMAC digest from a URL.#   INPUT: a string, u, which is a URL here.#   OUTPUT: a hexdecimal HMAC digest.#   DESCRIPTION:#     1. Creates a HMAC object from the URL using network's password,#        sys.argv[1], as the key.#     2. Returns a hexdecimal digest of the HMAC object.# res <- re.search : alias for the regular expression search function.pxy,xs = (xmlrpclib.ServerProxy,SimpleXMLRPCServer.SimpleXMLRPCServer)# A multiple assignment.# pxy <- xmlrpclib.ServerProxy : alias for the ServerProxy class.# xs <- SimpleXMLRPCServer.SimpleXMLRPCServer : alias for the SimpleXMLRPCServer class.def ls(p=""):return filter(lambda n:(p=="")or res(p,n),os.listdir(os.getcwd()))# a function lists directory entries.# INPUT: a string, p, which is a regular expression pattern.# OUTPUT: a list of directory entries matched the pattern.# DESCRIPTION:#   1. Creates a function using lambda expression that takes a pathname as its#      parameter. The function returns true if the pattern is empty or the#      pathname matches the pattern.#   2. Finds out what is the current working directory.#   3. Retrieves a list of directory entries of current working directory.#   4. Filters the list using the lambda function defined.if ar[2]!="client":# Running in server mode...   myU,prs,srv = ("http://"+ar[3]+":"+ar[4], ar[5:],lambda x:x.serve_forever())  # A multiple assignment.  # myU <- "http://"+ar[3]+":"+ar[4] : server's own URL.  # prs <- ar[5:] : URL's of other servers in the network.  # srv <- lambda x:x.serve_forever() :  #   a function to start a SimpleXMLRPCServer.  #   INPUT: a SimpleXMLRPCServer object, x.  #   OUTPUT: (none)  #   DESCRIPTION:  #     Calls the server's serve_forever() method to start handling request.   def pr(x=[]): return ([(y in prs) or prs.append(y) for y in x] or 1) and prs  # a function returns the server list.  # INPUT: a list, x, of servers' URLs to be added to the server list.  # OUTPUT: the updated server list.  # DESCRIPTION:  #   1. For each URL in x, checks whether it's already in the server list.  #      If it's not in the list, appends in onto the list.  #   2. Returns the updated server list.   def c(n): return ((lambda f: (f.read(), f.close()))(file(n)))[0]  # a function returns content of the specified file.  # INPUT: a string, n, which is a filename.  # OUTPUT: the content of the file in a string.  # DESCRIPTION:  #   1. Creates a function using lambda expression that takes a file object, f,  #      as its parameter. The function reads the content of the file, then  #      closes it. The results of the read and close are put into a tuple, and  #      the tuple is returned.  #   2. Creates a file object with the filename. Passes it to the lambda  #      function.  #   3. Retrieves and returns the first item returned from the lambda function.   f=lambda p,n,a:(p==pw(myU))and(((n==0)and pr(a))or((n==1)and [ls(a)])or c(a))  #   a request handling function, depending on the mode, returns server list,  #   directory entries, or content of a file.  #   INPUT: a string, p, which is a hexdecimal HMAC digest.  #          a mode number, n.  #          if n is 0, a is a list of servers to be added to server list.  #          if n is 1, a is a pattern string.  #          if n is anything else, a is a filename.  #   OUTPUT: if n is 0, returns the server list.  #           if n is 1, returns directory entries match the pattern.  #           if n is anything else, returns content of the file.  #   DESCRIPTION:  #     1. Verifies the password by comparing the HMAC digest received and the  #        one created itself. Continues only when they match.  #     2. If n is 0, calls pr() to add list, a, and returns the result.  #        If n is 1, calls ls() to list entries match pattern a, and returns  #        the result enclosed in a list.  #        If n is any other value, retreives and return content of the file  #        with filename specified in a.   def aug(u): return ((u==myU) and pr()) or pr(pxy(u).f(pw(u),0,pr([myU])))  # a function augments the network.  # INPUT: a string, u, which is a URL.  # OUTPUT: a list of URL's of servers in the network.  # DESCRIPTION:  #   1. If the URL, u, equals to my own URL, just returns the server list.  #   2. Otherwise, creates a ServerProxy object for server u. Then calls its  #      request handling function f with a HMAC digest, mode 0, and server  #      list with myself added.  #   3. Calls pr() with the result returned from server u to add them to my  #      own list.  #   4. Returns the new list.   pr() and [aug(s) for s in aug(pr()[0])] or pr([myU])  # 1. Checks the server list is not empty.  # 2. Takes the first server on the list. Asks that server to augment its  #    server list with my URL.  # 3. For each server on the returned list, asks it to add this server to its  #    list.   (lambda sv:sv.register_function(f,"f") or srv(sv))(xs((ar[3],int(ar[4]))))  # Starts request processing.  # 1. Defines a function with lambda expression that takes a SimpleXMLRPCServer  #    object, registers request handling function, f, and starts the server.  # 2. Creates a SimpleXMLRPCServer object using hostname (ar[3]) and portnum  #    (ar[4]). Then feeds the object to the lambda function. # Running in client mode...for url in pxy(ar[3]).f(pw(ar[3]),0,[]):# 1. Create a ServerProxy object using the serverurl (ar[3]).# 2. Calls the remote server and retrieves a server list.# 3. For each URL on the list, do the following:  for fn in filter(lambda n:not n in ls(), (pxy(url).f(pw(url),1,ar[4]))[0]):  # 1. Create a ServerProxy object using the URL.  # 2. Calls the remote server to return a list of filenames matching the  #    pattern (ar[4]).  # 3. For each filename doesn't exist locally, do the following:     (lambda fi:fi.write(pxy(url).f(pw(url),2,fn)) or fi.close())(file(fn,"wc"))    # 1. Define a lambda function that takes a file object, calls remote server    #    for the file content, then closes the file.    # 2. Create a file object in write and binary mode with the filename. (I    #    think the mode "wc" should be "wb".)    # 3. Passes the file object to the lambda function.

其运行方法也很容易从网上找到：

服务器：python tinyp2p.py  123456 server 127.0.0.1 12345
客户端：python tinyp2p.py 123456 client http://127.0.0.1:12345 hello.py

运行服务器，需要配置密码、ip、端口。

运行客户端，需要配置和服务器已保存的密码、ip、端口，最后一个参数是要下载的文件名（本机上测试时该文件应该在服务器源代码文件所在路径下）。

然后就是这样一段广为流传的代码却有两个问题。

1. 作为服务器可以正常运行，作为客户端不能正常运行，会报如下的错误：

File "tinyp2p.py", line 14, in ?for url in pxy(ar[3]).f(pw(ar[3]),0,[]):File "/usr/lib/python2.4/xmlrpclib.py", line 1096, in __call__return self.__send(self.__name, args)File "/usr/lib/python2.4/xmlrpclib.py", line 1383, in __requestverbose=self.__verboseFile "/usr/lib/python2.4/xmlrpclib.py", line 1147, in requestreturn self._parse_response(h.getfile(), sock)File "/usr/lib/python2.4/xmlrpclib.py", line 1286, in _parse_responsereturn u.close()File "/usr/lib/python2.4/xmlrpclib.py", line 744, in closeraise Fault(**self._stack[0])xmlrpclib.Fault: <Fault 1: 'exceptions.TypeError:coercing to Unicode:need string or buffer, list found'>

解决的办法是修改代码（不含注释）的第11行：

pr() and [aug(s) for s in aug(pr()[0])]topr() and [aug(s) for s in aug(pr()[0])] or pr([myU])

2.只能传输小于10KB的文件

传输超过10KB的文件，会报如下的错误：

Traceback (most recent call last):  File "tinyp2p.py", line 22, in <module>    (lambda fi:fi.write(pxy(url).f(pw(url),2,fn)) or fi.close())(file(fn,"wc"))  File "tinyp2p.py", line 22, in <lambda>    (lambda fi:fi.write(pxy(url).f(pw(url),2,fn)) or fi.close())(file(fn,"wc"))  File "C:\Program Files (x86)\Python27\lib\xmlrpclib.py", line 1224, in __call__    return self.__send(self.__name, args)  File "C:\Program Files (x86)\Python27\lib\xmlrpclib.py", line 1578, in __request    verbose=self.__verbose  File "C:\Program Files (x86)\Python27\lib\xmlrpclib.py", line 1264, in request    return self.single_request(host, handler, request_body, verbose)  File "C:\Program Files (x86)\Python27\lib\xmlrpclib.py", line 1297, in single_request    return self.parse_response(response)  File "C:\Program Files (x86)\Python27\lib\xmlrpclib.py", line 1467, in parse_response    p.feed(data)  File "C:\Program Files (x86)\Python27\lib\xmlrpclib.py", line 557, in feed    self._parser.Parse(data, 0)xml.parsers.expat.ExpatError: not well-formed (invalid token): line 5, column 17

这个暂时还没找到解决方法。