传说中只用了十五行Python语句的P2P客户端/服务端 [转]

ice_cube

#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])]    # 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.