gopherlib.py

"""Gopher protocol client interface."""__all__ = ["send_selector","send_query"]# Default selector, host and portDEF_SELECTOR = '1/'DEF_HOST     = 'gopher.micro.umn.edu'DEF_PORT     = 70# Recognized file typesA_TEXT       = '0'A_MENU       = '1'A_CSO        = '2'A_ERROR      = '3'A_MACBINHEX  = '4'A_PCBINHEX   = '5'A_UUENCODED  = '6'A_INDEX      = '7'A_TELNET     = '8'A_BINARY     = '9'A_DUPLICATE  = '+'A_SOUND      = 's'A_EVENT      = 'e'A_CALENDAR   = 'c'A_HTML       = 'h'A_TN3270     = 'T'A_MIME       = 'M'A_IMAGE      = 'I'A_WHOIS      = 'w'A_QUERY      = 'q'A_GIF        = 'g'A_HTML       = 'h'          # HTML fileA_WWW        = 'w'          # WWW addressA_PLUS_IMAGE = ':'A_PLUS_MOVIE = ';'A_PLUS_SOUND = '<'_names = dir()_type_to_name_map = {}def type_to_name(gtype):    """Map all file types to strings; unknown types become TYPE='x'."""    global _type_to_name_map    if _type_to_name_map=={}:        for name in _names:            if name[:2] == 'A_':                _type_to_name_map[eval(name)] = name[2:]    if _type_to_name_map.has_key(gtype):        return _type_to_name_map[gtype]    return 'TYPE=' + `gtype`# Names for characters and stringsCRLF = '\r\n'TAB = '\t'def send_selector(selector, host, port = 0):    """Send a selector to a given host and port, return a file with the reply."""    import socket    if not port:        i = host.find(':')        if i >= 0:            host, port = host[:i], int(host[i+1:])    if not port:        port = DEF_PORT    elif type(port) == type(''):        port = int(port)    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)    s.connect((host, port))    s.send(selector + CRLF)    s.shutdown(1)    return s.makefile('rb')def send_query(selector, query, host, port = 0):    """Send a selector and a query string."""    return send_selector(selector + '\t' + query, host, port)def path_to_selector(path):    """Takes a path as returned by urlparse and returns the appropriate selector."""    if path=="/":        return "/"    else:        return path[2:] # Cuts initial slash and data type identifierdef path_to_datatype_name(path):    """Takes a path as returned by urlparse and maps it to a string.    See section 3.4 of RFC 1738 for details."""    if path=="/":        # No way to tell, although "INDEX" is likely        return "TYPE='unknown'"    else:        return type_to_name(path[1])# The following functions interpret the data returned by the gopher# server according to the expected type, e.g. textfile or directorydef get_directory(f):    """Get a directory in the form of a list of entries."""    list = []    while 1:        line = f.readline()        if not line:            print '(Unexpected EOF from server)'            break        if line[-2:] == CRLF:            line = line[:-2]        elif line[-1:] in CRLF:            line = line[:-1]        if line == '.':            break        if not line:            print '(Empty line from server)'            continue        gtype = line[0]        parts = line[1:].split(TAB)        if len(parts) < 4:            print '(Bad line from server:', `line`, ')'            continue        if len(parts) > 4:            if parts[4:] != ['+']:                print '(Extra info from server:',                print parts[4:], ')'        else:            parts.append('')        parts.insert(0, gtype)        list.append(parts)    return listdef get_textfile(f):    """Get a text file as a list of lines, with trailing CRLF stripped."""    list = []    get_alt_textfile(f, list.append)    return listdef get_alt_textfile(f, func):    """Get a text file and pass each line to a function, with trailing CRLF stripped."""    while 1:        line = f.readline()        if not line:            print '(Unexpected EOF from server)'            break        if line[-2:] == CRLF:            line = line[:-2]        elif line[-1:] in CRLF:            line = line[:-1]        if line == '.':            break        if line[:2] == '..':            line = line[1:]        func(line)def get_binary(f):    """Get a binary file as one solid data block."""    data = f.read()    return datadef get_alt_binary(f, func, blocksize):    """Get a binary file and pass each block to a function."""    while 1:        data = f.read(blocksize)        if not data:            break        func(data)def test():    """Trivial test program."""    import sys    import getopt    opts, args = getopt.getopt(sys.argv[1:], '')    selector = DEF_SELECTOR    type = selector[0]    host = DEF_HOST    if args:        host = args[0]        args = args[1:]    if args:        type = args[0]        args = args[1:]        if len(type) > 1:            type, selector = type[0], type        else:            selector = ''            if args:                selector = args[0]                args = args[1:]        query = ''        if args:            query = args[0]            args = args[1:]    if type == A_INDEX:        f = send_query(selector, query, host)    else:        f = send_selector(selector, host)    if type == A_TEXT:        list = get_textfile(f)        for item in list: print item    elif type in (A_MENU, A_INDEX):        list = get_directory(f)        for item in list: print item    else:        data = get_binary(f)        print 'binary data:', len(data), 'bytes:', `data[:100]`[:40]# Run the test when run as scriptif __name__ == '__main__':    test()