Lib.py 文件源码

def addname(self, name):
        # Domain name packing (section 4.1.4)
        # Add a domain name to the buffer, possibly using pointers.
        # The case of the first occurrence of a name is preserved.
        # Redundant dots are ignored.
        list = []
        for label in string.splitfields(name, '.'):
            if label:
                if len(label) > 63:
                    raise PackError('label too long')
                list.append(label)
        keys = []
        for i in range(len(list)):
            key = string.upper(string.joinfields(list[i:], '.'))
            keys.append(key)
            if key in self.index:
                pointer = self.index[key]
                break
        else:
            i = len(list)
            pointer = None
        # Do it into temporaries first so exceptions don't
        # mess up self.index and self.buf
        buf = ''
        offset = len(self.buf)
        index = []
        for j in range(i):
            label = list[j]
            n = len(label)
            if offset + len(buf) < 0x3FFF:
                index.append((keys[j], offset + len(buf)))
            else:
                print 'DNS.Lib.Packer.addname:',
                print 'warning: pointer too big'
            buf = buf + (chr(n) + label)
        if pointer:
            buf = buf + pack16bit(pointer | 0xC000)
        else:
            buf = buf + '\0'
        self.buf = self.buf + buf
        for key, value in index:
            self.index[key] = value