ipsec.py 文件源码

def _encrypt_esp(self, pkt, seq_num=None, iv=None):

        if iv is None:
            iv = self.crypt_algo.generate_iv()
        else:
            if len(iv) != self.crypt_algo.iv_size:
                raise TypeError('iv length must be %s' % self.crypt_algo.iv_size)

        esp = _ESPPlain(spi=self.spi, seq=seq_num or self.seq_num, iv=iv)

        if self.tunnel_header:
            tunnel = self.tunnel_header.copy()

            if tunnel.version == 4:
                del tunnel.proto
                del tunnel.len
                del tunnel.chksum
            else:
                del tunnel.nh
                del tunnel.plen

            pkt = tunnel.__class__(str(tunnel / pkt))

        ip_header, nh, payload = split_for_transport(pkt, socket.IPPROTO_ESP)
        esp.data = payload
        esp.nh = nh

        esp = self.crypt_algo.pad(esp)
        esp = self.crypt_algo.encrypt(esp, self.crypt_key)

        self.auth_algo.sign(esp, self.auth_key)

        if self.nat_t_header:
            nat_t_header = self.nat_t_header.copy()
            nat_t_header.chksum = 0
            del nat_t_header.len
            if ip_header.version == 4:
                del ip_header.proto
            else:
                del ip_header.nh
            ip_header /= nat_t_header

        if ip_header.version == 4:
            ip_header.len = len(ip_header) + len(esp)
            del ip_header.chksum
            ip_header = ip_header.__class__(str(ip_header))
        else:
            ip_header.plen = len(ip_header.payload) + len(esp)

        # sequence number must always change, unless specified by the user
        if seq_num is None:
            self.seq_num += 1

        return ip_header / esp