from trex_stl_lib.api import *
from scapy.contrib.mpls import * # import from contrib folder of scapy 


class STLS1(object):

    def __init__ (self):
        pass;

    def create_stream (self):
        # 2 MPLS label the internal with  s=1 (last one)
        pkt =  Ether()/MPLS(label=17,cos=1,s=0,ttl=255)/MPLS(label=0,cos=1,s=1,ttl=12)/IP(src="16.0.0.1",dst="48.0.0.1")/UDP(dport=12,sport=1025)/('x'*20)

        vm = CTRexScRaw( [ STLVmFlowVar(name="mlabel", min_value=1, max_value=2000, size=2, op="inc"), # 2 bytes var
                           STLVmWrMaskFlowVar(fv_name="mlabel", pkt_offset= "MPLS:1.label",pkt_cast_size=4, mask=0xFFFFF000,shift=12) # write to 20bit MSB
                          ]
                       )

        # burst of 100 packets
        return STLStream(packet = STLPktBuilder(pkt = pkt ,vm = vm),
                         mode = STLTXSingleBurst( pps = 1, total_pkts = 100) )


    def get_streams (self, direction = 0):
        # create 1 stream 
        return [ self.create_stream() ]

def register():
    return STLS1()