from target_simulator.core.sfp_transport import SfpTransport
from target_simulator.core.sfp_structures import SFPHeader


def test_small_packet_ignored():
    s = SfpTransport("127.0.0.1", 0, {})
    # pass empty data
    s._process_packet(b"", ("1.2.3.4", 1000))


def test_bad_header_handled(monkeypatch):
    s = SfpTransport("127.0.0.1", 0, {})
    # craft short data smaller than header
    s._process_packet(b"123", ("1.2.3.4", 1000))


def test_buffer_overflow_logged():
    s = SfpTransport("127.0.0.1", 0, {})
    # Build a header with tiny total_size but offset/pl_size that would overflow
    hdr = bytearray(SFPHeader.size())
    hdr[SFPHeader.get_field_offset("SFP_FLOW")] = ord("M")
    hdr[SFPHeader.get_field_offset("SFP_TID")] = 1
    hdr[SFPHeader.get_field_offset("SFP_TOTFRGAS")] = 1
    hdr[SFPHeader.get_field_offset("SFP_TOTSIZE")] = 1
    hdr[SFPHeader.get_field_offset("SFP_PLSIZE")] = 10
    hdr[SFPHeader.get_field_offset("SFP_PLOFFSET")] = 0
    data = bytes(hdr) + b"1234567890"
    s._process_packet(data, ("1.2.3.4", 1000))