teredo: be stricter on what to consider valid teredo

Invalid Teredo can lead to valid DNS traffic (or other UDP traffic)
being misdetected as Teredo. This leads to false negatives in the
UDP payload inspection.

Make the teredo code only consider a packet teredo if the encapsulated
data was decoded without any 'invalid' events being set.

Bug #2736.
static int DecodeIPV6HopTest01 (void)
{
    uint8_t raw_pkt1[] = {
        0x60,0x00,0x00,0x00,0x00,0x20,0x00,0x01,0xfe,0x80,0x00,0x00,0x00,0x00,0x00,0x00,
        0x02,0x0f,0xfe,0xff,0xfe,0x98,0x3d,0x01,0xff,0x02,0x00,0x00,0x00,0x00,0x00,0x00,
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x3a,0x00,0xff, /* 0xff is a nonsene opt */
        0x02,0x00,0x00,0x00,0x00,
        0x82,0x00,0x1c,0x6f,0x27,0x10,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
    };
    Packet *p1 = PacketGetFromAlloc();
    FAIL_IF(unlikely(p1 == NULL));
    ThreadVars tv;
    DecodeThreadVars dtv;
    PacketQueue pq;

    FlowInitConfig(FLOW_QUIET);

    memset(&pq, 0, sizeof(PacketQueue));
    memset(&tv, 0, sizeof(ThreadVars));
    memset(&dtv, 0, sizeof(DecodeThreadVars));

    PacketCopyData(p1, raw_pkt1, sizeof(raw_pkt1));

    DecodeIPV6(&tv, &dtv, p1, GET_PKT_DATA(p1), GET_PKT_LEN(p1), &pq);

    FAIL_IF (!(ENGINE_ISSET_EVENT(p1, IPV6_HOPOPTS_UNKNOWN_OPT)));

    PACKET_RECYCLE(p1);
    SCFree(p1);
    FlowShutdown();
    PASS;
}

static int DecodeIPV6HopTest01 (void)
{
    uint8_t raw_pkt1[] = {
        0x60,0x00,0x00,0x00,0x00,0x20,0x00,0x01,0xfe,0x80,0x00,0x00,0x00,0x00,0x00,0x00,
        0x02,0x0f,0xfe,0xff,0xfe,0x98,0x3d,0x01,0xff,0x02,0x00,0x00,0x00,0x00,0x00,0x00,
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x3a,0x00,0xff, /* 0xff is a nonsene opt */
        0x02,0x00,0x00,0x00,0x00,
        0x82,0x00,0x1c,0x6f,0x27,0x10,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
    };
    Packet *p1 = PacketGetFromAlloc();
    FAIL_IF(unlikely(p1 == NULL));
    ThreadVars tv;
    DecodeThreadVars dtv;
    PacketQueue pq;

    FlowInitConfig(FLOW_QUIET);

    memset(&pq, 0, sizeof(PacketQueue));
    memset(&tv, 0, sizeof(ThreadVars));
    memset(&dtv, 0, sizeof(DecodeThreadVars));

    PacketCopyData(p1, raw_pkt1, sizeof(raw_pkt1));

    DecodeIPV6(&tv, &dtv, p1, GET_PKT_DATA(p1), GET_PKT_LEN(p1), &pq);

    FAIL_IF (!(ENGINE_ISSET_EVENT(p1, IPV6_HOPOPTS_UNKNOWN_OPT)));

    PACKET_RECYCLE(p1);
    SCFree(p1);
    FlowShutdown();
    PASS;
}
