TinyRPL Bug Fix

[Hyungsin]

I have evaluated TinyRPL for some years and found out some bugs, which cause malfunction.
This pull request is simply reporting these bugs.

1. RPLDAORoutingEngineP.nc

• A node must set "new_key" even when receiving a DAO from an existing entry, which enables to reset "path_lifetime". If not, each entry in the downlink routing table will be always removed after the initial path_lifetime.

2. RPLOF0P.nc

• Here, "min" value should be increased when a target entry is not a valid parent. However, the current "IF" conditions cannot tell if the entry is valid or not.

3. RPLRankP.nc

• "INIT_ETX" is not a pure ETX but ETX * divideRank. "tempEtx_hop" also has divideRank in it.
  So, we should replace "BLIP_L2_RETRIES" to BLIP_L2_RETRIES*divideRank for fairness.

[Hyungsin]

Any review?

[cire831]

I don't have the expertise to review this. But ... have you tested this sufficiently?

How much testing have you done on this?

[Hyungsin]

I tested many times and published several papers with this fix.

1. https://ieeexplore.ieee.org/abstract/document/7500119/
2. https://dl.acm.org/citation.cfm?id=2809717
3. https://dl.acm.org/citation.cfm?id=2983532
4. https://ieeexplore.ieee.org/abstract/document/7387272/

[gnawali]

Not able to test but I will chat with you on Skype to go through the change one by one and then approve. Lets do it this week.

[Hyungsin]

Ok. When is good for you?