bug: `From` and `Source` fields are always the same

[erhant]

Ever since we did the changes below:

• instead of looping all addresses in info.listen_addrs we simply use info.observed_addr
• fixed the add_explicit_peer on all peers (which caused memory issues)

the propagation source and message source turn out to be the same.

This is not really expected imo, and this way have to do with the problem in #119 as well since that also started after this change.

[erhant]

This could be related to Permissive setting as well, in which case we can close the issue

[erhant]

this is indeed due to new MessageAuthentication scheme that we are using, without signatures

the signatures are handled at app-level but not protocol level