External property on kCBLDatabaseChangeNotification when CBL is remote

[jamesnocentini]

Steps to reproduce:

1. Device A starts the Listener to enable CBL to become a remote in a replication
2. Start a push replication from another db to the CBL Listener (the target)
3. The changes being pushed and posted in the kCBLDatabaseChangeNotification handler always have a source URL that's null and external is false

When the replication is CBL <-> Sync Gateway, the external field has the expected value but when CBL becomes the remote it's always false on the database event.

[snej]

Turns out this is already hooked up, via the CBLRouter.source property which gets set by CBLHTTPConnection httpResponseForMethod:URI:. But it only gets set if the connection is authenticated as a user. This must be because I'm setting the value of source to a fake URL that looks like user:username.

[snej]

I could use user: (with no username) for the anonymous case.

For bonus points I could also append the socket's peer IP address, like user:username@66.66.66.66.

[borrrden]

I think there is still one path that will not show up correctly. If you put an attachment through the REST API, it will create a new revision of a document with isExternal set to NO because it takes the putRevision path instead of the forceInsert path:

https://github.com/couchbase/couchbase-lite-ios/blob/master/Source/CBL_Router+Handlers.m#L1083
https://github.com/couchbase/couchbase-lite-ios/blob/master/Source/CBL_Router+Handlers.m#L1039
https://github.com/couchbase/couchbase-lite-ios/blob/master/Source/CBLDatabase+Attachments.m#L491
https://github.com/couchbase/couchbase-lite-ios/blob/master/Source/CBLDatabase+Insertion.m#L207

https://github.com/couchbase/couchbase-lite-ios/blob/master/Source/CBL_SQLiteStorage.m#L1725
AND
https://github.com/couchbase/couchbase-lite-ios/blob/master/Source/CBL_ForestDBStorage.mm#L1090

[borrrden]

Also if a bulk docs request comes in with new_edits = true

https://github.com/couchbase/couchbase-lite-ios/blob/master/Source/CBL_Router+Handlers.m#L285
https://github.com/couchbase/couchbase-lite-ios/blob/master/Source/CBL_Router+Handlers.m#L867

Note that the source is passed in but never used in either case