Realm Hook
Realm's flexible hooks.
Pre-connect Hook
// Get the required length of first packet.
uint32_t ;
// Get the index of the selected remote peer.
//
// Remote peers are defined in `remote`(default) and `extra_remotes`(extended),
// where there should be at least 1 remote peer whose idx is 0.
//
// idx < 0 means **ban**.
// idx = 0 means **default**.
int32_t ;