If you have a bot connected to the hub, and you want to add a user
command to interact with the bot via PM, you need to know its session ID
(SID). However, SIDs are assigned when the client first connects, prior
to the nickname being sent, and so we cannot just assign a certain SID
based on the nickname as part of the connection routine.
To overcome this, this commit adds the ability to reserve the first few
SIDs (at hub start time, when the SIDs are known) for certain nicknames.
The user manager then checks each time a user logs in to see if the
nickname matches a reserved one, and if so sets up an alias from the
reserved SID to the SID the user was given. This alias is only checked
for private messages (the ADC DMSG or EMSG commands) which are routed to
the real user. Any other commands are ignored as there should be no need
for such aliasing.
The list of nicknames to reserve SIDs for is read from a space-separated
list in the reserved_sids parameter of the config file. The reserved
users must also be registered users (i.e., given a password) -- if they
are not, the alias is not set up for them.
Rewrote patches from Zoltan to support ip ranges and multiple results per IP.
Needed to make sure IPv6 mapped IPv4 addresses were converted to proper IPv4 addresses after accept().
