The additional processing method has been expanded to take the
owner name of the record, as HTTPS and SVBC need it to process "."
in service form.
The additional section callback can now return the RRset that was
added. We use this when adding CNAMEs. Previously, the recursion
would stop if it detected that a record you added already exists. With
CNAMEs this rule doesn't work, as you ultimately care about the RRset
at the target of the CNAME and not the presence of the CNAME itself.
Returning the record allows the caller to restart with the target
name. As CNAMEs can form loops, loop protection was added.
As HTTPS and SVBC can produce infinite chains, we prevent this by
tracking recursion depth and stopping if we go too deep.
getquad() was implemented back in 2001 to warn about IPv4 addresses in
non-dotted-quad form being used. As change 4900 (GL #13) removed all
uses of inet_aton(), which allowed such forms, with inet_pton(), which
does not allow them, there is no point in keeping getquad() around as it
now only prints an extra warning when the parser comes across an IP
address in a form which is not acceptable anyway. Replace all uses of
getquad() with inet_pton(AF_INET, ...).
