changes

早期freebsd实现

Previously it would expire after N retries to N' different servers, which
could be a very long time.  Particularly in the case of lame delegations and
other forwarding loops, we feel that 90 seconds (two max-retry intervals) is
enough time for a query to be answered.  While we were into this code we made
several fields in the query structure into "short"'s since they were only
being used to store smallish integers.  The query list gets Very Long during
a forwarding loop -- even 90 seconds worth of queries is a lot of queries.

This version includes my hacks that assign a "credibility index" to each
<name,type> such that when more credible data arrives for a given
<name,type>, all old data is purged.  When equally-credible data arrives it
is aggregated in the way we all know and love; when less credible data
arrives it is completely ignored.  Credibility, from best to worst, is:
	1. zone files (primary or secondary)
	2. authoritative answers
	3. non-authoritative answers and authority records
	4. additional data
	5. zone files ("cache" or "bootstrap" information)
You need this version of bind if you still show any A RR's in network
32.0.0.0 when you look up uucp-gw-1.pa.dec.com's A or adobe.com's NS.

I have also added some extra code to prevent pollution of the internal
"hint cache."  In all versions of BIND that I was able to test, any IN_A
response to any sysquery() would cause the IN_A RR to be added to the
fcachetab ("hint cache").  This resulted in lots of extra cruft in the hint
cache, that wasn't timed out properly, which in turn resulted in lots of
strange answers ('nuff said, take my word for it.)

Though changes have been made to make the Ultrix and GNU (2.1) C compilers
stop complaining about the source, it should still compile and run just
about anywhere.  In fact, after I cleaned up lots of old lint, this version
of BIND is known to compile and run on:

	Ultrix 4.2 (MIPS or VAX)
	SunOS 4.0.3
	BSD/386 (BSDi beta)

This was being released as King James Bind because, like KJ Sendmail, it is
a merge of every major variant of Bind that we know about.  It was
assembled and tested by Paul Vixie of DEC NSL/WRL, with generous donations
of code and advice from Win Treese of DEC CRL.  Changes from Don Lewis of
Harris, Andrew Partan of UUNET, and Piet Beertema of EUNet are also included.
See the OPTIONS file for a description of the changes you can control with
#ifdef's.

This server has been run on UUCP-GW-{1,2}.PA.DEC.COM, which are in the UUCP
Zone.  Our named.boot file has ~1900 lines in it.  Before we instituted the
changes in this release, our name server usually ran at about 16MB virtual,
15MB physical, growing slowly but constantly until we restarted it.
Whenever a new zone was added to the NIC's root zone listing us as a name
server, our servers would kill themselves and eachother (and NS.UU.NET, one
of the other UUCP Zone name servers) with forwarding loops.  After these
changes, we run at a fairly constant 8MB virtual and physical size, and our
apparent CPU utilization is always 0.0% since we never finish a quantum and
the scheduler always sees us as waiting for I-O.  In other words, life is good.

Notes from UCB version 4.8.3 follow:

-------------------

This is version 4.8.3 of bind.  It is a test release that updates
versions 4.8 and 4.8.1 with fixes, and is essentially the same as
the version of named on the 4.3BSD Reno release.  Although it is
currently described as a test release, it is believed to be reasonably
stable and more usable than the previously-released versions.
Here are some of the more important changes:

  o A list of domains may be specified for searching in resolv.conf instead
    of just the local domain name.

  o gethostbyname() will accept a dotted quad.

  o Support has been added for the the T_TXT data type and for the class
    C_HS.  These are both used by Hesiod from Project Athena at MIT.

  o All of the pathnames have been put into one header file.  This
    makes it easier to change the location based upon your local
    configuration.

  o Responses are only accepted from an address to which we might of sent
    the request.  This might cause problems if some server is multihomed
    and is still running BIND 4.3, but it prevents attacks induced by
    sending responses from another address.

  o Numerous bugs have been fixed:  Adding a new authoritative zone now
    works when the server has a cached SOA record.  Comparisons in the
    db now look at type and class as well instead of dropping records
    with identical data.  Scheduling of maintenance interrupts has been
    moved to one routine avoid spurious ones.  Named goes into the background
    after more of the initialization is done.  Stream connection queue
    handling was cleaned up including a bug that caused data corruption
    and core dumps.  Sys5 no longer can have multiple transfers of the
    same zone occuring at the same time.  Handle CNAME -> CNAME loops
    more gracefully.  Avoid making one server never get queried.  Border
    conditions in resolver are checked more accurately.

  o Nslookup has been updated.

There are several bug reports that have yet to be integrated into this
version.  Hopefully they will be dealt with in the next release.  Please
send feedback on this release.

Notes from versions 4.8.1 and 4.8 follow:

------------------

This is version 4.8.1 of bind.  It is a test release that includes
version 4.8 with fixes, asynchronous zone transfer and better reload
capabilities.  Although it is currently described as a test release,
it is believed to be reasonably stable and more usable than the currently-
released version, 4.8.  The changes of note are:

  o The asynchronous zone transfer code previously posted to the bind
    mailing list has been integrated, completed and tested.  There are
    a number of changes from the version posted, including fixes to
    allow top-level domains to work and a simplification of the timer
    code.

  o The code for reloading the server has been changed so that only
    primary zones master files that have changed are reloaded.  The
    cache and secondary zones are not flushed, and the sortlist, domain,
    etc. are reset to correspond to the boot file contents.

  o Several bugs have been fixed: the name "*" is not interpreted as
    a wildcard in cached zones, only in primary zones.  Secondary servers
    no longer decrement the time-to-live of records by the time since
    they verified the zone with the master; as a result, they never
    hand out nameserver referrals with too short a TTL to be usable.
    A bug was fixed that caused secondary servers with out-of-date
    zones to return empty answers between the actual expiration time
    and the next timeout.

There are several other bugs that have been reported but have not yet
been fixed.  In addition, the next regular release of named will
support negative caching, but this has not been integrated.

I would appreciate receiving feedback on this release; in particular,
problems (or lack of problems) when installing on various systems.
I attempted to update the SysV code when integrating the zone-transfer,
but haven't tested it.

The notes from version 4.8 follow.

----------
Welcome to version 4.8 of bind.

There have been several changes to the named boot file (/etc/named.boot)
of which you should be aware.  The "domain" line for each zone is no longer
needed, but one such line may still be used to specify a default domain
to be used for queries containing names with only a single component.
The term "suffixes", which was added in version 4.7alpha, has been removed.

The manual page on named (named.8) has been updated to reflect all
these changes.  Please read this and look at the example files
before installation.  You should also note the changes in the
resolver code to support non-fully-qualified addresses and per-user
host aliases.  See hostname(7) for an overview.  Two new routines
have been added to the resolver library since the last test release:
res_query formulates a query, sends it, waits for a response and does
preliminary error checking; res_search implements the search rules
of gethostbyname using res_query.

The MX lookup routine in sendmail has been modified to use res_search.  
Also, dn_skip takes an additional parameter and has been renamed
to dn_skipname.  While old sendmail binaries will work with the new
version of bind, because of these changes, it is desirable to install
new sendmail sources and recompile sendmail.  Do not rebuild sendmail 
from old sources.   The new sendmail is on ucbarpa.Berkeley.EDU for
anonymous FTP from pub/4.3/sendmail.MX.tar and pub/4.3/sendmail.MX.tar.Z.

There have been numerous changes to named, fixing most of the known
bugs that can be fixed without major structural changes in the server.
Several server configurations that failed before should now work.
Certain robustness problems have been fixed, in particular bounds-
checking when processing incoming packets.  Two changes have been made
in preparation for negative caching: SOA records are sent in the authority
section in negative responses with NXDOMAIN set, and a bug was fixed that
caused confusion and repeated requests if a response had no error, no answer
and an SOA in the authority section.  As such responses are already sent
by other servers, and will be sent by the next release of BIND, it is
important that all sites upgrade to this version as quickly as possible.

The root "hint" cache and cache file remain the largest problem area,
along with named's naivete in accepting bogus server's data.
These will be addressed in the next release, along with asynchronous
zone transfers, intelligent reloading of zone files, faster startup,
and caching of negative responses.

This version (4.8) will replace the last officially released version (4.5).
Version 4.5 has a serious bug that causes the generation of a continuous
stream of bogons to the root domain servers (bogus queries with the query
response bit set and possibly garbage for nsid and rcode).  It is imperative
that these versions of named be replaced as fast as possible.  We urge you to
field 4.8 quickly, for the sake of the root domain servers.

	Mike Karels
	Jean Wood
	[e-mail]

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