The goal here is to help new or infrequent users figure out the most
basic ways to use dig.
Notes on the choice of examples:
* I wrote examples that users can copy and paste exactly as is, without
having to come up with an appropriate IP address or domain name to use.
The one exception is the `dig -x` example which uses an IP from the
example range.
* `dig +noall +answer` here is because learning about `+noall +answer`
was lifechanging for me when I learned about it, I've heard from
others that they find it helpful too, and it's pretty hard to infer
from the man page as is that it might be useful
* I thought about adding `+trace` but left it out because 5 examples was
already starting to feel like a lot.
CLEANUP is a macro similar to CHECK but unconditional, jumping
to cleanup even if the result is ISC_R_SUCCESS. It is now used
in place of DST_RET, CLEANUP_WITH, and CHECK(<non-success constant>).
now that the EDNS state is stored within dns_message_t, it's no longer
necessary to have a public API call to build an opt rdataset; we can
just have dns_message_setopt() build the opt record internally.
The new dns_message_ednsinit() and dns_message_ednsaddopt() functions
allow EDNS options to be added to a message one at a time; it is no
longer necessary to construct a full array of EDNS options and set
them all at once.
This allows us to simplify EDNS option handling code, and in the
future it wlil allow plugins to add EDNS options to existing
messages.
Previously, if there's no more server to try in force_next,
it attempted to retry the current server similar to a query
timeout case. But, force_next() is called only when the
current server's address is unusable and the query was not
even sent, so recvcount was not incremented, causing an
assertion failure.
We might be able to fix it so the retry doesn't cause a crash,
but it doesn't make sense to retry the server when its address
is known to be unusable. So, simply avoiding the retry would be
the easiest and safest way to prevent the crash.
Without this, start_udp or start_tcp would trigger an assertion
failure. Detaching it at this point is also consistent with
other failure handling cases, such as in recv_done.
Instead of (1) allocating a parser, (2) parsing a file/buffer then (3)
freeing the parser, the parser is now internally created/destroyed from
within the `cfg_parse_*` functions. This simplifies a lot the use cases,
especially around the error cases where the parser needs to be freed in
a cleanup goto.
The only trick was the parser callback mechanism, which would previously
have been set up between steps 1 and 2. Since it's never been used for
any purpose other than the "directory" option, the chdir call has now
been moved inside the parser and the generic callback mechanism has been
removed, replacing CFG_CLAUSEFLAG_CALLBACK with CFG_CLAUSEFLAG_CHDIR.
cfg_obj_t doesn't store a pointer to its a parser context anymore,
and does not depend on the parser's lifecycle. Instead, it stores a
reference to its own memory context (and in principle, each node
could have different memory context). This also slightly simplifies
the _destroy API as there is no need to pass a context through it
anymore.
> Put a space before opening parentheses only after control statement
> keywords (for/if/while...) except this option doesn’t apply to ForEach
> and If macros. This is useful in projects where ForEach/If macros are
> treated as function calls instead of control statements.
This required couple of internal changes to the isc_mem_debugging.
The isc_mem_debugging is now internal to isc_mem unit and there are
three new functions:
1. isc_mem_setdebugging() can change the debugging setting for an
individual memory context. This is need for the memory contexts used
for OpenSSL, libxml and libuv accounting as recording and tracing
memory is broken there.
2. isc_mem_debugon() / isc_mem_debugoff() can be used to change default
memory debugging flags as well as debugging flags for isc_g_mctx.
Additionally, the memory debugging is inconsistent across the code-base.
For now, we are keeping the existing flags, but three new environment
variables have been added 'ISC_MEM_DEBUGRECORD', 'ISC_MEM_DEBUGTRACE'
and 'ISC_MEM_DEBUGUSAGE' to set the global debugging flags at any
program using the memory contexts.
Instead of having individual memory contexts scattered across different
files and called different names, add a single memory context called
isc_g_mctx that replaces named_g_mctx and various other global memory
contexts in various utilities and tests.
There is only a single network manager running on top of the loop
manager (except for tests). Refactor the network manager to be a
singleton (a single instance) and change the unit tests, so that the
shorter read timeouts apply only to a specific handle, not the whole
extra 'connect_nm' network manager instance.
All the applications built on top of the loop manager were required to
create just a single instance of the loop manager. Refactor the loop
manager to not expose this instance to the callers and keep the loop
manager object internal to the isc_loop compilation unit.
This significantly simplifies a number of data structures and calls to
the isc_loop API.
When send_done() is called with a ISC_R_CANCELED status (e.g. because
of a signal from ctrl+c), dig can fail to shutdown because
check_if_done() is not called in the branch. Add a check_if_done()
call.
When reusing a TCP connection (because of the '+keepopen' option),
dig detaches from the query after launching it. This can cause a
crash in dig in rare cases when the "receive" callback is called
earlier than the "send" callback.
The '_cancel_lookup()' function detaches a query only if it's
found in the 'lookup->q' list. Before this commit, with one
additional detach happening before recv_done() -> _cancel_lookup()
is called, it didn't cause problems because an earlier _query_detach()
was unlinking the query from 'lookup->q' (because it was the last
reference), so the additional detach and the skipped detach were
undoing each other.
That is unless the "receive" callback was called earlier than the
"send" callback, in which case the additional detach wasn't destroying
the query (and wasn't unlinking it from 'lookup->q') because the "send"
callback's attachment was still there, and so _cancel_lookup() was
trying to "steal" the "send" callback's attachment and causing an
assertion on 'INSIST(query->sendhandle == NULL);'.
Delete the detachment which caused the described situation.
Meson is a modern build system that has seen a rise in adoption and some
version of it is available in almost every platform supported.
Compared to automake, meson has the following advantages:
* Meson provides a significant boost to the build and configuration time
by better exploiting parallelism.
* Meson is subjectively considered to be better in readability.
These merits alone justify experimenting with meson as a way of
improving development time and ergonomics. However, there are some
compromises to ensure the transition goes relatively smooth:
* The system tests currently rely on various files within the source
directory. Changing this requirement is a non-trivial task that can't
be currently justified. Currently the last compiled build directory
writes into the source tree which is in turn used by pytest.
* The minimum version supported has been fixed at 0.61. Increasing this
value will require choosing a baseline of distributions that can
package with meson. On the contrary, there will likely be an attempt
to decrease this value to ensure almost universal support for building
BIND 9 with meson.
There were several methods how we used 'argv[0]'. Some programs had a
static value, some programs did use isc_file_progname(), some programs
stripped 'lt-' from the beginning of the name. And some used argv[0]
directly.
Unify the handling and all the variables into isc_commandline_progname
that gets populated by the new isc_commandline_init(argc, argv) call.
Instead of giving the memory context names with an explicit call to
isc_mem_setname(), add the name to isc_mem_create() call to have all the
memory contexts an unconditional name.
replace the pattern `for (result = dns_rdataset_first(x); result ==
ISC_R_SUCCES; result = dns_rdataset_next(x)` with a new
`DNS_RDATASET_FOREACH` macro throughout BIND.
previously, ISC_LIST_FOREACH and ISC_LIST_FOREACH_SAFE were
two separate macros, with the _SAFE version allowing entries
to be unlinked during the loop. ISC_LIST_FOREACH is now also
safe, and the separate _SAFE macro has been removed.
similarly, the ISC_LIST_FOREACH_REV macro is now safe, and
ISC_LIST_FOREACH_REV_SAFE has also been removed.
The offical EDNS option name for "UL" is "UPDATE-LEASE". We now
emit "UPDATE-LEASE" instead of "UL", when printing messages, but
"UL" has been retained as an alias on the command line.
Update leases consist of 1 or 2 values, LEASE and KEY-LEASE. These
components are now emitted separately so they can be easily extracted
from YAML output. Tests have been added to check YAML correctness.
use the ISC_LIST_FOREACH pattern in places where lists had
been iterated using a different pattern from the typical
`for` loop: for example, `while (!ISC_LIST_EMPTY(...))` or
`while ((e = ISC_LIST_HEAD(...)) != NULL)`.
the pattern `for (x = ISC_LIST_HEAD(...); x != NULL; ISC_LIST_NEXT(...)`
has been changed to `ISC_LIST_FOREACH` throughout BIND, except in a few
cases where the change would be excessively complex.
in most cases this was a straightforward change. in some places,
however, the list element variable was referenced after the loop
ended, and the code was refactored to avoid this necessity.
also, because `ISC_LIST_FOREACH` uses typeof(list.head) to declare
the list elements, compilation failures can occur if the list object
has a `const` qualifier. some `const` qualifiers have been removed
from function parameters to avoid this problem, and where that was not
possible, `UNCONST` was used.
ISC_LIST_FOREACH and related macros now use 'typeof(list.head)' to
declare the list elements automatically; the caller no longer needs
to do so.
ISC_LIST_FOREACH_SAFE also now implicitly declares its own 'next'
pointer, so it only needs three parameters instead of four.
In the code base it is very common to iterate over all names in a message
section and all rdatasets for each name, but various idioms are used for
iteration.
This commit standardizes them as much as possible to a single idiom,
using the macro MSG_SECTION_FOREACH, similar to the existing
ISC_LIST_FOREACH.
Add "+showbadvers" to display the BADVERS response similarly
to "+showbadcookie". Additionally reset the EDNS version to
the requested version in "dig +trace" so that EDNS version
negotiation can be tested at all levels of the trace rather
that just when requesting the root nameservers.
Since algorithm fetching is handled purely in libisc, FIPS mode toggling
can be purely done in within the library instead of provider fetching in
the binary for OpenSSL >=3.0.
Disabling FIPS mode isn't a realistic requirement and isn't done
anywhere in the codebase. Make the FIPS mode toggle enable-only to
reflect the situation.
previously, dns_name_fromtext() took both a target name and an
optional target buffer parameter, which could override the name's
dedicated buffer. this interface is unnecessarily complex.
we now have two functions, dns_name_fromtext() to convert text
into a dns_name that has a dedicated buffer, and dns_name_wirefromtext()
to convert text into uncompressed DNS wire format and append it to a
target buffer.
in cases where it really is necessary to have both, we can use
dns_name_fromtext() to load the dns_name, then dns_name_towire()
to append the wire format to the target buffer.
dns_name_fromtext() stores the converted name in the 'name'
passed to it, and optionally also copies it in wire format to
a buffer 'target'. this makes the interface unnecessarily
complex, and could be simplified by having a different function
for each purpose. as a first step, remove uses of the target
buffer in calls to dns_name_fromtext() where it wasn't actually
needed.
the target buffer passed to dns_name_concatenate() was never
used (except for one place in dig, where it wasn't actually
needed, and has already been removed in a prior commit).
we can safely remove the parameter.
