.. Copyright (C) Internet Systems Consortium, Inc. ("ISC") .. .. SPDX-License-Identifier: MPL-2.0 .. .. This Source Code Form is subject to the terms of the Mozilla Public .. License, v. 2.0. If a copy of the MPL was not distributed with this .. file, you can obtain one at https://mozilla.org/MPL/2.0/. .. .. See the COPYRIGHT file distributed with this work for additional .. information regarding copyright ownership. .. highlight: console .. iscman:: named-rrchecker .. program:: named-rrchecker .. _man_named-rrchecker: named-rrchecker - syntax checker for individual DNS resource records -------------------------------------------------------------------- Synopsis ~~~~~~~~ :program:`named-rrchecker` [**-h**] [**-o** origin] [**-p**] [**-u**] [**-C**] [**-T**] [**-P**] Description ~~~~~~~~~~~ :program:`named-rrchecker` reads a single DNS resource record (RR) from standard input and checks whether it is syntactically correct. The input format is a minimal subset of the DNS zone file format. The entire input must be: CLASS TYPE RDATA * Input must not start with an owner (domain) name * The `CLASS` field is mandatory (typically ``IN``). * The `TTL` field **must not** be present. * RDATA format is specific to each RRTYPE. * Leading and trailing whitespace in each field is ignored. Format details can be found in :rfc:`1035#section-5.1` under ```` specification. :rfc:`3597` format is also accepted in any of the input fields. See :ref:`Examples`. Options ~~~~~~~ .. option:: -o origin This option specifies the origin to be used when interpreting names in the record: it defaults to root (`.`). The specified origin is always taken as an absolute name. .. option:: -p This option prints out the resulting record in canonical form. If there is no canonical form defined, the record is printed in :rfc:`3597` unknown record format. .. option:: -u This option prints out the resulting record in :rfc:`3597` unknown record format. .. option:: -C, -T, -P These options do not read input. They print out known classes, standard types, and private type mnemonics. Each item is printed on a separate line. The resulting list of private types may be empty .. option:: -h This option prints out the help menu. .. _examples: Examples ~~~~~~~~ Pay close attention to the :manpage:`echo` command line options `-e` and `-n`, as they affect whitespace in the input to ``named-rrchecker``. echo -n 'IN A 192.0.2.1' | named-rrchecker * Valid input is in :rfc:`1035` format with no newline at the end of the input. * Return code 0. echo -e '\\n \\n IN\\tA 192.0.2.1 \\t \\n\\n ' | named-rrchecker -p * Valid input with leading and trailing whitespace. * Output: ``IN A 192.0.2.1`` * Leading and trailing whitespace is not part of the output. Relative names and origin ^^^^^^^^^^^^^^^^^^^^^^^^^ echo 'IN CNAME target' | named-rrchecker -p * Valid input with a relative name as the CNAME target. * Output: ``IN CNAME target.`` * Relative name `target` from the input is converted to an absolute name using the default origin ``.`` (root). echo 'IN CNAME target' | named-rrchecker -p -o origin.test * Valid input with a relative name as the CNAME target. * Output: ``IN CNAME target.origin.test.`` * Relative name `target` from the input is converted to an absolute name using the specified origin ``origin.test`` echo 'IN CNAME target.' | named-rrchecker -p -o origin.test * Valid input with an absolute name as the CNAME target. * Output: ``IN CNAME target.`` * The specified origin has no influence if `target` from the input is already absolute. Special characters ^^^^^^^^^^^^^^^^^^ Special characters allowed in zone files by :rfc:`1035#section-5.1` are accepted. echo 'IN CNAME t\\097r\\get\\.' | named-rrchecker -p -o origin.test * Valid input with backslash escapes. * Output: ``IN CNAME target\..origin.test.`` * ``\097`` denotes an ASCII value in decimal, which, in this example, is the character ``a``. * ``\g`` is converted to a plain ``g`` because the ``g`` character does not have a special meaning and so the ``\`` prefix does nothing in this case. * ``\.`` denotes a literal ASCII dot (here as a part of the CNAME target name). Special meaning of ``.`` as the DNS label separator was disabled by the preceding ``\`` prefix. echo 'IN CNAME @' | named-rrchecker -p -o origin.test * Valid input with ``@`` used as a reference to the specified origin. * Output: ``IN CNAME origin.test.`` echo 'IN CNAME \\@' | named-rrchecker -p -o origin.test * Valid input with a literal ``@`` character (escaped). * Output: ``IN CNAME \@.origin.test.`` echo 'IN CNAME prefix.@' | named-rrchecker -p -o origin.test * Valid input with ``@`` used as a reference to the specifed origin. * Output: ``IN CNAME prefix.\@.origin.test.`` * ``@`` has special meaning only if it is free-standing. echo 'IN A 192.0.2.1; comment' | named-rrchecker -p * Valid input with a trailing comment. Note the lack of whitespace before the start of the comment. * Output: ``IN A 192.0.2.1`` For multi-line examples see the next section. Multi-token records ^^^^^^^^^^^^^^^^^^^ echo -e 'IN TXT two words \\n' | named-rrchecker -p * Valid TXT RR with two unquoted words and trailing whitespace. * Output: ``IN TXT "two" "words"`` * Two unquoted words in the input are treated as two ``\ s per :rfc:`1035#section-3.3.14`. * Trailing whitespace is omitted from the last ``. echo -e 'IN TXT "two words" \\n' | named-rrchecker -p * Valid TXT RR with one `character-string` and trailing whitespace. * Output: ``IN TXT "two words"`` echo -e 'IN TXT "problematic newline\\n"' | named-rrchecker -p * Invalid input - the closing ``"`` is not detected before the end of the line. echo 'IN TXT "with newline\\010"' | named-rrchecker -p * Valid input with an escaped newline character inside `character-string`. * Output: ``IN TXT "with newline\010"`` echo -e 'IN TXT ( two\\nwords )' | named-rrchecker -p * Valid multi-line input with line continuation allowed inside optional parentheses in the RDATA field. * Output: ``IN TXT "two" "words"`` echo -e 'IN TXT ( two\\nwords ; misplaced comment )' | named-rrchecker -p * Invalid input - comments, starting with ";", are ignored by the parser, so the closing parenthesis should be before the semicolon. echo -e 'IN TXT ( two\\nwords ; a working comment\\n )' | named-rrchecker -p * Valid input - the comment is terminated with a newline. * Output: ``IN TXT "two" "words"`` echo 'IN HTTPS 1 . alpn="h2,h3"' | named-rrchecker -p * Valid HTTPS record * Output: ``IN HTTPS 1 . alpn="h2,h3"`` echo -e 'IN HTTPS ( 1 \\n . \\n alpn="dot")port=853' | named-rrchecker -p * Valid HTTPS record with individual sub-fields split across multiple lines using :rfc:`1035#section-5.1` parentheses syntax to group data that crosses a line boundary. * Note the missing whitespace between the closing parenthesis and adjacent tokens. * Output: ``IN HTTPS 1 . alpn="dot" port=853`` Unknown type handling ^^^^^^^^^^^^^^^^^^^^^ echo 'IN A 192.0.2.1' | named-rrchecker -u * Valid input in :rfc:`1035` format. * Output in :rfc:`3957` format: ``CLASS1 TYPE1 \# 4 C0000201`` echo 'CLASS1 TYPE1 \\# 4 C0000201' | named-rrchecker -p * Valid input in :rfc:`3597` format. * Output in :rfc:`1035` format: ``IN A 192.0.2.1`` echo 'IN A \\# 4 C0000201' | named-rrchecker -p * Valid input with class and type in :rfc:`1035` format and rdata in :rfc:`3597` format. * Output in :rfc:`1035` format: ``IN A 192.0.2.1`` echo 'IN HTTPS 1 . key3=\\001\\000' | named-rrchecker -p * Valid input with :rfc:`9460` syntax for an unknown `key3` field. Syntax ``\001\000`` produces two octets with values 1 and 0, respectively. * Output: ``IN HTTPS 1 . port=256`` * `key3` matches the standardized key name `port`. * Octets 1 and 0 were decoded as integer values in big-endian encoding. echo 'IN HTTPS 1 . key3=\\001' | named-rrchecker -p * Invalid input - the length of the value for `key3` (i.e. port) does not match the known standard format for that parameter in the SVCB RRTYPE. echo 'IN HTTPS 1 . port=\\001\\000' | named-rrchecker -p * Invalid input - the key `port`, when specified using its standard mnemonic name, **must** use standard key-specific syntax. Meta values ^^^^^^^^^^^ echo 'IN AXFR' | named-rrchecker * Invalid input - AXFR is a meta type, not a genuine RRTYPE. echo 'ANY A 192.0.2.1' | named-rrchecker * Invalid input - ANY is meta class, not a true class. echo 'A 192.0.2.1' | named-rrchecker * Invalid input - the class field is missing, so the parser would try and fail to interpret the RRTYPE A as the class. Return Codes ~~~~~~~~~~~~ 0 The whole input was parsed as one syntactically valid resource record. 1 The input is not a syntactically valid resource record, or the given type is not supported, or either/both class and type are meta-values, which should not appear in zone files. See Also ~~~~~~~~ :rfc:`1034`, :rfc:`1035`, :rfc:`3957`, :iscman:`named(8) `.