Age | Commit message (Collapse) | Author |
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Let's make sure the root domain is normalized to ".", rather than then empty string, so that there's actually something
to see on screen. Normally, we don't append a trailing dot to normalized domain names, but do so in the one exception
of the root domain, taking inspiration from UNIX file system paths.
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Move IDNA logic out of the normal domain name processing, and into the bus frontend calls. Previously whenever
comparing two domain names we'd implicitly do IDNA conversion so that "pöttering.de" and "xn--pttering-n4a.de" would be
considered equal. This is problematic not only for DNSSEC, but actually also against he IDNA specs.
Moreover it creates problems when encoding DNS-SD services in classic DNS. There, the specification suggests using
UTF8 encoding for the actual service name, but apply IDNA encoding to the domain suffix.
With this change IDNA conversion is done only:
- When the user passes a non-ASCII hostname when resolving a host name using ResolveHostname()
- When the user passes a non-ASCII domain suffix when resolving a service using ResolveService()
No IDNA encoding is done anymore:
- When the user does raw ResolveRecord() RR resolving
- On the service part of a DNS-SD service name
Previously, IDNA encoding was done when serializing names into packets, at a point where information whether something
is a label that needs IDNA encoding or not was not available, but at a point whether it was known whether to generate a
classic DNS packet (where IDNA applies), or an mDNS/LLMNR packet (where IDNA does not apply, and UTF8 is used instead
for all host names). With this change each DnsQuery object will now maintain two copies of the DnsQuestion to ask: one
encoded in IDNA for use with classic DNS, and one encoded in UTF8 for use with LLMNR and MulticastDNS.
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equivalent
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empty non-terminals generally lack NSEC RRs, which means we can deduce their existance only from the fact that there
are other RRs that contain them in their suffix. Specifically, the NSEC proof for NODATA on ENTs works by sending the
NSEC whose next name is a suffix of the queried name to the client. Use this information properly.
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source and zone in each RR
Having this information available is useful when we need to check whether various RRs are suitable for proofs. This
information is stored in the RRs as number of labels to skip from the beginning of the owner name to reach the
synthesizing source/signer. Simple accessor calls are then added to retrieve the signer/source from the RR using this
information.
This also moves validation of a a number of RRSIG parameters into a new call dnssec_rrsig_prepare() that as side-effect
initializes the two numeric values.
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We frequently unescape DNS label follwed by IDNA undoing. We now have a function that does that in one step, hence use
it everywhere.
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This way we become compatible with DNS names with embedded NUL bytes.
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skip first label
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ascii_strcasecmp_n()
This makes our code compatible with embedded NUL bytes, as we don't care about NUL bytes anymore.
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dns_name_startswith() is to dns_name_endswith() as startswith() is to endswith().
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This also introduces a new macro siphash24_compress_byte() which is useful to add a single byte into the hash stream,
and ports one user over to it.
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in labels
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Previously, we'd not allow control characters to be embedded in domain
names, even when escaped. Since cloudflare uses \000 however to
implement its synthethic minimally covering NSEC RRs, we should allow
them, as long as they are properly escaped.
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All our other domain name handling functions make no destinction between
domain names that end in a dot plus a NUL, or those just ending in a
NUL. Make sure dns_name_compare_func() and dns_label_unescape_suffix()
do the same.
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Be stricter when searching suitable NSEC3 RRs for proof: generalize the
check we use to find suitable NSEC3 RRs, in nsec3_is_good(), and add
additional checks, such as checking whether all NSEC3 RRs use the same
parameters, have the same suffix and so on.
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Note that this is still not complete, one additional step is still
missing: when we verified that a wildcard RRset is properly signed, we
still need to do an NSEC/NSEC3 proof that no more specific RRset exists.
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The next step of a general cleanup of our includes. This one mostly
adds missing includes but there are a few removals as well.
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canonical names
We'll need this later when putting together RR serializations to
checksum.
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Some calls used ENOBUFS to indicate too-short result buffers, others
used ENOSPC. Let's unify this on ENOBUFS.
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Let's better be safe than sorry.
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domain
The root domain consists of zero labels, and we should be able to encode
that.
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Make sure dns_name_normalize(), dns_name_concat(), dns_name_is_valid()
do not accept/generate invalidly long hostnames, i.e. longer than 253
characters.
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Labels of zero length are not OK, refuse them early on. The concept of a
"zero-length label" doesn't exist, a zero-length full domain name
however does (representing the root domain). See RFC 2181, Section 11.
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The new dns_label_escape() call now operates on a buffer passed in,
similar to dns_label_unescape(). This should make decoding a bit faster,
and nicer.
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For similar reasons as dns_name_is_root() got changed in the previous
commit.
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Let's change the return value to bool. If we encounter an error while
parsing, return "false" instead of the actual parsing error, after all
the specified hostname does not qualify for what the function is
supposed to test.
Dealing with the additional error codes was always cumbersome, and
easily misused, like for example in the DHCP code.
Let's also rename the functions from dns_name_root() to
dns_name_is_root(), to indicate that this function checks something and
returns a bool. Similar for dns_name_is_signal_label().
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Most servers apparently always implicitly convert DNAME to CNAME, but
some servers don't, hence implement this properly, as this is required
by edns0.
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This adds dns_service_join() and dns_service_split() which may be used
to concatenate a DNS-SD service name, am SRV service type string, and a
domain name into a full resolvable DNS domain name string. If the
service name is specified as NULL, only the type and domain are
appended, to implement classic, non-DNS-SD SRV lookups.
The reverse is dns_service_split() which takes the full name, and split
it into the three components again.
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The function converts a domain name string to the wire format
described in RFC 1035 Section 3.1.
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string-util.[ch]
There are more than enough calls doing string manipulations to deserve
its own files, hence do something about it.
This patch also sorts the #include blocks of all files that needed to be
updated, according to the sorting suggestions from CODING_STYLE. Since
pretty much every file needs our string manipulation functions this
effectively means that most files have sorted #include blocks now.
Also touches a few unrelated include files.
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Make sure all variable-length inputs are properly terminated or that
their length is encoded in some way. This avoids ambiguity of
adjacent inputs.
E.g., in case of a hash function taking two strings, compressing "ab"
followed by "c" is now distinct from "a" followed by "bc".
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All our hash functions are based on siphash24(), factor out
siphash_init() and siphash24_finalize() and pass the siphash
state to the hash functions rather than the hash key.
This simplifies the hash functions, and in particular makes
composition simpler as calling siphash24_compress() repeatedly
on separate chunks of input has the same effect as first
concatenating the input and then calling siphash23_compress()
on the result.
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This is specifically useful for appending the mDNS ".local" suffix to a
single-label hostname in the most correct way. (used in later commit)
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Given three DNS names this function indicates if the second argument lies
strictly between the first and the third according to the canonical DNS
name order. Note that the order is circular, so the last name is
considered to be before the first.
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The canonical DNS name ordering considers the rightmost label the most significant,
we were considering it the least significant. This is important when implementing
NSEC, which relies on the correct order.
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Intended to be called repeatedly, and returns then successive unescaped labels
from the most to the least significant (left to right).
This is slightly inefficient as it scans the string three times (two would be
sufficient): once to find the end of the string, once to find the beginning
of each label and lastly once to do the actual unescaping. The latter two
could be done in one go, but that seemed unnecessarily convoluted.
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