Make sure ai_canonname is set when AI_CANONNAME was requested.

We document, and posix requires, to return a NUL-terminated string on
a successful call to getaddrinfo(3) when AI_CANONNAME was set.

Make sure ai_canonname is set when AI_CANONNAME was requested.

We document, and posix requires, to return a NUL-terminated string on
a successful call to getaddrinfo(3) when AI_CANONNAME was set.

If the canonical name cannot be determined, return the node name as
suggested by posix.

OK guenther

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Make sure to return a proper string in ai_canonname.

When we made sure that getaddrinfo(3) always resolves "localhost" to
the loopback address we forgot to set ai_canonname if AI_CANONNAME or
AI_FQD

Make sure to return a proper string in ai_canonname.

When we made sure that getaddrinfo(3) always resolves "localhost" to
the loopback address we forgot to set ai_canonname if AI_CANONNAME or
AI_FQDN is set. On a successful call ai_canonname has to be a NUL-terminated
string if either of those flags are set.

Problem observed by a@alexis-fouilhe.fr in smtpd(8) with a hostname of
"localhost".

OK millert

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Do not short-circuit localhost resolution when AI_NUMERICHOST is set.

localhost is not a valid IP address and so getaddrinfo(3) has to fail.
Found by anton in pfctl & ipsecctl regress.

OK anton

localhost is either 127.0.0.1 or ::1, nothing else.

RFC 6761, 6.3 Domain Name Reservation Considerations for "localhost.":
3. Name resolution APIs and libraries SHOULD recognize localhost

localhost is either 127.0.0.1 or ::1, nothing else.

RFC 6761, 6.3 Domain Name Reservation Considerations for "localhost.":
3. Name resolution APIs and libraries SHOULD recognize localhost
names as special and SHOULD always return the IP loopback address
for address queries and negative responses for all other query
types. Name resolution APIs SHOULD NOT send queries for
localhost names to their configured caching DNS server(s).

This makes sure that the getaddrinfo(3) and gethostbyname(3) family of
functions always return the loopback address and do not send queries
to name servers. This includes "localhost", "localhost." and
everything under ".localhost" and ".localhost.".

For example, a host underneath the .com.ar zone will per default have
a search list of "com.ar.". resolv.conf(5) has a default of "lookup
bind file". Both combined will result in lookups for "localhost" to
not return 127.0.0.1 because localhost.com.ar is registered in DNS.

It has been known for decades that this is a problem, especially for
localhost.

Problem recently spotted by gonzalo@ and debugged by sthen@

Testing sthen, gonzalo
Input & OK phessler, eric, millert
OK sthen, kn, deraadt

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spelling fixes; from paul tagliamonte
any changes not taken noted on tech, but chiefly here i did not take the
cancelation - cancellation changes;

Restrict what getaddrinfo(3) is willing to try to resolve.

Programs assume that a successful call to getaddrinfo(3) validates the
input as "safe", but that's not true. Characters like '$', '`', '\n'

Restrict what getaddrinfo(3) is willing to try to resolve.

Programs assume that a successful call to getaddrinfo(3) validates the
input as "safe", but that's not true. Characters like '$', '`', '\n'
or '*' can traverse the DNS without problems, but have special
meaning, for example a shell.

There is a function res_hnok() already in libc, but it validates if a
string is a host name, which is too strict in practice. For example
foo-.example.com is not a valid host name, but is used on the
Internet.

Posix has this to say:
"The getaddrinfo() function shall translate the name of a service
location (for example, a host name)"

It hints that the input should be a host name, but it does not
restrict it to it.

This introduces a function hnok_lenient() which restricts the input to
getaddrinfo(3) to the set [A-z0-9-_.]. Additionally two consecutive
dots ('.') are not allowed nor can the string start with - or '.'.

glibc introduced a similar restriction years ago, so this should not
cause problems.

It has been known in the DNS community for years, probably decades
that getaddrinfo(3) is too lenient what it accepts, but it has always
been kicked down the road as "not a DNS problem". Unfortunately this
information never made it out of the DNS community and no coordinated
effort happened to have this addressed in operating systems.

David Leadbeater recently demonstrated how ssh(1) and ftp(1) are too
trusting with what getaddrinfo(3) accepts. Both have been fixed
independently of this.

Input deraadt, eric
OK millert, deraadt

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When checking for available address family for AI_ADDRCONFIG consider
the routing domain we are currently in. Otherwise we might end up with
address families that are not available in the current rdo

When checking for available address family for AI_ADDRCONFIG consider
the routing domain we are currently in. Otherwise we might end up with
address families that are not available in the current rdomain but in
others since getifaddrs(3) gives us all interface addresses in the
system.
Clue-bat & OK claudio, input & OK eric, OK kn

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For correctness, do not read struct servent if getservbyname_r() failed.
Also simplify code.

More "explicitely" -> "explicitly" in various comments.

ok guenther@ tb@ deraadt@

Put a common flags field in the query struct, rather than in some
elements of the union.

This field is for internal asr flags. The flags in "struct rrset" and
"struct ni" are different kinds of fla

Put a common flags field in the query struct, rather than in some
elements of the union.

This field is for internal asr flags. The flags in "struct rrset" and
"struct ni" are different kinds of flags.

ok eric@

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Put a common subq pointer in the query struct, rather than one in each
element of the union.

ok gilles@ millert@ krw@

missing breaks

ok jca@ krw@ gilles@

Report the errno set by getifaddrs(3) if the setup for AI_ADDRCONFIG fails,
rather than a non-informative EAI_FAIL. Compare to -1 for error detection
while here.

ok jca@ gilles@

Remove support for HOSTALIASES from the resolver. This "open and parse
any file indicated by an environment variable" feature inside the
resolver is incompatible with what pledge "dns" is trying to

Remove support for HOSTALIASES from the resolver. This "open and parse
any file indicated by an environment variable" feature inside the
resolver is incompatible with what pledge "dns" is trying to be. It is
a misguided "feature" added way back in history which almost noone uses,
but everyone has to assume the risk from.
ok eric florian kettenis

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Remove support for "lookup yp" in /etc/resolv.conf. This historical
wart is incompatible with pledge, because suddenly a "dns" operation
needs "getpw" access to ypbind/ypserv, etc. file + dns acces

Remove support for "lookup yp" in /etc/resolv.conf. This historical
wart is incompatible with pledge, because suddenly a "dns" operation
needs "getpw" access to ypbind/ypserv, etc. file + dns access is
enough for everyone, sorry if you were using that old SunOS 4.x style
mechanism, but it is now gone.
ok semarie millert florian

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fix conditionals

ok deraadt@

Handle case where no hint is passed in. Found as a crash of fdm by jturner@

getaddrinfo_async() shouldn't unconditionally intialize the resolver
via _asr_use_resolver(). If the hint specifies for AI_NUMERICHOST,
create a transient lookup context which won't try to open /etc

getaddrinfo_async() shouldn't unconditionally intialize the resolver
via _asr_use_resolver(). If the hint specifies for AI_NUMERICHOST,
create a transient lookup context which won't try to open /etc/reslov.conf
ok eric guenther

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remove bogus includes of err.h

remove unused static function

Wrap <asr.h> so internal calls go direct and all the symbols are weak

Hide all unnecessary asr / resolver related API with _ prefixes.
direction & ok guenther

Fix test against INADDR_LOOPBACK

ok gilles@

fix a possible off-by-one when reading /etc/hosts if it doesn't end
with a newline.

ok jca@

simply use _PATH_HOSTS where appropriate