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3934 Commits

Author SHA1 Message Date
Heikki Linnakangas
d981074c24 Misc SCRAM code cleanups.
* Move computation of SaltedPassword to a separate function from
  scram_ClientOrServerKey(). This saves a lot of cycles in libpq, by
  computing SaltedPassword only once per authentication. (Computing
  SaltedPassword is expensive by design.)

* Split scram_ClientOrServerKey() into two functions. Improves
  readability, by making the calling code less verbose.

* Rename "server proof" to "server signature", to better match the
  nomenclature used in RFC 5802.

* Rename SCRAM_SALT_LEN to SCRAM_DEFAULT_SALT_LEN, to make it more clear
  that the salt can be of any length, and the constant only specifies how
  long a salt we use when we generate a new verifier. Also rename
  SCRAM_ITERATIONS_DEFAULT to SCRAM_DEFAULT_ITERATIONS, for consistency.

These things caught my eye while working on other upcoming changes.
2017-04-28 15:22:38 +03:00
Andres Freund
b182a4ae2f Don't include sys/poll.h anymore.
poll.h is mandated by Single Unix Spec v2, the usual baseline for
postgres on unix.  None of the unixoid buildfarms animals has
sys/poll.h but not poll.h.  Therefore there's not much point to test
for sys/poll.h's existence and include it optionally.

Author: Andres Freund, per suggestion from Tom Lane
Discussion: https://postgr.es/m/20505.1492723662@sss.pgh.pa.us
2017-04-23 16:11:35 -07:00
Tom Lane
5041cdf2b7 Partially revert commit 536d47bd9d.
Per buildfarm, the "#ifdef F_SETFD" removed in that commit actually
is needed on Windows, because fcntl() isn't available at all on that
platform, unless using Cygwin.  We could perhaps spell it more like
"#ifdef HAVE_FCNTL", or "#ifndef WIN32", but it's not clear that
those choices are better.

It does seem that we don't need the bogus manual definition of
FD_CLOEXEC, though, so keep that change.

Discussion: https://postgr.es/m/26254.1492805635@sss.pgh.pa.us
2017-04-22 02:06:16 -04:00
Tom Lane
536d47bd9d Remove long-obsolete catering for platforms without F_SETFD/FD_CLOEXEC.
SUSv2 mandates that <fcntl.h> provide both F_SETFD and FD_CLOEXEC,
so it seems pretty unlikely that any platforms remain without those.
Remove the #ifdef-ery installed by commit 7627b91cd to see if the
buildfarm agrees.

Discussion: https://postgr.es/m/21444.1492798101@sss.pgh.pa.us
2017-04-21 14:48:29 -04:00
Tom Lane
77c316be7e Add missing erand48.c to libpq/.gitignore.
Oversight in commit 818fd4a67.  While at it, sync order of file list
in .gitignore with those in the Makefile.
2017-04-20 16:31:28 -04:00
Peter Eisentraut
674677c705 Remove trailing spaces in some output
Author: Alexander Law <exclusion@gmail.com>
2017-04-13 23:15:52 -04:00
Heikki Linnakangas
4f3b87ab78 Improve the SASL authentication protocol.
This contains some protocol changes to SASL authentiation (which is new
in v10):

* For future-proofing, in the AuthenticationSASL message that begins SASL
  authentication, provide a list of SASL mechanisms that the server
  supports, for the client to choose from. Currently, it's always just
  SCRAM-SHA-256.

* Add a separate authentication message type for the final server->client
  SASL message, which the client doesn't need to respond to. This makes
  it unambiguous whether the client is supposed to send a response or not.
  The SASL mechanism should know that anyway, but better to be explicit.

Also, in the server, support clients that don't send an Initial Client
response in the first SASLInitialResponse message. The server is supposed
to first send an empty request in that case, to which the client will
respond with the data that usually comes in the Initial Client Response.
libpq uses the Initial Client Response field and doesn't need this, and I
would assume any other sensible implementation to use Initial Client
Response, too, but let's follow the SASL spec.

Improve the documentation on SASL authentication in protocol. Add a
section describing the SASL message flow, and some details on our
SCRAM-SHA-256 implementation.

Document the different kinds of PasswordMessages that the frontend sends
in different phases of SASL authentication, as well as GSS/SSPI
authentication as separate message formats. Even though they're all 'p'
messages, and the exact format depends on the context, describing them as
separate message formats makes the documentation more clear.

Reviewed by Michael Paquier and Álvaro Hernández Tortosa.

Discussion: https://www.postgresql.org/message-id/CAB7nPqS-aFg0iM3AQOJwKDv_0WkAedRjs1W2X8EixSz+sKBXCQ@mail.gmail.com
2017-04-13 19:34:16 +03:00
Heikki Linnakangas
61bf96cab0 Refactor libpq authentication request processing.
Move the responsibility of reading the data from the authentication request
message from PQconnectPoll() to pg_fe_sendauth(). This way, PQconnectPoll()
doesn't need to know about all the different authentication request types,
and we don't need the extra fields in the pg_conn struct to pass the data
from PQconnectPoll() to pg_fe_sendauth() anymore.

Reviewed by Michael Paquier.

Discussion: https://www.postgresql.org/message-id/6490b975-5ee1-6280-ac1d-af975b19fb9a%40iki.fi
2017-04-13 19:34:14 +03:00
Magnus Hagander
a4777f3556 Remove symbol WIN32_ONLY_COMPILER
This used to mean "Visual C++ except in those parts where Borland C++
was supported where it meant one of those". Now that we don't support
Borland C++ anymore, simplify by using _MSC_VER which is the normal way
to detect Visual C++.
2017-04-11 15:22:21 +02:00
Magnus Hagander
6da56f3f84 Remove support for bcc and msvc standalone libpq builds
This removes the support for building just libpq using Borland C++ or
Visual C++. This has not worked properly for years, and given the number
of complaints it's clearly not worth the maintenance burden.

Building libpq using the standard MSVC build system is of course still
supported, along with mingw.
2017-04-11 15:22:21 +02:00
Tom Lane
aba696d1af Add newly-symlinked files to "make clean" target.
Oversight in 60f11b87a.
2017-04-08 14:25:45 -04:00
Heikki Linnakangas
60f11b87a2 Use SASLprep to normalize passwords for SCRAM authentication.
An important step of SASLprep normalization, is to convert the string to
Unicode normalization form NFKC. Unicode normalization requires a fairly
large table of character decompositions, which is generated from data
published by the Unicode consortium. The script to generate the table is
put in src/common/unicode, as well test code for the normalization.
A pre-generated version of the tables is included in src/include/common,
so you don't need the code in src/common/unicode to build PostgreSQL, only
if you wish to modify the normalization tables.

The SASLprep implementation depends on the UTF-8 functions from
src/backend/utils/mb/wchar.c. So to use it, you must also compile and link
that. That doesn't change anything for the current users of these
functions, the backend and libpq, as they both already link with wchar.o.
It would be good to move those functions into a separate file in
src/commmon, but I'll leave that for another day.

No documentation changes included, because there is no details on the
SCRAM mechanism in the docs anyway. An overview on that in the protocol
specification would probably be good, even though SCRAM is documented in
detail in RFC5802. I'll write that as a separate patch. An important thing
to mention there is that we apply SASLprep even on invalid UTF-8 strings,
to support other encodings.

Patch by Michael Paquier and me.

Discussion: https://www.postgresql.org/message-id/CAB7nPqSByyEmAVLtEf1KxTRh=PWNKiWKEKQR=e1yGehz=wbymQ@mail.gmail.com
2017-04-07 14:56:05 +03:00
Heikki Linnakangas
07044efe00 Remove bogus SCRAM_ITERATION_LEN constant.
It was not used for what the comment claimed, at all. It was actually used
as the 'base' argument to strtol(), when reading the iteration count. We
don't need a constant for base-10, so remove it.
2017-04-06 17:41:48 +03:00
Magnus Hagander
156d3882f8 Fix typo in comment
Daniel Gustafsson
2017-03-31 09:00:38 +02:00
Peter Eisentraut
facde2a98f Clean up Perl code according to perlcritic
Fix all perlcritic warnings of severity level 5, except in
src/backend/utils/Gen_dummy_probes.pl, which is automatically generated.

Reviewed-by: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
2017-03-27 08:18:22 -04:00
Tom Lane
59bfb190f7 Add missed "make clean" logic in src/interfaces/libpq/Makefile.
Commit 818fd4a67 missed cleaning up the symlinks it added for various .c
files imported from src/port and src/common.  Neatnik-ishly make the
file lists in the "clean" target look exactly like the earlier lists of
what to symlink in.
2017-03-20 12:51:45 -04:00
Michael Meskes
928250aef5 Fix schedule of ecpg test files to only try two-phase commit test when possible. 2017-03-18 10:35:14 +01:00
Peter Eisentraut
100871c2d1 ecpg: Improve some variable names
based on patch from Josh Soref <jsoref@gmail.com>
2017-03-14 12:58:39 -04:00
Peter Eisentraut
a47b38c9ee Spelling fixes
From: Josh Soref <jsoref@gmail.com>
2017-03-14 12:58:39 -04:00
Peter Eisentraut
f97a028d8e Spelling fixes in code comments
From: Josh Soref <jsoref@gmail.com>
2017-03-14 12:58:39 -04:00
Robert Haas
c6c099d31a Update .gitignore
Commit 42fcad68a9 failed to do this.

Michael Paquier

Discussion: http://postgr.es/m/CAB7nPqTXK9Qn8TmonPf29jNXGw_CA3fTDaRfgnbHCFYr-Tx6qw@mail.gmail.com
2017-03-14 12:17:44 -04:00
Michael Meskes
42fcad68a9 Add test case for two phase commit. Also by Masahiko Sawada. 2017-03-13 21:03:55 +01:00
Michael Meskes
43c79c7d68 Ecpg should support COMMIT PREPARED and ROLLBACK PREPARED.
The problem was that "begin transaction" was issued automatically
before executing COMMIT/ROLLBACK PREPARED if not in auto commit. This fix by
Masahiko Sawada fixes this.
2017-03-13 21:03:55 +01:00
Michael Meskes
d1ca82d0a2 Fix a potential double-free in ecpg. 2017-03-10 10:32:41 +01:00
Tom Lane
9722bb5757 Fix inclusions of postgres_fe.h from .h files.
We have a project policy that every .c file should start by including
postgres.h, postgres_fe.h, or c.h as appropriate; and then there is no
need for any .h file to explicitly include any of these.  Fix a few
headers that were violating this policy by including postgres_fe.h.

Discussion: https://postgr.es/m/CAEepm=2zCoeq3QxVwhS5DFeUh=yU6z81pbWMgfOB8OzyiBwxzw@mail.gmail.com
Discussion: https://postgr.es/m/11634.1488932128@sss.pgh.pa.us
2017-03-08 20:41:06 -05:00
Heikki Linnakangas
95c1dbcdff A collection of small fixes for the SCRAM patch.
* Add required #includes for htonl. Per buildfarm members pademelon/gaur.

* Remove unnecessary "#include <utils/memutils>".

* Fix checking for empty string in pg_SASL_init. (Reported by Peter
  Eisentraut and his compiler)

* Move code in pg_SASL_init to match the recent changes (commit ba005f193d)
  to pg_fe_sendauth() function, where it's copied from.

* Return value of malloc() was not checked for NULL in
  scram_SaltedPassword(). Fix by avoiding the malloc().
2017-03-07 19:00:22 +02:00
Heikki Linnakangas
55acfcbffd Fix comments in SCRAM-SHA-256 patch.
Amit Kapila.
2017-03-07 15:24:27 +02:00
Heikki Linnakangas
818fd4a67d Support SCRAM-SHA-256 authentication (RFC 5802 and 7677).
This introduces a new generic SASL authentication method, similar to the
GSS and SSPI methods. The server first tells the client which SASL
authentication mechanism to use, and then the mechanism-specific SASL
messages are exchanged in AuthenticationSASLcontinue and PasswordMessage
messages. Only SCRAM-SHA-256 is supported at the moment, but this allows
adding more SASL mechanisms in the future, without changing the overall
protocol.

Support for channel binding, aka SCRAM-SHA-256-PLUS is left for later.

The SASLPrep algorithm, for pre-processing the password, is not yet
implemented. That could cause trouble, if you use a password with
non-ASCII characters, and a client library that does implement SASLprep.
That will hopefully be added later.

Authorization identities, as specified in the SCRAM-SHA-256 specification,
are ignored. SET SESSION AUTHORIZATION provides more or less the same
functionality, anyway.

If a user doesn't exist, perform a "mock" authentication, by constructing
an authentic-looking challenge on the fly. The challenge is derived from
a new system-wide random value, "mock authentication nonce", which is
created at initdb, and stored in the control file. We go through these
motions, in order to not give away the information on whether the user
exists, to unauthenticated users.

Bumps PG_CONTROL_VERSION, because of the new field in control file.

Patch by Michael Paquier and Heikki Linnakangas, reviewed at different
stages by Robert Haas, Stephen Frost, David Steele, Aleksander Alekseev,
and many others.

Discussion: https://www.postgresql.org/message-id/CAB7nPqRbR3GmFYdedCAhzukfKrgBLTLtMvENOmPrVWREsZkF8g%40mail.gmail.com
Discussion: https://www.postgresql.org/message-id/CAB7nPqSMXU35g%3DW9X74HVeQp0uvgJxvYOuA4A-A3M%2B0wfEBv-w%40mail.gmail.com
Discussion: https://www.postgresql.org/message-id/55192AFE.6080106@iki.fi
2017-03-07 14:25:40 +02:00
Tom Lane
9e3755ecb2 Remove useless duplicate inclusions of system header files.
c.h #includes a number of core libc header files, such as <stdio.h>.
There's no point in re-including these after having read postgres.h,
postgres_fe.h, or c.h; so remove code that did so.

While at it, also fix some places that were ignoring our standard pattern
of "include postgres[_fe].h, then system header files, then other Postgres
header files".  While there's not any great magic in doing it that way
rather than system headers last, it's silly to have just a few files
deviating from the general pattern.  (But I didn't attempt to enforce this
globally, only in files I was touching anyway.)

I'd be the first to say that this is mostly compulsive neatnik-ism,
but over time it might save enough compile cycles to be useful.
2017-02-25 16:12:55 -05:00
Tom Lane
c5658a0764 Suppress compiler warnings in ecpg test on newer Windows toolchains.
nan_test.pgc supposed that it could unconditionally #define isnan()
and isinf() on WIN32.  This was evidently copied at some point from
src/include/port/win32.h, but nowadays there's a test on _MSC_VER
there.  Make nan_test.pgc look the same.

Per buildfarm warnings.  There's no evidence this produces anything
worse than a warning, and besides it's only a test case, so I don't
feel a need to back-patch.
2017-02-24 16:45:32 -05:00
Tom Lane
b9d092c962 Remove now-dead code for !HAVE_INT64_TIMESTAMP.
This is a basically mechanical removal of #ifdef HAVE_INT64_TIMESTAMP
tests and the negative-case controlled code.

Discussion: https://postgr.es/m/26788.1487455319@sss.pgh.pa.us
2017-02-23 14:04:43 -05:00
Tom Lane
b6aa17e0ae De-support floating-point timestamps.
Per discussion, the time has come to do this.  The handwriting has been
on the wall at least since 9.0 that this would happen someday, whenever
it got to be too much of a burden to support the float-timestamp option.
The triggering factor now is the discovery that there are multiple bugs
in the code that attempts to implement use of integer timestamps in the
replication protocol even when the server is built for float timestamps.
The internal float timestamps leak into the protocol fields in places.
While we could fix the identified bugs, there's a very high risk of
introducing more.  Trying to build a wall that would positively prevent
mixing integer and float timestamps is more complexity than we want to
undertake to maintain a long-deprecated option.  The fact that these
bugs weren't found through testing also indicates a lack of interest
in float timestamps.

This commit disables configure's --disable-integer-datetimes switch
(it'll still accept --enable-integer-datetimes, though), removes direct
references to USE_INTEGER_DATETIMES, and removes discussion of float
timestamps from the user documentation.  A considerable amount of code is
rendered dead by this, but removing that will occur as separate mop-up.

Discussion: https://postgr.es/m/26788.1487455319@sss.pgh.pa.us
2017-02-23 11:40:20 -05:00
Tom Lane
090f21bbad Make src/interfaces/libpq/test clean up after itself.
It failed to remove a .o file during "make clean", and it lacked
a .gitignore file entirely.
2017-02-19 17:18:10 -05:00
Robert Haas
1de0a4e00e libpq: Make target_session_attrs=read-write consume empty result.
Otherwise, the leftover empty result can cause problems in some
situations.

Michael Paquier and Ashutosh Bapat, per a report from Higuchi Daisuke
2017-02-15 11:05:44 -05:00
Robert Haas
8569955ee3 Fix typo in comment.
Higuchi Daisuke
2017-02-14 21:08:10 -05:00
Heikki Linnakangas
181bdb90ba Fix typos in comments.
Backpatch to all supported versions, where applicable, to make backpatching
of future fixes go more smoothly.

Josh Soref

Discussion: https://www.postgresql.org/message-id/CACZqfqCf+5qRztLPgmmosr-B0Ye4srWzzw_mo4c_8_B_mtjmJQ@mail.gmail.com
2017-02-06 11:33:58 +02:00
Tom Lane
8ac0365c22 Avoid improbable null pointer dereference in pgpassfileWarning().
Coverity complained that we might pass a null pointer to strcmp()
if PQresultErrorField were to return NULL.  That shouldn't be possible,
since the server is supposed to always provide some SQLSTATE or other
in an error message.  But we usually defend against such hazards, and
it only takes a little more code to do so here.

There's no good reason to think this is a live bug, so no back-patch.
2017-02-02 19:49:15 -05:00
Tom Lane
ba005f193d Allow password file name to be specified as a libpq connection parameter.
Formerly an alternate password file could only be selected via the
environment variable PGPASSFILE; now it can also be selected via a
new connection parameter "passfile", corresponding to the conventions
for most other connection parameters.  There was some concern about
this creating a security weakness, but it was agreed that that argument
was pretty thin, and there are clear use-cases for handling password
files this way.

Julian Markwort, reviewed by Fabien Coelho, some adjustments by me

Discussion: https://postgr.es/m/a4b4f4f1-7b58-a0e8-5268-5f7db8e8ccaa@uni-muenster.de
2017-01-24 17:06:34 -05:00
Bruce Momjian
1d25779284 Update copyright via script for 2017 2017-01-03 13:48:53 -05:00
Bruce Momjian
60f1e514ad Update manual set of copyright files for 2017 2017-01-03 13:45:17 -05:00
Michael Meskes
4032ef18d0 Fix buffer overflow on particularly named files and clarify documentation about
output file naming.

Patch by Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com>
2016-12-22 08:28:13 +01:00
Tom Lane
92fb649837 Use "%option prefix" to set API names in ecpg's lexer.
Clean up some technical debt left behind by commit 72b1e3a21: instead of
quickly hacking the name of base_yylex() with a #define, set it properly
with "%option prefix".  This causes the names of pgc.l's other exported
symbols to change as well, so run around and modify the outside references
to them as needed.  Similarly, make pgc.l's external references to
base_yylval use that variable's true name instead of a macro.

The reason for doing this now is that the quick-hack solution will fail
with future versions of flex, as reported by Дилян Палаузов.
Hence, back-patch into 9.6 where the previous commit appeared, since
it's likely people will build 9.6 with newer flex versions during
its lifetime.

Discussion: https://postgr.es/m/d845c1af-e18d-6651-178f-9f08cdf37e10@aegee.org
2016-12-11 14:54:25 -05:00
Tom Lane
18f8f784cb Handle empty or all-blank PAGER setting more sanely in psql.
If the PAGER environment variable is set but contains an empty string,
psql would pass it to "sh" which would silently exit, causing whatever
query output we were printing to vanish entirely.  This is quite
mystifying; it took a long time for us to figure out that this was the
cause of Joseph Brenner's trouble report.  Rather than allowing that
to happen, we should treat this as another way to specify "no pager".
(We could alternatively treat it as selecting the default pager, but
it seems more likely that the former is what the user meant to achieve
by setting PAGER this way.)

Nonempty, but all-white-space, PAGER values have the same behavior, and
it's pretty easy to test for that, so let's handle that case the same way.

Most other cases of faulty PAGER values will result in the shell printing
some kind of complaint to stderr, which should be enough to diagnose the
problem, so we don't need to work harder than this.  (Note that there's
been an intentional decision not to be very chatty about apparent failure
returns from the pager process, since that may happen if, eg, the user
quits the pager with control-C or some such.  I'd just as soon not start
splitting hairs about which exit codes might merit making our own report.)

libpq's old PQprint() function was already on board with ignoring empty
PAGER values, but for consistency, make it ignore all-white-space values
as well.

It's been like this a long time, so back-patch to all supported branches.

Discussion: https://postgr.es/m/CAFfgvXWLOE2novHzYjmQK8-J6TmHz42G8f3X0SORM44+stUGmw@mail.gmail.com
2016-12-07 12:19:56 -05:00
Robert Haas
a0ae54df9b libpq: Fix another bug in 721f7bd3cb.
If we failed to connect to one or more hosts, and then afterwards we
find one that fails to be read-write, the latter error message was
clobbering any earlier ones.  Repair.

Mithun Cy, slightly revised by me.
2016-12-05 14:11:52 -05:00
Robert Haas
11003eb556 libpq: Fix inadvertent change in PQhost() behavior.
Commit 274bb2b385 caused PQhost() to
return the value of the hostaddr parameter rather than the relevant
host when the latter parameter was specified.  That's wrong.  Commit
9a1d0af4ad then amplified the damage by
using PQhost() in more places, so that the SSL test suite started
failing.

Report by Andreas Karlsson; patch by me.
2016-12-01 14:36:39 -05:00
Robert Haas
721f7bd3cb libpq: Add target_session_attrs parameter.
Commit 274bb2b385 made it possible to
specify multiple IPs in a connection string, but that's not good
enough for the case where you have a read-write master and a bunch of
read-only standbys and want to connect to whichever server is the
master at the current time.  This commit allows that, by making it
possible to specify target_session_attrs=read-write as a connection
parameter.

There was extensive discussion of the best name for the connection
parameter and its values as well as the best way to distinguish master
and standbys.  For now, adopt the same solution as JDBC: if the user
wants a read-write connection, issue 'show transaction_read_only' and
rejection the connection if the result is 'on'.  In the future, we
could add additional values of this new target_session_attrs parameter
that issue different queries; or we might have some way of
distinguishing the server type without resorting to an SQL query; but
right now, we have this, and that's (hopefully) a good start.

Victor Wagner and Mithun Cy.  Design review by Álvaro Herrera, Catalin
Iacob, Takayuki Tsunakawa, and Craig Ringer; code review by me.  I
changed Mithun's patch to skip all remaining IPs for a host if we
reject a connection based on this new parameter, rewrote the
documentation, and did some other cosmetic cleanup.

Discussion: http://postgr.es/m/CAD__OuhqPRGpcsfwPHz_PDqAGkoqS1UvnUnOnAB-LBWBW=wu4A@mail.gmail.com
2016-11-29 12:18:31 -05:00
Robert Haas
9a1d0af4ad Code review for commit 274bb2b385.
Avoid memory leak in conninfo_uri_parse_options.  Use the current host
rather than the comma-separated list of host names when the host name
is needed for GSS, SSPI, or SSL authentication.  Document the way
connect_timeout interacts with multiple host specifications.

Takayuki Tsunakawa
2016-11-22 15:50:39 -05:00
Tom Lane
0a7481930c Allow DOS-style line endings in ~/.pgpass files.
On Windows, libc will mask \r\n line endings for us, since we read the
password file in text mode.  But that doesn't happen on Unix.  People
who share password files across both systems might have \r\n line endings
in a file they use on Unix, so as a convenience, ignore trailing \r.
Per gripe from Josh Berkus.

In passing, put the existing check for empty line somewhere where it's
actually useful, ie after stripping the newline not before.

Vik Fearing, adjusted a bit by me

Discussion: <0de37763-5843-b2cc-855e-5d0e5df25807@agliodbs.com>
2016-11-15 16:17:19 -05:00
Peter Eisentraut
a0f357e570 psql: Split up "Modifiers" column in \d and \dD
Make separate columns "Collation", "Nullable", "Default".

Reviewed-by: Kuntal Ghosh <kuntalghosh.2007@gmail.com>
2016-11-03 14:02:46 -04:00
Robert Haas
274bb2b385 libpq: Allow connection strings and URIs to specify multiple hosts.
It's also possible to specify a separate port for each host.

Previously, we'd loop over every address returned by looking up the
host name; now, we'll try every address for every host name.

Patch by me.  Victor Wagner wrote an earlier patch for this feature,
which I read, but I didn't use any of his code.  Review by Mithun Cy.
2016-11-03 09:25:20 -04:00