cpython/Doc/library/socket.rst
Christian Heimes 81ee3efede Merged revisions 62425-62429,62434-62436,62441,62444,62446-62448,62450-62455,62463,62465-62466,62469,62474,62476-62478,62480,62485,62492,62497-62498,62500,62507,62513-62514,62516,62521,62531,62535,62545-62546,62548-62551,62553-62559,62569,62574,62577,62593,62595,62604-62606,62608,62616,62626-62627,62636,62638,62644-62645,62647-62648,62651-62653,62656,62661,62663,62680,62686-62687,62696,62699-62703,62711 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

................
  r62425 | andrew.kuchling | 2008-04-21 03:45:57 +0200 (Mon, 21 Apr 2008) | 1 line

  Comment typo
................
  r62426 | mark.dickinson | 2008-04-21 03:55:50 +0200 (Mon, 21 Apr 2008) | 2 lines

  Silence 'r may be used uninitialized' compiler warning.
................
  r62427 | andrew.kuchling | 2008-04-21 04:08:00 +0200 (Mon, 21 Apr 2008) | 1 line

  Markup fix
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  r62428 | andrew.kuchling | 2008-04-21 04:08:13 +0200 (Mon, 21 Apr 2008) | 1 line

  Wording changes
................
  r62429 | andrew.kuchling | 2008-04-21 04:14:24 +0200 (Mon, 21 Apr 2008) | 1 line

  Add various items
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  r62434 | thomas.heller | 2008-04-21 15:46:55 +0200 (Mon, 21 Apr 2008) | 1 line

  Fix typo.
................
  r62435 | david.goodger | 2008-04-21 16:40:22 +0200 (Mon, 21 Apr 2008) | 1 line

  corrections ("reStructuredText" is one word)
................
  r62436 | david.goodger | 2008-04-21 16:43:33 +0200 (Mon, 21 Apr 2008) | 1 line

  capitalization
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  r62441 | gregory.p.smith | 2008-04-21 19:46:40 +0200 (Mon, 21 Apr 2008) | 2 lines

  explicitly flush after the ... since there wasn't a newline
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  r62444 | jeroen.ruigrok | 2008-04-21 22:15:39 +0200 (Mon, 21 Apr 2008) | 2 lines

  Windows x64 also falls under VER_PLATFORM_WIN32_NT.
................
  r62446 | gregory.p.smith | 2008-04-21 23:31:08 +0200 (Mon, 21 Apr 2008) | 3 lines

  If sys.stdin is not a tty, fall back to default_getpass after printing
  a warning instead of failing with a termios.error.
................
  r62447 | mark.dickinson | 2008-04-22 00:32:24 +0200 (Tue, 22 Apr 2008) | 8 lines

  test_math and test_cmath are failing on the FreeBSD 6.2 trunk buildbot,
  apparently because tanh(-0.) loses the sign of zero on that platform.
  If true, this is a bug in FreeBSD.

  Added a configure test to verify this.  I still need to figure out
  how best to deal with this failure.
................
  r62448 | amaury.forgeotdarc | 2008-04-22 00:35:30 +0200 (Tue, 22 Apr 2008) | 7 lines

  Issue 2665: On Windows, sys.stderr does not contain a valid file when running without a console.
  It seems to work, but will fail at the first flush.

  This causes IDLE to crash when too many warnings are printed.

  Will backport.
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  r62450 | benjamin.peterson | 2008-04-22 00:57:00 +0200 (Tue, 22 Apr 2008) | 2 lines

  Fix Sphinx warnings
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  r62451 | mark.dickinson | 2008-04-22 02:54:27 +0200 (Tue, 22 Apr 2008) | 3 lines

  Make configure test for tanh(-0.) == -0. committed in r62447 actually
  work.  (The test wasn't properly linked with libm.  Sigh.)
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  r62452 | benjamin.peterson | 2008-04-22 04:16:03 +0200 (Tue, 22 Apr 2008) | 2 lines

  Various io doc updates
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  r62453 | neal.norwitz | 2008-04-22 07:07:47 +0200 (Tue, 22 Apr 2008) | 1 line

  Add Thomas Lee
................
  r62454 | gregory.p.smith | 2008-04-22 10:08:41 +0200 (Tue, 22 Apr 2008) | 8 lines

  Major improvements:
  * Default to using /dev/tty for the password prompt and input before
    falling back to sys.stdin and sys.stderr.
  * Use sys.stderr instead of sys.stdout.
  * print the 'password may be echoed' warning to stream used to display
    the prompt rather than always sys.stderr.
  * warn() with GetPassWarning when input may be echoed.
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  r62455 | gregory.p.smith | 2008-04-22 10:11:33 +0200 (Tue, 22 Apr 2008) | 2 lines

  update the getpass entry
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  r62463 | amaury.forgeotdarc | 2008-04-22 23:14:41 +0200 (Tue, 22 Apr 2008) | 5 lines

  Issue #2670: urllib2.build_opener() failed when two handlers
  derive the same default base class.

  Will backport.
................
  r62465 | skip.montanaro | 2008-04-23 00:45:09 +0200 (Wed, 23 Apr 2008) | 3 lines

  Factor in documentation changes from issue 1753732.
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  r62466 | gregory.p.smith | 2008-04-23 03:06:42 +0200 (Wed, 23 Apr 2008) | 2 lines

  syntax fixup
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  r62469 | benjamin.peterson | 2008-04-23 22:38:06 +0200 (Wed, 23 Apr 2008) | 2 lines

  #2673 Fix example typo in optparse docs
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  r62474 | martin.v.loewis | 2008-04-24 11:50:50 +0200 (Thu, 24 Apr 2008) | 2 lines

  Add Guilherme Polo.
................
  r62476 | martin.v.loewis | 2008-04-24 15:16:36 +0200 (Thu, 24 Apr 2008) | 3 lines

  Remove Py_Refcnt, Py_Type, Py_Size, as they were added only
  for backwards compatibility, yet 2.5 did not have them at all.
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  r62477 | martin.v.loewis | 2008-04-24 15:17:24 +0200 (Thu, 24 Apr 2008) | 2 lines

  Fix typo.
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  r62478 | martin.v.loewis | 2008-04-24 15:18:03 +0200 (Thu, 24 Apr 2008) | 2 lines

  Add Jesus Cea.
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  r62480 | amaury.forgeotdarc | 2008-04-24 20:07:05 +0200 (Thu, 24 Apr 2008) | 4 lines

  Issue2681: the literal 0o8 was wrongly accepted, and evaluated as float(0.0).
  This happened only when 8 is the first digit.
  Credits go to Lukas Meuser.
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  r62485 | amaury.forgeotdarc | 2008-04-24 22:10:26 +0200 (Thu, 24 Apr 2008) | 5 lines

  Disable gc when running test_trace, or we may record the __del__ of collected objects.

  See http://mail.python.org/pipermail/python-checkins/2008-April/068633.html
  the extra events perfectly match several calls to socket._fileobject.__del__()
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  r62492 | neal.norwitz | 2008-04-25 05:40:17 +0200 (Fri, 25 Apr 2008) | 1 line

  Fix typo (now -> no)
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  r62497 | armin.rigo | 2008-04-25 11:35:18 +0200 (Fri, 25 Apr 2008) | 2 lines

  A new crasher.
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  r62498 | thomas.heller | 2008-04-25 17:44:16 +0200 (Fri, 25 Apr 2008) | 1 line

  Add from_buffer and from_buffer_copy class methods to ctypes types.
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  r62500 | mark.dickinson | 2008-04-25 18:59:09 +0200 (Fri, 25 Apr 2008) | 3 lines

  Issue 2635: fix bug in the fix_sentence_endings option to textwrap.fill.
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  r62507 | benjamin.peterson | 2008-04-25 23:43:56 +0200 (Fri, 25 Apr 2008) | 2 lines

  Allow test_import to work when it is invoked directly
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  r62513 | georg.brandl | 2008-04-26 20:31:07 +0200 (Sat, 26 Apr 2008) | 2 lines

  #2691: document PyLong (s)size_t APIs, patch by Alexander Belopolsky.
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  r62514 | georg.brandl | 2008-04-26 20:32:17 +0200 (Sat, 26 Apr 2008) | 2 lines

  Add missing return type to dealloc.
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  r62516 | alexandre.vassalotti | 2008-04-27 02:52:24 +0200 (Sun, 27 Apr 2008) | 2 lines

  Fixed URL of PEP 205 in weakref's module docstring.
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  r62521 | georg.brandl | 2008-04-27 11:39:59 +0200 (Sun, 27 Apr 2008) | 2 lines

  #2677: add note that not all functions may accept keyword args.
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  r62531 | georg.brandl | 2008-04-27 19:38:55 +0200 (Sun, 27 Apr 2008) | 2 lines

  Use correct XHTML tags.
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  r62535 | benjamin.peterson | 2008-04-27 20:14:39 +0200 (Sun, 27 Apr 2008) | 2 lines

  #2700 Document PyNumber_ToBase
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  r62545 | skip.montanaro | 2008-04-27 22:53:57 +0200 (Sun, 27 Apr 2008) | 1 line

  minor wording changes, rewrap a few lines
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  r62546 | kurt.kaiser | 2008-04-27 23:07:41 +0200 (Sun, 27 Apr 2008) | 7 lines

  Home / Control-A toggles between left margin and end of leading white
  space.  Patch 1196903 Jeff Shute.

  M    idlelib/PyShell.py
  M    idlelib/EditorWindow.py
  M    idlelib/NEWS.txt
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  r62548 | kurt.kaiser | 2008-04-27 23:38:05 +0200 (Sun, 27 Apr 2008) | 2 lines

  Improved AutoCompleteWindow logic.  Patch 2062 Tal Einat.
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  r62549 | kurt.kaiser | 2008-04-27 23:52:19 +0200 (Sun, 27 Apr 2008) | 4 lines

  Autocompletion of filenames now support alternate separators, e.g. the
  '/' char on Windows.  Patch 2061 Tal Einat.
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  r62550 | skip.montanaro | 2008-04-28 00:49:56 +0200 (Mon, 28 Apr 2008) | 6 lines

  A few small changes:
  * The only exception we should catch when trying to import cStringIO is an
    ImportError.
  * Delete the function signatures embedded in the mk*temp docstrings.
  * The tempdir global variable was initialized twice.
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  r62551 | skip.montanaro | 2008-04-28 00:52:02 +0200 (Mon, 28 Apr 2008) | 4 lines

  Wrap some long paragraphs and include the default values for optional
  function parameters.
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  r62553 | skip.montanaro | 2008-04-28 04:57:23 +0200 (Mon, 28 Apr 2008) | 7 lines

  Minor cleanups:
  * Avoid creating unused local variables where we can.  Where we can't prefix
    the unused variables with '_'.
  * Avoid shadowing builtins where it won't change the external interface of a
    function.
  * Use None as default path arg to readmodule and readmodule_ex.
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  r62554 | skip.montanaro | 2008-04-28 04:59:45 +0200 (Mon, 28 Apr 2008) | 6 lines

  Correct documentation to match implementation: "Class" instead of
  "class_descriptor", "Function" instead of "function_descriptor".  Note
  default path value for readmodule*.  Wrap some long paragraphs.  Don't
  mention 'inpackage' which isn't part of the public API.
................
  r62555 | brett.cannon | 2008-04-28 05:23:50 +0200 (Mon, 28 Apr 2008) | 5 lines

  Fix a bug introduced by the warnings rewrite where tracebacks were being
  improperly indented.

  Closes issue #2699.
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  r62556 | skip.montanaro | 2008-04-28 05:25:37 +0200 (Mon, 28 Apr 2008) | 2 lines

  Wrap some long lines.
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  r62557 | skip.montanaro | 2008-04-28 05:27:53 +0200 (Mon, 28 Apr 2008) | 6 lines

  Get rid of _test(), _main(), _debug() and _check().  Tests are no longer
  needed (better set available in Lib/test/test_robotparser.py).  Clean up a
  few PEP 8 nits (compound statements on a single line, whitespace around
  operators).
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  r62558 | brett.cannon | 2008-04-28 06:50:06 +0200 (Mon, 28 Apr 2008) | 3 lines

  Rename the test_traceback_print() function to traceback_print() to prevent
  test_capi from automatically calling the function.
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  r62559 | georg.brandl | 2008-04-28 07:16:30 +0200 (Mon, 28 Apr 2008) | 2 lines

  Fix markup.
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  r62569 | amaury.forgeotdarc | 2008-04-28 23:07:06 +0200 (Mon, 28 Apr 2008) | 5 lines

  test_sundry performs minimal tests (a simple import...) on modules that are not tested otherwise.

  Some of them now have tests and can be removed.
  Only 70 to go...
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  r62574 | andrew.kuchling | 2008-04-29 04:03:54 +0200 (Tue, 29 Apr 2008) | 1 line

  Strip down SSL docs; I'm not managing to get test programs working, so I'll just give a minimal description
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  r62577 | martin.v.loewis | 2008-04-29 08:10:53 +0200 (Tue, 29 Apr 2008) | 2 lines

  Add Rodrigo and Heiko.
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  r62593 | nick.coghlan | 2008-04-30 16:23:36 +0200 (Wed, 30 Apr 2008) | 1 line

  Update command line usage documentation to reflect 2.6 changes (also includes some minor cleanups). Addresses TODO list issue 2258
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  r62595 | andrew.kuchling | 2008-04-30 18:19:55 +0200 (Wed, 30 Apr 2008) | 1 line

  Typo fix
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  r62604 | benjamin.peterson | 2008-04-30 23:03:58 +0200 (Wed, 30 Apr 2008) | 2 lines

  make test_support's captured_output a bit more robust when exceptions happen
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  r62605 | georg.brandl | 2008-04-30 23:08:42 +0200 (Wed, 30 Apr 2008) | 2 lines

  #1748: use functools.wraps instead of rolling own metadata update.
................
  r62606 | benjamin.peterson | 2008-04-30 23:25:55 +0200 (Wed, 30 Apr 2008) | 2 lines

  Remove some from __future__ import with_statements
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  r62608 | benjamin.peterson | 2008-05-01 00:03:36 +0200 (Thu, 01 May 2008) | 2 lines

  Fix typo in whatsnew
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  r62616 | georg.brandl | 2008-05-01 20:24:32 +0200 (Thu, 01 May 2008) | 2 lines

  Fix synopsis.
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  r62626 | brett.cannon | 2008-05-02 04:25:09 +0200 (Fri, 02 May 2008) | 6 lines

  Fix a backwards-compatibility mistake where a new optional argument for
  warnings.showwarning() was being used. This broke pre-existing replacements for
  the function since they didn't support the extra argument.

  Closes issue 2705.
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  r62627 | gregory.p.smith | 2008-05-02 09:26:52 +0200 (Fri, 02 May 2008) | 20 lines

  This should fix issue2632.  A long description of the two competing
  problems is in the bug report (one old, one recently introduced trying
  to fix the old one).  In short:

  buffer data during socket._fileobject.read() and readlines() within a
  cStringIO object instead of a [] of str()s returned from the recv()
  call.

  This prevents excessive memory use due to the size parameter being
  passed to recv() being grossly larger than the actual size of the data
  returned *and* prevents excessive cpu usage due to looping in python
  calling recv() with a very tiny size value if min() is used as the
  previous memory-use bug "fix" did.

  It also documents what the socket._fileobject._rbufsize member is
  actually used for.

  This is a candidate for back porting to 2.5.
................
  r62636 | mark.hammond | 2008-05-02 14:48:15 +0200 (Fri, 02 May 2008) | 2 lines

  #2581: Vista UAC/elevation support for bdist_wininst
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  r62638 | facundo.batista | 2008-05-02 19:39:00 +0200 (Fri, 02 May 2008) | 3 lines


  Fixed some test structures. Thanks Mark Dickinson.
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  r62644 | ronald.oussoren | 2008-05-02 21:45:11 +0200 (Fri, 02 May 2008) | 7 lines

  Fix for issue #2573: Can't change the framework name on OS X builds

  This introduces a new configure option: --with-framework-name=NAME
  (defaulting to 'Python'). This allows you to install several copies
  of the Python framework with different names (such as a normal build
  and a debug build).
................
  r62645 | ronald.oussoren | 2008-05-02 21:58:56 +0200 (Fri, 02 May 2008) | 2 lines

  Finish fix for issue2573, previous patch was incomplete.
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  r62647 | martin.v.loewis | 2008-05-02 23:30:20 +0200 (Fri, 02 May 2008) | 13 lines

  Merged revisions 62263-62646 via svnmerge from
  svn+ssh://pythondev@svn.python.org/sandbox/trunk/2to3/lib2to3

  ........
    r62470 | david.wolever | 2008-04-24 02:11:07 +0200 (Do, 24 Apr 2008) | 3 lines

    Fixed up and applied the patch for #2431 -- speeding up 2to3 with a lookup table.
  ........
    r62646 | martin.v.loewis | 2008-05-02 23:29:27 +0200 (Fr, 02 Mai 2008) | 2 lines

    Fix whitespace.
  ........
................
  r62648 | ronald.oussoren | 2008-05-02 23:42:35 +0200 (Fri, 02 May 2008) | 4 lines

  Fix for #1905: PythonLauncher not working correctly on OSX 10.5/Leopard

  This fixes both Python Launchar and the terminalcommand module.
................
  r62651 | ronald.oussoren | 2008-05-02 23:54:56 +0200 (Fri, 02 May 2008) | 2 lines

  Fix for issue #2520 (cannot import macerrors)
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  r62652 | benjamin.peterson | 2008-05-03 00:12:58 +0200 (Sat, 03 May 2008) | 2 lines

  capitalization nit for reStructuredText
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  r62653 | brett.cannon | 2008-05-03 03:02:41 +0200 (Sat, 03 May 2008) | 2 lines

  Fix some indentation errors.
................
  r62656 | brett.cannon | 2008-05-03 05:19:39 +0200 (Sat, 03 May 2008) | 6 lines

  Fix the C implementation of 'warnings' to infer the filename of the module that
  raised an exception properly when __file__ is not set, __name__ == '__main__',
  and sys.argv[0] is a false value.

  Closes issue2743.
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  r62661 | amaury.forgeotdarc | 2008-05-03 14:21:13 +0200 (Sat, 03 May 2008) | 8 lines

  In test_io, StatefulIncrementalDecoderTest was not part of the test suite.
  And of course, the test failed:
  a bytearray was used without reason in io.TextIOWrapper.tell().

  The difference is that iterating over bytes (i.e. str in python2.6) returns 1-char bytes,
  whereas bytearrays yield integers.
  This code should still work with python3.0
................
  r62663 | benjamin.peterson | 2008-05-03 17:56:42 +0200 (Sat, 03 May 2008) | 2 lines

  The compiling struct is now passed around to all AST helpers (see issue 2720)
................
  r62680 | benjamin.peterson | 2008-05-03 23:35:18 +0200 (Sat, 03 May 2008) | 2 lines

  Moved testing of builtin types out of test_builtin and into type specific modules
................
  r62686 | mark.dickinson | 2008-05-04 04:25:46 +0200 (Sun, 04 May 2008) | 4 lines

  Make sure that Context traps and flags dictionaries have values 0 and 1
  (as documented) rather than True and False.
................
  r62687 | benjamin.peterson | 2008-05-04 05:05:49 +0200 (Sun, 04 May 2008) | 2 lines

  Fix typo in whatsnew
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  r62696 | georg.brandl | 2008-05-04 11:15:04 +0200 (Sun, 04 May 2008) | 2 lines

  #2752: wrong meaning of '' for socket host.
................
  r62699 | christian.heimes | 2008-05-04 13:50:53 +0200 (Sun, 04 May 2008) | 1 line

  Added note that Python requires at least Win2k SP4
................
  r62700 | gerhard.haering | 2008-05-04 14:59:57 +0200 (Sun, 04 May 2008) | 3 lines

  SQLite requires 64-bit integers in order to build. So the whole HAVE_LONG_LONG
  #ifdefing was useless.
................
  r62701 | gerhard.haering | 2008-05-04 15:15:12 +0200 (Sun, 04 May 2008) | 3 lines

  Applied sqliterow-richcmp.diff patch from Thomas Heller in Issue2152. The
  sqlite3.Row type is now correctly hashable.
................
  r62702 | gerhard.haering | 2008-05-04 15:42:44 +0200 (Sun, 04 May 2008) | 5 lines

  Implemented feature request 2157: Converter names are cut off at '('
  characters. This avoids the common case of something like 'NUMBER(10)' not
  being parsed as 'NUMBER', like expected. Also corrected the docs about
  converter names being case-sensitive. They aren't any longer.
................
  r62703 | georg.brandl | 2008-05-04 17:45:05 +0200 (Sun, 04 May 2008) | 2 lines

  #2757: Remove spare newline.
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  r62711 | benjamin.peterson | 2008-05-04 21:10:02 +0200 (Sun, 04 May 2008) | 2 lines

  Fix typo in bugs.rst
................
2008-05-04 22:42:01 +00:00

890 lines
35 KiB
ReStructuredText

:mod:`socket` --- Low-level networking interface
================================================
.. module:: socket
:synopsis: Low-level networking interface.
This module provides access to the BSD *socket* interface. It is available on
all modern Unix systems, Windows, MacOS, OS/2, and probably additional
platforms.
.. note::
Some behavior may be platform dependent, since calls are made to the operating
system socket APIs.
For an introduction to socket programming (in C), see the following papers: An
Introductory 4.3BSD Interprocess Communication Tutorial, by Stuart Sechrest and
An Advanced 4.3BSD Interprocess Communication Tutorial, by Samuel J. Leffler et
al, both in the UNIX Programmer's Manual, Supplementary Documents 1 (sections
PS1:7 and PS1:8). The platform-specific reference material for the various
socket-related system calls are also a valuable source of information on the
details of socket semantics. For Unix, refer to the manual pages; for Windows,
see the WinSock (or Winsock 2) specification. For IPv6-ready APIs, readers may
want to refer to :rfc:`3493` titled Basic Socket Interface Extensions for IPv6.
.. index:: object: socket
The Python interface is a straightforward transliteration of the Unix system
call and library interface for sockets to Python's object-oriented style: the
:func:`socket` function returns a :dfn:`socket object` whose methods implement
the various socket system calls. Parameter types are somewhat higher-level than
in the C interface: as with :meth:`read` and :meth:`write` operations on Python
files, buffer allocation on receive operations is automatic, and buffer length
is implicit on send operations.
Socket addresses are represented as follows: A single string is used for the
:const:`AF_UNIX` address family. A pair ``(host, port)`` is used for the
:const:`AF_INET` address family, where *host* is a string representing either a
hostname in Internet domain notation like ``'daring.cwi.nl'`` or an IPv4 address
like ``'100.50.200.5'``, and *port* is an integral port number. For
:const:`AF_INET6` address family, a four-tuple ``(host, port, flowinfo,
scopeid)`` is used, where *flowinfo* and *scopeid* represents ``sin6_flowinfo``
and ``sin6_scope_id`` member in :const:`struct sockaddr_in6` in C. For
:mod:`socket` module methods, *flowinfo* and *scopeid* can be omitted just for
backward compatibility. Note, however, omission of *scopeid* can cause problems
in manipulating scoped IPv6 addresses. Other address families are currently not
supported. The address format required by a particular socket object is
automatically selected based on the address family specified when the socket
object was created.
For IPv4 addresses, two special forms are accepted instead of a host address:
the empty string represents :const:`INADDR_ANY`, and the string
``'<broadcast>'`` represents :const:`INADDR_BROADCAST`. The behavior is not
available for IPv6 for backward compatibility, therefore, you may want to avoid
these if you intend to support IPv6 with your Python programs.
If you use a hostname in the *host* portion of IPv4/v6 socket address, the
program may show a nondeterministic behavior, as Python uses the first address
returned from the DNS resolution. The socket address will be resolved
differently into an actual IPv4/v6 address, depending on the results from DNS
resolution and/or the host configuration. For deterministic behavior use a
numeric address in *host* portion.
AF_NETLINK sockets are represented as pairs ``pid, groups``.
Linux-only support for TIPC is also available using the :const:`AF_TIPC`
address family. TIPC is an open, non-IP based networked protocol designed
for use in clustered computer environments. Addresses are represented by a
tuple, and the fields depend on the address type. The general tuple form is
``(addr_type, v1, v2, v3 [, scope])``, where:
- *addr_type* is one of TIPC_ADDR_NAMESEQ, TIPC_ADDR_NAME, or
TIPC_ADDR_ID.
- *scope* is one of TIPC_ZONE_SCOPE, TIPC_CLUSTER_SCOPE, and
TIPC_NODE_SCOPE.
- If *addr_type* is TIPC_ADDR_NAME, then *v1* is the server type, *v2* is
the port identifier, and *v3* should be 0.
If *addr_type* is TIPC_ADDR_NAMESEQ, then *v1* is the server type, *v2*
is the lower port number, and *v3* is the upper port number.
If *addr_type* is TIPC_ADDR_ID, then *v1* is the node, *v2* is the
reference, and *v3* should be set to 0.
All errors raise exceptions. The normal exceptions for invalid argument types
and out-of-memory conditions can be raised; errors related to socket or address
semantics raise the error :exc:`socket.error`.
Non-blocking mode is supported through :meth:`setblocking`. A generalization of
this based on timeouts is supported through :meth:`settimeout`.
The module :mod:`socket` exports the following constants and functions:
.. exception:: error
.. index:: module: errno
This exception is raised for socket-related errors. The accompanying value is
either a string telling what went wrong or a pair ``(errno, string)``
representing an error returned by a system call, similar to the value
accompanying :exc:`os.error`. See the module :mod:`errno`, which contains names
for the error codes defined by the underlying operating system.
.. exception:: herror
This exception is raised for address-related errors, i.e. for functions that use
*h_errno* in the C API, including :func:`gethostbyname_ex` and
:func:`gethostbyaddr`.
The accompanying value is a pair ``(h_errno, string)`` representing an error
returned by a library call. *string* represents the description of *h_errno*, as
returned by the :cfunc:`hstrerror` C function.
.. exception:: gaierror
This exception is raised for address-related errors, for :func:`getaddrinfo` and
:func:`getnameinfo`. The accompanying value is a pair ``(error, string)``
representing an error returned by a library call. *string* represents the
description of *error*, as returned by the :cfunc:`gai_strerror` C function. The
*error* value will match one of the :const:`EAI_\*` constants defined in this
module.
.. exception:: timeout
This exception is raised when a timeout occurs on a socket which has had
timeouts enabled via a prior call to :meth:`settimeout`. The accompanying value
is a string whose value is currently always "timed out".
.. data:: AF_UNIX
AF_INET
AF_INET6
These constants represent the address (and protocol) families, used for the
first argument to :func:`socket`. If the :const:`AF_UNIX` constant is not
defined then this protocol is unsupported.
.. data:: SOCK_STREAM
SOCK_DGRAM
SOCK_RAW
SOCK_RDM
SOCK_SEQPACKET
These constants represent the socket types, used for the second argument to
:func:`socket`. (Only :const:`SOCK_STREAM` and :const:`SOCK_DGRAM` appear to be
generally useful.)
.. data:: SO_*
SOMAXCONN
MSG_*
SOL_*
IPPROTO_*
IPPORT_*
INADDR_*
IP_*
IPV6_*
EAI_*
AI_*
NI_*
TCP_*
Many constants of these forms, documented in the Unix documentation on sockets
and/or the IP protocol, are also defined in the socket module. They are
generally used in arguments to the :meth:`setsockopt` and :meth:`getsockopt`
methods of socket objects. In most cases, only those symbols that are defined
in the Unix header files are defined; for a few symbols, default values are
provided.
.. data:: SIO_*
RCVALL_*
Constants for Windows' WSAIoctl(). The constants are used as arguments to the
:meth:`ioctl` method of socket objects.
.. data:: TIPC_*
TIPC related constants, matching the ones exported by the C socket API. See
the TIPC documentation for more information.
.. data:: has_ipv6
This constant contains a boolean value which indicates if IPv6 is supported on
this platform.
.. function:: create_connection(address[, timeout])
Connects to the *address* received (as usual, a ``(host, port)`` pair), with an
optional timeout for the connection. Especially useful for higher-level
protocols, it is not normally used directly from application-level code.
Passing the optional *timeout* parameter will set the timeout on the socket
instance (if it is not given or ``None``, the global default timeout setting is
used).
.. function:: getaddrinfo(host, port[, family[, socktype[, proto[, flags]]]])
Resolves the *host*/*port* argument, into a sequence of 5-tuples that contain
all the necessary argument for the sockets manipulation. *host* is a domain
name, a string representation of IPv4/v6 address or ``None``. *port* is a string
service name (like ``'http'``), a numeric port number or ``None``.
The rest of the arguments are optional and must be numeric if specified. For
*host* and *port*, by passing either an empty string or ``None``, you can pass
``NULL`` to the C API. The :func:`getaddrinfo` function returns a list of
5-tuples with the following structure:
``(family, socktype, proto, canonname, sockaddr)``
*family*, *socktype*, *proto* are all integer and are meant to be passed to the
:func:`socket` function. *canonname* is a string representing the canonical name
of the *host*. It can be a numeric IPv4/v6 address when :const:`AI_CANONNAME` is
specified for a numeric *host*. *sockaddr* is a tuple describing a socket
address, as described above. See the source for :mod:`socket` and other
library modules for a typical usage of the function.
.. function:: getfqdn([name])
Return a fully qualified domain name for *name*. If *name* is omitted or empty,
it is interpreted as the local host. To find the fully qualified name, the
hostname returned by :func:`gethostbyaddr` is checked, then aliases for the
host, if available. The first name which includes a period is selected. In
case no fully qualified domain name is available, the hostname as returned by
:func:`gethostname` is returned.
.. function:: gethostbyname(hostname)
Translate a host name to IPv4 address format. The IPv4 address is returned as a
string, such as ``'100.50.200.5'``. If the host name is an IPv4 address itself
it is returned unchanged. See :func:`gethostbyname_ex` for a more complete
interface. :func:`gethostbyname` does not support IPv6 name resolution, and
:func:`getaddrinfo` should be used instead for IPv4/v6 dual stack support.
.. function:: gethostbyname_ex(hostname)
Translate a host name to IPv4 address format, extended interface. Return a
triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the primary
host name responding to the given *ip_address*, *aliaslist* is a (possibly
empty) list of alternative host names for the same address, and *ipaddrlist* is
a list of IPv4 addresses for the same interface on the same host (often but not
always a single address). :func:`gethostbyname_ex` does not support IPv6 name
resolution, and :func:`getaddrinfo` should be used instead for IPv4/v6 dual
stack support.
.. function:: gethostname()
Return a string containing the hostname of the machine where the Python
interpreter is currently executing. If you want to know the current machine's IP
address, you may want to use ``gethostbyname(gethostname())``. This operation
assumes that there is a valid address-to-host mapping for the host, and the
assumption does not always hold. Note: :func:`gethostname` doesn't always return
the fully qualified domain name; use ``getfqdn()`` (see above).
.. function:: gethostbyaddr(ip_address)
Return a triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the
primary host name responding to the given *ip_address*, *aliaslist* is a
(possibly empty) list of alternative host names for the same address, and
*ipaddrlist* is a list of IPv4/v6 addresses for the same interface on the same
host (most likely containing only a single address). To find the fully qualified
domain name, use the function :func:`getfqdn`. :func:`gethostbyaddr` supports
both IPv4 and IPv6.
.. function:: getnameinfo(sockaddr, flags)
Translate a socket address *sockaddr* into a 2-tuple ``(host, port)``. Depending
on the settings of *flags*, the result can contain a fully-qualified domain name
or numeric address representation in *host*. Similarly, *port* can contain a
string port name or a numeric port number.
.. function:: getprotobyname(protocolname)
Translate an Internet protocol name (for example, ``'icmp'``) to a constant
suitable for passing as the (optional) third argument to the :func:`socket`
function. This is usually only needed for sockets opened in "raw" mode
(:const:`SOCK_RAW`); for the normal socket modes, the correct protocol is chosen
automatically if the protocol is omitted or zero.
.. function:: getservbyname(servicename[, protocolname])
Translate an Internet service name and protocol name to a port number for that
service. The optional protocol name, if given, should be ``'tcp'`` or
``'udp'``, otherwise any protocol will match.
.. function:: getservbyport(port[, protocolname])
Translate an Internet port number and protocol name to a service name for that
service. The optional protocol name, if given, should be ``'tcp'`` or
``'udp'``, otherwise any protocol will match.
.. function:: socket([family[, type[, proto]]])
Create a new socket using the given address family, socket type and protocol
number. The address family should be :const:`AF_INET` (the default),
:const:`AF_INET6` or :const:`AF_UNIX`. The socket type should be
:const:`SOCK_STREAM` (the default), :const:`SOCK_DGRAM` or perhaps one of the
other ``SOCK_`` constants. The protocol number is usually zero and may be
omitted in that case.
.. function:: socketpair([family[, type[, proto]]])
Build a pair of connected socket objects using the given address family, socket
type, and protocol number. Address family, socket type, and protocol number are
as for the :func:`socket` function above. The default family is :const:`AF_UNIX`
if defined on the platform; otherwise, the default is :const:`AF_INET`.
Availability: Unix.
.. function:: fromfd(fd, family, type[, proto])
Duplicate the file descriptor *fd* (an integer as returned by a file object's
:meth:`fileno` method) and build a socket object from the result. Address
family, socket type and protocol number are as for the :func:`socket` function
above. The file descriptor should refer to a socket, but this is not checked ---
subsequent operations on the object may fail if the file descriptor is invalid.
This function is rarely needed, but can be used to get or set socket options on
a socket passed to a program as standard input or output (such as a server
started by the Unix inet daemon). The socket is assumed to be in blocking mode.
Availability: Unix.
.. function:: ntohl(x)
Convert 32-bit positive integers from network to host byte order. On machines
where the host byte order is the same as network byte order, this is a no-op;
otherwise, it performs a 4-byte swap operation.
.. function:: ntohs(x)
Convert 16-bit positive integers from network to host byte order. On machines
where the host byte order is the same as network byte order, this is a no-op;
otherwise, it performs a 2-byte swap operation.
.. function:: htonl(x)
Convert 32-bit positive integers from host to network byte order. On machines
where the host byte order is the same as network byte order, this is a no-op;
otherwise, it performs a 4-byte swap operation.
.. function:: htons(x)
Convert 16-bit positive integers from host to network byte order. On machines
where the host byte order is the same as network byte order, this is a no-op;
otherwise, it performs a 2-byte swap operation.
.. function:: inet_aton(ip_string)
Convert an IPv4 address from dotted-quad string format (for example,
'123.45.67.89') to 32-bit packed binary format, as a string four characters in
length. This is useful when conversing with a program that uses the standard C
library and needs objects of type :ctype:`struct in_addr`, which is the C type
for the 32-bit packed binary this function returns.
If the IPv4 address string passed to this function is invalid,
:exc:`socket.error` will be raised. Note that exactly what is valid depends on
the underlying C implementation of :cfunc:`inet_aton`.
:func:`inet_aton` does not support IPv6, and :func:`getnameinfo` should be used
instead for IPv4/v6 dual stack support.
.. function:: inet_ntoa(packed_ip)
Convert a 32-bit packed IPv4 address (a string four characters in length) to its
standard dotted-quad string representation (for example, '123.45.67.89'). This
is useful when conversing with a program that uses the standard C library and
needs objects of type :ctype:`struct in_addr`, which is the C type for the
32-bit packed binary data this function takes as an argument.
If the string passed to this function is not exactly 4 bytes in length,
:exc:`socket.error` will be raised. :func:`inet_ntoa` does not support IPv6, and
:func:`getnameinfo` should be used instead for IPv4/v6 dual stack support.
.. function:: inet_pton(address_family, ip_string)
Convert an IP address from its family-specific string format to a packed, binary
format. :func:`inet_pton` is useful when a library or network protocol calls for
an object of type :ctype:`struct in_addr` (similar to :func:`inet_aton`) or
:ctype:`struct in6_addr`.
Supported values for *address_family* are currently :const:`AF_INET` and
:const:`AF_INET6`. If the IP address string *ip_string* is invalid,
:exc:`socket.error` will be raised. Note that exactly what is valid depends on
both the value of *address_family* and the underlying implementation of
:cfunc:`inet_pton`.
Availability: Unix (maybe not all platforms).
.. function:: inet_ntop(address_family, packed_ip)
Convert a packed IP address (a string of some number of characters) to its
standard, family-specific string representation (for example, ``'7.10.0.5'`` or
``'5aef:2b::8'``) :func:`inet_ntop` is useful when a library or network protocol
returns an object of type :ctype:`struct in_addr` (similar to :func:`inet_ntoa`)
or :ctype:`struct in6_addr`.
Supported values for *address_family* are currently :const:`AF_INET` and
:const:`AF_INET6`. If the string *packed_ip* is not the correct length for the
specified address family, :exc:`ValueError` will be raised. A
:exc:`socket.error` is raised for errors from the call to :func:`inet_ntop`.
Availability: Unix (maybe not all platforms).
.. function:: getdefaulttimeout()
Return the default timeout in floating seconds for new socket objects. A value
of ``None`` indicates that new socket objects have no timeout. When the socket
module is first imported, the default is ``None``.
.. function:: setdefaulttimeout(timeout)
Set the default timeout in floating seconds for new socket objects. A value of
``None`` indicates that new socket objects have no timeout. When the socket
module is first imported, the default is ``None``.
.. data:: SocketType
This is a Python type object that represents the socket object type. It is the
same as ``type(socket(...))``.
.. seealso::
Module :mod:`SocketServer`
Classes that simplify writing network servers.
.. _socket-objects:
Socket Objects
--------------
Socket objects have the following methods. Except for :meth:`makefile` these
correspond to Unix system calls applicable to sockets.
.. method:: socket.accept()
Accept a connection. The socket must be bound to an address and listening for
connections. The return value is a pair ``(conn, address)`` where *conn* is a
*new* socket object usable to send and receive data on the connection, and
*address* is the address bound to the socket on the other end of the connection.
.. method:: socket.bind(address)
Bind the socket to *address*. The socket must not already be bound. (The format
of *address* depends on the address family --- see above.)
.. note::
This method has historically accepted a pair of parameters for :const:`AF_INET`
addresses instead of only a tuple. This was never intentional and is no longer
available in Python 2.0 and later.
.. method:: socket.close()
Close the socket. All future operations on the socket object will fail. The
remote end will receive no more data (after queued data is flushed). Sockets are
automatically closed when they are garbage-collected.
.. method:: socket.connect(address)
Connect to a remote socket at *address*. (The format of *address* depends on the
address family --- see above.)
.. note::
This method has historically accepted a pair of parameters for :const:`AF_INET`
addresses instead of only a tuple. This was never intentional and is no longer
available in Python 2.0 and later.
.. method:: socket.connect_ex(address)
Like ``connect(address)``, but return an error indicator instead of raising an
exception for errors returned by the C-level :cfunc:`connect` call (other
problems, such as "host not found," can still raise exceptions). The error
indicator is ``0`` if the operation succeeded, otherwise the value of the
:cdata:`errno` variable. This is useful to support, for example, asynchronous
connects.
.. note::
This method has historically accepted a pair of parameters for :const:`AF_INET`
addresses instead of only a tuple. This was never intentional and is no longer
available in Python 2.0 and later.
.. method:: socket.fileno()
Return the socket's file descriptor (a small integer). This is useful with
:func:`select.select`.
Under Windows the small integer returned by this method cannot be used where a
file descriptor can be used (such as :func:`os.fdopen`). Unix does not have
this limitation.
.. method:: socket.getpeername()
Return the remote address to which the socket is connected. This is useful to
find out the port number of a remote IPv4/v6 socket, for instance. (The format
of the address returned depends on the address family --- see above.) On some
systems this function is not supported.
.. method:: socket.getsockname()
Return the socket's own address. This is useful to find out the port number of
an IPv4/v6 socket, for instance. (The format of the address returned depends on
the address family --- see above.)
.. method:: socket.getsockopt(level, optname[, buflen])
Return the value of the given socket option (see the Unix man page
:manpage:`getsockopt(2)`). The needed symbolic constants (:const:`SO_\*` etc.)
are defined in this module. If *buflen* is absent, an integer option is assumed
and its integer value is returned by the function. If *buflen* is present, it
specifies the maximum length of the buffer used to receive the option in, and
this buffer is returned as a string. It is up to the caller to decode the
contents of the buffer (see the optional built-in module :mod:`struct` for a way
to decode C structures encoded as strings).
.. method:: socket.ioctl(control, option)
:platform: Windows
The :meth:`ioctl` method is a limited interface to the WSAIoctl system
interface. Please refer to the MSDN documentation for more information.
.. method:: socket.listen(backlog)
Listen for connections made to the socket. The *backlog* argument specifies the
maximum number of queued connections and should be at least 1; the maximum value
is system-dependent (usually 5).
.. method:: socket.makefile([mode[, bufsize]])
.. index:: single: I/O control; buffering
Return a :dfn:`file object` associated with the socket. (File objects are
described in :ref:`bltin-file-objects`.) The file object
references a :cfunc:`dup`\ ped version of the socket file descriptor, so the
file object and socket object may be closed or garbage-collected independently.
The socket must be in blocking mode (it can not have a timeout). The optional
*mode* and *bufsize* arguments are interpreted the same way as by the built-in
:func:`file` function.
.. method:: socket.recv(bufsize[, flags])
Receive data from the socket. The return value is a string representing the
data received. The maximum amount of data to be received at once is specified
by *bufsize*. See the Unix manual page :manpage:`recv(2)` for the meaning of
the optional argument *flags*; it defaults to zero.
.. note::
For best match with hardware and network realities, the value of *bufsize*
should be a relatively small power of 2, for example, 4096.
.. method:: socket.recvfrom(bufsize[, flags])
Receive data from the socket. The return value is a pair ``(string, address)``
where *string* is a string representing the data received and *address* is the
address of the socket sending the data. See the Unix manual page
:manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults
to zero. (The format of *address* depends on the address family --- see above.)
.. method:: socket.recvfrom_into(buffer[, nbytes[, flags]])
Receive data from the socket, writing it into *buffer* instead of creating a
new string. The return value is a pair ``(nbytes, address)`` where *nbytes* is
the number of bytes received and *address* is the address of the socket sending
the data. See the Unix manual page :manpage:`recv(2)` for the meaning of the
optional argument *flags*; it defaults to zero. (The format of *address*
depends on the address family --- see above.)
.. method:: socket.recv_into(buffer[, nbytes[, flags]])
Receive up to *nbytes* bytes from the socket, storing the data into a buffer
rather than creating a new string. If *nbytes* is not specified (or 0),
receive up to the size available in the given buffer. See the Unix manual page
:manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults
to zero.
.. method:: socket.send(string[, flags])
Send data to the socket. The socket must be connected to a remote socket. The
optional *flags* argument has the same meaning as for :meth:`recv` above.
Returns the number of bytes sent. Applications are responsible for checking that
all data has been sent; if only some of the data was transmitted, the
application needs to attempt delivery of the remaining data.
.. method:: socket.sendall(string[, flags])
Send data to the socket. The socket must be connected to a remote socket. The
optional *flags* argument has the same meaning as for :meth:`recv` above.
Unlike :meth:`send`, this method continues to send data from *string* until
either all data has been sent or an error occurs. ``None`` is returned on
success. On error, an exception is raised, and there is no way to determine how
much data, if any, was successfully sent.
.. method:: socket.sendto(string[, flags], address)
Send data to the socket. The socket should not be connected to a remote socket,
since the destination socket is specified by *address*. The optional *flags*
argument has the same meaning as for :meth:`recv` above. Return the number of
bytes sent. (The format of *address* depends on the address family --- see
above.)
.. method:: socket.setblocking(flag)
Set blocking or non-blocking mode of the socket: if *flag* is 0, the socket is
set to non-blocking, else to blocking mode. Initially all sockets are in
blocking mode. In non-blocking mode, if a :meth:`recv` call doesn't find any
data, or if a :meth:`send` call can't immediately dispose of the data, a
:exc:`error` exception is raised; in blocking mode, the calls block until they
can proceed. ``s.setblocking(0)`` is equivalent to ``s.settimeout(0)``;
``s.setblocking(1)`` is equivalent to ``s.settimeout(None)``.
.. method:: socket.settimeout(value)
Set a timeout on blocking socket operations. The *value* argument can be a
nonnegative float expressing seconds, or ``None``. If a float is given,
subsequent socket operations will raise an :exc:`timeout` exception if the
timeout period *value* has elapsed before the operation has completed. Setting
a timeout of ``None`` disables timeouts on socket operations.
``s.settimeout(0.0)`` is equivalent to ``s.setblocking(0)``;
``s.settimeout(None)`` is equivalent to ``s.setblocking(1)``.
.. method:: socket.gettimeout()
Return the timeout in floating seconds associated with socket operations, or
``None`` if no timeout is set. This reflects the last call to
:meth:`setblocking` or :meth:`settimeout`.
Some notes on socket blocking and timeouts: A socket object can be in one of
three modes: blocking, non-blocking, or timeout. Sockets are always created in
blocking mode. In blocking mode, operations block until complete. In
non-blocking mode, operations fail (with an error that is unfortunately
system-dependent) if they cannot be completed immediately. In timeout mode,
operations fail if they cannot be completed within the timeout specified for the
socket. The :meth:`setblocking` method is simply a shorthand for certain
:meth:`settimeout` calls.
Timeout mode internally sets the socket in non-blocking mode. The blocking and
timeout modes are shared between file descriptors and socket objects that refer
to the same network endpoint. A consequence of this is that file objects
returned by the :meth:`makefile` method must only be used when the socket is in
blocking mode; in timeout or non-blocking mode file operations that cannot be
completed immediately will fail.
Note that the :meth:`connect` operation is subject to the timeout setting, and
in general it is recommended to call :meth:`settimeout` before calling
:meth:`connect`.
.. method:: socket.setsockopt(level, optname, value)
.. index:: module: struct
Set the value of the given socket option (see the Unix manual page
:manpage:`setsockopt(2)`). The needed symbolic constants are defined in the
:mod:`socket` module (:const:`SO_\*` etc.). The value can be an integer or a
string representing a buffer. In the latter case it is up to the caller to
ensure that the string contains the proper bits (see the optional built-in
module :mod:`struct` for a way to encode C structures as strings).
.. method:: socket.shutdown(how)
Shut down one or both halves of the connection. If *how* is :const:`SHUT_RD`,
further receives are disallowed. If *how* is :const:`SHUT_WR`, further sends
are disallowed. If *how* is :const:`SHUT_RDWR`, further sends and receives are
disallowed.
Note that there are no methods :meth:`read` or :meth:`write`; use :meth:`recv`
and :meth:`send` without *flags* argument instead.
Socket objects also have these (read-only) attributes that correspond to the
values given to the :class:`socket` constructor.
.. attribute:: socket.family
The socket family.
.. attribute:: socket.type
The socket type.
.. attribute:: socket.proto
The socket protocol.
.. _socket-example:
Example
-------
Here are four minimal example programs using the TCP/IP protocol: a server that
echoes all data that it receives back (servicing only one client), and a client
using it. Note that a server must perform the sequence :func:`socket`,
:meth:`bind`, :meth:`listen`, :meth:`accept` (possibly repeating the
:meth:`accept` to service more than one client), while a client only needs the
sequence :func:`socket`, :meth:`connect`. Also note that the server does not
:meth:`send`/:meth:`recv` on the socket it is listening on but on the new
socket returned by :meth:`accept`.
The first two examples support IPv4 only. ::
# Echo server program
import socket
HOST = '' # Symbolic name meaning all available interfaces
PORT = 50007 # Arbitrary non-privileged port
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(1)
conn, addr = s.accept()
print('Connected by', addr)
while True:
data = conn.recv(1024)
if not data: break
conn.send(data)
conn.close()
::
# Echo client program
import socket
HOST = 'daring.cwi.nl' # The remote host
PORT = 50007 # The same port as used by the server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
s.send('Hello, world')
data = s.recv(1024)
s.close()
print('Received', repr(data))
The next two examples are identical to the above two, but support both IPv4 and
IPv6. The server side will listen to the first address family available (it
should listen to both instead). On most of IPv6-ready systems, IPv6 will take
precedence and the server may not accept IPv4 traffic. The client side will try
to connect to the all addresses returned as a result of the name resolution, and
sends traffic to the first one connected successfully. ::
# Echo server program
import socket
import sys
HOST = '' # Symbolic name meaning the local host
PORT = 50007 # Arbitrary non-privileged port
s = None
for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM, 0, socket.AI_PASSIVE):
af, socktype, proto, canonname, sa = res
try:
s = socket.socket(af, socktype, proto)
except socket.error as msg:
s = None
continue
try:
s.bind(sa)
s.listen(1)
except socket.error as msg:
s.close()
s = None
continue
break
if s is None:
print('could not open socket')
sys.exit(1)
conn, addr = s.accept()
print('Connected by', addr)
while True:
data = conn.recv(1024)
if not data: break
conn.send(data)
conn.close()
::
# Echo client program
import socket
import sys
HOST = 'daring.cwi.nl' # The remote host
PORT = 50007 # The same port as used by the server
s = None
for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM):
af, socktype, proto, canonname, sa = res
try:
s = socket.socket(af, socktype, proto)
except socket.error as msg:
s = None
continue
try:
s.connect(sa)
except socket.error as msg:
s.close()
s = None
continue
break
if s is None:
print('could not open socket')
sys.exit(1)
s.send('Hello, world')
data = s.recv(1024)
s.close()
print('Received', repr(data))
The last example shows how to write a very simple network sniffer with raw
sockets on Windows. The example requires administrator priviliges to modify
the interface::
import socket
# the public network interface
HOST = socket.gethostbyname(socket.gethostname())
# create a raw socket and bind it to the public interface
s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_IP)
s.bind((HOST, 0))
# Include IP headers
s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
# receive all packages
s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON)
# receive a package
print s.recvfrom(65565)
# disabled promiscuous mode
s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF)