share/util/resolve_redirections.lua

   1 -- libquvi-scripts
   2 -- Copyright (C) 2012-2013  Toni Gundogdu <legatvs@gmail.com>
   3 --
   4 -- This file is part of libquvi-scripts <http://quvi.sourceforge.net/>.
   5 --
   6 -- This program is free software: you can redistribute it and/or
   7 -- modify it under the terms of the GNU Affero General Public
   8 -- License as published by the Free Software Foundation, either
   9 -- version 3 of the License, or (at your option) any later version.
  10 --
  11 -- This program is distributed in the hope that it will be useful,
  12 -- but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 -- GNU Affero General Public License for more details.
  15 --
  16 -- You should have received a copy of the GNU Affero General
  17 -- Public License along with this program.  If not, see
  18 -- <http://www.gnu.org/licenses/>.
  19 --
  20
  21 local ResolveExceptions = {} -- Utility functions unique to this script
  22
  23 function resolve_redirections(qargs)
  24 --[[
  25
  26 UPDATE (2013-10-07)
  27
  28 libquvi will always attempt to resolve URL redirections.  This means
  29 that quvi_media_new (for example) will always resolve first and only
  30 then pass the input URL to the media scripts to determine the support.
  31
  32 Problem:
  33
  34   - g00gle now redirects the embedded media URLs to the API pages
  35
  36   - This causes libquvi to return the "no support" because the
  37     destination URL looks nothing like a typical media page URL
  38
  39 Solution:
  40
  41   - "normalize" (quvi/youtube) the input URL before we try to resolve
  42     URL redirections
  43
  44   - "normalize" will convert the embedded media URLs to media page URLs,
  45     which can then be passed to libquvi/libcurl for URL resolving
  46
  47 Notes:
  48
  49   - quvi_supports function skips resolving altogether unless online
  50     check is forced
  51
  52   - This is the reason "normalize" must still be called in "ident"
  53     function of the media script, even if we do so here
  54
  55 ]]--
  56   local Y = require 'quvi/youtube'
  57   local u = Y.normalize(qargs.input_url)
  58
  59   -- Have libcurl resolve the URL redirections.
  60   local r = quvi.http.resolve(u)
  61   if #r.resolved_url ==1 then return u end
  62
  63   -- Apply any exception rules to the destination URL.
  64   return ResolveExceptions.YouTube(qargs, r.resolved_url)
  65 end
  66
  67 --
  68 -- Utility functions
  69 --
  70
  71 function ResolveExceptions.YouTube(qargs, dst)
  72   return dst -- UPDATE (2012-11-18): g00gle servers no longer strip the "#t="
  73   --
  74   -- Preserve the #t= (if any) after redirection.
  75   -- e.g. http://www.youtube.com/watch?v=LWxTGJ3TK1U#t=2m22s
  76   --   -> http://www.youtube.com/watch?v=LWxTGJ3TK1U
  77   --
  78 --  return table.concat({dst, (qargs.input_url:match('(#t=%w+)') or '')})
  79 end
  80
  81 -- vim: set ts=2 sw=2 tw=72 expandtab: