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%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
%% ex: ts=4 sw=4 et
-module(rebar_pkg_resource).
-behaviour(rebar_resource).
-export([lock/2
,download/3
,needs_update/2
,make_vsn/1]).
-include("rebar.hrl").
lock(_AppDir, Source) ->
Source.
needs_update(Dir, {pkg, _Name, Vsn}) ->
[AppInfo] = rebar_app_discover:find_apps([Dir], all),
case rebar_app_info:original_vsn(AppInfo) =:= ec_cnv:to_list(Vsn) of
true ->
false;
false ->
true
end.
download(TmpDir, Pkg={pkg, Name, Vsn}, State) ->
CDN = rebar_state:get(State, rebar_packages_cdn, ?DEFAULT_CDN),
PackageDir = rebar_packages:package_dir(State),
Package = binary_to_list(<<Name/binary, "-", Vsn/binary, ".tar">>),
CachePath = filename:join(PackageDir, Package),
Url = string:join([CDN, Package], "/"),
cached_download(TmpDir, CachePath, Pkg, Url, etag(CachePath), State).
cached_download(TmpDir, CachePath, Pkg, Url, ETag, State) ->
case request(Url, ETag) of
{ok, cached} ->
serve_from_cache(TmpDir, CachePath, Pkg, State);
{ok, Body, NewETag} ->
serve_from_download(TmpDir, CachePath, Pkg, NewETag, Body, State);
error when ETag =/= false ->
?DEBUG("Download ~s error, using ~s from cache", [Url, CachePath]),
serve_from_cache(TmpDir, CachePath, Pkg, State);
error ->
request_failed
end.
serve_from_cache(TmpDir, CachePath, Pkg, State) ->
{Files, Contents, Version, Meta} = extract(TmpDir, CachePath),
case checksums(Pkg, Files, Contents, Version, Meta, State) of
{Chk, Chk, Chk} ->
ok = erl_tar:extract({binary, Contents}, [{cwd, TmpDir}, compressed]),
{ok, true};
{_Bin, Chk, Chk} ->
?DEBUG("Checksums: registry: ~p, pkg: ~p", [Chk, _Bin]),
{failed_extract, CachePath};
{Chk, _Reg, Chk} ->
?DEBUG("Checksums: registry: ~p, pkg: ~p", [_Reg, Chk]),
{bad_registry_checksum, CachePath};
{_Bin, _Reg, _Tar} ->
?DEBUG("Checksums: registry: ~p, pkg: ~p, meta: ~p", [_Reg, _Bin, _Tar]),
{bad_checksum, CachePath}
end.
serve_from_download(TmpDir, CachePath, Package, ETag, Binary, State) ->
?DEBUG("Writing ~p to cache at ~s", [Package, CachePath]),
file:write_file(CachePath, Binary),
case etag(CachePath) of
ETag ->
serve_from_cache(TmpDir, CachePath, Package, State);
FileETag ->
?DEBUG("Downloaded file ~s ETag ~s doesn't match returned ETag ~s", [CachePath, ETag, FileETag]),
{bad_download, CachePath}
end.
extract(TmpDir, CachePath) ->
ec_file:mkdir_p(TmpDir),
{ok, Files} = erl_tar:extract(CachePath, [memory]),
{"contents.tar.gz", Contents} = lists:keyfind("contents.tar.gz", 1, Files),
{"VERSION", Version} = lists:keyfind("VERSION", 1, Files),
{"metadata.config", Meta} = lists:keyfind("metadata.config", 1, Files),
{Files, Contents, Version, Meta}.
checksums(Pkg, Files, Contents, Version, Meta, State) ->
Blob = <<Version/binary, Meta/binary, Contents/binary>>,
<<X:256/big-unsigned>> = crypto:hash(sha256, Blob),
BinChecksum = list_to_binary(string:to_upper(lists:flatten(io_lib:format("~64.16.0b", [X])))),
RegistryChecksum = rebar_packages:registry_checksum(Pkg, State),
{"CHECKSUM", TarChecksum} = lists:keyfind("CHECKSUM", 1, Files),
{BinChecksum, RegistryChecksum, TarChecksum}.
make_vsn(_) ->
{error, "Replacing version of type pkg not supported."}.
request(Url, ETag) ->
case httpc:request(get, {Url, [{"if-none-match", ETag} || ETag =/= false]},
[{relaxed, true}],
[{body_format, binary}],
rebar) of
{ok, {{_Version, 200, _Reason}, Headers, Body}} ->
?DEBUG("Successfully downloaded ~s", [Url]),
{"etag", ETag1} = lists:keyfind("etag", 1, Headers),
{ok, Body, string:strip(ETag1, both, $")};
{ok, {{_Version, 304, _Reason}, _Headers, _Body}} ->
?DEBUG("Cached copy of ~s still valid", [Url]),
{ok, cached};
{ok, {{_Version, Code, _Reason}, _Headers, _Body}} ->
?DEBUG("Request to ~p failed: status code ~p", [Url, Code]),
error;
{error, Reason} ->
?DEBUG("Request to ~p failed: ~p", [Url, Reason]),
error
end.
etag(Path) ->
case file:read_file(Path) of
{ok, Binary} ->
<<X:128/big-unsigned-integer>> = crypto:hash(md5, Binary),
string:to_lower(lists:flatten(io_lib:format("~32.16.0b", [X])));
{error, _} ->
false
end.
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