-module(awssign).
-author('eric@ohmforce.com').
-include_lib("xmerl/include/xmerl.hrl").
-export([sign_and_send/5, describe_instances/5]).
sign_and_send(Params, Host,APIVersion, AccessKey, SecretKey)->
SortedParams = sort([{"Timestamp", create_timestamp()},
{"SignatureVersion", "2"},
{"Version", APIVersion},
{"AWSAccessKeyId", AccessKey},
{"SignatureMethod", "HmacSHA1"}
|Params]),
EncodedParams = lists:foldl(
fun({K,V}, Acc)->
[url_encode(K) ++ "=" ++ url_encode(V)| Acc]
end,[], SortedParams),
QueryString = string:join(EncodedParams, "&"),
ToSign = "GET\n" ++ Host ++ "\n/\n" ++ QueryString,
Signature = url_encode(
binary_to_list(
base64:encode(crypto:sha_mac(SecretKey, ToSign)))
),
URL = "http://"++ Host ++ "/?" ++ QueryString ++ "&Signature=" ++ Signature,
case http:request(URL) of
{ok, {{_Version, 200, _ReasonPhrase}, _Headers, Body}} -> {ok, Body};
{ok, {{_Version, Code, ReasonPhrase}, _Headers, _Body}} -> {error, {Code, ReasonPhrase} }
end.
% lifted from http://code.google.com/p/erlawys/source/browse/trunk/src/aws_util.erl
create_timestamp() -> create_timestamp(calendar:now_to_universal_time(now())).
create_timestamp({{Y, M, D}, {H, Mn, S}}) ->
to_str(Y) ++ "-" ++ to_str(M) ++ "-" ++ to_str(D) ++ "T" ++
to_str(H) ++ ":" ++ to_str(Mn)++ ":" ++ to_str(S) ++ "Z".
add_zeros(L) -> if length(L) == 1 -> [$0|L]; true -> L end.
to_str(L) -> add_zeros(integer_to_list(L)).
sort(Params)->
lists:sort(fun({A, _}, {X, _}) -> A > X end, Params).
describe_instances(SecurityGroup, Host,APIVersion, AccessKey, SecretKey)->
Params =[ {"Action", "DescribeInstances"}],
Res = sign_and_send(Params, Host, APIVersion, AccessKey, SecretKey),
case Res of
{ok, XML} ->
{R,_} = xmerl_scan:string(XML),
[ V#xmlText.value
|| V<- xmerl_xpath:string("/DescribeInstancesResponse/reservationSet/item[ groupSet/item/groupId = \""
++ SecurityGroup ++ "\"]/instancesSet/item/privateDnsName/text()", R)];
{error, E} ->
erlang:error ({ describe_instances_failed, E }),
[]
end.
% lifted from the ever precious yaws_utils.erl
integer_to_hex(I) ->
case catch erlang:integer_to_list(I, 16) of
{'EXIT', _} ->
old_integer_to_hex(I);
Int ->
Int
end.
old_integer_to_hex(I) when I<10 ->
integer_to_list(I);
old_integer_to_hex(I) when I<16 ->
[I-10+$A];
old_integer_to_hex(I) when I>=16 ->
N = trunc(I/16),
old_integer_to_hex(N) ++ old_integer_to_hex(I rem 16).
url_encode([H|T]) ->
if
H >= $a, $z >= H ->
[H|url_encode(T)];
H >= $A, $Z >= H ->
[H|url_encode(T)];
H >= $0, $9 >= H ->
[H|url_encode(T)];
H == $_; H == $.; H == $-; H == $/ -> % FIXME: more..
[H|url_encode(T)];
true ->
case integer_to_hex(H) of
[X, Y] ->
[$%, X, Y | url_encode(T)];
[X] ->
[$%, $0, X | url_encode(T)]
end
end;
url_encode([]) ->
[].
