Implemented make_link in S3 lib, signed url's

src/erlcloud_s3.erl

@@ -17,7 +17,8 @@
          get_object_torrent/2, get_object_torrent/3,
          get_object_metadata/2, get_object_metadata/3, get_object_metadata/4,
          put_object/3, put_object/4, put_object/5, put_object/6,
-         set_object_acl/3, set_object_acl/4]).
+         set_object_acl/3, set_object_acl/4,
+         make_link/3, make_link/4]).
 
 -include_lib("erlcloud/include/erlcloud.hrl").
 -include_lib("erlcloud/include/erlcloud_aws.hrl").
@@ -553,6 +554,27 @@ set_object_acl(BucketName, Key, ACL, Config)
     XMLText = list_to_binary(xmerl:export_simple([XML], xmerl_xml)),
     s3_simple_request(Config, put, BucketName, [$/|Key], "acl", [], XMLText, []).
 
+-spec make_link(integer(), string(), string()) -> string().
+
+make_link(Expire_time, BucketName, Key) 
+  when is_integer(Expire_time), is_list(BucketName), is_list(Key) ->
+    make_link(Expire_time, BucketName, Key, default_config()).
+
+-spec make_link(integer(), string(), string(), aws_config()) -> string().
+
+make_link(Expire_time, BucketName, Key, Config) 
+  when is_integer(Expire_time), is_list(BucketName), is_list(Key) ->  
+    {Mega, Sec, _Micro} = erlang:now(),
+    Datetime = (Mega * 1000000) + Sec, 
+    Expires = integer_to_list(Expire_time + Datetime),
+    To_sign = lists:flatten(["GET\n\n\n", Expires, "\n/", BucketName, "/", Key]),
+    Sig = base64:encode(crypto:sha_mac(Config#aws_config.secret_access_key, To_sign)),
+    Host = lists:flatten(["http://", BucketName, ".", Config#aws_config.s3_host]),
+    URI = lists:flatten(["/", Key, "?AWSAccessKeyId=", erlcloud_http:url_encode(Config#aws_config.access_key_id), "&Signature=", erlcloud_http:url_encode(Sig), "&Expires=", Expires]),
+    {list_to_integer(Expires), 
+     binary_to_list(erlang:iolist_to_binary(Host)),
+     binary_to_list(erlang:iolist_to_binary(URI))}.
+
 -spec set_bucket_attribute(string(), atom(), term()) -> ok.
 
 set_bucket_attribute(BucketName, AttributeName, Value) ->