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%%% Copyright (c) 2017, NORDUnet A/S.
%%% See LICENSE for licensing information.
-module(merge_sth).
-behaviour(gen_server).
-export([start_link/1]).
-export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
code_change/3]).
-include("plop.hrl").
-record(state, {
timer :: reference()
}).
start_link(Args) ->
gen_server:start_link(?MODULE, Args, []).
init([]) ->
lager:info("~p: starting", [?MODULE]),
{ok, #state{timer = erlang:start_timer(1000, self(), make_sth)}}.
handle_call(stop, _From, State) ->
{stop, normal, stopped, State}.
handle_cast(_Request, State) ->
{noreply, State}.
handle_info({timeout, _Timer, make_sth}, State) ->
make_sth(read_sth_treesize(), State).
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
terminate(Reason, #state{timer = Timer}) ->
lager:info("~p terminating: ~p", [?MODULE, Reason]),
erlang:cancel_timer(Timer),
ok.
%%%%%%%%%%%%%%%%%%%%
make_sth(noentry, State) ->
case merge_util:readfile(minsize_path) of
noentry ->
lager:error("This log is invalid, missing both sth and minsize."),
exit({shutdown, invalid_log});
{struct, PropList} ->
MinSize = proplists:get_value(<<"size">>, PropList),
make_sth(MinSize, State)
end;
make_sth(CurSize, State) ->
{MergeSecondaryNames, _MergeSecondaryAddrs} =
lists:unzip(plopconfig:get_env(merge_secondaries, [])),
lager:info("Current STH at ~B with ~B secondary merge nodes.",
[CurSize, length(MergeSecondaryNames)]),
%% Collect tree sizes from verified.* files in a list, add an
%% entry with the size found in the 'fetched' file, sort the list
%% (highest tree size first) and index it with backup quorum to
%% get our new tree size.
Sizes = [merge_util:nfetched() | verified_sizes(MergeSecondaryNames)],
BackupQuorumSize = plopconfig:get_env(backup_quorum, 0),
true = BackupQuorumSize =< length(MergeSecondaryNames),
NewSize = lists:nth(BackupQuorumSize + 1, Sizes),
lager:debug("new size at backup quorum ~B: ~B", [BackupQuorumSize, NewSize]),
Wait =
case NewSize < CurSize of
true ->
statusreport:report("merge_sth", http_auth:own_name(), "sth", null),
lager:debug("waiting for enough backups to reach ~B, now at ~B",
[CurSize, NewSize]),
1;
false ->
ok = do_make_sth(NewSize),
application:get_env(plop, merge_delay, 600)
end,
Timer = erlang:start_timer(Wait * 1000, self(), make_sth),
{noreply, State#state{timer = Timer}}.
do_make_sth(Size) ->
%% Build a new sth file in memory, get a signature for it and
%% verify both the new sth file against the signature and the new
%% root against ht before writing to disk.
NewTimestamp = plop:generate_timestamp(),
NewRoot = root(Size),
PackedSignature = make_signature(NewTimestamp, Size, NewRoot),
ok = case plop:verify_sth(Size, NewTimestamp, NewRoot, PackedSignature) of
true ->
NewSTH = [{"tree_size", Size},
{"timestamp", NewTimestamp},
{"sha256_root_hash", base64:encode(NewRoot)},
{"tree_head_signature", base64:encode(PackedSignature)}],
ok = plop:save_sth({struct, NewSTH}),
statusreport:report("merge_sth", http_auth:own_name(), "sth", Size),
ok;
false ->
lager:error("The signature we got for new tree of size ~B doesn't " ++
"verify corectly; timestamp=~p; tree head: ~p",
[Size, NewTimestamp, NewRoot]),
sig_mismatch
end.
make_signature(Timestamp, Size, Roothash) ->
SigType = plop:signature_type(tree_hash),
Sig = sign:sign_sth(
<<0:8, % CT protocol version (v1).
SigType:8,
Timestamp:64,
Size:64,
Roothash/binary>>),
plop:serialise(#signature{
algorithm = #sig_and_hash_alg{
hash_alg = sha256,
signature_alg = ecdsa},
signature = Sig}).
verified_sizes(MergeSecondaryNodeNames) ->
{ok, BasePath} = application:get_env(plop, verified_path),
L = lists:map(fun(NodeName) ->
verified_size(BasePath ++ "." ++ NodeName)
end, MergeSecondaryNodeNames),
lists:reverse(lists:sort(L)).
verified_size(Path) ->
case atomic:readfile(Path) of
noentry ->
0;
Contents ->
case mochijson2:decode(Contents) of
{struct, PropList} ->
Size = proplists:get_value(<<"tree_size">>, PropList),
Hash = hex:hexstr_to_bin(binary_to_list(proplists:get_value(<<"sha256_root_hash">>, PropList))),
ok = validate_tree_head(Size, Hash),
Size
end
end.
validate_tree_head(Treesize, Roothash) ->
ok = case root(Treesize) of
Roothash ->
ok;
RoothashInTree ->
lager:error("Root hash doesn't match tree head version ~B: ~p != ~p", [Treesize - 1, Roothash, RoothashInTree]),
root_mismatch
end.
read_sth_treesize() ->
case plop:sth() of
noentry ->
noentry;
{struct, STH} ->
Treesize = proplists:get_value(<<"tree_size">>, STH),
Timestamp = proplists:get_value(<<"timestamp">>, STH),
RootHash = base64:decode(proplists:get_value(<<"sha256_root_hash">>, STH)),
Signature = base64:decode(proplists:get_value(<<"tree_head_signature">>, STH)),
true = plop:verify_sth(Treesize, Timestamp, RootHash, Signature),
Treesize
end.
root(TreeSize) ->
ht:load_tree(TreeSize - 1),
ht:root(TreeSize - 1).
|
