Does your signed_pb:decode_sign(Msg) function expect the binary to be
in external term format? I would guess you probably want the direct
value there without the term to binary - it should already be a binary.
Is your hook expected to work with allow_mult=true, if so the
get_metadata and get_value calls could get badmatch errors if called
with siblings.
Jon
On Mon, Dec 7, 2015 at 1:52 AM David Rogers
<predictivestatm...@gmail.com <mailto:predictivestatm...@gmail.com>>
wrote:
Hello,
I'm using riak {release,"riak","2.1.0","5.10.3",
[{kernel,"2.16.3",
"$HOME/src/riak-2.1.1/rel/riak/lib/kernel-2.16.3"} ...}
on a cluster with 1 Linux 3.16.0-38 and 4 OSX machines.
I have installed the following pre-commit hook (see end of email) to
validate protobuf-formatted values whose key should be the
sha1-hash of
part of their payload.
props =
{"props":{"allow_mult":false,"basic_quorum":false,"big_vclock":50,"chash_keyfun":{"mod":"riak_core_util","fun":"chash_std_keyfun"},"dvv_enabled":false,"dw":"quorum","last_write_wins":false,"linkfun":{"mod":"riak_kv_wm_link_walker","fun":"mapreduce_linkfun"},"n_val":3,"name":"sil/code","notfound_ok":true,"old_vclock":86400,"postcommit":[],"pr":0,"precommit":[{"mod":"validate_hash","fun":"validate"}],"pw":0,"r":"quorum","rw":"quorum","small_vclock":50,"w":"quorum","write_once":false,"young_vclock":20}})
I attached the failed data element. I'm using the riak-c-client to
interface.
Although almost everything I've added to the bucket this way has
worked so far, a few (like the sample I sent) fail, with riak_put
returning only the unhelpful ERIAK_SERVER_ERROR ("An error was
returned
from the server"). This happens even though manually running the
validation works fine. It is consistently reproducible on this input.
In my attempt to track down the error, I added a test at the end of
riak_sync_request (below) that will log all server errors. The only
problem is that cfg->log_fn is always NULL when riak_log_error is
called, rather than what I set it to initially with
riak_config_set_logging! Gdb can't seem to catch any writes there, so
maybe cfg gets incompletely copied somewhere?
Anyway, I can get out the error message from the debugger.
riak_sync_request (rop_target=rop_target@entry=0x7fffffffe0b0,
response=response@entry=0x7fffffffe130)
at src/riak.c:81
81 riak_log_error(cxn, "%.*s\n", (int)msg->len, msg->data);
(gdb) print msg->data
$13 = (riak_uint8_t *) 0x670a40
"{precommit_fail,{hook_crashed,{validate_hash,validate,error,badarg}}}"
so the server error shows only that the precommit hook
(validate_hash:validate/1) crashes. Again, manually running doesn't
crash it...
Questions:
First, I don't understand why riak-c-client doesn't call the
function
I supplied to riak_config_set_logging. Second, I don't know where to
look for more details on why the pre-commit hook crashes only when I
actually try to add this particular key/value. Can anyone spot a
problem
in its error handling or suggest a way to debug?
Note: I get slightly more info. when posting from curl,
$ curl -XPOST
http://127.0.0.1:8098/types/default/buckets/sil%2Fcode/keys/$hash -H
'Content-Type: application/octet-stream' --data-binary @"$hash"
<html><head><title>500 Internal Server
Error</title></head><body><h1>Internal Server Error</h1>The server
encountered an error while processing this request:<br><pre>{error,
{error,badarg,
[{erlang,iolist_to_binary,
[{hook_crashed,{validate_hash,validate,error,badarg}}],
[]},
{wrq,append_to_response_body,2,[{file,"src/wrq.erl"},{line,215}]},
{riak_kv_wm_object,handle_common_error,3,
[{file,"src/riak_kv_wm_object.erl"},{line,1178}]},
{webmachine_resource,resource_call,3,
[{file,"src/webmachine_resource.erl"},{line,186}]},
{webmachine_resource,do,3,
[{file,"src/webmachine_resource.erl"},{line,142}]},
{webmachine_decision_core,resource_call,1,
[{file,"src/webmachine_decision_core.erl"},{line,48}]},
{webmachine_decision_core,decision,1,
[{file,"src/webmachine_decision_core.erl"},{line,490}]},
{webmachine_decision_core,handle_request,2,
[{file,"src/webmachine_decision_core.erl"},{line,33}]}]}}</pre><P><HR><ADDRESS>mochiweb+webmachine
web server</ADDRESS></body></html>
Sincerely,
~ David M. Rogers
signed.proto:
```
message sign {
required bytes signer = 1;
required uint32 dig_alg = 2;
required bytes sign = 3;
required uint64 ctime = 4;
optional uint32 flags = 5;
optional bytes obj = 10;
}
```
validate_hash.erl:
```
-module(validate_hash).
-export([validate/1, ck_hash/2, start/0]).
%-on_load(load_proto/0).
-author("David M. Rogers <predictivestatm...@gmail.com
<mailto:predictivestatm...@gmail.com>>").
%load_proto() ->
% protobuffs_compile:scan_file("signed.proto").
validate(Object) ->
try
dict:is_key(<<"X-Riak-Deleted">>,
riak_object:get_metadata(Object)) of
true -> Object;
false -> correct_hash(Object)
catch
error:Error ->
{fail, "Invalid Commit: " ++
binary_to_list(list_to_binary(io_lib:format("~p", [Error])))}
end.
correct_hash(Object) ->
Msg = term_to_binary(riak_object:get_value(Object)),
Hash = binary_to_list(riak_object:key(Object)),
case ck_hash(Hash, Msg) of
true -> Object;
false -> {fail, "Invalid Commit: Bad hash value."}
end.
%% Hash : string of 40 hex chars
%% Msg : protocol buffer sign message (signed.proto)
%% returns bool
ck_hash(Hash, Msg) ->
Obj = signed_pb:decode_sign(Msg), %% signed and sobject come from
file naming
Digest = crypto:hash(sha, element(7,Obj)),
bin_to_hexstr(Digest) == Hash
.
bin_to_hexstr(Bin) ->
lists:flatten([io_lib:format("~2.16.0b", [X]) ||
X <- binary_to_list(Bin)]).
hexstr_to_bin(S) ->
hexstr_to_bin(S, []).
hexstr_to_bin([], Acc) ->
list_to_binary(lists:reverse(Acc));
hexstr_to_bin([X,Y|T], Acc) ->
{ok, [V], []} = io_lib:fread("~16u", [X,Y]),
hexstr_to_bin(T, [V | Acc]).
start() ->
Hash = "fc144f6728c994a10309a922d0fd9758b9999cc4",
{ok, Msg} = file:read_file(Hash),
Ret = ck_hash(Hash, Msg),
io:fwrite( "Returned: ~p.~n", [Ret] ).
```
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