Add ssl_crl_hash_dir module

This module is an implementation of the ssl_crl_cache_api behaviour.
It can be used when there is a directory containing CRLs for all
relevant CAs, in the form used by e.g. Apache.  The module assumes
that the directory is being updated through an external process.

1 files changed, 106 insertions, 0 deletions

diff --git a/lib/ssl/src/ssl_crl_hash_dir.erl b/lib/ssl/src/ssl_crl_hash_dir.erl
new file mode 100644
index 0000000000..bb62737232
--- /dev/null
+++ b/lib/ssl/src/ssl_crl_hash_dir.erl
@@ -0,0 +1,106 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2016-2016. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+
+-module(ssl_crl_hash_dir).
+
+-include_lib("public_key/include/public_key.hrl").
+
+-behaviour(ssl_crl_cache_api).
+
+-export([lookup/3, select/2, fresh_crl/2]).
+
+lookup(#'DistributionPoint'{cRLIssuer = CRLIssuer} = DP, CertIssuer, CRLDbInfo) ->
+    Issuer =
+	case CRLIssuer of
+	    asn1_NOVALUE ->
+		%% If the distribution point extension doesn't
+		%% indicate a CRL issuer, use the certificate issuer.
+		CertIssuer;
+	    _ ->
+		CRLIssuer
+	end,
+    %% Find all CRLs for this issuer, and return those that match the
+    %% given distribution point.
+    AllCRLs = select(Issuer, CRLDbInfo),
+    lists:filter(fun(DER) ->
+			 public_key:pkix_match_dist_point(DER, DP)
+		 end, AllCRLs).
+
+fresh_crl(#'DistributionPoint'{}, CurrentCRL) ->
+    CurrentCRL.
+
+select(Issuer, {_DbHandle, [{dir, Dir}]}) ->
+    case find_crls(Issuer, Dir) of
+        [_|_] = DERs ->
+	    DERs;
+        [] ->
+            %% That's okay, just report that we didn't find any CRL.
+            %% If the crl_check setting is best_effort, ssl_handshake
+            %% is happy with that, but if it's true, this is an error.
+            [];
+        {error, Error} ->
+            error_logger:error_report(
+              [{cannot_find_crl, Error},
+               {dir, Dir},
+               {module, ?MODULE},
+               {line, ?LINE}]),
+            []
+    end.
+
+find_crls(Issuer, Dir) ->
+    case filelib:is_dir(Dir) of
+        true ->
+	    Hash = public_key:short_name_hash(Issuer),
+	    find_crls(Issuer, Hash, Dir, 0, []);
+        false ->
+            {error, not_a_directory}
+    end.
+
+find_crls(Issuer, Hash, Dir, N, Acc) ->
+    Filename = filename:join(Dir, Hash ++ ".r" ++ integer_to_list(N)),
+    case file:read_file(Filename) of
+	{error, enoent} ->
+	    Acc;
+	{ok, Bin} ->
+	    try maybe_parse_pem(Bin) of
+		DER when is_binary(DER) ->
+		    %% Found one file.  Let's see if there are more.
+		    find_crls(Issuer, Hash, Dir, N + 1, [DER] ++ Acc)
+	    catch
+		error:Error ->
+		    %% Something is wrong with the file.  Report
+		    %% it, and try the next one.
+		    error_logger:error_report(
+		      [{crl_parse_error, Error},
+		       {filename, Filename},
+		       {module, ?MODULE},
+		       {line, ?LINE}]),
+		    find_crls(Issuer, Hash, Dir, N + 1, Acc)
+	    end
+    end.
+
+maybe_parse_pem(<<"-----BEGIN", _/binary>> = PEM) ->
+    %% It's a PEM encoded file.  Need to extract the DER
+    %% encoded data.
+    [{'CertificateList', DER, not_encrypted}] = public_key:pem_decode(PEM),
+    DER;
+maybe_parse_pem(DER) when is_binary(DER) ->
+    %% Let's assume it's DER-encoded.
+    DER.
+