From b9f59ca2986075112ff1de42320168affa10921e Mon Sep 17 00:00:00 2001
From: Jason David Davies <jasondavies@apache.org>
Date: Tue, 12 Jan 2010 19:29:23 +0000
Subject: Add utility for verifying hashes.

git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@898477 13f79535-47bb-0310-9956-ffa450edef68
---
 src/couchdb/couch_httpd_auth.erl | 32 +++++++++++++++++++-------------
 src/couchdb/couch_util.erl       | 17 +++++++++++++++++
 2 files changed, 36 insertions(+), 13 deletions(-)

(limited to 'src/couchdb')

diff --git a/src/couchdb/couch_httpd_auth.erl b/src/couchdb/couch_httpd_auth.erl
index a1222df4..5c87f427 100644
--- a/src/couchdb/couch_httpd_auth.erl
+++ b/src/couchdb/couch_httpd_auth.erl
@@ -71,8 +71,9 @@ default_authentication_handler(Req) ->
             UserProps ->
                 UserSalt = proplists:get_value(<<"salt">>, UserProps, <<>>),
                 PasswordHash = hash_password(?l2b(Pass), UserSalt),
-                case proplists:get_value(<<"password_sha">>, UserProps, nil) of
-                    ExpectedHash when ExpectedHash == PasswordHash ->                        
+                ExpectedHash = proplists:get_value(<<"password_sha">>, UserProps, nil),
+                case couch_util:verify(ExpectedHash, PasswordHash) of
+                    true ->
                         Req#httpd{user_ctx=#user_ctx{
                             name=?l2b(User),
                             roles=proplists:get_value(<<"roles">>, UserProps, []),
@@ -268,15 +269,19 @@ cookie_authentication_handler(#httpd{mochi_req=MochiReq}=Req) ->
                 Timeout = to_int(couch_config:get("couch_httpd_auth", "timeout", 600)),
                 ?LOG_DEBUG("timeout ~p", [Timeout]),
                 case (catch erlang:list_to_integer(TimeStr, 16)) of
-                    TimeStamp when CurrentTime < TimeStamp + Timeout
-                    andalso ExpectedHash == Hash ->
-                        TimeLeft = TimeStamp + Timeout - CurrentTime,
-                        ?LOG_DEBUG("Successful cookie auth as: ~p", [User]),
-                        Req#httpd{user_ctx=#user_ctx{
-                            name=?l2b(User),
-                            roles=proplists:get_value(<<"roles">>, UserProps, []),
-                            user_doc=proplists:get_value(<<"user_doc">>, UserProps, null)
-                        }, auth={FullSecret, TimeLeft < Timeout*0.9}};
+                    TimeStamp when CurrentTime < TimeStamp + Timeout ->
+                        case couch_util:verify(ExpectedHash, Hash) of
+                            true ->
+                                TimeLeft = TimeStamp + Timeout - CurrentTime,
+                                ?LOG_DEBUG("Successful cookie auth as: ~p", [User]),
+                                Req#httpd{user_ctx=#user_ctx{
+                                    name=?l2b(User),
+                                    roles=proplists:get_value(<<"roles">>, UserProps, []),
+                                    user_doc=proplists:get_value(<<"user_doc">>, UserProps, null)
+                                }, auth={FullSecret, TimeLeft < Timeout*0.9}};
+                            _Else ->
+                                Req
+                        end;
                     _Else ->
                         Req
                 end
@@ -344,8 +349,9 @@ handle_session_req(#httpd{method='POST', mochi_req=MochiReq}=Req) ->
     end,
     UserSalt = proplists:get_value(<<"salt">>, User, <<>>),
     PasswordHash = hash_password(Password, UserSalt),
-    case proplists:get_value(<<"password_sha">>, User, nil) of
-        ExpectedHash when ExpectedHash == PasswordHash ->
+    ExpectedHash = proplists:get_value(<<"password_sha">>, User, nil),
+    case couch_util:verify(ExpectedHash, PasswordHash) of
+        true ->
             % setup the session cookie
             Secret = ?l2b(ensure_cookie_auth_secret()),
             {NowMS, NowS, _} = erlang:now(),
diff --git a/src/couchdb/couch_util.erl b/src/couchdb/couch_util.erl
index 6edfb781..45d1d336 100644
--- a/src/couchdb/couch_util.erl
+++ b/src/couchdb/couch_util.erl
@@ -21,6 +21,7 @@
 -export([file_read_size/1, get_nested_json_value/2, json_user_ctx/1]).
 -export([to_binary/1, to_integer/1, to_list/1, url_encode/1]).
 -export([json_encode/1, json_decode/1]).
+-export([verify/2]).
 
 -include("couch_db.hrl").
 -include_lib("kernel/include/file.hrl").
@@ -423,3 +424,19 @@ json_decode(V) ->
         _Type:_Error ->
             throw({invalid_json,V})
     end.
+
+verify([X|RestX], [Y|RestY], Result) ->
+    verify(RestX, RestY, (X bxor Y) bor Result);
+verify([], [], Result) ->
+    Result == 0.
+
+verify(<<X/binary>>, <<Y/binary>>) ->
+    verify(?b2l(X), ?b2l(Y));
+verify(X, Y) when is_list(X) and is_list(Y) ->
+    case length(X) == length(Y) of
+        true ->
+            verify(X, Y, 0);
+        false ->
+            false
+    end;
+verify(_X, _Y) -> false.
-- 
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