Fix broken handling of default values for BIT STRINGs

For DER/PER/UPER, a value equal to the DEFAULT is not supposed to
be encoded.

BIT STRINGs values can be represented as Erlang terms in four
different ways: as an integer, as a list of zeroes and ones,
as a {Unused,Binary} tuple, or as an Erlang bitstring.

When encoding a BIT STRING, only certain representations of
BIT STRINGs values were recognized. All representations must
be recognized.

When decoding a DEFAULT value for a BIT STRING, the actual value
given in the decoding would be either an integer or a list
of zeroes and one (depending on how the literal was written in
the specification). We expect that the default value should be
in the same representation as any other BIT STRING value (i.e.
by default an Erlang bitstring, or a list if the 'legacy_bitstring'
option has been given, or as compact bitstring if 'compact_bitstring'
has been given).

1 files changed, 35 insertions, 6 deletions

diff --git a/lib/asn1/test/testPrimStrings.erl b/lib/asn1/test/testPrimStrings.erl
index be5409aa92..2fe0780701 100644
--- a/lib/asn1/test/testPrimStrings.erl
+++ b/lib/asn1/test/testPrimStrings.erl
@@ -19,7 +19,7 @@
 %%
 -module(testPrimStrings).
 
--export([bit_string/1]).
+-export([bit_string/2]).
 -export([octet_string/1]).
 -export([numeric_string/1]).
 -export([other_strings/1]).
@@ -68,7 +68,7 @@ fragmented_lengths() ->
      K64-1,K64,K64+1,K64+(1 bsl 7)-1,K64+(1 bsl 7),K64+(1 bsl 7)+1,
      K64+K16-1,K64+K16,K64+K16+1].
 
-bit_string(Rules) ->
+bit_string(Rules, Opts) ->
     
     %%==========================================================
     %% Bs1 ::= BIT STRING
@@ -90,9 +90,10 @@ bit_string(Rules) ->
     bs_roundtrip('Bs1', [0,1,0,0,1,0]),
     bs_roundtrip('Bs1', [1,0,0,0,0,0,0,0,0]),
     bs_roundtrip('Bs1', [0,1,0,0,1,0,1,1,1,1,1,0,0,0,1,0,0,1,1]),
-    
-    case Rules of
-	ber ->
+
+
+    case {Rules,Opts} of
+	{ber,[]} ->
 	    bs_decode('Bs1', <<35,8,3,2,0,73,3,2,4,32>>,
 		      [0,1,0,0,1,0,0,1,0,0,1,0]),
 	    bs_decode('Bs1', <<35,9,3,2,0,234,3,3,7,156,0>>,
@@ -100,7 +101,17 @@ bit_string(Rules) ->
 	    bs_decode('Bs1', <<35,128,3,2,0,234,3,3,7,156,0,0,0>>,
 		      [1,1,1,0,1,0,1,0,1,0,0,1,1,1,0,0,0]);
 	_ ->
-	    ok
+	    %% DER, PER, UPER
+	    consistent_def_enc('BsDef1',
+			       [2#111101,
+				[1,0,1,1,1,1],
+				{2,<<2#101111:6,0:2>>},
+				<<2#101111:6>>]),
+	    consistent_def_enc('BsDef2',
+			       [[1,1,0,1, 1,1,1,0, 1,0,1,0, 1,1,0,1,
+				 1,0,1,1, 1,1,1,0, 1,1,1,0, 1,1,1,1],
+				{0,<<16#DEADBEEF:4/unit:8>>},
+				<<16#DEADBEEF:4/unit:8>>])
     end,
 
     
@@ -217,6 +228,24 @@ bit_string(Rules) ->
 	_ -> per_bs_strings()
     end.
 
+consistent_def_enc(Type, Vs) ->
+    M = 'PrimStrings',
+    {ok,Enc} = M:encode(Type, {Type,asn1_DEFAULT}),
+    {ok,Val} = M:decode(Type, Enc),
+
+    %% Ensure that the value has the correct format.
+    case {M:bit_string_format(),Val} of
+	{bitstring,{_,Bs}} when is_bitstring(Bs) -> ok;
+	{compact,{_,{Unused,Bin}}} when is_integer(Unused),
+					is_binary(Bin) -> ok;
+	{legacy,{_,Bs}} when is_list(Bs) -> ok
+    end,
+
+    %% All values should be recognized and encoded as the
+    %% the default value (i.e. not encoded at all).
+    _ = [{ok,Enc} = M:encode(Type, {Type,V}) || V <- Vs],
+    ok.
+
 %% The PER encoding rules requires that a BIT STRING with
 %% named positions should never have any trailing zeroes
 %% (except to reach the minimum number of bits as given by