Correct encoding (decoding) of lengths less than the root range

Given the type:

  S ::= IA5String (SIZE (5, ...))

attempting to encode (to PER/UPER) a string shorter than 5 characters
would fail. Similarly, attempting to decode such string in the BER
format would fail.

In the case of BER, we can do no range checks if the size constraint
is extensible.

5 files changed, 21 insertions, 8 deletions

diff --git a/lib/asn1/src/asn1rtt_ber.erl b/lib/asn1/src/asn1rtt_ber.erl
index 5fbf116747..34f246fb22 100644
--- a/lib/asn1/src/asn1rtt_ber.erl
+++ b/lib/asn1/src/asn1rtt_ber.erl
@@ -1270,12 +1270,7 @@ check_restricted_string(Val, StrLen, Range) ->
     case Range of
 	{Lb,Ub} when StrLen >= Lb, Ub >= StrLen -> % variable length constraint
 	    Val;
-	{{Lb,_Ub},[]} when StrLen >= Lb ->
-	    Val;
-	{{Lb,_Ub},_Ext=[Min|_]} when StrLen >= Lb; StrLen >= Min ->
-	    Val;
-	{{Lb1,Ub1},{Lb2,Ub2}} when StrLen >= Lb1, StrLen =< Ub1;
-				   StrLen =< Ub2, StrLen >= Lb2 ->
+	{_,Ext} when is_list(Ext) ->
 	    Val;
 	StrLen -> % fixed length constraint
 	    Val;
diff --git a/lib/asn1/src/asn1rtt_per.erl b/lib/asn1/src/asn1rtt_per.erl
index b8971b7c33..d5952755f8 100644
--- a/lib/asn1/src/asn1rtt_per.erl
+++ b/lib/asn1/src/asn1rtt_per.erl
@@ -356,7 +356,7 @@ encode_length({Lb,Ub}=Vr, Len) when Ub =< 65535 ,Lb >= 0 -> % constrained
 encode_length({Lb,_Ub}, Len) when is_integer(Lb), Lb >= 0 -> % Ub > 65535
     encode_length(Len);
 encode_length({{Lb,Ub}=Vr,Ext}, Len)
-  when Ub =< 65535 ,Lb >= 0,Len=<Ub, is_list(Ext) ->
+  when Ub =< 65535, Lb =< Len, Len =< Ub, is_list(Ext) ->
     %% constrained extensible
     [0|encode_constrained_number(Vr,Len)];
 encode_length({{_,_},Ext},Len) when is_list(Ext) ->
diff --git a/lib/asn1/src/asn1rtt_uper.erl b/lib/asn1/src/asn1rtt_uper.erl
index 3f362d227e..0a543ea6d7 100644
--- a/lib/asn1/src/asn1rtt_uper.erl
+++ b/lib/asn1/src/asn1rtt_uper.erl
@@ -355,7 +355,7 @@ encode_length({Lb,Ub}=Vr, Len) when Ub =< 65535, Lb >= 0 -> % constrained
 encode_length({Lb,_Ub}, Len) when is_integer(Lb), Lb >= 0 -> % Ub > 65535
     encode_length(Len);
 encode_length({{Lb,Ub}=Vr,Ext},Len)
-  when Ub =< 65535, Lb >= 0, Len =< Ub, is_list(Ext) ->
+  when Ub =< 65535, Lb =< Len, Len =< Ub, is_list(Ext) ->
     %% constrained extensible
     [<<0:1>>,encode_constrained_number(Vr,Len)];
 encode_length({{_Lb,_Ub},Ext}, Len) when is_list(Ext) ->
diff --git a/lib/asn1/test/asn1_SUITE_data/Constraints.py b/lib/asn1/test/asn1_SUITE_data/Constraints.py
index 87243121f7..a069364084 100644
--- a/lib/asn1/test/asn1_SUITE_data/Constraints.py
+++ b/lib/asn1/test/asn1_SUITE_data/Constraints.py
@@ -86,5 +86,6 @@ Document ::= OCTET STRING (ENCODED BY pdf)
 
 pdf OBJECT IDENTIFIER ::= {1,2,3,4,5}
 
+ShorterExt ::= IA5String (SIZE (5, ...))
 
 END
diff --git a/lib/asn1/test/testConstraints.erl b/lib/asn1/test/testConstraints.erl
index d6db1c2b91..d245f6d1d5 100644
--- a/lib/asn1/test/testConstraints.erl
+++ b/lib/asn1/test/testConstraints.erl
@@ -145,8 +145,16 @@ int_constraints(Rules) ->
     [roundtrip('VariableSize', lists:seq($A, $A+L-1)) ||
 	L <- lists:seq(1, 10)],
 
+    roundtrip_enc('ShorterExt', "a", shorter_ext(Rules, "a")),
+    roundtrip('ShorterExt', "abcde"),
+    roundtrip('ShorterExt', "abcdef"),
+
     ok.
 
+shorter_ext(per, "a") -> <<16#80,16#01,16#61>>;
+shorter_ext(uper, "a") -> <<16#80,16#E1>>;
+shorter_ext(ber, _) -> none.
+
 refed_NNL_name(_Erule) ->
     ?line {ok,_} = asn1_wrapper:encode('Constraints','AnotherThing',fred),
     ?line {error,_Reason} = 
@@ -160,6 +168,15 @@ roundtrip(Module, Type, Value) ->
     {ok,Value} = Module:decode(Type, Encoded),
     ok.
 
+roundtrip_enc(Type, Value, Enc) ->
+    Module = 'Constraints',
+    {ok,Encoded} = Module:encode(Type, Value),
+    {ok,Value} = Module:decode(Type, Encoded),
+    case Enc of
+	none -> ok;
+	Encoded -> ok
+    end.
+
 range_error(ber, Type, Value) ->
     %% BER: Values outside the effective range should be rejected
     %% on decode.