Implement encoding of fragmented OCTET STRINGs

Decoding of a fragmented OCTET STRING with the size constrained to a
single value is implemented, but encoding is not implemented, and
decoding is not tested in any test case.

There is no urgent need to support encoding of fragmented OCTET STRINGs,
but not being able to encode such values complicates testing of decoding.
For example, eif we add the following type to PrimStrings.asn1 in the test
suite:

  FixedOs65536 ::= OCTET STRING (SIZE (65536))

then asn1ct:test('PrimStrings') will fail because this value cannot
be encoded.

2 files changed, 86 insertions, 13 deletions

diff --git a/lib/asn1/src/asn1rt_per_bin_rt2ct.erl b/lib/asn1/src/asn1rt_per_bin_rt2ct.erl
index dfe03f9c5d..a7536ee88b 100644
--- a/lib/asn1/src/asn1rt_per_bin_rt2ct.erl
+++ b/lib/asn1/src/asn1rt_per_bin_rt2ct.erl
@@ -1312,19 +1312,55 @@ encode_octet_string(SZ={_,_},false,Val) ->
 %    [encode_length(SZ,length(Val)),align,
 %	     {octets,Val}];
     Len = length(Val),
-    [encode_length(SZ,Len),2,
-     octets_to_complete(Len,Val)];
+    try
+	[encode_length(SZ,Len),2,
+	 octets_to_complete(Len,Val)]
+    catch
+	exit:{error,{asn1,{encode_length,_}}} ->
+	    encode_fragmented_octet_string(Val)
+    end;
 encode_octet_string(SZ,false,Val) when is_list(SZ) ->
     Len = length(Val),
-    [encode_length({hd(SZ),lists:max(SZ)},Len),2,
-     octets_to_complete(Len,Val)];
+    try
+	[encode_length({hd(SZ),lists:max(SZ)},Len),2,
+	 octets_to_complete(Len,Val)]
+    catch
+	exit:{error,{asn1,{encode_length,_}}} ->
+	    encode_fragmented_octet_string(Val)
+    end;
+encode_octet_string(Sv,false,Val) when is_integer(Sv) ->
+    encode_fragmented_octet_string(Val);
 encode_octet_string(no,false,Val) ->
     Len = length(Val),
-    [encode_length(undefined,Len),2,
-     octets_to_complete(Len,Val)];
+    try
+	[encode_length(undefined,Len),2,
+	 octets_to_complete(Len,Val)]
+    catch
+	exit:{error,{asn1,{encode_length,_}}} ->
+	    encode_fragmented_octet_string(Val)
+    end;
 encode_octet_string(C,_,_) ->
     exit({error,{not_implemented,C}}).
 
+encode_fragmented_octet_string(Val) ->
+    Bin = iolist_to_binary(Val),
+    efos_1(Bin).
+
+efos_1(<<B1:16#C000/binary,B2:16#4000/binary,T/binary>>) ->
+    [20,1,<<3:2,4:6>>,
+     octets_to_complete(16#C000, B1),
+     octets_to_complete(16#4000, B2)|efos_1(T)];
+efos_1(<<B:16#C000/binary,T/binary>>) ->
+    [20,1,<<3:2,3:6>>,octets_to_complete(16#C000, B)|efos_1(T)];
+efos_1(<<B:16#8000/binary,T/binary>>) ->
+    [20,1,<<3:2,2:6>>,octets_to_complete(16#8000, B)|efos_1(T)];
+efos_1(<<B:16#4000/binary,T/binary>>) ->
+    [20,1,<<3:2,1:6>>,octets_to_complete(16#4000, B)|efos_1(T)];
+efos_1(<<>>) ->
+    [20,1,0];
+efos_1(<<B/bitstring>>) ->
+    Len = byte_size(B),
+    [encode_length(undefined, Len),octets_to_complete(Len, B)].
 
 decode_octet_string(Bytes,Range) ->
     decode_octet_string(Bytes,Range,false).
diff --git a/lib/asn1/src/asn1rt_uper_bin.erl b/lib/asn1/src/asn1rt_uper_bin.erl
index 6f6bfa195e..2cd68c62a0 100644
--- a/lib/asn1/src/asn1rt_uper_bin.erl
+++ b/lib/asn1/src/asn1rt_uper_bin.erl
@@ -582,7 +582,7 @@ encode_length(undefined,Len) -> % un-constrained
 	Len < 16384 ->
 	    <<2:2,Len:14>>;
 	true  -> % should be able to endode length >= 16384
-	    exit({error,{asn1,{encode_length,{nyi,above_16k}}}})
+	    error({error,{asn1,{encode_length,{nyi,above_16k}}}})
     end;
 
 encode_length({0,'MAX'},Len) ->
@@ -1052,16 +1052,53 @@ encode_octet_string(C,Val) ->
 	    list_to_binary(Val);
 	2 ->
 	    list_to_binary(Val);
-	Sv when Sv =<65535, Sv == length(Val) -> % fixed length
-	    list_to_binary(Val);
-	VR = {_,_}  ->
-	    [encode_length(VR,length(Val)),list_to_binary(Val)];
+	{_,_}=VR  ->
+	    try
+		[encode_length(VR, length(Val)),list_to_binary(Val)]
+	    catch
+		error:{error,{asn1,{encode_length,_}}} ->
+		    encode_fragmented_octet_string(Val)
+	    end;
+	Sv when is_integer(Sv), Sv =:= length(Val) -> % fixed length
+	    if
+		Sv =< 65535 ->
+		    list_to_binary(Val);
+		true ->
+		    encode_fragmented_octet_string(Val)
+	    end;
 	Sv when is_list(Sv) ->
-	    [encode_length({hd(Sv),lists:max(Sv)},length(Val)),list_to_binary(Val)];
+	    try
+		[encode_length({hd(Sv),lists:max(Sv)},
+			       length(Val)),list_to_binary(Val)]
+	    catch
+		error:{error,{asn1,{encode_length,_}}} ->
+		    encode_fragmented_octet_string(Val)
+	    end;
 	no  ->
-	    [encode_length(undefined,length(Val)),list_to_binary(Val)]
+	    try
+		[encode_length(undefined, length(Val)),list_to_binary(Val)]
+	    catch
+		error:{error,{asn1,{encode_length,_}}} ->
+		    encode_fragmented_octet_string(Val)
+	    end
     end.
 
+encode_fragmented_octet_string(Val) ->
+    Bin = list_to_binary(Val),
+    efos_1(Bin).
+
+efos_1(<<B:16#10000/binary,T/binary>>) ->
+    [<<3:2,4:6>>,B|efos_1(T)];
+efos_1(<<B:16#C000/binary,T/binary>>) ->
+    [<<3:2,3:6>>,B|efos_1(T)];
+efos_1(<<B:16#8000/binary,T/binary>>) ->
+    [<<3:2,2:6>>,B|efos_1(T)];
+efos_1(<<B:16#4000/binary,T/binary>>) ->
+    [<<3:2,1:6>>,B|efos_1(T)];
+efos_1(<<B/bitstring>>) ->
+    Len = byte_size(B),
+    [encode_length(undefined, Len),B].
+
 decode_octet_string(Bytes,C) ->
     decode_octet_string1(Bytes,get_constraint(C,'SizeConstraint')).
 decode_octet_string1(<<B1,Bytes/bitstring>>,1) ->