On 08/12/2011 11:41 AM, Dmitriy Anisimkov wrote:
Is there way to decode binary stream with indefinite number of ASN.1
defined records ?
To know the record length I have to use asn1_get_tag_der and
asn1_get_length_ber.
I made it in Ada.
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function Get_Length
(Data : Stream_Element_Array) return Stream_Element_Count
is
use type C.long;
subtype Offset is Stream_Element_Offset;
Tag_Len, BER_Len : aliased C.int;
cls : aliased C.unsigned_char;
tag : aliased C.unsigned_long;
RC : constant C.int :=
asn1_get_tag_der
(Data (Data'First)'Unrestricted_Access, Data'Length, cls'Access,
Tag_Len'Access, tag'Access);
RL : C.long;
begin
if RC /= ASN1_SUCCESS then
raise Constraint_Error with Error_Message (RC);
end if;
if Tag_Len >= Data'Length then
return 0;
end if;
RL := asn1_get_length_ber
(Data (Data'First + Offset (Tag_Len))'Unrestricted_Access,
Data'Length - Tag_Len, BER_Len'Access);
if RL < 0 then
raise Constraint_Error with Error_Message (C.int (RL));
end if;
RL := RL + C.long (Tag_Len + BER_Len);
if RL > Data'Length then
return 0;
end if;
return Stream_Element_Count (RL);
end Get_Length;
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The better way would be if function asn1_der_decoding (or any similar
new one) returned the decoded record length.
