Hello,
I was trying to understand the asn1 side of the openssl code.
In
rsa_asn1.c
there is
IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname(RSA, RSAPrivateKey, RSAPrivateKey)
It's implenetation is in
asn1t.h
#define IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname(stname, itname, fname) \
stname *d2i_##fname(stname **a, const unsigned char **in, long len) \
{ \
return (stname *)ASN1_item_d2i((ASN1_VALUE **)a, in, len,
ASN1_ITEM_rptr(itname));\
} \
int i2d_##fname(const stname *a, unsigned char **out) \
{ \
return ASN1_item_i2d((ASN1_VALUE *)a, out,
ASN1_ITEM_rptr(itname));\
}
What's throwing me off is this:
ASN1_ITEM_rptr(itname)
It is defined in asn1.h
#define ASN1_ITEM_rptr(ref) (&(ref##_it))
So based on the above implement statement it turns out to be
&RSAPrivateKey_it
Now where is this guy RSAPrivateKey_it ??.
My global search landed me to:
libeay.num
which shows
RSAPrivateKey_it
2906 EXIST:!EXPORT_VAR_AS_FUNCTION:VARIABLE:RSA
RSAPrivateKey_it
2906 EXIST:EXPORT_VAR_AS_FUNCTION:FUNCTION:RSA
I also see that it is declared in rsa.h
DECLARE_ASN1_ENCODE_FUNCTIONS_const(RSA, RSAPrivateKey)
#define DECLARE_ASN1_ENCODE_FUNCTIONS_const(type, name) \
type *d2i_##name(type **a, const unsigned char **in, long len); \
int i2d_##name(const type *a, unsigned char **out); \
DECLARE_ASN1_ITEM(name)
#define DECLARE_ASN1_ITEM(name) \
OPENSSL_EXTERN const ASN1_ITEM name##_it;
so the complete and correct declaration will be
extern const ASN1_ITEM RSAPrivatekey_it
If someone could PLEASE help me understand this, I will be very grateful.
Thanks a lot
Shravan
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