Re: body part of function i2d_DHparams()

[Bernhard Froehlich]

LIDA WANG wrote:

I am sorry i keep bothering you guys, but i am stucked here.

function d2i_DHparams() is created in the following macros:


    stname *d2i_##fname(stname **a, const unsigned char **in, long len) \
    { \

    } \
    int i2d_##fname(const stname *a, unsigned char **out) \
    { \

    }

also, we have
#define ASN1_ITEM_rptr(ref) (&(ref##_it))

#define IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname(stname, itname, fname) \ return (stname *)ASN1_item_d2i((ASN1_VALUE **)a, in, len, ASN1_ITEM_rptr(itname));\ return ASN1_item_i2d((ASN1_VALUE *)a, out, ASN1_ITEM_rptr(itname));\ but i can not fine the place where variable or function "DHparams_it" is defined. do you know how to find this variable?

The story just goes on:
dh_asn1.c contains

ASN1_SEQUENCE_cb(DHparams, dh_cb) = {
       ASN1_SIMPLE(DH, p, BIGNUM),
       ASN1_SIMPLE(DH, g, BIGNUM),
       ASN1_OPT(DH, length, ZLONG),
} ASN1_SEQUENCE_END_cb(DH, DHparams)

IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname(DH, DHparams, DHparams)

The whole bunch of macros is defined in asn1t.h:

#define ASN1_SEQUENCE_cb(tname, cb) \
       static const ASN1_AUX tname##_aux = {NULL, 0, 0, 0, cb, 0}; \
       ASN1_SEQUENCE(tname)

#define ASN1_SEQUENCE(tname) \
       static const ASN1_TEMPLATE tname##_seq_tt[]



#define ASN1_SEQUENCE_END_ref(stname, tname) \
       ;\
       ASN1_ITEM_start(tname) \
               ASN1_ITYPE_SEQUENCE,\
               V_ASN1_SEQUENCE,\
               tname##_seq_tt,\
               sizeof(tname##_seq_tt) / sizeof(ASN1_TEMPLATE),\
               &tname##_aux,\
               sizeof(stname),\
               #stname \
       ASN1_ITEM_end(tname)

#define ASN1_ITEM_start(itname) \
       const ASN1_ITEM * itname##_it(void) \
       { \
               static const ASN1_ITEM local_it = { \

#define ASN1_SEQUENCE_END_cb(stname, tname) ASN1_SEQUENCE_END_ref(stname, tname) Here we have your DHparams_it... With some (probably considerable) more effort you can do what the preprocessor does and manually find out which function will be compiled. There are probably ways to call gcc which will give you the output of the preprocessor, maybe the gcc manpage can help.

thanks

[...]

Does anyone know how to find the body part of function i2d_DHparams()? I can only find the definition part of this function

The macro is defined in crypto/asn1/asn1t.h.

Hope it helps,
Ted
;)

I think it is created by the macro IMPLEMENT_ASN1_ENCODE_FUNCTIONS_const_fname in file crypto/dh/dh_asn1.c.

Hope it helps.
Ted
;)

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