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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" ASN1_EXTERN_FUNCS, ASN1_ex_d2i, ASN1_ex_d2i_ex, ASN1_ex_i2d, ASN1_ex_new_func, ASN1_ex_new_ex_func, ASN1_ex_free_func, ASN1_ex_print_func, IMPLEMENT_EXTERN_ASN1 \&\- ASN.1 external function support .SH "LIBRARY" libcrypto, -lcrypto .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include \& \& typedef int ASN1_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len, \& const ASN1_ITEM *it, int tag, int aclass, char opt, \& ASN1_TLC *ctx); \& typedef int ASN1_ex_d2i_ex(ASN1_VALUE **pval, const unsigned char **in, long len, \& const ASN1_ITEM *it, int tag, int aclass, char opt, \& ASN1_TLC *ctx, OSSL_LIB_CTX *libctx, \& const char *propq); \& typedef int ASN1_ex_i2d(const ASN1_VALUE **pval, unsigned char **out, \& const ASN1_ITEM *it, int tag, int aclass); \& typedef int ASN1_ex_new_func(ASN1_VALUE **pval, const ASN1_ITEM *it); \& typedef int ASN1_ex_new_ex_func(ASN1_VALUE **pval, const ASN1_ITEM *it, \& OSSL_LIB_CTX *libctx, const char *propq); \& typedef void ASN1_ex_free_func(ASN1_VALUE **pval, const ASN1_ITEM *it); \& typedef int ASN1_ex_print_func(BIO *out, const ASN1_VALUE **pval, \& int indent, const char *fname, \& const ASN1_PCTX *pctx); \& \& struct ASN1_EXTERN_FUNCS_st { \& void *app_data; \& ASN1_ex_new_func *asn1_ex_new; \& ASN1_ex_free_func *asn1_ex_free; \& ASN1_ex_free_func *asn1_ex_clear; \& ASN1_ex_d2i *asn1_ex_d2i; \& ASN1_ex_i2d *asn1_ex_i2d; \& ASN1_ex_print_func *asn1_ex_print; \& ASN1_ex_new_ex_func *asn1_ex_new_ex; \& ASN1_ex_d2i_ex *asn1_ex_d2i_ex; \& }; \& typedef struct ASN1_EXTERN_FUNCS_st ASN1_EXTERN_FUNCS; \& \& #define IMPLEMENT_EXTERN_ASN1(sname, tag, fptrs) .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\s-1ASN.1\s0 data structures templates are typically defined in OpenSSL using a series of macros such as \s-1\fBASN1_SEQUENCE\s0()\fR, \s-1\fBASN1_SEQUENCE_END\s0()\fR and so on. Instead templates can also be defined based entirely on external functions. These external functions are called to perform operations such as creating a new \&\fB\s-1ASN1_VALUE\s0\fR or converting an \fB\s-1ASN1_VALUE\s0\fR to or from \s-1DER\s0 encoding. .PP The macro \s-1\fBIMPLEMENT_EXTERN_ASN1\s0()\fR can be used to create such an externally defined structure. The name of the structure should be supplied in the \fIsname\fR parameter. The tag for the structure (e.g. typically \fBV_ASN1_SEQUENCE\fR) should be supplied in the \fItag\fR parameter. Finally a pointer to an \&\fB\s-1ASN1_EXTERN_FUNCS\s0\fR structure should be supplied in the \fIfptrs\fR parameter. .PP The \fB\s-1ASN1_EXTERN_FUNCS\s0\fR structure has the following entries. .IP "\fIapp_data\fR" 4 .IX Item "app_data" A pointer to arbitrary application specific data. .IP "\fIasn1_ex_new\fR" 4 .IX Item "asn1_ex_new" A \*(L"new\*(R" function responsible for constructing a new \fB\s-1ASN1_VALUE\s0\fR object. The newly constructed value should be stored in \fI*pval\fR. The \fIit\fR parameter is a pointer to the \fB\s-1ASN1_ITEM\s0\fR template object created via the \&\s-1\fBIMPLEMENT_EXTERN_ASN1\s0()\fR macro. .Sp Returns a positive value on success or 0 on error. .IP "\fIasn1_ex_free\fR" 4 .IX Item "asn1_ex_free" A \*(L"free\*(R" function responsible for freeing the \fB\s-1ASN1_VALUE\s0\fR passed in \fI*pval\fR that was previously allocated via a \*(L"new\*(R" function. The \fIit\fR parameter is a pointer to the \fB\s-1ASN1_ITEM\s0\fR template object created via the \&\s-1\fBIMPLEMENT_EXTERN_ASN1\s0()\fR macro. .IP "\fIasn1_ex_clear\fR" 4 .IX Item "asn1_ex_clear" A \*(L"clear\*(R" function responsible for clearing any data in the \fB\s-1ASN1_VALUE\s0\fR passed in \fI*pval\fR and making it suitable for reuse. The \fIit\fR parameter is a pointer to the \fB\s-1ASN1_ITEM\s0\fR template object created via the \s-1\fBIMPLEMENT_EXTERN_ASN1\s0()\fR macro. .IP "\fIasn1_ex_d2i\fR" 4 .IX Item "asn1_ex_d2i" A \*(L"d2i\*(R" function responsible for converting \s-1DER\s0 data with the tag \fItag\fR and class \fIclass\fR into an \fB\s-1ASN1_VALUE\s0\fR. If \fI*pval\fR is non-NULL then the \&\fB\s-1ASN_VALUE\s0\fR it points to should be reused. Otherwise a new \fB\s-1ASN1_VALUE\s0\fR should be allocated and stored in \fI*pval\fR. \fI*in\fR points to the \s-1DER\s0 data to be decoded and \fIlen\fR is the length of that data. After decoding \fI*in\fR should be updated to point at the next byte after the decoded data. If the \fB\s-1ASN1_VALUE\s0\fR is considered optional in this context then \fIopt\fR will be nonzero. Otherwise it will be zero. The \fIit\fR parameter is a pointer to the \fB\s-1ASN1_ITEM\s0\fR template object created via the \s-1\fBIMPLEMENT_EXTERN_ASN1\s0()\fR macro. A pointer to the current \&\fB\s-1ASN1_TLC\s0\fR context (which may be required for other \s-1ASN1\s0 function calls) is passed in the \fIctx\fR parameter. .Sp The \fIasn1_ex_d2i\fR entry may be \s-1NULL\s0 if \fIasn1_ex_d2i_ex\fR has been specified instead. .Sp Returns <= 0 on error or a positive value on success. .IP "\fIasn1_ex_i2d\fR" 4 .IX Item "asn1_ex_i2d" An \*(L"i2d\*(R" function responsible for converting an \fB\s-1ASN1_VALUE\s0\fR into \s-1DER\s0 encoding. On entry \fI*pval\fR will contain the \fB\s-1ASN1_VALUE\s0\fR to be encoded. If default tagging is to be used then \fItag\fR will be \-1 on entry. Otherwise if implicit tagging should be used then \fItag\fR and \fIaclass\fR will be the tag and associated class. .Sp If \fIout\fR is not \s-1NULL\s0 then this function should write the \s-1DER\s0 encoded data to the buffer in \fI*out\fR, and then increment \fI*out\fR to point to immediately after the data just written. .Sp If \fIout\fR is \s-1NULL\s0 then no data should be written but the length calculated and returned as if it were. .Sp The \fIasn1_ex_i2d\fR entry may be \s-1NULL\s0 if \fIasn1_ex_i2d_ex\fR has been specified instead. .Sp The return value should be negative if a fatal error occurred, or 0 if a non-fatal error occurred. Otherwise it should return the length of the encoded data. .IP "\fIasn1_ex_print\fR" 4 .IX Item "asn1_ex_print" A \*(L"print\*(R" function. \fIout\fR is the \s-1BIO\s0 to print the output to. \fI*pval\fR is the \&\fB\s-1ASN1_VALUE\s0\fR to be printed. \fIindent\fR is the number of spaces of indenting to be printed before any data is printed. \fIfname\fR is currently unused and is always "". \fIpctx\fR is a pointer to the \fB\s-1ASN1_PCTX\s0\fR for the print operation. .Sp Returns 0 on error or a positive value on success. If the return value is 2 then an additional newline will be printed after the data printed by this function. .IP "\fIasn1_ex_new_ex\fR" 4 .IX Item "asn1_ex_new_ex" This is the same as \fIasn1_ex_new\fR except that it is additionally passed the \&\s-1OSSL_LIB_CTX\s0 to be used in \fIlibctx\fR and any property query string to be used for algorithm fetching in the \fIpropq\fR parameter. See \&\*(L"\s-1ALGORITHM FETCHING\*(R"\s0 in \fBcrypto\fR\|(7) for further details. If \fIasn1_ex_new_ex\fR is non \s-1NULL,\s0 then it will always be called in preference to \fIasn1_ex_new\fR. .IP "\fIasn1_ex_d2i_ex\fR" 4 .IX Item "asn1_ex_d2i_ex" This is the same as \fIasn1_ex_d2i\fR except that it is additionally passed the \&\s-1OSSL_LIB_CTX\s0 to be used in \fIlibctx\fR and any property query string to be used for algorithm fetching in the \fIpropq\fR parameter. See \&\*(L"\s-1ALGORITHM FETCHING\*(R"\s0 in \fBcrypto\fR\|(7) for further details. If \fIasn1_ex_d2i_ex\fR is non \s-1NULL,\s0 then it will always be called in preference to \fIasn1_ex_d2i\fR. .SH "RETURN VALUES" .IX Header "RETURN VALUES" Return values for the various callbacks are as described above. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBASN1_item_new_ex\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" The \fIasn1_ex_new_ex\fR and \fIasn1_ex_d2i_ex\fR callbacks were added in OpenSSL 3.0. .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2021 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at .