Param builder: make the OSSL_PARAM_BLD APIs public.

The catalyst for this is the difficult of passing BNs through the other
OSSL_PARAM APIs.

Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/11390)

1 files changed, 197 insertions, 0 deletions

diff --git a/doc/man3/OSSL_PARAM_BLD_init.pod b/doc/man3/OSSL_PARAM_BLD_init.pod
new file mode 100644
index 0000000000..0b61ece8bc
--- /dev/null
+++ b/doc/man3/OSSL_PARAM_BLD_init.pod
@@ -0,0 +1,197 @@
+=pod
+
+=head1 NAME
+
+OSSL_PARAM_BLD_init, OSSL_PARAM_BLD_to_param,
+OSSL_PARAM_BLD_free, OSSL_PARAM_BLD_push_int, OSSL_PARAM_BLD_push_uint,
+OSSL_PARAM_BLD_push_long, OSSL_PARAM_BLD_push_ulong,
+OSSL_PARAM_BLD_push_int32, OSSL_PARAM_BLD_push_uint32,
+OSSL_PARAM_BLD_push_int64, OSSL_PARAM_BLD_push_uint64,
+OSSL_PARAM_BLD_push_size_t, OSSL_PARAM_BLD_push_double,
+OSSL_PARAM_BLD_push_BN, OSSL_PARAM_BLD_push_BN_pad,
+OSSL_PARAM_BLD_push_utf8_string, OSSL_PARAM_BLD_push_utf8_ptr,
+OSSL_PARAM_BLD_push_octet_string, OSSL_PARAM_BLD_push_octet_ptr
+- functions to assist in the creation of OSSL_PARAM arrays
+
+=head1 SYNOPSIS
+
+=for openssl generic
+
+ #include "openssl/param_build.h"
+
+ #define OSSL_PARAM_BLD_MAX 10
+ typedef struct { ... } OSSL_PARAM_BLD;
+
+ void OSSL_PARAM_BLD_init(OSSL_PARAM_BLD *bld);
+ OSSL_PARAM *OSSL_PARAM_BLD_to_param(OSSL_PARAM_BLD *bld);
+ void OSSL_PARAM_BLD_free(OSSL_PARAM *params);
+
+ int OSSL_PARAM_BLD_push_TYPE(OSSL_PARAM_BLD *bld, const char *key, TYPE val);
+
+ int OSSL_PARAM_BLD_push_BN(OSSL_PARAM_BLD *bld, const char *key,
+                            const BIGNUM *bn);
+ int OSSL_PARAM_BLD_push_BN_pad(OSSL_PARAM_BLD *bld, const char *key,
+                                const BIGNUM *bn, size_t sz);
+
+ int OSSL_PARAM_BLD_push_utf8_string(OSSL_PARAM_BLD *bld, const char *key,
+                                     const char *buf, size_t bsize);
+ int OSSL_PARAM_BLD_push_utf8_ptr(OSSL_PARAM_BLD *bld, const char *key,
+                                  char *buf, size_t bsize);
+ int OSSL_PARAM_BLD_push_octet_string(OSSL_PARAM_BLD *bld, const char *key,
+                                      const void *buf, size_t bsize);
+ int OSSL_PARAM_BLD_push_octet_ptr(OSSL_PARAM_BLD *bld, const char *key,
+                                   void *buf, size_t bsize);
+
+
+=head1 DESCRIPTION
+
+A collection of utility functions that simplify the creation of OSSL_PARAM
+arrays.  The B<I<TYPE>> names are as per L<OSSL_PARAM_int(3)>.
+
+OSSL_PARAM_BLD_init() initialises the OSSL_PARAM_BLD structure so that values
+can be added.
+Any existing values are cleared.
+
+OSSL_PARAM_BLD_to_param() converts a built up OSSL_PARAM_BLD structure
+I<bld> into an allocated OSSL_PARAM array.
+The OSSL_PARAM array and all associated storage must be freed by calling
+OSSL_PARAM_BLD_free() with the functions return value.
+
+OSSL_PARAM_BLD_free() deallocates the memory allocated by
+OSSL_PARAM_BLD_to_param().
+
+=begin comment
+
+POD is pretty good at recognising function names and making them appropriately
+bold...  however, when part of the function name is variable, we have to help
+the processor along
+
+=end comment
+
+B<OSSL_PARAM_BLD_push_I<TYPE>>() are a series of functions which will create
+OSSL_PARAM objects of the specified size and correct type for the I<val>
+argument.
+I<val> is stored by value and an expression or auto variable can be used.
+
+OSSL_PARAM_BLD_push_BN() is a function that will create an OSSL_PARAM object
+that holds the specified BIGNUM I<bn>.
+If I<bn> is marked as being securely allocated, its OSSL_PARAM representation
+will also be securely allocated.
+The I<bn> argument is stored by reference and the underlying BIGNUM object
+must exist until after OSSL_PARAM_BLD_to_param() has been called.
+
+OSSL_PARAM_BLD_push_BN_pad() is a function that will create an OSSL_PARAM object
+that holds the specified BIGNUM I<bn>.
+The object will be padded to occupy exactly I<sz> bytes, if insufficient space
+is specified an error results.
+If I<bn> is marked as being securely allocated, its OSSL_PARAM representation
+will also be securely allocated.
+The I<bn> argument is stored by reference and the underlying BIGNUM object
+must exist until after OSSL_PARAM_BLD_to_param() has been called.
+
+OSSL_PARAM_BLD_push_utf8_string() is a function that will create an OSSL_PARAM
+object that references the UTF8 string specified by I<buf>.
+If the length of the string, I<bsize>, is zero then it will be calculated.
+The string that I<buf> points to is stored by reference and must remain in
+scope until after OSSL_PARAM_BLD_to_param() has been called.
+
+OSSL_PARAM_BLD_push_octet_string() is a function that will create an OSSL_PARAM
+object that references the octet string specified by I<buf> and <bsize>.
+The memory that I<buf> points to is stored by reference and must remain in
+scope until after OSSL_PARAM_BLD_to_param() has been called.
+
+OSSL_PARAM_BLD_push_utf8_ptr() is a function that will create an OSSL_PARAM
+object that references the UTF8 string specified by I<buf>.
+If the length of the string, I<bsize>, is zero then it will be calculated.
+The string I<buf> points to is stored by reference and must remain in
+scope until the OSSL_PARAM array is freed.
+
+OSSL_PARAM_BLD_push_octet_ptr() is a function that will create an OSSL_PARAM
+object that references the octet string specified by I<buf>.
+The memory I<buf> points to is stored by reference and must remain in
+scope until the OSSL_PARAM array is freed.
+
+=head1 RETURN VALUES
+
+OSSL_PARAM_BLD_to_param() returns the allocated OSSL_PARAM array, or NULL
+on error.
+
+All of the OSSL_PARAM_BLD_push_TYPE functions return 1 on success and 0
+on error.
+
+=head1 NOTES
+
+The constant B<OSSL_PARAM_BLD_MAX> specifies the maximum number of parameters
+that can be added.
+Exceeding this will result in the push functions returning errors.
+The define used for this will always be at least 10 but otherwise no assumption
+should be made about it's specific value.
+
+The structure B<OSSL_PARAM_BLD> should be considered opaque and subject to
+change between versions.
+
+=head1 EXAMPLES
+
+Both examples creating an OSSL_PARAM array that contains an RSA key.
+For both, the predefined key variables are:
+
+    BIGNUM *p, *q;  /* both prime */
+    BIGNUM *n;      /* = p * q */
+    unsigned int e; /* exponent, usually 65537 */
+    BIGNUM *d;      /* e^-1 */
+
+=head2 Example 1
+
+This example shows how to create an OSSL_PARAM array that contains an RSA
+private key.
+
+    OSSL_PARAM_BLD bld;
+    OSSL_PARAM *params;
+
+    OSSL_PARAM_BLD_init(&bld, &secure);
+    if (!OSSL_PARAM_BLD_push_BN(&bld, "p", p)
+        || !OSSL_PARAM_BLD_push_BN(&bld, "q", q)
+        || !OSSL_PARAM_BLD_push_uint(&bld, "e", e)
+        || !OSSL_PARAM_BLD_push_BN(&bld, "n", n)
+        || !OSSL_PARAM_BLD_push_BN(&bld, "d", d)
+        || (params = OSSL_PARAM_BLD_to_param(&bld)) == NULL)
+        goto err;
+    /* Use params */
+    ...
+    OSSL_PARAM_BLD_free(params);
+
+=head2 Example 2
+
+This example shows how to create an OSSL_PARAM array that contains an RSA
+public key.
+
+    OSSL_PARAM_BLD bld;
+    OSSL_PARAM *params;
+
+    OSSL_PARAM_BLD_init(&bld, &secure);
+    if (!OSSL_PARAM_BLD_push_BN(&bld, "n", n)
+        || !OSSL_PARAM_BLD_push_BN(&bld, "d", d)
+        || (params = OSSL_PARAM_BLD_to_param(&bld)) == NULL)
+        goto err;
+    /* Use params */
+    ...
+    OSSL_PARAM_BLD_free(params);
+
+=head1 SEE ALSO
+
+L<OSSL_PARAM_int(3)>, L<OSSL_PARAM(3)>
+
+=head1 HISTORY
+
+The functions described here were all added in OpenSSL 3.0.
+
+=head1 COPYRIGHT
+
+Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the Apache License 2.0 (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
+
+=cut