ASN1_TYPE documentation.

Reviewed-by: Richard Levitte <levitte@openssl.org>

doc/crypto/ASN1_STRING_length.pod

@@ -48,7 +48,7 @@ such as B<V_ASN1_OCTET_STRING>.
 ASN1_STRING_to_UTF8() converts the string B<in> to UTF8 format, the
 converted data is allocated in a buffer in B<*out>. The length of
 B<out> is returned or a negative error code. The buffer B<*out>
-should be free using OPENSSL_free().
+should be freed using OPENSSL_free().
 
 =head1 NOTES
 

doc/crypto/ASN1_TYPE_get.pod

@@ -0,0 +1,70 @@
+=pod
+
+=head1 NAME
+
+ASN1_TYPE_get, ASN1_TYPE_set, ASN1_TYPE_set1, ASN1_TYPE_cmp - ASN1_TYPE utility
+functions
+
+=head1 SYNOPSIS
+
+ #include <openssl/asn1.h>
+
+ int ASN1_TYPE_get(ASN1_TYPE *a);
+ void ASN1_TYPE_set(ASN1_TYPE *a, int type, void *value);
+ int ASN1_TYPE_set1(ASN1_TYPE *a, int type, const void *value);
+ int ASN1_TYPE_cmp(const ASN1_TYPE *a, const ASN1_TYPE *b);
+
+=head1 DESCRIPTION
+
+These functions allow an ASN1_TYPE structure to be manipulated. The
+ASN1_TYPE structure can contain any ASN.1 type or constructed type
+such as a SEQUENCE: it is effectively equivalent to the ASN.1 ANY type.
+
+ASN1_TYPE_get() returns the type of B<a>.
+
+ASN1_TYPE_set() sets the value of B<a> to B<type> and B<value>. This
+function uses the pointer B<value> internally so it must B<not> be freed
+up after the call.
+
+ASN1_TYPE_set1() sets the value of B<a> to B<type> a copy of B<value>.
+
+ASN1_TYPE_cmp() compares ASN.1 types B<a> and B<b> and returns 0 if
+they are identical and non-zero otherwise.
+
+=head1 NOTES
+
+The type and meaning of the B<value> parameter for ASN1_TYPE_set() and
+ASN1_TYPE_set1() is determined by the B<type> parameter.
+If B<type> is V_ASN1_NULL B<value> is ignored. If B<type> is V_ASN1_BOOLEAN
+then the boolean is set to TRUE if B<value> is not NULL. If B<type> is
+V_ASN1_OBJECT then value is an ASN1_OBJECT structure. Otherwise B<type>
+is and ASN1_STRING structure. If B<type> corresponds to a primitive type
+(or a string type) then the contents of the ASN1_STRING contain the content
+octets of the type. If B<type> corresponds to a constructed type or
+a tagged type (V_ASN1_SEQUENCE, V_ASN1_SET or V_ASN1_OTHER) then the
+ASN1_STRING contains the entire ASN.1 encoding verbatim (including tag and
+length octets).
+
+ASN1_TYPE_cmp() may not return zero if two types are equivalent but have
+different encodings. For example the single content octet of the boolean TRUE
+value under BER can have any non-zero encoding but ASN1_TYPE_cmp() will
+only return zero if the values are the same.
+
+If either or both of the parameters passed to ASN1_TYPE_cmp() is NULL the
+return value is non-zero. Technically if both parameters are NULL the two
+types could be absent OPTIONAL fields and so should match, however passing
+NULL values could also indicate a programming error (for example an
+unparseable type which returns NULL) for types which do B<not> match. So
+applications should handle the case of two absent values separately.
+
+=head1 RETURN VALUES
+
+ASN1_TYPE_get() returns the type of the ASN1_TYPE argument.
+
+ASN1_TYPE_set() does not return a value.
+
+ASN1_TYPE_set1() returns 1 for sucess and 0 for failure.
+
+ASN1_TYPE_cmp() returns 0 if the types are identical and non-zero otherwise.
+
+=cut