-<!-- $Id: odr.xml,v 1.12 2004-03-19 21:12:13 adam Exp $ -->
<chapter id="odr"><title>The ODR Module</title>
-
+
<sect1 id="odr.introduction"><title>Introduction</title>
<para>
</sect1>
<sect1 id="odr.use"><title>Using ODR</title>
- <sect2><title>ODR Streams</title>
+ <sect2 id="odr.streams"><title>ODR Streams</title>
<para>
Conceptually, the ODR stream is the source of encoded data in the
</para>
</sect2>
- <sect2><title id="memory">Memory Management</title>
+ <sect2 id="odr.memory.management"><title id="memory">Memory Management</title>
<para>
Two forms of memory management take place in the &odr; system. The first
</para>
<synopsis>
- void *odr_malloc(ODR o, int size);
+ void *odr_malloc(ODR o, size_t size);
</synopsis>
<para>
</para>
<synopsis>
- void odr_reset(ODR o, int size);
+ void odr_reset(ODR o);
</synopsis>
<para>
</para>
<synopsis>
- int odr_total(ODR o);
+ size_t odr_total(ODR o);
</synopsis>
<para>
</para>
</sect2>
- <sect2><title>Encoding and Decoding Data</title>
+ <sect2 id="odr.encoding.and.decoding"><title>Encoding and Decoding Data</title>
<para>
When encoding data, the ODR stream will write the encoded octet string
data you wish to decode (eg, <function>odr_integer()</function> odr
<function>z_APDU()</function>).
</para>
-
- <example><title>Encoding and decoding functions</title>
+
+ <example id="example.odr.encoding.and.decoding.functions">
+ <title>Encoding and decoding functions</title>
<synopsis>
- int odr_integer(ODR o, int **p, int optional, const char *name);
-
+ int odr_integer(ODR o, Odr_int **p, int optional, const char *name);
+
int z_APDU(ODR o, Z_APDU **p, int optional, const char *name);
</synopsis>
</example>
<function>free(2)</function> to release the memory.
You can decode several data elements (by repeated calls to
<function>odr_setbuf()</function> and your decoding function), and
- new memory will be allocated each time. When you do call
+ new memory will be allocated each time. When you do call
<function>odr_reset()</function>, everything decoded since the
last call to <function>odr_reset()</function> will be released.
</para>
- <example><title>Encoding and decoding of an integer</title>
+ <example id="example.odr.encoding.of.integer">
+ <title>Encoding and decoding of an integer</title>
<para>
The use of the double indirection can be a little confusing at first
(its purpose will become clear later on, hopefully),
informative operation.
</para>
<programlisting><![CDATA[
-void do_nothing_useful(int value)
+void do_nothing_useful(Odr_int value)
{
ODR encode, decode;
- int *valp, *resvalp;
+ Odr_int *valp, *resvalp;
char *bufferp;
int len;
-
+
/* allocate streams */
if (!(encode = odr_createmem(ODR_ENCODE)))
return;
if (!(decode = odr_createmem(ODR_DECODE)))
return;
- valp = &value;
- if (odr_integer(encode, &valp, 0, 0) == 0)
+ valp = &value;
+ if (odr_integer(encode, &valp, 0, 0) == 0)
{
printf("encoding went bad\n");
return;
}
- bufferp = odr_getbuf(encode, &len);
- printf("length of encoded data is %d\n", len);
+ bufferp = odr_getbuf(encode, &len, 0);
+ printf("length of encoded data is %d\n", len);
/* now let's decode the thing again */
- odr_setbuf(decode, bufferp, len);
- if (odr_integer(decode, &resvalp, 0, 0) == 0)
+ odr_setbuf(decode, bufferp, len, 0);
+ if (odr_integer(decode, &resvalp, 0, 0) == 0)
{
printf("decoding went bad\n");
return;
}
- printf("the value is %d\n", *resvalp);
+ /* ODR_INT_PRINTF format for printf (such as %d) */
+ printf("the value is " ODR_INT_PRINTF "\n", *resvalp);
/* clean up */
odr_destroy(encode);
program, so the overhead is quite manageable.
</para>
</example>
-
+
</sect2>
- <sect2><title>Diagnostics</title>
+ <sect2 id="odr.printing"><title>Printing</title>
+ <para>
+ When an ODR stream is created of type <literal>ODR_PRINT</literal>
+ the ODR module will print the contents of a PDU in a readable format.
+ By default output is written to the <literal>stderr</literal> stream.
+ This behavior can be changed, however, by calling the function
+ <synopsis>
+ odr_setprint(ODR o, FILE *file);
+ </synopsis>
+ before encoders or decoders are being invoked.
+ It is also possible to direct the output to a buffer (of indeed
+ another file), by using the more generic mechanism:
+ <synopsis>
+ void odr_set_stream(ODR o, void *handle,
+ void (*stream_write)(ODR o, void *handle, int type,
+ const char *buf, int len),
+ void (*stream_close)(void *handle));
+ </synopsis>
+ Here the user provides an opaque handle and two handlers,
+ <replaceable>stream_write</replaceable> for writing,
+ and <replaceable>stream_close</replaceable> which is supposed
+ to close/free resources associated with handle.
+ The <replaceable>stream_close</replaceable> handler is optional and
+ if NULL for the function is provided, it will not be invoked.
+ The <replaceable>stream_write</replaceable> takes the ODR handle
+ as parameter, the user defined handle, a type
+ <literal>ODR_OCTETSTRING</literal>, <literal>ODR_VISIBLESTRING</literal>
+ which indicates the type of contents is being written.
+ </para>
+ <para>
+ Another utility useful for diagnostics (error handling) or as
+ part of the printing facilities is:
+ <synopsis>
+ const char **odr_get_element_path(ODR o);
+ </synopsis>
+ which returns a list of current elements that ODR deals with at the
+ moment. For the returned array, say <literal>ar</literal>,
+ <literal>ar[0]</literal> is the top level element,
+ <literal>ar[n]</literal> is the last. The last element has the
+ property that <literal>ar[n+1] == NULL</literal>.
+ </para>
+ <example id="example.odr.element.path.record">
+ <title>Element Path for record</title>
+ <para>
+ For a database record part of a PresentResponse the
+ array returned by <function>odr_get_element</function>
+ is <literal>presentResponse</literal>, <literal>databaseOrSurDiagnostics</literal>, <literal>?</literal>, <literal>record</literal>, <literal>?</literal>, <literal>databaseRecord</literal> . The question mark appears due to
+ unnamed constructions.
+ </para>
+ </example>
+ </sect2>
+ <sect2 id="odr.diagnostics"><title>Diagnostics</title>
<para>
The encoding/decoding functions all return 0 when an error occurs.
one of these constants:
</para>
- <table frame="top"><title>ODR Error codes</title>
+ <table frame="top" id="odr.error.codes">
+ <title>ODR Error codes</title>
<tgroup cols="2">
<thead>
<row>
</para>
<synopsis>
- char *odr_errlist[]
+ char *odr_errlist[]
</synopsis>
<para>
</para>
</sect2>
- <sect2><title>Summary and Synopsis</title>
+ <sect2 id="odr.summary.and.synopsis">
+ <title>Summary and Synopsis</title>
<synopsis>
- #include <odr.h>
+ #include <yaz/odr.h>
ODR odr_createmem(int direction);
void odr_reset(ODR o);
- char *odr_getbuf(ODR o, int *len);
+ char *odr_getbuf(ODR o, int *len, int *size);
- void odr_setbuf(ODR o, char *buf, int len);
+ void odr_setbuf(ODR o, char *buf, int len, int can_grow);
void *odr_malloc(ODR o, int size);
- ODR_MEM odr_extract_mem(ODR o);
-
- void odr_release_mem(ODR_MEM r);
+ NMEM odr_extract_mem(ODR o);
int odr_geterror(ODR o);
- void odr_perror(char *message);
+ void odr_perror(ODR o, const char *message);
extern char *odr_errlist[];
</synopsis>
<tip>
<para>
There is an ASN.1 tutorial available at
- <ulink url="http://asn1.elibel.tm.fr/en/introduction/">this site</ulink>.
- This site also has standards for ASN.1 (X.680) and BER (X.690)
- <ulink url="http://asn1.elibel.tm.fr/en/standards/">online</ulink>.
+ <ulink url="&url.asn.1.tutorial;">this site</ulink>.
+ This site also has standards for ASN.1 (X.680) and BER (X.690)
+ <ulink url="&url.asn.1.standards;">online</ulink>.
</para>
</tip>
-
+
<para>
The ODR interface is based loosely on that of the Sun Microsystems
XDR routines.
definition for a type once - and you have the functionality of encoding,
decoding (and pretty-printing) all in one unit.
The resulting C source code is quite compact, and is a pretty
- straightforward representation of the source ASN.1 specification.
+ straightforward representation of the source ASN.1 specification.
</para>
-
+
<para>
In many cases, the model of the XDR functions works quite well in this
role.
SEQUENCE members which don't exist in XDR.
</para>
- <sect2><title>The Primitive ASN.1 Types</title>
+ <sect2 id="odr.primitive.asn1.types">
+ <title>The Primitive ASN.1 Types</title>
<para>
ASN.1 defines a number of primitive types (many of which correspond
roughly to primitive types in structured programming languages, such as C).
</para>
- <sect3><title>INTEGER</title>
+ <sect3 id="odr.integer"><title>INTEGER</title>
<para>
The &odr; function for encoding or decoding (or printing) the ASN.1
</para>
<synopsis>
- int odr_integer(ODR o, int **p, int optional, const char *name);
+ int odr_integer(ODR o, Odr_int **p, int optional, const char *name);
</synopsis>
<para>
- (we don't allow values that can't be contained in a C integer.)
+ The <literal>Odr_int</literal> is just a simple integer.
</para>
-
+
<para>
This form is typical of the primitive &odr; functions. They are named
after the type of data that they encode or decode. They take an &odr;
similar manners:
</para>
</sect3>
- <sect3><title>BOOLEAN</title>
+ <sect3 id="odr.boolean"><title>BOOLEAN</title>
<synopsis>
-int odr_bool(ODR o, bool_t **p, int optional, const char *name);
+int odr_bool(ODR o, Odr_bool **p, int optional, const char *name);
</synopsis>
</sect3>
- <sect3><title>REAL</title>
+ <sect3 id="odr.real"><title>REAL</title>
<para>
Not defined.
</para>
</sect3>
- <sect3><title>NULL</title>
+ <sect3 id="odr.null"><title>NULL</title>
<synopsis>
-int odr_null(ODR o, bool_t **p, int optional, const char *name);
+int odr_null(ODR o, Odr_null **p, int optional, const char *name);
</synopsis>
<para>
</para>
</sect3>
- <sect3><title>OCTET STRING</title>
+ <sect3 id="odr.octet.string"><title>OCTET STRING</title>
<synopsis>
typedef struct odr_oct
{
unsigned char *buf;
int len;
- int size;
} Odr_oct;
int odr_octetstring(ODR o, Odr_oct **p, int optional,
<para>
The <literal>buf</literal> field should point to the character array
that holds the octetstring. The <literal>len</literal> field holds the
- actual length, while the <literal>size</literal> field gives the size
- of the allocated array (not of interest to you, in most cases).
+ actual length.
The character array need not be null terminated.
</para>
</synopsis>
</sect3>
- <sect3><title>BIT STRING</title>
+ <sect3 id="odr.bit.string"><title>BIT STRING</title>
<synopsis>
int odr_bitstring(ODR o, Odr_bitmask **p, int optional,
</para>
</sect3>
- <sect3><title>OBJECT IDENTIFIER</title>
+ <sect3 id="odr.object.identifier"><title>OBJECT IDENTIFIER</title>
<synopsis>
int odr_oid(ODR o, Odr_oid **p, int optional, const char *name);
<para>
The C OID representation is simply an array of integers, terminated by
the value -1 (the <literal>Odr_oid</literal> type is synonymous with
- the <literal>int</literal> type).
+ the <literal>short</literal> type).
We suggest that you use the OID database module (see
- <xref linkend="asn.oid"/>) to handle object identifiers
+ <xref linkend="tools.oid.database"/>) to handle object identifiers
in your application.
</para>
</sect3>
</sect2>
- <sect2 id="tag.prim"><title>Tagging Primitive Types</title>
+ <sect2 id="odr.tagging.primitive.types"><title>Tagging Primitive Types</title> <!-- tag.prim -->
<para>
The simplest way of tagging a type is to use the
- <function>odr_implicit_tag()</function> or
+ <function>odr_implicit_tag()</function> or
<function>odr_explicit_tag()</function> macros:
</para>
</para>
<screen>
- MyInt ::= [210] IMPLICIT INTEGER
+ MyInt ::= [210] IMPLICIT INTEGER
</screen>
<para>
</para>
<screen>
-int myInt(ODR o, int **p, int optional, const char *name)
+int myInt(ODR o, Odr_int **p, int optional, const char *name)
{
return odr_implicit_tag(o, odr_integer, p,
ODR_CONTEXT, 210, optional, name);
</para>
</sect2>
- <sect2><title>Constructed Types</title>
+ <sect2 id="odr.constructed.types"><title>Constructed Types</title>
<para>
Constructed types are created by combining primitive types. The
<screen>
typedef struct MySequence
{
- int *intval;
- bool_t *boolval;
+ Odr_int *intval;
+ Odr_bool *boolval;
} MySequence;
-
+
int mySequence(ODR o, MySequence **p, int optional, const char *name)
{
if (odr_sequence_begin(o, p, sizeof(**p), name) == 0)
</para>
</sect2>
- <sect2><title>Tagging Constructed Types</title>
+ <sect2 id="odr.tagging.constructed.types">
+ <title>Tagging Constructed Types</title>
<note>
<para>
- See <xref linkend="tag.prim"/> for information on how to tag
+ See <xref linkend="odr.tagging.primitive.types"/> for information on how to tag
the primitive types, as well as types that are already defined.
</para>
</note>
- <sect3><title>Implicit Tagging</title>
+ <sect3 id="odr.implicit.tagging">
+ <title>Implicit Tagging</title>
<para>
Assume the type above had been defined as
</para>
<screen>
-MySequence ::= [10] IMPLICIT SEQUENCE {
+MySequence ::= [10] IMPLICIT SEQUENCE {
intval INTEGER,
boolval BOOLEAN OPTIONAL
}
</para>
</sect3>
- <sect3><title>Explicit Tagging</title>
+ <sect3 id="odr.explicit.tagging"><title>Explicit Tagging</title>
<para>
Explicit tagging of constructed types is a little more complicated,
</para>
<screen>
-MySequence ::= [10] IMPLICIT SEQUENCE {
+MySequence ::= [10] IMPLICIT SEQUENCE {
intval INTEGER,
boolval BOOLEAN OPTIONAL
}
</sect3>
</sect2>
- <sect2><title>SEQUENCE OF</title>
+ <sect2 id="odr.sequence.of"><title>SEQUENCE OF</title>
<para>
To handle sequences (arrays) of a specific type, the function
typedef struct MyArray
{
int num_elements;
- int **elements;
+ Odr_int **elements;
} MyArray;
</screen>
</screen>
</sect2>
- <sect2><title>CHOICE Types</title>
+ <sect2 id="odr.choice.types"><title>CHOICE Types</title>
<para>
The choice type is used fairly often in some ASN.1 definitions, so
</para>
<synopsis>
-int odr_choice(ODR o, Odr_arm arm[], void *p, void *whichp,
+int odr_choice(ODR o, Odr_arm arm[], void *p, void *whichp,
const char *name);
</synopsis>
<varlistentry><term>which</term>
<listitem><para>The value of the discriminator that corresponds to
- this CHOICE element. Typically, it will be a #defined constant, or
+ this CHOICE element. Typically, it will be a #defined constant, or
an enum member.</para></listitem>
</varlistentry>
<screen>
MyChoice ::= CHOICE {
untagged INTEGER,
- tagged [99] IMPLICIT INTEGER,
+ tagged [99] IMPLICIT INTEGER,
other BOOLEAN
}
</screen>
} which;
union
{
- int *untagged;
- int *tagged;
- bool_t *other;
+ Odr_int *untagged;
+ Odr_int *tagged;
+ Odr_bool *other;
} u;
};
</screen>
<screen>
int myChoice(ODR o, MyChoice **p, int optional, const char *name)
{
- static Odr_arm arm[] =
+ static Odr_arm arm[] =
{
{-1, -1, -1, MyChoice_untagged, odr_integer, "untagged"},
{ODR_IMPLICIT, ODR_CONTEXT, 99, MyChoice_tagged, odr_integer,
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