Document the tracing functionality

=back

=head1 ENVIRONMENT

=over 4

=item B<OPENSSL_TRACE=>I<name,...>

Enable tracing output of OpenSSL library, by name.

This output will only make sense if you know OpenSSL internals well.

Also, it might not give you any output at all, depending on how

OpenSSL was built.

The value is a comma separated list of names, with the following

available:

=over 4

=item B<TRACE>

The tracing functionality.

=item B<TLS>

General SSL/TLS.

=item B<TLS_CIPHER>

SSL/TLS cipher.

=item B<ENGINE_CONF>

ENGINE configuration.

=item B<ENGINE_TABLE>

The function that is used by RSA, DSA (etc) code to select registered

ENGINEs, cache defaults and functional references (etc), will generate

debugging summaries.

=item B<ENGINE_REF_COUNT>

Reference counts in the ENGINE structure will be monitored with a line

of generated for each change.

=item B<PKCS5V2>

PKCS#5 v2 keygen.

=item B<PKCS12_KEYGEN>

PKCS#12 key generation.

=item B<PKCS12_DECRYPT>

PKCS#12 decryption.

=item B<X509V3_POLICY>

Generates the complete policy tree at various point during X.509 v3

policy evaluation.

=item B<BN_CTX>

BIGNUM context.

=back

=back

=head1 SEE ALSO

L<asn1parse(1)>, L<ca(1)>, L<ciphers(1)>, L<cms(1)>, L<config(5)>,

=pod

=head1 NAME

OSSL_trace_enabled, OSSL_trace_begin, OSSL_trace_end

- OpenSSL Tracing API

=head1 SYNOPSIS

 #include <openssl/trace.h>

 int OSSL_trace_enabled(int category);

 BIO *OSSL_trace_begin(int category);

 void OSSL_trace_end(int category, BIO *channel);

=head1 DESCRIPTION

The functions described here are mainly interesting for those who provide

OpenSSL functionality, either in OpenSSL itself or in engine modules

or similar.

If operational (see L</NOTES> below), these functions are used to

generate free text tracing output.

The tracing output is divided into types which are enabled

individually by the application.

The tracing types are described in detail in

L<OSSL_trace_set_callback(3)/Trace types>.

The fallback type C<OSSL_TRACE_CATEGORY_ANY> should I<not> be used

with the functions described here.

=head2 Functions

OSSL_trace_enabled() can be used to check if tracing for the given

C<category> is enabled.

OSSL_trace_begin() is used to starts a tracing section, and get the

channel for the given C<category> in form of a BIO.

This BIO can only be used for output.

OSSL_trace_end() is used to end a tracing section.

Using OSSL_trace_begin() and OSSL_trace_end() to wrap tracing sections

is I<mandatory>.

The result of trying to produce tracing output outside of such

sections is undefined.

=head2 Convenience Macros

There are a number of convenience macros defined, to make tracing

easy and consistent.

C<OSSL_TRACE_BEGIN(category)> and C<OSSL_TRACE_END(category)> reserve

the B<BIO> C<trc_out> and are used as follows to wrap a trace section:

 OSSL_TRACE_BEGIN(TLS) {

     BIO_fprintf(trc_out, ... );

 } OSSL_TRACE_END(TLS);

This will normally expands to:

 do {

     BIO *trc_out = OSSL_trace_begin(OSSL_TRACE_CATEGORY_TLS);

     if (trc_out != NULL) {

         ...

         BIO_fprintf(trc_out, ...);

     }

     OSSL_trace_end(OSSL_TRACE_CATEGORY_TLS, trc_out);

 } while (0);

C<OSSL_TRACE_CANCEL(category)> must be used before returning from or

jumping out of a trace section:

 OSSL_TRACE_BEGIN(TLS) {

     if (condition) {

         OSSL_TRACE_CANCEL(TLS);

         goto err;

     }

     BIO_fprintf(trc_out, ... );

 } OSSL_TRACE_END(TLS);

This will normally expand to:

 do {

     BIO *trc_out = OSSL_trace_begin(OSSL_TRACE_CATEGORY_TLS);

     if (trc_out != NULL) {

         if (condition) {

             OSSL_trace_end(OSSL_TRACE_CATEGORY_TLS, trc_out);

             goto err;

         }

         BIO_fprintf(trc_out, ... );

     }

     OSSL_trace_end(OSSL_TRACE_CATEGORY_TLS, trc_out);

 } while (0);

=head1 NOTES

It is advisable to always check that a trace type is enabled with

OSSL_trace_enabled() before generating any output, for example:

    if (OSSL_trace_enabled(OSSL_TRACE_CATEGORY_TLS)) {

        BIO *trace = OSSL_trace_begin(OSSL_TRACE_CATEGORY_TLS);

        BIO_printf(trace, "FOO %d\n", somevalue);

        BIO_dump(trace, somememory, somememory_l);

        OSSL_trace_end(OSSL_TRACE_CATEGORY_TLS, trace);

    }

=head2 Tracing disabled

The OpenSSL library may be built with tracing disabled, which makes

everything documented here inoperational.

When the library is built with tracing disabled:

=over 4

=item *

The macro C<OPENSSL_NO_TRACE> is defined in C<openssl/opensslconf.h>.

=item *

all functions are still present, bu OSSL_trace_enabled() will always

report the categories as disabled, and all other functions will do

nothing.

=item *

the convenience macros are defined to produce dead code.

For example, take this example from L</Convenience Macros> above:

 OSSL_TRACE_BEGIN(TLS) {

     if (condition) {

         OSSL_TRACE_CANCEL(TLS);

         goto err;

     }

     BIO_fprintf(trc_out, ... );

 } OSSL_TRACE_END(TLS);

When the tracing API isn't operational, that will expand to:

 do {

     BIO *trc_out = NULL;

     if (0) {

         if (condition) {

             ((void)0);

             goto err;

         }

         BIO_fprintf(trc_out, ... );

     }

 } while (0);

=back

=head1 RETURN VALUES

OSSL_trace_enabled() returns 1 if tracing for the given B<type> is

operational and enabled, otherwise 0.

OSSL_trace_begin() returns a C<BIO *> if the given B<type> is enabled,

otherwise C<NULL>.

=head1 HISTORY

The OpenSSL Tracing API was added ino OpenSSL 3.0.0.

=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

=pod

=head1 NAME

OSSL_trace_get_category_num, OSSL_trace_get_category_name

- OpenSSL tracing information functions

=head1 SYNOPSIS

 #include <openssl/trace.h>

 int OSSL_trace_get_category_num(const char *name);

 const char *OSSL_trace_get_category_name(int num);

=head1 DESCRIPTION

OSSL_trace_get_category_num() gives the category number corresponding

to the given C<name>.

OSSL_trace_get_category_name() gives the category name corresponding

to the given C<num>.

=head1 RETURN VALUES

OSSL_trace_get_category_num() returns the category number if the given

C<name> is a recognised category name, otherwise -1.

OSSL_trace_get_category_name() returns the category name if the given

C<num> is a recognised category number, otherwise NULL.

=head1 HISTORY

The OpenSSL Tracing API was added ino OpenSSL 3.0.0.

=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

=pod

=head1 NAME

OSSL_trace_set_channel, OSSL_trace_set_prefix, OSSL_trace_set_suffix,

OSSL_trace_set_callback, OSSL_trace_cb - Enabling trace output

=head1 SYNOPSIS

 #include <openssl/trace.h>

 typedef size_t (*OSSL_trace_cb)(const char *buf, size_t cnt,

                                 int category, int cmd, void *data);

 void OSSL_trace_set_channel(int category, BIO *bio);

 void OSSL_trace_set_prefix(int category, const char *prefix);

 void OSSL_trace_set_suffix(int category, const char *suffix);

 void OSSL_trace_set_callback(int category, OSSL_trace_cb cb, void  *data);

=head1 DESCRIPTION

If available (see L</NOTES> below), the application can request

internal trace output.

This output comes in form of free text for humans to read.

The trace output is divided into categories which can be

enabled individually.

They are enabled by giving them a channel in form of a BIO, or a

tracer callback, which is responsible for performing the actual

output.

=head2 Functions

OSSL_trace_set_channel() is used to enable the given trace C<category>

by giving it the B<BIO> C<bio>.

OSSL_trace_set_prefix() and OSSL_trace_set_suffix() can be used to add

an extra line for each channel, to be output before and after group of

tracing output.

What constitues an output group is decided by the code that produces

the output.

The lines given here are considered immutable; for more dynamic

tracing prefixes, consider setting a callback with

OSSL_trace_set_callback() instead.

OSSL_trace_set_callback() is used to enable the given trace

C<category> by giving it the tracer callback C<cb> with the associated

data C<data>, which will simply be passed through to C<cb> whenever

it's called.

This should be used when it's desirable to do form the trace output to

something suitable for application needs where a prefix and suffix

line aren't enough.

OSSL_trace_set_channel() and OSSL_trace_set_callback() are mutually

exclusive, calling one of them will clear whatever was set by the

previous call.

Calling OSSL_trace_set_channel() with C<NULL> for C<channel> or

OSSL_trace_set_callback() with C<NULL> for C<cb> disables tracing for

the given C<category>

=head2 Trace callback

The tracer callback must return a C<size_t>, which must be zero on

error and otherwise return the number of bytes that were output.

It receives a text buffer C<buf> with C<cnt> bytes of text, as well as

the C<category>, a control number C<cmd>, and the C<data> that was

passed to OSSL_trace_set_callback().

The possible control numbers are:

=over 4

=item C<OSSL_TRACE_CTRL_BEGIN>

The callback is called from OSSL_trace_begin(), which gives the

callback the possibility to output a dynamic starting line, or set a

prefix that should be output at the beginning of each line, or

something other.

=item C<OSSL_TRACE_CTRL_DURING>

The callback is called from any regular BIO output routine.

=item C<OSSL_TRACE_CTRL_END>

The callback is called from OSSL_trace_end(), which gives the callback

the possibility to output a dynamic ending line, or reset the line

prefix that was set with OSSL_TRACE_CTRL_BEGIN, or something other.

=back

=head2 Trace categories

The trace categories are simple numbers available through macros.

=over 4

=item C<OSSL_TRACE_CATEGORY_TRACE>

Traces the OpenSSL trace API itself.

More precisely, this will generate trace output any time a new

trace hook is set.

=item C<OSSL_TRACE_CATEGORY_INIT>

Traces OpenSSL library initialization and cleanup.

This needs special care, as OpenSSL will do automatic cleanup after

exit from C<main()>, and any tracing output done during this cleanup

will be lost if the tracing channel or callback were cleaned away

prematurely.

A suggestion is to make such cleanup part of a function that's

registered very early with L<atexit(3)>.

=item C<OSSL_TRACE_CATEGORY_TLS>

Traces the TLS/SSL protocoll.

=item C<OSSL_TRACE_CATEGORY_TLS_CIPHER>

Traces the ciphers used by the TLS/SSL protocoll.

=item C<OSSL_TRACE_CATEGORY_ENGINE_CONF>

Traces the ENGINE configuration.

=item C<OSSL_TRACE_CATEGORY_ENGINE_TABLE>

Traces the ENGINE algorithm table selection.

More precisely, engine_table_select(), the function that is used by

RSA, DSA (etc) code to select registered ENGINEs, cache defaults and

functional references (etc), will generate trace summaries.

=item C<OSSL_TRACE_CATEGORY_ENGINE_REF_COUNT>

Tracds the ENGINE reference counting.

More precisely, both reference counts in the ENGINE structure will be

monitored with a line of trace output generated for each change.

=item C<OSSL_TRACE_CATEGORY_PKCS5V2>

Traces PKCS#5 v2 key generation.

=item C<OSSL_TRACE_CATEGORY_PKCS12_KEYGEN>

Traces PKCS#12 key generation.

=item C<OSSL_TRACE_CATEGORY_PKCS12_DECRYPT>

Traces PKCS#12 decryption.

=item C<OSSL_TRACE_CATEGORY_X509V3_POLICY>

Traces X509v3 policy processing.

More precisely, this generates the complete policy tree at various

point during evaluation.

=item C<OSSL_TRACE_CATEGORY_BN_CTX>

Traces BIGNUM context operations.

=back

There is also C<OSSL_TRACE_CATEGORY_ANY>, which works as a fallback

and can be used to get I<all> trace output.

=head1 RETURN VALUES

OSSL_trace_set_channel(), OSSL_trace_set_prefix(),

OSSL_trace_set_suffix(), and OSSL_trace_set_callback() return 1 on

success, or 0 on failure.

=head1 EXAMPLES

In all examples below, we assume that the trace producing code is

this:

 int foo = 42;

 const char bar[] = { 0,  1,  2,  3,  4,  5,  6,  7,

                      8,  9, 10, 11, 12, 13, 14, 15 };

 OSSL_TRACE_BEGIN(TLS) {

     BIO_puts(trc_out, "foo: ");

     BIO_printf(trc_out, "%d\n", foo);

     BIO_dump(trc_out, bar, sizeof(bar));

 } OSSL_TRACE_END(TLS);

=head1 Simple example

An example with just a channel and constant prefix / suffix.

 int main(int argc, char *argv[])

 {

     BIO *err = BIO_new_fp(stderr, BIO_NOCLOSE | BIO_FP_TEXT);

     OSSL_trace_set_channel(OSSL_TRACE_CATEGORY_SSL, err);

     OSSL_trace_set_prefix(OSSL_TRACE_CATEGORY_SSL, "BEGIN TRACE[TLS]");

     OSSL_trace_set_suffix(OSSL_TRACE_CATEGORY_SSL, "END TRACE[TLS]");

     /* ... work ... */

 }

When the trace producing code above is performed, this will be output

on standard error:

 BEGIN TRACE[TLS]

 foo: 42

 0000 - 00 01 02 03 04 05 06 07-08 09 0a 0b 0c 0d 0e 0f   ................

 END TRACE[TLS]

=head2 Advanced example

This example uses the callback, and depends on pthreads functionality.

 static size_t cb(const char *buf, size_t cnt,

                 int category, int cmd, void *vdata)

 {

     BIO *bio = vdata;

     const char *label = NULL;

     switch (cmd) {

     case OSSL_TRACE_CTRL_BEGIN:

         label = "BEGIN";

         break;

     case OSSL_TRACE_CTRL_END:

         label = "END";

         break;

     }

     if (label != NULL) {

         union {

             pthread_t tid;

             unsigned long ltid;

         } tid;

         tid.tid = pthread_self();

         BIO_printf(bio, "%s TRACE[%s]:%lx\n",

                    label, OSSL_trace_get_category_name(category), tid.ltid);

     }

     return (size_t)BIO_puts(bio, buf);

 }

 int main(int argc, char *argv[])

 {

     BIO *err = BIO_new_fp(stderr, BIO_NOCLOSE | BIO_FP_TEXT);

     OSSL_trace_set_callback(OSSL_TRACE_CATEGORY_SSL, cb, err);

     /* ... work ... */

 }

The output is almost the same as for the simple example above.

 BEGIN TRACE[TLS]:7f9eb0193b80

 foo: 42

 0000 - 00 01 02 03 04 05 06 07-08 09 0a 0b 0c 0d 0e 0f   ................

 END TRACE[TLS]:7f9eb0193b80

=head1 NOTES

=head2 Tracing disabled

The OpenSSL library may be built with tracing disabled, which makes

everything documented here inoperational.

When the library is built with tracing disabled, the macro

C<OPENSSL_NO_TRACE> is defined in C<openssl/opensslconf.h> and all

functions described here are inoperational, i.e. will do nothing.

=head1 HISTORY

OSSL_trace_set_channel(), OSSL_trace_set_prefix(),

OSSL_trace_set_suffix(), and OSSL_trace_set_callback() were all added

in OpenSSL 3.0.0.

=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

OSSL_STORE_load_fn                      datatype

OSSL_STORE_open_fn                      datatype

OSSL_STORE_post_process_info_fn         datatype

OSSL_trace_cb                           datatype

PROFESSION_INFO                         datatype

PROFESSION_INFOS                        datatype

RAND_DRBG_cleanup_entropy_fn            datatype