=pod

=head1 NAME

OCSP_sendreq_new, OCSP_sendreq_nbio, OCSP_REQ_CTX_free,
OCSP_set_max_response_length, OCSP_REQ_CTX_add1_header,
OCSP_REQ_CTX_set1_req, OCSP_sendreq_bio - OCSP responder query functions

=head1 SYNOPSIS

 #include <openssl/ocsp.h>

 OCSP_REQ_CTX *OCSP_sendreq_new(BIO *io, const char *path, OCSP_REQUEST *req,
                                int maxline);

 int OCSP_sendreq_nbio(OCSP_RESPONSE **presp, OCSP_REQ_CTX *rctx);

 void OCSP_REQ_CTX_free(OCSP_REQ_CTX *rctx);

 void OCSP_set_max_response_length(OCSP_REQ_CTX *rctx, unsigned long len);

 int OCSP_REQ_CTX_add1_header(OCSP_REQ_CTX *rctx,
                              const char *name, const char *value);

 int OCSP_REQ_CTX_set1_req(OCSP_REQ_CTX *rctx, OCSP_REQUEST *req);

 OCSP_RESPONSE *OCSP_sendreq_bio(BIO *io, const char *path, OCSP_REQUEST *req,
                                 int maxline);

=head1 DESCRIPTION

The function OCSP_sendreq_new() returns an B<OCSP_CTX> structure using the
responder B<io>, the URL path B<path>, the OCSP request B<req> and with a
response header maximum line length of B<maxline>. If B<maxline> is zero a
default value of 4k is used. The OCSP request B<req> may be set to B<NULL>
and provided later if required.

OCSP_sendreq_nbio() performs non-blocking I/O on the OCSP request context
B<rctx>. When the operation is complete it returns the response in B<*presp>.

OCSP_REQ_CTX_free() frees up the OCSP context B<rctx>.

OCSP_set_max_response_length() sets the maximum response length for B<rctx>
to B<len>. If the response exceeds this length an error occurs. If not
set a default value of 100k is used.

OCSP_REQ_CTX_add1_header() adds header B<name> with value B<value> to the
context B<rctx>. It can be called more than once to add multiple headers.
It B<MUST> be called before any calls to OCSP_sendreq_nbio(). The B<req>
parameter in the initial to OCSP_sendreq_new() call MUST be set to B<NULL> if
additional headers are set.

OCSP_REQ_CTX_set1_req() sets the OCSP request in B<rctx> to B<req>. This
function should be called after any calls to OCSP_REQ_CTX_add1_header().

OCSP_sendreq_bio() performs an OCSP request using the responder B<io>, the URL
path B<path>, the OCSP request B<req> and with a response header maximum line
length of B<maxline>. If B<maxline> is zero a default value of 4k is used.

=head1 RETURN VALUES

OCSP_sendreq_new() returns a valid B<OCSP_REQ_CTX> structure or B<NULL> if
an error occurred.

OCSP_sendreq_nbio() returns B<1> if the operation was completed successfully,
B<-1> if the operation should be retried and B<0> if an error occurred.

OCSP_REQ_CTX_add1_header() and OCSP_REQ_CTX_set1_req() return B<1> for success
and B<0> for failure.

OCSP_sendreq_bio() returns the B<OCSP_RESPONSE> structure sent by the
responder or B<NULL> if an error occurred.

OCSP_REQ_CTX_free() and OCSP_set_max_response_length() do not return values.

=head1 NOTES

These functions only perform a minimal HTTP query to a responder. If an
application wishes to support more advanced features it should use an
alternative more complete HTTP library.

Currently only HTTP POST queries to responders are supported.

The arguments to OCSP_sendreq_new() correspond to the components of the URL.
For example if the responder URL is B<http://ocsp.com/ocspreq> the BIO
B<io> should be connected to host B<ocsp.com> on port 80 and B<path>
should be set to B<"/ocspreq">

The headers added with OCSP_REQ_CTX_add1_header() are of the form
"B<name>: B<value>" or just "B<name>" if B<value> is B<NULL>. So to add
a Host header for B<ocsp.com> you would call:

 OCSP_REQ_CTX_add1_header(ctx, "Host", "ocsp.com");

If OCSP_sendreq_nbio() indicates an operation should be retried the
corresponding BIO can be examined to determine which operation (read or
write) should be retried and appropriate action taken (for example a select()
call on the underlying socket).

OCSP_sendreq_bio() does not support retries and so cannot handle non-blocking
I/O efficiently. It is retained for compatibility and its use in new
applications is not recommended.

=head1 SEE ALSO

L<crypto(7)>,
L<OCSP_cert_to_id(3)>,
L<OCSP_request_add1_nonce(3)>,
L<OCSP_REQUEST_new(3)>,
L<OCSP_resp_find_status(3)>,
L<OCSP_response_status(3)>

=head1 COPYRIGHT

Copyright 2015-2016 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
