7c3a7561b5
This commit adds the SSL_sendfile call, which allows KTLS sockets to transmit file using zero-copy semantics. Signed-off-by: Boris Pismenny <borisp@mellanox.com> Reviewed-by: Paul Dale <paul.dale@oracle.com> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/8727)
155 lines
6.2 KiB
Text
155 lines
6.2 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
SSL_write_ex, SSL_write, SSL_sendfile - write bytes to a TLS/SSL connection
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/ssl.h>
|
|
|
|
ossl_ssize_t SSL_sendfile(SSL *s, int fd, off_t offset, size_t size, int flags);
|
|
int SSL_write_ex(SSL *s, const void *buf, size_t num, size_t *written);
|
|
int SSL_write(SSL *ssl, const void *buf, int num);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
SSL_write_ex() and SSL_write() write B<num> bytes from the buffer B<buf> into
|
|
the specified B<ssl> connection. On success SSL_write_ex() will store the number
|
|
of bytes written in B<*written>.
|
|
|
|
SSL_sendfile() writes B<size> bytes from offset B<offset> in the file
|
|
descriptor B<fd> to the specified SSL connection B<s>. This function provides
|
|
efficient zero-copy semantics. SSL_sendfile() is available only when
|
|
Kernel TLS is enabled, which can be checked by calling BIO_get_ktls_send().
|
|
It is provided here to allow users to maintain the same interface.
|
|
The meaning of B<flags> is platform dependent.
|
|
Currently, under Linux it is ignored.
|
|
|
|
=head1 NOTES
|
|
|
|
In the paragraphs below a "write function" is defined as one of either
|
|
SSL_write_ex(), or SSL_write().
|
|
|
|
If necessary, a write function will negotiate a TLS/SSL session, if not already
|
|
explicitly performed by L<SSL_connect(3)> or L<SSL_accept(3)>. If the peer
|
|
requests a re-negotiation, it will be performed transparently during
|
|
the write function operation. The behaviour of the write functions depends on the
|
|
underlying BIO.
|
|
|
|
For the transparent negotiation to succeed, the B<ssl> must have been
|
|
initialized to client or server mode. This is being done by calling
|
|
L<SSL_set_connect_state(3)> or SSL_set_accept_state()
|
|
before the first call to a write function.
|
|
|
|
If the underlying BIO is B<blocking>, the write functions will only return, once
|
|
the write operation has been finished or an error occurred.
|
|
|
|
If the underlying BIO is B<non-blocking> the write functions will also return
|
|
when the underlying BIO could not satisfy the needs of the function to continue
|
|
the operation. In this case a call to L<SSL_get_error(3)> with the
|
|
return value of the write function will yield B<SSL_ERROR_WANT_READ>
|
|
or B<SSL_ERROR_WANT_WRITE>. As at any time a re-negotiation is possible, a
|
|
call to a write function can also cause read operations! The calling process
|
|
then must repeat the call after taking appropriate action to satisfy the needs
|
|
of the write function. The action depends on the underlying BIO. When using a
|
|
non-blocking socket, nothing is to be done, but select() can be used to check
|
|
for the required condition. When using a buffering BIO, like a BIO pair, data
|
|
must be written into or retrieved out of the BIO before being able to continue.
|
|
|
|
The write functions will only return with success when the complete contents of
|
|
B<buf> of length B<num> has been written. This default behaviour can be changed
|
|
with the SSL_MODE_ENABLE_PARTIAL_WRITE option of L<SSL_CTX_set_mode(3)>. When
|
|
this flag is set the write functions will also return with success when a
|
|
partial write has been successfully completed. In this case the write function
|
|
operation is considered completed. The bytes are sent and a new write call with
|
|
a new buffer (with the already sent bytes removed) must be started. A partial
|
|
write is performed with the size of a message block, which is 16kB.
|
|
|
|
=head1 WARNING
|
|
|
|
When a write function call has to be repeated because L<SSL_get_error(3)>
|
|
returned B<SSL_ERROR_WANT_READ> or B<SSL_ERROR_WANT_WRITE>, it must be repeated
|
|
with the same arguments.
|
|
The data that was passed might have been partially processed.
|
|
When B<SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER> was set using L<SSL_CTX_set_mode(3)>
|
|
the pointer can be different, but the data and length should still be the same.
|
|
|
|
You should not call SSL_write() with num=0, it will return an error.
|
|
SSL_write_ex() can be called with num=0, but will not send application data to
|
|
the peer.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
SSL_write_ex() will return 1 for success or 0 for failure. Success means that
|
|
all requested application data bytes have been written to the SSL connection or,
|
|
if SSL_MODE_ENABLE_PARTIAL_WRITE is in use, at least 1 application data byte has
|
|
been written to the SSL connection. Failure means that not all the requested
|
|
bytes have been written yet (if SSL_MODE_ENABLE_PARTIAL_WRITE is not in use) or
|
|
no bytes could be written to the SSL connection (if
|
|
SSL_MODE_ENABLE_PARTIAL_WRITE is in use). Failures can be retryable (e.g. the
|
|
network write buffer has temporarily filled up) or non-retryable (e.g. a fatal
|
|
network error). In the event of a failure call L<SSL_get_error(3)> to find out
|
|
the reason which indicates whether the call is retryable or not.
|
|
|
|
For SSL_write() the following return values can occur:
|
|
|
|
=over 4
|
|
|
|
=item E<gt> 0
|
|
|
|
The write operation was successful, the return value is the number of
|
|
bytes actually written to the TLS/SSL connection.
|
|
|
|
=item Z<><= 0
|
|
|
|
The write operation was not successful, because either the connection was
|
|
closed, an error occurred or action must be taken by the calling process.
|
|
Call SSL_get_error() with the return value B<ret> to find out the reason.
|
|
|
|
Old documentation indicated a difference between 0 and -1, and that -1 was
|
|
retryable.
|
|
You should instead call SSL_get_error() to find out if it's retryable.
|
|
|
|
=back
|
|
|
|
For SSL_sendfile(), the following return values can occur:
|
|
|
|
=over 4
|
|
|
|
=item Z<>>= 0
|
|
|
|
The write operation was successful, the return value is the number
|
|
of bytes of the file written to the TLS/SSL connection.
|
|
|
|
=item E<lt> 0
|
|
|
|
The write operation was not successful, because either the connection was
|
|
closed, an error occured or action must be taken by the calling process.
|
|
Call SSL_get_error() with the return value to find out the reason.
|
|
|
|
=back
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<SSL_get_error(3)>, L<SSL_read_ex(3)>, L<SSL_read(3)>
|
|
L<SSL_CTX_set_mode(3)>, L<SSL_CTX_new(3)>,
|
|
L<SSL_connect(3)>, L<SSL_accept(3)>
|
|
L<SSL_set_connect_state(3)>, L<BIO_ctrl(3)>,
|
|
L<ssl(7)>, L<bio(7)>
|
|
|
|
=head1 HISTORY
|
|
|
|
The SSL_write_ex() function was added in OpenSSL 1.1.1.
|
|
The SSL_sendfile() function was added in OpenSSL 3.0.0.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2019 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
|