=head1 NAME
-SSL_write_ex, SSL_write - write bytes to a TLS/SSL connection
+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);
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
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 functio operation. The behaviour of the write functions depends on the
+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
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, except when a
-renegotiation take place, in which case a SSL_ERROR_WANT_READ may occur.
-This behaviour can be controlled with the SSL_MODE_AUTO_RETRY flag of the
-L<SSL_CTX_set_mode(3)> call.
+the write operation has been finished or an error occurred.
-If the underlying BIO is B<non-blocking> the write functions will also return
+If the underlying BIO is B<nonblocking> 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>
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
+nonblocking 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.
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
+=head1 WARNINGS
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.
-When calling the write functions with num=0 bytes to be sent the behaviour is
-undefined.
+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_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 and if the call is retryable or not.
+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
+=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
+=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.
-The write operation was not successful. Probably the underlying connection
-was closed. Call SSL_get_error() with the return value B<ret> to find out,
-whether an error occurred or the connection was shut down cleanly
-(SSL_ERROR_ZERO_RETURN).
+=back
+
+For SSL_sendfile(), the following return values can occur:
-=item E<lt>0
+=over 4
-The write operation was not successful, because either 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.
+=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 occurred or action must be taken by the calling process.
+Call SSL_get_error() with the return value to find out the reason.
=back
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<ssl(3)>, L<bio(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.
=head1 COPYRIGHT
-Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
-Licensed under the OpenSSL license (the "License"). You may not use
+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>.
projects / openssl.git / blobdiff