100 lines
3.4 KiB
Plaintext
100 lines
3.4 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
SSL_CTX_set_msg_callback, SSL_CTX_set_msg_callback_arg, SSL_set_msg_callback, SSL_get_msg_callback_arg - install callback for observing protocol messages
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/ssl.h>
|
|
|
|
void SSL_CTX_set_msg_callback(SSL_CTX *ctx, void (*cb)(int write_p, int version, int content_type, const void *buf, size_t len, SSL *ssl, void *arg));
|
|
void SSL_CTX_set_msg_callback_arg(SSL_CTX *ctx, void *arg);
|
|
|
|
void SSL_set_msg_callback(SSL_CTX *ctx, void (*cb)(int write_p, int version, int content_type, const void *buf, size_t len, SSL *ssl, void *arg));
|
|
void SSL_set_msg_callback_arg(SSL_CTX *ctx, void *arg);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
SSL_CTX_set_msg_callback() or SSL_set_msg_callback() can be used to
|
|
define a message callback function I<cb> for observing all SSL/TLS
|
|
protocol messages (such as handshake messages) that are received or
|
|
sent. SSL_CTX_set_msg_callback_arg() and SSL_set_msg_callback_arg()
|
|
can be used to set argument I<arg> to the callback function, which is
|
|
available for arbitrary application use.
|
|
|
|
SSL_CTX_set_msg_callback() and SSL_CTX_set_msg_callback_arg() specify
|
|
default settings that will be copied to new B<SSL> objects by
|
|
L<SSL_new(3)|SSL_new(3)>. SSL_set_msg_callback() and
|
|
SSL_set_msg_callback_arg() modify the actual settings of an B<SSL>
|
|
object. Using a B<0> pointer for I<cb> disables the message callback.
|
|
|
|
When I<cb> is called by the SSL/TLS library for a protocol message,
|
|
the function arguments have the following meaning:
|
|
|
|
=over 4
|
|
|
|
=item I<write_p>
|
|
|
|
This flag is B<0> when a protocol message has been received and B<1>
|
|
when a protocol message has been sent.
|
|
|
|
=item I<version>
|
|
|
|
The protocol version according to which the protocol message is
|
|
interpreted by the library. Currently, this is one of
|
|
B<SSL2_VERSION>, B<SSL3_VERSION> and B<TLS1_VERSION> (for SSL 2.0, SSL
|
|
3.0 and TLS 1.0, respectively).
|
|
|
|
=item I<content_type>
|
|
|
|
In the case of SSL 2.0, this is always B<0>. In the case of SSL 3.0
|
|
or TLS 1.0, this is one of the B<ContentType> values defined in the
|
|
protocol specification (B<change_cipher_spec(20)>, B<alert(21)>,
|
|
B<handshake(22)>; but never B<application_data(23)> because the
|
|
callback will only be called for protocol messages).
|
|
|
|
=item I<buf>, I<len>
|
|
|
|
I<buf> points to a buffer containing the protocol message, which
|
|
consists of I<len> bytes. The buffer is no longer valid after the
|
|
callback function has returned.
|
|
|
|
=item I<ssl>
|
|
|
|
The B<SSL> object that received or sent the message.
|
|
|
|
=item I<arg>
|
|
|
|
The user-defined argument optionally defined by
|
|
SSL_CTX_set_msg_callback_arg() or SSL_set_msg_callback_arg().
|
|
|
|
=back
|
|
|
|
=head1 NOTES
|
|
|
|
Protocol messages are passed to the callback function after decryption
|
|
and fragment collection where applicable. (Thus record boundaries are
|
|
not visible.)
|
|
|
|
If processing a received protocol message results in an error,
|
|
the callback function may not be called. For example, the callback
|
|
function will never see messages that are considered too large to be
|
|
processed.
|
|
|
|
Due to automatic protocol version negotiation, I<version> is not
|
|
necessarily the protocol version used by the sender of the message: If
|
|
a TLS 1.0 ClientHello message is received by an SSL 3.0-only server,
|
|
I<version> will be B<SSL3_VERSION>.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ssl(3)|ssl(3)>, L<SSL_new(3)|SSL_new(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
SSL_CTX_set_msg_callback(), SSL_CTX_set_msg_callback_arg(),
|
|
SSL_set_msg_callback() and SSL_get_msg_callback_arg() were added in OpenSSL 0.9.7.
|
|
|
|
=cut
|