/xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
0.9.7e/doc/ssl
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SSL_CTX_set_msg_callbac15/Aug/2002 (0.SSL_CTX_set_msg_callback(3)
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
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);
DESCRIPTION
SSL_CTX_set_msg_callback() or SSL_set_msg_callback() can be
used to define a message callback function 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
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 SSL objects by SSL_new(3).
SSL_set_msg_callback() and SSL_set_msg_callback_arg() modify
the actual settings of an SSL object. Using a 0 pointer for
cb disables the message callback.
When cb is called by the SSL/TLS library for a protocol
message, the function arguments have the following meaning:
write_p
This flag is 0 when a protocol message has been received
and 1 when a protocol message has been sent.
version
The protocol version according to which the protocol
message is interpreted by the library. Currently, this
is one of SSL2_VERSION, SSL3_VERSION and TLS1_VERSION
(for SSL 2.0, SSL 3.0 and TLS 1.0, respectively).
content_type
In the case of SSL 2.0, this is always 0. In the case
of SSL 3.0 or TLS 1.0, this is one of the ContentType
values defined in the protocol specification
(change_cipher_spec(20), alert(21), handshake(22); but
never application_data(23) because the callback will
only be called for protocol messages).
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SSL_CTX_set_msg_callbac15/Aug/2002 (0.SSL_CTX_set_msg_callback(3)
buf, len
buf points to a buffer containing the protocol message,
which consists of len bytes. The buffer is no longer
valid after the callback function has returned.
ssl The SSL object that received or sent the message.
arg The user-defined argument optionally defined by
SSL_CTX_set_msg_callback_arg() or
SSL_set_msg_callback_arg().
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, 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, version will be SSL3_VERSION.
SEE ALSO
ssl(3), SSL_new(3)
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.
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