SSL_CTX_set_msg_callback(3) OpenSSL 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 hand-
       shake messages) that are received or sent.
       SSL_CTX_set_msg_callback_arg() and SSL_set_msg_call-
       back_arg() can be used to set argument arg to the call-
       back function, which is available for arbitrary applica-
       tion use.

       SSL_CTX_set_msg_callback() and SSL_CTX_set_msg_call-
       back_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 set-
       tings of an SSL object. Using a 0 pointer for cb dis-
       ables the message callback.

       When cb is called by the SSL/TLS library for a protocol
       message, the function arguments have the following mean-
       ing:

       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 Con-
           tentType values defined in the protocol specifica-
           tion (change_cipher_spec(20), alert(21), hand-
           shake(22); but never application_data(23) because
           the callback will only be called for protocol mes-
           sages).

       buf, len
           buf points to a buffer containing the protocol mes-
           sage, 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_call-
           back_arg().

NOTES
       Protocol messages are passed to the callback function
       after decryption and fragment collection where applica-
       ble. (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_call-
       back_arg(), SSL_set_msg_callback() and SSL_get_msg_call-
       back_arg() were added in OpenSSL 0.9.7.



0.9.7c                     2002-08-1SSL_CTX_set_msg_callback(3)
