SSLCTXsetmsgcallback(3) OpenSSL SSLCTXsetmsgcallback(3)

NAME
       SSLCTXsetmsgcallback, SSLCTXsetmsgcallbackarg,
       SSLsetmsgcallback, SSLgetmsgcallbackarg - install callback for
       observing protocol messages

SYNOPSIS
        #include 

        void SSLCTXsetmsgcallback(SSLCTX *ctx, void (*cb)(int writep, int version, int contenttype, const void *buf, sizet len, SSL *ssl, void *arg));
        void SSLCTXsetmsgcallbackarg(SSLCTX *ctx, void *arg);

        void SSLsetmsgcallback(SSLCTX *ctx, void (*cb)(int writep, int version, int contenttype, const void *buf, sizet len, SSL *ssl, void *arg));
        void SSLsetmsgcallbackarg(SSLCTX *ctx, void *arg);

DESCRIPTION
       SSLCTXsetmsgcallback() or SSLsetmsgcallback() 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.  SSLCTXsetmsgcallbackarg() and SSLsetmsgcallbackarg()
       can be used to set argument arg to the callback function, which is
       available for arbitrary application use.

       SSLCTXsetmsgcallback() and SSLCTXsetmsgcallbackarg() specify
       default settings that will be copied to new SSSSLL objects by SSLnew(3).
       SSLsetmsgcallback() and SSLsetmsgcallbackarg() modify the actual
       settings of an SSSSLL object. Using a 00 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:

       writep
           This flag is 00 when a protocol message has been received and 11 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 SSSSLL22VVEERRSSIIOONN,
           SSSSLL33VVEERRSSIIOONN and TTLLSS11VVEERRSSIIOONN (for SSL 2.0, SSL 3.0 and TLS 1.0,
           respectively).

       contenttype
           In the case of SSL 2.0, this is always 00.  In the case of SSL 3.0
           or TLS 1.0, this is one of the CCoonntteennttTTyyppee values defined in the
           protocol specification (cchhaannggeecciipphheerrssppeecc((2200)), aalleerrtt((2211)),
           hhaannddsshhaakkee((2222)); but never aapppplliiccaattiioonnddaattaa((2233)) because the callback
           will only be called for protocol messages).

       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 SSSSLL object that received or sent the message.

       arg The user-defined argument optionally defined by
           SSLCTXsetmsgcallbackarg() or SSLsetmsgcallbackarg().

NNOOTTEESS
       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 SSSSLL33VVEERRSSIIOONN.

SEE ALSO
       ssl(3), SSLnew(3)

HISTORY       SSLCTXsetmsgcallback(), SSLCTXsetmsgcallbackarg(),
       SSLsetmsgcallback() and SSLgetmsgcallbackarg() were added in
       OpenSSL 0.9.7.



0.9.7l                            2002-08-15       SSLCTXsetmsgcallback(3)