Defining a negotiation callback

A negotiation callback is defined as follows:

CS_RETCODE CS_PUBLIC
 negotiation_cb(connection, inmsgid,
                 outmsgid, inbuffmt, inbuf, outbuffmt,
                 outbuf, outbufoutlen)
 
 CS_CONNECTION   *connection;
 CS_INT                      inmsgid;
 CS_INT                      *outmsgid;
 CS_DATAFMT            *inbuffmt;
 CS_BYTE                   *inbuf;
 CS_DATAFMT            *outbuffmt;
 CS_BYTE                   *outbuf;
 CS_INT                      *outbufoutlen;

where:

A negotiation callback must return CS_SUCCEED, CS_FAIL, or CS_CONTINUE: