# sasl_client_step - Perform a step in the authentication negotiation

## Synopsis

    #include <sasl/sasl.h>

    int sasl_client_step(sasl_conn_t *conn,
                   const char *serverin,
                   unsigned serverinlen,
                   sasl_interact_t ** prompt_need,
                   const char ** clientout,
                   unsigned * clientoutlen);

## Description

int sasl_client_step(sasl_conn_t *conn,
const char *serverin,
unsigned serverinlen,
sasl_interact_t ** prompt_need,
const char ** clientout,
unsigned * clientoutlen);

  sasl_client_step() performs a step in the authentication negotiation. It returns `SASL_OK` if the whole negotiation is successful and `SASL_CONTINUE` if this step is ok but at least one more step is needed. A client should not assume an authentication negotiation is successful just because the server signaled success via protocol (i.e. if the server said “. OK Authentication succeeded” in IMAP, sasl_client_step should still be called one more time with a serverinlen of zero.

  If `SASL_INTERACT` is returned the library needs some values to be filled in before it can proceed. The prompt_need structure will be filled in with requests. The application should fulfill these requests and call sasl_client_start again with identical parameters (the prompt_need parameter will be the same pointer as before but filled in by the application).

  Parameters:

    - conn – is the SASL connection context

    - serverin – is the data given by the server (decoded if the protocol encodes requests sent over the wire)

    - serverinlen – is the length of serverin

    - clientout – is created. It is the initial client response to send to the server. It is the job of the client to send it over the network to the server. Any protocol specific encoding (such as base64 encoding) nec‐ essary needs to be done by the client.

    - clientoutlen – length of clientout.

## Return Value

SASL callback functions should return SASL return codes. See sasl.h for a complete list. `SASL_CONTINUE` indicates success and that there are more steps needed in the authentication. `SASL_OK` indicates that the authentication is complete.

Other return codes indicate errors and should either be handled or the authentication session should be quit.

## See Also

RFC 4422,:saslman:sasl(3), sasl_callbacks(3), sasl_client_init(3), sasl_client_new(3), sasl_client_start(3), sasl_errors(3)