/* client-mech.c --- Example SASL client, with a choice of mechanism to use.
 * Copyright (C) 2004-2026 Simon Josefsson
 *
 * This file is part of GNU SASL.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <config.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <gsasl.h>

static void
client_authenticate (Gsasl_session *session)
{
  char buf[BUFSIZ] = "";
  char *p;
  int rc;

  /* This loop mimics a protocol where the server send data first. */

  do
    {
      printf ("Input base64 encoded data from server:\n");
      p = fgets (buf, sizeof (buf) - 1, stdin);
      if (p == NULL)
	{
	  perror ("fgets");
	  return;
	}
      if (buf[strlen (buf) - 1] == '\n')
	buf[strlen (buf) - 1] = '\0';

      rc = gsasl_step64 (session, buf, &p);

      if (rc == GSASL_NEEDS_MORE || rc == GSASL_OK)
	{
	  printf ("Output:\n%s\n", p);
	  gsasl_free (p);
	}
    }
  while (rc == GSASL_NEEDS_MORE);

  printf ("\n");

  if (rc != GSASL_OK)
    {
      printf ("Authentication error (%d): %s\n", rc, gsasl_strerror (rc));
      return;
    }

  /* The client is done.  Here you would typically check if the server
     let the client in.  If not, you could try again. */

  printf ("If server accepted us, we're done.\n");
}

static const char *
client_mechanism (Gsasl *ctx)
{
  static char mech[GSASL_MAX_MECHANISM_SIZE + 1] = "";
  char mechlist[BUFSIZ] = "";
  const char *suggestion;
  char *p;

  printf ("Enter list of server supported mechanisms, separate by SPC:\n");
  p = fgets (mechlist, sizeof (mechlist) - 1, stdin);
  if (p == NULL)
    {
      perror ("fgets");
      return NULL;
    }

  suggestion = gsasl_client_suggest_mechanism (ctx, mechlist);
  if (suggestion)
    printf ("Library suggests use of `%s'.\n", suggestion);

  printf ("Enter mechanism to use:\n");
  p = fgets (mech, sizeof (mech) - 1, stdin);
  if (p == NULL)
    {
      perror ("fgets");
      return NULL;
    }

  mech[strlen (mech) - 1] = '\0';

  return mech;
}

static void
client (Gsasl *ctx)
{
  Gsasl_session *session;
  const char *mech;
  int rc;

  /* Find out which mechanism to use. */
  mech = client_mechanism (ctx);

  /* Create new authentication session. */
  if ((rc = gsasl_client_start (ctx, mech, &session)) != GSASL_OK)
    {
      printf ("Cannot initialize client (%d): %s\n", rc, gsasl_strerror (rc));
      return;
    }

  /* Set username and password in session handle.  This info will be
     lost when this session is deallocated below.  */
  rc = gsasl_property_set (session, GSASL_AUTHID, "jas");
  if (rc != GSASL_OK)
    {
      printf ("Cannot set property (%d): %s\n", rc, gsasl_strerror (rc));
      return;
    }
  rc = gsasl_property_set (session, GSASL_PASSWORD, "secret");
  if (rc != GSASL_OK)
    {
      printf ("Cannot set property (%d): %s\n", rc, gsasl_strerror (rc));
      return;
    }

  /* Do it. */
  client_authenticate (session);

  /* Cleanup. */
  gsasl_finish (session);
}

int
main (void)
{
  Gsasl *ctx = NULL;
  int rc;

  /* Initialize library. */
  if ((rc = gsasl_init (&ctx)) != GSASL_OK)
    {
      printf ("Cannot initialize libgsasl (%d): %s", rc, gsasl_strerror (rc));
      return 1;
    }

  /* Do it. */
  client (ctx);

  /* Cleanup. */
  gsasl_done (ctx);

  return 0;
}
