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       1                 :            : /* suggest.c --- Suggest client mechanism to use, from a set of mechanisms.
       2                 :            :  * Copyright (C) 2002-2012 Simon Josefsson
       3                 :            :  *
       4                 :            :  * This file is part of GNU SASL Library.
       5                 :            :  *
       6                 :            :  * GNU SASL Library is free software; you can redistribute it and/or
       7                 :            :  * modify it under the terms of the GNU Lesser General Public License
       8                 :            :  * as published by the Free Software Foundation; either version 2.1 of
       9                 :            :  * the License, or (at your option) any later version.
      10                 :            :  *
      11                 :            :  * GNU SASL Library is distributed in the hope that it will be useful,
      12                 :            :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      13                 :            :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14                 :            :  * Lesser General Public License for more details.
      15                 :            :  *
      16                 :            :  * You should have received a copy of the GNU Lesser General Public
      17                 :            :  * License License along with GNU SASL Library; if not, write to the
      18                 :            :  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
      19                 :            :  * Boston, MA 02110-1301, USA.
      20                 :            :  *
      21                 :            :  */
      22                 :            : 
      23                 :            : #include "internal.h"
      24                 :            : 
      25                 :            : /**
      26                 :            :  * gsasl_client_suggest_mechanism:
      27                 :            :  * @ctx: libgsasl handle.
      28                 :            :  * @mechlist: input character array with SASL mechanism names,
      29                 :            :  *   separated by invalid characters (e.g. SPC).
      30                 :            :  *
      31                 :            :  * Given a list of mechanisms, suggest which to use.
      32                 :            :  *
      33                 :            :  * Return value: Returns name of "best" SASL mechanism supported by
      34                 :            :  *   the libgsasl client which is present in the input string, or
      35                 :            :  *   NULL if no supported mechanism is found.
      36                 :            :  **/
      37                 :            : const char *
      38                 :          6 : gsasl_client_suggest_mechanism (Gsasl * ctx, const char *mechlist)
      39                 :            : {
      40                 :            :   size_t mechlist_len, target_mech, i;
      41                 :            : 
      42         [ +  - ]:          6 :   mechlist_len = mechlist ? strlen (mechlist) : 0;
      43                 :          6 :   target_mech = ctx->n_client_mechs; /* ~ no target */
      44                 :            : 
      45         [ +  + ]:         33 :   for (i = 0; i < mechlist_len;)
      46                 :            :     {
      47                 :            :       size_t len;
      48                 :            : 
      49                 :         27 :       len = strspn (mechlist + i, GSASL_VALID_MECHANISM_CHARACTERS);
      50         [ -  + ]:         27 :       if (!len)
      51                 :          0 :         ++i;
      52                 :            :       else
      53                 :            :         {
      54                 :            :           size_t j;
      55                 :            : 
      56                 :            :           /* Assumption: the mechs array is sorted by preference
      57                 :            :            * from low security to high security. */
      58 [ +  + ][ +  + ]:        213 :           for (j = (target_mech < ctx->n_client_mechs ? target_mech + 1 : 0);
      59                 :        186 :                j < ctx->n_client_mechs; ++j)
      60                 :            :             {
      61         [ +  + ]:        193 :               if (strncmp (ctx->client_mechs[j].name, mechlist + i, len) == 0)
      62                 :            :                 {
      63                 :            :                   Gsasl_session *sctx;
      64                 :            : 
      65         [ +  - ]:          7 :                   if (gsasl_client_start (ctx, ctx->client_mechs[j].name,
      66                 :            :                                           &sctx) == GSASL_OK)
      67                 :            :                     {
      68                 :          7 :                       gsasl_finish (sctx);
      69                 :          7 :                       target_mech = j;
      70                 :            :                     }
      71                 :            : 
      72                 :          7 :                   break;
      73                 :            :                 }
      74                 :            :             }
      75                 :         27 :           i += len + 1;
      76                 :            :         }
      77                 :            :     }
      78                 :            : 
      79                 :          6 :   return target_mech < ctx->n_client_mechs ?
      80         [ +  + ]:          6 :     ctx->client_mechs[target_mech].name : NULL;
      81                 :            : }