src/crypto/chap.c

   1 /*
   2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <stddef.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <errno.h>
  25 #include <assert.h>
  26 #include <gpxe/crypto.h>
  27 #include <gpxe/chap.h>
  28
  29 /** @file
  30  *
  31  * CHAP protocol
  32  *
  33  */
  34
  35 /**
  36  * Initialise CHAP challenge/response
  37  *
  38  * @v chap              CHAP challenge/response
  39  * @v digest            Digest algorithm to use
  40  * @ret rc              Return status code
  41  *
  42  * Initialises a CHAP challenge/response structure.  This routine
  43  * allocates memory, and so may fail.  The allocated memory must
  44  * eventually be freed by a call to chap_finish().
  45  */
  46 int chap_init ( struct chap_response *chap,
  47                 struct digest_algorithm *digest ) {
  48         size_t state_len;
  49         void *state;
  50
  51         assert ( chap->digest == NULL );
  52         assert ( chap->digest_context == NULL );
  53         assert ( chap->response == NULL );
  54
  55         DBG ( "CHAP %p initialising with %s digest\n", chap, digest->name );
  56
  57         state_len = ( digest->ctxsize + digest->digestsize );
  58         state = malloc ( state_len );
  59         if ( ! state ) {
  60                 DBG ( "CHAP %p could not allocate %zd bytes for state\n",
  61                       chap, state_len );
  62                 return -ENOMEM;
  63         }
  64
  65         chap->digest = digest;
  66         chap->digest_context = state;
  67         chap->response = ( state + digest->ctxsize );
  68         chap->response_len = digest->digestsize;
  69         digest_init ( chap->digest, chap->digest_context );
  70         return 0;
  71 }
  72
  73 /**
  74  * Add data to the CHAP challenge
  75  *
  76  * @v chap              CHAP response
  77  * @v data              Data to add
  78  * @v len               Length of data to add
  79  */
  80 void chap_update ( struct chap_response *chap, const void *data,
  81                    size_t len ) {
  82         assert ( chap->digest != NULL );
  83         assert ( chap->digest_context != NULL );
  84
  85         if ( ! chap->digest )
  86                 return;
  87
  88         digest_update ( chap->digest, chap->digest_context, data, len );
  89 }
  90
  91 /**
  92  * Respond to the CHAP challenge
  93  *
  94  * @v chap              CHAP response
  95  *
  96  * Calculates the final CHAP response value, and places it in @c
  97  * chap->response, with a length of @c chap->response_len.
  98  */
  99 void chap_respond ( struct chap_response *chap ) {
 100         assert ( chap->digest != NULL );
 101         assert ( chap->digest_context != NULL );
 102         assert ( chap->response != NULL );
 103
 104         DBG ( "CHAP %p responding to challenge\n", chap );
 105
 106         if ( ! chap->digest )
 107                 return;
 108
 109         digest_final ( chap->digest, chap->digest_context, chap->response );
 110 }
 111
 112 /**
 113  * Free resources used by a CHAP response
 114  *
 115  * @v chap              CHAP response
 116  */
 117 void chap_finish ( struct chap_response *chap ) {
 118         void *state = chap->digest_context;
 119
 120         DBG ( "CHAP %p finished\n", chap );
 121
 122         free ( state );
 123         memset ( chap, 0, sizeof ( *chap ) );
 124 }