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 #include <stddef.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <errno.h>
  23 #include <assert.h>
  24 #include <gpxe/crypto.h>
  25 #include <gpxe/chap.h>
  26
  27 /** @file
  28  *
  29  * CHAP protocol
  30  *
  31  */
  32
  33 /**
  34  * Initialise CHAP challenge/response
  35  *
  36  * @v chap              CHAP challenge/response
  37  * @v digest            Digest algorithm to use
  38  * @ret rc              Return status code
  39  *
  40  * Initialises a CHAP challenge/response structure.  This routine
  41  * allocates memory, and so may fail.  The allocated memory must
  42  * eventually be freed by a call to chap_finish().
  43  */
  44 int chap_init ( struct chap_challenge *chap,
  45                 struct crypto_algorithm *digest ) {
  46         size_t state_len;
  47         void *state;
  48
  49         assert ( chap->digest == NULL );
  50         assert ( chap->digest_context == NULL );
  51         assert ( chap->response == NULL );
  52
  53         DBG ( "CHAP %p initialising with %s digest\n", chap, digest->name );
  54
  55         state_len = ( digest->ctxsize + digest->digestsize );
  56         state = malloc ( state_len );
  57         if ( ! state ) {
  58                 DBG ( "CHAP %p could not allocate %d bytes for state\n",
  59                       chap, state_len );
  60                 return -ENOMEM;
  61         }
  62
  63         chap->digest = digest;
  64         chap->digest_context = state;
  65         chap->response = ( state + digest->ctxsize );
  66         chap->response_len = digest->digestsize;
  67         digest_init ( chap->digest, chap->digest_context );
  68         return 0;
  69 }
  70
  71 /**
  72  * Add data to the CHAP challenge
  73  *
  74  * @v chap              CHAP challenge/response
  75  * @v data              Data to add
  76  * @v len               Length of data to add
  77  */
  78 void chap_update ( struct chap_challenge *chap, const void *data,
  79                    size_t len ) {
  80         assert ( chap->digest != NULL );
  81         assert ( chap->digest_context != NULL );
  82
  83         if ( ! chap->digest )
  84                 return;
  85
  86         digest_update ( chap->digest, chap->digest_context, data, len );
  87 }
  88
  89 /**
  90  * Respond to the CHAP challenge
  91  *
  92  * @v chap              CHAP challenge/response
  93  *
  94  * Calculates the final CHAP response value, and places it in @c
  95  * chap->response, with a length of @c chap->response_len.
  96  */
  97 void chap_respond ( struct chap_challenge *chap ) {
  98         assert ( chap->digest != NULL );
  99         assert ( chap->digest_context != NULL );
 100         assert ( chap->response != NULL );
 101
 102         DBG ( "CHAP %p responding to challenge\n", chap );
 103
 104         if ( ! chap->digest )
 105                 return;
 106
 107         digest_final ( chap->digest, chap->digest_context, chap->response );
 108 }
 109
 110 /**
 111  * Free resources used by a CHAP challenge/response
 112  *
 113  * @v chap              CHAP challenge/response
 114  */
 115 void chap_finish ( struct chap_challenge *chap ) {
 116         void *state = chap->digest_context;
 117
 118         DBG ( "CHAP %p finished\n", chap );
 119
 120         free ( state );
 121         memset ( chap, 0, sizeof ( *chap ) );
 122 }