LXR syslinux/gpxe/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
  19FILE_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 */
  46int 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 */
  80void 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 */
  99void 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 */
 117void 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}
 125