lib/gssapi/sequence.c

   1 /*
   2  * Copyright (c) 2003 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "gssapi_locl.h"
  35
  36 RCSID("$Id$");
  37
  38 #define DEFAULT_JITTER_WINDOW 20
  39
  40 struct gss_msg_order {
  41     OM_uint32 flags;
  42     OM_uint32 start;
  43     OM_uint32 length;
  44     OM_uint32 jitter_window;
  45     OM_uint32 first_seq;
  46     OM_uint32 elem[1];
  47 };
  48
  49 /*
  50  *
  51  */
  52
  53 OM_uint32
  54 _gssapi_msg_order_create(OM_uint32 *minor_status,
  55                          struct gss_msg_order **o,
  56                          OM_uint32 flags,
  57                          OM_uint32 seq_num,
  58                          OM_uint32 jitter_window,
  59                          int use_64)
  60 {
  61     size_t len;
  62
  63     if (jitter_window == 0)
  64         jitter_window = DEFAULT_JITTER_WINDOW;
  65
  66     len = jitter_window * sizeof((*o)->elem[0]);
  67     len += sizeof(**o);
  68     len -= sizeof((*o)->elem[0]);
  69
  70     *o = malloc(len);
  71     if (*o == NULL) {
  72         *minor_status = ENOMEM;
  73         return GSS_S_FAILURE;
  74     }
  75     memset(*o, 0, len);
  76     (*o)->flags = flags;
  77     (*o)->length = 0;
  78     (*o)->first_seq = seq_num;
  79     (*o)->jitter_window = jitter_window;
  80     (*o)->elem[0] = seq_num - 1;
  81
  82     *minor_status = 0;
  83     return GSS_S_COMPLETE;
  84 }
  85
  86 OM_uint32
  87 _gssapi_msg_order_destroy(struct gss_msg_order **m)
  88 {
  89     free(*m);
  90     *m = NULL;
  91     return GSS_S_COMPLETE;
  92 }
  93
  94 static void
  95 elem_set(struct gss_msg_order *o, unsigned int slot, OM_uint32 val)
  96 {
  97     o->elem[slot % o->jitter_window] = val;
  98 }
  99
 100 static void
 101 elem_insert(struct gss_msg_order *o,
 102             unsigned int after_slot,
 103             OM_uint32 seq_num)
 104 {
 105     assert(o->jitter_window > after_slot);
 106
 107     if (o->length > after_slot)
 108         memmove(&o->elem[after_slot + 1], &o->elem[after_slot],
 109                 (o->length - after_slot - 1) * sizeof(o->elem[0]));
 110
 111     elem_set(o, after_slot, seq_num);
 112
 113     if (o->length < o->jitter_window)
 114         o->length++;
 115 }
 116
 117 /* rule 1: expected sequence number */
 118 /* rule 2: > expected sequence number */
 119 /* rule 3: seqnum < seqnum(first) */
 120 /* rule 4+5: seqnum in [seqnum(first),seqnum(last)]  */
 121
 122 OM_uint32
 123 _gssapi_msg_order_check(struct gss_msg_order *o, OM_uint32 seq_num)
 124 {
 125     OM_uint32 r;
 126     int i;
 127
 128     if (o == NULL)
 129         return GSS_S_COMPLETE;
 130
 131     if ((o->flags & (GSS_C_REPLAY_FLAG|GSS_C_SEQUENCE_FLAG)) == 0)
 132         return GSS_S_COMPLETE;
 133
 134     /* check if the packet is the next in order */
 135     if (o->elem[0] == seq_num - 1) {
 136         elem_insert(o, 0, seq_num);
 137         return GSS_S_COMPLETE;
 138     }
 139
 140     r = (o->flags & (GSS_C_REPLAY_FLAG|GSS_C_SEQUENCE_FLAG))==GSS_C_REPLAY_FLAG;
 141
 142     /* sequence number larger then largest sequence number
 143      * or smaller then the first sequence number */
 144     if (seq_num > o->elem[0]
 145         || seq_num < o->first_seq
 146         || o->length == 0)
 147     {
 148         elem_insert(o, 0, seq_num);
 149         if (r) {
 150             return GSS_S_COMPLETE;
 151         } else {
 152             return GSS_S_GAP_TOKEN;
 153         }
 154     }
 155
 156     assert(o->length > 0);
 157
 158     /* sequence number smaller the first sequence number */
 159     if (seq_num < o->elem[o->length - 1]) {
 160         if (r)
 161             return(GSS_S_OLD_TOKEN);
 162         else
 163             return(GSS_S_UNSEQ_TOKEN);
 164     }
 165
 166     if (seq_num == o->elem[o->length - 1]) {
 167         return GSS_S_DUPLICATE_TOKEN;
 168     }
 169
 170     for (i = 0; i < o->length - 1; i++) {
 171         if (o->elem[i] == seq_num)
 172             return GSS_S_DUPLICATE_TOKEN;
 173         if (o->elem[i + 1] < seq_num && o->elem[i] < seq_num) {
 174             elem_insert(o, i, seq_num);
 175             if (r)
 176                 return GSS_S_COMPLETE;
 177             else
 178                 return GSS_S_UNSEQ_TOKEN;
 179         }
 180     }
 181
 182     return GSS_S_FAILURE;
 183 }
 184
 185 OM_uint32
 186 _gssapi_msg_order_f(OM_uint32 flags)
 187 {
 188     return flags & (GSS_C_SEQUENCE_FLAG|GSS_C_REPLAY_FLAG);
 189 }