sequence number checks, order and replay

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@12348 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/gssapi/sequence.c

@@ -0,0 +1,199 @@
+/*
+ * Copyright (c) 2003 Kungliga Tekniska H<>gskolan
+ * (Royal Institute of Technology, Stockholm, Sweden). 
+ * All rights reserved. 
+ *
+ * Redistribution and use in source and binary forms, with or without 
+ * modification, are permitted provided that the following conditions 
+ * are met: 
+ *
+ * 1. Redistributions of source code must retain the above copyright 
+ *    notice, this list of conditions and the following disclaimer. 
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright 
+ *    notice, this list of conditions and the following disclaimer in the 
+ *    documentation and/or other materials provided with the distribution. 
+ *
+ * 3. Neither the name of the Institute nor the names of its contributors 
+ *    may be used to endorse or promote products derived from this software 
+ *    without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
+ * SUCH DAMAGE. 
+ */
+
+#include "gssapi_locl.h"
+
+RCSID("$Id$");
+
+#define DEFAULT_JITTER_WINDOW 20
+
+struct gss_msg_order {
+    OM_uint32 flags;
+    OM_uint32 start;
+    OM_uint32 length;
+    OM_uint32 jitter_window;
+    OM_uint32 first_seq;
+    OM_uint32 elem[1];
+};
+
+/*
+ *
+ */
+
+OM_uint32
+gssapi_msg_order_create(OM_uint32 *minor_status,
+			struct gss_msg_order **o, 
+			OM_uint32 flags, 
+			OM_uint32 seq_num, 
+			OM_uint32 jitter_window)
+{
+    size_t len;
+
+    if (jitter_window == 0)
+	jitter_window = DEFAULT_JITTER_WINDOW;
+
+    len = jitter_window * sizeof((*o)->elem[0]);
+    len += sizeof(**o);
+    len -= sizeof((*o)->elem[0]);
+    
+    *o = malloc(len);
+    if (*o == NULL) {
+	*minor_status = ENOMEM;
+	return GSS_S_FAILURE;
+    }	
+    memset(*o, 0, len);
+    (*o)->flags = flags;
+    (*o)->length = 0;
+    (*o)->first_seq = seq_num;
+    (*o)->jitter_window = jitter_window;
+    (*o)->elem[0] = seq_num - 1;
+
+    *minor_status = 0;
+    return GSS_S_COMPLETE;
+}
+
+OM_uint32
+gssapi_msg_order_destroy(struct gss_msg_order **m)
+{
+    free(*m);
+    *m = NULL;
+    return GSS_S_COMPLETE;
+}
+
+static void
+elem_set(struct gss_msg_order *o, unsigned int slot, OM_uint32 val)
+{
+    o->elem[slot % o->jitter_window] = val;
+}
+
+#if 0
+static OM_uint32
+elem_get(struct gss_msg_order *o, unsigned int slot)
+{
+    return o->elem[slot % o->jitter_window];
+}
+#endif
+
+static void
+elem_insert(struct gss_msg_order *o, 
+	    unsigned int after_slot,
+	    OM_uint32 seq_num)
+{
+    assert(o->jitter_window > after_slot);
+
+    if (o->length > after_slot)
+	memmove(&o->elem[after_slot + 1], &o->elem[after_slot],
+		(o->length - after_slot) * sizeof(o->elem[0]));
+
+    elem_set(o, after_slot, seq_num);
+
+    if (o->length < o->jitter_window)
+	o->length++;
+}
+
+#if 0
+static int
+elem_samep(struct gss_msg_order *o,
+	   unsigned int slot,
+	   OM_uint32 value)
+{
+    return elem_get(o, slot) == value;
+}
+#endif
+
+/* rule 1: expected sequence number */
+/* rule 2: > expected sequence number */
+/* rule 3: seqnum < seqnum(first) */
+/* rule 4+5: seqnum in [seqnum(first),seqnum(last)]  */
+
+OM_uint32
+gssapi_msg_order_check(struct gss_msg_order *o, OM_uint32 seq_num)
+{
+    OM_uint32 r;
+    int i;
+
+    if (o == NULL)
+	return GSS_S_COMPLETE;
+
+    if ((o->flags & (GSS_C_REPLAY_FLAG|GSS_C_SEQUENCE_FLAG)) == 0)
+	return GSS_S_COMPLETE;
+
+    /* check if the packet is the next in order */
+    if (o->elem[0] == seq_num - 1) {
+	elem_insert(o, 0, seq_num);
+	return GSS_S_COMPLETE;
+    }
+
+    r = (o->flags & (GSS_C_REPLAY_FLAG|GSS_C_SEQUENCE_FLAG))==GSS_C_REPLAY_FLAG;
+
+    /* sequence number larger then largest sequence number 
+     * or smaller then the first sequence number */
+    if (seq_num > o->elem[0]
+	|| seq_num < o->first_seq
+	|| o->length == 0) 
+    {
+	elem_insert(o, 0, seq_num);
+	if (r) {
+	    return GSS_S_COMPLETE;
+	} else {
+	    return GSS_S_GAP_TOKEN;
+	}
+    }
+
+    assert(o->length > 0);
+
+    /* sequence number smaller the first sequence number */
+    if (seq_num < o->elem[o->length - 1]) {
+	if (r)
+	    return(GSS_S_OLD_TOKEN);
+	else
+	    return(GSS_S_UNSEQ_TOKEN);
+    }
+
+    if (seq_num == o->elem[o->length-1])
+	return GSS_S_DUPLICATE_TOKEN;
+
+    for (i = 0; i < o->length - 1; i++) {
+	if (o->elem[i] == seq_num)
+	    return GSS_S_DUPLICATE_TOKEN;
+	if (o->elem[i + 1] < seq_num && o->elem[i] < seq_num) {
+	    elem_insert(o, i, seq_num);
+	    if (r)
+		return GSS_S_COMPLETE;
+	    else
+		return GSS_S_UNSEQ_TOKEN;
+	}
+    }
+
+    return GSS_S_FAILURE;
+}