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551 lines
11 KiB
C
551 lines
11 KiB
C
/*
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* Copyright (C) 2008 Sun Microsystems, Inc.
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*
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* This file is part of Quagga.
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*
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* Quagga is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2, or (at your option) any
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* later version.
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*
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* Quagga is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Quagga; see the file COPYING. If not, write to the Free
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* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#include <zebra.h>
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#include <stdlib.h>
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#include <time.h>
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#include "checksum.h"
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struct thread_master *master;
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struct acc_vals {
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int c0;
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int c1;
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};
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struct csum_vals {
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struct acc_vals a;
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int x;
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int y;
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};
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static struct csum_vals ospfd_vals, isisd_vals;
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typedef size_t testsz_t;
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typedef uint16_t testoff_t;
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/* Fletcher Checksum -- Refer to RFC1008. */
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#define MODX 4102U
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/* The final reduction phase.
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* This one should be the original ospfd version
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*/
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static u_int16_t
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reduce_ospfd (struct csum_vals *vals, testsz_t len, testoff_t off)
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{
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#define x vals->x
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#define y vals->y
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#define c0 vals->a.c0
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#define c1 vals->a.c1
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x = ((len - off - 1) * c0 - c1) % 255;
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if (x <= 0)
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x += 255;
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y = 510 - c0 - x;
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if (y > 255)
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y -= 255;
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/* take care endian issue. */
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return htons ((x << 8) + y);
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#undef x
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#undef y
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#undef c0
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#undef c1
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}
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/* slightly different concatenation */
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static u_int16_t
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reduce_ospfd1 (struct csum_vals *vals, testsz_t len, testoff_t off)
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{
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#define x vals->x
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#define y vals->y
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#define c0 vals->a.c0
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#define c1 vals->a.c1
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x = ((len - off - 1) * c0 - c1) % 255;
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if (x <= 0)
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x += 255;
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y = 510 - c0 - x;
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if (y > 255)
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y -= 255;
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/* take care endian issue. */
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return htons ((x << 8) | (y & 0xff));
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#undef x
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#undef y
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#undef c0
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#undef c1
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}
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/* original isisd version */
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static u_int16_t
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reduce_isisd (struct csum_vals *vals, testsz_t len, testoff_t off)
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{
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#define x vals->x
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#define y vals->y
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#define c0 vals->a.c0
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#define c1 vals->a.c1
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u_int32_t mul;
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mul = (len - off)*(c0);
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x = mul - c0 - c1;
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y = c1 - mul - 1;
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if (y > 0)
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y++;
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if (x < 0)
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x--;
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x %= 255;
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y %= 255;
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if (x == 0)
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x = 255;
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if (y == 0)
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y = 1;
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return htons ((x << 8) | (y & 0xff));
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#undef x
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#undef y
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#undef c0
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#undef c1
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}
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/* Is the -1 in y wrong perhaps? */
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static u_int16_t
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reduce_isisd_yfix (struct csum_vals *vals, testsz_t len, testoff_t off)
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{
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#define x vals->x
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#define y vals->y
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#define c0 vals->a.c0
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#define c1 vals->a.c1
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u_int32_t mul;
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mul = (len - off)*(c0);
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x = mul - c0 - c1;
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y = c1 - mul;
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if (y > 0)
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y++;
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if (x < 0)
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x--;
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x %= 255;
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y %= 255;
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if (x == 0)
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x = 255;
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if (y == 0)
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y = 1;
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return htons ((x << 8) | (y & 0xff));
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#undef x
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#undef y
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#undef c0
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#undef c1
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}
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/* Move the mods yp */
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static u_int16_t
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reduce_isisd_mod (struct csum_vals *vals, testsz_t len, testoff_t off)
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{
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#define x vals->x
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#define y vals->y
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#define c0 vals->a.c0
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#define c1 vals->a.c1
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u_int32_t mul;
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mul = (len - off)*(c0);
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x = mul - c1 - c0;
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y = c1 - mul - 1;
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x %= 255;
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y %= 255;
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if (y > 0)
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y++;
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if (x < 0)
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x--;
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if (x == 0)
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x = 255;
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if (y == 0)
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y = 1;
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return htons ((x << 8) | (y & 0xff));
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#undef x
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#undef y
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#undef c0
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#undef c1
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}
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/* Move the mods up + fix y */
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static u_int16_t
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reduce_isisd_mody (struct csum_vals *vals, testsz_t len, testoff_t off)
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{
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#define x vals->x
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#define y vals->y
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#define c0 vals->a.c0
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#define c1 vals->a.c1
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u_int32_t mul;
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mul = (len - off)*(c0);
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x = mul - c0 - c1;
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y = c1 - mul;
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x %= 255;
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y %= 255;
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if (y > 0)
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y++;
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if (x < 0)
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x--;
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if (x == 0)
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x = 255;
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if (y == 0)
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y = 1;
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return htons ((x << 8) | (y & 0xff));
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#undef x
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#undef y
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#undef c0
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#undef c1
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}
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struct reductions_t {
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const char *name;
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u_int16_t (*f) (struct csum_vals *, testsz_t, testoff_t);
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} reducts[] = {
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{ .name = "ospfd", .f = reduce_ospfd },
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{ .name = "ospfd-1", .f = reduce_ospfd1 },
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{ .name = "isisd", .f = reduce_isisd },
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{ .name = "isisd-yfix", .f = reduce_isisd_yfix },
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{ .name = "isisd-mod", .f = reduce_isisd_mod },
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{ .name = "isisd-mody", .f = reduce_isisd_mody },
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{ NULL, NULL },
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};
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/* The original ospfd checksum */
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static u_int16_t
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ospfd_checksum (u_char *buffer, testsz_t len, testoff_t off)
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{
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u_char *sp, *ep, *p, *q;
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int c0 = 0, c1 = 0;
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int x, y;
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u_int16_t checksum, *csum;
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csum = (u_int16_t *) (buffer + off);
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*(csum) = 0;
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sp = buffer;
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for (ep = sp + len; sp < ep; sp = q)
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{
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q = sp + MODX;
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if (q > ep)
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q = ep;
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for (p = sp; p < q; p++)
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{
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c0 += *p;
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c1 += c0;
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}
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c0 %= 255;
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c1 %= 255;
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}
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ospfd_vals.a.c0 = c0;
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ospfd_vals.a.c1 = c1;
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//printf ("%s: len %u, off %u, c0 %d, c1 %d\n",
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// __func__, len, off, c0, c1);
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x = ((int)(len - off - 1) * (int)c0 - (int)c1) % 255;
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if (x <= 0)
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x += 255;
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y = 510 - c0 - x;
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if (y > 255)
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y -= 255;
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ospfd_vals.x = x;
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ospfd_vals.y = y;
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buffer[off] = x;
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buffer[off + 1] = y;
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/* take care endian issue. */
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checksum = htons ((x << 8) | (y & 0xff));
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return (checksum);
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}
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/* the original, broken isisd checksum */
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static u_int16_t
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iso_csum_create (u_char * buffer, testsz_t len, testoff_t off)
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{
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u_int8_t *p;
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int x;
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int y;
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u_int32_t mul;
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u_int32_t c0;
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u_int32_t c1;
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u_int16_t checksum, *csum;
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int i, init_len, partial_len;
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checksum = 0;
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csum = (u_int16_t *) (buffer + off);
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*(csum) = checksum;
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p = buffer;
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c0 = 0;
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c1 = 0;
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init_len = len;
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while (len != 0)
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{
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partial_len = MIN(len, MODX);
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for (i = 0; i < partial_len; i++)
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{
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c0 = c0 + *(p++);
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c1 += c0;
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}
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c0 = c0 % 255;
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c1 = c1 % 255;
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len -= partial_len;
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}
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isisd_vals.a.c0 = c0;
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isisd_vals.a.c1 = c1;
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mul = (init_len - off) * c0;
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x = mul - c1 - c0;
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y = c1 - mul - 1;
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if (y > 0)
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y++;
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if (x < 0)
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x--;
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x %= 255;
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y %= 255;
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if (x == 0)
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x = 255;
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if (y == 0)
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y = 1;
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isisd_vals.x = x;
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isisd_vals.y = y;
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checksum = htons((x << 8) | (y & 0xFF));
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*(csum) = checksum;
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/* return the checksum for user usage */
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return checksum;
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}
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static int
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verify (u_char * buffer, testsz_t len)
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{
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u_int8_t *p;
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u_int32_t c0;
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u_int32_t c1;
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int i, partial_len;
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p = buffer;
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c0 = 0;
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c1 = 0;
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while (len)
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{
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partial_len = MIN(len, 5803U);
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for (i = 0; i < partial_len; i++)
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{
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c0 = c0 + *(p++);
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c1 += c0;
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}
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c0 = c0 % 255;
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c1 = c1 % 255;
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len -= partial_len;
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}
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if (c0 == 0 && c1 == 0)
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return 0;
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return 1;
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}
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static int /* return checksum in low-order 16 bits */
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in_cksum_optimized(void *parg, int nbytes)
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{
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u_short *ptr = parg;
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register long sum; /* assumes long == 32 bits */
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register u_short answer; /* assumes u_short == 16 bits */
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register int count;
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/*
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* Our algorithm is simple, using a 32-bit accumulator (sum),
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* we add sequential 16-bit words to it, and at the end, fold back
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* all the carry bits from the top 16 bits into the lower 16 bits.
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*/
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sum = 0;
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count = nbytes >> 1; /* div by 2 */
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for(ptr--; count; --count)
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sum += *++ptr;
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if (nbytes & 1) /* Odd */
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sum += *(u_char *)(++ptr); /* one byte only */
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/*
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* Add back carry outs from top 16 bits to low 16 bits.
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*/
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sum = (sum >> 16) + (sum & 0xffff); /* add high-16 to low-16 */
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sum += (sum >> 16); /* add carry */
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answer = ~sum; /* ones-complement, then truncate to 16 bits */
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return(answer);
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}
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static int /* return checksum in low-order 16 bits */
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in_cksum_rfc(void *parg, int count)
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/* from RFC 1071 */
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{
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u_short *addr = parg;
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/* Compute Internet Checksum for "count" bytes
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* beginning at location "addr".
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*/
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register long sum = 0;
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while (count > 1) {
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/* This is the inner loop */
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sum += *addr++;
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count -= 2;
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}
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/* Add left-over byte, if any */
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if (count > 0) {
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sum += *(u_char *)addr;
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}
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/* Fold 32-bit sum to 16 bits */
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while (sum>>16)
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sum = (sum & 0xffff) + (sum >> 16);
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return ~sum;
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}
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int
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main(int argc, char **argv)
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{
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/* 60017 65629 702179 */
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#define MAXDATALEN 60017
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#define BUFSIZE MAXDATALEN + sizeof(u_int16_t)
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u_char buffer[BUFSIZE];
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int exercise = 0;
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#define EXERCISESTEP 257
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srandom (time (NULL));
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while (1) {
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u_int16_t ospfd, isisd, lib, in_csum, in_csum_res, in_csum_rfc;
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int i,j;
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exercise += EXERCISESTEP;
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exercise %= MAXDATALEN;
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for (i = 0; i < exercise; i += sizeof (long int)) {
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long int rand = random ();
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for (j = sizeof (long int); j > 0; j--)
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buffer[i + (sizeof (long int) - j)] = (rand >> (j * 8)) & 0xff;
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}
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in_csum = in_cksum(buffer, exercise);
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in_csum_res = in_cksum_optimized(buffer, exercise);
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in_csum_rfc = in_cksum_rfc(buffer, exercise);
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if (in_csum_res != in_csum || in_csum != in_csum_rfc)
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printf ("verify: in_chksum failed in_csum:%x, in_csum_res:%x,"
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"in_csum_rfc %x, len:%d\n",
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in_csum, in_csum_res, in_csum_rfc, exercise);
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ospfd = ospfd_checksum (buffer, exercise + sizeof(u_int16_t), exercise);
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if (verify (buffer, exercise + sizeof(u_int16_t)))
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printf ("verify: ospfd failed\n");
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isisd = iso_csum_create (buffer, exercise + sizeof(u_int16_t), exercise);
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if (verify (buffer, exercise + sizeof(u_int16_t)))
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printf ("verify: isisd failed\n");
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lib = fletcher_checksum (buffer, exercise + sizeof(u_int16_t), exercise);
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if (verify (buffer, exercise + sizeof(u_int16_t)))
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printf ("verify: lib failed\n");
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if (ospfd != lib) {
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printf ("Mismatch in values at size %u\n"
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"ospfd: 0x%04x\tc0: %d\tc1: %d\tx: %d\ty: %d\n"
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"isisd: 0x%04x\tc0: %d\tc1: %d\tx: %d\ty: %d\n"
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"lib: 0x%04x\n",
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exercise,
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ospfd, ospfd_vals.a.c0, ospfd_vals.a.c1, ospfd_vals.x, ospfd_vals.y,
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isisd, isisd_vals.a.c0, isisd_vals.a.c1, isisd_vals.x, isisd_vals.y,
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lib
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);
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/* Investigate reduction phase discrepencies */
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if (ospfd_vals.a.c0 == isisd_vals.a.c0
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&& ospfd_vals.a.c1 == isisd_vals.a.c1) {
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printf ("\n");
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for (i = 0; reducts[i].name != NULL; i++) {
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ospfd = reducts[i].f (&ospfd_vals,
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exercise + sizeof (u_int16_t),
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exercise);
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printf ("%20s: x: %02x, y %02x, checksum 0x%04x\n",
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reducts[i].name, ospfd_vals.x & 0xff, ospfd_vals.y & 0xff, ospfd);
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}
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}
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printf ("\n u_char testdata [] = {\n ");
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for (i = 0; i < exercise; i++) {
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printf ("0x%02x,%s",
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buffer[i],
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(i + 1) % 8 ? " " : "\n ");
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}
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printf ("\n}\n");
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exit (1);
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}
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}
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}
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