1 files changed, 173 insertions, 0 deletions

diff --git a/src/lib/util/crypto_crc.c b/src/lib/util/crypto_crc.c
new file mode 100644
index 000000000..f93b5b0b3
--- /dev/null
+++ b/src/lib/util/crypto_crc.c
@@ -0,0 +1,173 @@
+/*
+     This file is part of GNUnet.
+     Copyright (C) 2001, 2002, 2003, 2004, 2006 GNUnet e.V.
+
+     GNUnet is free software: you can redistribute it and/or modify it
+     under the terms of the GNU Affero General Public License as published
+     by the Free Software Foundation, either version 3 of the License,
+     or (at your option) any later version.
+
+     GNUnet is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     Affero General Public License for more details.
+
+     You should have received a copy of the GNU Affero General Public License
+     along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+     SPDX-License-Identifier: AGPL3.0-or-later
+
+     For the actual CRC-32 code:
+     Copyright abandoned; this code is in the public domain.
+     Provided to GNUnet by peter@horizon.com
+ */
+
+/**
+ * @file util/crypto_crc.c
+ * @brief implementation of CRC16 and CRC32
+ * @author Christian Grothoff
+ */
+
+#include "platform.h"
+#include "gnunet_util_lib.h"
+
+#define LOG(kind, ...) GNUNET_log_from (kind, "util-crypto-crc", __VA_ARGS__)
+
+/* Avoid wasting space on 8-byte longs. */
+#if UINT_MAX >= 0xffffffff
+typedef unsigned int GNUNET_uLong;
+#elif ULONG_MAX >= 0xffffffff
+typedef unsigned long GNUNET_uLong;
+#else
+#error This compiler is not ANSI-compliant!
+#endif
+
+#define Z_NULL  0
+
+
+#define POLYNOMIAL (GNUNET_uLong) 0xedb88320
+static GNUNET_uLong crc_table[256];
+
+/*
+ * This routine writes each crc_table entry exactly once,
+ * with the correct final value.  Thus, it is safe to call
+ * even on a table that someone else is using concurrently.
+ */
+static void
+crc_init ()
+{
+  static int once;
+  GNUNET_uLong h = 1;
+
+  if (once)
+    return;
+  once = 1;
+  crc_table[0] = 0;
+  for (unsigned int i = 128; i; i >>= 1)
+  {
+    h = (h >> 1) ^ ((h & 1) ? POLYNOMIAL : 0);
+    /* h is now crc_table[i] */
+    for (unsigned int j = 0; j < 256; j += 2 * i)
+      crc_table[i + j] = crc_table[j] ^ h;
+  }
+}
+
+
+/*
+ * This computes the standard preset and inverted CRC, as used
+ * by most networking standards.  Start by passing in an initial
+ * chaining value of 0, and then pass in the return value from the
+ * previous crc32() call.  The final return value is the CRC.
+ * Note that this is a little-endian CRC, which is best used with
+ * data transmitted lsbit-first, and it should, itself, be appended
+ * to data in little-endian byte and bit order to preserve the
+ * property of detecting all burst errors of length 32 bits or less.
+ */
+static GNUNET_uLong
+gn_crc32 (GNUNET_uLong crc, const char *buf, size_t len)
+{
+  crc_init ();
+  GNUNET_assert (crc_table[255] != 0);
+  crc ^= 0xffffffff;
+  while (len--)
+    crc = (crc >> 8) ^ crc_table[(crc ^ *buf++) & 0xff];
+  return crc ^ 0xffffffff;
+}
+
+
+int32_t
+GNUNET_CRYPTO_crc32_n (const void *buf, size_t len)
+{
+  GNUNET_uLong crc;
+
+  crc = gn_crc32 (0L, Z_NULL, 0);
+  crc = gn_crc32 (crc, (char *) buf, len);
+  return crc;
+}
+
+
+uint32_t
+GNUNET_CRYPTO_crc16_step (uint32_t sum, const void *buf, size_t len)
+{
+  const uint16_t *hdr = buf;
+
+  for (; len >= 2; len -= 2)
+    sum += *(hdr++);
+  if (len == 1)
+    sum += ntohs(*((uint8_t *)hdr) << 8);
+  return sum;
+}
+
+
+uint16_t
+GNUNET_CRYPTO_crc16_finish (uint32_t sum)
+{
+  sum = (sum >> 16) + (sum & 0xFFFF);
+  sum += (sum >> 16);
+
+  return ~sum;
+}
+
+
+uint16_t
+GNUNET_CRYPTO_crc16_n (const void *buf, size_t len)
+{
+  const uint16_t *hdr = buf;
+  uint32_t sum = GNUNET_CRYPTO_crc16_step (0, hdr, len);
+
+  return GNUNET_CRYPTO_crc16_finish (sum);
+}
+
+
+/**
+ * @ingroup hash
+ * Calculate the checksum of a buffer in one step.
+ *
+ * @param buf buffer to calculate CRC over
+ * @param len number of bytes in @a buf
+ * @return crc8 value
+ */
+uint8_t
+GNUNET_CRYPTO_crc8_n (const void *buf,
+                      size_t len)
+{
+  const uint8_t *data = buf;
+  unsigned int crc = 0;
+  int i;
+  int j;
+
+  for (j = len; 0 != j; j--)
+  {
+    crc ^= (*data++ << 8);
+    for (i = 8; 0 != i; i--)
+    {
+      if (0 != (crc & 0x8000))
+        crc ^= (0x1070 << 3);
+      crc <<= 1;
+    }
+  }
+  return (uint8_t) (crc >> 8);
+}
+
+
+/* end of crypto_crc.c */