Raw import of Marek Majkowski's cisphash.c

siphash is a hash function designed for producing hard-to-predict
64-bit outputs from short inputs and a 128-bit key.  It's chosen for
security and speed.

See https://131002.net/siphash/ for more information on siphash.

Source: https://github.com/majek/csiphash/

LICENSE

@@ -100,6 +100,29 @@ src/ext/tor_queue.h is licensed under the following license:
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
 
+===============================================================================
+src/ext/csiphash.c is licensed under the following license:
+
+ Copyright (c) 2013  Marek Majkowski <marek@popcount.org>
+
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice shall be included in
+ all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ THE SOFTWARE.
+
 ===============================================================================
 src/config/geoip is licensed under the following license:
 

src/ext/csiphash.c

+/* <MIT License>
+ Copyright (c) 2013  Marek Majkowski <marek@popcount.org>
+
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice shall be included in
+ all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ THE SOFTWARE.
+ </MIT License>
+
+ Original location:
+    https://github.com/majek/csiphash/
+
+ Solution inspired by code from:
+    Samuel Neves (supercop/crypto_auth/siphash24/little)
+    djb (supercop/crypto_auth/siphash24/little2)
+    Jean-Philippe Aumasson (https://131002.net/siphash/siphash24.c)
+*/
+
+#include <stdint.h>
+
+#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
+	__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#  define _le64toh(x) ((uint64_t)(x))
+#elif defined(_WIN32)
+/* Windows is always little endian, unless you're on xbox360
+   http://msdn.microsoft.com/en-us/library/b0084kay(v=vs.80).aspx */
+#  define _le64toh(x) ((uint64_t)(x))
+#elif defined(__APPLE__)
+#  include <libkern/OSByteOrder.h>
+#  define _le64toh(x) OSSwapLittleToHostInt64(x)
+#else
+
+/* See: http://sourceforge.net/p/predef/wiki/Endianness/ */
+#  if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__)
+#    include <sys/endian.h>
+#  else
+#    include <endian.h>
+#  endif
+#  if defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && \
+	__BYTE_ORDER == __LITTLE_ENDIAN
+#    define _le64toh(x) ((uint64_t)(x))
+#  else
+#    define _le64toh(x) le64toh(x)
+#  endif
+
+#endif
+
+
+#define ROTATE(x, b) (uint64_t)( ((x) << (b)) | ( (x) >> (64 - (b))) )
+
+#define HALF_ROUND(a,b,c,d,s,t)			\
+	a += b; c += d;				\
+	b = ROTATE(b, s) ^ a;			\
+	d = ROTATE(d, t) ^ c;			\
+	a = ROTATE(a, 32);
+
+#define DOUBLE_ROUND(v0,v1,v2,v3)		\
+	HALF_ROUND(v0,v1,v2,v3,13,16);		\
+	HALF_ROUND(v2,v1,v0,v3,17,21);		\
+	HALF_ROUND(v0,v1,v2,v3,13,16);		\
+	HALF_ROUND(v2,v1,v0,v3,17,21);
+
+
+uint64_t siphash24(const void *src, unsigned long src_sz, const char key[16]) {
+	const uint64_t *_key = (uint64_t *)key;
+	uint64_t k0 = _le64toh(_key[0]);
+	uint64_t k1 = _le64toh(_key[1]);
+	uint64_t b = (uint64_t)src_sz << 56;
+	const uint64_t *in = (uint64_t*)src;
+
+	uint64_t v0 = k0 ^ 0x736f6d6570736575ULL;
+	uint64_t v1 = k1 ^ 0x646f72616e646f6dULL;
+	uint64_t v2 = k0 ^ 0x6c7967656e657261ULL;
+	uint64_t v3 = k1 ^ 0x7465646279746573ULL;
+
+	while (src_sz >= 8) {
+		uint64_t mi = _le64toh(*in);
+		in += 1; src_sz -= 8;
+		v3 ^= mi;
+		DOUBLE_ROUND(v0,v1,v2,v3);
+		v0 ^= mi;
+	}
+
+	uint64_t t = 0; uint8_t *pt = (uint8_t *)&t; uint8_t *m = (uint8_t *)in;
+	switch (src_sz) {
+	case 7: pt[6] = m[6];
+	case 6: pt[5] = m[5];
+	case 5: pt[4] = m[4];
+	case 4: *((uint32_t*)&pt[0]) = *((uint32_t*)&m[0]); break;
+	case 3: pt[2] = m[2];
+	case 2: pt[1] = m[1];
+	case 1: pt[0] = m[0];
+	}
+	b |= _le64toh(t);
+
+	v3 ^= b;
+	DOUBLE_ROUND(v0,v1,v2,v3);
+	v0 ^= b; v2 ^= 0xff;
+	DOUBLE_ROUND(v0,v1,v2,v3);
+	DOUBLE_ROUND(v0,v1,v2,v3);
+	return (v0 ^ v1) ^ (v2 ^ v3);
+}