From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) by passt.top (Postfix) with ESMTPS id 14BA45A026F for ; Thu, 28 Sep 2023 03:21:11 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=201602; t=1695864065; bh=7aKLOAlHCLHhkRE7VIqDCRWMjQpqSIZrMEaXVsGeKFs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H+L+2Et3feU1IdUZrQpb2ZE9QZZipP+mp36CBQYIiOL4jPmQV24+VQnv+UpZfKzgo wIzuNub2iysF8/UKUN7GgL9FcI3uhBm15N3w1oJLkmeJsd9h92phxkNbkF0w8LMuAs sBctYuJ7B8mJ6IGCzKbHL/EMpdQQ7/VwVoU8lw1s= Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4RwwfS753Mz4xRn; Thu, 28 Sep 2023 11:21:04 +1000 (AEST) From: David Gibson To: Stefano Brivio , passt-dev@passt.top Subject: [PATCH v2 04/10] siphash: Clean up hash finalisation with posthash_final() function Date: Thu, 28 Sep 2023 11:20:56 +1000 Message-ID: <20230928012102.1446180-5-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230928012102.1446180-1-david@gibson.dropbear.id.au> References: <20230928012102.1446180-1-david@gibson.dropbear.id.au> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: BXJ4DVXDBWQVKBL7GMYA6B7NJY46LZYE X-Message-ID-Hash: BXJ4DVXDBWQVKBL7GMYA6B7NJY46LZYE X-MailFrom: dgibson@gandalf.ozlabs.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson X-Mailman-Version: 3.3.8 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: The POSTAMBLE macro implements the finalisation steps of SipHash. It relies on some variables in the environment, including returning the final hash value that way. That isn't great hygeine. In addition the PREAMBLE macro takes a length parameter which is used only to initialize the 'b' value that's not used until the finalisation and is also sometimes modified in a non-obvious way by the callers. The 'b' value is always composed from the total length of the hash input plus up to 7 bytes of "tail" data - that is the remainder of the hash input after a multiple of 8 bytes has been consumed. Simplify all this by replacing the POSTAMBLE macro with a siphash_final() function which takes the length and tail data as parameters and returns the final hash value. Signed-off-by: David Gibson --- siphash.c | 58 +++++++++++++++++++++++++++---------------------------- 1 file changed, 28 insertions(+), 30 deletions(-) diff --git a/siphash.c b/siphash.c index 716ab62..ec39793 100644 --- a/siphash.c +++ b/siphash.c @@ -51,16 +51,16 @@ * */ +#include #include #include "siphash.h" #define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b)))) -#define PREAMBLE(len) \ +#define PREAMBLE \ uint64_t v[4] = { 0x736f6d6570736575ULL, 0x646f72616e646f6dULL, \ 0x6c7967656e657261ULL, 0x7465646279746573ULL }; \ - uint64_t b = (uint64_t)(len) << 56; \ int __i; \ \ do { \ @@ -103,13 +103,21 @@ static inline void siphash_feed(uint64_t *v, uint64_t in) v[0] ^= in; } -#define POSTAMBLE \ - do { \ - siphash_feed(v, b); \ - v[2] ^= 0xff; \ - sipround(v, 4); \ - b = (v[0] ^ v[1]) ^ (v[2] ^ v[3]); \ - } while (0) +/** + * siphash_final - Finalize SipHash calculations + * @v: siphash state (4 x 64-bit integers) + * @len: Total length of input data + * @tail: Final data for the hash (<= 7 bytes) + */ +static inline uint64_t siphash_final(uint64_t *v, size_t len, uint64_t tail) +{ + uint64_t b = (uint64_t)(len) << 56 | tail; + + siphash_feed(v, b); + v[2] ^= 0xff; + sipround(v, 4); + return v[0] ^ v[1] ^ v[2] ^ v[3]; +} /** * siphash_8b() - Table index or timestamp offset for TCP over IPv4 (8 bytes in) @@ -132,11 +140,11 @@ __attribute__((optimize("-fno-strict-aliasing"))) /* cppcheck-suppress unusedFunction */ uint64_t siphash_8b(const uint8_t *in, const uint64_t *k) { - PREAMBLE(8); + PREAMBLE; siphash_feed(v, *(uint64_t *)in); - POSTAMBLE; - return b; + + return siphash_final(v, 8, 0); } /** @@ -153,12 +161,10 @@ uint64_t siphash_12b(const uint8_t *in, const uint64_t *k) { uint32_t *in32 = (uint32_t *)in; - PREAMBLE(12); + PREAMBLE; siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32); - b |= *(in32 + 2); - POSTAMBLE; - return b; + return siphash_final(v, 12, *(in32 + 2)); } /** @@ -175,15 +181,12 @@ uint64_t siphash_20b(const uint8_t *in, const uint64_t *k) uint32_t *in32 = (uint32_t *)in; int i; - PREAMBLE(20); + PREAMBLE; for (i = 0; i < 2; i++, in32 += 2) siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32); - b |= *in32; - POSTAMBLE; - - return b; + return siphash_final(v, 20, *in32); } /** @@ -201,14 +204,12 @@ uint64_t siphash_32b(const uint8_t *in, const uint64_t *k) uint64_t *in64 = (uint64_t *)in; int i; - PREAMBLE(32); + PREAMBLE; for (i = 0; i < 4; i++, in64++) siphash_feed(v, *in64); - POSTAMBLE; - - return b; + return siphash_final(v, 32, 0); } /** @@ -225,13 +226,10 @@ uint64_t siphash_36b(const uint8_t *in, const uint64_t *k) uint32_t *in32 = (uint32_t *)in; int i; - PREAMBLE(36); + PREAMBLE; for (i = 0; i < 4; i++, in32 += 2) siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32); - b |= *in32; - POSTAMBLE; - - return b; + return siphash_final(v, 36, *in32); } -- 2.41.0