change peer priority to use crc32c instead of sha1

src/kademlia/node_id.cpp

@@ -134,6 +134,9 @@ node_id generate_id_impl(address const& ip_, boost::uint32_t r)
 	ip[0] |= (r & 0x7) << 5;
 
 	// this is the crc32c (Castagnoli) polynomial
+	// TODO: 2 this could be optimized if SSE 4.2 is
+	// available. It could also be optimized given
+	// that we have a fixed length
 	boost::crc_optimal<32, 0x1EDC6F41, 0xFFFFFFFF, 0xFFFFFFFF, true, true> crc;
 	crc.process_block(ip, ip + num_octets);
 	boost::uint32_t c = crc.checksum();

src/policy.cpp

@@ -38,6 +38,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include <boost/bind.hpp>
 #include <boost/utility.hpp>
+#include <boost/crc.hpp>
 
 #ifdef _MSC_VER
 #pragma warning(pop)
@@ -150,7 +151,12 @@ namespace libtorrent
 
 		using std::swap;
 
-		hasher h;
+		// this is the crc32c (Castagnoli) polynomial
+		// TODO: 2 this could be optimized if SSE 4.2 is
+		// available. It could also be optimized given
+		// that we have a fixed length
+		boost::crc_optimal<32, 0x1EDC6F41, 0xFFFFFFFF, 0xFFFFFFFF, true, true> crc;
+
 		if (e1.address() == e2.address())
 		{
 			if (e1.port() > e2.port())
@@ -158,7 +164,7 @@ namespace libtorrent
 			boost::uint16_t p[2];
 			p[0] = htons(e1.port());
 			p[1] = htons(e2.port());
-			h.update((char const*)&p[0], 4);
+			crc.process_block((char const*)&p[0], (char const*)&p[2]);
 		}
 #if TORRENT_USE_IPV6
 		else if (e1.address().is_v6())
@@ -176,8 +182,9 @@ namespace libtorrent
 				: memcmp(&b1[0], &b2[0], 6) ? 1 : 2;
 			apply_mask(&b1[0], v6mask[mask], 8);
 			apply_mask(&b2[0], v6mask[mask], 8);
-			h.update((char const*)&b1[0], b1.size());
-			h.update((char const*)&b2[0], b2.size());
+
+			crc.process_block((char const*)&b1[0], (char const*)&b1[16]);
+			crc.process_block((char const*)&b2[0], (char const*)&b2[16]);
 		}
 #endif
 		else
@@ -195,17 +202,14 @@ namespace libtorrent
 				: memcmp(&b1[0], &b2[0], 3) ? 1 : 2;
 			apply_mask(&b1[0], v4mask[mask], 4);
 			apply_mask(&b2[0], v4mask[mask], 4);
-			h.update((char const*)&b1[0], b1.size());
-			h.update((char const*)&b2[0], b2.size());
+
+			crc.process_block((char const*)&b1[0], (char const*)&b1[4]);
+			crc.process_block((char const*)&b2[0], (char const*)&b2[4]);
 		}
 
-		boost::uint32_t ret;
-		sha1_hash digest = h.final();
-		memcpy(&ret, &digest[0], 4);
-		return ntohl(ret);
+		return crc.checksum();
 	}
 
-
 	// returns the rank of a peer's source. We have an affinity
 	// to connecting to peers with higher rank. This is to avoid
 	// problems when our peer list is diluted by stale peers from
@@ -1899,7 +1903,7 @@ namespace libtorrent
 	// TOOD: pass in both an IPv6 and IPv4 address here
 	boost::uint32_t policy::peer::rank(external_ip const& external, int external_port) const
 	{
-//TODO: how do we deal with our external address changing? Pass in a force-update maybe? and keep a version number in policy
+//TODO 3: how do we deal with our external address changing? Pass in a force-update maybe? and keep a version number in policy
 		if (peer_rank == 0)
 			peer_rank = peer_priority(
 				tcp::endpoint(external.external_address(this->address()), external_port)

test/test_peer_priority.cpp

@@ -33,6 +33,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/policy.hpp"
 #include "libtorrent/hasher.hpp"
 #include "libtorrent/broadcast_socket.hpp" // for supports_ipv6()
+#include <boost/crc.hpp>
 
 #include "test.hpp"
 
@@ -40,12 +41,9 @@ using namespace libtorrent;
 
 boost::uint32_t hash_buffer(char const* buf, int len)
 {
-	hasher h;
-	h.update(buf, len);
-	sha1_hash digest = h.final();
-	boost::uint32_t ret;
-	memcpy(&ret, &digest[0], 4);
-	return ntohl(ret);
+	boost::crc_optimal<32, 0x1EDC6F41, 0xFFFFFFFF, 0xFFFFFFFF, true, true> crc;
+	crc.process_block(buf, buf + len);
+	return crc.checksum();
 }
 
 int test_main()