1 files changed, 254 insertions, 0 deletions
diff --git a/src/libutp/utp_utils.cpp b/src/libutp/utp_utils.cpp
new file mode 100644
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+++ b/src/libutp/utp_utils.cpp
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+/*
+ * Copyright (c) 2010-2013 BitTorrent, Inc.
+ *
+ * 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.
+ */
+
+#include <stdlib.h>
+#include <assert.h>
+#include "utp.h"
+#include "utp_types.h"
+
+#ifdef WIN32
+	#define WIN32_LEAN_AND_MEAN
+	#include <windows.h>
+	#include <winsock2.h>
+	#include <ws2tcpip.h>
+#else //!WIN32
+	#include <time.h>
+	#include <sys/time.h>		// Linux needs both time.h and sys/time.h
+#endif
+
+#if defined(__APPLE__)
+	#include <mach/mach_time.h>
+#endif
+
+#include "utp_utils.h"
+
+#ifdef WIN32
+
+typedef ULONGLONG (WINAPI GetTickCount64Proc)(void);
+static GetTickCount64Proc *pt2GetTickCount64;
+static GetTickCount64Proc *pt2RealGetTickCount;
+
+static uint64 startPerformanceCounter;
+static uint64 startGetTickCount;
+// MSVC 6 standard doesn't like division with uint64s
+static double counterPerMicrosecond;
+
+static uint64 UTGetTickCount64()
+{
+	if (pt2GetTickCount64) {
+		return pt2GetTickCount64();
+	}
+	if (pt2RealGetTickCount) {
+		uint64 v = pt2RealGetTickCount();
+		// fix return value from GetTickCount
+		return (DWORD)v | ((v >> 0x18) & 0xFFFFFFFF00000000);
+	}
+	return (uint64)GetTickCount();
+}
+
+static void Time_Initialize()
+{
+	HMODULE kernel32 = GetModuleHandleA("kernel32.dll");
+	pt2GetTickCount64 = (GetTickCount64Proc*)GetProcAddress(kernel32, "GetTickCount64");
+	// not a typo. GetTickCount actually returns 64 bits
+	pt2RealGetTickCount = (GetTickCount64Proc*)GetProcAddress(kernel32, "GetTickCount");
+
+	uint64 frequency;
+	QueryPerformanceCounter((LARGE_INTEGER*)&startPerformanceCounter);
+	QueryPerformanceFrequency((LARGE_INTEGER*)&frequency);
+	counterPerMicrosecond = (double)frequency / 1000000.0f;
+	startGetTickCount = UTGetTickCount64();
+}
+
+static int64 abs64(int64 x) { return x < 0 ? -x : x; }
+
+static uint64 __GetMicroseconds()
+{
+	static bool time_init = false;
+	if (!time_init) {
+		time_init = true;
+		Time_Initialize();
+	}
+
+	uint64 counter;
+	uint64 tick;
+
+	QueryPerformanceCounter((LARGE_INTEGER*) &counter);
+	tick = UTGetTickCount64();
+
+	// unfortunately, QueryPerformanceCounter is not guaranteed
+	// to be monotonic. Make it so.
+	int64 ret = (int64)(((int64)counter - (int64)startPerformanceCounter) / counterPerMicrosecond);
+	// if the QPC clock leaps more than one second off GetTickCount64()
+	// something is seriously fishy. Adjust QPC to stay monotonic
+	int64 tick_diff = tick - startGetTickCount;
+	if (abs64(ret / 100000 - tick_diff / 100) > 10) {
+		startPerformanceCounter -= (uint64)((int64)(tick_diff * 1000 - ret) * counterPerMicrosecond);
+		ret = (int64)((counter - startPerformanceCounter) / counterPerMicrosecond);
+	}
+	return ret;
+}
+
+static inline uint64 UTP_GetMilliseconds()
+{
+	return GetTickCount();
+}
+
+#else //!WIN32
+
+static inline uint64 UTP_GetMicroseconds(void);
+static inline uint64 UTP_GetMilliseconds()
+{
+	return UTP_GetMicroseconds() / 1000;
+}
+
+#if defined(__APPLE__)
+
+static uint64 __GetMicroseconds()
+{
+	// http://developer.apple.com/mac/library/qa/qa2004/qa1398.html
+	// http://www.macresearch.org/tutorial_performance_and_time
+	static mach_timebase_info_data_t sTimebaseInfo;
+	static uint64_t start_tick = 0;
+	uint64_t tick;
+	// Returns a counter in some fraction of a nanoseconds
+	tick = mach_absolute_time();
+	if (sTimebaseInfo.denom == 0) {
+		// Get the timer ratio to convert mach_absolute_time to nanoseconds
+		mach_timebase_info(&sTimebaseInfo);
+		start_tick = tick;
+	}
+	// Calculate the elapsed time, convert it to microseconds and return it.
+	return ((tick - start_tick) * sTimebaseInfo.numer) / (sTimebaseInfo.denom * 1000);
+}
+
+#else // !__APPLE__
+
+#if ! (defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0 && defined(CLOCK_MONOTONIC))
+    #pragma message ("Using non-monotonic function gettimeofday() in UTP_GetMicroseconds()")
+#endif
+
+/* Unfortunately, #ifdef CLOCK_MONOTONIC is not enough to make sure that
+   POSIX clocks work -- we could be running a recent libc with an ancient
+   kernel (think OpenWRT). -- jch */
+
+static uint64_t __GetMicroseconds()
+{
+	struct timeval tv;
+
+	#if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0 && defined(CLOCK_MONOTONIC)
+		static int have_posix_clocks = -1;
+		int rc;
+
+		if (have_posix_clocks < 0) {
+			struct timespec ts;
+			rc = clock_gettime(CLOCK_MONOTONIC, &ts);
+			if (rc < 0) {
+				have_posix_clocks = 0;
+			} else {
+				have_posix_clocks = 1;
+			}
+		}
+
+		if (have_posix_clocks) {
+			struct timespec ts;
+			rc = clock_gettime(CLOCK_MONOTONIC, &ts);
+			return uint64(ts.tv_sec) * 1000000 + uint64(ts.tv_nsec) / 1000;
+		}
+	#endif
+
+	gettimeofday(&tv, NULL);
+	return uint64(tv.tv_sec) * 1000000 + tv.tv_usec;
+}
+
+#endif //!__APPLE__
+
+#endif //!WIN32
+
+/*
+ * Whew.  Okay.  After that #ifdef maze above, we now know we have a working
+ * __GetMicroseconds() implementation on all platforms.
+ * 
+ * Because there are a number of assertions in libutp that will cause a crash
+ * if monotonic time isn't monotonic, now apply some safety checks.  While in
+ * principle we're already protecting ourselves in cases where non-monotonic
+ * time is likely to happen, this protects all versions.
+ */
+
+static inline uint64 UTP_GetMicroseconds()
+{
+	static uint64 offset = 0, previous = 0;
+
+	uint64 now = __GetMicroseconds() + offset;
+	if (previous > now) {
+		/* Eek! */
+		offset += previous - now;
+		now = previous;
+	}
+	previous = now;
+	return now;
+}
+
+#define ETHERNET_MTU 1500
+#define IPV4_HEADER_SIZE 20
+#define IPV6_HEADER_SIZE 40
+#define UDP_HEADER_SIZE 8
+#define GRE_HEADER_SIZE 24
+#define PPPOE_HEADER_SIZE 8
+#define MPPE_HEADER_SIZE 2
+// packets have been observed in the wild that were fragmented
+// with a payload of 1416 for the first fragment
+// There are reports of routers that have MTU sizes as small as 1392
+#define FUDGE_HEADER_SIZE 36
+#define TEREDO_MTU 1280
+
+#define UDP_IPV4_OVERHEAD (IPV4_HEADER_SIZE + UDP_HEADER_SIZE)
+#define UDP_IPV6_OVERHEAD (IPV6_HEADER_SIZE + UDP_HEADER_SIZE)
+#define UDP_TEREDO_OVERHEAD (UDP_IPV4_OVERHEAD + UDP_IPV6_OVERHEAD)
+
+#define UDP_IPV4_MTU (ETHERNET_MTU - IPV4_HEADER_SIZE - UDP_HEADER_SIZE - GRE_HEADER_SIZE - PPPOE_HEADER_SIZE - MPPE_HEADER_SIZE - FUDGE_HEADER_SIZE)
+#define UDP_IPV6_MTU (ETHERNET_MTU - IPV6_HEADER_SIZE - UDP_HEADER_SIZE - GRE_HEADER_SIZE - PPPOE_HEADER_SIZE - MPPE_HEADER_SIZE - FUDGE_HEADER_SIZE)
+#define UDP_TEREDO_MTU (TEREDO_MTU - IPV6_HEADER_SIZE - UDP_HEADER_SIZE)
+
+uint64 utp_default_get_udp_mtu(utp_callback_arguments *args) {
+	// Since we don't know the local address of the interface,
+	// be conservative and assume all IPv6 connections are Teredo.
+	return (args->address->sa_family == AF_INET6) ? UDP_TEREDO_MTU : UDP_IPV4_MTU;
+}
+
+uint64 utp_default_get_udp_overhead(utp_callback_arguments *args) {
+	// Since we don't know the local address of the interface,
+	// be conservative and assume all IPv6 connections are Teredo.
+	return (args->address->sa_family == AF_INET6) ? UDP_TEREDO_OVERHEAD : UDP_IPV4_OVERHEAD;
+}
+
+uint64 utp_default_get_random(utp_callback_arguments * /*args*/) {
+	return rand();
+}
+
+uint64 utp_default_get_milliseconds(utp_callback_arguments * /*args*/) {
+	return UTP_GetMilliseconds();
+}
+
+uint64 utp_default_get_microseconds(utp_callback_arguments * /*args*/) {
+	return UTP_GetMicroseconds();
+}