From 7b11cd3a11c939c957eeff71af7feddaa86e7f82 Mon Sep 17 00:00:00 2001
From: "Daniel J. Hofmann" <daniel@trvx.org>
Date: Thu, 22 Dec 2016 12:56:58 +0100
Subject: [PATCH] Makes Types in Squared Dist Calculation Explicit, see #3483.

---
 src/util/coordinate_calculation.cpp        | 11 ++++++++---
 unit_tests/util/coordinate_calculation.cpp | 14 ++++++++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/util/coordinate_calculation.cpp b/src/util/coordinate_calculation.cpp
index 3ba1f22a3..cfc2846ce 100644
--- a/src/util/coordinate_calculation.cpp
+++ b/src/util/coordinate_calculation.cpp
@@ -21,10 +21,15 @@ namespace coordinate_calculation
 // Does not project the coordinates!
 std::uint64_t squaredEuclideanDistance(const Coordinate lhs, const Coordinate rhs)
 {
-    const std::uint64_t dx = static_cast<std::int32_t>(lhs.lon - rhs.lon);
-    const std::uint64_t dy = static_cast<std::int32_t>(lhs.lat - rhs.lat);
+    std::int64_t d_lon = static_cast<std::int32_t>(lhs.lon - rhs.lon);
+    std::int64_t d_lat = static_cast<std::int32_t>(lhs.lat - rhs.lat);
 
-    return dx * dx + dy * dy;
+    std::int64_t sq_lon = d_lon * d_lon;
+    std::int64_t sq_lat = d_lat * d_lat;
+
+    std::uint64_t result = static_cast<std::uint64_t>(sq_lon + sq_lat);
+
+    return result;
 }
 
 double haversineDistance(const Coordinate coordinate_1, const Coordinate coordinate_2)
diff --git a/unit_tests/util/coordinate_calculation.cpp b/unit_tests/util/coordinate_calculation.cpp
index 3bea3eb86..83fbb9e2c 100644
--- a/unit_tests/util/coordinate_calculation.cpp
+++ b/unit_tests/util/coordinate_calculation.cpp
@@ -311,4 +311,18 @@ BOOST_AUTO_TEST_CASE(circleCenter)
     BOOST_CHECK(!result);
 }
 
+// For overflow issue #3483, introduced in 68ee4eab61548. Run with -fsanitize=integer.
+BOOST_AUTO_TEST_CASE(squaredEuclideanDistance)
+{
+    // Overflow happens when left hand side values are smaller than right hand side values,
+    // then `lhs - rhs` will be negative but stored in a uint64_t (wraps around).
+
+    Coordinate lhs(FloatLongitude{-180}, FloatLatitude{-90});
+    Coordinate rhs(FloatLongitude{180}, FloatLatitude{90});
+
+    const auto result = coordinate_calculation::squaredEuclideanDistance(lhs, rhs);
+
+    BOOST_CHECK_EQUAL(result, 162000000000000000ull);
+}
+
 BOOST_AUTO_TEST_SUITE_END()