misc: fix UB in CPID hashing

src/gridcoin/cpid.h

@@ -454,9 +454,9 @@ namespace std {
 //! This enables the use of GRC::Cpid as a key in a std::unordered_map object.
 //!
 //! CONSENSUS: Don't use the hash produced by this routine (or by any std::hash
-//! specialization) in protocol-specific implementations. It ignores endianness
-//! and outputs a value with a chance of collision probably too great for usage
-//! besides the intended local look-up functionality.
+//! specialization) in protocol-specific implementations. It outputs a value
+//! with a chance of collision probably too great for usage besides the intended
+//! local look-up functionality.
 //!
 template<>
 struct hash<GRC::Cpid>
@@ -473,8 +473,16 @@ struct hash<GRC::Cpid>
         // Just convert the CPID into a value that we can store in a size_t
         // object. CPIDs are already unique identifiers.
         //
-        return *reinterpret_cast<const uint64_t*>(cpid.Raw().data())
-            + *reinterpret_cast<const uint64_t*>(cpid.Raw().data() + 8);
+        const auto& data = cpid.Raw();
+        size_t ret = ((size_t)(data[0] & 255)       | (size_t)(data[1] & 255) << 8 |
+                      (size_t)(data[2] & 255) << 16 | (size_t)(data[3] & 255) << 24);
+
+        if (sizeof(size_t) == 8) {
+            ret |= ((size_t)(data[4] & 255) << 32 | (size_t)(data[5] & 255) << 40 |
+                    (size_t)(data[6] & 255) << 48 | (size_t)(data[7] & 255) << 56);
+        }
+
+        return ret;
     }
 };
 }

src/test/gridcoin/cpid_tests.cpp

@@ -239,21 +239,6 @@ BOOST_AUTO_TEST_CASE(it_deserializes_from_a_stream)
     BOOST_CHECK(bytes == expected);
 }
 
-BOOST_AUTO_TEST_CASE(it_is_hashable_to_key_a_lookup_map)
-{
-    GRC::Cpid cpid(std::vector<unsigned char> {
-        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
-        0x08, 0x09, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15,
-    });
-
-    std::hash<GRC::Cpid> hasher;
-
-    // CPID halves, little endian
-    const size_t expected = static_cast<size_t>(0x0706050403020100ull + 0x1514131211100908ull);
-
-    BOOST_CHECK_EQUAL(hasher(cpid), expected);
-}
-
 BOOST_AUTO_TEST_SUITE_END()
 
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