4 files changed, 79 insertions, 6 deletions
diff --git a/src/test/fuzz/CMakeLists.txt b/src/test/fuzz/CMakeLists.txt
index 1bf05ee4fb..f65ed62b2d 100644
--- a/src/test/fuzz/CMakeLists.txt
+++ b/src/test/fuzz/CMakeLists.txt
@@ -76,6 +76,7 @@ add_executable(fuzz
   p2p_transport_serialization.cpp
   package_eval.cpp
   parse_hd_keypath.cpp
+  parse_iso8601.cpp
   parse_numbers.cpp
   parse_script.cpp
   parse_univalue.cpp
diff --git a/src/test/fuzz/parse_iso8601.cpp b/src/test/fuzz/parse_iso8601.cpp
new file mode 100644
index 0000000000..7e51f57905
--- /dev/null
+++ b/src/test/fuzz/parse_iso8601.cpp
@@ -0,0 +1,27 @@
+// Copyright (c) 2019-present The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <util/time.h>
+
+#include <cassert>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+FUZZ_TARGET(parse_iso8601)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+
+    const int64_t random_time = fuzzed_data_provider.ConsumeIntegral<int32_t>();
+    const std::string random_string = fuzzed_data_provider.ConsumeRemainingBytesAsString();
+
+    const std::string iso8601_datetime = FormatISO8601DateTime(random_time);
+    (void)FormatISO8601Date(random_time);
+    const int64_t parsed_time_1{ParseISO8601DateTime(iso8601_datetime).value()};
+    assert(parsed_time_1 == random_time);
+
+    (void)ParseISO8601DateTime(random_string);
+}
diff --git a/src/test/fuzz/util.cpp b/src/test/fuzz/util.cpp
index 425b9559a7..d700e5ac97 100644
--- a/src/test/fuzz/util.cpp
+++ b/src/test/fuzz/util.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2021-2022 The Bitcoin Core developers
+// Copyright (c) 2021-present The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -34,8 +34,8 @@ CAmount ConsumeMoney(FuzzedDataProvider& fuzzed_data_provider, const std::option
 int64_t ConsumeTime(FuzzedDataProvider& fuzzed_data_provider, const std::optional<int64_t>& min, const std::optional<int64_t>& max) noexcept
 {
     // Avoid t=0 (1970-01-01T00:00:00Z) since SetMockTime(0) disables mocktime.
-    static const int64_t time_min{946684801}; // 2000-01-01T00:00:01Z
-    static const int64_t time_max{4133980799}; // 2100-12-31T23:59:59Z
+    static const int64_t time_min{ParseISO8601DateTime("2000-01-01T00:00:01Z").value()};
+    static const int64_t time_max{ParseISO8601DateTime("2100-12-31T23:59:59Z").value()};
     return fuzzed_data_provider.ConsumeIntegralInRange<int64_t>(min.value_or(time_min), max.value_or(time_max));
 }
 
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 1624fb8b5b..3f6e5b1b66 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2011-2022 The Bitcoin Core developers
+// Copyright (c) 2011-present The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -323,20 +323,65 @@ BOOST_AUTO_TEST_CASE(util_TrimString)
     BOOST_CHECK_EQUAL(TrimStringView(std::string("\x05\x04\x03\x02\x01\x00", 6), std::string("\x05\x04\x03\x02\x01\x00", 6)), "");
 }
 
+BOOST_AUTO_TEST_CASE(util_ParseISO8601DateTime)
+{
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("1969-12-31T23:59:59Z").value(), -1);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("1970-01-01T00:00:00Z").value(), 0);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("1970-01-01T00:00:01Z").value(), 1);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("2000-01-01T00:00:01Z").value(), 946684801);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("2011-09-30T23:36:17Z").value(), 1317425777);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("2100-12-31T23:59:59Z").value(), 4133980799);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("9999-12-31T23:59:59Z").value(), 253402300799);
+
+    // Accept edge-cases, where the time overflows. They are not produced by
+    // FormatISO8601DateTime, so this can be changed in the future, if needed.
+    // For now, keep compatibility with the previous implementation.
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("2000-01-01T99:00:00Z").value(), 947041200);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("2000-01-01T00:99:00Z").value(), 946690740);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("2000-01-01T00:00:99Z").value(), 946684899);
+    BOOST_CHECK_EQUAL(ParseISO8601DateTime("2000-01-01T99:99:99Z").value(), 947047239);
+
+    // Reject date overflows.
+    BOOST_CHECK(!ParseISO8601DateTime("2000-99-01T00:00:00Z"));
+    BOOST_CHECK(!ParseISO8601DateTime("2000-01-99T00:00:00Z"));
+
+    // Reject out-of-range years
+    BOOST_CHECK(!ParseISO8601DateTime("32768-12-31T23:59:59Z"));
+    BOOST_CHECK(!ParseISO8601DateTime("32767-12-31T23:59:59Z"));
+    BOOST_CHECK(!ParseISO8601DateTime("32767-12-31T00:00:00Z"));
+    BOOST_CHECK(!ParseISO8601DateTime("999-12-31T00:00:00Z"));
+
+    // Reject invalid format
+    const std::string valid{"2000-01-01T00:00:01Z"};
+    BOOST_CHECK(ParseISO8601DateTime(valid).has_value());
+    for (auto mut{0U}; mut < valid.size(); ++mut) {
+        std::string invalid{valid};
+        invalid[mut] = 'a';
+        BOOST_CHECK(!ParseISO8601DateTime(invalid));
+    }
+}
+
 BOOST_AUTO_TEST_CASE(util_FormatISO8601DateTime)
 {
     BOOST_CHECK_EQUAL(FormatISO8601DateTime(971890963199), "32767-12-31T23:59:59Z");
     BOOST_CHECK_EQUAL(FormatISO8601DateTime(971890876800), "32767-12-31T00:00:00Z");
-    BOOST_CHECK_EQUAL(FormatISO8601DateTime(1317425777), "2011-09-30T23:36:17Z");
+
+    BOOST_CHECK_EQUAL(FormatISO8601DateTime(-1), "1969-12-31T23:59:59Z");
     BOOST_CHECK_EQUAL(FormatISO8601DateTime(0), "1970-01-01T00:00:00Z");
+    BOOST_CHECK_EQUAL(FormatISO8601DateTime(1), "1970-01-01T00:00:01Z");
+    BOOST_CHECK_EQUAL(FormatISO8601DateTime(946684801), "2000-01-01T00:00:01Z");
+    BOOST_CHECK_EQUAL(FormatISO8601DateTime(1317425777), "2011-09-30T23:36:17Z");
+    BOOST_CHECK_EQUAL(FormatISO8601DateTime(4133980799), "2100-12-31T23:59:59Z");
+    BOOST_CHECK_EQUAL(FormatISO8601DateTime(253402300799), "9999-12-31T23:59:59Z");
 }
 
 BOOST_AUTO_TEST_CASE(util_FormatISO8601Date)
 {
     BOOST_CHECK_EQUAL(FormatISO8601Date(971890963199), "32767-12-31");
     BOOST_CHECK_EQUAL(FormatISO8601Date(971890876800), "32767-12-31");
-    BOOST_CHECK_EQUAL(FormatISO8601Date(1317425777), "2011-09-30");
+
     BOOST_CHECK_EQUAL(FormatISO8601Date(0), "1970-01-01");
+    BOOST_CHECK_EQUAL(FormatISO8601Date(1317425777), "2011-09-30");
 }
 
 BOOST_AUTO_TEST_CASE(util_FormatMoney)