tests: Add fuzzing harness for AS-mapping (asmap)

src/test/fuzz/asmap.cpp

@@ -0,0 +1,28 @@
+// Copyright (c) 2020 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 <netaddress.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+
+#include <cstdint>
+#include <vector>
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+    const Network network = fuzzed_data_provider.PickValueInArray({NET_IPV4, NET_IPV6});
+    if (fuzzed_data_provider.remaining_bytes() < 16) {
+        return;
+    }
+    CNetAddr net_addr;
+    net_addr.SetRaw(network, fuzzed_data_provider.ConsumeBytes<uint8_t>(16).data());
+    std::vector<bool> asmap;
+    for (const char cur_byte : fuzzed_data_provider.ConsumeRemainingBytes<char>()) {
+        for (int bit = 0; bit < 8; ++bit) {
+            asmap.push_back((cur_byte >> bit) & 1);
+        }
+    }
+    (void)net_addr.GetMappedAS(asmap);
+}