Merge #21443: fuzz: Implement fuzzed_dns_lookup_function as a lambda

7c8c140 fuzz: Implement fuzzed_dns_lookup_function as lambda (practicalswift)

Pull request description:

  Implement `fuzzed_dns_lookup_function` as a lambda.

  As wisely suggested by MarcoFalke in bitcoin/bitcoin#19415 (comment). Thanks! :)

ACKs for top commit:
  MarcoFalke:
    cr ACK 7c8c140
  vasild:
    ACK 7c8c140

Tree-SHA512: b175f2ad42e9a2be1f769ac677b2872e73ae621731d27e9a24bedadc14d9a6682c7fd1946a0df436d37e7b0cc0d212c1eef69f0409fb975cf9c460cd45f6e4ac

Author: MarcoFalke

src/test/fuzz/netbase_dns_lookup.cpp

@@ -12,27 +12,22 @@
 #include <string>
 #include <vector>
 
-namespace {
-FuzzedDataProvider* fuzzed_data_provider_ptr = nullptr;
-
-std::vector<CNetAddr> fuzzed_dns_lookup_function(const std::string& name, bool allow_lookup)
-{
-    std::vector<CNetAddr> resolved_addresses;
-    while (fuzzed_data_provider_ptr->ConsumeBool()) {
-        resolved_addresses.push_back(ConsumeNetAddr(*fuzzed_data_provider_ptr));
-    }
-    return resolved_addresses;
-}
-} // namespace
-
 FUZZ_TARGET(netbase_dns_lookup)
 {
     FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
-    fuzzed_data_provider_ptr = &fuzzed_data_provider;
     const std::string name = fuzzed_data_provider.ConsumeRandomLengthString(512);
     const unsigned int max_results = fuzzed_data_provider.ConsumeIntegral<unsigned int>();
     const bool allow_lookup = fuzzed_data_provider.ConsumeBool();
     const int default_port = fuzzed_data_provider.ConsumeIntegral<int>();
+
+    auto fuzzed_dns_lookup_function = [&](const std::string&, bool) {
+        std::vector<CNetAddr> resolved_addresses;
+        while (fuzzed_data_provider.ConsumeBool()) {
+            resolved_addresses.push_back(ConsumeNetAddr(fuzzed_data_provider));
+        }
+        return resolved_addresses;
+    };
+
     {
         std::vector<CNetAddr> resolved_addresses;
         if (LookupHost(name, resolved_addresses, max_results, allow_lookup, fuzzed_dns_lookup_function)) {
@@ -73,5 +68,4 @@ FUZZ_TARGET(netbase_dns_lookup)
             assert(resolved_subnet.IsValid());
         }
     }
-    fuzzed_data_provider_ptr = nullptr;
 }