addrman: Introduce a test-only function to lookup addresses

Co-Authored-By: Martin Zumsande <mzumsande@gmail.com>

src/addrman.h

@@ -22,6 +22,31 @@ class AddrManImpl;
 /** Default for -checkaddrman */
 static constexpr int32_t DEFAULT_ADDRMAN_CONSISTENCY_CHECKS{0};
 
+/** Test-only struct, capturing info about an address in AddrMan */
+struct AddressPosition {
+    // Whether the address is in the new or tried table
+    const bool tried;
+
+    // Addresses in the tried table should always have a multiplicity of 1.
+    // Addresses in the new table can have multiplicity between 1 and
+    // ADDRMAN_NEW_BUCKETS_PER_ADDRESS
+    const int multiplicity;
+
+    // If the address is in the new table, the bucket and position are
+    // populated based on the first source who sent the address.
+    // In certain edge cases, this may not be where the address is currently
+    // located.
+    const int bucket;
+    const int position;
+
+    bool operator==(AddressPosition other) {
+        return std::tie(tried, multiplicity, bucket, position) ==
+               std::tie(other.tried, other.multiplicity, other.bucket, other.position);
+    }
+    explicit AddressPosition(bool tried_in, int multiplicity_in, int bucket_in, int position_in)
+        : tried{tried_in}, multiplicity{multiplicity_in}, bucket{bucket_in}, position{position_in} {}
+};
+
 /** Stochastic address manager
  *
  * Design goals:
@@ -142,6 +167,15 @@ public:
     void SetServices(const CService& addr, ServiceFlags nServices);
 
     const std::vector<bool>& GetAsmap() const;
+
+    /** Test-only function
+     * Find the address record in AddrMan and return information about its
+     * position.
+     * @param[in] addr       The address record to look up.
+     * @return               Information about the address record in AddrMan
+     *                       or nullopt if address is not found.
+     */
+    std::optional<AddressPosition> FindAddressEntry(const CAddress& addr);
 };
 
 #endif // BITCOIN_ADDRMAN_H