compareAddresses() — netty Function Reference

Architecture documentation for the compareAddresses() function in MacAddressUtil.java from the netty codebase.

Function java CommonUtil Internal calls 1 called by 1

Entity Profile

CommonUtil→ Internal→ compareAddresses() — netty Function Reference

Dependency Diagram

graph TD
  bce5fa35_f827_f8d9_1f74_97f9adbfbbef["compareAddresses()"]
  a4685b43_b51c_914d_456a_1efa65aff7a6["MacAddressUtil"]
  bce5fa35_f827_f8d9_1f74_97f9adbfbbef -->|defined in| a4685b43_b51c_914d_456a_1efa65aff7a6
  076ea31f_ecd7_dd77_e9b3_a6aaa2aded58["bestAvailableMac()"]
  076ea31f_ecd7_dd77_e9b3_a6aaa2aded58 -->|calls| bce5fa35_f827_f8d9_1f74_97f9adbfbbef
  9305d4fa_a1fb_1272_769e_bfae8c4ad4c4["scoreAddress()"]
  bce5fa35_f827_f8d9_1f74_97f9adbfbbef -->|calls| 9305d4fa_a1fb_1272_769e_bfae8c4ad4c4
  style bce5fa35_f827_f8d9_1f74_97f9adbfbbef fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

common/src/main/java/io/netty/util/internal/MacAddressUtil.java lines 202–243

    static int compareAddresses(byte[] current, byte[] candidate) {
        if (candidate == null || candidate.length < EUI48_MAC_ADDRESS_LENGTH) {
            return 1;
        }

        // Must not be filled with only 0 and 1.
        boolean onlyZeroAndOne = true;
        for (byte b: candidate) {
            if (b != 0 && b != 1) {
                onlyZeroAndOne = false;
                break;
            }
        }

        if (onlyZeroAndOne) {
            return 1;
        }

        // Must not be a multicast address
        if ((candidate[0] & 1) != 0) {
            return 1;
        }

        // Prefer globally unique address.
        if ((candidate[0] & 2) == 0) {
            if (current.length != 0 && (current[0] & 2) == 0) {
                // Both current and candidate are globally unique addresses.
                return 0;
            } else {
                // Only candidate is globally unique.
                return -1;
            }
        } else {
            if (current.length != 0 && (current[0] & 2) == 0) {
                // Only current is globally unique.
                return 1;
            } else {
                // Both current and candidate are non-unique.
                return 0;
            }
        }
    }