aeron-io/aeron · error · IllegalArgumentException

Invalid address length

Error message

Invalid address length: ${address.length}

What it means

ResolutionEntryFlyweight.putAddress validates the address byte-array length against the resolution type before writing it into the flyweight. For RES_TYPE_NAME_TO_IP4_MD the address must be exactly ADDRESS_LENGTH_IP4 (4) bytes; any other length throws IllegalArgumentException. This guards against writing malformed addresses into name-to-IP4 resolution entries in the control protocol.

Solutions

1. Check address.length == 4 before calling putAddress for IP4 entries.
2. Ensure resType() matches the actual address family of the data.
3. For IPv6 data, set the entry type to RES_TYPE_NAME_TO_IP6_MD instead.
4. Validate the source of the address bytes (e.g. InetAddress.getAddress() length) before encoding.

Example fix

// before
flyweight.resType(RES_TYPE_NAME_TO_IP4_MD);
flyweight.putAddress(inet6Address.getAddress()); // 16 bytes into IP4 entry
// after
final byte[] bytes = address.getAddress();
flyweight.resType(bytes.length == 4 ? RES_TYPE_NAME_TO_IP4_MD : RES_TYPE_NAME_TO_IP6_MD);
flyweight.putAddress(bytes);

if (address != null && address.length == ResolutionEntryFlyweight.ADDRESS_LENGTH_IP4
    && flyweight.resType() == ResolutionEntryFlyweight.RES_TYPE_NAME_TO_IP4_MD)
{
    flyweight.putAddress(address);
}

boolean isIp4AddressBytes(final byte[] address)
{
    return address != null && address.length == 4;
}

try
{
    flyweight.putAddress(address);
}
catch (final IllegalArgumentException ex)
{
    LOGGER.error("resolution entry address length mismatch", ex);
}

When it happens

Trigger: Calling putAddress with an address array whose length is not 4 while resType() is RES_TYPE_NAME_TO_IP4_MD — e.g. passing an IPv6 address, a hostname byte array, or an empty array.

Common situations: Mixing IPv4 and IPv6 addresses when building resolution entries; parsing a name-resolution response and re-encoding with the wrong resType; test fixtures with placeholder addresses.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Insufficient length:
• Invalid fragmentCountLimit=" + fragmentCountLimit
• Invalid catalog capacity provided: expected value >= " +…
• recordingId " + recordingId + " is less than or equal to…
• className is empty

AI-assisted analysis of aeron-io/aeron@6d60124e15 (2026-09-12). Data as JSON: /api/errors/bcab13f1c133d3b6. Report an issue: GitHub.

Appendix: source

Thrown at aeron-client/src/main/java/io/aeron/protocol/ResolutionEntryFlyweight.java:246

    public int ageInMs()
    {
        return getInt(AGE_IN_MS_FIELD_OFFSET, LITTLE_ENDIAN);
    }

    /**
     * Put the address into the resolution entry. It must come after calling {@link #resType(byte)}.
     *
     * @param address to be written for the resolution entry.
     * @return this for a fluent API.
     */
    public ResolutionEntryFlyweight putAddress(final byte[] address)
    {
        switch (resType())
        {
            case RES_TYPE_NAME_TO_IP4_MD:
                if (ADDRESS_LENGTH_IP4 != address.length)
                {
                    throw new IllegalArgumentException("Invalid address length: " + address.length);
                }
                putBytes(ADDRESS_FIELD_OFFSET, address, 0, ADDRESS_LENGTH_IP4);
                break;

            case RES_TYPE_NAME_TO_IP6_MD:
                if (ADDRESS_LENGTH_IP6 != address.length)
                {
                    throw new IllegalArgumentException("Invalid address length: " + address.length);
                }
                putBytes(ADDRESS_FIELD_OFFSET, address, 0, ADDRESS_LENGTH_IP6);
                break;

            default:
                throw new IllegalStateException("unknown RES_TYPE=" + resType());
        }

        return this;
    }

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