All Known Implementing Classes:
AbuseReason, AbuseSeverity, Certificate, DatabaseEntry, DataStructureImpl, DateAndFlags, DeliveryInstructions, Destination, EncryptedBuildRecord, EncryptedLeaseSet, GarlicClove, Hash, Hash384, Hash512, InfoHash, KeyCertificate, KeysAndCert, Lease, Lease2, LeaseSet, LeaseSet2, LocalHash, MetaLease, MetaLeaseSet, NextSessionKey, NID, NodeInfo, Payload, Peer, PrivateKey, PublicKey, RouterAddress, RouterIdentity, RouterInfo, RSASigningPrivateCrtKey, SendMessageOptions, SessionConfig, SessionKey, SessionKeyAndNonce, SHA1Hash, ShortEncryptedBuildRecord, Signature, SigningPrivateKey, SigningPublicKey, SimpleDataStructure, TokenKey, VerifiedDestination
public interface DataStructure
Base interface defining standard binary representation for I2P data structures.

DataStructure provides the foundation for all I2P protocol data:

  • Binary Protocol: Defines exact bit-level representation
  • Serialization: Standard methods for reading/writing to streams
  • Network Compatibility: Ensures consistent data encoding
  • Validation: Built-in integrity and format checking

Core Operations:

Integrity Protection:

  • Immutable After Initialization: Prevents modification after deserialization
  • IllegalStateException: Thrown when modification is attempted
  • NetDb Protection: Safeguards network database from corruption
  • Message Safety: Protects I2NP messages during transmission

Usage Throughout I2P:

  • I2NP Messages: All protocol messages implement DataStructure
  • NetDb Entries: RouterInfo and LeaseSet storage format
  • I2CP Protocol: Client-router communication data
  • Cryptography: Keys, signatures, and certificates
  • Routing: Tunnel IDs, leases, and routing information

Implementation Guidelines:

  • Do Not Reuse: Create new instances for each data element
  • Thread Safety: Protection is not guaranteed to be thread-safe
  • Corruption Prevention: Multiple protection layers but not foolproof
  • Direct Modification: Avoid modifying internal byte[] arrays

Security Considerations:

  • Input Validation: Always validate deserialized data
  • Bounds Checking: Prevent buffer overflows and underflows
  • Exception Handling: Properly handle DataFormatException
  • Memory Safety: Be cautious with direct byte array access

Performance Aspects:

  • Efficient Serialization: Optimized for network transmission
  • Minimal Overhead: Compact binary representation
  • Fast Validation: Quick integrity and format checking
  • Memory Management: Careful allocation and cleanup

Common Implementations:

  • Method Summary

    All Methods
    Modifier and Type
    Method
    Description
    Hash
    calculateHash()
    Calculate the SHA256 value of this object (useful for a few scenarios).
    void
    fromBase64(String data)
    Load the structure from the provided base64 string.
    void
    fromByteArray(byte[] data)
    Loads structure from the data provided
    void
    readBytes(InputStream in)
    Load up the current object with data from the given stream.
    String
    toBase64()
    Render the structure into modified base 64 notation.
    byte[]
    toByteArray()
    Convert the structure to a byte array.
    void
    writeBytes(OutputStream out)
    Write out the data structure to the stream, using the format defined in the I2P data structure specification.

  • Method Details

    • readBytes

      void readBytes(InputStream in) throws DataFormatException, IOException
      Load up the current object with data from the given stream. Data loaded this way must match the I2P data structure specification.

      Warning - many classes will throw IllegalStateException if data is already set.

      Parameters:
      in - stream to read from
      Throws:
      DataFormatException - if the data is improperly formatted
      IOException - if there was a problem reading the stream

    • writeBytes

      void writeBytes(OutputStream out) throws DataFormatException, IOException
      Write out the data structure to the stream, using the format defined in the I2P data structure specification.
      Parameters:
      out - stream to write to
      Throws:
      DataFormatException - if the data was incomplete or not yet ready to be written
      IOException - if there was a problem writing to the stream

    • toBase64

      String toBase64()
      Render the structure into modified base 64 notation.
      Returns:
      null on error

    • fromBase64

      void fromBase64(String data) throws DataFormatException
      Load the structure from the provided base64 string.

      Warning - many classes will throw IllegalStateException if data is already set. Warning - many classes will throw IllegalArgumentException if data is the wrong size.

      Parameters:
      data - base64 encoded string to load from
      Throws:
      DataFormatException - if the data format is invalid

    • toByteArray

      byte[] toByteArray()
      Convert the structure to a byte array.
      Returns:
      may be null if data is not set

    • fromByteArray

      void fromByteArray(byte[] data) throws DataFormatException
      Loads structure from the data provided

      Warning - many classes will throw IllegalStateException if data is already set. Warning - many classes will throw IllegalArgumentException if data is the wrong size.

      Parameters:
      data - byte array to load from
      Throws:
      DataFormatException - if the data format is invalid

    • calculateHash

      Hash calculateHash()
      Calculate the SHA256 value of this object (useful for a few scenarios).
      Returns:
      SHA256 hash, or null if there were problems (data format or io errors)