java.lang.Object
net.i2p.i2ptunnel.RequestValidator
public class RequestValidatorextends Object
Validates HTTP requests for security and policy compliance.

This class encapsulates all request validation logic for I2PTunnelHTTPServer, including hostname validation (detecting attempts to access localhost/loopback), inproxy rejection, referer validation, and user-agent filtering.

Validations are performed based on configuration options set in the tunnel's client options properties.

  • Field Details

    • _log

      private final Log _log
      Logger for this class.

    • _peerB32

      private final String _peerB32
      Base32 of the peer being checked.

    • _opts

      private final Properties _opts
      Tunnel options the request arrived on.

    • _blocklistManager

      private final BlocklistManager _blocklistManager
      Lists the peer may be blocked by.

  • Constructor Details

    • RequestValidator

      public RequestValidator(Log log, String peerB32, Properties opts, BlocklistManager blocklistManager)
      Creates a new RequestValidator.
      Parameters:
      log - the Log instance for logging validation events
      peerB32 - the Base32-encoded peer destination for logging
      opts - the tunnel client options for validation configuration
      blocklistManager - the BlocklistManager for logging blocked destinations; may be null

  • Method Details

    • validateHostname

      public RequestValidator.ValidationResult validateHostname(String hostname, StringBuilder command)
      Validates a hostname from an HTTP request.

      This method checks for several security issues:

      • Attempts to access localhost or loopback addresses
      • DNS blocking (0.0.0.0 or :: responses)
      • Non-I2P/non-onion hostnames that resolve to private addresses

      Valid hostnames ending in .i2p or .onion are passed through without validation, as these are expected I2P/eepSite or Tor addresses.

      Parameters:
      hostname - the Host header value from the request; may be null
      command - the full request command for blocklist checking
      Returns:
      a ValidationResult containing the validation outcome and any error response

    • shouldRejectInproxy

      public boolean shouldRejectInproxy(Map<String, List<String>> headers)
      Checks if the request should be rejected based on inproxy headers.

      When the OPT_REJECT_INPROXY option is enabled, requests containing X-Forwarded-For, X-Forwarded-Server, Forwarded, or X-Forwarded-Host headers are rejected to prevent proxy abuse.

      Parameters:
      headers - the HTTP request headers
      Returns:
      true if the request should be rejected, false otherwise

    • buildInproxyRejectLog

      public String buildInproxyRejectLog(Map<String, List<String>> headers)
      Builds a detailed log message for inproxy rejection.

      This method extracts all relevant headers for logging purposes when an inproxy request is rejected.

      Parameters:
      headers - the HTTP request headers
      Returns:
      a formatted string suitable for logging

    • shouldRejectReferer

      public boolean shouldRejectReferer(Map<String, List<String>> headers)
      Checks if the request should be rejected based on referer header.

      When the OPT_REJECT_REFERER option is enabled, requests with absolute URIs (starting with http:// or https://) in the Referer header are rejected to prevent information leakage.

      Parameters:
      headers - the HTTP request headers
      Returns:
      true if the request should be rejected, false otherwise

    • getRefererForLog

      public String getRefererForLog(Map<String, List<String>> headers)
      Extracts the referer URL for logging purposes.

      Strips the "Referer: " prefix from the header value.

      Parameters:
      headers - the HTTP request headers
      Returns:
      the referer URL without the header prefix, or null if not available

    • shouldRejectUserAgent

      public boolean shouldRejectUserAgent(Map<String, List<String>> headers)
      Checks if the request should be rejected based on user-agent header.

      When the OPT_REJECT_USER_AGENTS option is enabled, requests with blacklisted user agents are rejected. The blacklist is configured via the OPT_USER_AGENTS option as a comma-separated list.

      A special case is made for user agents starting with "MYOB" which are always allowed. Also, if the blacklist contains "none", requests without a User-Agent header are rejected.

      Parameters:
      headers - the HTTP request headers
      Returns:
      true if the request should be rejected, false otherwise

    • getUserAgentForCheck

      public String getUserAgentForCheck(Map<String, List<String>> headers)
      Extracts the user agent for blacklisting checks.
      Parameters:
      headers - the HTTP request headers
      Returns:
      the user agent string, or null if not present