net.i2p.i2ptunnel

Class RequestValidator

java.lang.Object

net.i2p.i2ptunnel.RequestValidator

public class RequestValidator
extends 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.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RequestValidator.ValidationResult Encapsulates the result of hostname validation.

Constructor Summary

Constructors

Constructor and Description
RequestValidator(Log log, String peerB32, Properties opts, BlocklistManager blocklistManager) Creates a new RequestValidator.

Method Summary

Modifier and Type	Method and Description
String	buildInproxyRejectLog(Map<String,List<String>> headers) Builds a detailed log message for inproxy rejection.
String	getRefererForLog(Map<String,List<String>> headers) Extracts the referer URL for logging purposes.
String	getUserAgentForCheck(Map<String,List<String>> headers) Extracts the user agent for blacklisting checks.
boolean	shouldRejectInproxy(Map<String,List<String>> headers) Checks if the request should be rejected based on inproxy headers.
boolean	shouldRejectReferer(Map<String,List<String>> headers) Checks if the request should be rejected based on referer header.
boolean	shouldRejectUserAgent(Map<String,List<String>> headers) Checks if the request should be rejected based on user-agent header.
RequestValidator.ValidationResult	validateHostname(String hostname, StringBuilder command) Validates a hostname from an HTTP request.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

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 Detail

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

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

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

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

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

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

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