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io.undertow.server.handlers.ForwardedHandler Maven / Gradle / Ivy
package io.undertow.server.handlers;
import io.undertow.UndertowLogger;
import io.undertow.server.HandlerWrapper;
import io.undertow.server.HttpHandler;
import io.undertow.server.HttpServerExchange;
import io.undertow.server.handlers.builder.HandlerBuilder;
import io.undertow.util.HeaderValues;
import io.undertow.util.Headers;
import io.undertow.util.NetworkUtils;
import java.net.InetSocketAddress;
import java.util.Collections;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import static io.undertow.UndertowMessages.MESSAGES;
/**
* Handler that implements rfc7239 Forwarded header
*
* @author Stuart Douglas
*/
public class ForwardedHandler implements HttpHandler {
public static final String BY = "by";
public static final String FOR = "for";
public static final String HOST = "host";
public static final String PROTO = "proto";
private static final String UNKNOWN = "unknown";
private final HttpHandler next;
public ForwardedHandler(HttpHandler next) {
this.next = next;
}
@Override
public void handleRequest(HttpServerExchange exchange) throws Exception {
HeaderValues forwarded = exchange.getRequestHeaders().get(Headers.FORWARDED);
if (forwarded != null) {
Map values = new HashMap<>();
for (String val : forwarded) {
parseHeader(val, values);
}
String host = values.get(Token.HOST);
String proto = values.get(Token.PROTO);
String by = values.get(Token.BY);
String forVal = values.get(Token.FOR);
if (host != null) {
exchange.getRequestHeaders().put(Headers.HOST, host);
exchange.setDestinationAddress(InetSocketAddress.createUnresolved(exchange.getHostName(), exchange.getHostPort()));
} else if (by != null) {
//we only use 'by' if the host is null
InetSocketAddress destAddress = parseAddress(by);
if (destAddress != null) {
exchange.setDestinationAddress(destAddress);
}
}
if (proto != null) {
exchange.setRequestScheme(proto);
}
if (forVal != null) {
InetSocketAddress sourceAddress = parseAddress(forVal);
if (sourceAddress != null) {
exchange.setSourceAddress(sourceAddress);
}
}
}
next.handleRequest(exchange);
}
static InetSocketAddress parseAddress(String address) {
try {
if (address.equals(UNKNOWN)) {
return null;
}
if (address.startsWith("_")) {
//obfnode, not much we can do with it
//if a client cares about it they will need to parse the header themselves
return null;
}
if (address.startsWith("[")) {
//ipv6 address
int index = address.indexOf("]");
String ipPart = address.substring(1, index);
int pos = address.indexOf(':', index);
if (pos == -1) {
return new InetSocketAddress(NetworkUtils.parseIpv6Address(ipPart), 0);
} else {
return new InetSocketAddress(NetworkUtils.parseIpv6Address(ipPart), parsePort(address.substring(pos + 1)));
}
} else {
int pos = address.indexOf(':');
if (pos == -1) {
return new InetSocketAddress(NetworkUtils.parseIpv4Address(address), 0);
} else {
return new InetSocketAddress(NetworkUtils.parseIpv4Address(address.substring(0, pos)), parsePort(address.substring(pos + 1)));
}
}
} catch (Exception e) {
UndertowLogger.REQUEST_IO_LOGGER.debug("Failed to parse address", e);
return null;
}
}
private static int parsePort(String substring) {
if (substring.startsWith("_")) {
return 0;
}
return Integer.parseInt(substring);
}
//package private for testing
static void parseHeader(final String header, Map response) {
if (response.size() == Token.values().length) {
//already parsed everything
return;
}
char[] headerChars = header.toCharArray();
SearchingFor searchingFor = SearchingFor.START_OF_NAME;
int nameStart = 0;
Token currentToken = null;
int valueStart = 0;
int escapeCount = 0;
boolean containsEscapes = false;
for (int i = 0; i < headerChars.length; i++) {
switch (searchingFor) {
case START_OF_NAME:
// Eliminate any white space before the name of the parameter.
if (headerChars[i] != ';' && !Character.isWhitespace(headerChars[i])) {
nameStart = i;
searchingFor = SearchingFor.EQUALS_SIGN;
}
break;
case EQUALS_SIGN:
if (headerChars[i] == '=') {
String paramName = String.valueOf(headerChars, nameStart, i - nameStart);
currentToken = TOKENS.get(paramName.toLowerCase(Locale.ENGLISH));
//we allow unkown tokens, but just ignore them
searchingFor = SearchingFor.START_OF_VALUE;
}
break;
case START_OF_VALUE:
if (!Character.isWhitespace(headerChars[i])) {
if (headerChars[i] == '"') {
valueStart = i + 1;
searchingFor = SearchingFor.LAST_QUOTE;
} else {
valueStart = i;
searchingFor = SearchingFor.END_OF_VALUE;
}
}
break;
case LAST_QUOTE:
if (headerChars[i] == '\\') {
escapeCount++;
containsEscapes = true;
} else if (headerChars[i] == '"' && (escapeCount % 2 == 0)) {
String value = String.valueOf(headerChars, valueStart, i - valueStart);
if (containsEscapes) {
StringBuilder sb = new StringBuilder();
boolean lastEscape = false;
for (int j = 0; j < value.length(); ++j) {
char c = value.charAt(j);
if (c == '\\' && !lastEscape) {
lastEscape = true;
} else {
lastEscape = false;
sb.append(c);
}
}
value = sb.toString();
containsEscapes = false;
}
if (currentToken != null && !response.containsKey(currentToken)) {
response.put(currentToken, value);
}
searchingFor = SearchingFor.START_OF_NAME;
escapeCount = 0;
} else {
escapeCount = 0;
}
break;
case END_OF_VALUE:
if (headerChars[i] == ';' || headerChars[i] == ',' || Character.isWhitespace(headerChars[i])) {
String value = String.valueOf(headerChars, valueStart, i - valueStart);
if (currentToken != null && !response.containsKey(currentToken)) {
response.put(currentToken, value);
}
searchingFor = SearchingFor.START_OF_NAME;
}
break;
}
}
if (searchingFor == SearchingFor.END_OF_VALUE) {
// Special case where we reached the end of the array containing the header values.
String value = String.valueOf(headerChars, valueStart, headerChars.length - valueStart);
if (currentToken != null && !response.containsKey(currentToken)) {
response.put(currentToken, value);
}
} else if (searchingFor != SearchingFor.START_OF_NAME) {
// Somehow we are still in the middle of searching for a current value.
throw MESSAGES.invalidHeader();
}
}
enum Token {
BY,
FOR,
HOST,
PROTO
}
private static final Map TOKENS;
static {
Map map = new HashMap<>();
for (Token token : Token.values()) {
map.put(token.name().toLowerCase(), token);
}
TOKENS = Collections.unmodifiableMap(map);
}
private enum SearchingFor {
START_OF_NAME, EQUALS_SIGN, START_OF_VALUE, LAST_QUOTE, END_OF_VALUE;
}
public static final HandlerWrapper WRAPPER = new HandlerWrapper() {
@Override
public HttpHandler wrap(HttpHandler handler) {
return new ForwardedHandler(handler);
}
};
public static class Builder implements HandlerBuilder {
@Override
public String name() {
return "forwarded";
}
@Override
public Map> parameters() {
return Collections.emptyMap();
}
@Override
public Set requiredParameters() {
return Collections.emptySet();
}
@Override
public String defaultParameter() {
return null;
}
@Override
public HandlerWrapper build(Map config) {
return WRAPPER;
}
}
}
