How to add a custom header in Spring WebFilter? - spring

Question

I'm trying to add a custom filter before I invoke my REST Service. In this below class, I'm trying to add the custom filter in the HttpRequest but I'm getting error :-
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.computeIfAbsent(Collections.java:1535) ~[na:1.8.0_171]
at org.springframework.util.CollectionUtils$MultiValueMapAdapter.add(CollectionUtils.java:459) ~[spring-core-5.0.7.RELEASE.jar:5.0.7.RELEASE]
public class AuthenticationWebFilter implements WebFilter {
private static final Logger LOGGER = LoggerFactory.getLogger(AuthenticationWebFilter.class);
#Autowired
private TokenServiceRequest tokenServiceRequest;
#Autowired
private AuthenticationProvider authenticationProvider;
public AuthenticationWebFilter(TokenServiceRequest tokenServiceRequest, AuthenticationProvider authenticationProvider) {
super();
this.tokenServiceRequest = tokenServiceRequest;
this.authenticationProvider = authenticationProvider;
}
#Override
public Mono<Void> filter(ServerWebExchange serverWebExchange, WebFilterChain webFilterChain) {
HttpHeaders requestHeaders = serverWebExchange.getRequest().getHeaders();
HttpHeaders responseHeaders = serverWebExchange.getResponse().getHeaders();
LOGGER.info("Response HEADERS: "+responseHeaders);
LOGGER.info("Request HEADERS: "+serverWebExchange.getRequest().getHeaders());
tokenServiceRequest.setUsername(serverWebExchange.getRequest().getHeaders().getFirst(CommerceConnectorConstants.USERNAME));
tokenServiceRequest.setPassword(serverWebExchange.getRequest().getHeaders().getFirst(CommerceConnectorConstants.PASSWORD));
tokenServiceRequest.setClientId(serverWebExchange.getRequest().getHeaders().getFirst(CommerceConnectorConstants.CLIENT_ID));
tokenServiceRequest.setSecretClient(serverWebExchange.getRequest().getHeaders().getFirst(CommerceConnectorConstants.SECRET_CLIENT));
LOGGER.info("Token Received: " + authenticationProvider.getUserAccessToken(tokenServiceRequest).getTokenId());
//responseHeaders.set(CommerceConnectorConstants.X_AUTH_TOKEN, authenticationProvider.getUserAccessToken(tokenServiceRequest).getTokenId());
//responseHeaders.add(CommerceConnectorConstants.X_AUTH_TOKEN, authenticationProvider.getUserAccessToken(tokenServiceRequest).getTokenId());
//This below code is not working
serverWebExchange.getRequest().getQueryParams().add("test", "value");
//This below code is not working
//serverWebExchange.getRequest().getHeaders().add(CommerceConnectorConstants.X_AUTH_TOKEN, authenticationProvider.getUserAccessToken(tokenServiceRequest).getTokenId());
LOGGER.info("Exiting filter#AuthenticationWebFilter");
return webFilterChain.filter(serverWebExchange);
}
}
In HTTPResponse, I can set the custom headers but my requirement is to add the custom header in the HTTPRequest. Please advise.

Answer 1

If you're in spring cloud gateway, request header could be modified by implements GlobalFilter or GatewayFilter.
#Component
public class LogFilter implements GlobalFilter, Ordered {
private Logger LOG = LoggerFactory.getLogger(LogFilter.class);
#Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
return chain.filter(
exchange.mutate().request(
exchange.getRequest().mutate()
.header("customer-header", "customer-header-value")
.build())
.build());
}
#Override
public int getOrder() {
return 0;
} }
If you're in ZuulFilter, addZuulRequestHeader could modified the request header.
RequestContext.getCurrentContext().addZuulRequestHeader("customer-header", "customer-header-value");
Hope it's helpful.

Answer 2

public class CustomTokenFilter implements WebFilter {
#Override
public Mono<Void> filter(ServerWebExchange serverWebExchange, WebFilterChain webFilterChain) {
ServerHttpRequest mutateRequest = serverWebExchange.getRequest().mutate()
.header("token", "test")
.build();
ServerWebExchange mutateServerWebExchange = serverWebExchange.mutate().request(mutateRequest).build();
return webFilterChain.filter(mutateServerWebExchange);
}
}

Answer 3

I think the exception is thrown because of security reasons. It would be nasty if a filter could add/modify the HTTP request headers. Of course, you can accomplish this by creating a series of decorators:
import org.springframework.http.HttpHeaders;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.util.MultiValueMap;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.ServerWebExchangeDecorator;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;
public class CustomFilter implements WebFilter {
public Mono<Void> filter(ServerWebExchange serverWebExchange, WebFilterChain webFilterChain) {
ServerWebExchangeDecorator decorator = new ServerWebExchangeDecoratorImpl(serverWebExchange);
//do your stuff using decorator
return webFilterChain.filter(decorator);
}
}
class ServerWebExchangeDecoratorImpl extends ServerWebExchangeDecorator {
private ServerHttpRequestDecorator requestDecorator;
public ServerWebExchangeDecoratorImpl(ServerWebExchange delegate) {
super(delegate);
this.requestDecorator = new ServerHttpRequestDecoratorImpl(delegate.getRequest());
}
#Override
public ServerHttpRequest getRequest() {
return requestDecorator;
}
}
class ServerHttpRequestDecoratorImpl extends ServerHttpRequestDecorator {
// your own query params implementation
private MultiValueMap queryParams;
public ServerHttpRequestDecoratorImpl(ServerHttpRequest request) {
super(request);
this.queryParams = new HttpHeaders();
this.queryParams.addAll(request.getQueryParams());
}
#Override
public MultiValueMap<String, String> getQueryParams() {
return queryParams;
}
//override other methods if you want to modify the behavior
}

Answer 4

I'm having the same problem because headers already have the same key; My solution is to set the key in the header, first check whether the key exists;
#Configuration
public class AuthGatewayFilter implements GlobalFilter, Ordered {
#Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
Consumer<HttpHeaders> httpHeaders = httpHeader -> {
// check exists
if(StringUtils.isBlank(httpHeader.getFirst("xxx"))){
httpHeader.add("xxx", "xxx");
}
};
ServerHttpRequest serverHttpRequest = exchange.getRequest().mutate().headers(httpHeaders).build();
exchange = exchange.mutate().request(serverHttpRequest).build();
return chain.filter(exchange);
}
}