springboot 1.x 2.x tomcat支持特殊字符，URL中有{}[]等报400

springboot 1.x 2.x tomcat支持特殊字符

现象

正常访问一个get请求，页面返回400：

后台日志报错：

2018-08-09 21:39:28.915  INFO 6750 --- [nio-8080-exec-1] o.apache.coyote.http11.Http11Processor   : Error parsing HTTP request header
 Note: further occurrences of HTTP header parsing errors will be logged at DEBUG level.

java.lang.IllegalArgumentException: Invalid character found in the request target. The valid characters are defined in RFC 7230 and RFC 3986
    at org.apache.coyote.http11.Http11InputBuffer.parseRequestLine(Http11InputBuffer.java:479) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:684) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:800) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1471) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_111]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_111]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.32.jar:8.5.32]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_111]

稍微百度一下就可以知道这是URL中有特殊字符，新版本的Tomcat严格按照RFC 3986规范进行访问解析，而 RFC 3986规范规定Url中只允许包含英文字母（a-zA-Z）、数字（0-9）、-_.~4个特殊字符以及所有保留字符(RFC3986/7320中指定了以下字符为保留字符：! * ’ ( ) ; : @ & = + $ , / ? # [ ]) 。

RFC7230

3.2.6. Field Value Components
Most HTTP header field values are defined using common syntax
components (token, quoted-string, and comment) separated by
whitespace or specific delimiting characters. Delimiters are chosen
from the set of US-ASCII visual characters not allowed in a token
(DQUOTE and “(),/:;<=>?@[]{}”).

所以这个问题特别容易出现在升级spring boot版本的时候，spring boot内嵌的tomcat也会升级，老版的tomcat运行正常，新版的tomcat就会出错。而深究特殊字符来源，一般是get请求中包含json字符串、搜索特殊字符关键字等。

解决方案

如果是在开发新业务过程中出现这个问题，可以选择新的方案，避免在GET请求中使用! * ’ ( ) ; : @ & = + $ , / ? # [ ])等字符，毕竟符合规范是最好的出路。

如果是升级，可以使用下面的方式来解决：

sprintboot 1.x(1.5.21测试有效)

import org.springframework.boot.context.embedded.ConfigurableEmbeddedServletContainer;
import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizer;
import org.springframework.boot.context.embedded.tomcat.TomcatConnectorCustomizer;
import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * Create by IntelliJ IDEA
 *
 * @author chenlei
 * @dateTime 2019/5/23 18:09
 * @description TomcatConfig
 */
@Configuration
public class TomcatConfig {

    @Bean
    public EmbeddedServletContainerCustomizer containerCustomizer() {
        return new MyCustomizer();
    }

    private static class MyCustomizer implements EmbeddedServletContainerCustomizer {

        @Override
        public void customize(ConfigurableEmbeddedServletContainer factory) {
            if (factory instanceof TomcatEmbeddedServletContainerFactory) {
                customizeTomcat((TomcatEmbeddedServletContainerFactory) factory);
            }
        }

        void customizeTomcat(TomcatEmbeddedServletContainerFactory factory) {
            factory.addConnectorCustomizers((TomcatConnectorCustomizer) connector -> {
                connector.setAttribute("relaxedPathChars", "<>[\\]^`{|}");
                connector.setAttribute("relaxedQueryChars", "<>[\\]^`{|}");
            });
        }

    }
}

springboot 2.x(2.1.3测试有效)

import org.springframework.boot.web.embedded.tomcat.TomcatConnectorCustomizer;
import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * Create by IntelliJ IDEA
 *
 * @author chenlei
 * @dateTime 2019/5/23 18:09
 * @description TomcatConfig
 */
@Configuration
public class TomcatConfig {

    @Bean
    public ServletWebServerFactory webServerFactory() {
        TomcatServletWebServerFactory fa = new TomcatServletWebServerFactory();
        fa.addConnectorCustomizers((TomcatConnectorCustomizer) connector -> connector.setProperty("relaxedQueryChars", "[]{}"));
        return fa;
    }

}

总结

这次问题出现的原因是升级springboot导致的，因为之前使用的较低版本的springboot(1.5.10.RELEASE)，升级到1.5.21.RELEASE后出现了该问题。因为之前在springboot 2.x上遇到过这个问题，因此知道问题所在，但springboot 1.x和2.x的解决方案有一点差异，这里记录一下。

后续

后面再做了一次Tomcat升级，从9.0.21升级到9.0.31，突然又出现这个问题，问题原因是一样的，tomcat对非法字符的控制更加严格了，严格遵循最新的RFC7230，我们除了把所有的非法字符全部加到relaxedQueryChars以外，还添加了另一项配置rejectIllegalHeader：

@Configuration
public class TomcatConfig {

    @Bean
    public ServletWebServerFactory webServerFactory() {
        TomcatServletWebServerFactory fa = new TomcatServletWebServerFactory();
        fa.addConnectorCustomizers(connector -> {
            connector.setProperty("relaxedQueryChars", "(),/:;<=>?@[\\]{}");
            connector.setProperty("rejectIllegalHeader", "false");
        });
        return fa;
    }
}

关于这个配置的解释参考：tomcat-9.0-doc

rejectIllegalHeader

If an HTTP request is received that contains an illegal header name or value (e.g. the header name is not a token) this setting determines if the request will be rejected with a 400 response (true) or if the illegal header be ignored (false). The default value is true which will cause the request to be rejected.

这样配置后（1.x的配置类似），大部分URI和Header都可以兼容，但是正如文档里所说的，rejectIllegalHeader会导致非法的header忽略，即header信息将不会被服务器接收。

所以一旦Header里面有非法字符，对应的Header项将被忽略，服务器不会报400，但会跳过这个header项，比如升级过程中我们发现有API在header里传输中文，导致服务启报错，加了rejectIllegalHeader=false后，不报400，但程序找不到对应的Header，最后不得不删除这些不规范的header。