spring boot 使用过滤器过滤非法字符
有时候我们要配置我们自己的定义非法字符过滤,但 HttpServletRequest 对象是不可以改变的,那我们只好定义一个类,成为它的子类,重写它的方法,这样在Servelt中使用它方法时候,
就会进入我们重写方法,从而实现过滤
1、创建一个HTML过滤类,我过滤的是 html 和 xss,当然你们自己定义你们的过滤规则
package io.xiongdi.common.xss; import java.util.*; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ConcurrentMap; import java.util.logging.Logger; import java.util.regex.Matcher; import java.util.regex.Pattern; /** * @author wujiaxing * @date 2019-07-09 */ public final class HTMLFilter { /** * regex flag union representing /si modifiers in php **/ private static final int REGEX_FLAGS_SI = Pattern.CASE_INSENSITIVE | Pattern.DOTALL; private static final Pattern P_COMMENTS = Pattern.compile("<!--(.*?)-->", Pattern.DOTALL); private static final Pattern P_COMMENT = Pattern.compile("^!--(.*)--$", REGEX_FLAGS_SI); private static final Pattern P_TAGS = Pattern.compile("<(.*?)>", Pattern.DOTALL); private static final Pattern P_END_TAG = Pattern.compile("^/([a-z0-9]+)", REGEX_FLAGS_SI); private static final Pattern P_START_TAG = Pattern.compile("^([a-z0-9]+)(.*?)(/?)$", REGEX_FLAGS_SI); private static final Pattern P_QUOTED_ATTRIBUTES = Pattern.compile("([a-z0-9]+)=([\"'])(.*?)\\2", REGEX_FLAGS_SI); private static final Pattern P_UNQUOTED_ATTRIBUTES = Pattern.compile("([a-z0-9]+)(=)([^\"\\s']+)", REGEX_FLAGS_SI); private static final Pattern P_PROTOCOL = Pattern.compile("^([^:]+):", REGEX_FLAGS_SI); private static final Pattern P_ENTITY = Pattern.compile("&#(\\d+);?"); private static final Pattern P_ENTITY_UNICODE = Pattern.compile("&#x([0-9a-f]+);?"); private static final Pattern P_ENCODE = Pattern.compile("%([0-9a-f]{2});?"); private static final Pattern P_VALID_ENTITIES = Pattern.compile("&([^&;]*)(?=(;|&|$))"); private static final Pattern P_VALID_QUOTES = Pattern.compile("(>|^)([^<]+?)(<|$)", Pattern.DOTALL); private static final Pattern P_END_ARROW = Pattern.compile("^>"); private static final Pattern P_BODY_TO_END = Pattern.compile("<([^>]*?)(?=<|$)"); private static final Pattern P_XML_CONTENT = Pattern.compile("(^|>)([^<]*?)(?=>)"); private static final Pattern P_STRAY_LEFT_ARROW = Pattern.compile("<([^>]*?)(?=<|$)"); private static final Pattern P_STRAY_RIGHT_ARROW = Pattern.compile("(^|>)([^<]*?)(?=>)"); private static final Pattern P_AMP = Pattern.compile("&"); private static final Pattern P_QUOTE = Pattern.compile("<"); private static final Pattern P_LEFT_ARROW = Pattern.compile("<"); private static final Pattern P_RIGHT_ARROW = Pattern.compile(">"); private static final Pattern P_BOTH_ARROWS = Pattern.compile("<>"); private static final ConcurrentMap<String, Pattern> P_REMOVE_PAIR_BLANKS = new ConcurrentHashMap<String, Pattern>(); private static final ConcurrentMap<String, Pattern> P_REMOVE_SELF_BLANKS = new ConcurrentHashMap<String, Pattern>(); /** * 一组允许的html元素,以及元素允许的属性 */ private final Map<String, List<String>> vAllowed; /** * 每个(允许的)html元素的打开标记数 */ private final Map<String, Integer> vTagCounts = new HashMap<String, Integer>(); /** * 必须总是自关闭的html元素(例如。“< img / > */ private final String[] vSelfClosingTags; /** * 必须始终具有独立的开始和结束标记的html元素(例如。“< b > < / b >”) */ private final String[] vNeedClosingTags; /** * 一组不允许的html元素 */ private final String[] vDisallowed; /** * 属性,应检查这些属性是否为有效协议 */ private final String[] vProtocolAtts; /** * 允许协议 */ private final String[] vAllowedProtocols; /** * 如果标签不包含任何内容(例如"<b></b>"或"<b />") */ private final String[] vRemoveBlanks; /** * html标记中允许的实体 */ private final String[] vAllowedEntities; /** * 标志,确定输入字符串中是否允许注释。 */ private final boolean stripComment; /** * 编码引用 */ private final boolean encodeQuotes; private boolean vDebug = false; /** * 标记决定是否尝试在呈现“不平衡的”标记时制作标记 * 尖括号(如。“<b text </b>”变为“<b> text </b>”)。 * 如果设为false,不平衡的尖括号将被html转义。 */ private final boolean alwaysMakeTags; public HTMLFilter() { this.vAllowed = new HashMap<>(); final ArrayList<String> aAtts = new ArrayList<>(); aAtts.add("href"); aAtts.add("target"); vAllowed.put("a", aAtts); final ArrayList<String> imgAtts = new ArrayList<>(); imgAtts.add("src"); imgAtts.add("width"); imgAtts.add("height"); imgAtts.add("alt"); vAllowed.put("img", imgAtts); final ArrayList<String> noAtts = new ArrayList<>(); vAllowed.put("b", noAtts); vAllowed.put("strong", noAtts); vAllowed.put("i", noAtts); vAllowed.put("em", noAtts); this.vSelfClosingTags = new String[]{"img"}; this.vNeedClosingTags = new String[]{"a", "b", "strong", "i", "em"}; this.vDisallowed = new String[]{}; this.vProtocolAtts = new String[]{"src", "href"}; this.vAllowedProtocols = new String[]{"http", "mailto", "https"}; this.vRemoveBlanks = new String[]{"a", "b", "strong", "i", "em"}; this.vAllowedEntities = new String[]{"amp", "lt", "gt", "quot"}; this.stripComment = true; this.encodeQuotes = true; this.alwaysMakeTags = true; } public HTMLFilter(boolean vDebug) { this(); this.vDebug = vDebug; } /** * 带map参数的构造函数 * assert 后面跟个冒号表达式。如果冒号前为 true,则冒号后面的被忽略。 * 如果冒号前为false,则抛出AssertionError ,错误信息内容为冒号后面的内容 * * @param conf 包含配置的conf映射。键匹配字段名 */ public HTMLFilter(final Map<String, Object> conf) { assert conf.containsKey("vAllowed") : "configuration requires vAllowed"; assert conf.containsKey("vSelfClosingTags") : "configuration requires vSelfClosingTags"; assert conf.containsKey("vNeedClosingTags") : "configuration requires vNeedClosingTags"; assert conf.containsKey("vDisallowed") : "configuration requires vDisallowed"; assert conf.containsKey("vAllowedProtocols") : "configuration requires vAllowedProtocols"; assert conf.containsKey("vProtocolAtts") : "configuration requires vProtocolAtts"; assert conf.containsKey("vRemoveBlanks") : "configuration requires vRemoveBlanks"; assert conf.containsKey("vAllowedEntities") : "configuration requires vAllowedEntities"; vAllowed = Collections.unmodifiableMap((Map<String, List<String>>) conf.get("vAllowed")); vSelfClosingTags = (String[]) conf.get("vSelfClosingTags"); vNeedClosingTags = (String[]) conf.get("vNeedClosingTags"); vDisallowed = (String[]) conf.get("vDisallowed"); vAllowedProtocols = (String[]) conf.get("vAllowedProtocols"); vProtocolAtts = (String[]) conf.get("vProtocolAtts"); vRemoveBlanks = (String[]) conf.get("vRemoveBlanks"); vAllowedEntities = (String[]) conf.get("vAllowedEntities"); stripComment = conf.containsKey("stripComment") ? (Boolean) conf.get("stripComment") : true; encodeQuotes = conf.containsKey("encodeQuotes") ? (Boolean) conf.get("encodeQuotes") : true; alwaysMakeTags = conf.containsKey("alwaysMakeTags") ? (Boolean) conf.get("alwaysMakeTags") : true; } private void reset() { vTagCounts.clear(); } private void debug(final String msg) { if (vDebug) { Logger.getAnonymousLogger().info(msg); } } /** * 我的一些PHP库函数版本 * * @param decimal * @return */ public static String chr(final int decimal) { return String.valueOf((char) decimal); } /** * html 的一些特殊字符进行替换,例如 > 就替换成 > * * @param s * @return */ public static String htmlSpecialChars(final String s) { String result = s; result = regexReplace(P_AMP, "&", result); result = regexReplace(P_QUOTE, """, result); result = regexReplace(P_LEFT_ARROW, "<", result); result = regexReplace(P_RIGHT_ARROW, ">", result); return result; } private static String regexReplace(final Pattern regex_pattern, final String replacement, final String s) { Matcher m = regex_pattern.matcher(s); return m.replaceAll(replacement); } public String filter(final String input) { reset(); String s = input; debug("************************************************"); debug(" INPUT: " + input); s = escapeComments(s); debug(" escapeComments: " + s); s = balanceHTML(s); debug(" balanceHTML: " + s); s = checkTags(s); debug(" checkTags: " + s); s = processRemoveBlanks(s); debug("processRemoveBlanks: " + s); s = validateEntities(s); debug(" validateEntites: " + s); debug("************************************************\n\n"); return s; } public boolean isAlwaysMakeTags() { return alwaysMakeTags; } public boolean isStripComments() { return stripComment; } private String escapeComments(final String s) { final Matcher m = P_COMMENTS.matcher(s); final StringBuffer buf = new StringBuffer(); if (m.find()) { //(.*?) final String match = m.group(1); m.appendReplacement(buf, Matcher.quoteReplacement("<!--" + htmlSpecialChars(match) + "-->")); } m.appendTail(buf); return buf.toString(); } private String balanceHTML(String s) { if (alwaysMakeTags) { // // try and form html // s = regexReplace(P_END_ARROW, "", s); s = regexReplace(P_BODY_TO_END, "<$1>", s); s = regexReplace(P_XML_CONTENT, "$1<$2", s); } else { // // escape stray brackets // s = regexReplace(P_STRAY_LEFT_ARROW, "<$1", s); s = regexReplace(P_STRAY_RIGHT_ARROW, "$1$2><", s); // // the last regexp causes '<>' entities to appear // (we need to do a lookahead assertion so that the last bracket can // be used in the next pass of the regexp) // s = regexReplace(P_BOTH_ARROWS, "", s); } return s; } private String checkTags(String s) { Matcher m = P_TAGS.matcher(s); final StringBuffer buf = new StringBuffer(); while (m.find()) { String replaceStr = m.group(1); replaceStr = processTag(replaceStr); m.appendReplacement(buf, Matcher.quoteReplacement(replaceStr)); } m.appendTail(buf); s = buf.toString(); // these get tallied in processTag // (remember to reset before subsequent calls to filter method) for (String key : vTagCounts.keySet()) { for (int ii = 0; ii < vTagCounts.get(key); ii++) { s += "</" + key + ">"; } } return s; } private String processRemoveBlanks(final String s) { String result = s; for (String tag : vRemoveBlanks) { if (!P_REMOVE_PAIR_BLANKS.containsKey(tag)) { P_REMOVE_PAIR_BLANKS.putIfAbsent(tag, Pattern.compile("<" + tag + "(\\s[^>]*)?></" + tag + ">")); } result = regexReplace(P_REMOVE_PAIR_BLANKS.get(tag), "", result); if (!P_REMOVE_SELF_BLANKS.containsKey(tag)) { P_REMOVE_SELF_BLANKS.putIfAbsent(tag, Pattern.compile("<" + tag + "(\\s[^>]*)?/>")); } result = regexReplace(P_REMOVE_SELF_BLANKS.get(tag), "", result); } return result; } private String processTag(final String s) { // ending tags Matcher m = P_END_TAG.matcher(s); if (m.find()) { final String name = m.group(1).toLowerCase(); if (allowed(name)) { if (!inArray(name, vSelfClosingTags)) { if (vTagCounts.containsKey(name)) { vTagCounts.put(name, vTagCounts.get(name) - 1); return "</" + name + ">"; } } } } // starting tags m = P_START_TAG.matcher(s); if (m.find()) { final String name = m.group(1).toLowerCase(); final String body = m.group(2); String ending = m.group(3); //debug( "in a starting tag, name='" + name + "'; body='" + body + "'; ending='" + ending + "'" ); if (allowed(name)) { String params = ""; final Matcher m2 = P_QUOTED_ATTRIBUTES.matcher(body); final Matcher m3 = P_UNQUOTED_ATTRIBUTES.matcher(body); final List<String> paramNames = new ArrayList<String>(); final List<String> paramValues = new ArrayList<String>(); while (m2.find()) { //([a-z0-9]+) paramNames.add(m2.group(1)); //(.*?) paramValues.add(m2.group(3)); } while (m3.find()) { //([a-z0-9]+) paramNames.add(m3.group(1)); //([^\"\\s']+) paramValues.add(m3.group(3)); } String paramName, paramValue; for (int ii = 0; ii < paramNames.size(); ii++) { paramName = paramNames.get(ii).toLowerCase(); paramValue = paramValues.get(ii); if (allowedAttribute(name, paramName)) { if (inArray(paramName, vProtocolAtts)) { paramValue = processParamProtocol(paramValue); } params += " " + paramName + "=\"" + paramValue + "\""; } } if (inArray(name, vSelfClosingTags)) { ending = " /"; } if (inArray(name, vNeedClosingTags)) { ending = ""; } if (ending == null || ending.length() < 1) { if (vTagCounts.containsKey(name)) { vTagCounts.put(name, vTagCounts.get(name) + 1); } else { vTagCounts.put(name, 1); } } else { ending = " /"; } return "<" + name + params + ending + ">"; } else { return ""; } } // comments m = P_COMMENT.matcher(s); if (!stripComment && m.find()) { return "<" + m.group() + ">"; } return ""; } private String processParamProtocol(String s) { s = decodeEntities(s); final Matcher m = P_PROTOCOL.matcher(s); if (m.find()) { final String protocol = m.group(1); if (!inArray(protocol, vAllowedProtocols)) { // bad protocol, turn into local anchor link instead s = "#" + s.substring(protocol.length() + 1, s.length()); if (s.startsWith("#//")) { s = "#" + s.substring(3, s.length()); } } } return s; } private String decodeEntities(String s) { StringBuffer buf = new StringBuffer(); Matcher m = P_ENTITY.matcher(s); while (m.find()) { final String match = m.group(1); final int decimal = Integer.decode(match).intValue(); m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal))); } m.appendTail(buf); s = buf.toString(); buf = new StringBuffer(); m = P_ENTITY_UNICODE.matcher(s); while (m.find()) { final String match = m.group(1); final int decimal = Integer.valueOf(match, 16).intValue(); m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal))); } m.appendTail(buf); s = buf.toString(); buf = new StringBuffer(); m = P_ENCODE.matcher(s); while (m.find()) { final String match = m.group(1); final int decimal = Integer.valueOf(match, 16).intValue(); m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal))); } m.appendTail(buf); s = buf.toString(); s = validateEntities(s); return s; } private String validateEntities(final String s) { StringBuffer buf = new StringBuffer(); // validate entities throughout the string Matcher m = P_VALID_ENTITIES.matcher(s); while (m.find()) { // ([^&;]*) final String one = m.group(1); // (?=(;|&|$)) final String two = m.group(2); m.appendReplacement(buf, Matcher.quoteReplacement(checkEntity(one, two))); } m.appendTail(buf); return encodeQuotes(buf.toString()); } private String encodeQuotes(final String s) { if (encodeQuotes) { StringBuffer buf = new StringBuffer(); Matcher m = P_VALID_QUOTES.matcher(s); while (m.find()) { // (>|^) final String one = m.group(1); // ([^<]+?) final String two = m.group(2); // (<|$) final String three = m.group(3); m.appendReplacement(buf, Matcher.quoteReplacement(one + regexReplace(P_QUOTE, """, two) + three)); } m.appendTail(buf); return buf.toString(); } else { return s; } } private String checkEntity(final String preamble, final String term) { return ";".equals(term) && isValidEntity(preamble) ? '&' + preamble : "&" + preamble; } private boolean isValidEntity(final String entity) { return inArray(entity, vAllowedEntities); } private static boolean inArray(final String s, final String[] array) { for (String item : array) { if (item != null && item.equals(s)) { return true; } } return false; } private boolean allowed(final String name) { return (vAllowed.isEmpty() || vAllowed.containsKey(name)) && !inArray(name, vDisallowed); } private boolean allowedAttribute(final String name, final String paramName) { return allowed(name) && (vAllowed.isEmpty() || vAllowed.get(name).contains(paramName)); } }
2、创建一个 xss 过滤类,继承HttpServletRequestWrapper,这个类是一个包装类
package io.xiongdi.common.xss; import com.google.common.net.HttpHeaders; import org.apache.commons.io.IOUtils; import org.apache.commons.lang.StringUtils; import org.springframework.http.MediaType; import javax.servlet.ReadListener; import javax.servlet.ServletInputStream; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import java.io.ByteArrayInputStream; import java.io.IOException; import java.util.LinkedHashMap; import java.util.Map; /** * xss 过滤处理 * 实现了HttpServletRequestWrapper的类,就可以成为HttpRequestWrapper的装饰类 * @author wujiaxing * @date 2019-07-10 */ public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper { /** * 没有包装过的 HttpServletRequest ,(特殊场景,需要自己过滤) */ private HttpServletRequest orgRequest; /** * html 过滤 */ private final static HTMLFilter htmlFilter = new HTMLFilter(); @Override public Map<String, String[]> getParameterMap() { Map<String, String[]> parameterMap = super.getParameterMap(); if (parameterMap.size() > 0) { Map<String, String[]> map = new LinkedHashMap<>(); for (String k : parameterMap.keySet()) { String[] v = parameterMap.get("s"); for (int i = 0; i < v.length; i++) { v[i] = xssEncode(v[i]); } map.put(xssEncode(k), v); } return map; } return parameterMap; } @Override public String getHeader(String name) { String header = super.getHeader(xssEncode(name)); if (StringUtils.isNotBlank(header)) { return xssEncode(header); } return header; } @Override public ServletInputStream getInputStream() throws IOException { // 请求头非json类型,直接返回,Content-Type != application/json if (!MediaType.APPLICATION_JSON_VALUE.equalsIgnoreCase(super.getHeader(HttpHeaders.CONTENT_TYPE))) { return super.getInputStream(); } // 请求流为空,直接返回 String io = IOUtils.toString(super.getInputStream(), "UTF-8"); if (StringUtils.isBlank(io)) { return super.getInputStream(); } // 执行 xss 过滤 io = xssEncode(io); // 将过滤结果封装成流 final ByteArrayInputStream bio = new ByteArrayInputStream(io.getBytes("UTF-8")); return new ServletInputStream() { @Override public boolean isFinished() { return true; } @Override public boolean isReady() { return true; } @Override public void setReadListener(ReadListener listener) { } @Override public int read() throws IOException { return bio.read(); } }; } private String xssEncode(String input) { return htmlFilter.filter(input); } @Override public String getParameter(String name) { String value = super.getParameter(xssEncode(name)); if (StringUtils.isNotBlank(value)) { return xssEncode(value); } return value; } @Override public String[] getParameterValues(String name) { String[] values = super.getParameterValues(xssEncode(name)); if (values == null || values.length == 0) { return null; } for (int i = 0; i < values.length; i++) { values[i] = xssEncode(values[i]); } return values; } /** * Constructs a request object wrapping the given request. * * @param request The request to wrap * @throws IllegalArgumentException if the request is null */ public XssHttpServletRequestWrapper(HttpServletRequest request) { super(request); this.orgRequest = request; } /** * 获取最原始的 request * @return */ public HttpServletRequest getOrgRequest() { return orgRequest; } /** * 获取最原始的 request * @param request * @return */ public static HttpServletRequest getOrgRequest(HttpServletRequest request) { if (request instanceof XssHttpServletRequestWrapper) { return ((XssHttpServletRequestWrapper)request).getOrgRequest(); } return request; } }
3、正式创建过滤器,使用我们定义的 HttpServletRequestWrapper的子类 包装类去替换掉它原来的 HttpServletRequest
package io.xiongdi.common.xss; import javax.servlet.*; import javax.servlet.http.HttpServletRequest; import java.io.IOException; /** * xss 过滤 * * @author wujiaxing * @date 2019-07-10 */ public class XssFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request); chain.doFilter(xssRequest, response); // 这里使用的是HttpServletRequest的子类
} @Override public void destroy() { } }
4、将过滤器配置给 spring boot
package io.xiongdi.config; import io.xiongdi.common.xss.XssFilter; import org.springframework.boot.web.servlet.FilterRegistrationBean; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import javax.servlet.DispatcherType; /** * @author wujiaxing * <p> * 过滤器配置 * </p> */ @Configuration public class FilterConfig { @Bean public FilterRegistrationBean xssFilterRegistration() { FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(); filterRegistrationBean.setFilter(new XssFilter()); filterRegistrationBean.addUrlPatterns("/*"); filterRegistrationBean.setDispatcherTypes(DispatcherType.REQUEST); filterRegistrationBean.setName("xssFilter"); return filterRegistrationBean; } }
注意路径配置成 /*
只要你不觉得尴尬,那尴尬的就是别人