DefaultFilterChainManager.java

package com.hwlcn.security.web.filter.mgt;

import com.hwlcn.security.config.ConfigurationException;
import com.hwlcn.security.util.CollectionUtils;
import com.hwlcn.security.util.Nameable;
import com.hwlcn.security.util.StringUtils;
import com.hwlcn.security.web.filter.PathConfigProcessor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;


public class DefaultFilterChainManager implements FilterChainManager {

    private static transient final Logger log = LoggerFactory.getLogger(DefaultFilterChainManager.class);

    private FilterConfig filterConfig;

    private Map<String, Filter> filters;
    private Map<String, NamedFilterList> filterChains;
    public DefaultFilterChainManager() {
        this.filters = new LinkedHashMap<String, Filter>();
        this.filterChains = new LinkedHashMap<String, NamedFilterList>();
        addDefaultFilters(false);
    }

    public DefaultFilterChainManager(FilterConfig filterConfig) {
        this.filters = new LinkedHashMap<String, Filter>();
        this.filterChains = new LinkedHashMap<String, NamedFilterList>();
        setFilterConfig(filterConfig);
        addDefaultFilters(true);
    }

    public FilterConfig getFilterConfig() {
        return filterConfig;
    }

    public void setFilterConfig(FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
    }

    public Map<String, Filter> getFilters() {
        return filters;
    }

    public void setFilters(Map<String, Filter> filters) {
        this.filters = filters;
    }

    public Map<String, NamedFilterList> getFilterChains() {
        return filterChains;
    }

    public void setFilterChains(Map<String, NamedFilterList> filterChains) {
        this.filterChains = filterChains;
    }

    public Filter getFilter(String name) {
        return this.filters.get(name);
    }

    public void addFilter(String name, Filter filter) {
        addFilter(name, filter, false);
    }

    public void addFilter(String name, Filter filter, boolean init) {
        addFilter(name, filter, init, true);
    }

    public void createChain(String chainName, String chainDefinition) {
        if (!StringUtils.hasText(chainName)) {
            throw new NullPointerException("chainName cannot be null or empty.");
        }
        if (!StringUtils.hasText(chainDefinition)) {
            throw new NullPointerException("chainDefinition cannot be null or empty.");
        }

        if (log.isDebugEnabled()) {
            log.debug("Creating chain [" + chainName + "] from String definition [" + chainDefinition + "]");
        }


        String[] filterTokens = splitChainDefinition(chainDefinition);
        for (String token : filterTokens) {
            String[] nameConfigPair = toNameConfigPair(token);

            addToChain(chainName, nameConfigPair[0], nameConfigPair[1]);
        }
    }


    protected String[] splitChainDefinition(String chainDefinition) {
        return StringUtils.split(chainDefinition, StringUtils.DEFAULT_DELIMITER_CHAR, '[', ']', true, true);
    }

     protected String[] toNameConfigPair(String token) throws ConfigurationException {

        try {
            String[] pair = token.split("\\[", 2);
            String name = StringUtils.clean(pair[0]);

            if (name == null) {
                throw new IllegalArgumentException("Filter name not found for filter chain definition token: " + token);
            }
            String config = null;

            if (pair.length == 2) {
                config = StringUtils.clean(pair[1]);
                config = config.substring(0, config.length() - 1);
                config = StringUtils.clean(config);

                if (config != null && config.startsWith("\"") && config.endsWith("\"")) {
                    String stripped = config.substring(1, config.length() - 1);
                    stripped = StringUtils.clean(stripped);

                    if (stripped != null && stripped.indexOf('"') == -1) {
                        config = stripped;
                    }
                }
            }

            return new String[]{name, config};

        } catch (Exception e) {
            String msg = "Unable to parse filter chain definition token: " + token;
            throw new ConfigurationException(msg, e);
        }
    }

    protected void addFilter(String name, Filter filter, boolean init, boolean overwrite) {
        Filter existing = getFilter(name);
        if (existing == null || overwrite) {
            if (filter instanceof Nameable) {
                ((Nameable) filter).setName(name);
            }
            if (init) {
                initFilter(filter);
            }
            this.filters.put(name, filter);
        }
    }

    public void addToChain(String chainName, String filterName) {
        addToChain(chainName, filterName, null);
    }

    public void addToChain(String chainName, String filterName, String chainSpecificFilterConfig) {
        if (!StringUtils.hasText(chainName)) {
            throw new IllegalArgumentException("chainName cannot be null or empty.");
        }
        Filter filter = getFilter(filterName);
        if (filter == null) {
            throw new IllegalArgumentException("There is no filter with name '" + filterName +
                    "' to apply to chain [" + chainName + "] in the pool of available Filters.  Ensure a " +
                    "filter with that name/path has first been registered with the addFilter method(s).");
        }

        applyChainConfig(chainName, filter, chainSpecificFilterConfig);

        NamedFilterList chain = ensureChain(chainName);
        chain.add(filter);
    }

    protected void applyChainConfig(String chainName, Filter filter, String chainSpecificFilterConfig) {
        if (log.isDebugEnabled()) {
            log.debug("Attempting to apply path [" + chainName + "] to filter [" + filter + "] " +
                    "with config [" + chainSpecificFilterConfig + "]");
        }
        if (filter instanceof PathConfigProcessor) {
            ((PathConfigProcessor) filter).processPathConfig(chainName, chainSpecificFilterConfig);
        } else {
            if (StringUtils.hasText(chainSpecificFilterConfig)) {
                //they specified a filter configuration, but the Filter doesn't implement PathConfigProcessor
                //this is an erroneous config:
                String msg = "chainSpecificFilterConfig was specified, but the underlying " +
                        "Filter instance is not an 'instanceof' " +
                        PathConfigProcessor.class.getName() + ".  This is required if the filter is to accept " +
                        "chain-specific configuration.";
                throw new ConfigurationException(msg);
            }
        }
    }

    protected NamedFilterList ensureChain(String chainName) {
        NamedFilterList chain = getChain(chainName);
        if (chain == null) {
            chain = new SimpleNamedFilterList(chainName);
            this.filterChains.put(chainName, chain);
        }
        return chain;
    }

    public NamedFilterList getChain(String chainName) {
        return this.filterChains.get(chainName);
    }

    public boolean hasChains() {
        return !CollectionUtils.isEmpty(this.filterChains);
    }

    public Set<String> getChainNames() {
        return this.filterChains != null ? this.filterChains.keySet() : Collections.EMPTY_SET;
    }

    public FilterChain proxy(FilterChain original, String chainName) {
        NamedFilterList configured = getChain(chainName);
        if (configured == null) {
            String msg = "There is no configured chain under the name/key [" + chainName + "].";
            throw new IllegalArgumentException(msg);
        }
        return configured.proxy(original);
    }

    protected void initFilter(Filter filter) {
        FilterConfig filterConfig = getFilterConfig();
        if (filterConfig == null) {
            throw new IllegalStateException("FilterConfig attribute has not been set.  This must occur before filter " +
                    "initialization can occur.");
        }
        try {
            filter.init(filterConfig);
        } catch (ServletException e) {
            throw new ConfigurationException(e);
        }
    }

    protected void addDefaultFilters(boolean init) {
        for (DefaultFilter defaultFilter : DefaultFilter.values()) {
            addFilter(defaultFilter.name(), defaultFilter.newInstance(), init, false);
        }
    }
}