SambaUncPathnameMapper.java

/*
* Copyright 2012, CMM, University of Queensland.
*
* This file is part of Paul.
*
* Paul is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Paul is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Paul. If not, see <http://www.gnu.org/licenses/>.
*/

package au.edu.uq.cmm.paul.watcher;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.ini4j.Ini;
import org.ini4j.InvalidFileFormatException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * An UNC path mapper for use on a Samba fileserver.  This reads the Samba
 * configuration file to figure out what the locally hosted shares are.
 * 
 * @author scrawley
 */
public class SambaUncPathnameMapper implements UncPathnameMapper {
    public static final String DEFAULT_SMB_CONF_PATHNAME = "/etc/samba/smb.conf";
    
    private static final Logger LOG = 
            LoggerFactory.getLogger(SambaUncPathnameMapper.class);
    private static final Pattern UNC_PATTERN = 
            Pattern.compile("//([^/]+)/([^/]+)(?:/+(.*))?");
    private Map<String, File> shareMap = new HashMap<String, File>();
    private Set<String> hostNames;
    
    public SambaUncPathnameMapper() 
            throws InvalidFileFormatException, IOException {
        this(DEFAULT_SMB_CONF_PATHNAME);
    }

    public SambaUncPathnameMapper(String smbConfFileName) 
            throws InvalidFileFormatException, IOException {
        initShareMap(smbConfFileName);
        initHostnames();
    }

    /**
     * Configure the set of Strings that we'll recognize as our hostname
     * an UNC pathname.
     * 
     * @throws UnknownHostException
     */
    private void initHostnames() throws UnknownHostException {
        // Note: this will only give us the primary hostname & IP address.  
        // DNS aliases and secondary IP addresses won't show up.  (If 
        // this is a problem we may need to configure the 'hostnames' 
        // set manually.)
        LOG.debug("Figuring out our hostnames");
        hostNames = new HashSet<String>();
        InetAddress host = InetAddress.getLocalHost();
        String hostAddr = host.getHostAddress();
        String hostName = host.getHostName();
        String canonicalHostName = host.getCanonicalHostName();
        hostNames.add(hostAddr);
        if (hostNames.add(hostName)) {
            int firstDot = hostName.indexOf(".");
            if (firstDot > 0) {
                hostNames.add(hostName.substring(0, firstDot));
            }
        }
        if (hostNames.add(canonicalHostName)) {
            int firstDot = canonicalHostName.indexOf(".");
            if (firstDot > 0) {
                hostNames.add(canonicalHostName.substring(0, firstDot));
            }
        }
        LOG.info("The following hostnames will be recognized " +
        		"as 'us' by the share mapper: " + hostNames);
    }

    /**
     * Load the SMB share mapping from the Samba config file.
     * 
     * @param smbConfFileName the pathname of the config file.
     * @throws FileNotFoundException
     * @throws IOException
     * @throws InvalidFileFormatException
     */
    private void initShareMap(String smbConfFileName)
            throws FileNotFoundException, IOException,
            InvalidFileFormatException {
        FileInputStream is = new FileInputStream(smbConfFileName);
        try {
            LOG.debug("Loading share map from Samba config file - " + smbConfFileName);
            Ini ini = new Ini();
            ini.load(is);
            for (String section : ini.keySet()) {
                if (section.equals("global")) {
                    continue;
                }
                String path = ini.get(section, "path");
                if (path == null) {
                    continue;
                }
                File dir = new File(path);
                if (!dir.exists() || !dir.isDirectory()) {
                    LOG.info("Ignoring share '" + section + 
                            "' because the mapped object '" + dir +
                            "' is not an existing directory");
                    continue;
                }
                LOG.debug("Share '" + section + "' maps to directory " + dir);
                shareMap.put(section, dir);
            }
        } finally {
            is.close();
        }
    }
    

    @Override
    public File mapUncPathname(String uncPathname) {
        String canonicalUncPathname = uncPathname.replace('\\', '/');
        Matcher matcher = UNC_PATTERN.matcher(canonicalUncPathname);
        if (!matcher.matches()) {
            LOG.info("Invalid UNC path: '" + canonicalUncPathname + "'");
            return null;
        }
        if (!hostNames.contains(matcher.group(1))) {
            LOG.info("UNC path '" + canonicalUncPathname + "'s hostname is not us");
            return null;
        }
        File sharePath = shareMap.get(matcher.group(2));
        if (sharePath == null) {
            LOG.info("UNC path '" + canonicalUncPathname + "'s share is not known");
            return null;
        }
        if (matcher.group(3) == null) {
            return sharePath;
        } else {
            return new File(sharePath, matcher.group(3));
        }
    }

}