Java tutorial
/* * RTSFetcher.java * This file is part of Freemail * Copyright (C) 2006,2007,2008 Dave Baker * Copyright (C) 2007,2008 Alexander Lehmann * * This program 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 2 of the License, or * (at your option) any later version. * * This program 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 this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ package org.freenetproject.freemail; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.PrintStream; import java.util.Date; import java.util.Calendar; import java.util.TimeZone; import java.math.BigInteger; import org.bouncycastle.crypto.digests.SHA256Digest; import org.bouncycastle.crypto.params.RSAKeyParameters; import org.bouncycastle.crypto.AsymmetricBlockCipher; import org.bouncycastle.crypto.engines.RSAEngine; import org.bouncycastle.crypto.InvalidCipherTextException; import org.bouncycastle.crypto.engines.AESEngine; import org.bouncycastle.crypto.params.KeyParameter; import org.bouncycastle.crypto.params.ParametersWithIV; import org.bouncycastle.crypto.paddings.PKCS7Padding; import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher; import org.bouncycastle.crypto.modes.CBCBlockCipher; import org.bouncycastle.crypto.DataLengthException; import org.freenetproject.freemail.fcp.ConnectionTerminatedException; import org.freenetproject.freemail.fcp.FCPException; import org.freenetproject.freemail.fcp.FCPFetchException; import org.freenetproject.freemail.fcp.HighLevelFCPClient; import org.freenetproject.freemail.support.io.LineReadingInputStream; import org.freenetproject.freemail.support.io.TooLongException; import org.freenetproject.freemail.utils.DateStringFactory; import org.freenetproject.freemail.utils.Logger; import org.freenetproject.freemail.utils.PropsFile; public class RTSFetcher implements SlotSaveCallback { private String rtskey; private File contact_dir; private static final int POLL_AHEAD = 3; private static final int PASSES_PER_DAY = 3; private static final int MAX_DAYS_BACK = 30; public static final String LOGFILE = "rtslog"; private static final int RTS_MAX_SIZE = 2 * 1024 * 1024; private static final String RTS_UNPROC_PREFIX = "unprocessed_rts"; private static final int RTS_MAX_ATTEMPTS = 15; private FreemailAccount account; RTSFetcher(String key, File ctdir, FreemailAccount acc) { this.rtskey = key; this.contact_dir = ctdir; this.account = acc; } public void poll() throws ConnectionTerminatedException, InterruptedException { this.fetch(); this.handle_unprocessed(); } private void handle_unprocessed() throws ConnectionTerminatedException, NumberFormatException, InterruptedException { File[] files = this.contact_dir.listFiles(); int i; for (i = 0; i < files.length; i++) { if (!files[i].getName().startsWith(RTS_UNPROC_PREFIX)) continue; if (this.handle_rts(files[i])) { files[i].delete(); } else { String[] parts = files[i].getName().split(",", 2); int tries; if (parts.length < 2) { tries = 0; } else { tries = Integer.parseInt(parts[1]); } tries++; if (tries > RTS_MAX_ATTEMPTS) { Logger.normal(this, "Maximum attempts at handling RTS reached - deleting RTS"); files[i].delete(); } else { File newname = new File(this.contact_dir, parts[0] + "," + tries); files[i].renameTo(newname); } } } } private void fetch() throws ConnectionTerminatedException, InterruptedException { int i; RTSLog log = new RTSLog(new File(this.contact_dir, LOGFILE)); for (i = 1 - MAX_DAYS_BACK; i <= 0; i++) { String datestr = DateStringFactory.getOffsetKeyString(i); if (log.getPasses(datestr) < PASSES_PER_DAY) { boolean successfulPoll = this.fetch_day(log, datestr); // don't count passes for today since more // mail may arrive if (i < 0 && successfulPoll) { log.incPasses(datestr); } } } TimeZone gmt = TimeZone.getTimeZone("GMT"); Calendar cal = Calendar.getInstance(gmt); cal.setTime(new Date()); cal.add(Calendar.DAY_OF_MONTH, 0 - MAX_DAYS_BACK); log.pruneBefore(cal.getTime()); } private static class MySlotSaveData { RTSLog log; String date; } /** * @return true if the day was sucessfully polled, false if there were network-type errors and the polling shouldn't count * as a valid check of that day's slots. */ private boolean fetch_day(RTSLog log, String date) throws ConnectionTerminatedException, InterruptedException { HighLevelFCPClient fcpcli; fcpcli = new HighLevelFCPClient(); String keybase; keybase = this.rtskey + date + "-"; MySlotSaveData cbdata = new MySlotSaveData(); cbdata.log = log; cbdata.date = date; NaturalSlotManager sm = new NaturalSlotManager(this, cbdata, log.getSlots(date)); sm.setPollAhead(POLL_AHEAD); int slot; boolean success = true; while ((slot = sm.getNextSlotNat()) > 0) { Logger.minor(this, "trying to fetch " + keybase + slot); try { File result = fcpcli.fetch(keybase + slot); Logger.normal(this, keybase + slot + ": got RTS!"); File rts_dest = new File(this.contact_dir, RTS_UNPROC_PREFIX + "-" + log.getAndIncUnprocNextId() + ",0"); // stick this message in the RTS 'inbox' if (result.renameTo(rts_dest)) { // provided that worked, we can move on to the next RTS message sm.slotUsed(); } } catch (FCPFetchException fe) { if (fe.isFatal()) { Logger.error(this, keybase + slot + ": fatal fetch error - marking slot as used."); sm.slotUsed(); } else if (fe.getCode() == FCPFetchException.ALL_DATA_NOT_FOUND) { // This could be the node not managing to find the CHK containing the actual data (since RTS messages are // over 1KB, the node will opaquely insert them as a KSK redirect to a CHK, since a KSK/SSK can only hold // 1KB of data). It could also be someone inserting dummy redirects to our RTS queue. We'll have to keep // checking it, but we have to check slots until we find some that are really empty, we'd never manage // to fetch anything if they are dead keys. Logger.error(this, keybase + slot + ": All Data not found - leaving slot in queue and will poll an extra key"); sm.incPollAhead(); } else if (fe.getCode() == FCPFetchException.DATA_NOT_FOUND || fe.getCode() == FCPFetchException.RECENTLY_FAILED) { Logger.minor(this, keybase + slot + ": no RTS."); } else if (fe.isNetworkError()) { // Freenet is having special moment. This doesn't count as a valid poll. success = false; } else { // We've covered most things above, so I think this should a fairly exceptional case. Let's log it at error. Logger.error(this, keybase + slot + ": other non-fatal fetch error:" + fe.getMessage()); } } catch (FCPException e) { Logger.error(this, "Unknown error while checking RTS: " + e.getMessage()); success = false; } } return success; } @Override public void saveSlots(String slots, Object userdata) { MySlotSaveData cbdata = (MySlotSaveData) userdata; cbdata.log.putSlots(cbdata.date, slots); } private boolean handle_rts(File rtsmessage) throws ConnectionTerminatedException, InterruptedException { // sanity check! if (!rtsmessage.exists()) return false; if (rtsmessage.length() > RTS_MAX_SIZE) { Logger.normal(this, "RTS Message is too large - discarding!"); return true; } // decrypt byte[] plaintext; try { plaintext = decrypt_rts(rtsmessage); } catch (IOException ioe) { Logger.normal(this, "Error reading RTS message!"); return false; } catch (InvalidCipherTextException icte) { Logger.normal(this, "Could not decrypt RTS message - discarding. " + icte.getMessage()); return true; } File rtsfile = null; byte[] their_encrypted_sig; int messagebytes = 0; LineReadingInputStream lis = null; PrintStream ps = null; try { rtsfile = File.createTempFile("rtstmp", "tmp", Freemail.getTempDir()); ByteArrayInputStream bis = new ByteArrayInputStream(plaintext); lis = new LineReadingInputStream(bis); ps = new PrintStream(new FileOutputStream(rtsfile)); String line; while (true) { try { line = lis.readLine(200, 200, false); } catch (TooLongException tle) { Logger.normal(this, "RTS message has lines that are too long. Discarding."); rtsfile.delete(); return true; } messagebytes += lis.getLastBytesRead(); if (line == null || line.equals("")) break; //FreemailLogger.normal(this, line); ps.println(line); } if (line == null) { // that's not right, we shouldn't have reached the end of the file, just the blank line before the signature Logger.normal(this, "Couldn't find signature on RTS message - ignoring!"); rtsfile.delete(); return true; } // read the rest of the file into a byte array. // will probably have extra stuff on the end because // the byte array returned by the decrypt function // isn't resized when we know how much plaintext // there is. It would be a waste of time, we know // we have to read exactly one RSA block's worth. their_encrypted_sig = new byte[bis.available()]; int totalread = 0; while (true) { int read = bis.read(their_encrypted_sig, totalread, bis.available()); if (read <= 0) break; totalread += read; } } catch (IOException ioe) { Logger.normal(this, "IO error whilst handling RTS message. " + ioe.getMessage()); ioe.printStackTrace(); if (rtsfile != null) rtsfile.delete(); return false; } finally { if (ps != null) { ps.close(); } if (lis != null) { try { lis.close(); } catch (IOException e) { Logger.error(this, "Caugth IOException while closing input", e); } } } PropsFile rtsprops = PropsFile.createPropsFile(rtsfile); try { validate_rts(rtsprops); } catch (Exception e) { Logger.normal(this, "RTS message does not contain vital information: " + e.getMessage() + " - discarding"); rtsfile.delete(); return true; } // verify the signature String their_mailsite = rtsprops.get("mailsite"); SHA256Digest sha256 = new SHA256Digest(); sha256.update(plaintext, 0, messagebytes); byte[] our_hash = new byte[sha256.getDigestSize()]; sha256.doFinal(our_hash, 0); HighLevelFCPClient fcpcli = new HighLevelFCPClient(); Logger.normal(this, "Trying to fetch sender's mailsite: " + their_mailsite); File msfile; try { msfile = fcpcli.fetch(their_mailsite); } catch (FCPFetchException fe) { // oh well, try again in a bit rtsfile.delete(); return false; } catch (FCPException e) { Logger.error(this, "Unknown error while checking sender's mailsite: " + e.getMessage()); //Try again later rtsfile.delete(); return false; } PropsFile mailsite = PropsFile.createPropsFile(msfile); String their_exponent = mailsite.get("asymkey.pubexponent"); String their_modulus = mailsite.get("asymkey.modulus"); if (their_exponent == null || their_modulus == null) { Logger.normal(this, "Mailsite fetched successfully but missing vital information! Discarding this RTS."); msfile.delete(); rtsfile.delete(); return true; } RSAKeyParameters their_pubkey = new RSAKeyParameters(false, new BigInteger(their_modulus, 32), new BigInteger(their_exponent, 32)); AsymmetricBlockCipher deccipher = new RSAEngine(); deccipher.init(false, their_pubkey); byte[] their_hash; try { their_hash = deccipher.processBlock(their_encrypted_sig, 0, deccipher.getInputBlockSize()); } catch (InvalidCipherTextException icte) { Logger.normal(this, "It was not possible to decrypt the signature of this RTS message. Discarding the RTS message."); msfile.delete(); rtsfile.delete(); return true; } // finally we can now check that our hash and their hash // match! if (their_hash.length < our_hash.length) { Logger.normal(this, "The signature of the RTS message is not valid (our hash: " + our_hash.length + "bytes, their hash: " + their_hash.length + "bytes. Discarding the RTS message."); msfile.delete(); rtsfile.delete(); return true; } int i; for (i = 0; i < our_hash.length; i++) { if (their_hash[i] != our_hash[i]) { Logger.normal(this, "The signature of the RTS message is not valid. Discarding the RTS message."); msfile.delete(); rtsfile.delete(); return true; } } Logger.normal(this, "Signature valid :)"); // the signature is valid! Hooray! // Now verify the message is for us if (!account.getIdentity().equals(rtsprops.get("to"))) { Logger.normal(this, "Recieved an RTS message that was not intended for the recipient. Discarding."); msfile.delete(); rtsfile.delete(); return true; } Logger.normal(this, "Original message intended for us :)"); //Clean up temp files if (!msfile.delete()) { Logger.error(this, "Couldn't delete fetched mailsite: " + msfile); } if (!rtsfile.delete()) { Logger.error(this, "Couldn't delete rts file: " + rtsfile); } account.getMessageHandler().createChannelFromRTS(rtsprops); return true; } private byte[] decrypt_rts(File rtsmessage) throws IOException, InvalidCipherTextException { // initialise our ciphers RSAKeyParameters ourprivkey = AccountManager.getPrivateKey(account.getProps()); AsymmetricBlockCipher deccipher = new RSAEngine(); deccipher.init(false, ourprivkey); PaddedBufferedBlockCipher aescipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(new AESEngine()), new PKCS7Padding()); // first n bytes will be an encrypted RSA block containting the // AES IV and Key. Read that. byte[] encrypted_params = new byte[deccipher.getInputBlockSize()]; int read = 0; FileInputStream fis = new FileInputStream(rtsmessage); try { while (read < encrypted_params.length) { read += fis.read(encrypted_params, read, encrypted_params.length - read); if (read < 0) break; } if (read < 0) { fis.close(); throw new InvalidCipherTextException("RTS Message too short"); } byte[] aes_iv_and_key = deccipher.processBlock(encrypted_params, 0, encrypted_params.length); KeyParameter kp = new KeyParameter(aes_iv_and_key, aescipher.getBlockSize(), aes_iv_and_key.length - aescipher.getBlockSize()); ParametersWithIV kpiv = new ParametersWithIV(kp, aes_iv_and_key, 0, aescipher.getBlockSize()); try { aescipher.init(false, kpiv); } catch (IllegalArgumentException iae) { fis.close(); throw new InvalidCipherTextException(iae.getMessage()); } byte[] plaintext = new byte[aescipher.getOutputSize((int) rtsmessage.length() - read)]; int ptbytes = 0; while (read < rtsmessage.length()) { byte[] buf = new byte[(int) rtsmessage.length() - read]; int thisread = fis.read(buf, 0, (int) rtsmessage.length() - read); ptbytes += aescipher.processBytes(buf, 0, thisread, plaintext, ptbytes); read += thisread; } try { aescipher.doFinal(plaintext, ptbytes); } catch (DataLengthException dle) { throw new InvalidCipherTextException(dle.getMessage()); } return plaintext; } finally { fis.close(); } } /* * Make sure an RTS file has all the right properties in it * If any are missing, throw an exception which says which are missing */ /* FIXME: Throw a different exception */ private void validate_rts(PropsFile rts) throws Exception { StringBuffer missing = new StringBuffer(); if (rts.get("mailsite") == null) { missing.append("mailsite, "); } else { String mailsite = rts.get("mailsite"); if (!FreenetURI.checkUSK(mailsite)) { Logger.error(this, "RTS contains malformed mailsite key: " + mailsite); /* FIXME: Throw a better exception */ throw new Exception(); } } if (rts.get("to") == null) { missing.append("to, "); } if (rts.get("channel") == null) { missing.append("channel, "); } else { String channel = rts.get("channel"); if (!FreenetURI.checkSSK(channel)) { Logger.error(this, "RTS contains malformed channel key: " + channel); /* FIXME: Throw a better exception */ throw new Exception(); } } if (rts.get("initiatorSlot") == null) { missing.append("initiatorSlot, "); } if (rts.get("responderSlot") == null) { missing.append("responderSlot, "); } if (missing.length() == 0) return; /* FIXME: Throw a better exception */ throw new Exception(missing.toString().substring(0, missing.length() - 2)); } }