Java tutorial
/* * SONEWS News Server * Copyright (C) 2009-2015 Christian Lins <christian@lins.me> * * 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 3 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, see <http://www.gnu.org/licenses/>. */ package org.sonews.daemon.command; import java.io.IOException; import java.util.List; import org.sonews.daemon.NNTPConnection; import org.sonews.util.Log; import org.sonews.storage.Article; import org.sonews.storage.ArticleHead; import org.sonews.storage.Headers; import org.sonews.storage.StorageBackendException; import org.sonews.util.Pair; import org.springframework.stereotype.Component; /** * Class handling the OVER/XOVER command. * * Description of the XOVER command: * * <pre> * XOVER [range] * * The XOVER command returns information from the overview * database for the article(s) specified. * * The optional range argument may be any of the following: * an article number * an article number followed by a dash to indicate * all following * an article number followed by a dash followed by * another article number * * If no argument is specified, then information from the * current article is displayed. Successful responses start * with a 224 response followed by the overview information * for all matched messages. Once the output is complete, a * period is sent on a line by itself. If no argument is * specified, the information for the current article is * returned. A news group must have been selected earlier, * else a 412 error response is returned. If no articles are * in the range specified, a 420 error response is returned * by the server. A 502 response will be returned if the * client only has permission to transfer articles. * * Each line of output will be formatted with the article number, * followed by each of the headers in the overview database or the * article itself (when the data is not available in the overview * database) for that article separated by a tab character. The * sequence of fields must be in this order: subject, author, * date, message-id, references, byte count, and line count. Other * optional fields may follow line count. Other optional fields may * follow line count. These fields are specified by examining the * response to the LIST OVERVIEW.FMT command. Where no data exists, * a null field must be provided (i.e. the output will have two tab * characters adjacent to each other). Servers should not output * fields for articles that have been removed since the XOVER database * was created. * * The LIST OVERVIEW.FMT command should be implemented if XOVER * is implemented. A client can use LIST OVERVIEW.FMT to determine * what optional fields and in which order all fields will be * supplied by the XOVER command. * * Note that any tab and end-of-line characters in any header * data that is returned will be converted to a space character. * * Responses: * * 224 Overview information follows * 412 No news group current selected * 420 No article(s) selected * 502 no permission * * OVER defines additional responses: * * First form (message-id specified) * 224 Overview information follows (multi-line) * 430 No article with that message-id * * Second form (range specified) * 224 Overview information follows (multi-line) * 412 No newsgroup selected * 423 No articles in that range * * Third form (current article number used) * 224 Overview information follows (multi-line) * 412 No newsgroup selected * 420 Current article number is invalid * * </pre> * * @author Christian Lins * @since sonews/0.5.0 */ @Component public class OverCommand implements Command { public static final int MAX_LINES_PER_DBREQUEST = 200; @Override public String[] getSupportedCommandStrings() { return new String[] { "OVER", "XOVER" }; } @Override public boolean hasFinished() { return true; } @Override public String impliedCapability() { return null; } @Override public boolean isStateful() { return false; } @Override public void processLine(NNTPConnection conn, final String line, byte[] raw) throws IOException, StorageBackendException { if (conn.getCurrentGroup() == null) { conn.println("412 no newsgroup selected"); } else { String[] command = line.split(" "); // If no parameter was specified, show information about // the currently selected article(s) if (command.length == 1) { final Article art = conn.getCurrentArticle(); if (art == null) { conn.println("420 no article(s) selected"); return; } conn.println(buildOverview(art, -1)); } // otherwise print information about the specified range else { long artStart; long artEnd = conn.getCurrentGroup().getLastArticleNumber(); String[] nums = command[1].split("-"); if (nums.length >= 1) { try { artStart = Integer.parseInt(nums[0]); } catch (NumberFormatException e) { Log.get().info(e.getMessage()); artStart = Integer.parseInt(command[1]); } } else { artStart = conn.getCurrentGroup().getFirstArticleNumber(); } if (nums.length >= 2) { try { artEnd = Integer.parseInt(nums[1]); } catch (NumberFormatException e) { e.printStackTrace(); } } if (artStart > artEnd) { if (command[0].equalsIgnoreCase("OVER")) { conn.println("423 no articles in that range"); } else { conn.println("224 (empty) overview information follows:"); conn.println("."); } } else { for (long n = artStart; n <= artEnd; n += MAX_LINES_PER_DBREQUEST) { long nEnd = Math.min(n + MAX_LINES_PER_DBREQUEST - 1, artEnd); List<Pair<Long, ArticleHead>> articleHeads = conn.getCurrentGroup().getArticleHeads(n, nEnd); if (articleHeads.isEmpty() && n == artStart && command[0].equalsIgnoreCase("OVER")) { // This reply is only valid for OVER, not for XOVER // command conn.println("423 no articles in that range"); return; } else if (n == artStart) { // XOVER replies this although there is no data // available conn.println("224 overview information follows"); } for (Pair<Long, ArticleHead> article : articleHeads) { String overview = buildOverview(article.getB(), article.getA()); conn.println(overview); } } // for conn.println("."); } } } } private String buildOverview(ArticleHead art, long nr) { StringBuilder overview = new StringBuilder(); overview.append(nr); overview.append('\t'); String subject = art.getHeader(Headers.SUBJECT)[0]; if ("".equals(subject)) { subject = "<empty>"; } overview.append(escapeString(subject)); overview.append('\t'); overview.append(escapeString(art.getHeader(Headers.FROM)[0])); overview.append('\t'); overview.append(escapeString(art.getHeader(Headers.DATE)[0])); overview.append('\t'); overview.append(escapeString(art.getHeader(Headers.MESSAGE_ID)[0])); overview.append('\t'); overview.append(escapeString(art.getHeader(Headers.REFERENCES)[0])); overview.append('\t'); String bytes = art.getHeader(Headers.BYTES)[0]; if ("".equals(bytes)) { bytes = "0"; } overview.append(escapeString(bytes)); overview.append('\t'); String lines = art.getHeader(Headers.LINES)[0]; if ("".equals(lines)) { lines = "0"; } overview.append(escapeString(lines)); overview.append('\t'); overview.append(escapeString(art.getHeader(Headers.XREF)[0])); // Remove trailing tabs if some data is empty return overview.toString().trim(); } private String escapeString(String str) { String nstr = str.replace("\r", ""); nstr = nstr.replace('\n', ' '); nstr = nstr.replace('\t', ' '); return nstr.trim(); } }