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| 1 | /* | ||
| 2 | * Copyright (c) 1994, 1995, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package sun.net; | ||
| 27 | |||
| 28 | import java.io.*; | ||
| 29 | |||
| 30 | /** | ||
| 31 | * This class provides input and output streams for telnet clients. | ||
| 32 | * This class overrides read to do CRLF processing as specified in | ||
| 33 | * RFC 854. The class assumes it is running on a system where lines | ||
| 34 | * are terminated with a single newline <LF> character. | ||
| 35 | * | ||
| 36 | * This is the relevant section of RFC 824 regarding CRLF processing: | ||
| 37 | * | ||
| 38 | * <pre> | ||
| 39 | * The sequence "CR LF", as defined, will cause the NVT to be | ||
| 40 | * positioned at the left margin of the next print line (as would, | ||
| 41 | * for example, the sequence "LF CR"). However, many systems and | ||
| 42 | * terminals do not treat CR and LF independently, and will have to | ||
| 43 | * go to some effort to simulate their effect. (For example, some | ||
| 44 | * terminals do not have a CR independent of the LF, but on such | ||
| 45 | * terminals it may be possible to simulate a CR by backspacing.) | ||
| 46 | * Therefore, the sequence "CR LF" must be treated as a single "new | ||
| 47 | * line" character and used whenever their combined action is | ||
| 48 | * intended; the sequence "CR NUL" must be used where a carriage | ||
| 49 | * return alone is actually desired; and the CR character must be | ||
| 50 | * avoided in other contexts. This rule gives assurance to systems | ||
| 51 | * which must decide whether to perform a "new line" function or a | ||
| 52 | * multiple-backspace that the TELNET stream contains a character | ||
| 53 | * following a CR that will allow a rational decision. | ||
| 54 | * | ||
| 55 | * Note that "CR LF" or "CR NUL" is required in both directions | ||
| 56 | * (in the default ASCII mode), to preserve the symmetry of the | ||
| 57 | * NVT model. Even though it may be known in some situations | ||
| 58 | * (e.g., with remote echo and suppress go ahead options in | ||
| 59 | * effect) that characters are not being sent to an actual | ||
| 60 | * printer, nonetheless, for the sake of consistency, the protocol | ||
| 61 | * requires that a NUL be inserted following a CR not followed by | ||
| 62 | * a LF in the data stream. The converse of this is that a NUL | ||
| 63 | * received in the data stream after a CR (in the absence of | ||
| 64 | * options negotiations which explicitly specify otherwise) should | ||
| 65 | * be stripped out prior to applying the NVT to local character | ||
| 66 | * set mapping. | ||
| 67 | * </pre> | ||
| 68 | * | ||
| 69 | * @author Jonathan Payne | ||
| 70 | */ | ||
| 71 | |||
| 72 | public class TelnetInputStream extends FilterInputStream { | ||
| 73 | /** If stickyCRLF is true, then we're a machine, like an IBM PC, | ||
| 74 | where a Newline is a CR followed by LF. On UNIX, this is false | ||
| 75 | because Newline is represented with just a LF character. */ | ||
| 76 | boolean stickyCRLF = false; | ||
| 77 | boolean seenCR = false; | ||
| 78 | |||
| 79 | public boolean binaryMode = false; | ||
| 80 | |||
| 81 | public TelnetInputStream(InputStream fd, boolean binary) { | ||
| 82 | super(fd); | ||
| 83 | binaryMode = binary; | ||
| 84 | } | ||
| 85 | |||
| 86 | public void setStickyCRLF(boolean on) { | ||
| 87 | stickyCRLF = on; | ||
| 88 | } | ||
| 89 | |||
| 90 | public int read() throws IOException { | ||
| 91 | if (binaryMode) | ||
| 92 | return super.read(); | ||
| 93 | |||
| 94 | int c; | ||
| 95 | |||
| 96 | /* If last time we determined we saw a CRLF pair, and we're | ||
| 97 | not turning that into just a Newline (that is, we're | ||
| 98 | stickyCRLF), then return the LF part of that sticky | ||
| 99 | pair now. */ | ||
| 100 | |||
| 101 | if (seenCR) { | ||
| 102 | seenCR = false; | ||
| 103 | return '\n'; | ||
| 104 | } | ||
| 105 | |||
| 106 | if ((c = super.read()) == '\r') { /* CR */ | ||
| 107 | switch (c = super.read()) { | ||
| 108 | default: | ||
| 109 | case -1: /* this is an error */ | ||
| 110 | throw new TelnetProtocolException("misplaced CR in input"); | ||
| 111 | |||
| 112 | case 0: /* NUL - treat CR as CR */ | ||
| 113 | return '\r'; | ||
| 114 | |||
| 115 | case '\n': /* CRLF - treat as NL */ | ||
| 116 | if (stickyCRLF) { | ||
| 117 | seenCR = true; | ||
| 118 | return '\r'; | ||
| 119 | } else { | ||
| 120 | return '\n'; | ||
| 121 | } | ||
| 122 | } | ||
| 123 | } | ||
| 124 | return c; | ||
| 125 | } | ||
| 126 | |||
| 127 | /** read into a byte array */ | ||
| 128 | public int read(byte bytes[]) throws IOException { | ||
| 129 | return read(bytes, 0, bytes.length); | ||
| 130 | } | ||
| 131 | |||
| 132 | /** | ||
| 133 | * Read into a byte array at offset <i>off</i> for length <i>length</i> | ||
| 134 | * bytes. | ||
| 135 | */ | ||
| 136 | public int read(byte bytes[], int off, int length) throws IOException { | ||
| 137 | if (binaryMode) | ||
| 138 | return super.read(bytes, off, length); | ||
| 139 | |||
| 140 | int c; | ||
| 141 | int offStart = off; | ||
| 142 | |||
| 143 | while (--length >= 0) { | ||
| 144 | c = read(); | ||
| 145 | if (c == -1) | ||
| 146 | break; | ||
| 147 | bytes[off++] = (byte)c; | ||
| 148 | } | ||
| 149 | return (off > offStart) ? off - offStart : -1; | ||
| 150 | } | ||
| 151 | } | ||