1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/impl/io/AbstractMessageParser.java $
3 * $Revision: 576077 $
4 * $Date: 2007-09-16 04:50:22 -0700 (Sun, 16 Sep 2007) $
5 *
6 * ====================================================================
7 * Licensed to the Apache Software Foundation (ASF) under one
8 * or more contributor license agreements.  See the NOTICE file
9 * distributed with this work for additional information
10 * regarding copyright ownership.  The ASF licenses this file
11 * to you under the Apache License, Version 2.0 (the
12 * "License"); you may not use this file except in compliance
13 * with the License.  You may obtain a copy of the License at
14 *
15 *   http://www.apache.org/licenses/LICENSE-2.0
16 *
17 * Unless required by applicable law or agreed to in writing,
18 * software distributed under the License is distributed on an
19 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
20 * KIND, either express or implied.  See the License for the
21 * specific language governing permissions and limitations
22 * under the License.
23 * ====================================================================
24 *
25 * This software consists of voluntary contributions made by many
26 * individuals on behalf of the Apache Software Foundation.  For more
27 * information on the Apache Software Foundation, please see
28 * <http://www.apache.org/>.
29 *
30 */
31
32package org.apache.http.impl.io;
33
34import java.io.IOException;
35import java.util.ArrayList;
36
37import org.apache.http.Header;
38import org.apache.http.HttpException;
39import org.apache.http.HttpMessage;
40import org.apache.http.ParseException;
41import org.apache.http.ProtocolException;
42import org.apache.http.io.HttpMessageParser;
43import org.apache.http.io.SessionInputBuffer;
44import org.apache.http.message.LineParser;
45import org.apache.http.message.BasicLineParser;
46import org.apache.http.params.CoreConnectionPNames;
47import org.apache.http.params.HttpParams;
48import org.apache.http.util.CharArrayBuffer;
49
50/**
51 * Message parser base class.
52 *
53 * @author Michael Becke
54 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
55 */
56public abstract class AbstractMessageParser implements HttpMessageParser {
57
58    private final SessionInputBuffer sessionBuffer;
59    private final int maxHeaderCount;
60    private final int maxLineLen;
61    protected final LineParser lineParser;
62
63
64    public AbstractMessageParser(
65            final SessionInputBuffer buffer,
66            final LineParser parser,
67            final HttpParams params) {
68        super();
69        if (buffer == null) {
70            throw new IllegalArgumentException("Session input buffer may not be null");
71        }
72        if (params == null) {
73            throw new IllegalArgumentException("HTTP parameters may not be null");
74        }
75        this.sessionBuffer = buffer;
76        this.maxHeaderCount = params.getIntParameter(
77                CoreConnectionPNames.MAX_HEADER_COUNT, -1);
78        this.maxLineLen = params.getIntParameter(
79                CoreConnectionPNames.MAX_LINE_LENGTH, -1);
80        this.lineParser = (parser != null) ? parser : BasicLineParser.DEFAULT;
81    }
82
83    /**
84     * Parses HTTP headers from the data receiver stream according to the generic
85     * format as given in Section 3.1 of RFC 822, RFC-2616 Section 4 and 19.3.
86     *
87     * @param inbuffer Session input buffer
88     * @param maxHeaderCount maximum number of headers allowed. If the number
89     *  of headers received from the data stream exceeds maxCount value, an
90     *  IOException will be thrown. Setting this parameter to a negative value
91     *  or zero  will disable the check.
92     * @param maxLineLen maximum number of characters for a header line,
93     *                   including the continuation lines
94     * @return array of HTTP headers
95     *
96     * @throws HttpException
97     * @throws IOException
98     */
99    public static Header[] parseHeaders(
100            final SessionInputBuffer inbuffer,
101            int maxHeaderCount,
102            int maxLineLen,
103            LineParser parser)
104        throws HttpException, IOException {
105
106        if (inbuffer == null) {
107            throw new IllegalArgumentException("Session input buffer may not be null");
108        }
109        if (parser == null)
110            parser = BasicLineParser.DEFAULT;
111
112        ArrayList headerLines = new ArrayList();
113
114        CharArrayBuffer current = null;
115        CharArrayBuffer previous = null;
116        for (;;) {
117            if (current == null) {
118                current = new CharArrayBuffer(64);
119            } else {
120                current.clear();
121            }
122            int l = inbuffer.readLine(current);
123            if (l == -1 || current.length() < 1) {
124                break;
125            }
126            // Parse the header name and value
127            // Check for folded headers first
128            // Detect LWS-char see HTTP/1.0 or HTTP/1.1 Section 2.2
129            // discussion on folded headers
130            if ((current.charAt(0) == ' ' || current.charAt(0) == '\t') && previous != null) {
131                // we have continuation folded header
132                // so append value
133                int i = 0;
134                while (i < current.length()) {
135                    char ch = current.charAt(i);
136                    if (ch != ' ' && ch != '\t') {
137                        break;
138                    }
139                    i++;
140                }
141                if (maxLineLen > 0
142                        && previous.length() + 1 + current.length() - i > maxLineLen) {
143                    throw new IOException("Maximum line length limit exceeded");
144                }
145                previous.append(' ');
146                previous.append(current, i, current.length() - i);
147            } else {
148                headerLines.add(current);
149                previous = current;
150                current = null;
151            }
152            if (maxHeaderCount > 0 && headerLines.size() >= maxHeaderCount) {
153                throw new IOException("Maximum header count exceeded");
154            }
155        }
156        Header[] headers = new Header[headerLines.size()];
157        for (int i = 0; i < headerLines.size(); i++) {
158            CharArrayBuffer buffer = (CharArrayBuffer) headerLines.get(i);
159            try {
160                headers[i] = parser.parseHeader(buffer);
161            } catch (ParseException ex) {
162                throw new ProtocolException(ex.getMessage());
163            }
164        }
165        return headers;
166    }
167
168    protected abstract HttpMessage parseHead(SessionInputBuffer sessionBuffer)
169        throws IOException, HttpException, ParseException;
170
171    public HttpMessage parse() throws IOException, HttpException {
172        HttpMessage message = null;
173        try {
174            message = parseHead(this.sessionBuffer);
175        } catch (ParseException px) {
176            throw new ProtocolException(px.getMessage(), px);
177        }
178        Header[] headers = AbstractMessageParser.parseHeaders(
179                this.sessionBuffer,
180                this.maxHeaderCount,
181                this.maxLineLen,
182                this.lineParser);
183        message.setHeaders(headers);
184        return message;
185    }
186
187}
188