HttpHeaderReaderImpl.java

/*
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 * file and include the License file at packager/legal/LICENSE.txt.
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package com.sun.jersey.core.header.reader;

import java.text.ParseException;

/**
 *
 * @author Paul.Sandoz@Sun.Com
 */
/* package */ final class HttpHeaderReaderImpl extends HttpHeaderReader {

    private static final int TOKEN = 0;
    private static final int QUOTED_STRING = 1;
    private static final int COMMENT = 2;
    private static final int SEPARATOR = 3;
    private static final int CONTROL = 4;
    private static final char[] WHITE_SPACE = {'\t', '\r', '\n', ' '};
    private static final char[] SEPARATORS = {'(', ')', '<', '>', '@', ',', ';', ':', '\\', '"', '/', '[', ']', '?', '=', '{', '}', ' ', '\t'};
    private static final int[] EVENT_TABLE = createEventTable();

    private static int[] createEventTable() {
        int[] table = new int[128];

        // Token
        for (int i = 0; i < 127; i++) {
            table[i] = TOKEN;
        }

        // Separator
        for (char c : SEPARATORS) {
            table[c] = SEPARATOR;
        }

        // Comment
        table['('] = COMMENT;

        // QuotedString
        table['"'] = QUOTED_STRING;

        // Control
        for (int i = 0; i < 32; i++) {
            table[i] = CONTROL;
        }
        table[127] = CONTROL;

        // White space
        for (char c : WHITE_SPACE) {
            table[c] = -1;
        }

        return table;
    }

    private static final boolean[] IS_WHITE_SPACE = createWhiteSpaceTable();

    private static boolean[] createWhiteSpaceTable() {
        boolean[] table = new boolean[128];

        for (char c : WHITE_SPACE) {
            table[c] = true;
        }

        return table;
    }

    private static final boolean[] IS_TOKEN = createTokenTable();

    private static boolean[] createTokenTable() {
        boolean[] table = new boolean[128];

        for (int i = 0; i < 128; i++) {
            table[i] = (EVENT_TABLE[i] == TOKEN);
        }

        return table;
    }
    
    private String header;

    private boolean processComments;

    private int index;

    private int length;

    private Event event;

    private String value;

    public HttpHeaderReaderImpl(String header, boolean processComments) {
        this.header = (header == null) ? "" : header;
        this.processComments = processComments;
        this.index = 0;
        this.length = this.header.length();
    }

    public HttpHeaderReaderImpl(String header) {
        this(header, false);
    }

    public boolean hasNext() {
        return skipWhiteSpace();
    }

    public boolean hasNextSeparator(char separator, boolean skipWhiteSpace) {
        if (skipWhiteSpace) {
            skipWhiteSpace();
        }

        if (index >= length) {
            return false;
        }

        char c = header.charAt(index);
        return (EVENT_TABLE[c] == SEPARATOR)
                ? c == separator : false;
    }

    public String nextSeparatedString(char startSeparator, char endSeparator) throws ParseException {
        nextSeparator(startSeparator);
        final int start = index;
        for (; index < length; index++) {
            if (header.charAt(index) == endSeparator) {
                break;
            }
        }

        if (start == index) {
            // no token between separators
            throw new ParseException("No characters between the separators " +
                    "'" + startSeparator + "' and '" + endSeparator + "'", index);
        } else if (index == length) {
            // no end separator
            throw new ParseException("No end separator '" + endSeparator + "'", index);
        }

        event = Event.Token;
        return value = header.substring(start, index++);
    }

    public Event next() throws ParseException {
        return event = process(getNextCharacter(true));
    }

    public Event next(boolean skipWhiteSpace) throws ParseException {
        return event = process(getNextCharacter(skipWhiteSpace));
    }

    public Event getEvent() {
        return event;
    }

    public String getEventValue() {
        return value;
    }

    public String getRemainder() {
        return (index < length) ? header.substring(index) : null;
    }

    public int getIndex() {
        return index;
    }

    private boolean skipWhiteSpace() {
        for (; index < length; index++) {
            if (!isWhiteSpace(header.charAt(index))) {
                return true;
            }
        }

        return false;
    }

    private char getNextCharacter(boolean skipWhiteSpace) throws ParseException {
        if (skipWhiteSpace) {
            skipWhiteSpace();
        }

        if (index >= length) {
            throw new ParseException("End of header", index);
        }

        return header.charAt(index);
    }

    private Event process(char c) throws ParseException {
        if (c > 127) {
            index++;
            return Event.Control;
        }

        switch (EVENT_TABLE[c]) {
            case TOKEN: {
                final int start = index;
                for (index++; index < length; index++) {
                    if (!isToken(header.charAt(index))) {
                        break;
                    }
                }
                value = header.substring(start, index);
                return Event.Token;
            }
            case QUOTED_STRING:
                processQuotedString();
                return Event.QuotedString;
            case COMMENT:
                if (!processComments) {
                    throw new ParseException("Comments are not allowed", index);
                }

                processComment();
                return Event.Comment;
            case SEPARATOR:
                index++;
                value = String.valueOf(c);
                return Event.Separator;
            case CONTROL:
                index++;
                value = String.valueOf(c);
                return Event.Control;
            default:
                // White space
                throw new ParseException("White space not allowed", index);
        }
    }

    private void processComment() throws ParseException {
        boolean filter = false;
        int nesting;
        int start;
        for (start = ++index  , nesting = 1;
                nesting > 0 && index < length;
                index++) {
            char c = header.charAt(index);
            if (c == '\\') {
                index++;
                filter = true;
            } else if (c == '\r') {
                filter = true;
            } else if (c == '(') {
                nesting++;
            } else if (c == ')') {
                nesting--;
            }
        }
        if (nesting != 0) {
            throw new ParseException("Unbalanced comments", index);
        }

        value = (filter)
                ? filterToken(header, start, index - 1)
                : header.substring(start, index - 1);
    }

    private void processQuotedString() throws ParseException {
        boolean filter = false;
        for (int start = ++index; index < length; index++) {
            char c = this.header.charAt(index);
            if (c == '\\') {
                index++;
                filter = true;
            } else if (c == '\r') {
                filter = true;
            } else if (c == '"') {
                value = (filter)
                        ? filterToken(header, start, index)
                        : header.substring(start, index);

                index++;
                return;
            }
        }

        throw new ParseException("Unbalanced quoted string", index);
    }

    private boolean isWhiteSpace(char c) {
        return (c < 128 && IS_WHITE_SPACE[c]);
    }

    private boolean isToken(char c) {
        return (c < 128 && IS_TOKEN[c]);
    }

    private static String filterToken(String s, int start, int end) {
        StringBuffer sb = new StringBuffer();
        char c;
        boolean gotEscape = false;
        boolean gotCR = false;

        for (int i = start; i < end; i++) {
            c = s.charAt(i);
            if (c == '\n' && gotCR) {
                // This LF is part of an unescaped
                // CRLF sequence (i.e, LWSP). Skip it.
                gotCR = false;
                continue;
            }

            gotCR = false;
            if (!gotEscape) {
                // Previous character was NOT '\'
                if (c == '\\') { // skip this character
                    gotEscape = true;
                } else if (c == '\r') { // skip this character
                    gotCR = true;
                } else { // append this character
                    sb.append(c);
                }
            } else {
                // Previous character was '\'. So no need to
                // bother with any special processing, just
                // append this character
                sb.append(c);
                gotEscape = false;
            }
        }
        return sb.toString();
    }
}