/*
 * Copyright (c) 2011, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.grizzly.http.ajp;

import static org.glassfish.grizzly.http.util.HttpCodecUtils.getLongAsBuffer;
import static org.glassfish.grizzly.http.util.HttpCodecUtils.put;
import static org.glassfish.grizzly.http.util.HttpCodecUtils.resizeBuffer;

import java.io.IOException;

import org.glassfish.grizzly.Buffer;
import org.glassfish.grizzly.http.HttpRequestPacket;
import org.glassfish.grizzly.http.HttpResponsePacket;
import org.glassfish.grizzly.http.util.Ascii;
import org.glassfish.grizzly.http.util.BufferChunk;
import org.glassfish.grizzly.http.util.DataChunk;
import org.glassfish.grizzly.http.util.HexUtils;
import org.glassfish.grizzly.http.util.HttpUtils;
import org.glassfish.grizzly.http.util.MimeHeaders;
import org.glassfish.grizzly.memory.Buffers;
import org.glassfish.grizzly.memory.CompositeBuffer;
import org.glassfish.grizzly.memory.MemoryManager;
import org.glassfish.grizzly.ssl.SSLSupport;

Utility method for Ajp message parsing and serialization.
Author:
Alexey Stashok/**
 * Utility method for Ajp message parsing and serialization.
 *
 * @author Alexey Stashok
 */
final class AjpMessageUtils {

    private static final int[] DEC = HexUtils.getDecBytes();
    private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];

    static void decodeRequest(final Buffer requestContent, final AjpHttpRequest req, final boolean tomcatAuthentication) throws IOException {
        // FORWARD_REQUEST handler

        int offset = requestContent.position();

        // Translate the HTTP method code to a String.
        byte methodCode = requestContent.get(offset++);
        if (methodCode != AjpConstants.SC_M_JK_STORED) {
            String mName = AjpConstants.methodTransArray[methodCode - 1];
            req.getMethodDC().setString(mName);
        }

        offset = getBytesToDataChunk(requestContent, offset, req.getProtocolDC());
        final int requestURILen = readShort(requestContent, offset);
        if (!isNullLength(requestURILen)) {
            req.getRequestURIRef().init(requestContent, offset + 2, offset + 2 + requestURILen);
        }
        // Don't forget to skip the terminating \0 (that's why "+ 1")
        offset += 2 + requestURILen + 1;

        offset = getBytesToDataChunk(requestContent, offset, req.remoteAddr());

        offset = getBytesToDataChunk(requestContent, offset, req.remoteHostRaw());

        offset = getBytesToDataChunk(requestContent, offset, req.localName());

        req.setLocalPort(readShort(requestContent, offset));
        offset += 2;

        final boolean isSSL = requestContent.get(offset++) != 0;
        req.setSecure(isSSL);
        req.getResponse().setSecure(isSSL);

        offset = decodeHeaders(requestContent, offset, req);

        decodeAttributes(requestContent, offset, req, tomcatAuthentication);

        req.setUnparsedHostHeader(req.getHeaders().getValue("host"));
    }

    private static int decodeAttributes(final Buffer requestContent, int offset, final AjpHttpRequest req, final boolean tomcatAuthentication) {

        final DataChunk tmpDataChunk = req.tmpDataChunk;

        boolean moreAttr = true;

        while (moreAttr) {
            final byte attributeCode = requestContent.get(offset++);
            if (attributeCode == AjpConstants.SC_A_ARE_DONE) {
                return offset;
            }

            /*
             * Special case ( XXX in future API make it separate type !)
             */
            if (attributeCode == AjpConstants.SC_A_SSL_KEY_SIZE) {
                // Bug 1326: it's an Integer.
                req.setAttribute(SSLSupport.KEY_SIZE_KEY, readShort(requestContent, offset));
                offset += 2;
            }

            if (attributeCode == AjpConstants.SC_A_REQ_ATTRIBUTE) {
                // 2 strings ???...
                offset = setStringAttribute(req, requestContent, offset);
            }

            // 1 string attributes
            switch (attributeCode) {
            case AjpConstants.SC_A_CONTEXT:
                // nothing
                offset = skipBytes(requestContent, offset);
                break;

            case AjpConstants.SC_A_REMOTE_USER:
                if (tomcatAuthentication) {
                    // ignore server
                    offset = skipBytes(requestContent, offset);
                } else {
                    offset = getBytesToDataChunk(requestContent, offset, req.remoteUser());
                }
                break;

            case AjpConstants.SC_A_AUTH_TYPE:
                if (tomcatAuthentication) {
                    // ignore server
                    offset = skipBytes(requestContent, offset);
                } else {
                    offset = getBytesToDataChunk(requestContent, offset, req.authType());
                }
                break;

            case AjpConstants.SC_A_QUERY_STRING:
                offset = getBytesToDataChunk(requestContent, offset, req.getQueryStringDC());
                break;

            case AjpConstants.SC_A_JVM_ROUTE:
                offset = getBytesToDataChunk(requestContent, offset, req.instanceId());
                break;

            case AjpConstants.SC_A_SSL_CERT:
                req.setSecure(true);
                // SSL certificate extraction is costy, initialize on demand
                offset = getBytesToDataChunk(requestContent, offset, req.sslCert());
                break;

            case AjpConstants.SC_A_SSL_CIPHER:
                req.setSecure(true);
                offset = setStringAttributeValue(req, SSLSupport.CIPHER_SUITE_KEY, requestContent, offset);
                break;

            case AjpConstants.SC_A_SSL_SESSION:
                req.setSecure(true);
                offset = setStringAttributeValue(req, SSLSupport.SESSION_ID_KEY, requestContent, offset);
                break;

            case AjpConstants.SC_A_SECRET:
                offset = getBytesToDataChunk(requestContent, offset, tmpDataChunk);

                req.setSecret(tmpDataChunk.toString());
                tmpDataChunk.recycle();

                break;

            case AjpConstants.SC_A_STORED_METHOD:
                offset = getBytesToDataChunk(requestContent, offset, req.getMethodDC());
                break;

            default:
                break; // ignore, we don't know about it - backward compat
            }
        }

        return offset;
    }

    static int decodeHeaders(final Buffer requestContent, int offset, final AjpHttpRequest req) {
        // Decode headers
        final MimeHeaders headers = req.getHeaders();

        final int hCount = readShort(requestContent, offset);
        offset += 2;

        for (int i = 0; i < hCount; i++) {
            String hName;

            // Header names are encoded as either an integer code starting
            // with 0xA0, or as a normal string (in which case the first
            // two bytes are the length).
            int isc = readShort(requestContent, offset);
            int hId = isc & 0xFF;

            DataChunk valueDC;
            isc &= 0xFF00;
            if (0xA000 == isc) {
                offset += 2;
                hName = AjpConstants.headerTransArray[hId - 1];
                valueDC = headers.addValue(hName);
            } else {
                // reset hId -- if the header currently being read
                // happens to be 7 or 8 bytes long, the code below
                // will think it's the content-type header or the
                // content-length header - SC_REQ_CONTENT_TYPE=7,
                // SC_REQ_CONTENT_LENGTH=8 - leading to unexpected
                // behaviour. see bug 5861 for more information.
                hId = -1;

                final int headerNameLen = readShort(requestContent, offset);
                offset += 2;
                valueDC = headers.addValue(requestContent, offset, headerNameLen);
                // Don't forget to skip the terminating \0 (that's why "+ 1")
                offset += headerNameLen + 1;
            }

            offset = getBytesToDataChunk(requestContent, offset, valueDC);

            // Get the last added header name (the one we need)
            final DataChunk headerNameDC = headers.getName(headers.size() - 1);

            if (hId == AjpConstants.SC_REQ_CONTENT_LENGTH || hId == -1 && headerNameDC.equalsIgnoreCase("Content-Length")) {
                // just read the content-length header, so set it
                final long cl = Ascii.parseLong(valueDC);
                if (cl < Integer.MAX_VALUE) {
                    req.setContentLength((int) cl);
                }
            } else if (hId == AjpConstants.SC_REQ_CONTENT_TYPE || hId == -1 && headerNameDC.equalsIgnoreCase("Content-Type")) {
                // just read the content-type header, so set it
                req.setContentType(valueDC.toString());
            }
        }

        return offset;
    }

    
Parse host.
/**
     * Parse host.
     */
    static void parseHost(final DataChunk hostDC, final DataChunk serverNameDC, final HttpRequestPacket request) {

        if (hostDC == null) {
            // HTTP/1.0
            // Default is what the socket tells us. Overriden if a host is
            // found/parsed
            request.setServerPort(request.getLocalPort());
            serverNameDC.setString(request.getLocalName());
            return;
        }

        final BufferChunk valueBC = hostDC.getBufferChunk();
        final int valueS = valueBC.getStart();
        final int valueL = valueBC.getEnd() - valueS;
        int colonPos = -1;

        final Buffer valueB = valueBC.getBuffer();
        final boolean ipv6 = valueB.get(valueS) == '[';
        boolean bracketClosed = false;
        for (int i = 0; i < valueL; i++) {
            final byte b = valueB.get(i + valueS);
            if (b == ']') {
                bracketClosed = true;
            } else if (b == ':') {
                if (!ipv6 || bracketClosed) {
                    colonPos = i;
                    break;
                }
            }
        }

        if (colonPos < 0) {
            if (!request.isSecure()) {
                // 80 - Default HTTTP port
                request.setServerPort(80);
            } else {
                // 443 - Default HTTPS port
                request.setServerPort(443);
            }
            serverNameDC.setBuffer(valueB, valueS, valueS + valueL);
        } else {
            serverNameDC.setBuffer(valueB, valueS, valueS + colonPos);

            int port = 0;
            int mult = 1;
            for (int i = valueL - 1; i > colonPos; i--) {
                int charValue = DEC[valueB.get(i + valueS)];
                if (charValue == -1) {
                    // Invalid character
                    throw new IllegalStateException(String.format("Host header %s contained a non-decimal value in the port definition.", hostDC.toString()));
                }
                port = port + charValue * mult;
                mult = 10 * mult;
            }
            request.setServerPort(port);

        }

    }

    private static boolean isNullLength(final int length) {
        return length == 0xFFFF || length == -1;
    }

    static int readShort(final Buffer buffer, final int offset) {
        return buffer.getShort(offset) & 0xFFFF;
    }

    static int getBytesToDataChunk(final Buffer buffer, final int offset, final DataChunk dataChunk) {

        final int bytesStart = offset + 2;
        final int length = readShort(buffer, offset);
        if (isNullLength(length)) {
            return bytesStart;
        }

        dataChunk.setBuffer(buffer, bytesStart, bytesStart + length);

        // Don't forget to skip the terminating \0 (that's why "+ 1")
        return bytesStart + length + 1;
    }

    private static int skipBytes(final Buffer buffer, final int offset) {

        final int bytesStart = offset + 2;
        final int length = readShort(buffer, offset);
        if (isNullLength(length)) {
            return bytesStart;
        }

        // Don't forget to skip the terminating \0 (that's why "+ 1")
        return bytesStart + length + 1;
    }

    private static int setStringAttribute(final AjpHttpRequest req, final Buffer buffer, int offset) {
        final DataChunk tmpDataChunk = req.tmpDataChunk;

        offset = getBytesToDataChunk(buffer, offset, tmpDataChunk);
        final String key = tmpDataChunk.toString();

        tmpDataChunk.recycle();

        offset = getBytesToDataChunk(buffer, offset, tmpDataChunk);
        final String value = tmpDataChunk.toString();

        tmpDataChunk.recycle();

        req.setAttribute(key, value);

        return offset;
    }

    private static int setStringAttributeValue(final AjpHttpRequest req, final String key, final Buffer buffer, int offset) {

        final DataChunk tmpDataChunk = req.tmpDataChunk;

        offset = getBytesToDataChunk(buffer, offset, tmpDataChunk);
        final String value = tmpDataChunk.toString();

        tmpDataChunk.recycle();

        req.setAttribute(key, value);
        return offset;
    }

    public static Buffer encodeHeaders(final MemoryManager mm, final HttpResponsePacket httpResponsePacket) {
        Buffer encodedBuffer = mm.allocate(4096);
        int startPos = encodedBuffer.position();
        // Skip 4 bytes for the Ajp header
        encodedBuffer.position(startPos + 4);

        encodedBuffer.put(AjpConstants.JK_AJP13_SEND_HEADERS);
        encodedBuffer.putShort((short) httpResponsePacket.getStatus());
        final byte[] tempBuffer = httpResponsePacket.getTempHeaderEncodingBuffer();
        if (httpResponsePacket.isCustomReasonPhraseSet()) {
            encodedBuffer = putBytes(mm, encodedBuffer, HttpUtils.filter(httpResponsePacket.getReasonPhraseDC()), tempBuffer);
        } else {
            encodedBuffer = putBytes(mm, encodedBuffer, httpResponsePacket.getHttpStatus().getReasonPhraseBytes());
        }

        if (httpResponsePacket.isAcknowledgement()) {
            // If it's acknoledgment packet - don't encode the headers
            // Serialize 0 num_headers
            encodedBuffer = putShort(mm, encodedBuffer, 0);
        } else {
            final MimeHeaders headers = httpResponsePacket.getHeaders();
            final String contentType = httpResponsePacket.getContentType();
            if (contentType != null) {
                headers.setValue("Content-Type").setString(contentType);
            }
            final String contentLanguage = httpResponsePacket.getContentLanguage();
            if (contentLanguage != null) {
                headers.setValue("Content-Language").setString(contentLanguage);
            }
            final long contentLength = httpResponsePacket.getContentLength();
            if (contentLength >= 0) {
                final Buffer contentLengthBuffer = getLongAsBuffer(mm, contentLength);
                headers.setValue("Content-Length").setBuffer(contentLengthBuffer, contentLengthBuffer.position(), contentLengthBuffer.limit());
            }

            final int numHeaders = headers.size();

            encodedBuffer = putShort(mm, encodedBuffer, numHeaders);

            for (int i = 0; i < numHeaders; i++) {
                final DataChunk headerName = headers.getName(i);
                encodedBuffer = putBytes(mm, encodedBuffer, headerName, tempBuffer);

                final DataChunk headerValue = headers.getValue(i);
                encodedBuffer = putBytes(mm, encodedBuffer, headerValue, tempBuffer);
            }
        }

        // Add Ajp message header
        encodedBuffer.put(startPos, (byte) 'A');
        encodedBuffer.put(startPos + 1, (byte) 'B');
        encodedBuffer.putShort(startPos + 2, (short) (encodedBuffer.position() - startPos - 4));

        return encodedBuffer;
    }

    private static final int BODY_CHUNK_HEADER_SIZE = 7;
    private static final int MAX_BODY_CHUNK_CONTENT_SIZE = AjpConstants.SUGGESTED_MAX_PAYLOAD_SIZE - BODY_CHUNK_HEADER_SIZE - 1; // -1 because of terminating \0

    public static Buffer appendContentAndTrim(final MemoryManager memoryManager, Buffer dstBuffer, Buffer httpContentBuffer) {
        Buffer resultBuffer = null;
        do {
            Buffer contentRemainder = null;
            if (httpContentBuffer.remaining() > MAX_BODY_CHUNK_CONTENT_SIZE) {
                contentRemainder = httpContentBuffer.split(httpContentBuffer.position() + MAX_BODY_CHUNK_CONTENT_SIZE);
            }

            final Buffer encodedContentChunk = appendContentChunkAndTrim(memoryManager, dstBuffer, httpContentBuffer);
            resultBuffer = Buffers.appendBuffers(memoryManager, resultBuffer, encodedContentChunk);

            // dstBuffer use only once, when it comes from caller
            dstBuffer = null;
            httpContentBuffer = contentRemainder;
        } while (httpContentBuffer != null && httpContentBuffer.hasRemaining());

        return resultBuffer;
    }

    private static Buffer appendContentChunkAndTrim(final MemoryManager memoryManager, final Buffer dstBuffer, final Buffer httpContentBuffer) {

        final boolean useDstBufferForHeaders = dstBuffer != null && dstBuffer.remaining() >= BODY_CHUNK_HEADER_SIZE;

        final Buffer headerBuffer;
        if (useDstBufferForHeaders) {
            headerBuffer = dstBuffer;
        } else {
            if (dstBuffer != null) {
                dstBuffer.trim();
            }
            headerBuffer = memoryManager.allocate(BODY_CHUNK_HEADER_SIZE);
            headerBuffer.allowBufferDispose(true);
        }

        headerBuffer.put((byte) 'A');
        headerBuffer.put((byte) 'B');
        headerBuffer.putShort((short) (4 + httpContentBuffer.remaining()));
        headerBuffer.put(AjpConstants.JK_AJP13_SEND_BODY_CHUNK);
        headerBuffer.putShort((short) httpContentBuffer.remaining());
        headerBuffer.trim();

        Buffer resultBuffer = Buffers.appendBuffers(memoryManager, headerBuffer, httpContentBuffer);

        // Add terminating \0
        final Buffer terminatingBuffer = memoryManager.allocate(1);
        terminatingBuffer.allowBufferDispose(true);

        resultBuffer = Buffers.appendBuffers(memoryManager, resultBuffer, terminatingBuffer);

        if (!useDstBufferForHeaders && dstBuffer != null) {
            resultBuffer = Buffers.appendBuffers(memoryManager, dstBuffer, resultBuffer);
        }

        if (resultBuffer.isComposite()) {
            // If during buffer appending - composite buffer was created -
            // allow buffer disposing
            ((CompositeBuffer) resultBuffer).allowInternalBuffersDispose(true);
        }

        return resultBuffer;
    }

    private static Buffer putBytes(final MemoryManager memoryManager, Buffer dstBuffer, final DataChunk dataChunk, final byte[] tempBuffer) {
        if (dataChunk == null || dataChunk.isNull()) {
            return putBytes(memoryManager, dstBuffer, EMPTY_BYTE_ARRAY);
        }

        final int size = dataChunk.getLength();

        // Don't forget the terminating \0 (that's why "+ 1")
        if (dstBuffer.remaining() < size + 2 + 1) {
            dstBuffer = resizeBuffer(memoryManager, dstBuffer, size + 2 + 1);
        }

        dstBuffer.putShort((short) size);

        dstBuffer = put(memoryManager, dstBuffer, tempBuffer, dataChunk);
        // Don't forget the terminating \0
        dstBuffer.put((byte) 0);

        return dstBuffer;
    }

    private static Buffer putBytes(final MemoryManager memoryManager, Buffer dstBuffer, final byte[] bytes) {
        final int size = bytes.length;

        // Don't forget the terminating \0 (that's why "+ 1")
        if (dstBuffer.remaining() < size + 2 + 1) {
            dstBuffer = resizeBuffer(memoryManager, dstBuffer, size + 2 + 1);
        }

        dstBuffer.putShort((short) size);

        dstBuffer = put(memoryManager, dstBuffer, bytes);
        // Don't forget the terminating \0
        dstBuffer.put((byte) 0);

        return dstBuffer;
    }

    private static Buffer putShort(final MemoryManager memoryManager, Buffer dstBuffer, final int value) {
        if (dstBuffer.remaining() < 2) {
            dstBuffer = resizeBuffer(memoryManager, dstBuffer, 2);
        }
        dstBuffer.putShort((short) value);

        return dstBuffer;
    }
}