decode() — netty Function Reference

Architecture documentation for the decode() function in SslClientHelloHandler.java from the netty codebase.

Function java Buffer Allocators calls 1

Entity Profile

Buffer→ Allocators→ decode() — netty Function Reference

Dependency Diagram

graph TD
  fc4692ec_d0ce_218f_173c_dac045c2e3db["decode()"]
  4135ba3a_6a80_65ac_0a45_d76f228bf4b3["SslClientHelloHandler"]
  fc4692ec_d0ce_218f_173c_dac045c2e3db -->|defined in| 4135ba3a_6a80_65ac_0a45_d76f228bf4b3
  0d8db5ff_601a_a9ee_8f6b_b642c82a3338["select()"]
  fc4692ec_d0ce_218f_173c_dac045c2e3db -->|calls| 0d8db5ff_601a_a9ee_8f6b_b642c82a3338
  style fc4692ec_d0ce_218f_173c_dac045c2e3db fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

handler/src/main/java/io/netty/handler/ssl/SslClientHelloHandler.java lines 67–204

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        if (!suppressRead && !handshakeFailed) {
            try {
                int readerIndex = in.readerIndex();
                int readableBytes = in.readableBytes();
                int handshakeLength = -1;

                // Check if we have enough data to determine the record type and length.
                while (readableBytes >= SslUtils.SSL_RECORD_HEADER_LENGTH) {
                    final int contentType = in.getUnsignedByte(readerIndex);
                    switch (contentType) {
                        case SslUtils.SSL_CONTENT_TYPE_CHANGE_CIPHER_SPEC:
                            // fall-through
                        case SslUtils.SSL_CONTENT_TYPE_ALERT:
                            final int len = SslUtils.getEncryptedPacketLength(in, readerIndex, true);

                            // Not an SSL/TLS packet
                            if (len == SslUtils.NOT_ENCRYPTED) {
                                handshakeFailed = true;
                                NotSslRecordException e = new NotSslRecordException(
                                        "not an SSL/TLS record: " + ByteBufUtil.hexDump(in));
                                in.skipBytes(in.readableBytes());
                                ctx.fireUserEventTriggered(new SniCompletionEvent(e));
                                SslUtils.handleHandshakeFailure(ctx, e, true);
                                throw e;
                            }
                            if (len == SslUtils.NOT_ENOUGH_DATA) {
                                // Not enough data
                                return;
                            }
                            // No ClientHello
                            select(ctx, null);
                            return;
                        case SslUtils.SSL_CONTENT_TYPE_HANDSHAKE:
                            final int majorVersion = in.getUnsignedByte(readerIndex + 1);
                            // SSLv3 or TLS
                            if (majorVersion == 3) {
                                int packetLength = in.getUnsignedShort(readerIndex + 3) +
                                        SslUtils.SSL_RECORD_HEADER_LENGTH;

                                if (readableBytes < packetLength) {
                                    // client hello incomplete; try again to decode once more data is ready.
                                    return;
                                } else if (packetLength == SslUtils.SSL_RECORD_HEADER_LENGTH) {
                                    select(ctx, null);
                                    return;
                                }

                                final int endOffset = readerIndex + packetLength;

                                // Let's check if we already parsed the handshake length or not.
                                if (handshakeLength == -1) {
                                    if (readerIndex + 4 > endOffset) {
                                        // Need more data to read HandshakeType and handshakeLength (4 bytes)
                                        return;
                                    }

                                    final int handshakeType = in.getUnsignedByte(readerIndex +
                                            SslUtils.SSL_RECORD_HEADER_LENGTH);

                                    // Check if this is a clientHello(1)
                                    // See https://tools.ietf.org/html/rfc5246#section-7.4
                                    if (handshakeType != 1) {
                                        select(ctx, null);
                                        return;
                                    }

                                    // Read the length of the handshake as it may arrive in fragments
                                    // See https://tools.ietf.org/html/rfc5246#section-7.4
                                    handshakeLength = in.getUnsignedMedium(readerIndex +
                                            SslUtils.SSL_RECORD_HEADER_LENGTH + 1);

                                    if (handshakeLength > maxClientHelloLength && maxClientHelloLength != 0) {
                                        TooLongFrameException e = new TooLongFrameException(
                                                "ClientHello length exceeds " + maxClientHelloLength +
                                                        ": " + handshakeLength);
                                        in.skipBytes(in.readableBytes());
                                        ctx.fireUserEventTriggered(new SniCompletionEvent(e));
                                        SslUtils.handleHandshakeFailure(ctx, e, true);
                                        throw e;