zipkin2.SpanBytesDecoderDetector Maven / Gradle / Ivy
/*
* Copyright The OpenZipkin Authors
* SPDX-License-Identifier: Apache-2.0
*/
package zipkin2;
import java.nio.ByteBuffer;
import zipkin2.codec.BytesDecoder;
import zipkin2.codec.SpanBytesDecoder;
/**
* Detecting decoder used in transports which don't include means to identify the type of the data.
*
* For example, we can identify the encoding and also the format in http via the request path
* and content-type. However, in Kafka it could be that folks send mixed Zipkin data without
* identifying its format. For example, Kafka historically has no content-type and users don't
* always segregate different queues by instrumentation format.
*/
// In TBinaryProtocol encoding, the first byte is the TType, in a range 0-16
// .. If the first byte isn't in that range, it isn't a thrift.
//
// When byte(0) == '[' (91), assume it is a list of json-encoded spans
//
// When byte(0) == 10, assume it is a proto3-encoded span or trace ID field
//
// When byte(0) <= 16, assume it is a TBinaryProtocol-encoded thrift
// .. When serializing a Span (Struct), the first byte will be the type of a field
// .. When serializing a List[ThriftSpan], the first byte is the member type, TType.STRUCT(12)
// .. As ThriftSpan has no STRUCT fields: so, if the first byte is TType.STRUCT(12), it is a list.
public final class SpanBytesDecoderDetector {
/**
* Zipkin v2 json will have "localEndpoint" or "remoteEndpoint" fields, and others won't.
*
*
Note: Technically, it is also possible that one can thwart this by creating an binary
* annotation of type string with a name or value literally ending in Endpoint. This would be
* strange, especially as the convention to identify a local endpoint is the key "lc". To prevent
* a secondary check, this scenario is also ignored.
*/
static final byte[] ENDPOINT_FIELD_SUFFIX = {'E', 'n', 'd', 'p', 'o', 'i', 'n', 't', '"'};
/**
* Technically, it is possible to have a v2 span with no endpoints. This should catch the case
* where someone reported a tag without reporting the "localEndpoint".
*
*
Note: we don't check for annotations as that exists in both v1 and v2 formats.
*/
static final byte[] TAGS_FIELD = {'"', 't', 'a', 'g', 's', '"'};
/**
* Throws {@link IllegalArgumentException} if the input isn't a v1 json or thrift single-span
* message
*/
public static BytesDecoder decoderForMessage(byte[] span) {
BytesDecoder decoder = detectDecoder(ByteBuffer.wrap(span));
if (span[0] == 12 /* List[ThriftSpan] */ || span[0] == '[') {
throw new IllegalArgumentException("Expected json or thrift object, not list encoding");
}
if (decoder == SpanBytesDecoder.JSON_V2 || decoder == SpanBytesDecoder.PROTO3) {
throw new UnsupportedOperationException("v2 formats should only be used with list messages");
}
return decoder;
}
/**
* Throws {@link IllegalArgumentException} if the input isn't a json, proto3 or thrift list
* message.
*/
public static BytesDecoder decoderForListMessage(byte[] spans) {
return decoderForListMessage(ByteBuffer.wrap(spans));
}
public static BytesDecoder decoderForListMessage(ByteBuffer spans) {
BytesDecoder decoder = detectDecoder(spans);
byte first = spans.get(spans.position());
if (first != 12 /* List[ThriftSpan] */
&& first != 11 /* openzipkin/zipkin-reporter-java#133 */
&& !protobuf3(spans) && first != '[') {
throw new IllegalArgumentException("Expected json, proto3 or thrift list encoding");
}
return decoder;
}
/** @throws IllegalArgumentException if the input isn't a json or thrift list or object. */
static BytesDecoder detectDecoder(ByteBuffer bytes) {
byte first = bytes.get(bytes.position());
if (first <= 16) { // binary format
if (protobuf3(bytes)) return SpanBytesDecoder.PROTO3;
return SpanBytesDecoder.THRIFT; /* the first byte is the TType, in a range 0-16 */
} else if (first != '[' && first != '{') {
throw new IllegalArgumentException("Could not detect the span format");
}
if (contains(bytes, ENDPOINT_FIELD_SUFFIX)) return SpanBytesDecoder.JSON_V2;
if (contains(bytes, TAGS_FIELD)) return SpanBytesDecoder.JSON_V2;
return SpanBytesDecoder.JSON_V1;
}
static boolean contains(ByteBuffer bytes, byte[] subsequence) {
bytes:
for (int i = 0; i < bytes.remaining() - subsequence.length + 1; i++) {
for (int j = 0; j < subsequence.length; j++) {
if (bytes.get(bytes.position() + i + j) != subsequence[j]) {
continue bytes;
}
}
return true;
}
return false;
}
/* span key or trace ID key */
static boolean protobuf3(ByteBuffer bytes) {
// varint follows and won't be zero
return bytes.get(bytes.position()) == 10 && bytes.get(bytes.position() + 1) != 0;
}
SpanBytesDecoderDetector() {
}
}