static Type determineType(final byte first, final byte second) {
if (first == ZLIB.first()) {
// zlib's second byte is for flags and a checksum -
// make sure it is positive.
int secondInt = ZLIB.second();
if (second < 0) {
secondInt += 256;
}
// the second byte is not constant for zlib, it
// differs based on compression level used and whether
// a dictionary is used. What the RFC guarantees is
// that "CMF and FLG, when viewed as a 16-bit unsigned
// integer stored in MSB order (CMF*256 + FLG), is a
// multiple of 31"
if ((256 * first + secondInt) % 31 == 0) {
return ZLIB;
} else {
return UNSUPPORTED;
}
} else if (first == GZIP.first()) {
if (second == GZIP.second()) {
return GZIP;
} else {
return UNSUPPORTED;
}
} else if (first == CHUNKED.first()) {
if (second == CHUNKED.second()) {
return CHUNKED;
} else {
return UNSUPPORTED;
}
}
// by default assume the payload to be "raw, uncompressed" GELF, parsing will fail if it's
// malformed.
return UNCOMPRESSED;
}
