uint32_t HPACKDecoder::decodeLiteralHeader(HPACKDecodeBuffer& dbuf,
headers_t* emitted) {
uint8_t byte = dbuf.peek();
bool indexing = byte & HPACK::HeaderEncoding::LITERAL_INCR_INDEXING;
HPACKHeader header;
uint8_t indexMask = 0x3F; // 0011 1111
uint8_t length = 6;
if (!indexing) {
bool tableSizeUpdate = byte & HPACK::HeaderEncoding::TABLE_SIZE_UPDATE;
if (tableSizeUpdate) {
handleTableSizeUpdate(dbuf);
return 0;
} else {
bool neverIndex = byte & HPACK::HeaderEncoding::LITERAL_NEVER_INDEXING;
// TODO: we need to emit this flag with the headers
}
indexMask = 0x0F; // 0000 1111
length = 4;
}
if (byte & indexMask) {
uint32_t index;
err_ = dbuf.decodeInteger(length, index);
if (err_ != HPACK::DecodeError::NONE) {
LOG(ERROR) << "Decode error decoding index err_=" << err_;
return 0;
}
// validate the index
if (!isValid(index)) {
LOG(ERROR) << "received invalid index: " << index;
err_ = HPACK::DecodeError::INVALID_INDEX;
return 0;
}
header.name = getHeader(index).name;
} else {
// skip current byte
dbuf.next();
err_ = dbuf.decodeLiteral(header.name);
if (err_ != HPACK::DecodeError::NONE) {
LOG(ERROR) << "Error decoding header name err_=" << err_;
return 0;
}
}
// value
err_ = dbuf.decodeLiteral(header.value);
if (err_ != HPACK::DecodeError::NONE) {
LOG(ERROR) << "Error decoding header value name=" << header.name
<< " err_=" << err_;
return 0;
}
uint32_t emittedSize = emit(header, emitted);
if (indexing) {
table_.add(header);
}
return emittedSize;
}
uint32_t HPACKDecoder::decodeIndexedHeader(HPACKDecodeBuffer& dbuf,
headers_t* emitted) {
uint32_t index;
err_ = dbuf.decodeInteger(7, index);
if (err_ != HPACK::DecodeError::NONE) {
LOG(ERROR) << "Decode error decoding index err_=" << err_;
return 0;
}
// validate the index
if (index == 0 || !isValid(index)) {
LOG(ERROR) << "received invalid index: " << index;
err_ = HPACK::DecodeError::INVALID_INDEX;
return 0;
}
uint32_t emittedSize = 0;
if (isStatic(index)) {
auto& header = getStaticHeader(index);
emittedSize = emit(header, emitted);
} else {
auto& header = getDynamicHeader(index);
emittedSize = emit(header, emitted);
}
return emittedSize;
}
uint32_t HPACKDecoder::decodeLiteralHeader(HPACKDecodeBuffer& dbuf,
headers_t* emitted) {
uint8_t byte = dbuf.peek();
bool indexing = !(byte & HPACK::HeaderEncoding::LITERAL_NO_INDEXING);
HPACKHeader header;
// check for indexed name
const uint8_t indexMask = 0x3F; // 0011 1111
if (byte & indexMask) {
uint32_t index;
err_ = dbuf.decodeInteger(6, index);
if (err_ != DecodeError::NONE) {
LOG(ERROR) << "Decode error decoding literal index err_=" << err_;
return 0;
}
// validate the index
if (!isValid(index)) {
LOG(ERROR) << "received invalid index: " << index;
err_ = DecodeError::INVALID_INDEX;
return 0;
}
header.name = getHeader(index).name;
} else {
// skip current byte
dbuf.next();
err_ = dbuf.decodeLiteral(header.name);
if (err_ != DecodeError::NONE) {
LOG(ERROR) << "Error decoding header name err_=" << err_;
return 0;
}
}
// value
err_ = dbuf.decodeLiteral(header.value);
if (err_ != DecodeError::NONE) {
LOG(ERROR) << "Error decoding header value name=" << header.name
<< " err_=" << err_;
return 0;
}
uint32_t emittedSize = emit(header, emitted);
if (indexing && table_.add(header)) {
// only add it to the refset if the header fit in the table
table_.addReference(1);
}
return emittedSize;
}
uint32_t HPACKDecoder::decodeHeader(HPACKDecodeBuffer& dbuf,
headers_t* emitted) {
uint8_t byte = dbuf.peek();
if (byte & HPACK::HeaderEncoding::INDEXED) {
return decodeIndexedHeader(dbuf, emitted);
}
// LITERAL_NO_INDEXING or LITERAL_INCR_INDEXING
return decodeLiteralHeader(dbuf, emitted);
}
void HPACKDecoder::handleTableSizeUpdate(HPACKDecodeBuffer& dbuf) {
uint32_t arg = 0;
err_ = dbuf.decodeInteger(5, arg);
if (err_ != HPACK::DecodeError::NONE) {
LOG(ERROR) << "Decode error decoding maxSize err_=" << err_;
return;
}
if (arg > maxTableSize_) {
LOG(ERROR) << "Tried to increase size of the header table";
err_ = HPACK::DecodeError::INVALID_TABLE_SIZE;
return;
}
table_.setCapacity(arg);
}
uint32_t HPACKDecoder::decodeIndexedHeader(HPACKDecodeBuffer& dbuf,
headers_t* emitted) {
uint32_t index;
err_ = dbuf.decodeInteger(7, index);
if (err_ != DecodeError::NONE) {
LOG(ERROR) << "Decode error decoding header index err_=" << err_;
return 0;
}
if (index == 0) {
table_.clearReferenceSet();
return 0;
}
// validate the index
if (!isValid(index)) {
LOG(ERROR) << "received invalid index: " << index;
err_ = DecodeError::INVALID_INDEX;
return 0;
}
uint32_t emittedSize = 0;
// a static index cannot be part of the reference set
if (isStatic(index)) {
auto& header = getStaticHeader(index);
emittedSize = emit(header, emitted);
if (table_.add(header)) {
table_.addReference(1);
}
} else if (table_.inReferenceSet(globalToDynamicIndex(index))) {
// index remove operation
table_.removeReference(globalToDynamicIndex(index));
} else {
auto& header = getDynamicHeader(index);
emittedSize = emit(header, emitted);
table_.addReference(globalToDynamicIndex(index));
}
return emittedSize;
}
