in http-core/src/main/java/org/apache/pekko/http/shaded/com/twitter/hpack/Decoder.java [103:395]
public void decode(InputStream in, HeaderListener headerListener) throws IOException {
while (in.available() > 0) {
switch (state) {
case READ_HEADER_REPRESENTATION:
byte b = (byte) in.read();
if (maxDynamicTableSizeChangeRequired && (b & 0xE0) != 0x20) {
// Encoder MUST signal maximum dynamic table size change
throw MAX_DYNAMIC_TABLE_SIZE_CHANGE_REQUIRED;
}
if (b < 0) {
// Indexed Header Field
index = b & 0x7F;
if (index == 0) {
throw ILLEGAL_INDEX_VALUE;
} else if (index == 0x7F) {
state = State.READ_INDEXED_HEADER;
} else {
indexHeader(index, headerListener);
}
} else if ((b & 0x40) == 0x40) {
// Literal Header Field with Incremental Indexing
indexType = IndexType.INCREMENTAL;
index = b & 0x3F;
if (index == 0) {
state = State.READ_LITERAL_HEADER_NAME_LENGTH_PREFIX;
} else if (index == 0x3F) {
state = State.READ_INDEXED_HEADER_NAME;
} else {
// Index was stored as the prefix
readName(index);
state = State.READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX;
}
} else if ((b & 0x20) == 0x20) {
// Dynamic Table Size Update
index = b & 0x1F;
if (index == 0x1F) {
state = State.READ_MAX_DYNAMIC_TABLE_SIZE;
} else {
setDynamicTableSize(index);
state = State.READ_HEADER_REPRESENTATION;
}
} else {
// Literal Header Field without Indexing / never Indexed
indexType = ((b & 0x10) == 0x10) ? IndexType.NEVER : IndexType.NONE;
index = b & 0x0F;
if (index == 0) {
state = State.READ_LITERAL_HEADER_NAME_LENGTH_PREFIX;
} else if (index == 0x0F) {
state = State.READ_INDEXED_HEADER_NAME;
} else {
// Index was stored as the prefix
readName(index);
state = State.READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX;
}
}
break;
case READ_MAX_DYNAMIC_TABLE_SIZE:
int maxSize = decodeULE128(in);
if (maxSize == -1) {
return;
}
// Check for numerical overflow
if (maxSize > Integer.MAX_VALUE - index) {
throw DECOMPRESSION_EXCEPTION;
}
setDynamicTableSize(index + maxSize);
state = State.READ_HEADER_REPRESENTATION;
break;
case READ_INDEXED_HEADER:
int headerIndex = decodeULE128(in);
if (headerIndex == -1) {
return;
}
// Check for numerical overflow
if (headerIndex > Integer.MAX_VALUE - index) {
throw DECOMPRESSION_EXCEPTION;
}
indexHeader(index + headerIndex, headerListener);
state = State.READ_HEADER_REPRESENTATION;
break;
case READ_INDEXED_HEADER_NAME:
// Header Name matches an entry in the Header Table
int nameIndex = decodeULE128(in);
if (nameIndex == -1) {
return;
}
// Check for numerical overflow
if (nameIndex > Integer.MAX_VALUE - index) {
throw DECOMPRESSION_EXCEPTION;
}
readName(index + nameIndex);
state = State.READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX;
break;
case READ_LITERAL_HEADER_NAME_LENGTH_PREFIX:
b = (byte) in.read();
huffmanEncoded = (b & 0x80) == 0x80;
index = b & 0x7F;
if (index == 0x7f) {
state = State.READ_LITERAL_HEADER_NAME_LENGTH;
} else {
nameLength = index;
// Disallow empty names -- they cannot be represented in HTTP/1.x
if (nameLength == 0) {
throw DECOMPRESSION_EXCEPTION;
}
// Check name length against max header size
if (exceedsMaxHeaderSize(nameLength)) {
if (indexType == IndexType.NONE) {
// Name is unused so skip bytes
name = EMPTY;
skipLength = nameLength;
state = State.SKIP_LITERAL_HEADER_NAME;
break;
}
// Check name length against max dynamic table size
if (nameLength + HEADER_ENTRY_OVERHEAD > dynamicTable.capacity()) {
dynamicTable.clear();
name = EMPTY;
skipLength = nameLength;
state = State.SKIP_LITERAL_HEADER_NAME;
break;
}
}
state = State.READ_LITERAL_HEADER_NAME;
}
break;
case READ_LITERAL_HEADER_NAME_LENGTH:
// Header Name is a Literal String
nameLength = decodeULE128(in);
if (nameLength == -1) {
return;
}
// Check for numerical overflow
if (nameLength > Integer.MAX_VALUE - index) {
throw DECOMPRESSION_EXCEPTION;
}
nameLength += index;
// Check name length against max header size
if (exceedsMaxHeaderSize(nameLength)) {
if (indexType == IndexType.NONE) {
// Name is unused so skip bytes
name = EMPTY;
skipLength = nameLength;
state = State.SKIP_LITERAL_HEADER_NAME;
break;
}
// Check name length against max dynamic table size
if (nameLength + HEADER_ENTRY_OVERHEAD > dynamicTable.capacity()) {
dynamicTable.clear();
name = EMPTY;
skipLength = nameLength;
state = State.SKIP_LITERAL_HEADER_NAME;
break;
}
}
state = State.READ_LITERAL_HEADER_NAME;
break;
case READ_LITERAL_HEADER_NAME:
// Wait until entire name is readable
if (in.available() < nameLength) {
return;
}
name = readStringLiteral(in, nameLength);
state = State.READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX;
break;
case SKIP_LITERAL_HEADER_NAME:
skipLength -= in.skip(skipLength);
if (skipLength == 0) {
state = State.READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX;
}
break;
case READ_LITERAL_HEADER_VALUE_LENGTH_PREFIX:
b = (byte) in.read();
huffmanEncoded = (b & 0x80) == 0x80;
index = b & 0x7F;
if (index == 0x7f) {
state = State.READ_LITERAL_HEADER_VALUE_LENGTH;
} else {
valueLength = index;
// Check new header size against max header size
long newHeaderSize = (long) nameLength + (long) valueLength;
if (exceedsMaxHeaderSize(newHeaderSize)) {
// truncation will be reported during endHeaderBlock
headerSize = maxHeaderSize + 1;
if (indexType == IndexType.NONE) {
// Value is unused so skip bytes
state = State.SKIP_LITERAL_HEADER_VALUE;
break;
}
// Check new header size against max dynamic table size
if (newHeaderSize + HEADER_ENTRY_OVERHEAD > dynamicTable.capacity()) {
dynamicTable.clear();
state = State.SKIP_LITERAL_HEADER_VALUE;
break;
}
}
if (valueLength == 0) {
insertHeader(headerListener, name, EMPTY, indexType);
state = State.READ_HEADER_REPRESENTATION;
} else {
state = State.READ_LITERAL_HEADER_VALUE;
}
}
break;
case READ_LITERAL_HEADER_VALUE_LENGTH:
// Header Value is a Literal String
valueLength = decodeULE128(in);
if (valueLength == -1) {
return;
}
// Check for numerical overflow
if (valueLength > Integer.MAX_VALUE - index) {
throw DECOMPRESSION_EXCEPTION;
}
valueLength += index;
// Check new header size against max header size
long newHeaderSize = (long) nameLength + (long) valueLength;
if (newHeaderSize + headerSize > maxHeaderSize) {
// truncation will be reported during endHeaderBlock
headerSize = maxHeaderSize + 1;
if (indexType == IndexType.NONE) {
// Value is unused so skip bytes
state = State.SKIP_LITERAL_HEADER_VALUE;
break;
}
// Check new header size against max dynamic table size
if (newHeaderSize + HEADER_ENTRY_OVERHEAD > dynamicTable.capacity()) {
dynamicTable.clear();
state = State.SKIP_LITERAL_HEADER_VALUE;
break;
}
}
state = State.READ_LITERAL_HEADER_VALUE;
break;
case READ_LITERAL_HEADER_VALUE:
// Wait until entire value is readable
if (in.available() < valueLength) {
return;
}
String value = readStringLiteral(in, valueLength);
insertHeader(headerListener, name, value, indexType);
state = State.READ_HEADER_REPRESENTATION;
break;
case SKIP_LITERAL_HEADER_VALUE:
valueLength -= in.skip(valueLength);
if (valueLength == 0) {
state = State.READ_HEADER_REPRESENTATION;
}
break;
default:
throw new IllegalStateException("should not reach here");
}
}
}