// Simple recursive parser for ASN1 BER.
private MHParseNode DoParse()
{
byte ch;
// Tag class
int tagClass = Universal;
// Byte count of end of this item. Set to INDEFINITE_LENGTH if the length is Indefinite.
int endOfItem;
int tagNumber = 0;
// Read the first character.
ch = GetNextChar();
// ASN1 Coding rules: Top two bits (0 and 1) indicate the tag class.
// 0x00 - Universal, 0x40 - Application, 0x80 - Context-specific, 0xC0 - Private
// We only use Universal and Context.
switch (ch & 0xC0)
{
case 0x00: // Universal
tagClass = Universal;
break;
case 0x80:
tagClass = Context;
break;
default:
throw new MHEGException("Invalid tag class = " + ch);
}
// Bit 2 indicates whether it is a simple or compound type. Not used.
// Lower bits are the tag number.
tagNumber = ch & 0x1f;
if (tagNumber == 0x1f) // Except that if it is 0x1F then the tag is encoded in the following bytes.
{
tagNumber = 0;
do
{
ch = GetNextChar();
tagNumber = (tagNumber << 7) | (ch & 0x7f);
} while ((ch & 0x80) != 0); // Top bit set means there's more to come.
}
// Next byte is the length. If it is less than 128 it is the actual length, otherwise it
// gives the number of bytes containing the length, except that if this is zero the item
// has an "indefinite" length and is terminated by two zero bytes.
ch = GetNextChar();
if ((ch & 0x80) != 0)
{
int lengthOfLength = ch & 0x7f;
if (lengthOfLength == 0)
{
endOfItem = INDEFINITE_LENGTH;
}
else
{
endOfItem = 0;
while ((lengthOfLength--) != 0)
{
ch = GetNextChar();
endOfItem = (endOfItem << 8) | ch;
}
endOfItem += m_p;
}
}
else
{
endOfItem = ch + m_p;
}
if (tagClass == Context)
{
MHPTagged pNode = new MHPTagged(tagNumber);
// The argument here depends on the particular tag we're processing.
switch (tagNumber)
{
case ASN1Codes.C_MULTIPLE_SELECTION:
case ASN1Codes.C_OBSCURED_INPUT:
case ASN1Codes.C_INITIALLY_AVAILABLE:
case ASN1Codes.C_WRAP_AROUND:
case ASN1Codes.C_TEXT_WRAPPING:
case ASN1Codes.C_INITIALLY_ACTIVE:
case ASN1Codes.C_MOVING_CURSOR:
case ASN1Codes.C_SHARED:
case ASN1Codes.C_ENGINE_RESP:
case ASN1Codes.C_TILING:
case ASN1Codes.C_BORDERED_BOUNDING_BOX:
{ // BOOL
// If there is no argument we need to indicate that so that it gets
// the correct default value.
if (m_p != endOfItem)
{
int intVal = ParseInt(endOfItem); // May raise an exception
pNode.AddArg(new MHPBool(intVal != 0));
}
break;
}
case ASN1Codes.C_INPUT_TYPE:
case ASN1Codes.C_SLIDER_STYLE:
case ASN1Codes.C_TERMINATION:
case ASN1Codes.C_ORIENTATION:
case ASN1Codes.C_HORIZONTAL_JUSTIFICATION:
case ASN1Codes.C_BUTTON_STYLE:
case ASN1Codes.C_START_CORNER:
case ASN1Codes.C_LINE_ORIENTATION:
case ASN1Codes.C_VERTICAL_JUSTIFICATION:
case ASN1Codes.C_STORAGE:
{ // ENUM
if (m_p != endOfItem)
{
int intVal = ParseInt(endOfItem); // May raise an exception
pNode.AddArg(new MHPEnum(intVal));
}
break;
}
case ASN1Codes.C_INITIAL_PORTION:
case ASN1Codes.C_STEP_SIZE:
case ASN1Codes.C_INPUT_EVENT_REGISTER:
case ASN1Codes.C_INITIAL_VALUE:
case ASN1Codes.C_IP_CONTENT_HOOK:
case ASN1Codes.C_MAX_VALUE:
case ASN1Codes.C_MIN_VALUE:
case ASN1Codes.C_LINE_ART_CONTENT_HOOK:
case ASN1Codes.C_BITMAP_CONTENT_HOOK:
case ASN1Codes.C_TEXT_CONTENT_HOOK:
case ASN1Codes.C_STREAM_CONTENT_HOOK:
case ASN1Codes.C_MAX_LENGTH:
case ASN1Codes.C_CHARACTER_SET:
case ASN1Codes.C_ORIGINAL_TRANSPARENCY:
case ASN1Codes.C_ORIGINAL_GC_PRIORITY:
case ASN1Codes.C_LOOPING:
case ASN1Codes.C_ORIGINAL_LINE_STYLE:
case ASN1Codes.C_STANDARD_VERSION:
case ASN1Codes.C_ORIGINAL_LINE_WIDTH:
case ASN1Codes.C_CONTENT_HOOK:
case ASN1Codes.C_CONTENT_CACHE_PRIORITY:
case ASN1Codes.C_COMPONENT_TAG:
case ASN1Codes.C_ORIGINAL_VOLUME:
case ASN1Codes.C_PROGRAM_CONNECTION_TAG:
case ASN1Codes.C_CONTENT_SIZE:
{ // INT
if (m_p != endOfItem)
{
int intVal = ParseInt(endOfItem); // May raise an exception
pNode.AddArg(new MHPInt(intVal));
}
break;
}
case ASN1Codes.C_OBJECT_INFORMATION:
case ASN1Codes.C_CONTENT_REFERENCE:
case ASN1Codes.C_FONT_ATTRIBUTES:
case ASN1Codes.C_CHAR_LIST:
case ASN1Codes.C_NAME:
case ASN1Codes.C_ORIGINAL_LABEL:
{ // STRING
// Unlike INT, BOOL and ENUM we can't distinguish an empty string
// from a missing string.
MHOctetString str = new MHOctetString();
ParseString(endOfItem, str);
pNode.AddArg(new MHPString(str));
break;
}
default:
{
// Everything else has either no argument or is self-describing
// TODO: Handle indefinite length.
Logging.Assert(endOfItem != INDEFINITE_LENGTH); // For the moment.
while (m_p < endOfItem)
{
pNode.AddArg(DoParse());
}
break;
}
}
return(pNode);
}
else // Universal - i.e. a primitive type.
// Tag values
{
switch (tagNumber)
{
case ASN1Codes.U_BOOL: // Boolean
{
int intVal = ParseInt(endOfItem);
return(new MHPBool(intVal != 0));
}
case ASN1Codes.U_INT: // Integer
{
int intVal = ParseInt(endOfItem);
return(new MHPInt(intVal));
}
case ASN1Codes.U_ENUM: // ENUM
{
int intVal = ParseInt(endOfItem);
return(new MHPEnum(intVal));
}
case ASN1Codes.U_STRING: // String
{
MHOctetString str = new MHOctetString();
ParseString(endOfItem, str);
return(new MHPString(str));
}
case ASN1Codes.U_NULL: // ASN1 NULL
{
return(new MHPNull());
}
case ASN1Codes.U_SEQUENCE: // Sequence
{
MHParseSequence pNode = new MHParseSequence();
Logging.Assert(endOfItem != INDEFINITE_LENGTH); // TODO: Implement this.
while (m_p < endOfItem)
{
pNode.Append(DoParse());
}
Logging.Assert(m_p == endOfItem);
return(pNode);
}
default:
Logging.Assert(false);
throw new MHEGException("Unknown universal");
}
}
}
private MHParseNode DoParse()
{
MHParseNode pRes = null;
switch (m_nType)
{
case PTStartSection: // Open curly bracket
{
NextSym();
// Should be followed by a tag.
if (m_nType != PTTag)
{
Error("Expected ':' after '{'");
}
MHPTagged pTag = new MHPTagged(m_nTag);
pRes = pTag;
NextSym();
while (m_nType != PTEndSection)
{
pTag.AddArg(DoParse());
}
NextSym(); // Remove the close curly bracket.
break;
}
case PTTag: // Tag on its own.
{
int nTag = m_nTag;
MHPTagged pTag = new MHPTagged(nTag);
pRes = pTag;
NextSym();
switch (nTag)
{
case ASN1Codes.C_ITEMS:
case ASN1Codes.C_LINK_EFFECT:
case ASN1Codes.C_ACTIVATE:
case ASN1Codes.C_ADD:
case ASN1Codes.C_ADD_ITEM:
case ASN1Codes.C_APPEND:
case ASN1Codes.C_BRING_TO_FRONT:
case ASN1Codes.C_CALL:
case ASN1Codes.C_CALL_ACTION_SLOT:
case ASN1Codes.C_CLEAR:
case ASN1Codes.C_CLONE:
case ASN1Codes.C_CLOSE_CONNECTION:
case ASN1Codes.C_DEACTIVATE:
case ASN1Codes.C_DEL_ITEM:
case ASN1Codes.C_DESELECT:
case ASN1Codes.C_DESELECT_ITEM:
case ASN1Codes.C_DIVIDE:
case ASN1Codes.C_DRAW_ARC:
case ASN1Codes.C_DRAW_LINE:
case ASN1Codes.C_DRAW_OVAL:
case ASN1Codes.C_DRAW_POLYGON:
case ASN1Codes.C_DRAW_POLYLINE:
case ASN1Codes.C_DRAW_RECTANGLE:
case ASN1Codes.C_DRAW_SECTOR:
case ASN1Codes.C_FORK:
case ASN1Codes.C_GET_AVAILABILITY_STATUS:
case ASN1Codes.C_GET_BOX_SIZE:
case ASN1Codes.C_GET_CELL_ITEM:
case ASN1Codes.C_GET_CURSOR_POSITION:
case ASN1Codes.C_GET_ENGINE_SUPPORT:
case ASN1Codes.C_GET_ENTRY_POINT:
case ASN1Codes.C_GET_FILL_COLOUR:
case ASN1Codes.C_GET_FIRST_ITEM:
case ASN1Codes.C_GET_HIGHLIGHT_STATUS:
case ASN1Codes.C_GET_INTERACTION_STATUS:
case ASN1Codes.C_GET_ITEM_STATUS:
case ASN1Codes.C_GET_LABEL:
case ASN1Codes.C_GET_LAST_ANCHOR_FIRED:
case ASN1Codes.C_GET_LINE_COLOUR:
case ASN1Codes.C_GET_LINE_STYLE:
case ASN1Codes.C_GET_LINE_WIDTH:
case ASN1Codes.C_GET_LIST_ITEM:
case ASN1Codes.C_GET_LIST_SIZE:
case ASN1Codes.C_GET_OVERWRITE_MODE:
case ASN1Codes.C_GET_PORTION:
case ASN1Codes.C_GET_POSITION:
case ASN1Codes.C_GET_RUNNING_STATUS:
case ASN1Codes.C_GET_SELECTION_STATUS:
case ASN1Codes.C_GET_SLIDER_VALUE:
case ASN1Codes.C_GET_TEXT_CONTENT:
case ASN1Codes.C_GET_TEXT_DATA:
case ASN1Codes.C_GET_TOKEN_POSITION:
case ASN1Codes.C_GET_VOLUME:
case ASN1Codes.C_LAUNCH:
case ASN1Codes.C_LOCK_SCREEN:
case ASN1Codes.C_MODULO:
case ASN1Codes.C_MOVE:
case ASN1Codes.C_MOVE_TO:
case ASN1Codes.C_MULTIPLY:
case ASN1Codes.C_OPEN_CONNECTION:
case ASN1Codes.C_PRELOAD:
case ASN1Codes.C_PUT_BEFORE:
case ASN1Codes.C_PUT_BEHIND:
case ASN1Codes.C_QUIT:
case ASN1Codes.C_READ_PERSISTENT:
case ASN1Codes.C_RUN:
case ASN1Codes.C_SCALE_BITMAP:
case ASN1Codes.C_SCALE_VIDEO:
case ASN1Codes.C_SCROLL_ITEMS:
case ASN1Codes.C_SELECT:
case ASN1Codes.C_SELECT_ITEM:
case ASN1Codes.C_SEND_EVENT:
case ASN1Codes.C_SEND_TO_BACK:
case ASN1Codes.C_SET_BOX_SIZE:
case ASN1Codes.C_SET_CACHE_PRIORITY:
case ASN1Codes.C_SET_COUNTER_END_POSITION:
case ASN1Codes.C_SET_COUNTER_POSITION:
case ASN1Codes.C_SET_COUNTER_TRIGGER:
case ASN1Codes.C_SET_CURSOR_POSITION:
case ASN1Codes.C_SET_CURSOR_SHAPE:
case ASN1Codes.C_SET_DATA:
case ASN1Codes.C_SET_ENTRY_POINT:
case ASN1Codes.C_SET_FILL_COLOUR:
case ASN1Codes.C_SET_FIRST_ITEM:
case ASN1Codes.C_SET_FONT_REF:
case ASN1Codes.C_SET_HIGHLIGHT_STATUS:
case ASN1Codes.C_SET_INTERACTION_STATUS:
case ASN1Codes.C_SET_LABEL:
case ASN1Codes.C_SET_LINE_COLOUR:
case ASN1Codes.C_SET_LINE_STYLE:
case ASN1Codes.C_SET_LINE_WIDTH:
case ASN1Codes.C_SET_OVERWRITE_MODE:
case ASN1Codes.C_SET_PALETTE_REF:
case ASN1Codes.C_SET_PORTION:
case ASN1Codes.C_SET_POSITION:
case ASN1Codes.C_SET_SLIDER_VALUE:
case ASN1Codes.C_SET_SPEED:
case ASN1Codes.C_SET_TIMER:
case ASN1Codes.C_SET_TRANSPARENCY:
case ASN1Codes.C_SET_VARIABLE:
case ASN1Codes.C_SET_VOLUME:
case ASN1Codes.C_SPAWN:
case ASN1Codes.C_STEP:
case ASN1Codes.C_STOP:
case ASN1Codes.C_STORE_PERSISTENT:
case ASN1Codes.C_SUBTRACT:
case ASN1Codes.C_TEST_VARIABLE:
case ASN1Codes.C_TOGGLE:
case ASN1Codes.C_TOGGLE_ITEM:
case ASN1Codes.C_TRANSITION_TO:
case ASN1Codes.C_UNLOAD:
case ASN1Codes.C_UNLOCK_SCREEN:
case ASN1Codes.C_CONTENT_REFERENCE:
case ASN1Codes.C_TOKEN_GROUP_ITEMS:
case ASN1Codes.C_POSITIONS:
case ASN1Codes.C_MULTIPLEX:
{ // These are parenthesised in the text form. We have to remove the
// parentheses otherwise we will return a sequence which will not be
// be compatible with the binary form.
if (m_nType != PTStartSeq)
{
Error("Expected '('");
}
NextSym();
while (m_nType != PTEndSeq)
{
pTag.AddArg(DoParse());
}
NextSym(); // Remove the close parenthesis.
break;
}
case ASN1Codes.C_ORIGINAL_CONTENT:
case ASN1Codes.C_NEW_GENERIC_BOOLEAN:
case ASN1Codes.C_NEW_GENERIC_INTEGER:
case ASN1Codes.C_NEW_GENERIC_OCTETSTRING:
case ASN1Codes.C_NEW_GENERIC_OBJECT_REF:
case ASN1Codes.C_NEW_GENERIC_CONTENT_REF:
case ASN1Codes.C_ORIGINAL_VALUE:
case ASN1Codes.C_INDIRECTREFERENCE:
// These always have an argument which may be a tagged item.
{
// Is it always the case that there is at least one argument so if we haven't
// had any arguments yet we should always process a tag as an argument?
pTag.AddArg(DoParse());
break;
}
default:
// This can be followed by an int, etc but a new tag is dealt with by the caller.
while (m_nType == PTBool || m_nType == PTInt || m_nType == PTString || m_nType == PTEnum || m_nType == PTStartSeq)
{
pTag.AddArg(DoParse());
}
break;
}
break;
}
case PTInt:
{
pRes = new MHPInt(m_nInt);
NextSym();
break;
}
case PTBool:
{
pRes = new MHPBool(m_fBool);
NextSym();
break;
}
case PTString:
{
MHOctetString str = new MHOctetString();
// str.Copy(MHOctetString((const char *)m_String, m_nStringLength));
str.Copy(m_String);
pRes = new MHPString(str);
NextSym();
break;
}
case PTEnum:
{
pRes = new MHPEnum(m_nInt);
// ASSERT(m_nInt > 0);
NextSym();
break;
}
case PTNull:
{
pRes = new MHPNull();
NextSym();
break;
}
case PTStartSeq: // Open parenthesis.
{
MHParseSequence pSeq = new MHParseSequence();
pRes = pSeq;
NextSym();
while (m_nType != PTEndSeq)
{
pSeq.Append(DoParse());
}
NextSym(); // Remove the close parenthesis.
break;
}
default:
Error("Unexpected symbol");
break;
}
return(pRes);
}